降雨入渗对软土岸坡稳定性影响研究

Stability study of unsaturated soft soil slopes under rainfall infiltration

软土普遍具有含水率高、抗剪强度低的特点,且大多数的土体滑坡都发生在降雨期间或者降雨之后的某个时间,因此研究降雨入渗诱发软土岸坡失稳的机理具有十分重要的意义。选取某软土岸坡工程作为研究对象,基于有限元强度折减法,采用Abaqus软件建立三维软土岸坡有限元模型,分析降雨强度、时间以及饱和渗透系数对岸坡稳定的影响。结果表明:随着雨水的入渗,岸坡土体饱和度及孔隙水压力增大,土体浅层基质吸力减小或消失,导致土体抗剪强度降低,从而引起岸坡稳定性降低;降雨入渗诱发岸坡失稳的模式表现为渐近牵引式破坏,其塑性破坏区域最先出现在坡脚,并沿坡面向上发展,逐渐形成连续的塑性贯通滑动面;以及持续的强降雨最容易引发岸坡的失稳破坏。

Generally,soft soil has a high water content and low shear strength,and most of the soil landslides occur in the rain or during a certain time after the rainfall,so it is of great significance to study the mechanism of rainfall infiltration induced soft soil slope failure. This paper selects a soft soil slope engineering as the research object,based on finite element strength reduction,using Abaqus software to establish the three-dimensional finite element model of the soft soil slope,and analyzes the influence of slope stability on rainfall intensity and duration as well as saturated permeability coefficient. The results show that： Along with the rain infiltration the soil saturation and pore water pressure increase,the shallow soil matrix suction decrease or disappear,resulting in the reduction of soil shear strength and decrease of slope stability; The model of rainfall infiltration induced slope stability shows asymptotic traction damage,the plastic damage area first appears at the foot of the slope,and upwards along the slope face,and gradually forms a continuous plastic sliding surface; Continuous heavy rainfall easily leads to slope instability destruction.