China is one of the countries with the most serious landslide disasters in the world. Major landslides seriously threaten people's lives and property and influence the implementation of major national strategies. Accurate and reliable landslide prediction is the premise of disaster prevention and mitigation, and it is also a significant worldwide scientific issue that needs to be solved urgently. Aiming at predicting major landslides, this paper focuses on the core scientific issues of landslide evolution processes, and physical-mechanical mechanisms, and condenses three key scientific issues: landslide initiation correlation mechanisms, landslide initiation physical-mechanical mechanisms, and the theory of landslide process prediction. To solve these issues, the following research ideas are proposed: based on large field experimental sites and guided by system theory, cybernetics, and information theory, technical means, including on-site prototype testing and monitoring, large-scale physical model testing, and multifield coupling simulation, which are applied to determine the initiation classification of major landslides according to the landslide evolution process; the physical-mechanical mechanism of locked-segment unlocking-type landslides, static liquefied-type landslides, and hydrodynamic pressure-driven landslides are revealed; the corresponding initiation criterion is established; the numerical prediction mode and real-time forecasting platform for major landslides are constructed; landslide prediction theory based on physical-mechanical processes is established. It will lay the geological, mechanical, and physical foundation for the prediction of the above three types of landslides, ensuring the successful smooth implementation of major national strategies while meeting the major national needs for disaster prevention and mitigation.

Landslide forecasting and prediction is a frontier scientific issue that has received widespread attention in the field of geohazard prevention and control. The current research framework focuses on the deformation behavior characteristics and external dynamic factors of landslides and faces the dual bottleneck problems of low universality and low prediction accuracy.Based on the current research status, this paper systematically clarifies the connotation of the rheological-mechanical behavior and strength weakening effect of the sliding zone, explicates the evolution mechanism of the progressive failure of the landslide, summarizes the types of landslide prediction models, and introduces the typical models among them.Based on the comprehensively existing achievements, it is pointed out that the main problems of the current research are: ①the physical-mechanical models of landslide evolution are required to be extended; ②the prediction and forecasting models fail to fully integrate with landslide evolution and physical-mechanical model; ③the compatibility problem between physical-mechanical model prediction and multi-field monitoring data have not been practically solved. Given the above problems, the challenges of landslide prediction and forecasting models based on physical-mechanical processes are elaborated. Based on multidisciplinary integration and intersection, a new research strategy for landslide forecasting study is proposed. The new strategy requires the establishment of a physical-mechanical model of the landslide evolution process based on the structural properties and rheological-mechanical behavior of the slip zone. On this basis, a numerical forecasting mode for landslides is established by closely integrating real-time multi-field monitoring data that enables real-time dynamic updating of landslide physical-mechanical processes. This strategy is designed to achieve a theoretical and technical breakthrough.

Currently, double reduction method (DRM) is widely used in the field of slope stability. However, one of the main challenges of the double reduction method is how to define the comprehensive safety factor based on two reduction parameters. The trajectory reduction method developed by Isakov can be used to ensure the minimum comprehensive safety factor on different conditions. However, its main shortcoming is that the method needs expensive calculation to determine the safety factor for a certain slope configuration. The paper examines the relationship between the comprehensive safety factor and cohesive and internal friction angle of soil, by using the FEM and trajectory method to calculate the minimum safety factor and corresponding reduction factor with respect to different inclinations of the slope. The initial strength effect on double reduction parameters are analyzed accordingly. The result shows for a certain slope configuration; the initial strength has little effect on the critical strength which is related to the minimum comprehensive safety factor. It means that for a slope with a certain inclination, even if the strength of soil is different, the critical strength is identical. The critical strength of soil slope is linear with the inclination of the slope, which means that every inclination corresponds to one critical cohesive and one critical internal friction angle. Consequently, a novel method to calculate the minimum safety factor is proposed in this paper. The result obtained by this method is close to the result which is from the limit equilibrium method, and compared with the original method by Isakov, this alternative method can simplify the calculation, and keep the result as accurate as the limit equilibrium method. Thus, it can be used to analyze the stability of slope.

Due to the influence of reservoir water level, rainfall and geological conditions, the Three Gorges Reservoir area is a landslide hazard-prone area, and the landslide genesis mechanism and evolution process are also extremely complex.By taking the Xinpu Xia'ertai landslide as an example, this paper summarizes and analyses the resurgence law of large palaeo-landslides based on multiple sources of data, such as GPS displacement monitoring data, fracture data, rainfall and reservoir water level, and through a geotechnical creep compression model. The paper also verifies the mechanism of fracture formation on the trailing edge of the displaced landslide.The results show the following: ①Rainfall is the dominant factor of landslide deformation. Landslide deformation causes the landslide body to produce cracks and form rainfall infiltration channels, which intensifies rock fragmentation and weak layer mudification and reduces landslide stability; besides, concentrated and continuous rainfall can destabilize landslides. ②By comparing the predicted value of the model with the surface monitoring data, it is feasible to take annual rainfall as the controlling factor in the medium- and long-term landslide prediction model and help to improve the prediction accuracy of landslides. ③Pushing landslide trailing edge cracks consist of landslide pushing displacement and geotechnical body compression. In this paper, the compression creep model is introduced to calculate the crack width and compare it with the monitoring data. This shows that the compression creep model is suitable for this type of slope, and the average deformation modulus of the geotechnical body is obtained by applying the backpropagation of the geotechnical body creep compression model. Thus, we judge the degree of rock fragmentation, which provides a reference for landslide stability analysis and subsequent engineering management.

