基于破坏概率法的降雨型滑坡失稳破坏分析

Analysis of Instability and Destruction of Rainfall Type Landslide Based on Failure Probability

精准分析降雨型滑坡的稳定性,有利于深化对该类型滑坡灾害的评价和预测预报,但传统方法计算滑坡稳定性不仅忽略了计算参数的随机分布对滑坡产生的影响,也无法得出滑坡的失稳概率。以韶关地区典型的降雨型滑坡为例,建立降雨型滑坡分析模型及稳定性系数计算模型,再基于Monte-Carlo法,将破坏概率分析法结合剩余推力法运用到模型中,对研究区降雨型滑坡在天然工况和暴雨饱和工况进行了稳定性分析及破坏概率计算。结果表明:滑坡在天然工况下基本稳定,破坏概率范围为31.3%~37.1%,处于中等偏低危险等级;在暴雨饱和工况下下欠稳定,破坏概率范围为51.6%~55.3%,处于中等偏高危险等级;破坏概率分析法与传统计算方法相比,同样能够得到准确的滑坡稳定性评价结果,并且在计算中更为简便合理;采用破坏概率分析法计算时,不考虑岩土体参数变异系数及偏度系数计算的滑坡破坏概率较考虑岩土体参数变异系数及偏度系数计算的破坏概率偏高,两者计算结果差距范围为5%~20%。

Accurate analysis of the stability of rainfall-type landslides is conducive to deepening the evaluation and prediction of this type of landslide hazard. However, the traditional method of calculating landslide stability not only ignores the influence of the random distribution of calculation parameters on the landslide, but also fails to derive the landslide. Taking a typical rainfall-type landslide in Shaoguan area as an example, we established a rainfall-type landslide analysis model and a stability coefficient calculation model. Based on Monte-Carlo method, combined with failure probability analysis method and residual thrust method, the stability analysis and failure probability calculation of rainfall landslide in the study area were carried out under natural conditions and rainstorm saturation conditions. The results show that the landslide is basically stable under natural conditions, and the damage probability ranges from 31.3% to 37.1%, which is at a medium to low risk level;it is not stable under the saturated rainstorm conditions, and the damage probability ranges from 51.6% to 55.3%. which is at a moderately high risk level;compared with the traditional calculation method, the failure probability analysis method can also obtain accurate stability evaluation results, and the calculation is more simple and reasonable;when the failure probability analysis method is used, the failure probability calculated by not considering the variation coefficient and the skewness coefficient of the rock and soil parameters is higher than the failure probability calculated by considering these parameters, and the difference between the two calculation results is about 5% to 20%.