Abstract: It is universally acknowledged that soil strength degradation and creep under water-Absorption are main factors of startup of landslide.Taking Feng Jiaba landslide in Wushan as an example,owing to the physical and intensive parameters of loose soil with different saturation got from laboratory tests,the trend of stability evolvement of loose landslide under rainfall is got by using Finite Element Method to simulate through the software ANSYS.The results indicate that the point with maximum displacement is in the rear of landslide,and the value increases nonlinearly when the saturation of the soil arises.Plastic area occurs in the rear of landslide,and it enlarges continuously when the saturation arises.The stability of the landslide decreases when saturation arises,and it reaches minimum limit equilibrium state when the soil is complete saturation.As Feng Jiaba slope is at the state between instability and stability,it may develop into disaster with the permeability of prolonged continuous rainstorms and the water-dipping of Three Gorges Project's Ⅲ-phase.

Key words: loose soil landslide, rainfall, creep, strength degradation, saturation

摘要： 土体吸水蠕变强度衰减是散体滑坡演绎启动的根本原因,以巫山冯家坝滑坡为例,由室内试验得到不同饱和度下松散土体的物理力学参数,应用大型有限元数值模拟软件ANSYS,研究了降雨条件下散体滑坡的演变趋势。分析表明,滑坡的最大位移发生在滑坡体后缘,且随松散土体饱和度的增大呈非线性增大;塑性区主要分布在滑坡体后缘,随饱和度的增大,塑性区不断扩大,滑坡的稳定系数降低,达到饱和时,稳定状态接近极限平衡。冯家坝斜坡目前处于欠稳定状态,在长期暴雨和三峡Ⅲ期坝前水位浸泡共同作用下,很可能诱发滑坡形成灾害。

关键词: 散体滑坡, 降雨, 蠕变, 强度衰减, 饱和度