Huanggang is one of the areas with frequent geological disasters in the flood season in Hubei Province. The main types of geological disaster are landslides, accounting for 75% of rainfall-induced landslides. Therefore, this paper statistically analyzes the correlation between rainfall and landslides in Huanggang City over the last 10 years, studies the rainfall threshold of rainfall-induced landslides in Huanggang City based on considering the prone zoning of geological disasters, establishes the effective rainfall model of landslide occurrence by using the logistic regression model and then puts forward the corresponding meteorological early warning criterion for different prone zone areas. Finally, the rationality and reliability of the early warning criterion are tested by historical rainfall and landslide events. The results show that the meteorological early warning criterion established significantly improves the accuracy of meteorological early warning for rainfall-induced landslides in Huanggang City, provides refined technical guidance for disaster transfer, and effectively reduces the loss of life and property caused by rainfall-induced landslides.

Slope kinematics is normally used to evaluate the temporal and spatial evolution of landslides. The inverse velocity method (INV) is an important tool for predicting the initiation of landslide, but its correlation with the physical and mechanical mechanisms of multiple physical fields inside the landslide need to be further clarified. In this paper, the slope deformation and geological characteristics of the Lijie Beishan landslide in Zhouqu, Gansu Province was investigated. The inverse velocity method, velocity threshold method and numerical simulation based on unsaturated soil theory were used to study the kinematic characteristic of slope. The results showed that after the lowest value of the inverse velocity on June 3, 2021, a stable stage lasted for approximately 60 days and then suddenly accelerated on September 20. The velocity became more than 200 mm/d over 20 days, and the deformation did not converged. There was an obvious acceleration point in the time-dependent inverse velocity curve. The end of the landslide life cycle was obtained by extending the straight line after the onset of the acceleration point. The prediction period was within 8 days compared to the actual instability startup, and the landslide was predicted 130 days in advance. According to the post analysis of the whole time-dependent velocity curve, the multi-level speed thresholds of v₁=20 mm/d, v₂=60 mm/d, and v₃=100 mm/d were set up. Because there were two peaks of velocity, the prediction of landslide triggering was lagging compared to the inverse velocity method. The coupling of slope stresses, deformation and pore water transportation was simulated. The results showed that the inflection point of the time-dependent deformation curve was correlated with the increase in precipitation intensity, and the cumulative precipitation was negatively exponentially correlated with the safety factor. The cumulative deformation obtained by numerical simulation was 2 250 mm, the velocity of deformation was 10-35 mm/d, and the inverse velocity was 0.03-0.12 d/mm, which were close to the actual monitoring data. However, there was still a deviation between the prediction of the inflection point of slope deformation and the actual situation.

At approximately 20:30 on June 10, 2021, a high-speed landslide occurred in Pengjiadong in Xingren. The landslide mass moved at a high speed and scraped the slope collapse accumulation along the way, killed 3 people and damaged 18 houses. Through remote sensing interpretation of image data before and after the landslide, detailed geological investigation of the disaster site and indoor comprehensive analysis, the characteristics of the landslide were described in detail, and the movement characteristics and formation mechanism of the landslide were clarified. The research shows that the slope terrain with the feature of "steep up-moderate slow down-steep down" and the geotechnical structure with the feature of "hard up and soft down" were the internal factors of the landslide, while human engineering activities, saturated loading of heavy rainfall and infiltration softening were the external factors of the landslide. The plane shape of the landslide was polygonal. According to the movement characteristics and accumulation structure, the landslide was divided into three areas: sliding source area (Ⅰ), shoveling-circulation area (Ⅱ) and shoveling accumulation area (Ⅲ). The landslides was a high-speed compression-push landslide formed by the formation of dangerous rock zones, landslide initiation and slope collapse. The research shows that the in-depth study of the movement characteristics and disaster formation mechanism of the Pengjiadong landslide has a strong guiding role for disaster prevention and reduction in similar slope areas and geotechnical structure areas in Guizhou.

The stability evaluation of landslide is one of the key issues in the field of landslide prevention and control. The research on the landslide failure criterion can provide the support for the stability evaluation of landslides. In order to enhance the accuracy of landslide stability evaluation, the landslide failure criterion based on the monitoring data of deep displacement is an effective approach. Therefore, based on the deep displacement monitoring data of landslide, the sliding zone integrity index is introduced, and a directly proportional relationship between the integrity index of the sliding zone and the shear strength parameters of the landslide is deduced. By using the calculation method of landslide stability and the simplified model of debris landslide, a directly proportional relationship between the integrity index of the sliding zone and the stability coefficient of the landslide can be obtained. The instability failure criterion of the debris landslide in the Three Gorges Reservoir Area considering the integrity index of the sliding zone is established accordingly. In the case of the integrity index of the sliding zone is greater than the critical value, the landslide is in a stable state. Otherwise, in the case of the integrity index of the sliding zone is less than the critical value, the landslide is unstable. A typical debris landslide e.g. Wuchiba landslide in the Three Gorges Reservoir Area is analyzed in detailed as an example.It is found that the failure criterion is reliable and applicable for the Wuchiba landslide. The results show that the failure criterion of slip zone integrity index can be used to evaluate the stability of landslide, which can provide a new approach for the study of landslide failure criterion.

To explore the deep sliding instability mechanism of a soil slope, taking the subgrade slope instability at K1219+000 of the downward line of the Beijing-Guangzhou railway as an example, the deformation and failure characteristics, geomechanical process and instability causes of the soil slope are detailedly studied. The results show that the width and depth of cracks on the surface of the subgrade slope gradually become shallow and narrow from the top of the slope to the toe of the slope, and the deformation has a certain rotation, with obvious traction characteristics, which belongs to deep sliding and splitting instability. The soil slope has experienced three geomechanical processes: the redistribution of the stress field and seepage field caused by slope toe excavation and pumping, the increasing sliding force caused by rainwater infiltration softening and the deepening of the sliding surface, and the failure of retaining structure resistance. The mechanism of slope instability includes the stage of shallow sliding, the stage of shallow sliding surface moving to the deep layer, and the stage of deep sliding instability triggered by the dynamic load.On this basis, the position of the sliding surface is comprehensively determined and the mechanical parameters of the slip surface are determined by the inversion method. The regulation scheme of rigid frame double row anti-slide piles is adopted. Through theoretical calculation and numerical analysis, the deformation of slope and anti-slide piles are consistent with the deformation monitoring results, which indicates that the theoretical analysis of deep instability of soil slope is accurate and the calculation of mechanical parameters is scientific, and the measures are proven stable and reliable.

