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, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240208
Abstract:
Permian Lucaogou Formation in Jinan Depression, Junggar Basin Geochemical characteristics and oil source analysis of source rocks
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240443
Abstract:
[Objective] In recent years, significant progress has been made in the exploration of conventional sandstone reservoirs in Jingjingzigou Formation, Jinan Depression, Junggar Basin, with tertiary reserves exceeding 100 million tons and excellent exploration prospect. Although the main source rock as Lucaogou Formation of Middle Permian in Jinan Depression has been realized based on former research, the study on geochemical characteristics of source rocks and oil source correlation have been rarely reported. [Methods] Based on comprehensive utilization of test data such as total organic carbon, rock pyrolysis and characteristics of biomarkers,The geochemical characteristics of source rocks in different intervals of Lucaogou Formation and oils source correlation of Middle Permian have been studied in this paper. [Results]The results show that:①Lucaogou Formation can be divided into three sections according to the characteristics of logging curves. P2l1 and P2l2 are excellent with high organic carbon content, hydrocarbon generation potential and soluble organic matter content, organic matter type asⅠ-Ⅱ1 and maturity as early to peak, while P2l2 is better. The main of P2l3 is "non-general" source rock withⅠ-Ⅱ1 organic matter type and high maturity affected by overlying.②General reduced environments with P2l1 as stratified saline water and P2l2 as fresh-brackish water, P2l3 is somewhere in between.beneficial to the preservation of organic matter are indicated by the molecular geochemical characteristics of source rocks. In terms of biological composition, it is proved that there are two characteristic hydrocarbon-generating parent materials in Lucaogou Formation, namely, green algae and cyanobacteria. The former evidence is a biomarker (C28 sterane) related to age, while the latter is the detection of β -carotene and medium-chain monomethyl alkane, Hydrocarbon-generating organisms in different intervals are different with P2l1 and P2l3 mainly composed of aquatic organisms such as bacteria and algae, and cyanobacteria dominate, while P2l2 of high input of aquatic plants(green algae) and terrestrial plants. Differences in water salinity in lake basins are the key factors that affect the bloom of cyanobacteria and green algae in different layers of source rocks.③C30αα- hopane was abundant in P2l1 and P2l2, but is lacking in the source rocks of P2l3, Based on the analysis of different isomerization parameters of sterane and hopane,C30αα/αβ may be a possibe maturity parameter.④the Permian crude oil in Jinan Depression can be divided into three types. Type Ⅰ and Ⅱcrude oils were correspond to the source rocks of P2l1 and P2l2 respectively, and Type Ⅲ crude oil is different to P2l source rocks, possibly correlated tomudstone of Jingjingzigou formation. The research has reference significance for future oil and gas exploration and development in Jinan sag.
Rapid evaluation of the stability of the wedge-shaped hazardous rock mass based on non-contact measurements
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240496
Abstract:
[Objective] With the frequent occurrence of landslide disasters in China, it is indispensable to strengthen the research on unstable rock mass and unstable slopes, due to the inability to quantify or other shortcomings of the traditional analysis methods. In order to improve the traditional scheme, we adopt the non-contact measurement method to obtain and analyse the parameters of wedge-shaped unstable rock mass, and analyse the stability of wedge-shaped unstable rock mass under different working conditions by the obtained parameters. [Methods] Taking the wedge-shaped unstable rock mass in the upper reservoir of a pumped storage power station as an example, this paper reveals the basic features and stability influencing factors of the unstable rock mass based on the fine engineering geological field investigation. A long-distance 3D laser scanning system is used to obtain high-precision point cloud data of the slope. The spatial parameters of the wedge-shaped unstable rock mass are obtained through preprocessing, and the plane where the critical surface is located is also obtained through least-squares fitting to determine the slope angle and slope height of the wedge-shaped body. The point cloud is fitted with local point cloud to determine the normal vector, and the obtained normal vector is calculated to find out the discontinuity occurrence. The Alpha shape method is used to calculate the volume of the unstable rock mass, and the most suitable radius parameter is obtained by comparing with the actual unstable rock mass. Then the limit equilibrium method is used to evaluate the stability of the unstable rock mass. [Results] Through the experiment to get different states of the rock mass capacity, cohesion, friction angle, etc., combined with access to the specification to determine the seismic coefficient and calculation of the geometric parameters, the results show that: in the natural conditions, the wedge-shaped unstable rock stability coefficient of 1.131 is in an essentially stable state; in the rainstorm conditions, the stability coefficient of the wedge-shaped unstable rock body 0.896, in a state of instability; in the seismic condition, the wedge-shaped unstable rock body The stability coefficient of the wedge is 0.917, which is unstable. [Conclusion] In this paper, non-contact measurement and intelligent recognition are applied to the stability analysis of wedge-shaped unstable rock mass, and the overall time taken is 102 minutes, which greatly improves the stability analysis efficiency and reduces the risk of engineering construction.
Probabilistic Stability Analysis of Rock Slope with Coupled Determining and Random Discontinuities
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240388
Abstract:
[Objective] The stability analysis of rock slope is the basis to ensure the normal construction and safe operation of engineering facilities. Once the slope instability occurs, it will cause heavy casualties and economic losses. A large number of determining and random discontinuities widely developed within rock slopes lead to the discontinuity and heterogeneity features of rock mass, and have a significant impact on slope’s stability, deformation characteristics and failure mode. Hence, it is necessary to deeply research the development characteristics of discontinuities and the influence on the stability of rock slopes, which has great theoretical significance and practical value for slope protection and avoiding disaster losses. However, in current studies, the determining discontinuities and random discontinuity networks are rarely taken into account simultaneously to construct rock slope models and to research the effect on the probabilistic stability analysis and failure mechanism of rock slopes. [Methods] In this study, firstly, a three-dimensional numerical slope model is constructed using Rhino software, and the DFN (Discrete Fracture Network) model is applied to generate both determining discontinuities and random discontinuity networks on the basis of the field discontinuity data. Then, the coupling analysis model of determining and random discontinuities was established by integrating the slope model with determining discontinuities and random discontinuity networks within 3DEC software. Afterwards, the probabilistic stability analysis method of rock slopes was proposed to analyze the effect of random discontinuities on slope’s stability. Lastly, to illustrate the effectiveness of the proposed method, a simplified rock slope model is used to assess the impact of random discontinuity networks on slope stability. Additionally, the probabilistic stability analysis of the left bank shoulder slope of Jinping I Hydropower Station is conducted under the natural and excavated slope conditions. [Results]The results indicate that: (1) the proposed method not only effectively and accurately simulates the deterministic and random discontinuity network, but also realizes the coupling modeling of the discontinuity network and rock slope model. (2) The probability distribution diagram of slope stability coefficient can be obtained by the proposed method, and the calculated results are more comprehensive and in line with engineering practice. (3) The random discontinuity network has a more significant influence on slope stability under the excavated slope condition and changes the failure path and instability mechanism of the rock slope. [Conclusion]The research results not only provide references for the excavation and support scheme of rock slopes in engineering practice, but also provide a theoretical basis for the prevention and control of geological disasters.
Application of machine learning models to geothermal groundwater temperature prediction
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240063
Abstract:
Geothermal energy as a kind of clean energy has broad application prospects. The temperature assessment of geothermal water in sustainable development and utilization of geothermal resources is an important research topic. Artificial intelligence technology has become a hot spot and frontier direction in the exploration and development of mineral and oil and gas fields, but in the field of geothermal field development, there are few relevant studies. This paper first analyzes the important value of large data and artificial intelligence application in oil and gas field development, and then introduces the application of artificial intelligence in geothermal field development at present. Taking Xianyang geothermal field in Shaanxi province as an example, the single well geothermal water temperature time series model was constructed by using long and short term memory neural network (LSTM) under the predestined production mode. Random forest and XGBoost algorithm were used to predict the groundwater temperature of multiple geothermal wells. The accuracy of the three models was above 95%, and the running speed is fast. The depth at the top of the water intake section is the primary influencing factor of geothermal water temperature in this area. The model verifies that the fault zone plays an important role in heat storage.The application of the example verifies the superiority of machine learning in solving complex problems in geothermal field development, and the reasonable application of artificial intelligence technology can provide more effective decision-making basis for the efficient development of geothermal field and scientific cost reduction, quality improvement and efficiency improvement.
A Study on Defining the Evolution Stage of Sealing Properties of Fault Zone Filling materials ——Taking the F3 Fault in K1d1 of Beier Depression as an Example
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240302
Abstract:
[Objective] The unreasonable division of the evolution stages of the sealing ability of fault zone filling materials makes it impossible to reasonably explain the differences in oil and gas distribution in different parts of fault traps. [Methods] To solve this problem, in this paper, a research method is established to evaluate and evolve the Closure Index and Cement Index for the fault zone filling material and underlying reservoir rock, and then to comprehensively determine the evolutionary stage of sealing for fault zone filling material by comparing the relative size of the the Closure Index and Cement Index between the fault zone filling materials and underlying reservoir rocks over time. [Results] The method was used to determine the evolutionary stage of sealing of the F3 fault zone filling material in K1d1 of Huhenuoren tectonic belt, Beier Depression, Hailar Basin. The results show that: the fault zone filling materials of the F3 fault in K1d1 are in the stage of non-Closure Sealing and non-Cement Sealing at the measurement points 2,4, 6, 9-11, which is not conducive to the accumulation and preservation of oil and gas in K1n2, resulting in no oil and gas display obtained during oil and gas drilling. The fault zone filling materials of the F3 fault in K1d1 at measurement points 1, 3, 5 are in the stage of Closure Sealing at present. However, due to their evolutionary stage of non-Closure Sealing and non-Cement Sealing during the critical period of reservoir formation, no oil and gas was obtained during oil and gas drilling too. The fault zone filling materials of the F3 fault in K1d1 at measurement points 7、8、12-15 are in the stage of Closure sealing and Cement Sealing, which is most conducive to the accumulation and preservation of oil and gas in K1n2. There are oil and gas accumulation at measurement points 7-8 and 12-15 from oil and gas drilling. [Conclusion] Therefore, the method of determining the evolution stage of fault zone filling material sealing ability is feasible, which is of great significance for determining the sealing ability and formation time of fault traps, and improving the efficiency of oil and gas exploration.
Development Status and Trend Analysis of Physical Simulation Experiments for Geological Hazards
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240454
Abstract:
[Significance] In the past 20 years, physical simulation experiments of geological hazards have developed rapidly, forming an interdisciplinary, widely applied, and rapidly updated development status. Analyzing the current status and trends of physical simulation experiments for geological hazards can help researchers in related fields grasp the industry's current situation, design experiments, develop equipment, and update technologies based on development trends, providing rich and reliable experimental and data for theoretical innovations in geological hazards. [Progress] The paper has conducted extensive research on literature related to physical simulation experiments of geological hazards, and summarized five significances of conducting physical simulation experiments of geological hazards. Then, the research status of the six technologies for geological hazard simulation experiments is analyzed. Model box and flume simulation technology have the characteristics of diverse combinations, low prices, easy installation, and simple operation, and are the most widely used physical simulation technologies for geological hazards. The base friction technology achieves coupling between the simulation model and the gravity field at a low cost, but simulation experiments can only be conducted on two-dimensional slope models. Shaking table and centrifuge simulation technology have high construction and usage costs, but due to their ability to provide vibration and gravity environments for the experimental process, these two technologies are still irreplaceable in geological hazard physics simulation experiments. In situ simulation technology has the drawbacks of long experimental cycles, difficult model production, high personnel input, low automation level, and poor repeatability, but it has significant advantages in avoiding scaling effects, boundary effects, and gravity distortion. [Conclusions and Prospect] The physical simulation experiments for geological hazards are developing towards complex scene construction, large-scale experiments, scientific material selection, and intelligent data collection. This puts higher requirements on experimental technology and economic costs, and there is an urgent need to create a favorable development environment for physical simulation experiments of geological hazards so that physical simulation technology can play a greater role in geological hazard research.
The Transformation of Cr(III) in Different Redox Environments
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240407
Abstract:
[Objective] How Fe(II)-containing clay minerals affect the adsorption-desorption and valence transformation of Cr(III) when the environment is in redox fluctuation deserves in-depth study. [Methods] The adsorption experiments of Cr(III) were carried out by preparing montmorillonite in three different states: oxidized, reduced, and reduced-re-oxidized, to determine the adsorption value, Fe(II)/total Fe, hydroxyl radical concentration, and valence changes, and the montmorillonite solid materials before and after adsorption were characterized by XPS, XRD, and FTIR. [Results] The results showed that the adsorption rate of Cr(III) by oxidized and reduced montmorillonite increased with increasing pH, and reduced montmorillonite had the highest adsorption rate because of the highest Fe content, and no valence change occurred in these two states. The adsorption rate of reduced and reoxidized state montmorillonite was the smallest, which was due to the rapid activation of oxygen by Fe(II) to produce hydroxyl radicals, Cr(III) was rapidly oxidized to Cr(VI), and the lower the pH was, the higher the oxidation rate was, and it was measured at 8h that Cr(VI) was again reduced to Cr(III) again by the reducing substance Fe(II). The high correlation between the consumption rate of Fe(II) and the generation rate of hydroxyl radicals was verified by the change of Fe(II)/total Fe value and hydroxyl radical concentration, which changed the redox environment. [Conclusion] It can be found through the experiment that hydroxyl radicals are generated after reduction and re-oxidation, which affects the adsorption and desorption of Cr(III), and the strong oxidizing hydroxyl radicals can oxidize Cr(III) to toxic Cr(VI), which verifies the assumption that chromium appears to return to the yellowish color after redox fluctuation in the underground environment.
Susceptibility Evaluation of Debris Flows in Gansu Province Based on LA-GraphCAN
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240324
Abstract:
[Objective]The current research on the susceptibility of debris flow disasters has yet to address the limitations of geographic location relationships and spatial dependence. [Methods]This article constructs a debris flow dataset for Gansu Province with 10,198 sample points and proposes a susceptibility assessment method based on LA-GraphCAN. Initially, a nearest neighbor graph is built using KNN based on the cprojection coordinates of sample points. Secondly, GCN is used to efficiently aggregate local neighborhood information and extract key geographic and environmental features. Additionally, GAT is introduced to add a dynamic attention mechanism, enhancing the representation of features. Then ,validate the effectiveness of the proposed method, conduct comparative analyses from different perspectives, and finally, evaluate the susceptibility of debris flows in Gansu Province. [Results]The results indicate that LA-GraphCAN achieves accuracy, precision, recall, and F1 scores of 0.9441, 0.9287, 0.9375, and 0.9331, respectively, outperforming mainstream machine learning models such as Random Forests and CNN. Based on the evaluation of LA-GraphCAN, the number of historical debris flow disaster points in the highly susceptible areas of Gansu Province is 4055, accounting for 95% of the historical debris flow occurrences in Gansu Province, which is consistent with the distribution of historical disasters. [Conclusion]Both the performance evaluation and the susceptibility assessment results for Gansu Province indicate that the LA-GraphCAN method, which considers the spatial dependencies of debris flow disasters, yields superior results and is well-suited for debris flow susceptibility research.
