Prediction of foundation bearing capacity based on grey Markov model
-
摘要:
地基是工程建设的基础,其承载力计算和预测十分关键,决定着建筑工程上部结构的安全性与稳定性。为实现小数据量、短周期、较高精度的地基承载力预测。本研究提出以地基静载试验数据为依据,利用灰色模型进行计算,结合马尔科夫优化,建立灰色马尔科夫预测模型,预测固定荷载作用下的地基沉降,进而明确相应沉降下的基地承载力。同时,将该模型与传统的灰色GM(1, 1)模型、指数曲线拟合模型进行对比,分析3种模型的优劣。结果表明,案例一中,静载试验下的地基承载能力完好,灰色马尔科夫模型、GM(1, 1)模型、指数曲线模型预测值与实测值的平均相对误差依次为1.55%,3.80%,10.22%,灰色马尔科夫模型精度最高,更契合地基静载试验,能准确有效地明确地基承载力;案例二中,地基在静载试验下发生破坏,破坏前灰色马尔科夫模型预测值与实测值的平均相对误差仅为0.5%,预测效果良好。破坏时,地基沉降迅速增加,加载点模型预测值与实测值的相对误差出现异常,骤增至26.29%,以此可判断破坏前一级加载序列荷载为该地基的极限承载力。运用此模型指导地基静载试验,在保障工程施工安全的前提下,相邻试验点可以适当减少静载试验次数,节约工程施工成本,为信息化地基静载试验提供一个新的计算工具。
-
关键词:
- 地基承载力 /
- 灰色马尔科夫模型 /
- 灰色GM(1, 1)模型 /
- 预测
Abstract:Foundation is the foundation of engineering construction, and its bearing capacity calculation and prediction are very critical indetermining the safety and stability of the superstructure of the building project. To realize the foundation bearing capacity prediction with small data volume, short period, and higher accuracy, this paper establishes the gray Markov prediction model to predict the foundation settlement under the action of fixed load and clarify the base bearing capacity, based on the foundation static load test data, the gray model for calculation, and Markov optimization. Meanwhile, the model is compared with the traditional gray GM(1, 1) model and exponential curve fitting model to analyze the advantages and disadvantages of the three models. The results show that in case one, the bearing capacity of the foundation underthe static load test is intact, and the average relative errors between the predicted and measured values of the gray Markov model, GM(1, 1) model, and exponential curve model are 1.55%, 3.80% and 10.22% in order, and the gray Markov model has the highest accuracy and fits the static load test of the foundation better, which can clarify the bearing capacity of the foundation accurately and effectively; in case two, the foundation The average relative error between the predicted and measured values of the gray Markov model before the damage occurred under the static load test was only 0.5%, and the prediction effect was good. When the damage occurred, the settlement of the foundation increased rapidly, and the relative error between the predicted and measured values of the model at the loading point was abnormal and increased to 26.29%, so that the load of the loading sequence at the first level before the damage could be judged as the ultimate bearing capacity of the foundation. Using this model to guide the foundation static load test, the number of static load tests can be appropriately reduced at adjacent test points under the premise of ensuring construction safety, saving the construction cost of the project, and providing a new calculation tool for the information foundation static load test.
-
Key words:
- foundation bearing capacity /
- grey Markov model /
- grey GM(1, 1) model /
- prediction
-
表 1 静载试验中地基荷载与沉降的实测数据
Table 1. Measured data of foundation load and settlement in static load test
加载序号 1 2 3 4 5 6 7 8 9 荷载/kN 92 138 184 230 276 322 368 414 460 沉降/mm 4.99 9.39 12.32 15.85 19.97 25.79 27.79 35.22 43.82 表 2 状态区域分布
Table 2. Distribution of state regions
加载序号 相对误差/% 状态划分 加载序号 相对误差/% 状态划分 2 -11.93 一 6 8.07 四 3 -4.55 二 7 -4.53 二 4 0.44 三 8 -1.11 二 5 3.15 三 9 0.41 三 表 3 状态预测计算
Table 3. State prediction calculation
加载序号 初始状态 转移步数 状态一 状态二 状态三 状态四 5 3 1 0 0 1/3 1/3 4 3 2 0 1/3 0 1/3 3 2 3 0 0 0 1/3 2 1 4 0 0 0 1 合计 0 1/3 1/3 2 表 4 3种预测方式的对比分析
Table 4. Comparative analysis of three prediction methods