Rainfall infiltration and artificial excavation are important factors inducing the loess landslides. To study the deformation process of loess landslides in the Guanzhong area and its influence on stability under the two inducements, the Laomiao landslide in Yangchang Village, Changwu County, Shaanxi Province is taken as the research object.Through field investigation, geological mapping and borehole exploration, the deformation characteristics of the landslide are determined, and the deformation evolution process of the landslide is qualitatively analyzed. Based on the measured daily rainfall within 15 days before the landslide deformation, the process of landslide formation under continuous rainfall after excavation actions at the slope foot was simulated by using finite element software. Based on the strength reduction method, the stability variation law of the landslide is studied. The results show that: ① the special formation structure in the Guanzhong area is the internal cause of landslide deformation, and rainfall is the most important inducing factor; ②the deformation evolution process of the landslide: at first the slope was in a state of creep. After the excavation actions, the anterior edge of the slope became unstable, and then the trailing edge of the slope was drawn downward, resulting in tension cracks. Under the influence of rainfall, rainfall infiltrated along the fissures of the slope, while the shear strength of the rock and soil mass in the central part was reduced, resulting in the sliding interface between the soil layer and red clay layer. Ultimately a deep landslide was induced. ③ After the landslide excavation, the stability coefficient decreased by 0.102, as compared with the initial state. Then, influenced by continuous rainfall, the stability coefficient decreased slowly at an average rate of 0.010/d in the first 10 d, and rapidly decreased to the lowest rate of 0.034/d in 10-13 d, and began to rise after 13 d. The research results are expected to provide effective basis for the prevention and control of such landslides.

The deformation evolution of reservoir landslides of ten lags behind the variation in the reservoir water level during the operation of the Three Gorges Project, showing a deformation hysteresis effect, and the hysteresis effect is different with the difference in the permeability coefficient and fluctuation rate of reservoir water. Taking the Baijiabao landslide in the Three Gorges Reservoir area as an example, the variation law of the deformation lag time under different permeability coefficients k and reservoir water level decline rates v is studied by field investigation, monitoring data analysis and numerical simulation. The results show that when the permeability coefficient of the landslide is constant, the higher the decreasing rate of reservoir water level is, the more obvious the groundwater lag. When the reservoir water level drops at a certain rate, the greater the permeability coefficient of the sliding body is, the faster the groundwater drop.When the permeability coefficient of the sliding body is 0.85 m/d, the higher the rate of reservoir water level decline is, the shorter the deformation lag time of the landslide.The corresponding lag time is 3.74-9 d under different decline rates of the reservoir water level.When 0.47 < v/k < 1.18, 0.24 < relative deformation lag time < 1; when 1.18 < v/k < 2.38, 0 < relative deformation lag time < 0.24. When the reservoir water level decline rate is constant, the larger the landslide permeability coefficient is, the shorter the landslide deformation lag time is. Under different reservoir water level decline rates, the change rule of the relative deformation lag time with increasing v/k value is roughly the same, v=1.8 m/d, and the corresponding lag time of different permeability coefficients is 1.7-8 d. When 0.52 < v/k < 0.84, 0 < relative deformation lag time < 0.16; when 0.84 < v/k < 2.12, 0.16 < relative deformation lag time < 0.43; when 2.12 < v/k < 9, 0.43 < relative deformation lag time < 1. The research results have strong application value for the prediction and warning of reservoir landslides.

Water has an obvious degrading effect on the mechanical parameters of rock and soil.In this paper, triaxial tests of landslide deposits under different water content conditions were carried out, and empirical equations between saturation and mechanical parameters were established. Besides, secondary development on the established empirical equation was also carried out. Based the coupling of saturation and mechanical parameters, the influence of sliding body mechanical parameter changes on the landslide stability can then be considered in the process of real-time changes in reservoir water level.By comparing the simulation results of the Dahua landslide in Lanping County, Yunnan Province during the rise of the reservoir water level with the field monitoring data, the rationality of considering the water-induced deterioration effect of the mechanical parameters of the sliding body was verified.In the end, the engineering application of the deformation evolution law of the Dahua landslide considering water-induced deterioration was carried out.

To study the deformation destruction mechanism and stability of the Middle Pleistocene ice-water sediment landslide in the western Sichuan Depression, this paper takes the K1887+350 landslide in the Chengdu-Yaan section of the G5 Beijing-Kunming Expressway as an example. Engineering geological surveys, physical and mechanical tests, and comprehensive monitoring are applied. Based on the actual deformation of the landslide, the paper analyzes the deformation and destruction mechanism of the landslide and studies the stability of the landslide before and after the reinforcement treatment and comprehensive monitoring technology. The results show that an unfavorable geological structure, slope toe, and precipitation induction are the main reasons for the deformation and instability of the K1887+350 landslide. The swell ability of fine-grained soil in the Middle Pleistocene ice-water sediment layer further reduces the soil shear properties. The long-term infiltration of atmospheric rainfall eventually leads to the superficial creep-pull deformation of ice-water sediments. Surface crack monitoring is an effective way to judge the current state of a mountain and analyze the stability of a landslide.

