考虑不同降雨概率和雨型的滑坡渗流场及稳定性变化率特征

对各种工况下的滑坡稳定性演化规律进行研究具有重要意义。本文以贵州省思南县官寨滑坡的稳定性分析为例,首先通过泊松分布法计算出研究区每发生一次连续五天降雨的雨型及其累积降雨量的概率,再结合饱和-非饱和渗流理论和非线性有限元分析法,来探究雨型以及累积雨量对滑坡渗流场和稳定系数变化率的影响。结果表明：连续五天降雨包含的四种雨型中,先升后降型发生概率最大,先降后升型发生概率最小；连续五天累积降雨发生概率随降雨量的增大逐步递减。当累积降雨量一定时,滑坡浸润线变化趋势与各自对应雨型的降雨规律基本保持一致。边坡稳定性系数值在持续性降雨作用下逐步降低,其中累积降雨量一定时,下降型降雨作用下滑坡稳定性系数在前四天下降最多,上升降雨作用下滑坡稳定性系数下降最少。另外,上升型降雨作用下滑坡稳定性变化率逐渐上升,下降型降雨作用下稳定性变化率在逐渐下降,另外两种雨型作用下的稳定性变化率介于两者之间。

Analysis of underground seepage and stability of slope considering the probability of cumulative rainfall and rainfall type

It is of great significance to study the evolution law of landslide stability under various working conditions. In this study, Guanzai landslide in Sinan County of Guizhou province is selected as case study. Firstly, the Poisson distribution method is used to calculate the probabilities of each continuous five-day rainfall and its corresponding rainfall type. Then the saturated-unsaturated seepage theory and the nonlinear finite element analysis is combined to explore the effects of cumulative five-day rainfall and rainfall type on the landslide seepage and stability coefficient change raw. The results show that: in the four rainfall types of continuous five-day rainfall, the occurrence probability of rainfall that first rising and then falling is largest while the occurrence probability of rainfall that first falling and then rising is smallest; the probability of rainfall decreases along with the increase of cumulative rainfall. When cumulative rainfall is constant, the change raw of landslide seepage line is consistent with the rainfall raw of corresponding rainfall type. The landslide stability coefficient decreases along with the rain continues; When the cumulative rainfall is constant, the landslide stability coefficient decreases the most seriously in the former four days under the effect of falling-type rainfall while the landslide stability decreases the least under the effect of rising-type rainfall. In addition, the change rate of landslide stability coefficient gradually rises under rising-type rainfall while the change rate of landslide stability decreases under the falling-type rainfall, with the other two rainfall types fall somewhere in between.