基于虚拟试验的边坡失稳概率分析方法

Instability Probability Analysis Method of Slope Based on Dummy Test

针对边坡稳定性分析中,极限平衡条分法得出的边坡稳定性系数表达式是一个高度非线性方程而导致可靠度计算无法进行的问题,按照复杂结构稳定可靠度求解思路,建立了以条分模式稳定性系数计算作为虚拟试验,以二次多项式为验算点逼近过渡函数,依据基本随机变量分析边坡稳定失效概率的方法。以陈祖煜-摩根斯坦边坡条分模式为例,阐明了在新方法中可靠度指标计算的步骤和精度控制及递归修正的实现过程。采用该方法计算了某公路边坡的失稳概率,并与精确解进行了比较。结果表明:该方法计算结果与精确解的相对误差为4.66%,绝对误差为0.535%,适用于边坡工程的失稳概率分析。

In the analysis of slope stability, reliability degree couldn＇t be calculated because slope stability coefficient expression calculated by limit equilibrium slice method of slope was a high order nonlinear equation. According to idea for reliability degree calculation for complicated structure, a new calculation method for failure probability of slope based on random variable was established. In the method, stability coefficient calculation for slope based on limit equilibrium slice mode was regarded as dummy test and quadratic equation was used to fit explict performance function. Taking Chen Zuyu-Morgenstern slope slice mode as an example, the calculative processes of the reliability index, precision control and realizing process of reeursion correction in the method were clarified. Compared with exact solution, this method was adopted to calculate instability probability of a highway slope. Results show that the relative error is 4.66% and the absolute error is 0. 535%. The new founded method fits for the instability probability analysis of slope engineering including highway and relative engineering.