Identifying the states of hydrodynamic pressure-driven landslides can more effectively assist in the analysis of the landslide deformation law, and accurately identifying the landslide state is of great significance for the in-depth study of the hydrodynamic pressure-driven landslide state. Aiming at the problem that there are few abrupt states of hydrodynamic pressure-driven landslides, it is difficult to obtain relevant features, which leads to poor state recognition performance, and a generative adversarial network learning method for landslide state recognition is proposed.In this method, the landslide state monitoring data matrix is constructed, a reasonable generator network is designed based on a small number of data samples to complete the data amplification of the landslide states, and the discriminator network is designed to realize the screening of the amplified data, and the classifying landslide states being realized through the confrontation generation network to achieve the purpose of landslide status identification. Taking the Baishuihe landslide in the Three Gorges Reservoir area as the research object, multisource monitoring data such as rainfall, reservoir water level, deep displacement, and surface displacement are normalized. The states recognition generative adversarial network completes the classification and identification of the landslide state. The results show that the generative adversarial network has high accuracy for landslide state recognition. The research method in this paper can accurately identify and classify the landslide state in the target area.

Hydrodynamic-driven bedding rock landslides are the focus of research in the field of landslide geological hazards due to their large number, frequent disasters, and excessive harm. However, the understanding of the initiation mechanism of landslides is still insufficient, and the accurate prediction of landslides still faces great challenges. Because of this, this paper takes moderate-dip angle bedding rock landslides with weak interlayers as the research object and conducts a series of landslide model tests under the action of hydrodynamics by constructing an ideal single-layer landslide physical model. On this basis, the macroscopic deformation evolution process of the landslide and the erosion degradation characteristics of the slide zone soil is analyzed in depth. The results show that the failure of bedding rock landslides is associated with the slip surface roughness and dip angle and can go through four stages: the initial deformation stage, uniform deformation stage, accelerated deformation stage, and failure stage.The seepage erosion in the sliding zone causes the loss of aggregates, which reduces the shear strength and causes the slope to slide. Simultaneously, the compression-shear action and the deformation of the overlying slope also adversely affect erosion strength.Based on the variation law of soil cohesion in the sliding zone with hydraulic gradient and erosion time, a seepage-driven evolution model of soil cohesion in the sliding zone is proposed, which can describe the degradation process of soil cohesion in the sliding zone well. The existence of sliding surface roughness not only significantly affects the deterioration law of the sliding zone, but also changes the failure modes of different regions of the sliding zone. By considering the influence of the roughness on the failure modes of different areas of the sliding zone, the multi-effect correlation analysis of dynamic water is carried out, and the mechanical model of the landslide is established, which realizes the effective evaluation of the dynamic stability of the landslide. The research achievements in this study can provide a theoretical reference for predicting and preventing actual hydrodynamic-driven bedding rock landslides.

The largest landslide triggered by the Wenchuan earthquake was the Daguangbao landslide, which formed in the preinterlayer structural dislocation zone (weak layer) in the slope. The weak layer suffered strong historical structural fragmentation and produced a large area of new fractures during the earthquake. The causes of weak layer fragmentation and its control effect on the initiation of the Daguangbao landslide have always been the research focus. In this paper, by taking the Daguangbao landslide as the geological prototype, the interlayer dislocation zone was generalized into a geological body model with a weak layer unit. Based on seismic wave ray theory, a dynamic response theoretical model of the vertical P-wave incidence process considering the wave field conversion and time delay at the top and bottom interface of the weak layer was established, and the dynamic stress amplification characteristics of the weak layer are found theoretically. Furthermore, through a shaking table physical model test, the influence law of seismic intensity and frequency on the stress amplification of the weak layer were revealed. Based on the theory and experimental structure, it was proposed that the amplitude attenuation was caused by the wave field conversion and energy distribution of the vibration wave at the top and bottom interface of the weak layer, and the time delay was caused by the difference in the medium properties between the weak layer and the upper and lower hard layers. Both of them lead to stress differentiation and superposition, which was the internal mechanism of stress amplification in the weak layer. Therefore, it was considered that the stress amplification of the preinterlayer structural dislocation zone of the Daguangbao landslide in the process of a strong earthquake led to the fragmentation of the rock mass in the zone, reduced the shear strength of the rock mass in the slip zone, and promoted the rapid start-up of the landslide in the process of a strong earthquake.

In the progressive failure process of multiple landslides, different parts of the slip zone have different yielding degrees and failure modes with different strength parameters. Under strong rainfall conditions, water-filled tension cracks generated on the slope surface give rise to hydrostatic pressure. The current widespread transfer coefficient method, which takes the same strength parameter for different locations of the slip zone, also has not yet taken into account the hydrostatic pressure effect. In this paper, we propose an improved transfer coefficient method which takes into account the hydrostatic pressure effect and the difference in strength parameters of different parts of the slip zone. The results show that, compared with the calculation method without considering the hydrostatic pressure and the difference in strength parameters in different parts of the slip zone, the anti-sliding force calculated by the improved transfer coefficient method is relatively small, the residual sliding force is relatively large, and the stability coefficients of landslides at all levels are reduced by approximately 33.26%, 17.92%, 24.95% and 16.94%, respectively. Based on the high stability coefficient before the improvement, it may lead to insufficient safety reserve of the retaining engineering. The improved transfer coefficient method proposed in this paper can provide a safer reference for multiple landslide disposal.