Recognition of structural plane and stability analysis of high steep rocky slope based on 3D point clouds
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230667
Abstract:
Three-dimensional point cloud data of a steep rock slope was acquired using 3D laser scanning technology. After the filtering preprocessing of the point cloud data, the open-source program Discontinuity Set Extractor (DSE) was then used to semi-automatically recognize and classify the point cloud data, obtaining key parameters and clustering information of the slope rock mass structural planes, such as attitude, trace length, and spacing. By fitting the point cloud clustering information, a probability distribution model was created, and a Discrete Fracture Network (DFN) model was established. Further, a three-dimensional block discrete element model of the steep slope was developed using the "Rhino-Griddle-3DEC" integrated modeling method, based on the point cloud data. The model analyzed the stability of slope and potential failure area. The results show that under the gravity condition, the safety factor of the whole slope is about 1.5 and the potential unstable area is the dangerous rock mass located on the top of the slope. Moreover, the structural plane parameters identified by this method can better reflect the engineering properties of the rock mass, providing important guidance for the analysis and evaluation of the stability of steep rock slopes.
Research progress on formation mechanism and reservoir control of Strike-slip Fault-karst oil reservoir
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240149
Abstract:
[Significance] Fault-karst reservoir is widely developed in most basins in China, and its resources are huge, which has become a new hot topic in the field of geography. However, due to the deep burial and difficult exploration of fault-karst reservoir, and it is urgent to form a consensus understanding of trap division, formation mechanism and development control factors. [Progress and Conclusions] Based on literature research, this paper deeply discusses the formation mechanism of fault-karst reservoir. Fault-karst reservoir is a kind of fracture-vuggy reservoir formed in carbonate strata by karstification under the influence of multi-stage tectonic activities. Firstly, the basic concept of Fault-karst reservoir is reviewed. It is pointed out that fault-karst reservoir has the characteristics of deep burial, strong heterogeneity and large difference of fluid properties, and the important role of strike-slip fault in hydrocarbon accumulation and migration is emphasized. Based on the analysis of geological data in Shunbei area and other areas of Tarim Basin, this paper reveals the trap types, formation mechanisms and reservoir-controlling factors of fault-karst reservoir. It is concluded that the segmentation of strike-slip faults, the activity of solution fluid and the timely emplacement of hydrocarbons are crucial to the development of fault-karst reservoir. What's more, the roles of atmospheric fresh water, hydrothermal fluids and hydrocarbon fluids in reservoir reconstruction are also discussed, and how they jointly affect the formation and distribution of Fault-karst reservoir. At last, the paper summarizes the reservoir-forming models of fault-karst reservoir. [Prospects] The discovery and understanding of fault-karst oil reservoir have opened up a new field and direction of oil and gas exploration.
Characteristics of Change in Annual Runoff Volume of Karez in the Turpan Basin in Recent 30 Years
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240094
Abstract:
Karez is an important water conservancy facility in the Turpan Basin.The purpose of this paper is to alleviate the decreasing status of karez , analysing the changing characteristics of annual runoff volume of karez in recent 30 years, which is of great significance for agricultural irrigation, cultural heritage preservation, tourism development and so on. Based on the discontinuous 13 years of annual runoff volume of karez in the study area for the period 1990—2022, as well as year-by-year the exploitation amount of electro-mechanical wells, and water supply from surface water sources, statistical analyses were performed using SPSS 20 software to interpolate missing measurements, and use the trend and mutation analyses to determine their change curves and mutation years. The results of the study indicate: between 1949 and 2023 the number of karez reduced from 1084 to 169,implying that an average of 16 karezs dried up or disappeared each year, while the flow rate declined from 16.11 m3/s to 3.6 m3/s. The correlation coefficients between the annual runoff volume of karez and the exploitation amount of electro-mechanical wells, the amount of water supplied by surface water sources, the irrigated area and precipitation were -0.890, -0.149, -0.660, and 0.764. Through the construction of a model of the relationship between the annual runoff volume of karez and the exploitation amount of electro-mechanical wells and the amount of water supply from surface water sources, and the average relative error between the measured value and the predicted value was 1.8%, which effectively solved the problem of missing data. In addition, the exploitation amount of electro-mechanical wells and the amount of water supplied by surface water sources as a whole showed a fluctuating upward trend, and the annual runoff volume of the karez increased and changed abruptly in 2006, the reasons for the sudden change might be related to the government's implementation of regulations for the protection of karez. Therefore,in view of the important cultural and engineering value of karez , make greater efforts in the future to protect it and promote the sustainable use of water resources and high-quality development in the Turpan Basin.
Characteristics of oil shale development and paleoenvironment restoration of Jurassic Yan’an Formation in southwestern Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240171
Abstract:
[Objective]There are many sets of oil shale associated with coal and non-associated oil shale in the Jurassic Yan’an formation in the southwest of Ordos Basin, but the study on the characteristics and sedimentary environment of oil shale in this area has been relatively lacking for a long time. [Methods]Based on the oil shale samples from wells in the study area, the industrial index, geochemistry characteristics and sedimentary paleoenvironment of oil shale were studied by low-temperature retorting, rock pyrolysis, major and trace elements measurement and gas chromatography. [Results]The oil shale in study area oil-bearing ratio is 3.8% ~ 6.7%, the ash is 49.46% ~ 75.58%, the total sulfur is 0.31% ~ 2.29%, and the calorific value is 11.95 kJ/g (average value). The logging curves show the characteristics of high gamma, high resistivity and low natural potential, which is obviously different from coal bed and mudstone. The main type of organic matter was II2. The abundance of organic matter is high, and the whole is in the stage of immature-low maturity. It belongs to middle quality, siliceous ash and extra low sulfur oil shale. The main elements in the oil shale are SiO2 and Al2O3, which are 48.26% (average) and 17.57% (average) and the micronutrient Sr, Th, and U were enriched, and Ni, V, and Ba were depleted, indicating that there were more potassium-containing minerals and higher stable components in the study area. [Conclusion]Based on the analysis of paleoenvironmental element markers and saturated hydrocarbon chromatography, it is considered that the organic matter mainly comes from the mixed organic matter, ancient productivity is medium and the sedimentary environment is unique, which belongs to the warm and humid continental fresh water depression environment. The analysis of environmental factors shows that the redox condition is the main influencing factor of organic matter enrichment and the sedimentary model of oil shale evolution in Yan’an formation in different depositional periods is established. The research results provide important theoretical guidance and technical support for the oil shale exploration and development of the Jurassic Yan’an formation in the southwestern margin of Ordos Basin.
Ddeformation history analysis and movement process simulation debris flow in Sanggu Valley Glacier debris flow in southern Tibet
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240172
Abstract:
Abstract:The glacial debris flow in the Yarlung Zangbo River basin in southeastern Tibet is large in scale, long in duration and strong in impact. This study on the deformation characteristics and influencing factors of the Sanggugou debris flow will provide a scientific reference for the prediction, early warning and prevention of glacial debris flow disasters in southeastern Tibet. As it is difficult to quantitatively describe the formation mechanism of large-scale debris flows using traditional methods, this paper reveals the relationship between the outbreak of Sanggugou debris flows and factors such as material sources and rainfall based on on-site surveys of debris flows in the Sanggugou Basin, drone aerial photography, satellite image information, and geological and meteorological data. A method combining InSAR and RAMMS technology to comprehensively analyze the material source deformation analysis before the debris flow outbreak and the movement characteristics of the debris flow during the outbreak is proposed. First, based on the SBAS-InSAR technology, the deformation of the Sanggugou debris flow during the two outbreaks was analyzed. Combined with satellite images, drone images, and on-site surveys, the deformation process inversion and disaster trend prediction before the outbreak of historical geological disasters in Sanggugou were achieved. Through deformation monitoring and analysis, it was found that the material sources at the rear edge of the debris flow formation area gradually moved to the front edge due to the infiltration of rainfall, revealing its development process under the action of hydrodynamics. The RAMMS debris flow numerical simulation software was used to simulate the movement process of the Sanggugou debris flow during the outbreak. According to the accumulation depth and flow velocity of the debris flow under asynchronous time conditions, the evolution process of the study area was divided into three stages: initial movement, acceleration movement, and deceleration-final. This method combines the deformation history analysis of glacial debris flow with the simulation of the movement process to provide a scientific basis for the development trend and prediction of debris flow, and provide a reference for engineering prevention and control design.
On site full-scale test of pull-out resistance mechanism upon transmission line anchor foundation
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240221
Abstract:
In order to study pull-out resistance mechanism of the transmission foundation, the full-length bonded anchors were chosen as the research object which are commonly used in transmission line project, and the granite ground in Quanzhou was selected as the test site. Three field full-scale tests were carried out on single anchors, while four tests were performed on group anchors, where the displacement sensors were used to monitor the foundation and ground deformation, and the optical frequency domain reflectometry (OFDR) was used to record the anchor rod strain. The results show that the load-displacement curve of single anchor is different from that of group anchors, and the plastic deformation is more obvious on group anchors than that in single anchors. At the beginning of the test, the displacement of the anchor system mainly depends on the anchor bar tension, while the slippage on anchor rock interface contribute more to the displacement of the anchor system at the end of the test. The axial tension stress of anchor rod gradually decreases with the depth and eventually approaches zero at 2~3m in depth. The typical shear failure of anchor-rock interface was observed during the pull-out test of test anchor bolt. The ultimate bearing capacity is determined by the failure principle of anchor bar yield. In addition, the anchor rock bond strength of the test site by calculating the axial tension stress of anchor rods with different cross-sections is 1467kPa, which is consistent with the recommended value of the Industry Standard DL/T 5219. The achievement can provide a reference basis for engineering design under similar bedrock conditions.
Pressure evolution and weak low pressure genesis of Shanxi Formation sandstone reservoir in Xinzhao area, northern Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240130
Abstract:
The Upper Paleozoic sandstone reservoirs in Xinzhao area, northern Ordos Basin are rich in natural gas and generally develop abnormal low pressure. The understanding of paleo-pressure evolution and current subnormal pressure formation mechanism is not very clear, which constraine the understanding of tight sandstone gas accumulation and increase of natural gas reservoir and production. In this paper, the petroleum charging history in the second member of Shanxi Formation was comprehensively analyzed by means of fluid inclusion petrographic observation, micrometry and laser Raman analysis, and the paleo-pressure in the key period of reservoir formation was obtained. The paleo-pressure evolution history was recovered by basin simulation method, and the coupling relationship between paleo-fluid pressure evolution and petroleum charging was established. The relationship between the causes of subnormal pressure and tight gas accumulation is further discussed. The results show that: (1) CO2 was captured in the second member of Shanxi Formation in Xinzhao area from 170 to 180Ma, when the source rock was in the middle to low maturity stage, and the methane inclusion was captured in the peak of hydrocarbon generation from 138 to 121Ma. (2) The overpressure in the second member of Shanxi Formation began to develop in the early Jurassic, and reached the maximum in the end of the Early Cretaceous. The paleo-pressure and paleo-pressure coefficient were about 50MPa and 1.31 respectively. (3) Due to temperature decrease, pore rebound and gas diffusion, the decrease of formation pressure in the second member of Shanxi Formation accounted for 49%, 14.5% and 36.5% of the total formation pressure, respectively. The tight gas reservoir of the second member in Shanxi Formation has undergone the evolution process of normal pressure-medium overpressure-normal pressure and low pressure. Hydrocarbon generation supercharging and pressure conduction are the main reasons for the formation of ancient overpressure. Temperature drop and natural gas diffusion are the main factors for the formation of abnormal low pressure in the second member of Shanxi Formation.
Provenance Analysis of Benxi Formation in Yanchang Exploration Area of Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240191
Abstract:
The source of detrital material is one of the important factors controlling the development and distribution of the Benxi Formation sandstone reservoir in the Yanchang exploration area. On the basis of previous research, this article conducted four methods for the source analysis of the Benxi Formation, including detrital zircon age, heavy mineral combination types, trace elements, and sandstone gravel size statistical analysis, on sand and mudstone samples from 37 wells in the Yanchang exploration area. The peak ages of 1912 Ma and 2425 Ma in the exploration area correspond to the northern edge of the North China Craton, while the peak ages of 435-447 Ma and 952-976 Ma in the remaining five wells correspond to the peak ages of the North Qinling Mountains. Based on this, the sources in the exploration area can be divided into two directions: north and south; In the analysis of heavy mineral combination types, the southwest region has a higher content of zircon and tourmaline, while the southeast region has a higher content of rutile. Therefore, the southern source can be further divided into two directions: southwest and southeast; Corresponding to the analysis results of heavy minerals, in the analysis of trace element zirconium niobium ratio, there are two directions of material sources in the southwest Longdong region and the southeast Yuxi region; Finally, by analyzing the distribution characteristics of sandstone gravel diameter on the plane, it is shown that there are sources from the southeast direction in the study area. Through comprehensive analysis, it can be concluded that the Benxi Formation in the Yanchang exploration area can be generally divided into three source areas: northeast, southwest, and southeast, indicating the erosion areas in the northern margin of the basin, the southern margin of the Qilian Mountains, and the eastern section of the North Qinling Mountains. Among them, the southeast source area is the thickest and closest to the Yanchang exploration area. This achievement has identified three directions of material sources and their influencing areas within the study area, which has important reference significance for predicting the distribution of sand bodies and dividing sedimentary facies in the Yanchang Benxi Formation gas field.
Simulation Research on the Formation Mechanism of Hydrochemistry in the Beishan Preselected Area for Geological Disposal of High-level Radioactive Waste in China
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240194
Abstract:
Hydrochemical characteristics play a pivotal role in the site selection and long-term safety assessment of high-level radioactive waste (HLW) disposal repositories. This study utilized integrated hydrogeochemical analysis and modeling to examine the general hydrochemical characteristics, horizontal zoning, and formation mechanisms of hydrochemical characteristics in different hydrogeological zones of the Beishan area in Gansu, China, considering it as a preliminary site for HLW disposal. The results indicated that the predominant hydrochemical types were Cl·SO4-Na and SO4·Cl-Na, with pH values mostly ranging from 7.5 to 8.3. The bedrock groundwater was generally undersaturated with respect to minerals such as halite, gypsum, fluorite, glauconite, and feldspar, while it was often oversaturated with respect to clay minerals. There was a clear horizontal zonation of hydrochemical characteristics from the recharge area to the discharge area. Mazongshan site was the main regional recharge area with low mineralization, where the formation of hydrochemical components was primarily controlled by leaching processes. Sedimentary basins were the discharge areas with high mineralization, where hydrochemical components were mainly influenced by evaporation. The water–rock interaction processes along the flow path were mainly driven by the dissolution of halite and gypsum, with minimal impact on silicates. Overall, the hydrochemical formation of bedrock groundwater in the Beishan area was predominantly governed by evaporation and interaction processes. This research provides important support on hydrochemistry for the site selection of the HLW disposal repository.
