库水位骤降时的滑坡稳定性评价方法研究

Research on method of landslide stability valuation during sudden drawdown of reservoir level

三峡水库蓄水及水位波动,将极大地改变滑坡体内的水文地质条件,库水位骤降和暴雨入渗是导致滑坡的主要因素。库水位骤降时的滑坡稳定性评价是滑坡防治中的一个难题。根据三峡水库水位调控方案和库区滑坡地下水作用的力学模式,利用有限元模拟库水位从175 m骤降至145 m时的滑坡暂态渗流场。建立了渗透力作用下滑坡稳定性评价的不平衡推力法。研究表明:滑坡的渗透系数和库水位下降速度是影响滑坡稳定性的主要因素,当库区堆积层滑坡渗透系数小于0.864 m/d,库水位发生骤降为2 m/d。库水位骤降时滑坡稳定性降到最小的水位通常在175 m水位以下10～20 m处。其研究为库区175 m水位滑坡治理提供了科学依据。

When the Three Geoges Reservoir impounding water and water; level fluctuating, the hydrological condition of landslides will be greatly changed. Both the sudden drawdown of reservoir water level and rainstorm infiltration become major factors that effect on the stability of landslide. The stability evaluation of landslide is difficult in the sudden drawdown of reservoir water level. On the basis of the project that reservoir water level is controlled and the mechanical mode that the ground water acts on landslides in Three-Gorges Reservoir area, transient seepage due to the sudden drawdown of reservoir water level from 175 m to145 m is computed using the finite element. Disequilibrium push method is applied to stability evaluation of landslide under seepage forces. The results of the stability analysis show that permeability coefficient of landslides and the descending velocity of reservoir water level are main factors that effect on the stability of landslide When the permeability coefficient of landslides is less than 0.864 m/d and velocity is 2 m/d, the sudden drawdown of reservoir water level will take place. And water level on which safety factor of Landslide is minimum drops by 10m to 20m under 175m water level, which will provide scientific bases for the treatment of landslide in 175m water level in Three Gorges Reservoir.