Periodic fluctuations of reservoir water level lead to the variations in seepage stress inside landslide bodies. Dynamic seepage pressures can lead to deterioration in the structure and strength of the slide zone, which affects the stability of the landslide. To identify the effect of seepage on the pore structure of the slip zone, the seepage tests were performed. First, a seepage test apparatus was developed and combined with CT scanning technology to obtain the meso-structure of the sliding zone under different seepage conditions. Then, the changes in the structural parameters of the slip zone soils were quantified by Avizo software. Finally, the mechanism of the meso-structural evolution of the sliding zone under seepage was analyzed. The results show that the permeability coefficient of the sliding zone decreases exponentially with time, and a higher seepage pressure will lead to a smaller permeability coefficient of the sliding zone. Statistical data show that the apparent porosity of sliding zone soil decreases from 5% to 1%. The proportion of pores with an equivalent spherical diameter of less than 80 μm increases with seepage time, while the proportion of pores with an equivalent spherical diameter greater than 80 μm decreases with seepage time. The above results indicate that the large pores in the slip zone soils are filled with small particles during the seepage.Hence, the seepage channels become elongated and curved, and the effective connectivity of the pores is weakened.

Under the action of continuous rainfall or excavation unloading, the strength index of soil deteriorates, but most of the current slope stability calculations directly regard it as a constant. To approach the real failure mode of slope instability, based on the Swedish slice method and the first-order linear strain-softening theory, this paper proposes a new method for slope progressive failure analysis, deduces the limit equilibrium expression of the strain-softening slope, and obtains the safety factor under the corresponding damage progress. Through the analysis of simulation examples, the feasibility of the slice-softening method is illustrated, and the calculation results show that the safety factor in the progressive failure process not only depends on the failure mode and strength parameters of the slope but is also closely related to the softening modulus of the rock and soil mass. At the same time, by comparing and checking the actual cases of the Danba landslide, it is confirmed that there are different attenuation coefficients for its strength index, that is, the attenuation coefficient of cohesion is greater than the friction angle. From theory to application, the finally obtained slice-softening method not only considers the strength degradation effect of rock and soil mass under the action of rainfall and the gradual development of sliding surface but can also effectively serve the stability analysis of slope under the background of practical engineering and provide guidance and suggestions for the prevention and treatment of landslides.

The limit analysis of slope stability has a relatively higher calculation efficiency and accuracy because it ignores the constitutive relation of materials. Compared to the limit equilibrium method, its assumptions are strict and realistic. In the classical upper bound limit analysis, the slope surfaces are required to be a regular straight line. However, the surfaces of natural or cutting slopes are normally nonlinear. In addition, the stability number N_s=c/γH is used to calculate the critical height of slopes without considering the external power caused by pore pressure. Different from the static equilibrium conditions adopted by the traditional limit equilibrium method, this paper aimed to evaluate the stability of slopes with nonlinear surfaces based on kinetic analysis. First, a method for determining the rotation center of landslides with nonlinear surfaces based on upper bound limit analysis and the principle of virtual work was proposed. Second, it was assumed that the sliding surface was a logarithmic helix, and the virtual work under gravity and energy equilibrium equation of slopes were established. Third, the stability coefficient K defined by the ratio of internal power to external power was proposed to evaluate the stability of the slope, and the results were compared with the Bishop method to verify its effectiveness. The influences of slope degree (β), internal friction angle (φ), cohesion (c) and pore pressure coefficient (r_u) on the stability coefficient K of different natural and cutting slopes were analyzed. The results confirmed that the stability of steep slopes would be improved by cutting. The stability coefficient K increased with increasing cohesion and decreased with increasing pore water pressure coefficient. When the impact of cohesion on the stability coefficient K was more significant than that on the pore water pressure coefficient, K increased with increasing internal friction angle (φ). In contrast, the stability coefficient K decreases with increasing internal friction angle (φ). The above results followed the general understanding of slope stability analysis, and the rationality of the model was verified. By comparing the calculation results with the Bishop method, it was found that the intension of the critical state represented by safety factor F_S=1 was the same as the stability coefficient K=0 defined in this paper. The stability coefficient K increased nonlinearly with increasing cohesion, which was in line with the progressive failure mode of the soil slopes.

Continuous water diversion irrigation has changed the structure of Malan loess, led to the reduction of the shear strength of the soil, and thus the frequent occurrence of landslides in the Heifangtai area, which seriously affected the lives and property safety of local residents. In order to analyze the infiltration process of Malan loess, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) tests were respectively carried out to investigate the permeability and structural damage microscopic characteristics for loess at different initial water contents and different dry densities. The obtained results show that the infiltration rate is negatively correlated with the initial moisture content of the soil. The density is negatively correlated, and it will take the lead to a higher water content area. The water content is higher, the increase in the proportion of micropores is smaller, and the less obvious the change in the contact mode between particles; the dry density of the sample is larger, the different pore volumes basically change in the same amount, the contact area is significantly reduced, and more overhead pores are formed, which are connected to each other, leading to good water storage capacity. After infiltration, the original dense structure of the sample is lost, and the particles are severely broken. Some slender particles evolve into nearly round particles or elliptical particles, and the contact mode between particles becomes point-edge contact.The intergranular cementation is damaged and destroyed, and even some particles in the aggregates are separated and fall off, resulting in the loss of soil strength and eventually leading to landslides. The results can provide a basis for the prevention and control of loess landslides.

Porosity is one of the important characteristics reflecting the microstructure of loess and directly affects the physical and mechanical properties of loess, such as water sensitivity, permeability and strength. To study the micropore structure characteristics of loess under hydraulic coupling, micro CT technology was used to scan the initial structure of natural undisturbed, undisturbed saturated and remolded loess and the soil structure after unconsolidated-undrained shear tests. The evolution characteristics of the pore structure before and after shear tests are analyzed through the three-dimensional structure model of loess. The results show that the pore structures of the natural undisturbed loess, the saturated undisturbed loess and the remolded loess are significantly different, and the pore structures of the samples have a significant impact on the shear failure process. The process of saturation and remodeling can reduce the macropores of undisturbed soil.Shear stress can cause shear failure of natural undisturbed and remolded loess, compression failure of undisturbed saturated loess, and the increases of local porosity. The natural undisturbed and undisturbed saturated loess show a large number of micropores and small pores before and after shear, and the pore dip angle is mainly distributed between 50°-90°, which explains the main reason for the formation of the metastable structure of loess. The remodeled loess has a uniform pore size distribution due to the disturbance effect, and the remodeled and saturated loess is more prone to buckling and yielding under hydraulic action. It is revealed that the microstructure of shear deformation and failure of loess is mainly manifested in the dissolution of intergranular cement, the collapse and filling of pores, and the rotation, fragmentation and slip of particles. The test results can provide a basis for the mechanism of shear strength reduction and collapsibility of loess.

