考虑浸润线不确定性的边坡可靠度分析方法

Slope reliability analysis method considering the uncertainty of phreatic line

为了探讨浸润线不确定性对边坡失效概率的影响,利用一正态分布变量模拟了浸润线的随机变化,在软件Geo-Studio中建立边坡模型,编制python程序进行批量处理实现了考虑浸润线不确定性的边坡失效概率蒙特卡罗模拟过程。分析了:仅考虑土体参数不确定性(无浸润线);仅考虑土体参数不确定性(确定浸润线);仅考虑浸润线不确定性(确定土体参数);同时考虑土体参数不确定性和浸润线不确定性等四种工况下边坡失效概率,对比发现:工况1下,边坡失效概率最低;工况2下,边坡失效概率随着浸润线最高位置的抬升直线增加,浸润线最高位置每抬升1 m,失效概率增加0.05;工况3下,边坡失效概率随着浸润线位置的抬升迅速增大,呈非线性增长趋势;工况4下,在浸润线位置较高时,边坡失效概率介于工况2和工况3之间;在浸润线位置较低时,工况3得出的失效概率明显低于工况2与工况4,工况4略高于工况2。说明在浸润线位置较高时,工况3得出的失效概率偏大,而工况2得出的失效概率偏小,在浸润线位置较低时,工况3与工况2得出的失效概率均偏小,建议在涉水边坡可靠度分析时应同时考虑土体参数不确定性与浸润线不确定性。

In order to explore the influence of the uncertainty of the phreatic line on slope failure probability,a normal distribution variable is used to simulate the random change of the phreatic line.A slope model is established in Geo-Studio,and a Python program is developed for batch processing to perform Monte Carlo simulation of slope failure probability considering the uncertainty of the phreatic line.Four cases,i.e.(1)only considering the uncertainty of soil parameters(no phreatic line);(2)only considering the uncertainty of soil parameters(the phreatic line is deterministic);(3)only considering the uncertainty of the phreatic line(the soil parameters are deterministic);and(4)considering the uncertainty of both soil parameters and phreatic line,are considered to compare the failure probabilities of slopes.The comparative results show that the slope failure probability is the lowest under case 1.Under case 2,the slope failure probability increases linearly with the lifting of the phreatic line,and the failure probability rises by 0.05 for every 1 m lift of the phreatic line.Under case 3,the slope failure probability increases rapidly with the rise of phreatic line at a nonlinear growth rate.The slope failure probability of case 4 is just between that of case 2 and case 3 when the phreatic line is at relatively high level,whereas the slope failure probability of case 3 is lower than that of case 2 or case 4 and the probability of case 4 is higher than that of case 2,when the phreatic line is at relatively low level.The comparison under case 4 indicates that the failure probability obtained under case 3 is relatively high,whilst the failure probability obtained under case 2 is relatively low when the phreatic line is at relatively high level.Case 2 and case 3 tend to give a low failure probability when the phreatic line is at a relatively low level.It is suggested to consider the uncertainty of both the phreatic line and soil parameters in the reliability analysis slopes.