Astrocycle Identification and High Sedimentation Rates Sedimentary Filling Response Characteristics in the YingXiongLing Shale of Westren Qaidam Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230492
Abstract:
Abstract:The exploration and development potential of YingXiongLing shale oil in the Qaidam Basin is huge, but the work on Cyclostratigraphy is relatively weak at present, This article conducts a spectral analysis of four wells in the upper section of the Lower Ganchaigou Formation, which is developed in the YingXiongLing shale, Based on the results of core analysis, logging, and geochemical analysis, multiple sets of Milankovitch cycles in this set of strata have been identified, Based on 404.858ka long eccentricity period, the "floating" astronomical scale of YingXiongLing shale is established. It is estimated that the sedimentary time of the upper member of the Lower Ganchaigou Formation is 4.86Ma, and the average sedimentary rate is 340.44m/Ma, It has been clarified that high sedimentation rate is one of the important characteristics of the YingXiongLing shale. The sedimentary response characteristics of Total organic carbon content based on the long eccentricity period analysis show that the organic carbon enrichment degree of the YingXiongLing shale in the Qaidam Basin is controlled by the sedimentary rate, With the increase of deposition rate, the content of Total organic carbon increases. When the deposition rate exceeds 450m/Ma, Total organic carbon decreases significantly due to the dilution effect of debris. The sedimentary structure response model established based on the precession period found that when the precession parameter is at the minimum value, the main development is poor organic matter layered limestone, while when the precession parameter is at the maximum value, the main development is rich organic matter Laminated limestone. The obvious orbital forced response exhibited by the YingXiongLing shale will help predict favorable sections of shale oil and provide some new ideas for efficient exploration and development of YingXiongLing shale oil in the future.
The characteristics、disaster mechanism、prevention and treatment and enlightenment of airport high fill landslide in mountainous area—Take Panzhihua Airport as an example
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240216
Abstract:
With the rapid development of China's transportation industry, numerous regional airports have been constructed in mountainous regions across the country. Due to the special engineering geological environment conditions, a large number of high fill slope projects have been produced, and the biggest problem faced by them is the deformation control and long-term stability of high fill slope in the operation stage. Taking Panzhihua Airport as an example, based on the systematic review of the geological disaster history during the construction period and operation period, the development characteristics of three typical high-fill landslides during the operation period were described in detail, and the causes and evolution mechanism of high-fill landslides were analyzed. Finally, the key technology of landslide control was proposed. The results show that: (1) The internal causes are the topography and landform that is conducive to the accumulation of surface water and the special slope body structure that is conducive to rainfall infiltration. Rainfall concentration and short-time rainstorm are frequent, and the groundwater is abundant and easy to be enriched in the relative water barrier layer;(2) The instability evolution mechanism of the high fill slope of Panzhihua Airport can be summarized as follows: long-term infiltration of heavy rainfall - rise of groundwater - softening of soil on the weak surface of foundation cover section and attenuation of shear strength - push creep - failure of retaining structure - progressive slip shear - overall slide; (3) This kind of high fill landslide should be treated with the idea of anti-sliding strong support and retaining combined with drainage groundwater. The research results can be used as reference for the research of deformation mechanism and deformation control technology of other high fill projects.
Study on hydrogeochemical characteristics and genesis of Jiusuo geothermal field in southwestern Hainan
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240242
Abstract:
Abstract: Hainan Island possesses abundant geothermal resources; however, the previous geothermal explorations has primarily focused on production, neglecting research into the origins of geothermal water chemistry, the water-rock interactions, multiple methods for evaluating thermal reservoir temperature, the formation mechanisms of geothermal fields, and so on. [Objective]Building upon the existing exploration data, this paper conducts a in-depth analysis to enhance our understanding of genetic mechanism of the geothermal field and to offer valuable insights for the development of geothermal fields.[Methods]By utilizing the ratios and correlations of major ions, piper diagrams, F- concentration distribution maps, silica-enthalpy and SiO2 mixing model graphs, silica-enthalpy equations, δD-δ18O of water along with GMWL curves, this study focuses on the geothermal water of Jiusuo to deeply analyze the sources of chemical components, the cation exchange processes, the origin of F-, the most probable reservoir temperatures, and the circulation depths of the geothermal water, thereby proposing a conceptual model for explaining genesis of the field.[Results]The findings show that the geothermal water hydrochemistry in the study area is mainly of the SO4·HCO3-Na type, with Ca2+ and Mg2+ replacing Na+ and K+ in the rock. The primary source of SO42- is sulfide oxidation in andesite and rhyolite. The dissolution of minerals such as mica, amphibole, and fluorite, ion exchange, and alkaline environment are the controlling factors for the concentration of F-.The chemical composition in the geothermal water is predominantly influenced by silicate mineral dissolution, ion exchange processes, as well as the degree of development of geological strata and structures. It is most likely that when mixed with cold groundwater, the temperature range of geothermal water in this area falls between 99 °C to 169 °C; with cold groundwater mixing accounting for 80% to 93%, while approximately 10% steam loss occurs before mixing cold groundwater. The depth at which geothermal water circulates ranges from 1.8 to 3.8 km. [Conclusion] The conceptual model of geothermal origin indicates that the geothermal water in the Jiusuo geothermal field originates from rainfall recharge and flows under the control of the Furongtian-Wangxia structural belt, Ledong-Xichang structural belt, and the Jiusuo-Lingshui deep fault. It flows from the granite area to the andesite and rhyolite areas, where it absorbs energy from radioactive decay in the granite and a small amount of possible mantle-derived thermal energy. This process leads to heating up, silicate mineral dissolution, cation exchange, sulfide oxidation, and resulting in increased concentrations of fluoride ions (F-), sulfate ions (SO42-), and other chemical components in water. These processes cause an evolution in water chemical type. Due to the increase in temperature, the density and viscosity of geothermal water decreases, pressure increases, so buoyancy is generated. Driven by both hydraulic gradient and buoyancy gradient, geothermal water ascends along the Jiusuo-Lingshui deep large fault zone and rock fractures in the subsurface. It then mixes with cold groundwater in the shallow subsurface of the study area before being buried in the Quaternary and Tertiary sedimentary cover layers, ultimately forming a geothermal field. Is there mantle-derived thermal energy in the deep region of geothermal fields in southwestern Hainan? Presently, there is insufficient evidence to substantiate this assertion. This is a scientific inquiry that warrants further investigation.
Optimization of 4D Hydrogeological Processes Monitoring Through Cross-hole Electrical Resistivity Tomography (CHERT) using Bayesian experimental design
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230600
Abstract:
(Objective) The geophysical method can effectively monitor the dynamics of water flow and material transport in 4-D hydrogeological processes, and its imaging accuracy is often closely related to the monitoring scheme. Taking the commonly used Electrical resistivity tomography (ERT) as an example, in order to obtain good imaging accuracy, a large number of electrode arrangements are often required, which leads to a long monitoring time and therefore cannot timely respond to the 4-D hydrogeological dynamic process. Most of the existing ERT monitoring scheme optimization studies focus on surface ERT, and few focus on cross-hole ERT. (Methods) Since cross-hole ERT has more advantages in the high-precision characterization of the study area, this study proposed to optimize the monitoring scheme of cross-hole ERT by Bayesian experimental design. By comparing the measurement time and accuracy of the optimized electrode arrangement with the traditional electrode arrangement through indoor static/dynamic tests and field sites, the validity of the optimization scheme of Bayesian experimental design was verified. (Results) The laboratory test results showed that the optimized monitoring scheme could reduce the measurement time by about 75%, and the inversion results of the optimized scheme could more accurately depict the dynamic resistance anomaly region, significantly improving the hysteresis error of the traditional scheme monitoring the 4-D hydrogeological process. Field test shows that the optimized scheme can reduce about 95% monitoring time under the premise of ensuring monitoring accuracy. (Conclusion) Optimizing the monitoring scheme of cross-hole ERT electrode arrangement based on Bayes experiment design provides technical support for efficient monitoring of 4-D hydrogeological processes.
Development and application of a novel ring shear apparatus
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230340
Abstract:
The total stress, pore water pressure and effective stress of the sample can be obtained by developing a new ring shear apparatus for measuring and controlling pore water pressure, and the stress-strain-pore water pressure characteristics of the sample can be effectively revealed. In this paper, the self-developed automatic ring shear apparatus can control the drainage conditions, and realize the control of pore water pressure during the ring shear process, and measure the pore water pressure, sample drainage volume, torque and axial displacement. Taking the slip zone soil of Huangtupo landslide as an example, the consolidated drainage ring shear test, consolidated undrained ring shear test, variable pore pressure ring shear test and constant head permeability test were carried out respectively. The test results show that the ring shear chamber can withstand 0~1000kPa pore water pressure by using side seal and top and bottom tee valve. When the inlet valve at the bottom of the lower ring shear box is opened and the volume pressure controller is connected, the pore water pressure can be controlled and the volume of drainage or absorption of the sample under a certain pore pressure can be measured with a measuring range of 0~200cm3. When the outlet valve at the top of the upper ring shear box is opened and the pore water pressure sensor is connected, the pore water pressure inside the sample under undrained conditions can be measured with a range of 0~1000kPa. During the test, the shear dilatancy or shear contraction was measured by the axial displacement sensor with a measuring range of 0~10mm. The ring shear force is measured by a torque sensor with a range of 0~300N·m. In addition, the influence of dynamic change of pore water pressure on ring shear strength and the change of sample permeability coefficient during consolidation or ring shear can also be tested with the new ring shear apparatus. A novel ring shear instrument can accurately carry out mechanical tests of specimens under large deformation and different pore pressure conditions to provide technical supports for revealing the evolution mechanism of pore water pressure during long distance landslide sliding.
Discussion on the spatial and temporal difference of Cenozoic rift formation and evolution and its genesis mechanism in the Pearl River Estuary Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240054
Abstract:
To deepen the understanding of the temporal and spatial differences. In the this study is based on the seismic profile data of the the Pearl River Mouth Basin, using the methods of structural analysis, balanced profilerestoration and fault activity rate calculation, the fault system and structural evolution process of the the Pearl River Mouth Basin are analyzed. Moreover, the. causes of structural differences in the depressions in this Basin are explored in combination with the pre-existing structure, basement characteristics and dynamic background of the basin. The main results are as follows: The basement pre-existing structures in the Pearl River Mouth Basin mainly developed a series of NE trending thrust faults and the conjugate NW trending pre-existing thrust fault system; The faults in the Pearl River Mouth Basin show NE, NEE, near EW and NWW strike from west to east, controlling the tectonic framework of the basin during the rifting period; The evolution stages of the basin are divided into four stages: the early stage of rift (E1sh-E2w), the development stage of rift (E3e), the depression stage (E3z-N1z-N1h), and the tectonic activation stage (N1y-N2w-Q); The fault system in the basin mainly exhibits a clockwise transition from NE-NEE extensional properties to nearly EW-NW extensional strike slip properties. This is due to the long-term inheritance and development of some main faults along the basement pre-existing faults during the rift period. At the same time, the differences in basement pre-existing structures and lithology result in different tensile and shear strengths, as well as being controlled by peripheral plate movement, magmatism, and regional stress field changes. The rift structure of the basin has undergone a transformation from north to south, from narrow and narrow grabens and semi grabens with "thick below and thin above" characteristics to wide and gentle grabens and semi grabens with "thick above and thin below" characteristics. The distribution of sedimentary centers in the basin shows a migration pattern along the NE direction.
Geochemical analysis of Ordovician natural gas in Shunbei area of Tarim Basin and its exploration significance of oil and gas
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240099
Abstract:
After years of exploration, oil and gas breakthroughs have been made in the strike-slip fault zones in the northeast of Shunbei area, forming hydrocarbon types and phase distribution patterns characterized by oil reservoirs in the north, condensate gas reservoirs in the south, and dry gas reservoirs in the east. Therefore, it is of great significance to discuss the genesis mechanism, source and thermal maturation of the gas from the perspective of the overall oil and gas distribution for the further continuous promotion of ultra-deep oil and gas exploration. By systematically collecting gas samples from different fault zones, this study analyzes the geochemical characteristics of natural gas in Shunbei area in detail. The results show that the natural gas in Shunbei area is less affected by TSR, except that there is strong modification by thermal-chemical sulfate reduction (TSR) in the part locations of the fault zones. The natural gases in the No. 1 fault zone and in the northern and middle sections of the No. 5 fault zone are mainly the crude oil associated gas from the primary kerogen cracking, while the natural gases in the southern section of No. 5 fault zone and No. 4 fault zone are mainly the mixture of early kerogen cracking gas (oil-associated gas) and late crude oil cracking gas. The natural gas in Shunbei No. 12 fault zone originated from deeper high-temperature crude oil cracking gas, and the crude oil cracking grade has reached wet gas cracking. The natural gases in the study area mainly comes from the source rocks of the Lower Cambrian Yurtus Formation, and the parent material of gases has the characteristics of benthic algae or mixed source of benthic algae and planktonic algae. Finally, the regression equation of thermal maturity calculation based on carbon isotope of methane is established during the process of hydrocarbon generation in the source rocks of Yurtus Formation. The research results can provide important reference for the next ultra-deep gas origin, source and thermal maturity analysis.
Identification of nitrogen pollution sources, migration and transformation processes in shallow groundwater system of Caidian, Wuhan
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230357
Abstract:
【Objective】In recent years, with the continuous intensification of human activities, groundwater nitrogen pollution has become a typical environmental problem worldwide. In order to identify nitrogen pollution sources, contribution ratio, migration and transformation characteristics of shallow groundwater, Fourteen surface water, Twenty Four shallow groundwater and Seven soil samples were collected from the main water supply area of Caidian District, Wuhan City, Hubei Province, their water chemical indexes, nitrogen isotopes, hydrogen and oxygen isotopes, etc. were tested and analyzed.【Methods】 Based on the local land use type, water chemistry and δ15N-NO3-、δ18O-NO3- double isotope tracer technology were integrated to identify the nitrate nitrogen pollution sources and their migration and transformation rules in groundwater in the study area, and the Iso-Source model was further used to quantitatively identify the contribution proportion of different nitrogen pollution sources.【Results】 The types of regional nitrogen pollution were mainly nitrate nitrogen, among which about 66.7% of the NO3- concentrations in groundwater sampling points exceeded the WHO limit (10mg/L), Nitrification of sewage and manure, soil organic matter and ammonia-containing fertilizers is the main sources of NO3-,, and the average contribution rates of nitrate nitrogen to shallow groundwater were 48.6%, 32.9% and 18.5%, respectively, which were affected by obvious human activities. Further combination of regional water chemistry and hydrogen-oxygen isotopic composition showed that the morphological transformation of regional surface water and groundwater nitrogen was mainly affected and controlled by nitrification. 【Conclusion】The research results will provide a theoretical basis for further understanding of nitrogen cycling process and nitrogen pollution control in Caidian District.
Research on Comprehensive Evaluation and Utilization of Selenium-rich Land Quality in Tunliu District, Shanxi Province, China
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230666
Abstract:
Carrying out land survey and evaluation and developing characteristic industries is an important work to realize rural revitalization and consolidate the results of poverty alleviation. In order to more accurately and effectively guide the regional agricultural production layout and the development of specialty industries, this paper selects the indicators of selenium-rich industry quality, ecological environment and arable land strength to construct a comprehensive quality evaluation system of selenium-enriched land, and carries out selenium-enriched land evaluation in Tunliu District, Changzhi City, Shanxi Province. Fuzzy mathematical method, entropy weight method and comprehensive index method were applied to evaluate and classify the land. The results show that: ①54.47% of high selenium and selenium-suitable soils in Tunliu District are concentrated in the eastern part of the district; the distribution of arable land strength grade is uneven, with the whole being low in the west and high in the east; and the ecological condition of the whole region is clean. ②The area of first-class selenium-rich land in the region is 299.33 square kilometers, accounting for 26.61%, concentrated in the eastern plains. ③Wheat, sharp pepper and green pepper in Tunliu District have reached the standard of selenium enrichment, and the rate of selenium enrichment of sharp pepper is 100%, and the crops are in good clean condition. Based on the evaluation results, combined with the territorial spatial planning of Tunliu District, three types of land are divided: Class A land (selenium-enriched and fertilized and clean) is planned for planting selenium-enriched wheat and green vegetables, and at the same time, developing tourism agriculture; Class B land (selenium-appropriate and clean) is planned for planting selenium-enriched peppers, and at the same time, developing deep-processing of agricultural products; and Class C land (not selenium-enriched and fertilized) is built to create a system of deep-processing of agricultural products, and at the same time, developing agricultural trade and tourism. This paper provides theoretical support and scientific suggestions for the planning of selenium-enriched agriculture industry in Tunliu District as well as regional synergistic development.
