考虑土体参数非平稳特性下开挖边坡稳定性可靠度分析

Reliability Analysis of Excavated Slopes Considering Non-stationary Random Fields of Soil Parameter

基于极限分析上限法和随机场理论,采用蒙特卡洛模拟针对不排水条件下开挖边坡的稳定性开展可靠度分析。黏土不排水抗剪强度被模拟为非平稳随机场,并在参数敏感性分析中重点研究了非平稳程度和变异系数对边坡可靠度指标的影响。其中,将随机场中边坡的失效模式分为三类,研究了不同随机参数输入组合下每种失效模式的发生概率。结果表明边坡的可靠度指标随着非平稳程度的增加而增加,随着变异系数的增大而减小。结果显示,土体的空间变异性对边坡的失效模式影响显著。在考虑的随机参数组合下,失效模式以深部破坏模式为主,并且随着非平稳程度和变异系数的增加,深部破坏模式的发生概率逐渐降低,但坡趾破坏和深部坡趾破坏模式的发生概率增加。

Based on the upper bound limit analysis and random field theory,this paper investigates the reliability of excavated slopes in undrained conditions within the framework of Monte Carlo simulation.The soil undrained shear strength is simulated as random fields.The effects of degree of non-stationarity and coefficient of variation on the slope stability are highlighted in the parametric sensitivity analysis.The results indicate that the slope reliability index increases with the increase of degree of non-stationarity and reduces as the coefficient of variation increases.Meanwhile,the soil spatial variability affects significantly the failure mechanism of slopes.Under the combination of random parameters considered in this paper,the failure mode is mainly of deep failure.With the increase of degree of non-stationarity and coefficient of variation,the probability of occurrence for the deep failure mode gradually reduces and the probability of occurrence for the toe failure and deep toe failure modes increase accordingly.