强降雨入渗作用下土质边坡失稳灾变研究

Study on Catastrophe of Soil Slopes Under Rainfall Infiltration

公路边坡浅层垮塌是雨季最为常见的灾害现象,为了研究强降雨入渗作用下土质路堑边坡可能发生突发性失稳滑坡的机理,从实际工程出发以典型双层边坡为例,利用有限元程序ABAQUS对双层土质高边坡降雨入渗全过程中的孔压、应力、位移、塑性应变的变化进行了研究。结果表明:在强降雨条件下,地表水入渗将导致土体浅层的基质吸力减小或消失,土体表层竖向有效应力减小,表层土塑性应变峰值在降雨达到最大时出现;在降雨入渗的作用下,表层土的平均应力呈减小趋势,内部深层土平均应力与等效应力呈增大趋势,可能导致边坡浅层发生失稳,但随着后期降雨强度的减少,其最小应力会逐渐偏移屈服面;不同雨型作用下,边坡不同部位的位移响应差别较大;边坡失稳过程的塑性区呈两个方向向上延伸,一是沿着两层土的过渡区,一是沿着整个边坡滑动弧线,以过渡区为主。

Shallow collapse is the most common disaster during the rainy season.In order to study the influence of rainfall infiltration on the paroxysmal instability of soil slope,apractical double layer soil slope has been chosen to study its pore pressure,stress,displacement and plastic strain,which may be changed under the condition of rainfall infiltration in ABAQUS software.The analysis reveals that the matrix suction and vertical effective stress of shallow soil would decrease under the action of surface water infiltration.The peak value of plastic strain of the surface soil appears when the rainfall reaches the maximum.Under the action of rainfall infiltration,pressure stress of the surface soil would decrease,while the pressure stress and Mises stress of internal deep soil show increasing trend,which might cause instability of surface soil.In addition,with the decrease of rainfall,the pressure stress of surface soil would shift gradually yield surface.The different parts of the slope displacement would have great difference in the action of different rainfall pattern.In the process of slope failure,the plastic zone extends upwards along the transition zone between the two layer soils and slip curve of the slope,with the transition zone being the main one.