降雨入渗条件下土质边坡含水率分布与浅层稳定性研究

A study of water content distribution and shallow stability of earth slopes subject to rainfall infiltration

设计一种可以测量土体体积含水率的降雨入渗试验模型,通过试验得到土体初始含水率分布状态以及降雨入渗条件下土体含水率变化规律。在此基础之上,结合非饱和土抗剪强度理论与极限平衡理论,得到降雨入渗条件下土质边坡浅层稳定性计算方法。对杭新景高速公路七里连接线工程沿线土质边坡稳定性进行分析,具体结论如下:可采用含水率分布参数A、修正系数λ、μ表征的反比例函数表示自然状态下土体的初始含水率分布规律。含水率分布参数对边坡稳定性影响表现为随着A值的增大,边坡初始稳定性逐渐下降,边坡受降雨影响的敏感程度也随之下降。降雨强度相同时,初始表面含水率越大引起边坡失稳所需的降雨时间越短;降雨时间相同时,初始表面含水率越大引起边坡失稳所需的降雨强度越小。在相同地下水位条件下,边坡降雨强度与导致边坡失稳所需的降雨时间成反比。

A rainfall infiltration test model which enables the measurement of the volumetric water content of soil is designed.The distribution and variation of the initial water content under rainfall infiltration are obtained through the test.Based on these results,a novel method for shallow stability analysis of earth slopes subject to rainfall infiltration is proposed by combining the unsaturated shear strength theory and the limit equilibrium method.The proposed method is then applied to study the stability of a soil slope along the Qili connecting line of Hang-Xin-Jing expressway.The main findings are as follows:the inverse proportion function characterized by water content distribution parameter A,correction coefficientλandμcan be used to describe the initial water content distribution of soil in natural state;with the increase of A value,the initial stability of the slope decreases,and the sensitivity of rainfall to slope instability also decreases;when the rainfall intensity is the same,the greater the initial surface water content is the shorter the rainfall time needed to cause the slope instability;and when rainfall time is the same,the greater the initial surface water content is the smaller the rainfall intensity needed to cause the slope instability.Under the same groundwater level,the rainfall intensity is inversely proportional to the rainfall time needed to cause the slope instability.