The deformation of slopes is comprehensively controlled by many factors, and the sensitivity and action rules of different factors are obviously different in the deformation process. This article takes the bedding landslide in Yangxin County, Hubei Province as the research object. Through orthogonal experimental design combined with 3DEC (distinct element method, DEM), the sensitivity of multiple influencing factors to the deformation of bedding landslides is studied, and the dominant factors are established. Then, based on the response surface method to fit the quantitative relationship between the dominant factors and the deformation degree of different parts of the landslide, the influence law of the interaction of dominant factors on the deformation and failure mode of landslides is revealed. The study of the slope in the Yangxin County area shows that the slope and the strata dip are the dominant and secondary dominant factors affecting the bedding landslide, and the interaction between the two has a significant impact on the slope deformation. In the medium-steep bedding landslide, when the slope is less than the angle of rock, the slope deformation mainly concentrates on the slope top, and the degree of deformation increases with increasing rock dip, showing the slip-bending deformation failure mode. In a gently dipping bedding slope, when the slope is larger than the angle of rock, the displacement of the slope toe is more significant than that of the slope top, and the deformation degree of the slope toe increases with increasing slope, showing the slip-rupture deformation failure mode. This study can provide guidances for the prevention and control of such landslides.

Vegetation slope protection has become more popular in recent years as an environmentally friendly support approach for slope protection projects. Thus, it's critical to study how to properly plant vegetation to maximize its slope protection effect. As a result, this work uses arbor as the research object and 3D printing technology to construct a model of the arbor root. The slope protection effect of arbor was studied by using a self-designed landslide model test system and conducting systematic physical model tests with three different root arrangement modes and three different root spacings. The results reveal that: ①With tree roots supporting the slope, the peak value of anti-sliding force increases, the time to reach the peak value of anti-sliding force is substantially delayed, and anti-sliding force attenuation is reduced. ②Anti-arch arrangement>positive arch arrangement>linear arrangement>no root support in terms of anti-sliding force improvement. S=1.5D (root coverage range D=7 cm) has a similar improved impact to S= 2.0D, while S=2.5D has the highest peak value of anti-sliding force. ③In terms of the root arrangement mode, the anti-arch arrangement has the most obvious improvement effect on the slope displacement, while the positive arch arrangement and linear arrangement are close in terms of the improvement effect on the displacement. In terms of the root spacing, S=2.5D has the most obvious improvement effect on the slope displacement, while S=1.5D and S=2.0D are close in terms of the improvement effect on the slope. ④Under the linear arrangement, the slope's sliding range expands, whereas the positive arch and anti-arch arrangements effectively limit slope deformation. Root spacing has no obvious effect on the slope deformation field.In conclusion, managing the arrangement mode of trees and root spacing in the vegetation protection project can increase the slope protection effect.

Combined stabilizing piles are an effective measure to reinforce large-scale landslides with complex strata. However, the reinforcement mechanism of h-type stabilizing piles in composite strata, such as strata with upper hard and lower weak bedrock, still needs to be studied in depth. Based on a set of self-developed physical devices for landslide-h-type stabilizing piles in bedrock with upper hard and lower weak strata, monitoring of stress and strain, laser range finder, high speed camera, and particle image velocimetry (PIV) techniques were adopted to study the internal forces and displacement of h-type stabilizing piles in landslides bedrock with upper hard and lower weak strata and the deformation characteristics of landslides, through which the interaction mechanism between h-type anti-sliding piles and landslides were revealed. The results showed that under the loading at the tope of the landslide, the h-type stabilizing pile reinforced landslide exhibited progressive failure characterized by four stages of creep, constant-speed deformation, accelerated deformation, and failure. Influenced by the beam, the displacement of the pile head and front and rear piles is small, but the piles have the maximum strain near the sliding mass. The bending moment of the rear piles showed an "S" type distribution curve, while that of the front piles showed a triangular distribution curve, and the maximum negative bending moment occurred at a depth of 20 cm below the beam. With the increase in the volume content of the hard stratum (φ_β), the displacement of the pile head gradually decreased, and the maximum bending moment of the front and rear piles gradually decreased and tended to be stable as φ_β exceeded 60%. When φ_β was 20% and 40%, the soil pressure behind the rear piles showed a parabolic distribution curve; when φ_β was 60% and 80%, it changed to the reverse "S" distribution curve, and the second maximum value occurred near the sliding surface. The soil pressure behind the front piles showed a parabolic distribution type versus the change of φ_β. The results of this study can provide a theoretical reference for understanding the reinforcement mechanisms and design theories of combined stabilizing piles.