Infrasound warning model for debris flow in typical drainage basin of Beijing mountainous area
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240223
Abstract:
[Objective] Infrasound is an effective debris flow warning approach. The threshold warning method commonly used in previous studies considered only individual infrasound characteristics, which can result in inaccuracies in debris flow warning. [Methods] Infrasound data collected in Caodianshui village, Beijing, was employed to investigate the differences between infrasound characteristics of debris flow and environment background. Based on random forest algorithm, the infrasound warning model for debris flow was established. [Results] The effective pressure of debris flow infrasound ranges from 0.4 to 1.0Pa. In contrast, the effective pressure of environmental infrasound is mostly lower than 0.1Pa, but it can exceed 0.4Pa due to noise. The energy of noise infrasound concentrated in frequency band below 6Hz. The energy of debris flow infrasound in 6-15Hz is significantly higher than that of noise infrasound. Therefore, comprehensive time-frequency characteristics, especially the energy in 6-15Hz, should be taken into consideration to identify debris flow infrasound. By taking effective infrasound pressure, effective infrasound pressure of 6-15Hz, zero crossing rate, main frequency and amplitude of main frequency as characteristic variables, the debris flow infrasound warning model based on random forest was constructed. The AUC of the model was 0.99. The test data recognition accuracy reached 90%, which is 15% higher than that of the traditional threshold method. [Conclusion] This study demonstrate that the infrasound warning model for debris flow based on random forest algorithm can significantly improve the warning accuracy and is applicable to the typical basin in Beijing mountainous area, which can also provide a reference for the debris flow infrasound warning research in other areas.
Reconstructing Sonic Well Log Curves based on Machine Learning and Analysis of Model Interpretability
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230504
Abstract:
Abstract: (Objective)Well logging technology is a critical means for determining subsurface lithological characteristics and geological structures, playing a pivotal role in the petroleum exploration industry. However, issues such as instrument damage and wellbore conditions frequently lead to data gaps and incomplete curves in well logging. Traditional multivariate linear regression and empirical formula methods fail to construct a reasonable relationship model among well logging curves, resulting in relatively low curve reconstruction accuracy. Although machine learning algorithms are able to find the most appropriate data mapping relationship between a large amount of data and thus improve the model accuracy, the black-box model constructed by them cannot be well explained in comparison. (Methods) In this paper, the Support Vector Regression (SVR), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost) are used to compare with the traditional Multiple Linear Regression (LR) to reconstruct the acoustic logging curve of the NDR well 22-30b-11 and the XGBoost model is interpreted based on the Shapley Additive Explanations (SHAP) algorithm. (Results)The results demonstrate that XGBoost outperforms SVR and RF on the test set, achieving R2 values of 0.996 and MSE of 6.371, surpassing SVR with R2 of 0.990 and MSE of 15.755, and RF with R2 of 0.993 and MSE of 9.871. In contrast, the LR method yields an R2 of 0.969 and MSE of 48.895, indicating that XGBoost exhibits higher accuracy and better generalization performance in reconstructing acoustic time difference curves. This paper innovatively adopts the SHAP algorithm to explain the XGBoost black-box model, showing that when selecting important features for model construction, the XGBoost model adopts formation temperature data as important features significantly more reasonable than the well logging data adopted by the multiple linear regression scheme. Finally the model is interpreted based on SHAP for single point and global feature interactions. (Conclusion)The above results show that the machine learning algorithm is significantly better than the traditional multiple linear regression method in logging curve reconstruction, and prove the feasibility of SHAP algorithm in the interpretation of machine learning model for logging curve reconstruction, which provides a new idea for the subsequent development of machine learning in logging technology.
FDEM simulation study on deterioration characteristics of weak-hard interbedded strata landslide-anti-slide pile system under wetting-drying cycles
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230700
Abstract:
[Objective]In Zigui Basin of the Three Gorges Reservoir region, prone-sliding strata mainly composed of weak-hard interbedded strata are widely distributed. Under the action of long-term reservoir water immersion, erosion and rainfall, the formation rock and soil bodies deteriorate and become an important internal cause of reducing landslide stability and affecting project safety. [Methods]Taking rock and soil mass of weak-hard interbedded strata as the research object, fi-nite discrete element method (FDEM) is used to calibrate the mechanical properties of hard and soft rocks in the weak-hard interbedded strata under different wetting-drying cycles. Then the mesh is redivided by the improved Tyson poly-gon program, and the embedding function of zero thickness cohesive force unit is realized. The FDEM numerical model of landslide-anti-slide pile system in weak-hard interbedded strata formation is proposed and established. Finally, the formation process of landslide cracks and the embedding mechanism of anti-slide piles under different wetting-drying cycles are studied. [Results]The results show that: ① The number of simulated landslide cracks increases with the in-crease of the number of wetting-drying cycles, and the cracks width also increases gradually. The results of simulation are basically consistent with those of the site of Majiagou landslide; ② The simulated cracks of the landslide-anti-slide pile system show two evolutionary patterns: one is that the cracks spread downward from the rock mass on the top side of the pile along the pile body; the other is that the cracks gradually extend from around the anti-slide pile to the inside of the slide body, connecting with the transverse cracks and vertical cracks, and finally forming large through cracks; ③ When the number of wetting-drying cycles increases, the horizontal displacement, bending moment and shear force of anti-slide pile also increase; ④ The cracks in the weak-hard interbedded strata bedrock of the anti-slide pile have the characteristics of localized development, and with the increase of the number of wetting-drying cycles, the stress in the region gradually decreases, the displacement and strain gradually increase, and the corresponding cracks become more and more intensive. [Conclusion]The results of this study can provide support for the prevention and control of land-slide in weak-hard interbedded strata under different wetting-drying cycles.
Susceptibility evaluation of debris flow in Bomi-Metuo area based on Pearson Chi-square test algorithm
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240091
Abstract:
The complex geomorphic units and active geological structures in Tibet provide a good breeding environment for debris flow in the region, but also pose a great threat to human life and property. The evaluation of debris flow susceptibility can identify key areas for disaster prevention and reduction in the region. Taking Bhumi County and Medog County of Tibet Autonomous Region as the study area, 12 factors with high influence on debris flow, including elevation, slope, stratigraphic lithology and rainfall, were selected by Pearson Chi-square test algorithm as evaluation indexes, and 282 debris flow points and non-debris flow points in the study area were taken as sample database. Based on ArcGIS platform, four susceptibility evaluation models were established by using information method and machine learning method, and ROC curve and AUC index were introduced to evaluate the susceptibility accuracy of debris flow. The results show that: (1) Considering the different types of debris flow in different dimensions and the different controlling factors, the normalization coefficient of latitude and air temperature is used as the evaluation index of debris flow susceptibility, which can eliminate the excessive response of debris flow to temperature in low altitude areas to a certain extent. (2) Air temperature, distance from water system, distance from road, formation lithology and elevation are the main factors of debris flow occurrence in the study area; Factors such as vegetation coverage, terrain humidity, and slope also play an important role. (3) Considering the relationship between the disaster point of debris flow and the classification attributes of the impact factors, the classification attributes of the impact factors were assigned scores and trained as input features. The prediction effect of the machine learning model was good, and the average AUC was 0.980, which was better than the traditional information model on the whole. (4) The AUC of SVM model is as high as 0.987, the FR value of the highly prone region is 41.13, and the prediction area of highly prone regions takes up the smallest proportion, so it has the ability to perform high-precision prediction in large-scale regions.
Experimental Study on Dynamic Impact Compression Characteristics of Sandstone under Freeze-thaw Cycles
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240103
Abstract:
In order to study the effect of freeze-thaw cycles on the microstructure and dynamic mechanical properties of sandstone, nuclear magnetic resonance testing, electron microscope scanning and dynamic impact compression tests with impact velocities of 3, 6 and 9 m/s were carried out on sandstone with freeze-thaw cycles of 0, 30, 60, 90 and 120 times, respectively. The results show that the dynamic mechanical properties of sandstone deteriorate with the increase of freeze-thaw cycles at the same impact velocity. All dynamic mechanical properties have rate-dependent effects. In addition, the dynamic peak stress index attenuation model of freeze-thaw sandstone is established, and it is proved that the impact velocity can compensate the damage and deterioration of freeze-thaw cycle to a certain extent, which can reduce the attenuation constant and prolong the half-life of freeze-thaw sandstone. The dynamic impact failure mode of freeze-thaw sandstone is as a whole crushing failure. With the increase of freeze-thaw cycles and impact velocity, the fragmentation degree of sandstone increases, the fragment scale decreases, the fragment quantity and powder proportion increase, and the fractal dimension increases. Based on the above tests, the damage mechanism of sandstone under the action of freeze-thaw cycle is explored, and it is found that frost heave damage is the main cause of freeze-thaw damage of sandstone. With the increase of freeze-thaw cycles, the internal damage degree of sandstone intensifies, the bonding effect between mineral crystals and cementing materials weakens, the pore size and number increase, and even intergranular cracks and transgranular cracks appear. This study can provide relevant reference for rock engineering in cold area
Rockfall damage evaluation and treatment suggestions of mountain highway based on kinematics three-dimensional simulation
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240068
Abstract:
[Objective] The three-dimensional simulation of kinematics considering the characteristics of slope topography is an important basis for the evaluation of dangerous rocks collapse in mountainous highways, and its calculation results can also support the management of rockfall. [Methods] Based on field investigation and UAV aerial survey, the distribution, material composition and disaster characteristics of perilous rock in the study area were analyzed. RocPro3D software was used to simulate the three-dimensional kinematics of rockfall, evaluating the disaster damage, and calculating the engineering treatment effect of dangerous rock with different particle sizes and protective facilities. [Results] The results show that the combined joints caused by tectonic compression and air unloading cut the dangerous rock, and the weathering cavity at the bottom of the dangerous rock reduces its stability. The hydrostatic thrust of the trailing edge crack and the seepage of the crack are the typical causes of the rockfall. After the collapse of dangerous rock, the velocity and impact energy increase first and then decrease, and the bounce height fluctuates and tends to decrease. The dangerous rock zone in the study area poses a major threat to the management house at the foot of the slope. It is an effective disposal measure to clear the side to the dangerous rock with a diameter of less than 0.8 m, and to adopt a passive protection network with a height of 5.0 m and a protection level of 1000 kJ. The local concentration position of the spatial distribution of the rockfall movement trace should be properly enhanced. [Conclusion] The three-dimensional simulation of kinematics can obtain the information of movement trace, velocity, energy, bounce height and unit density of rockfall, which breaks through the limitation of two-dimensional section calculation in space and is of great significance to disaster damage evaluation and geological disaster prevention.
Identification and genetic mechanism of recharge sources in groundwater-rich area of Changxiao karst water system in Jinan City
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240122
Abstract:
[Objective] In order to identify the recharge sources and reveal the water-rich mechanism in the karst groundwater rich area of Jinan Changxiao Karst water system, [Methods] Hydrochemical method and self-organized neural network (SOM-KM) coupling method were used to reveal the recharge sources and spatial distribution of karst groundwater in the study area, and the contribution ratio of karst groundwater recharge sources in the karst groundwater rich area was quantitatively calculated by using the end-element mixed model. The enrichment mechanism of karst groundwater is explored in combination with topography, geological structure, stratigraphic lithology and catchment conditions. [Results] The results showed that the karst groundwater in the catchment drainage area was similar to the water chemistry of the southern recharge area, the karst groundwater in the lateral runoff area and the Yellow River, and the hydraulic relationship was close, indicating that the karst groundwater in the catchment drainage area was charged by the three sources of the southern mountain area, the karst groundwater in the lateral runoff area and the Yellow River. The contribution ratios of the three components were 75.09%, 21.02% and 3.89%, respectively. [Conclusions] Carbonate rocks are widely distributed and fissure karst develops in the accumulation and discharge area, especially in the Maji - Xiaoli - Guide area. In addition, karst groundwater recharge sources are abundant in this area. In the process of karst groundwater runoff from southeast to northwest, the groundwater is blocked by sandstone mudstone in the north, and the groundwater accumulates in the contact zone between soluble rock and non-soluble rock. Formation block type karst underground water-rich structure. [Research significance] By revealing the enrichment mechanism of karst groundwater in Changxiao Karst water system, it can provide scientific support for accurate calculation of recoverable resources and water supply of Baoquan in Jinan. Key words: Jinan; Changxiao karst water system; Karst groundwater; Supply source identification; Water enrichment mechanism.
Genesis of Garnets within pegmatites in the northwestern margin of the Mufushan granite (central Jiangnan Orogen),and its implication for rare metal mineralization: comparison from mineralized and unmineralized pegmatites
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230563
Abstract:
The Mufushan area,in the central Jiangnan Orogen,South China,has become one of the most significant rare metals resource bases in China. The Duanfengshan pegmatite-type Nb-Ta deposit is the only large-sized deposit in the northwestern margin of the Mufushan granitic batholith. However,its genesis and physicochemical conditions are not well studied,in particular of the newly discovered microcline pegmatite-type Nb-Ta mineralization. This study focuses on garnets in the mineralized and unmineralized microcline pegmatites in the Duanfengshan area. Garnets were observed using cathodoluminescence (CL) and backscattered electron (BSE) imagery. The major and trace elements are determined by EPMA and LA-ICP-MS,which are used to discuss the genesis of garnet and indication for Nb-Ta mineralization of microcline pegmatites. Garnets in mineralized and unmineralized pegmatites in the Duanfengshan area both belong to the solid solution series of almandite-spssartite. Almandite (Sps42.56Alm54.63) dominantly occurs in the mineralized pegmatites,whereas spssartite (Sps58.93Alm37.18) mainly distributes in the unmineralized pegmatites. Garnets both are characterized by enrichment in heavy rare earth elements (HREE),and depletion in light rare earth elements (LREE) with Eu negative anomaly (Eu/Eu*=0-0.09). These mineralogical and geochemical features suggest a magmatic origin for garnets within microcline pegmatites in the Duanfengshan area. The two types of pegmatite would be derived from different magmatic sources in the same period. Both formed in medium-high temperatures and medium-low pressures. The low Mn contents (12.07-19.00 wt.%) of garnet in the mineralized pegmatites is caused by the crystallization of niobium-tantalum minerals. Rare metal mineralization is related to the low degree of liquidus undercooling of pegmatite veins in the outer contact zone. The Y/Gd and Y /Dy ratios of garnets,and the appearance of tourmalines in pegmatites confirm that the pegmatitic magmas are enriched in volatiles,which is beneficial to the enrichment of rare metal elements. However,the undeveloped zoning of unmineralized pegmatites is due to the high degree of liquidus undercooling in the inner contact zone.
