降雨条件下层状土坡三维边坡稳定性分析  

Three-dimensional slope stability analysis of understory soil slope under rainfall condition

作　　者：韩同春[1,2] 吴俊扬 HAN Tong-chun;WUJun-yang(Department of Architecture and Civil Engineering,Zhejiang University,Hangzhou 310058,Zhejiang,China;Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,Zhejiang,China)

机构地区：[1]浙江大学建筑工程学院,浙江杭州310058 [2]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058

出　　处：《地基处理》2024年第3期223-234,共12页Journal of Ground Improvement

摘　　要：降雨是诱发滑坡的重要因素之一,在降雨型滑坡的研究中,关于土壤水分剖面形状动态变化对三维边坡稳定性的影响有待进一步考虑。鉴于此,在前人工作的基础上,本文采用含修正形状系数的形状曲线描述土壤水分剖面的变化,结合非饱和土的水力特性,计算等效渗透系数,推导出改进入渗模型并拓展至双层土体入渗。利用GRASS GIS建立三维边坡模型,选取椭球面作为三维滑动面,通过蒙特卡洛法模拟椭球面参数,确定试算滑动面,采用Hovland三维极限平衡法计算考虑雨水入渗影响的三维边坡安全系数。根据湿润锋面、土层间界面和潜在滑动面三者的相对位置关系,将栅格单元柱分为5种情况考虑。通过算例分析验证所提出的降雨条件下三维边坡稳定性分析方法的可行性,结果表明:蒙特卡洛模拟试算样本数的最佳取值可定为2500次;最小三维边坡安全系数随着降雨历时的增加而减小,减小幅度为0.055~0.126。Rainfall is a significant factor in triggering landslides.In the study of rainfall-induced landslides,the influence of dynamic changes of soil moisture profile shape on three-dimensional slope stability needs to be further considered.Therefore,based upon previous research,this work utilizes a shape curve with a modified shape coefficient to describe the variation of the soil moisture profile.Additionally,it integrates the hydraulic characteristics of unsaturated soil to compute the equivalent permeability coefficient,develop an enhanced infiltration model,and extend its application to double-layer soil infiltration.A three-dimensional slope model is constructed by GRASS GIS with an ellipsoid surface chosen as the sliding surface.The parameters of the ellipsoid surface are determined through Monte Carlo simulation to establish the trial sliding surface.The Hovland three-dimensional limit equilibrium method is adopted to calculate the three-dimensional slope safety factor considering the influence of rainfall infiltration.According to the relative position relationship among wetting front,soil layer interface and potential sliding surface,five different scenarios are considered in raster unit column.Through example analysis,the feasibility of the proposed method for analyzing the stability of three-dimensional slope under rainfall condition is verified.The results show that the optimal value of Monte Carlo simulation trial sample number can be set as 2500 times.Moreover,the minimum three-dimensional slope safety factor decreases with the increase of rainfall duration,with a reduction range of 0.055 to 0.126.

关 键 词：降雨入渗 土壤水分剖面 边坡稳定性分析 地理信息系统 极限平衡法 潜在滑动面 

分 类 号：TU43[建筑科学—岩土工程]