With the continuous development of highway construction in mountainous areas in China, an increasing number of highway slopes encounter fault crushed zones in complex geological structures. It is urgent to strengthen slopes with anti-slide pile structures. However, the traditional manual digging pile construction mode has several disadvantages such as high risk and low efficiency. In contrast, the combined anti-slide pile with circular section shows great advantages of high construction efficiency, safety and convenience. Therefore, it is of practical significance to explore its reinforcement effect on slopes with fault crushed zones. In this paper, five physical models of different thicknesses of broken zones and combined anti-slide piles with circular section are designed by using a home-made slope physical test system. The loading is applied on the slope top step by step. Pile strain, pile top position and soil pressure behind the pile are monitored during loading. A high-speed camera was used to capture the images of sliding body deformation and damage, which were post-processsed using PIV technology. Experimental research shows that the combined anti-slide pile with circular section can reinforce the slope by limiting the horizontal displacement of the sliding body behind the pile and confining the sliding body between the front and rear piles. The evolution of the sliding body can be divided into three stages: deformation compaction, accelerated deformation and failure slip. The ratio of the soil pressure behind the piles of the front and rear piles is between 1/3 and 1/2. The position of the maximum positive bending moment will move down after fracturing of the fault crushed zone. The thickness of the fault crushed zone affects the reinforcement effect of the combined section anti-slide pile with circular section. With the increase in the fault crushed zone thickness, the horizontal slip rate of the sliding body increases, the pile top displacement increases, and the maximum positive bending moment decreases. The bending moment and pile top displacement calculated by the model test and numerical simulation are in good agreement. The research results can provide a reference for the design of combined anti-slide piles with circular section in slope engineering.

Anchored slide-resistant piles are one of the main supporting structures for landslides. To date, there is still a lack of systematic studies on the characteristics of the mechanics and deformation of anchored slide-resistant piles in weak-hard interbedded strata. This study taking weak-hard interbedded strata as the geological background, based on the self-developed flexible inclinometer and automatic loading system, the test system was constructed. Model tests of landslides reinforced by anchored slide-resistant piles were conducted, and the force and deformation characteristics of piles, anchor cables, and sliding mass were revealed in the process of increasing loading force. The influence of the layout of anchor cables on the force and deformation of the pile-anchor was analyzed. The influence mechanism of the stratum with weak-hard interbedded rock on the anchored slide-resistant piles was analyzed by numerical simulation. In addition, the theoretical analysis was carried out by taking the double-anchored pile as an example. The results show that: ① in the landslide-pile-anchor system, the deep displacement of the pile and sliding mass decreases with increasing pile depth, the growth rate of the rear is greater than that of the middle in the sliding mass, and the growth rate of the sliding mass is greater than that of the pile. ② The thrust sharing ratio of the pile-anchor undergoes four stages, which is approximately 9∶1 when it becomes stable. Meanwhile, the bending moment of the pile is distributed in an "S" shape under the action of the anchor cable tension, and the positive and negative bending moments are asymmetrical. ③ The growth rate of the anchor cable tension increases with the increase in the anchoring angle, and the influence of different anchoring angles on the internal force of the pile is mainly reflected in the loaded section. ④ The multianchored pile structure can share more thrust than the single-anchored pile, and the maximal bending moment values of the double-anchored pile and triple-anchored pile are reduced by 22.41% and 40.55%, respectively. ⑤ Compared with the homogeneous stratum, the stress of the bedrock at the interface between a weak and hard rock in the weak-hard interbedded stratum changes abruptly, and the thickness ratios of the weak rock and whether the pile bottom is embedded in hard rock all affect the axial force of the anchor cable and the pile-rock interaction to varying degrees.Meanwhile, the theoretical value for the internal force of the double-anchored pile is closer to the test result. The study results of this paper can provide evidence for the optimal design of projects for landslides reinforced by anchored slide-resistant piles in weak-hard interbedded strata.

Variable rainfall intensity can influence soil permeability and saturation processes, change the mechanical properties of soil, and affect the initiation mode and damage scale of debris flows. To explore the response mechanism of debris flows under different rainfall modes after earthquakes, laboratory tests of artificial rainfall-induced debris flows was performed through a small-scale model trough and rainfall simulation system. Based on the starting process of debris flow under different rainfall patterns, the variation of water content and pore water pressure in the slope was studied. The results show that the landslide transforms to a debris flow under the increasing rainfall model, and the damage scale of the accumulation is the largest; the debris flow under the decreasing rainfall occurs after the backward breaking instability; the initiation of debris flow under uniform rainfall mode results from traceable erosion; local landslides are transformed into debris flows under the middle-peak rainfall pattern; under the Ⅴ-shaped rainfall pattern, the slope erosion is intensified and transformed into debris flow, with the smallest damage scale.The research results can provide reference for the forecast and warning of debris flow in Jiuzhaigou area.

In the construction of artificial freezing methods, the strength and deformation characteristics of frozen soil are crucial to the stability of frozen walls. To investigate the effect of different water contents on the strength and creep of the soil under freezing action after specimen preparation, the specimen was kept in an incubator for 24 hours, and the influence of moisture content on the strength and creep characteristics of Jiangxi red clay was studied by freezing triaxial tests at -10℃. The results show that the compressive strength of frozen red clay first increases and then decreases with increasing water content in the range of 16%-32%. In the range of 16%-28% water content, the cohesion increases and the internal friction angle decreases with increasing water content.The creep curves under confining pressures of 0.2 MPa and 0.5 MPa show that the red clay with a low water content only has a decay creep stage and stable creep.The results can be used as a reference for the artificial freezing method in the construction of subway tunnels in the red clay stratum in Jiangxi Province.

After a reservoir is filled with water, the gravel-soil of a slope is immersed, and the mechanical properties are changed, which affects the stability of the slope. To investigate the influence of immersion on the mechanical properties of gravel-soil, the gravel-soil at the back edge of the slope that has not been immersed was used and large-scale direct shear tests were performed to obtain the shear mechanical properties of gravel-soil after different immersion days. The test results show that after 40 days of immersion, the cohesion of gravel-soil decreases by 39% and the internal friction angle decreases by 8.3%; the cohesion of gravel-soil decreases significantly in the initial stage of immersion and the decay rate decreases with the increasing number of days of immersion.After 20 days of immersion, the cohesion does not decrease significantly with the increase of immersion days. To reveal the reason and mechanisms of shear reduction in gravel-soil, triaxial shear tests, laser particle size analysis and leachate cation analysis were performed on silty clay (fine-grained component of gravel-soil). The results indicate that the shear strength of gravel-soil is attenuated by mineral dissolution, ion exchange and adsorption of the silty clay in gravel-soil. The large particles in the soil are refined, and the cementation is reduced, which reduces the overall shear strength of the gravel-soil. This study has certain significance for the evaluation and management of gravel soil landslides in reservoir areas.

