不同降雨强度下多台阶黄土边坡稳定性可靠度分析

Reliability Analysis of the Stability of a Multi⁃Stage loess Slope under Different Rainfall Intensities

为了研究降雨强度对黄土边坡稳定性、可靠度的影响,以某典型多台阶黄土边坡为研究对象,基于有限元软件分析了不同降雨强度下边坡的稳定性,进而考虑边坡土体强度参数的不确定性,采用响应面法和蒙特卡洛法计算了边坡失效概率,并探讨了黄土强度参数变异性和相关性对失效概率的影响。结果表明:不考虑边坡土体强度参数随机性将高估边坡稳定性系数;相较于黄土黏聚力,边坡失效概率对黄土内摩擦角的变异性更敏感,并随着内摩擦角变异系数的增大而呈现出非线性快速增大;此外,边坡失效概率还随着边坡主体离石黄土强度参数相关系数的增大而近似线性减小。因此,在开展边坡稳定性可靠度分析时,应更注重边坡主体结构土体强度参数变异性和相关性的影响。

To investigate the influence of rainfall intensity on the reliability of the stability of loess slopes,a typical multi⁃stage loess slope was selected to analyze the stability of slope under different rainfall intensities based on the finite element software.After considering the uncertainty of slope soil strength parameters,the slope failure probability was calculated using the Monte Carlo method.The influence of the variability and correlation of loess strength parameters on the failure probability was also discussed.The results show that the stability coefficient of multi⁃stage loess slopes decreases approximately linearly with the increase of rainfall duration at the rainfall stage,and slightly recovers at the infiltration stage.The influence of rainfall intensity on slope stability is relatively small.Omission of the randomness of the strength parameters of the slope soil will overestimate the factor of safety.Compared to the cohesion of loess,the probability of slope failure appears more sensitive to the variability of the internal friction angle of loess,and shows a nonlinear and rapid increase with the increase of the coefficient of variation of the internal friction angle.In addition,the failure probability of the slope also decreases approximately linearly with the increase of the correlation coefficient of the strength parameters of the main body of the slope soil.Therefore,more emphases should be placed onto the influence of the variability and correlation of the soil strength parameters of the main body of the slope,when analyzing the reliability of slope stability.