填土边坡稳定性的可靠度分析

为了系统地建立填土边坡稳定性的可靠度分析方法, 首先, 在可靠度分析原理的基础上, 对填土边坡的不确定性进行了讨论; 然后, 建立了多变量影响下填土边坡可靠度分析的基本流程; 最后, 以广西平乐县二塘锰矿区典型填土边坡为例, 基于GeoStudio软件, 应用所提出的分析流程对典型填土边坡的可靠度指标进行了计算, 通过"安全概率"对边坡的安全性进行了评价.研究结果表明: (1)填土边坡的不确定性包括内部结构和环境因素两方面, 前者不确定因素来自于填土土体不确定性和边坡的几何特征不确定性, 后者不确定性因素来自于降雨、地震和人工加载等; (2)可靠度分析的基本流程为填土边坡系统不确定性分析、建立可靠度极限状态方程、求解可靠度指标和边坡安全性评价; (3)广西平乐二塘锰矿填土边坡敏感性因素排序为: 内摩擦角Φ＞黏聚力C＞车辆荷载F; (4)考虑50年一遇极值降雨过程, 稳定性系数在降雨12 h达到最小, 其可靠度指标(β)为8.79, 破坏概率为0.根据《滑坡防治工程设计与施工技术规范》所规定的安全系数, 填土边坡的安全概率为69.84%. 

Reliability Analysis of Stability of Fill Slope

In order to analyze reliability of the stability of fill slopes, first, uncertain factors of stability of slope are discussed on the basis of the reliability theory. Then, the basic process of reliability analysis of fill slope is established, considering multi-variables. Finally, we apply the proposed method to analyze typical fill slope in manganese mine located at Ertang village, Pingle county, Guangxi. Results show that the fill slope uncertainties include two aspects, namely, internal structure and environmental factors. The former is due to the uncertainty of soil and slope geometric characteristics, and the latter is due to the rainfall, earthquakes, artificial load and so on. The reliability analysis contains three steps including analyzing uncertainty of fill slope, establishing the equation of reliability analysis, calculating reliability index and evaluating slope safety. The sensitivity factors for analyzing slope stability is internal friction angle Φ > cohesion C > vehicle load F. When Considering the maximum rainfall of 50 years return period, the stability is lowest at 12 h in one rain course. Its reliability index (β) is 8.79 and the failure probability is 0. According to the safety factor of criterion, the safe probability of the fill slope is 69.84%.