In view of the failure of rock anchors in spring thawing periods of seasonal freezing areas, this paper aims to investigate the anchorage ability of GFRP anchors under the action of freeze-thaw cycles.Through designing the physical model, loading tests were carried out on the test blocks experiencing 25, 50, and 75 freeze-thaw cycles.According to the test data and failure phenomena, the variation laws of the stress and bearing capacity of the GFRP bolt after freeze-thaw were analyzed.The results show that the freeze-thaw cycle will lead to a decrease in bonding performance between epoxy resin mortar and concrete. After 25, 50 and 75 cycles, the bearing capacity loss is 38.24%, 42.65% and 52.94%, respectively.The ultimate bearing capacity of the bolt decreases obviously with increasing freeze-thaw cycles. The freeze-thaw cycle accelerates the deterioration of the material properties of the bonding material and the surrounding rock. In the process, the load transfer to the interior is accelerated, leading to a reduction in the stress difference among points on the GFRP bolt, and the stress distribution of the bolt is more uniform than that at room temperature. Meanwhile, the deterioration of the material properties leads to local failure ahead of time, and the overall bearing capacity of the bolt is reduced.The research results can provide suggestions for the engineering application of GFRP anchor.

The treatment of aeolian sand subgrade has always been a difficult problem for desert highway construction.The geocell reinforcement method can provide a new path for desert highway construction. Combining the S21 line (Urumqi-Altay) desert highway subgrade field test, it is of great value and significance to study the dynamic response characteristics of different subgrade depths for the study of aeolian sand performance of geocelling reinforcement.The results show that ① The test speed has a great influence on the time-history curve fluctuation of dynamic stress, dynamic acceleration and dynamic velocity at different depths of the subgrade, and the peak values of dynamic velocity, dynamic acceleration and dynamic stress increase obviously with increasing speed. ②With the increase in the road base depth, the amplitudes of the dynamic velocity, dynamic acceleration and dynamic stress show a trend of gradual attenuation, among which the attenuation amplitude is the largest in the geocell-reinforced aeolian sand layer. ③ Along the horizontal direction of the cross section of the subgrade, the amplitude of the dynamic velocity, the amplitude of the dynamic acceleration and the amplitude of the dynamic stress attenuate exponentially. When the horizontal distance from the vibration source is 5 m, the amplitude attenuates to approximately 10%. This horizontal range can be used as a reference value for engineering design.

Lithology recognition through artificial intelligence and big data can provide effective assistance to relevant personnel in field investigations.To better promote the application of lithology recognition in professional fields, the deep learning recognition of big data based on rock images were performed through the steps of rock image acquisition, data preprocessing, migration learning, network building, network training and model testing in the northern mountain area of Chaohu.Based on previous work, a multi-scale lithologic identification method is proposed. A multi-scale model is established and given a certain weight according to the rock meso image.The comprehensive results are obtained by identification with the rock identification model. The local texture, particle size and other mesoscale information were used in the overall identification of rock lithology.The results show that the multi-scale method is helpful to improve the identification results. The accuracy of the model is above 95%, which can well identify the rock lithology.

Pipe jacking construction is widely used in urban construction due to non-excavation or less excavation, but the surface settlement caused by pipe jacking construction cannot be ignored. Relying on a pipe jacking project of a power tunnel in Foshan City, the law of surface settlement caused by pipe jacking construction was studied through field measurements, numerical simulations and Peck empirical formulas, and the effects of pipe-soil friction, grouting pressure and supporting pressure on the ground settlement were discussed. The results show that the lateral surface settlement caused by pipe jacking construction changes greatly within the range of approximately four pipe diameters from the axis, and the change in pipe-soil friction has a greater impact on the surface settlement within the range of approximately three pipe diameters from the axis. It has little effect on the surface settlement within the range of approximately one pipe diameter from the longitudinal ground surface to the excavation surface; the increase in grouting pressure can restrain the settlement of the surface. The surface settlement has a greater impact, and the research results can provide references for measures to control surface settlement caused by pipe jacking construction. At the same time, the measured value, simulated value and Peck's empirical formula have similar ground settlement trends and magnitudes, verifying the feasibility of numerical simulation and Peck's empirical formula in predicting surface settlement in actual projects.

To improve the accuracy of formation inversion by cuttings during tunnel geological investigation using horizontal directional drilling technology, this study focuses on the correlation of cutting transportation features and formation spatial locations based on a tunnel geological investigation project. This study mainly draws the following conclusions: The different cuttings' migration modes are determined according to the cutting's migration settling velocity, Fei Xiangjun's critical velocity theory, and Larsen's minimum return velocity theory. The migration of cuttings in the annulus is bedload, a small number of cuttings are suspended load, and the little remaining is cutting's bed. The newly generated cuttings at the drill bit tooface would come out as suspended load first with drilling fluid in the field. The cutting suspended moving mode was established based on the material transportation theory, the freesuspension, and the movement equations of cutting particles. According to the recorded data of carbonaceous slate cuttings and quartz schist cuttings, the resistance coefficient of the intact borehole wall during cutting movement is obtained, while the resistance coefficient of the fault zone is 2.72 times that of the intact zone. Then, the final suspended moving speeds of cuttings in the annulus for Φ140 mm and Φ168 mm drill rods are calculated, and finally, the correlation analysis calculation model for cuttings and formation is established.