地震与降雨耦合作用下区域滑坡灾害评价方法

AN ASSESSMENT METHOD FOR REGIONAL SUSCEPTIBILITY OF LANDSLIDES UNDER COUPLING CONDITION OF EARTHQUAKE AND RAINFALL

基于莫尔–库仑破坏准则,通过引入地震动惯性力和地下水位系数,推导地震与降雨耦合作用下的滑坡安全系数计算公式。提出应用滑坡体物性、几何参数频度分析和蒙特卡罗模拟联合求算滑坡滑动概率的思路,建立综合坡度、土体类别、地震动强度和地下水位系数等因素的滑坡滑动概率理论判定矩阵。利用计算获得的特定研究区内不同强度地震动的重现概率,可将该矩阵转化为不同复发年限内实际地震发生条件下滑坡滑动概率的理论判定矩阵。依据2类理论判定矩阵,结合GIS技术、数字地质图和高精度DEM数据,即可实现地震与降雨耦合作用下区域滑坡灾害的概率性评价;以日本北九州市为例,给出应用该方法评价区域滑坡灾害的概率性预测结果。

Based on the Mohr-Coulomb failure criterion,a formula to calculate the factor of safety for landslide under coupling condition of earthquake and rainfall is deduced by introducing the inertia force of ground motion and groundwater factor.Then,by applying frequency analysis of physical and geometric parameters of slip mass and Monte Carlo simulation,a method to estimate sliding probability of landslides under coupling condition is developed.Consequently,the theoretical matrix,which considers influences of ground motion,slope angle,soil type and groundwater factor on sliding probability of landslides synthetically,is established to assess the risk probability of landslides under coupling condition.The earthquake,in fact,is a small probability event.For thinking over the occurrence probability of actual earthquake in any certain research region,it is better to calculate the repeated probabilities of ground motion according to its background seismicity.By the reoccurrence probabilities of ground motion,the above-mentioned theoretical matrix could figure the actual risk probability of landslides associated with earthquake events in any interesting region.According to the two kinds of theoretical matrixes,the probabilistic assessment for regional susceptibility of landslides under coupling condition should be achieved by GIS,data of digital geological map and high-precision DEM in a certain research region.As the case of Kitakyushu City,Japan,the procedure is applied to investigate the regional susceptibility of landslides under coupling condition in this city and the probabilistic assessment results are provided in the end.