基于可靠度理论的滑坡稳定性及其影响因素分析

Stability and its influential factors analysis of landslides based on reliability theory

基于可靠度理论,利用Morgenstern-Price法、Ordinary法、Bishop法和Janbu法等4类极限平衡方法对台州市北水南调工程朱溪引水段Ⅷ号滑坡的稳定性进行了分析,设计了最不利组合、最有利组合、平均值组合的确定性分析方案,目的是为可靠度计算结果提供对比基准;设计了Monte-Carlo循环次数为5 000,50 000,500 000,5 000 000次等4种计算工况,岩土参数的概率分布函数为正态分布、三角形分布和均匀分布等3种情况,方差等于0.5,1.0,2.0,3.0,4.0,5.0倍初始实验方差等6种计算方案,岩土参数间相关性在-1.0～1.0间按0.25等幅变化的9种情况。研究发现,循环次数仅对安全系极值有较大影响,对可靠度指标影响不大;分布函数和数据离散性均会对结果精度造成影响;参数相关性仅对失效概率造成较大影响。

Utilizing four kinds of limit equilibrium methods such as Morgenstern-Price,Ordinary,Bishop and Janbu,stability of the landslide No.8 in Zhuxi sector of Taizhou North-to-South Water Transfer Project is studied on basis of reliability theory.Determined analysis schemes of most harmful,most favorable and mean constitutions are designed to set reference points for probabilistic method.The influence of cyclic number on Mento-Carlo method is discussed under condition of cyclic numbers of 5 000,50 000,500 000,5 000 000.Then,the effect of probability distribution function such as normal,triangular and uniform is analyzed and tested.Furthermore,the effect of variance is reviewed on condition that standard deviation respectively equals 0.5,1.0,2.0,3.0,4.0 and 5.0 times of experimental value.Finally,sensitivity analysis and correlative coefficient between strength parameters from-1.0 to 1.0 change at intervals of 0.25 is considered.It is found that cyclic number only imposes great effect on extreme values of Fs,that different probabilistic distribution function and variance can do great harm to reliability indexes,and that correlative coefficient only exerts effect on failure probability.