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230576
Abstract:
Abstract:The development of karst reservoirs in the Maokou Formation of the Lower Permian in southern Sichuan is a key formation for conventional oil and gas exploration in southern Sichuan. The development level of supergene karst reservoirs is directly controlled by the rich and varied karst microgeomorphology, resulting in strong lateral heterogeneity of karst reservoirs. This article uses 3-D seismic data, combined with strata thickness, gradient structure tensor attributes, and geological body carving techniques, to characterize the microgeomorphic characteristics of Dongwu karst in the Yunjin area. Predicting favorable zones for surface karst reservoirs through model forward modeling and amplitude attributes. Research suggests that:①The Yunjin area had significant differences in karst micro- geomorphology during the Dongwu period, with a series of karst caves developed, which exhibited a seismic feature of "pull-down" of the seismic event event axis at the top boundary of the Maokou Formation;②Effectively characterizing the distribution pattern of karst collapse bodies in Yunjin syncline area using gradient structure tensor attributes combined with geological body carving technology. There are three distribution patterns of karst collapse bodies on the plane: isolated, linear, or contiguous;③The seismic amplitude on both sides of the edge of the karst collapse body is weakened, and the karst process is strong, with the development of karst caves, which is a favorable zone for reservoir development. This research result has guiding significance for the subsequent prediction of Maokou Formation reservoirs.
Prediction of the Wave Characteristics Induced by a Gaint Accumulated Landslide In Lantsang River
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230598
Abstract:
In the upstream of the Lantsang River, there is a plan to construct the RM hydropower station. Its reservoir operation could potentially trigger deformation and instability of the RS giant deposit on the left bank near the dam, leading to landslide wave disasters and posing threats to the safety of dam infrastructure and downstream residents. This study combines extensive geological surveys and physical mechanics experiments to investigate the potential instability and failure modes of the RS deposit under reservoir filling. Based on this, a three-dimensional numerical model of the entire river channel from the RS deposit to the dam section was established. An analysis of the dynamic evolution of landslide-wave chain disasters caused by the RS deposit was conducted, predicting parameters such as the initial wave height, wave height along the opposite bank, propagation characteristics, wave height at the dam front, and height of wave climbing along the dam. The results indicate that as the reservoir water level gradually rises, the RS deposit is most likely to undergo significant instability and large-scale failure above a reservoir level of 2800m. The rear rupture boundary is identified as the gravel layer of the deposit, while the front shear boundary is the fine particle layer in the middle and lower parts of the deposit. The instability and failure of the deposit lead to the triggering of landslide waves, with the peak wave height reaching approximately 31.5m near the water inlet and lasting about 15s. As the wave propagates downstream, there is a decrease in wave height of 39.5% at the No. 1 river bay, reaching the dam in approximately 147s and continuing to climb along the dam slope. The climbing wave height is approximately 2.6m and lasts for 180s, with no risk of overtopping by the initial or subsequent smaller waves. After being impeded by the dam, the initial wave propagates upstream, creating a backflow phenomenon, which, combined with subsequent waves, forms a locally high wave area. At monitoring point P5, the maximum backflow wave height reaches approximately 4.56m and lasts for 219s. During the wave propagation process, the topography of the river bay and backflow phenomena significantly accelerate the energy dissipation of the waves, effectively reducing the risk of wave impact and secondary disaster.
Research on the composition and properties of soil substrates for ecological restoration of rocky slopes
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230445
Abstract:
[Objective]With the rapid development of the economy in China, the exploration of mineral resources, construction of roads, electricity and other infrastructure have produced a massive number of rocky slopes, which have a serious impact on the regional ecosystem. Because of the simple process, economy and high efficiency, the external-soil spray seeding is widely used in the ecological restoration of rocky slopes. However, the poor adhesion and stability of traditional spraying soil substrates lead to unsustainable restoration of rocky slopes. Therefore, there is an urgent need to develop targeted ecological restoration soil substrates. [Methods]In this study, we analyzed the properties of soil substrates with different compositional components, including substrate water retention, horizontal shrinkage, weight capacity, plant germination number, and plant height through pot experiments and orthogonal experiments, and screened the soil substrate with excellent performance. On the basis of the above study, the erosion resistance of the screened soil substrates was analyzed through the erosion resistance test, and the optimal soil substrate suitable for ecological restoration of high steep rocky slopes was further screened. [Results]The results showed that moderate content of water retaining agent increased the germination rate and height of plants, while slightly higher content of binder (greater than 0.15%) not only decreased the height of plants, but also reduced its growth rate. The properties of the soil substrates with different compositions differed significantly, but almost all indicators were better than those of the natural soil in the blank control group. After screening, the soil substrates in groups P6, P10, P16, P1 and P15 showed good plant growth, physical structure and water retention. Substrate loss increased significantly with increasing slope and rainfall intensity, and soil substrates in groups P15 had superior erosion resistance. [Conclusions]Therefore, the soil substrate can be directly applied to the ecological restoration of rocky slopes when the slope gradient is small (up to 60°) or when there are occasional heavy rainfalls. When the slope gradient is large (60° or more) or when there are frequent heavy rainfalls, the soil substrate should be paired with engineering applications such as protective netting.
Identification and saturation calculation of hydrate bearing gas layer in ultra-shallow loose sandstone in deep water
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240082
Abstract:
In the process of marine gas hydrate exploration, the electrical response characteristics of hydrate-bearing gas layers are extremely complex, which leads to great difficulties in the qualitative identification and quantitative evaluation of hydrate-bearing gas layers. Therefore, based on the logging response characteristics of deep-water ultra-shallow loose sandstone hydrate gas reservoirs in the South China Sea, combined with qualitative identification methods such as porosity difference method, neutron-density curve overlapping method, shear modulus method, etc., the saturation of hydrate gas layers was identified and the method of inverting longitudinal wave velocity and resistivity at the same time to find the minimum joint error was used to solve the saturation of hydrate gas layers. The results show that the method of joint inversion of acoustic wave and resistivity logging to calculate the saturation of hydrate gas layer is feasible and reliable, and the hydrate saturation and shallow gas saturation can be calculated at the same time, the calculation results of the joint inversion of Well Z in block L are in agreement with the core saturation of 81.25%, and the joint inversion results of Well Y in block L are in agreement with the calculation results of hydrate or shallow gas calculation model alone by nearly 85%, which can provide a reference for the identification of hydrate gas layers and the calculation of saturation in the field.
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230484
Abstract:
International Research Progress and Development Suggestions of Hot Dry Rock EGS System Flow Test
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230644
Abstract:
Hot dry rock is a widely distributed and abundant geothermal resource. Its development and utilization are of great significance for reducing fossil energy consumption, alleviating environmental pollution and ensuring energy security. The enhanced geothermal system is the main way to develop dry hot rock at present, which is generally implemented through several links such as project site selection, geothermal drilling, thermal storage construction, flow test and commissioning power generation. Among them, the cycle test is an important link to undertake the construction of thermal storage and power generation engineering, which is used to form injection-production well groups, evaluate the cycle circuit, expand the heat exchange capacity, and lay the foundation for the final safe and stable realization of power generation objectives. The implementation process of the flow test is characterized by long-term and complexity, which is easy to cause problems such as insufficient connectivity, strong microseism, liquid leakage, scaling of the circulating fluid, and insufficient equipment reliability. Therefore, the flow test construction of dry-hot rock development sites in the world is often interspersed with drilling and reservoir reconstruction, and accompanied by scheme adjustment, to gradually achieve the goal of power generation. This paper briefly summarizes the flow test experience of developing EGS system for typical dry hot rock at home and abroad, expounds the influence of various factors on flow test, and puts forward development suggestions based on the actual situation of the site in Qinghai Republic, providing reference for technical personnel engaged in relevant fields.
Fine-grained Identification of Internal Characteristic Zones within the Strike-slip Fault Using the XGBoost Algorithm
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230583
Abstract:
Constrained by the strong heterogeneity within the internal structure of the strike-slip fault, the variability of reservoir spaces, and the complex distribution of fluids, the logging responses among the three characteristic zones within the strike-slip fault—namely, the fracture zone, fractured zone, and dissolution zone—are highly complex and variable. This complexity poses challenges for the effective utilization of imaging and conventional logging data to identify these three internal characteristic zones within the strike-slip fault.An analysis of the logging response characteristics of the "three zones" within the internal structure of the strike-slip fault was conducted. Sensitive logging curves were selected to construct a feature vector space based on mean and variance. The Extreme Gradient Boosting (XGBoost) algorithm was employed to establish XGBoost regression prediction models for the dissolution zone, fractured zone, and fracture zone within the strike-slip fault. Key parameters of the XGBoost model were optimized using multi-class evaluation metrics, resulting in an improved accuracy of identifying the "three zones" within the internal structure of the strike-slip fault.Utilizing the constructed XGBoost model, the identification of the "three zones" within the strike-slip fault in the study area achieved an accuracy rate of 88.89%. This indicates that the XGBoost-based identification model for the internal characteristic zones within the strike-slip fault can effectively distinguish the fracture zone, fractured zone, and dissolution zone. It holds valuable implications for a fine-grained characterization of the internal structure of the strike-slip fault.
Automatic Detection of Effective Microseismic Events Based on U-Net Neural Network
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230689
Abstract:
Abstract: [Objective]Automatic pickup of effective events is an important part of microseismic monitoring, and the accuracy of pickup directly affects the accuracy and reliability of subsequent seismic source localization and seismic source mechanism inversion. [Methods] In this paper, a 10-layer U-Net neural network model framework is constructed, the original microseismic data from 3D finite-difference simulation and the raw microseismic data from the measured gas storage reservoirs are made into labeled images, which are cut into 128*128 sized slices and input into the U-Net neural network for learning, and then the output of predicted slices is outputted and merged, and then the predicted images are binarized, and the microseismic effective events are extracted in the end of the P-wave first arrivals. This makes the edge segmentation of background noise and effective signal image more fine, and improves the efficiency and accuracy of automatic picking up of effective microseismic events.[Results]Quantitatively analyze and compare the pickup rate, wrong pickup rate and pickup error of U-Net method and STA/LTA method, the test results show that the pickup effect of U-Net is better than that of STA/LTA method, and U-Net also has a strong anti-jamming ability and generalization ability; Evaluate the effect of different label widths on the first-to-pickup results, the results show that the label pickup effect based on the event's primary cycle is The results show that the label pickup effect based on the main cycle of the event is the best.[Conclusion] The U-Net neural network first-to-automatic pickup algorithm established in this paper is an important part of the highly efficient and high-precision reservoir integrity microseismic intelligent monitoring system, which is of great significance to improve the level of microseismic monitoring technology in China.
The most dangerous sliding surface of the three-dimensional slope of the open-pit mine was generated based on multiple profiles
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230690
Abstract:
At present, the two-dimensional profile is widely used for slope stability analysis, which can efficiently and accurately evaluate the stability of the slope. However, the two-dimensional section cannot describe the three-dimensional spatial shape and three-dimensional sliding body of the most dangerous sliding surface of the slope. In order to solve this problem, based on the stability analysis of the two-dimensional section slope, the three-dimensional most dangerous sliding surface of the slope is fitted by using the spline function by associating multiple sections with the three-dimensional slope model. Firstly, the relationship between the two-dimensional profile and the three-dimensional slope space is established by setting the profile name, horizontal coordinate positioning and elevation positioning of the graphic elements in the profile line and the two-dimensional profile. Secondly, the most dangerous sliding surface lines of each section are automatically generated, and the most dangerous sliding surface lines of each two-dimensional section are converted to three-dimensional slope space by using the coordinate transformation formula. Finally, the spline function interpolation is used to fit the most dangerous slip surface lines in the three-dimensional space to construct the three-dimensional most dangerous slip surface. Taking the southwest slope of an open-pit mine in Xilinhot, Inner Mongolia as an example, a three-dimensional engineering geological model of the slope is established, and five two-dimensional profiles for slope stability analysis are generated. Through this method, the three-dimensional most dangerous sliding surface and three-dimensional sliding body of the slope are successfully generated.
Discussion on fine 3D modeling method of complex vein ore body
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240050
Abstract:
Abstract: 【objective】 The surface structure and internal physical properties of geological bodies are simulated by using 3D geological modeling technology, which provides a reliable basis for revealing the spatial distribution of geological resources, resource estimation and resource development, and is the core technology of the construction of "glass earth". It is also an important carrier of geological time and space big data. Since the 1990s, 3D geological modeling technology has been developed rapidly. Researchers proposed many different modeling methods, but there were still many problems in fine modeling of complex orebodies. Compared with the implicit modeling method, the explicit modeling method was more accurate in depicting small-scale geological structure features. However, for the large-scale fine 3D modeling of geological bodies such as complex vein orebodies, there were still some problems, such as low modeling accuracy and poor morphological expression of the model, so it is difficult to meet the needs of mine production and resource estimation at present. 【Methods】 In this paper, aiming at a series of complex geological phenomena of local vein orebody, such as bifurcation compound, non-ore skylight, rock entrapment, fault cutting and so on, the techniques of orebody split line, segmented modeling and orebody suture are comprehensively used to construct orebody split line, segmented modeling, orebody suture and so on. Four kinds of explicit 3D modeling methods of complex vein orebody, such as bifurcation composite orebody, non-ore skylight orebody, stone-bearing orebody and fault cutting orebody are studied systematically. Among them, the constraint point is generally located in the ore center and the outline of the orebody, and the complex part of the model needs to add constraint points to complete the constraint of the shape of the orebody. The splitting line is the connecting line between the cusp-out point at both ends of the boundary line of the orebody and the central point of the ore-seeing project. it is mainly used to split the complex vein orebody, and the split line is used to model the branch-bifurcated composite orebody according to the regional geological law. Segmented modeling is to model the complex parts of complex orebodies separately. The stitching of orebody is to assemble the segmented model along the strike to form a complete model. 【Results and conclusion】 Through the above technology and the explicit modeling method based on measured data, the high-precision and fast 3D modeling of complex vein orebody is realized, and the difficult problem of narrow, thin and complex vein orebody modeling is solved effectively. The 3D modeling process of different complex vein orebodies is improved, and the orebody model is displayed in 3D space in multi-angle, and the most real geological shape of the orebody is reconstructed with the outline of the orebody. High-precision model will not only obtain detailed 3D information of orebody, but also will grasp the distribution law of orebody quickly and accurately. This modeling method is of great significance to the fine 3D modeling of rare and precious metal and other complex vein orebodies, the estimation of mineral resources and the formulation of mineral resources development and utilization plan, and will better guide the exploration and prospecting work.
Tracing of the sources of dissolved organic matter in coastal groundwater based on fluorescent indices and end-element mixing analysis
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230711
Abstract:
Dissolved organic matter (DOM) in coastal groundwater is derived from multiple sources including marine water, river and leachate from sediments. Quantitative estimation of the contribution of difference sources to coastal groundwater is importing for understanding the carbon reactive transport in the coastal area. Isotopic tracer, fluorescent indices, and end-element mixing analysis (EMMA) were used to identify the sources of DOM in coastal groundwater and quantify their contributions. The results showed that DOM in coastal groundwater was mainly originated from DOM in river water, seawater and sediments, with contributions of 44.0% ± 22.2%、33.0% ± 10.8% and 22.9% ± 13.1%, respectively. Groundwater collected from the north part of study is affected by both seawater intrusion and fresh water recharge, showing a high proportion of seawater DOM and autogenous characteristics. In the south part, groundwater has higher total dissolved solids (TDS), saline water releases DOM in sediments, showing higher proportion of DOM in sediments and humification characteristics. This study demonstrates the DOM in coastal groundwater is affected by hydrodynamic and hydrogeological conditions. End-element mixing analysis based on fluorescent indices can efficiently quantify the sources of DOM in coastal groundwater, which provides a new perspective and assessment method for the study of terrestrial-oceanic carbon cycle.
