降雨条件下粗粒土高路堤渗流特性

Seepage characteristics of high grained soil embankment under rainfall condition

为了分析降雨条件下粗粒土高路堤的渗流特性,基于饱和-非饱和渗流理论,结合室内试验渗透系数数据与实际气候条件,对算例边坡在设计降雨方案条件下孔隙水压力、体积含水率以及暂态饱和区的变化规律进行研究。研究结果表明:在降雨过程中,一定深度内的边坡表层孔隙水压力与体积含水率逐渐增大;降雨停止后,孔隙水压力与体积含水率才开始沿着坡面向下逐渐恢复到初始状态;当降雨持续5 h时,路堤边坡表层及坡脚水平面会形成一定范围的暂态饱和区;降雨停止4 h后,暂态饱和区面积达到最大值374.5 m2;随着时间持续,暂态饱和区沿路堤边坡坡面迅速消散,暂态饱和区的形成与消散均表现出明显滞后特点;暂态饱和区的扩展深度与降雨时间呈正比例关系;在整个降雨过程中,雨水入渗对路面以下地下水位线影响有限。

In order to analyze the seepage characteristics of high fill coarse grained soil embankment under rainfall condition, the change law of pore water pressure, volumetric moisture content and transient saturated zone in slope example under the condition of design rainfall scheme was studied by the combination of laboratory field test data with actual climate condition based on saturated-unsaturated seepage theory. The results show that the pore water pressure and volumetric moisture content in the depth of the slope surface increase gradually during the process of rainfall. After the stop of rainfall, the pore water pressure and volumetric moisture content along the slope surface gradually restore to the initial state. At rainfall duration of 5 h, embankment slope surface and horizontal plane of slope toe form transient saturated zone in certain extent. After 4 h, the rainfall stops, the area of transient saturated zone reaches the maximum of 374.5 m2. For the duration of the rainfall, the transient saturated zone along the embankment slope surface dissipates rapidly, and the formation and dissipation of transient saturated zone shows a obvious lag characteristic. The formation of transient saturated zone is lagging behind the increase of pore water pressure and volumetric moisture content. Rainfall infiltration has definite effect on the groundwater line below pavement.