加载序号 荷载/kN 沉降/mm 曲线拟合 灰色GM(1, 1) 灰色马尔科夫 测值 相对误差/% 预测值 相对误差/% 预测值 相对误差/% 1 92 4.99 8.03 60.92 4.99 0.00 4.99 0.00 2 138 9.39 9.94 5.86 10.51 11.93 9.64 2.66 3 184 12.32 12.30 0.16 12.88 4.55 12.50 1.46 4 230 15.85 15.22 3.97 15.78 0.44 16.10 1.58 5 276 19.97 18.83 5.71 19.34 3.15 19.73 1.20 6 322 25.79 23.30 9.65 23.71 8.07 25.22 2.21 7 368 27.79 28.82 3.71 29.05 4.53 27.41 1.37 8 414 35.22 35.67 1.28 35.61 1.11 34.57 1.85 9 460 43.82 44.13 0.71 43.64 0.41 44.53 1.62 平均相对误差/% 10.22 3.80 1.55 平均绝对误差/mm 1.07 0.70 0.36 表 5 静载试验中地基荷载与沉降的实测数据
Table 5. Measured data of foundation load and settlement in static load test
加载序号 1 2 3 4 5 6 7(破坏) 荷载/kN 160 240 320 400 480 560 640 沉降/mm 6.77 14.04 21.27 29.48 42.39 59.34 115.27 表 6 对加载序号1~4号的沉降值修正
Table 6. Correction of settlement value for loading sequence number 1-4
加载序号 实测值 预测值 修正值 1 6.77 6.77 6.77 2 14.04 14.56 14.14 3 21.27 20.59 21.23 4 29.48 29.13 29.42 表 7 2种预测模型的对比分析
Table 7. Comparative analysis of two prediction models
加载序号 荷载/kN 沉降/mm 灰色GM(1, 1) 灰色马尔科夫 预测值 相对误差/% 预测值 相对误差/% 5 480 42.39 41.2 2.81 42.47 0.19 6 560 59.34 58.27 1.80 58.86 0.81 7(破坏) 640 115.27 82.42 28.50 84.97 26.29 -
[1] 王忠凯, 徐光黎. 盾构施工对既有建(构)筑地基承载力影响及加固土体稳定性分析[J]. 地质科技通报, 2020, 39(4): 109-116. doi: 10.19509/j.cnki.dzkq.2020.0414Wang Z K, Xu G L. Effect of shield tunneling construction on bearing capacity of foundation of existing buildings and stability analysis of reinforced soil[J]. Bulletin of Geological Science and Technology, 2020, 39(4): 109-116(in Chinese with English abstract). doi: 10.19509/j.cnki.dzkq.2020.0414 [2] 谭松林, 王江. 老黏土地基承载力的确定[J]. 地质科技情报, 2007, 26(4): 76-78. doi: 10.3969/j.issn.1000-7849.2007.04.015Tan S L, Wang J. Determination of the bearing capacity of aged clay groundsill[J]. Geological Science and Technology Information, 2007, 26(4): 76-78(in Chinese with English abstract). doi: 10.3969/j.issn.1000-7849.2007.04.015 [3] 彭祎, 成建梅, 马郧, 等. 基于改进阻力系数法的悬挂式帷幕基坑渗流计算[J]. 地质科技通报, 2021, 40(4): 179-186. doi: 10.19509/j.cnki.dzkq.2021.0411Peng Y, Cheng J M, Ma Y, et al. Seepage calculation of foundation with suspended curtain based on improved resistance coefficient method[J]. Bulletin of Geological Science and Technology, 2021, 40(4): 179-186(in Chinese with English abstract). doi: 10.19509/j.cnki.dzkq.2021.0411 [4] Zhu M C, Li S Q, Wei X L, et al. Prediction and stability assessment of soft foundation settlement of the fishbone-shaped dike near the estuary of the Yangtze River using machine learning methods[J]. Sustainability, 2021, 13(7): 1-14. [5] Alencar A S, Galindo R A, Melentijevic S. Bearing capacity of foundation on rock mass depending on footing shape and interface roughness[J]. Geomechanics and Engineering, 2019, 18(4): 391-406. [6] Amin K, Jyant K. Bearing capacity of foundations on rock mass using the method of characteristics[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2018, 42(3): 542-557. doi: 10.1002/nag.2754 [7] 齐宏伟, 李文华. 基于BP算法的CFG桩复合地基承载力的神经网络预测[J]. 工业建筑, 2005, 35(增刊1): 525-528. https://www.cnki.com.cn/Article/CJFDTOTAL-GYJZ2005S1156.htmQi H W, Li W H. Neural net work prediction on bearing capacity of CFG pile composite foundation based on BP algorism[J]. Industrial Construction, 2005, 35(S1): 525-528(in Chinese with English abstract). https://www.cnki.com.cn/Article/CJFDTOTAL-GYJZ2005S1156.htm [8] Behera R N, Patra C R, Sivakugan N, et al. Prediction of ultimate bearing capacity of eccentrically inclined loaded strip footing by ANN, part I[J]. International Journal of Geotechnical Engineering, 2013, 7(1): 36-44. doi: 10.1179/1938636212Z.00000000012 [9] 加春燕, 李先印, 崔有祯. 