Study on the influence of aggregation angle of aggregated landslide debris flows based on discrete element model
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230564
Abstract:
Abstract: [Objective]Landslide debris flow is a common geological disaster, which has the characteristics of large scale, long sliding distance and fast speed, and the terrain of hillside ravines and valleys will affect the trajectory of landslide debris flow and then block, turn, pile up and a series of impacts, so the landslide debris flow is not only a simple straight line path, but also by the influence of the terrain factors, the path of its movement is complex and varied.[Methods]This paper is mainly based on the aggregation behavior in different motion trajectories of landslide debris flows, and uses EDEM software to analyze the motion impact and accumulation characteristics of symmetric aggregated landslide debris flows in different aggregation angles.[Results]The results of the study show that: (1) the effect of the polymerization angle on the movement velocity: the larger the polymerization angle, the smaller the Vy, the higher the degree of separation of the landslide debris flow, and the longer the landslide sliding time; (2) the effect of the polymerization angle on the accumulation morphology: the larger the polymerization angle, the landslide is stabilized at the foot of the slope, and the morphology of the accumulation zone, the length of which is increased on the slide side, and the height of which is decreased at the blocking structure; (3) the effect of the polymerization angle (3) Effect on impact performance: the larger the polymerization angle, the lower and later the peak impact force on the barrier structure; the residual impact force after stopping the movement to form a static accumulation area is also lower, and the value of the residual impact force is also closer to the peak impact force.[Conclusion]The research results provide a fundamental role for the in-depth study of the complex path movement of landslide debris flows and a theoretical reference for the optimization of landslide debris flow control structures.
Quantitative characterization of clastic particle size of tight sandstone and its indicative significance for productivity
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230582
Abstract:
[Objective]Particle size analysis is important for the evaluation of clastic oil and gas reservoirs because it can identify the stratigraphic depositional environment and evaluate the permeability of reservoirs. [Methods]Taking the dense sandstone reservoir of Shaximiao Formation in Tianfu Gas Field in Sichuan Basin as the research object, firstly, we analyzed the influence of the particle size and shape of the clastic rock on the permeability of the reservoir, and then, based on this, we combined the median value of the particle size, the C value of the particle size, and the sorting coefficient, and put forward a comprehensive characterization of the indicator parameter of the particle size PI, and then we carried out a principal component analysis on the natural gamma, the photoelectric absorption cross section index, and the neutron, which are more sensitive to the particle size. The exponential relationship model between the particle size indicator parameter PI and the principal component parameter is established. Finally, the correlation between the particle size indicator parameter PI and reservoir production capacity is analyzed by combining the test and logging data. [Results]The statistics of 8 test gas sections of 7 wells in Shaximiao Formation of Tianfu Gas Field were collected, and the values of particle size indicator parameter PI of 7 wells were calculated by the above method, and the response relationship between the unimpeded flow rate of the test sections and the particle size indicator parameter PI was analyzed, and the results show that: the cumulative values of unimpeded flow rate of the test sections in Shaximiao Formation of Tianfu Gas Field and the particle size indicator parameter PI, X, showed an exponential relationship, and their correlation coefficients reach to 0.85. [Conclusion]The study shows that for reservoirs with lithology mainly dominated by medium-fine-grained sandstone, with large variation of grain size, and with storage space dominated by residual intergranular pores, the grain size indication parameter PI can to some extent indicate the production capacity of this type of reservoir.
Structural features of south Hubei Province along the northern margin of the Mufushan pluton and structural ore-controlling of polymetallic deposits
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230525
Abstract:
[Objective] An intensive Early Cretaceous magmatic-hydrothermal metallogenic system occurred in the Mufushan area, central Jingnan Orogen. The Jingnan Orogen in the South China Block resulted from the accretion and subsequent collision of the Yangtze and Cathaysia blocks during the Early Neoproterozoic, consisting of Li-Be-Cs-Nb-Ta rare metal deposits and Pb-Zn-Cu-Au-Sb nonferrous metal deposits. The northeast Hunan Province and the south Hubei Province are located to the
Geochemistry, zircon U-Pb age and Lu-Hf isotope characteristics of in Daliuhang Mesozoic granites in Jiaodong area and their tectonic significance
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230693
Abstract:
[Objective] To determine the Mesozoic granite type, age and tectonic setting and discuss the relationship between the granite and gold mineralization in Daliuhang, Jiaodong Peninsula. [Methods] In this study, the Mesozoic Yanshanian Linglong-type granites (Qijiagou monzonitic granite) and Gujialing-type granites (Gusidian monzonitic granite), which were located in the north of Qixia-Penglai gold metallogenic belt in eastern Jiaodong Peninsula. These samples are selected to analyze whole-rock geochemistry, U-Pb dating and Lu-Hf isotope study of zircon. [Results] The results show that the U-Pb age of the zircon from Qijiagou monzonite is 172.8±1.5 Ma, and the εHf(t) value of the zircon is -27.7 ~ -20.3. The zircon U-Pb age of Gusidian monzonitic granite is 127.3±0.8 Ma, the εHf(t) value of zircon is -15.7 ~ -13.4. The 87Sr/86Sr ratio of Gusidian monzonitic granite is 0.710937 ~ 0.712735, and the εNd (t) range is -16.8 ~ -11.3. [Conclusion] The source of Qijiagou monzonitic granite is ancient lower crust, which is mainly from the North China Craton lower crust. The magma source of Qijiagou monzonitic granite may be mixed with the Yangtze craton crust. Gusidian monzonitic granite is formed by partial melting of mafic rocks of lower crust, which added mantle components in the process. The diagenetic tectonic background of Gusidian magma formation is extensional, which may be caused by the subduction and retreatment of the Pacific plate. The Gusidian monzonitic granites have high coordination with the characteristics of early Cretaceous gold mineralization in Jiaodong Peninsula, suggesting that Gusidian monzonitic granite may be related to gold mineralization in this area.
Source-sink characteristics of Weihe Graben and its controlling effect on deposition and reservoir characteristics
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230531
Abstract:
Property of provenance plays an important role in controlling Paleogene deposition and reservoir development in China's offshore basins. However, due to the cost of coring and the interpretation ambiguity of seismic data, the relevant understanding lacks visual evidence support. Weihe Graben is a Cenozoic rifting basin. Regional geological studies reveal that there are significant differences in provenance system between north and south of Weihe Graben, and its tectonic setting and provenance system show strong analogy with the offshore basins. Based on outcrops and systematic sampling in Weihe Graben, zircon U-Pb dating, cast thin section, backscattering and X-ray diffraction analysis are carried out to analyze the source system, deposition and reservoir characteristics of the northern and southern sandbodies in Weihe graben. The detrital zircons in the northern Huacheng section have two typical peaks of ~2500 Ma and ~1800 Ma reflecting the influence of North China Craton, and two younger peaks correspond to Caledonian and Hercynian movement. The conglomerate gravel types at the bottom of the sequence are mainly carbonate rocks, calcarenous clastic rocks and metamorphic rocks, which have distinct characteristics of Paleozoic carbonate rocks and clastic rock of Weibei Uplift in the north. The late Caledonian and Late Indosinian peaks dominate the detrital zircons in the southern profiles, and the gravel types are dominated by granites and metamorphic rocks, with distinct provenance characteristics of the southern Qinling Mountains. Typical profile observations show that the difference in provenance leads to significant differences between sedimentary system and reservoir characteristics. The carbonate provenance area of Weibei Uplift corresponds to a small and mud-rich sedimentary body, and the bottom conglomerate directly changes to silty sand and mudstone, with high calcium content in the reservoir. The southern Qinling orogenic belt is characterized by large distribution of sedimentary bodies, multi-cycle sand-rich deposits, and low calcium content. Different types of provenance systems provide material basis and prerequisite for reservoir and subsequent diagenesis. The outcrop system analysis of Weihe graben can provide references for offshore basin research in China.
Experimental study of dissolution damage to carbonate rocks by acidic leachate
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230633
Abstract:
Strongly acidic wastewater is highly corrosive to carbonate rocks, which can lead to significant changes in the physical and mechanical properties of carbonate rocks. In this paper, through carrying out different flow conditions, different time length of phosphogypsum acidic leaching solution on the dissolution of limestone test research, analyze before and after the test of limestone specimens of the apparent characteristics, quality, porosity, uniaxial compressive strength, and acoustic emission counts and other indicators of the law of change, to discuss the dissolution damage of acidic leaching solution to carbonate rock and mechanical damage, revealing the impact of the acidic leaching solution on the physical and mechanical properties of the carbonate rock. The test results show that the dissolution rate and porosity increment of the rock samples are positively correlated with the dissolution time and the flow rate of filtration solution, and the mechanical strength is negatively correlated with the dissolution time and the flow rate of filtration solution. With the dissolution, the surface of the rock samples will be attached with thicker and thicker fluorite minerals, which makes the dissolution rate of the rock samples slower. The damage form of the uniaxial specimen gradually changed from shear damage to tensile damage. Under the acidic environment of phosphogypsum leachate dissolution, the internal mineral composition of limestone is dissolved, which causes changes in macro-mechanical parameters, and the results of the study can provide theoretical and experimental data for the stability analysis of karst media under the influence of acidic wastewater, acidic wastewater treatment, and tailing project safety design.
Orbital cycle recognition and sequence stratigraphic division of the Lower Carboniferous Dawuba Formation shales in Southwest Guizhou
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230546
Abstract:
【Objective】The Lower Carboniferous Dawuba Formation in southwest Guizhou has developed a set of shale with great exploration potential. However, the scheme of sequence stratigraphic division is not unitive and the understanding of sequence development mechanism is unclear, which restricts the promotion of unconventional oil and gas exploration. Therefore, this paper carries out cyclostratigraphic analysis and sequence stratigraphy research on this set of shale stratum, aiming to realize the "quantitative" stratigraphic division of shale from the perspective of orbital cycles.【Methods】The Well QSD-1 (1457-2466 m) was selected as the research object, and the gamma ray logging curve was used as the proxy index, the cyclostratigraphic analysis and sequence stratigraphy were carried out by using time series analysis, INPEFA analysis and wavelet analysis.【Results】Obvious orbital cycles have been recognized of the Lower Carboniferous Dawuba Formation shales in Southwest Guizhou. The optimal sedimentation rate of the stratum was estimated by COCO is 16.4 cm/ka, and the matching sedimentation thickness of 66.42 m represents the long eccentricity cycle of 405 ka. Spectral analysis was conducted again for GR series (1457-1932 m and 1932-2466 m) of Well QSD-1, and the optimal sedimentation rate was estimated to be 16.5 cm/ka in the upper section and 11.2 cm/ka in the lower section. The filtering results show that 19 long eccentricity cycles are recorded in Dawuba Formation. The "floating" astronomical time scale of Dawuba Formation is established, and the duration of Dawuba Formation is estimated to be about 7.86Ma. The relative sea level change curve of Dawuba Formation is restored by establishing the sedimentary noise model (DYNOT and ρ1) of the research interval. Based on the age framework established by the cyclostratigraphic research, according to the extreme value of the relative sea level change curve, combined with the results of INPEFA analysis and wavelet analysis, the third-level sequence boundary and the maximum flooding surface of Well QSD-1 were recognized. Six third-order sequence boundaries and five third-order sequences were recognized in Well QSD-1 Dawuba Formation, and the development of third-order sequences were correlated by obliquity amplitude modulation (AM) cycle (~1.2 Ma). 【Conclusion】The research method of cyclostratigraphy is applied to the stratigraphic division of Lower Carboniferous Dawuba Formation shale in southwest Guizhou, and the relationship between astronomical orbit parameters and relative sea level changes at different time scales is discussed, and the third and fourth order stratigraphy are divided. Cyclostratigraphic provides the possibility for the correlation of marine shales on the ten thousand years time scale, provides a fine age framework for the prediction of high-quality source rock development intervals in shale oil and gas exploration, and provides theoretical guidance for oil and gas exploration in shale.
Research on information extraction method of dangerous rock mass on high and steep slopes based on multi-source remote sensing data fusion
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230695
Abstract:
Abstract:[Objective]There are a large number of high and steep slopes in mountainous areas in my country. Due to their hidden and dangerous characteristics, it is currently difficult to accurately obtain the distribution location and characteristic information of rock masses on high and steep slopes through manual surveys and single non-contact measurements. [Methods]This paper fuses point cloud data obtained from airborne LiDAR, ground LiDAR and UAV oblique photogrammetry with multi-source data to complement each other's advantages. The fused point cloud is then used to analyze high and steep slope hazards. Extract information from the scale boundary, trailing edge characteristics, occurrence information and structural plane characteristic parameters of the rock. [Results]The results show that the multi-source data fusion method used in this article effectively complements the advantages of various data. The fused point cloud is used to extract scale boundary, trailing edge information and structural plane characteristic parameter information of dangerous rocks on high and steep slopes. The extraction accuracy meets [Conclusion]The relevant specification requirements provide a technical method for the refined extraction of geometric parameter information of rock mass on high and steep slopes in mountainous areas.
Numerical study on the disturbance law between rock fractures in the coupling process of high voltage electric pulse- hydraulic fracturing
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230364
Abstract:
The purpose of this study is to investigate the disturbance law between rock fractures during the coupling process of high-voltage electric pulse-hydraulic fracturing. Based on elasticity, fracture mechanics, damage mechanics, the discharge process of high-voltage pulse discharge under water pressure (3 MPa) was numerically simulated by using extended finite element method, and the cracks in rock mass were analyzed. The results show that under a discharge voltage of 5 kV, the maximum crack width of high-voltage electric pulse-hydraulic fracturing is increased by 35% compared to traditional hydraulic fracturing. With the increase of discharge voltage, the maximum crack width and crack initiation pressure of cracks increase, which improves the interference ability between cracks. In addition, the interference between cracks in rock mass is also related to the principal stress difference, injection rate and the number of cracks. Specifically, under the same voltage, the faster the injection rate, the longer the crack length, the more obvious the stress shadow effect, and the stronger the disturbance between cracks; Under the same injection rate, the larger the principal stress difference, the more obvious the directionality of the crack extending towards the maximum principal stress. The initiation pressure and maximum crack width both decrease with the increase of the principal stress difference. Multiple crack branches can expand and cross each other at the same time, and the stress shadow area of three cracks is wider than that of two cracks. The research results aim to provide a theoretical basis and research method for the research of underwater high-voltage electric pulse fracturing and coal seam permeability enhancement technology, and lay a certain foundation for artificial control of cracks in practical projects.
