库水位下降条件下堆积层滑坡稳定性分析

Stability of colluvial landslide with drawdown of reservoir water level

为研究库水下降过程中不同因素作用下的堆积层滑坡稳定性响应规律,基于块体极限平衡理论用解析法分析地下水浸润线下降时,影响滑坡稳定性变化的主要因素。概化典型堆积层滑坡地质模型,采用数值模拟手段获取在各因素变化时,库水下降条件下不同时刻滑坡稳定系数,统计分析其变化规律。研究发现,库水下降时,滑坡稳定性变化受滑体渗透系数K、地下水浸润线变动区内的下滑带倾角α和阻滑段与下滑段体积比ε、滑带内摩擦角φ等影响,表现出逐步下降型、逐步上升型、"U"字型、阶梯上升型四类变化规律;K、ε控制稳定系数大小及其曲线形态,α和φ仅影响稳定系数值和不同时刻的稳定系数差异;库水下降始末滑坡的稳定系数变化百分比Q与渗透系数负对数-lnk在逐渐下降型曲线中表现出较好的幂函数关系,ε、α对幂函数的系数和指数的影响呈现出较好的规律性。

In order to study systematically landslide stability response law influenced by different factors in the process of water drop,based on limit equilibrium theory,the main factors when groundwater invasion line declines were analyzed by analytic method. Then,typical colluvial landslide geological model was generalized and numerical simulation was used to obtain different moment stability coefficient of landslide under the condition of reservoir water dropping. Change laws of landslide stability with different factors were analyzed.The results show that when the reservoir water level falls,the change of landslide stability is observably influenced by permeability coefficient K of sliding mass、internal friction angle φof sliding zone as well as dip angle αof slip plane and the ratio ε of stopping slide sect to main sliding sect in the changing area of groundwater infiltration line. The regularity of stability variation shows four types including gradual decline,gradual ascent,U-shaped,stair-step ascent. The permeability coefficient K and the ratio ε of stopping slide sect to main sliding sect control the figure and changing shape of stability coefficients. The dip angle αand internal friction angle φof sliding zone only affect stability coefficient value and difference between different times. In gradually decline type, power function relationship lies in negative logarithm of permeability coefficient,that is-lnk,and the difference percentage Q between stability coefficient of ending andbeginning reservoir water. The coefficient and exponent of power function present a good regularity with the changing of the ratio ε of stopping slide sect to main sliding sect and dip angle αof slip plane.