降雨入渗条件下粗粒土路堤暂态饱和区发展规律及稳定性研究

A study of development law and stability of transient saturated areas of coarse-grained soil embankment under rainfall infiltration

为了分析降雨入渗条件下粗粒土路堤暂态饱和区发展规律及稳定性,结合工程实际及气象资料,通过拟定不同的降雨计算方案,采用饱和-非饱和渗流理论对粗粒土路堤边坡在不同降雨条件下雨水入渗过程进行数值模拟。研究结果表明:降雨过程中路堤边坡表面会形成一定范围的暂态饱和区,暂态饱和区的形成及发展过程与降雨强度及降雨时间密切相关;降雨入渗仅会引起路堤边坡坡面以下水位线的大幅上升,对路堤中部地下水位线影响较小;降雨停止后,路堤上部暂态饱和区迅速消散,而路堤中下部暂态饱和区消散过程则表现出明显的滞后特征,但总体而言暂态饱和区的面积呈下降趋势;降雨入渗将导致入渗区域内基质吸力的丧失与含水率的增加,是造成路堤边坡稳定性降低的主要因素,路堤的失稳形式表现为整体滑移与表面局部坍塌相结合。

In combination with the engineering fact and meteorological data,different rainfall calculation schemes are carried out in order to analyze the development law and failure mechanism of transient saturated areas of a coarse-grained soil embankment under rainfall infiltration condition.Based on the saturated and unsaturated seepage theory,a numerical simulation was conducted to examine the rain infiltration process of a coarse-grained soil embankment slope under different rainfall conditions.The results show that the transient saturated zone within a certain range forms in the embankment slope surface during the rainfall process,and the formation and development process of the transient saturated zone is closely related to rainfall intensity and rainfall time.Rainfall infiltration only leads water level under the surface of the embankment slope to rise sharply,and has less impact on the groundwater level of the central embankment.As long as the rain stops,the transient saturated zone from the top of embankment dissipates rapidly,while the middle and lower parts show the lagging characteristic.However,the area of transient saturated zone generally declines.The loss of matrix suction and the increase of moisture content in infiltration area due to rainfall infiltration are the main factors causing the embankment slope stability to decrease.The embankment form of instability is a whole sliding combined with partial surface collapse.