滑坡稳定性变化与地下水非稳定渗流初探——以三峡库区黄蜡石滑坡群石榴树包滑坡为例

STABILITY VARIATION OF A SLOPE ASSOCIATED WITH TRANSIENT GROUNDWATER FLOW∶A CASE STUDY ON SHILIUSHU- BAO LANDSLIDE IN HUANGLASHI LANDSLIDES, THREE GOR- GES PROJECT AREA,CHINA

把滑坡体离散化为一定数量的条块,基于水均衡原理建立了滑坡体地下水一维非稳定渗流的差分方程组,其中考虑了滑坡体地下水通过弱透水滑动带的越流排泄,对动态边界提出了处理方法。以三峡库区黄蜡石滑坡群的石榴树包滑坡为例,根据三峡水库蓄水前和蓄水后排泄区的不同水位条件,模拟了在强降雨过程中滑坡地下水的动态过程。结合考虑地下水渗透力的传递系数法,计算了石榴树包滑坡稳定性系数随时间的变化,结果表明无论是在三峡水库蓄水前还是蓄水后的极端降雨条件下石榴树包滑坡都是不安全的。在地下水非稳定渗流的影响下,滑坡稳定性对降雨和排泄区水位的响应具有滞后性。

By dividing the slope into slices, finite difference equations of one-dimensional transient unconfined groundwater flow in a slope are proposed on the basis of water equilibrium principle. Leakage of groundwater in the slope,through the weak permeable bottom slide-layer, is considered as well as the varying of seepage boundaries. The Shiliushubao landslide is studied as an example,which belongs to the Huanglashi landslides in the Three Gorges Project area, China. A strong rainfall with rising and dropping of river's or reservoir's water level, is designed to investigate the transient groundwater tables in this landside and the variation of its stability. The results show that the landside is not safe enough in the strong rainfall before or after the accomplishment of Three Gorges Project. As a result of unsteady flow of groundwater, the changes of the landslide's stability lag behind changes of rainfall rate and surface water level.