露天矿边坡饱和渗透系数随机场数值模型研究

Numerical model for open-pit mine slope considering stochastic field of saturation permeability

为分析强降雨入渗及渗透系数空间变异性对闭坑露天矿边坡渗流场的影响程度,基于非饱和渗流理论和随机场理论,采用非侵入式随机方法,通过FISH语言编写非饱和区单元饱和度、渗透系数与基质吸力的修正函数,建立饱和G非饱和渗流随机场模型,开展强降雨作用的高大陡深岩质边坡渗流特征研究.研究结果表明,修正饱和G非饱和渗流随机场模型能够准确地描述露天矿边坡的降雨入渗过程.且降雨入渗主要影响到露天矿边坡浅层渗流场.随降雨持时变化,在坡面与地下水位线之间形成包围的且逐渐缩小的非饱和区.坡面最早出现暂态饱和区且厚度逐渐增加,但增幅逐渐放缓.同时坡面点孔隙水压力最早达到稳定值零,离坡面越远的点孔隙水压力达到稳定值零的用时会越长.该结论可为闭坑露天矿边坡的地质灾害风险预测提供参考意义.

It is widely known that the spatial variability of the mechanical properties of rock mass exists and that rainfall induces a decrease in matric suction which in turn affects the process of infiltration into an unsaturated slope.Therefore,it is necessary to analyze the effects of the rainfall infiltration and the spatial variability of permeability on the seepage field and the factor of safety of a slope.This paper intends to explore the nonlinear flow characteristics of a high and steep rock slope.Based on the unsaturated seepage theory and the stochastic field theory,rectified functions that take into account saturation,permeability and matric suction for unsaturated slope were programmed by using fish,a saturated-unsaturated stochastic seepage field model established by using the non-intrusive stochastic method.The results show that the modified saturated-unsaturated seepage stochastic field model can accurately describe the behavior of an open-pit mine slope suffering from rainfall infiltration.Rainfall infiltration mainly affects the shallow seepage field of the rock slope.With the change of duration of rainfall,an enclosed and gradually shrinking unsaturated zone is formed between the slope surface and the groundwater level.The transient saturated zone appears at the surface of slope earliest and its thickness increases gradually,but the increase slows down gradually.At the same time,the pore water pressure at the surface of slope reaches the value of zero at the earliest time,and it takes a long time for the point far away from the surface of slope to reach the value of zero.The conclusion can provide a reference value for the prediction of the geological disaster of an open-pit slope.