Characteristics and causes of difference of physical properties of deep and ultra deep tight sandstone reservoirs: a case study of the Bashijiqike Formation in Bozi area of Kuqa Depression
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230567
Abstract:
Abstract: [Objective]Despite depths exceeding 8000 meters, it still retains high-quality reservoir and exhibits prolific production of industrial gas flow in Bozi area of Kuqa Depression. However, there are obvious differences in the physical properties plane of the tight sandstone reservoirs of the Bashijiqike Formation. In order to clarify the development characteristics of such reservoirs and reduce the risks associated with deep-ultra-deep oil and gas exploration. [Methods]Based on the experimental analyses of well logging, thin section petrography, high pressure mercury injection and PVT phase diagrams, the characteristics of tight sandstone reservoirs and the causes of physical property differences were discussed. [Results] The rock types of Bashijiqike Formation reservoir in Bozi area which the study highlights are medium-fine grained lithic feldspar sandstone and feldspar lithic sandstone. Notable differences exist in the spatial distribution of carbonate cement content. Original porosity in the medium-fine sandstone reservoirs that ranges from 32.4% to 38.1%, exhibiting comparable intergranular compaction strength primarily reliant on point-line contacts. Southern reservoirs maintain an average porosity of 8.6% and an average permeability of 3.4 mD. Central reservoirs present an average porosity of 6.53% and an average permeability of 0.65mD. The average porosity and permeability of the northern reservoir are 4.9% and 0.62mD respectively. Primary intergranular pores dominate the southern reservoir space, whereas residual intergranular pores and dissolution porosity prevail in the northern and central zones. Furthermore, superior pore-throat structures characterize the southern region compared to the northern and central sectors. [Conclusion] The physical properties of sandstone reservoirs in Bozi area are controlled by sedimentation, diagenesis and tectonic processes (fissures), among which carbonate cementation emerging as the principal factor of the late reservoir physical properties alterations. Overpressure, hydrocarbon fluid charging, and fracture development significantly affect carbonate cementation, subsequently causing variations in reservoir physical properties. Stronger overpressure, earlier oil and gas charging time and limited fracture filling result in better reservoir properties in southern Bozi than those in northern and central areas.
Sedimentary Characteristics and Evolution Law of Shallow-Water Fan Delta: A case study of Baikouquan Formation in Madong slope area, Junggar Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230518
Abstract:
[Objective]Conglomerate is unique oil and gas reservoir, and understanding its sedimentary origin and evolution is important for accurately predicting the distribution of high-quality reservoir. [Methods]Based on core logging, petrology identification, heavy mineral and grain size analysis, combined with well logging data, the sedimentary characteristics, spatial distribution and sedimentary provenance of the Lower Triassic Baikouquan Formation conglomerate in the Madong slope area are defined, the sedimentary mechanism of the formation is clarified and the sedimentary model is established. [Results]The results show that the Baikouquan Formation was deposited in the shallow-water fan delta, and the fan body developed three subfacies, namely fan delta plain, fan delta front and pro-fan delta, including 9 microfacies, containing debris flow, braided channel, flood deposit, subaqueous debris flow, subaqueous main channel, subaqueous branch channel, sandy clastic flow, far sand bar and pro-fan delta mudstone deposits. It contains 10 types of lithofacies. [Conclusion]Combined with the paleoclimate background of the early Triassic which changed from drought to moisture, the conglomerate is the sedimentary product of flood induced gravity flow, which has the characteristics of complex lithofacies associations, significant signs of eventful deposition, sedimentary model dominated by paleoclimate, and obvious transformation of lake wave. In terms of spatial extent, the grain size of the Baikouquan Formation conglomerate in the Madong slope region gradually becomes finer from bottom to top, which reflects the sedimentary sequence of the lake transgression and presents the signature of a multi-period superposition of debris flows, underwater debris flows, and subaqueous channel deposits.
Reservoir characteristics and development control factors of Benxi Formation bauxite in Linxing area of Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230657
Abstract:
In recent years, the bauxite gas exploration of Taiyuan Formation in Longdong area of Ordos Basin has made a major breakthrough, which has attracted wide attention at home and abroad. In the same period, the bauxite rock gas of Benxi Formation in Linxing area has also made some progress, but the characteristics and controlling factors of bauxite reservoir in this area are unclear, which restrict the exploration process. [Objective]In order to identify the reservoir characteristics and control factors of Benxi Formation bauxite in Linxing area, [Methods]The paper carried out XRD, casting sheet image, SEM-EDS, mercury intrusion porosimetry, nitrogen adsorption, carbon dioxide adsorption, routine porosity detection and other analysis methods. The mineral composition, pore structure and physical properties of the bauxite reservoir are characterized, and the controlling factors of the development of the bauxite reservoir are discussed based on seismic logging data. [Conclusion]The results show that the aluminum-bearing minerals in the bauxite of Benxi Formation in Linxing area are mainly diaspore, and the pore types are mainly intra granular pores, intergranular pores, matrix pores, intergranular pores and micro-cracks, and occasionally organic pores. In addition, the pore volume of bauxite rocks is mainly provided by mesoporous and macroporous pores, and the distribution range of pore peaks is mainly 30-70 nm, 80-130 nm and 4-13 μm. Thirdly, the physical property conditions of the bauxite reservoir are general, with an average porosity of 3.28% and an average permeability of 1.398×10-3 μm2, but the upper section with higher content of diaspore at the bottom still has better physical property conditions. Finally, the development of bauxite reservoir in Linxing area is controlled by palaeo-geomorphology, palaeo-sedimentary environment and diagenesis. Among them, The accumulation and distribution of bauxite are controlled by the paleogeomorphology of depressions and troughs and the enclosed and semi-enclosed intermittent swamps and lagoons sedimentary environment, while diagenesis controls the reservoir space type and physical property conditions of bauxite reservoirs based on the sedimentary environment.
Genetic mechanism of low resistance in shale analyzed by triaxial compression test
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230533
Abstract:
【Objective】The gas shale of Wufeng-Longmaxi Formation in the southern Sichuan Basin shows the low-resistance anomaly in multiple areas. Statistical analysis reveals that the low-resistivity zone (<10 Ω·m) in the Wufeng-Longmaxi shale is spatially associated with tectonic faults. To reveal the coupling mechanism between shale resistivity and tectonic fault, 【Methods】this paper determined the petrological and geochemical characteristics of the outcrop samples obtained from the Wufenglongmaxi shale of Southern Sichuan Basin through analyses of thin-section identification, X-ray diffraction, laser Raman spectroscopy, whole-rock asphalt reflectance, and conventional physical property. Subsequently, the characteristics of shale resistivity change during the deformation were revealed using the triaxial compression tests. The impact of the fracture system generation and the conductive fluid intrusion on low-resistance shale was also clarified.【Results】The results show that the resistivity of shale samples, primarily composed of uniform clay minerals, pyrite, and organic matter with high thermal maturity, significantly decreased after being saturated with various salinity brines. There is a positive correlation between the reduction of resistivity (95.07%-98.70%) and the brine salinity. After reaching the limit of compressive strength, the resistivity of brine-saturated samples generally experienced a further resistivity decrease of 5.7 Ω·m to 25.7 Ω·m (with an average value of 13.3 Ω·m). This decrease maintained a linearly positive correlation with the resistivity observed after cracking.【Conclusion】The intrusion of conductive fluid and the generation of the fracture system in shale were the primary controlling factors for shale resistivity reduction, and the resistivity after cracking was governed by both the intruded brine salinity and the fracture density. This research elucidates and supplements the influence mechanism of tectonic fault zones on shale resistivity, enriching the theoretical framework for understanding the genesis of low-resistivity shale, and holds significant implications for exploration and development of low-resistivity shale formations.
Landslide Disaster Vulnerability Mapping Study in Henan Province: Comparison of Different Machine Learning Models
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230338
Abstract:

Henan Province has a complex geomorphological type and faces the challenge of frequent landslide disasters. Therefore, efficient and accurate landslide susceptibility mapping (LSM) has great significance to local governments and residents. [Objective] However, in the study of LSM, how to choose the suitable machine learning model for Henan landslide disaster data set to improve the evaluation accuracy still needs further investigation. [Methods] The research focuses on Henan Province, where landslide data is collected and compiled into a landslide disaster database. Using the recursive feature elimination method, 11 factors with the highest relative impact on landslides (slope, elevation, plan curvature, profile curvature, land cover, lithology, soil type, precipitation, road density, river density, fault density) are selected and integrated into a spatial dataset. Then, the models of multilayer perceptron (MLP) neural network , random forest, extreme gradient boosting, and support vector machine were trained, and the performances of the models were evaluated using the receiver operating characteristic curve and the area under the curve (AUC). In the end, we create high precision landslide susceptibility zoning map. [Results] The research results indicate that the MLP model has the strongest adaptability to the landslide disaster dataset in Henan Province, achieving the highest AUC of 0.95. In comparison to SVM, XGBoost, and RF models, the MLP model predicts the smallest proportion of landslide disasters in highly susceptible areas, thus more accurately defining high-risk regions for potential landslide disasters. The predicted extremely high and high susceptibility areas are mainly distributed in the western mountainous and hilly areas of Henan Province, where terrain factors play a dominant role in the development of landslide disasters. [Conclusion] The results can provide a reference for the evaluation of landslide susceptibility with high accuracy in large-scale regions.

Experimental study of the freeze-thaw resistance of MICP-treated soil
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230462
Abstract:
[Objective] Microbially induced carbonate precipitation (MICP) method is a potentially effective and environmentally friendly technique to improve the unfavorable soil conditions. MICP treatment can improve soil strength. However, the durability of MICP-treated soil under freeze-thaw cycles has not been investigated. [Methods] This study investigates the effects of freeze-thaw cycles on unconfined compressive strength, erosion resistance, and water retention capacity of soil which treated with MICP under different conditions. The surface of the specimens was treated using the spray method, and then some specimens were subjected to erosion tests. Unconfined compressive strength (UCS) and water evaporation rate of the specimens under different freeze-thaw cycles were tested. Combining the mechanism of soil resistance to erosion damage and the test results of specimens under freeze-thaw cycles, the reasons for the deterioration of reinforced soil properties due to freeze-thaw cycles are investigated. [Results] The results show that the UCS of the sample has increased from 43.83kPa to 69.92kPa after MICP-treated. After 20 freeze-thaw cycles, the UCS of the MICP-treated sample is 1.48 times that of the uncured sample, and the erosion amount of the MICP-treated sample is much less than half of that of the uncured sample. The results indicate that the microbially induced calcium carbonate deposits can effectively fill the internal pores of the soil and bind the loose soil particles, thus significantly improving the soil strength and effectively weakening the damaging effect of freeze-thaw on the soil. [Conclusion] Although the consolidation effect of the soil gradually deteriorated due to the increase of the freeze-thaw cycle, the MICP-treated soil still had high strength under the short-term freeze-thaw environment and could effectively resist the erosion effect of rainwater.
Study on the spatial characteristics and genetic mechanism of geothermal resources in Zhangye Basin by multi-source fusion modeling and heat-flow coupling simulation
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230590
Abstract:
Abstract: The traditional temperature and pressure field analysis approach, which is based on the interpolation of existing borehole data, cannot accurately represent the seepage-heat transfer coupling process of geothermal resources, resulting in insufficient understanding of the genetic mechanism of geothermal resources. First, a high-precision three-dimensional geological model of Zhangye Basin is built by combining multi-source data including borehole information, geophysical information and elevation data. Compared with the traditional interpolation model, multi-source data fusion modeling can improve the accuracy of inter-hole strata by 50-300 m. The numerical simulation of basin seepage-heat transfer field coupling process is carried out. The results show that the multi-field coupling analysis more reasonable represents the temperature and pressure characteristics of the reservoir than the key point spatial interpolation approach. The geothermal water in the study area flows from southeast to northwest and supplies the reservoir via faults. The geothermal field totally heats it during the seepage process. The temperature field is high in the basin center and low around it, with the central temperature reaching 78℃. The water head is greater towards the southeast of the basin's center and progressively drops to the northeast. Finally, a 3D geothermal conceptual model is developed to explain the genetic mechanism of geothermal resources in terms of structural, hydrogeological, and geothermal geological perspectives. This 3D conceptual mode coupling with heat-flow transfer modeling more specifically explain the spatial distribution and reveal more clearly the underlying mechanism of forming the geothermal resources compared with conventional 2D model.
Research on intelligent identification method of shale lithology based on deep coupling of logging curves
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230361
Abstract:
【Objective】The Wufeng-Longmaxi formations in the Yuxi Block of the Sichuan Basin are typical shale gas reservoirs in China. The strong interbedded heterogeneity of these formations leads to a significant amount of redundancy in the collected logging curve information and complex coupling relationships between curves, resulting in the difficulty and low accuracy of lithofacies identification using traditional methods, which urgently needs technical innovation. 【Methods】In this study, based on lithofacies classification and analysis, an intelligent lithofacies identification method combining Principal Component Analysis (PCA) and Random Forest algorithm was developed. 【Results】The research findings are as follows: Firstly, by optimizing the logging curves using PCA, the deep coupling of logging curves can be achieved, thereby reducing the impact of factors such as redundancy of logging information and complex coupling relationships between curves on lithofacies identification, resulting in more scientifically effective data information. Secondly, by adding minor variations to the original data without altering its lithofacies, data augmentation can be achieved, addressing to some extent the problem of poor generalization ability and stability of the model caused by small or imbalanced datasets when using the Random Forest algorithm. Finally, the intelligent lithofacies identification method constructed by combining PCA and Random Forest algorithm achieved an identification accuracy of over 83%, demonstrating its high precision and strong applicability. 【Conclusion】This method not only overcomes the difficulties in lithofacies identification in the study area to a certain extent but also greatly improves the efficiency of lithofacies identification, which is of great significance for promoting the economic and efficient development of shale gas in the study area.
Ore-bearing discrimination of granite rock mass in Nanling area based on data-driven
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230363
Abstract:
As an important participant in mineralization, the study of granite is helpful to understand the geochemical process of tungsten-tin mineralization and distinguish the ore-bearing property of rock mass. In this paper, the data of major elements and rare earth elements of tungsten-bearing granite, tungsten-tin-bearing granite and non-ore-bearing granite in Nanling area are collected, a total of 466 sets of data of 42 rock masses. The geochemical characteristics of the three types of rock masses are summarized and compared.The relationship between ore-bearing properties and geochemical characteristics of rock mass is explored from the perspective of data-driven and machine learning. The restricted Boltzmann machine is used to train the auto-encoder neural network to eliminate the dimensional difference between major elements and rare earth elements, and the intermediate features are extracted. Then the intermediate features are input into random forest and multi-layer BP neural network to establish AE-RF and AE-BP rock mass ore-bearing classification models. The importance of classification characteristics is output by random forest. The results show that the evolution degree of tungsten-bearing granite is slightly higher, followed by tungsten-tin-bearing granite, and the ore-free granite is the lowest.Both models have high accuracy ( > 90 % ) on the test set, and the practical application effect of the AE-BP model on the blind test set is better. Six groups of rock masses were randomly selected as the blind test set. Among the 21 rock masses, the correct rate of 13 rock masses was greater than 80 %, the correct rate of two rock masses was greater than 70 % less than 80 %, and the correct rate of two rock masses was greater than 50 % less than 70 %. There are four rock mass accuracy is less than 50 %. Major elements such as iron, manganese, phosphorus, calcium and magnesium and light and heavy rare earth elements are important features to distinguish the three types of rock masses. The similarity of geochemical characteristics and the difference of tungsten-tin deposit types will lead to the wrong classification of the model, and it is pointed out that the Beitou rock mass has certain metallogenic potential. The main elements such as iron, manganese, phosphorus, calcium and magnesium determine whether the rock mass can contain ore, while light rare earth is an important index to distinguish tungsten-bearing rock mass and tungsten-tin-bearing rock mass. It is believed that the degree of differentiation and evolution of magma determines whether the rock mass can contain ore, and the addition of mantle-derived materials is to distinguish whether the rock mass contains tungsten or tungsten-tin.
