降雨和蒸发对土质边坡稳定性的影响

Effects of rainfall infiltration and evaporation on soil slope stability

降雨入渗降低边坡的稳定性,蒸发增加边坡的稳定性,降雨和蒸发对边坡稳定性的定量研究是很有意义的。采用蒸发和降雨模型对边坡进行非饱和-非稳定渗流分析,用总凝聚力表示的Bishop极限平衡法计算边坡安全系数。采用数值方法对算例土质边坡进行了研究,得到了孔隙水压力随时间变化的关系、边坡安全系数随时间变化的关系。结果显示:土体中孔隙水压力与天气条件、边坡安全系数与天气条件之间存在滞后关系;降雨和蒸发对边坡的表层滑动稳定性影响非常大,对深层滑动稳定性影响相对较小;降雨过程中边坡的临界滑动面由较深位置向较浅位置转变,蒸发过程则相反。

It is advantageous to know how much rainwater decreases or .evaporation increases the stability of a soil slope. Numerical model was used to quantify the effect of rainwater and evaporation on the stability of a case slope. With raining model and evaporation model, unsaturated-unsteady seepage analysis was used to calculate pore pressure of the case slope, and Bishop Equilibrium balance method with total cohesion was used to calculate the stability factor of the case slope. Relationships between the pore pressure and time, between the safety of stability and time were obtained. Results show that changes in slope stability and pore pressure lag behind the change of weather; infiltration and evaporation affect the stability of shallow slip surface greatly, the stability of deep slip surface relatively little; in the process of rain, the critical slip surface changes from deep surface to relative shallow surface, in the process of evaporation, the situation is opposite.