基于"S-指数"数学模型的建筑地基沉降预测研究[J]. 工程勘察, 2019, 47(10): 63-68. https://www.cnki.com.cn/Article/CJFDTOTAL-GCKC201910012.htmJia C Y, Li X Y, Cui Y Z. Research on prediction of building foundation settlement based on S-exponential mathematical model[J]. Geotechnical Investigation & Surveying, 2019, 47(10): 63-68(in Chinese with English abstract). https://www.cnki.com.cn/Article/CJFDTOTAL-GCKC201910012.htm [10] Yin L H, Sun X D, Yang P, et al. Stability analysis for subgrade settlement prediction by curve fitting methods[J]. IOP Conference Series: Earth and Environmental Science, 2018, 170(3): 32-50. [11] 刘射洪, 袁聚云, 赵昕. 地基沉降预测模型研究综述[J]. 工业建筑, 2014, 44(增刊1): 738-741, 681. https://www.cnki.com.cn/Article/CJFDTOTAL-GYJZ2014S1181.htmLiu S H, Yuan J Y, Zhao X. Review of settlement prediction models of foundation[J]. Industrial Construction, 2014, 44(S1): 738-741, 681(in Chinese with English abstract). https://www.cnki.com.cn/Article/CJFDTOTAL-GYJZ2014S1181.htm [12] 朱定华, 陈国兴. 复合地基承载力的灰色预测[J]. 南京建筑工程学院学报: 自然科学版, 2001, 38(3): 32-36. https://www.cnki.com.cn/Article/CJFDTOTAL-NJJZ200103004.htmZhu D H, Chen G X. Grey Prediction of composite foundation bearing capacity[J]. Journal of Nanjing Architectural and Civil Engineering Institute: Natural Science Edition, 2001, 38(3): 32-36(in Chinese with English abstract). https://www.cnki.com.cn/Article/CJFDTOTAL-NJJZ200103004.htm [13] Tian J S. Prediction of engineering settlement and deformation based on grey theory model[J]. IOP Conference Series: Earth and Environmental Science, 2019, 218(1): 12-79. [14] 杨帆, 赵增鹏, 王小兵. 改进灰色马尔科夫模型在基坑预测中的研究[J]. 测绘与空间地理信息, 2017, 40(7): 15-18, 22. doi: 10.3969/j.issn.1672-5867.2017.07.005Yang F, Zhao Z P, Wang X B. Prediction of foundation settlement prediction based on improved grey markov model[J]. Geomatics & Spatial Information Technology, 2017, 40(7): 15-18, 22(in Chinese with English abstract). doi: 10.3969/j.issn.1672-5867.2017.07.005 [15] 郭清海, 王焰新, 武全胜, 等. 神头泉流量变化规律研究: 灰色系统理论的具体应用[J]. 地质科技情报, 2002, 21(1): 27-31. doi: 10.3969/j.issn.1000-7849.2002.01.007Guo Q H, Wang Y X, Wu Q S, et al. Research on discharge change rule of Shentou Spring: using grey system theory[J]. Geological Science and Technology Information, 2002, 21(1): 27-31(in Chinese with English abstract). doi: 10.3969/j.issn.1000-7849.2002.01.007 [16] 刘勇, 余宏明, 刘烽博, 等. 滑坡位移非线性时间序列预测模型研究[J]. 地质科技情报, 2016, 35(5): 203-207. https://www.cnki.com.cn/Article/CJFDTOTAL-DZKQ201605028.htmLiu Y, Yu H M, Liu F B, et al. Landslide displacement nonlinear time series prediction model[J]. Geological Science and Technology Information, 2016, 35(5): 203-207(in Chinese with English abstract). https://www.cnki.com.cn/Article/CJFDTOTAL-DZKQ201605028.htm [17] Wang Y, Dang Y, Li Y, et al. An approach to increase prediction precision of GM(1, 1) model based on optimization of the initial condition[J]. Expert Systems with Applications, 2010, 37(8): 5640-5644. doi: 10.1016/j.eswa.2010.02.048 [18] Wei B, Xie N, Hu A. Optimal solution for novel grey polynomial prediction model[J]. Applied Mathematical Modelling, 2018, 62(6): 717-727. [19] Markov A A. An example of statistical investigation of the text Eugene Onegin concerning the connection of samples in chains[J]. Bulletin of the Imperial Academy of Sciences of St. Petersburg, 1913, 7(3): 153-162 (In Russian). [20] Wang Y, Yao D X, Lu H F. Mine gas emission prediction based on grey markov prediction model[J]. Open Journal of Geology, 2018, 8(10): 939-946. doi: 10.4236/ojg.2018.810056 -