An improved method in oil and gas resource assessment—acquiring the coefficient of resource scale variation (k) and its application case
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230371
Abstract:
Reservoir size sequential analysis is based on Pareto principle. The key and the difficulty is acquiring the value of coefficient as ‘k’ which describes the gradient in variation of resource scale, which restricts the effectiveness of corresponding method. Through calculating ratio of the scales of the discovered resources and applying the possible sequential number, a specific optimized methodology is proposed. It mainly includes establishing the cross plot with the axes of sequential number and k according to the calculated ratio, searching and locating the combination of data points from different ratio which can form an approximately straight and vertical line against the k axis, and acquiring the value in the k axis for the intersection as a solution of k. The principles in optimizing and determining the result after acquiring the solution set to satisfy the need in resource assessment are furtherly suggested. From the re-analysis about the classic data set from open published academic literature, it presents that applying related method can effectively acquire the value of such coefficient (k). An actual application about tight gas contained in reservoir as 6th group of Jurrasic Shaximiao formation in Yanting block of Jinqiu gas-producing area located in the center part of Sichuan Basin is also provided as further support. The linear relevant fitting result is favorable between forecast outcome and actual data. The calculated result of resource scale of this case is consistent with current recognition from tight gas exploration in Sichuan Basin. This methodology is with serval advancements, which includes low dependency on geological experience, no demand in setting analytic step size or complicated determinant and matrix manipulation. The subjectivity and calculative complexity in deciding the key parameters are effectively reduced. Corresponding algorithm is achieved to be coded as computer program. The efficiency is accordingly promoted. It can be helpful in further application of reservoir size sequential method.
A Study on the Threshold Model of Landslide Rainfall in Chongqing Based on Different Geological Environment Zones
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230375
Abstract:
Considering the rainfall characteristics and geological environment of historical landslides in the region, it is important to construct a reasonable rainfall threshold model for the prediction and prediction of regional landslide disasters. In this paper, 1368 rain-induced landslides in Chongqing from 2013 to 2021 were selected as the research objects. Based on detailed landslide cataloging data and regional geological environment data, rainfall events were divided and landslide sample database was constructed. Based on Random forest (RF) algorithm, a rainfall threshold model of the day's triggered rainfall - previous effective rainfall (Rd-Rp) was established, and different warning levels were divided based on probability classification. Based on the medium early warning probability, 19 threshold criterions of critical rainfall were constructed according to four geological environments, namely disaster pregnant environment, engineering rock group, land use and soil type. The results show that the Rd Rp threshold model can well reflect the impact of the daily excitation rainfall and the early effective rainfall on the landslide development, and the early effective rainfall plays a leading role in the landslide induction. Different geological environment types have different sensitivity to rainfall factors, and tectonics, engineering properties of rock and soil mass, vegetation coverage and soil properties have important effects on landslide development. The threshold of rock formations mainly composed of hard rocks is higher than that of rock formations mainly composed of soft rocks, and the threshold of forest land is higher than that of cultivated land. The threshold of areas severely damaged by human engineering activities will decrease. The study can provide new ideas and reference for the meteorological early warning management of rainfall landslides in Chongqing.
Exploring the feasibility and influencing factors of phosphorus recovery as struvite from phosphorus-rich groundwater
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230379
Abstract:
ABSTRACT: Phosphorus (P) supply shortage and aquatic P contamination are both emerging as serious crises around the world. Struvite precipitation is the most cost-effective method of P recovery and has been applied to a wide range of sewage resources. However, P recovery as struvite from P-rich groundwater has not been explored properly yet. This study explored the feasibility and influencing factors of P recovery as struvite from groundwater rich in P, Ca, Fe, and fulvic acid (FA). Synthetic and natural groundwater were analyzed by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results showed that a high concentration of Ca can significantly inhibit the formation of struvite. Effects of Fe and FA on struvite formation were relatively weak than Ca. The coupling of factors further exacerbated the inhibition of struvite formation. Notably, struvite precipitation obtained after the coupling of three factors was the most similar to the precipitation obtained from actual groundwater. This indicated that the coupling of three factors determines if struvite would be effectively precipitated in groundwater. This study identified the factors and mechanisms that hinder the recovery of P from groundwater through struvite precipitation. The findings of this study would be helpful in developing the strategies of P recovery from P-rich groundwater. KEYWORDS: Struvite; Phosphorus Recovery; Groundwater; Calcium; Iron
Rock fracture detection and identification in outcrop area based on improved YOLOv7
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230425
Abstract:
[Objective]The detection of rock fractures in the outcrop area is of great significance for the geological exploration of fractured oil and gas reservoirs, but the traditional image processing algorithm is not effective for the detection of rock fractures, the classical depth learning model is characterized by high complexity, slow convergence and detection speed, and low detection accuracy for rock fractures with complex geological background, therefore, this paper presents an improved outcrop rock fracture detection algorithm YOLOv7-PCN. [Methods]Firstly, PConv (Partial Convolution) Convolution module is used to replace the standard Convolution in the backbone network, resulting in reduced computational complexity and improved detection speed. Moreover, the integration of the Coordinate Attention (CA) mechanism further improves the feature extraction capability, especially for capturing key information from critical fracture locations. Finally, the bounding box regression loss function is measured by NWD (Normalized Wasserstein Distance), which optimizes the training convergence rate of the network, the location and detection accuracy of small target fracture with lower resolution in complex environment is improved. At the same time, in data processing, A dataset of rock fractures in outcrop areas is created using data augmentation techniques to enhance the generalization capability of the network model. [Results]Experimental findings reveal an impressive average accuracy of 82.5%, surpassing the original YOLOv7 algorithm by 7.7%. Furthermore, the model's parameters are significantly reduced by 29.6%, resulting in a 31.2% reduction in computational workload. Additionally, the model's detection speed is impressively improved by 39.2%, which proves the effectiveness of the improved algorithm model. [Conclusion]The proposed enhanced YOLOv7 algorithm for rock fracture detection in this paper integrates the strengths of traditional convolutional neural network models with advanced deep learning-based target detection models, with fewer parameters and reduced computation. As a result, it achieves a higher level of accuracy in detecting rock fractures even in challenging and complex environments. The algorithm successfully meets the requirements for both accuracy and real-time performance in rock fracture detection tasks.
Transfer learning and its application in solid Earth geoscience
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230429
Abstract:
As geoscience enters the era of big data, machine learning has become an emerging tool that can discover and describe complex structures and patterns of data, and is rapidly applied in the field of solid Earth geoscience. As an important subfield of machine learning, deep learning gradually learns massive amounts of data by constructing multi-level hidden layers, which can improve classification or prediction performance. However, most of machine learning models require massive amounts of data as support, which limits their widespread applications in the field of solid Earth geosciences. Transfer learning is a type of machine learning methods in the absence of adequate data, which aims to improve the performance of new tasks by using pre-trained knowledge of similar tasks in advance. By using the knowledge learned from the source domain and transferring it to the target domain, it can to some extent overcome insufficient data availability. This paper provides a brief overview of the basic concepts and categories of transfer learning, discusses the challenges faced by existing transfer learning approaches applied to geoscience by analyzing the typical cases of transfer learning in solid Earth geosciences. At present, deep transfer learning approaches have initially shown great potential in automatic identification and classification of rocks and minerals, identification of geochemical anomalies, etc. With the advantage of improving model generalization performance and avoiding overfitting, deep transfer learning approaches have broad application prospects in the field of solid Earth geosciences.
Research on characterization model for equivalent hydraulic aperture of nonmatching fracture based on MIC
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230443
Abstract:
Equivalent hydraulic aperture can quantitatively characterize the hydraulic conductivity of rough fractures under Darcy flow conditions, accurately predicting the equivalent hydraulic aperture is of great importance for many practical engineering applications. [Objective]The equivalent hydraulic aperture of rough fractures is influenced by complex geometric features such as wall surface topography and aperture distribution. This study comprehensively consider the geometric information of fractures, use the maximal information coefficient (MIC) method to determine the key controlling factors of the equivalent hydraulic aperture, and establish a characterization model for the equivalent hydraulic aperture of rough fractures based on these key factors. [Methods]First, based on the Barton's 10 standard curves, 900 sets of nonmatching rough fractures were constructed, the geometric information of the wall was used to obtain 13 geometric parameters and the equivalent hydraulic apertures of all fractures were obtained through direct numerical simulations. Then, the maximal information coefficient method was employed to analyze the correlation between the equivalent hydraulic aperture and 13 geometric parameters, [Results]as a result, 4 major controlling factors were identified, based on these factors, a characterization model for the equivalent hydraulic aperture of rough fractures was established. [Conclusion]Based on the data of 900 rough fractures, two existing models for representing the equivalent hydraulic aperture were selected for comparative analysis, the analysis results showed that the hydraulic aperture model proposed in this study exhibited better characterization performance compared to the existing models. Finally, the study investigated the influence of size effects on establishing an equivalent hydraulic aperture representation model, and discussed the methods of extending the research of this paper to three-dimensional fractures.
Mechanism of CO2/N2 stripping shale oil based on molecular dynamics simulation
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230456
Abstract:
Abstract:[Objective]The aim of this research is to investigate the storage state of tight oil and the mechanism of its replacement by CO2 using molecular dynamics simulations.[Methods]The Monte Carlo method and molecular dynamics simulation algorithms were employed to model the storage state of alkanes of varying molecular weights on rock surfaces. These models helped to examine the storage characteristics of alkane molecules on different types of rock surfaces and to analyze the micro-mechanisms of tight oil replacement by CO2 and N2. The simulated temperature and pressure conditions were selected to tight reservoir in the Sichuan basin (343.13K, 20MPa).[Results]The measured diffusion coefficients of C7 in CO2 were 1.88×10-5 and 1.83×10-5 on quartz and calcite surfaces, respectively. In contrast, the coefficients were lower in N2, at 6.4×10-6 and 9.01×10-6, respectively.[Conclusion]The findings indicate that CO2 is significantly more effective than N2 in replacing tight oil. The difficulty of displacing alkane molecules from rock surfaces increases with the relative molecular weight. As the relative molecular weight increases, it becomes more challenging to displace alkane molecules from the rock surface, and the adsorption of alkane molecules on the calcite surface is stronger than on the quartz surface. Based on the experimental results presented in this paper, the CO2 replacement mechanism can be broadly categorized into four stages: molecular diffusion, competitive adsorption, emulsification and dissolution, and a mixed-phase stage (involving low molecular weight alkanes).
Risk assessment of landslide geological hazards under different rainfall conditions based on P-III curve
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230472
Abstract:
[Objective] Rainfall is one of the important factors that induce geological disasters such as landslides and collapses, posing a great threat to the safety of people's lives and property. Therefore, it is necessary to take effective prevention and control measures as well as to avoid and relocate. [Methods] This article takes Yezhi Town as the study area, the grid unit is used as the evaluation unit. 9 evaluation factors including elevation, land use type, slope, aspect, elevation, landform type, engineering geological rock group, land use type, distance from river, distance from fault, curvature were selected. Using Pearson correlation analysis, the correlation between the 9 factors is weak, can participate in subsequent calculations. The Random Forest algorithm was used to analyze the feature importance of 9 factors, based on the feature importance, obtain a weighted information model that combines subjective and objective factors, using this model as a susceptibility evaluation for collapses and landslides. Then select rainfall as the risk assessment factor. Predicting the rainfall of the study area once in 10 years, once in 20 years, once in 50 years, once in 100 years through calculation and P-III curve, and import the data into ArcGIS, utilizing the raster calculator function, four different rainfall conditions were obtained. Then superimposing the rainfall conditions and the susceptibility assessment model to obtain the risk assessment. [Results] According to the statistics, he susceptibility assessment results are divided into four levels using the natural discontinuity method: low, medium, high, and extremely high susceptibility areas, which occupied 32.8%, 34.02%, 21.96% and 11.22% of the study area respectively. ROC curve was used to verify the accuracy, and the AUC value was 89.2%, falling into a better range. The risk assessment results of the four rainfall conditions were divided into four grades according to a certain range: low, medium, high and extremely high risk zones. The results of geological hazard risk assessment under different rainfall conditions is determined. [Conclusion] By comparing with the actual investigation, the landslide and collapse risk assessment results under different rainfall conditions are highly consistent with the actual situation. This article can provide a basis for reasonable disaster prevention and mitigation, as well as risk avoidance and relocation. Subsequently, a comparative analysis will be conducted on the selection of evaluation units to select the most suitable evaluation unit for the study area. I will also apply InSAR to identify hidden danger points of geological disasters in high altitude areas that are difficult for people to reach in the study area, and apply hidden danger point data to the susceptibility evaluation and risk assessment system.
Landslide Susceptibility Assessment in the Alpine and Canyon Areas based on Ascending and Descending InSAR data
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230560
Abstract:
[Objective]In recent years, Interferometric Synthetic Aperture Radar (InSAR) data reflecting surface deformation factors have gradually been introduced into landslide susceptibility assessment as factors reflecting surface deformation. However, these studies did not consider differences in SAR images. Especially in the alpine and canyon area, the imaging effect of InSAR ascending and descending varies greatly, and there is a large error in the response to surface deformation. [Methods]In this paper, the reservoir area of Xiangbiling Hydropower Station was selected as the research area. After the correlation analysis of index factors, 11 inducing factors and InSAR deformation data related to landslide in alpine and canyon areas were selected for landslide susceptibility evaluation. [Results]Comparing whether to use deformation data and using different deformation data, it is found that supplementing the sparse ascending data of sampling points in the susceptibility evaluation will reduce the accuracy of susceptibility evaluation, and the descending SAR data with more sampling points can improve the susceptibility accuracy by 2.7% to a certain extent (AUC=0.9248).[Conclusion]Therefore, the introduction of InSAR deformation data as a factor in landslide susceptibility assessment will affect the evaluation results, and it is necessary to select appropriate InSAR deformation data to improve the accuracy of susceptibility evaluation.
Study on spatial distribution of earthquake-induced landslide in densely populated area of the Luding 9.5 earthquake
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230619
Abstract:
On September 5, 2022, an earthquake with Ms6.8 occurred in Luding County, Ganzi, Sichuan Province, causing heavy casualties and economic and property losses. Because the earthquake-stricken areas are mostly mountainous and canyon landforms and dense vegetation, it is difficult to investigate geological disasters on the artificial ground, and it is difficult to accurately identify the landslide boundary under high vegetation coverage by satellite images. Therefore, in order to deeply understand the spatial distribution characteristics of this earthquake-induced landslide, this paper provides a visual interpretation of the coseismic landslide based on the 0.2m resolution optical image (DOM) obtained after the earthquake, and then the boundary of the coseismic landslide under the vegetation layer is corrected by using the digital elevation model (DEM) with a resolution of 0.5m, at the same time, the potential earthquake landslide under the vegetation layer is interpreted, combined with the field investigation, 9248 landslides induced by this earthquake are finally obtained, with a total area of about 45.57km2. On this basis, the relationship between the geological background such as topography, geological structure and seismic factors and the distribution of coseismic landslides is analyzed, aiming at providing an important basis for the investigation of hidden dangers of geological disasters in disaster areas, disaster assessment and site selection for post-disaster resettlement, as well as providing an important foundation and guarantee for post-disaster reconstruction and geological disaster prevention.