三峡库区某库岸滑坡地震动力响应机制分析

Analysis on mechanism of seismic dynamic response of a bank landslide in Three Gorges Reservoir Area

以三峡库区某库岸滑坡为模型,进行地震作用下的动态响应分析。综合运用Geo-Studio中Quake、Seep、Slope模块,分析库岸滑坡地震作用下的动态响应。结果表明:(1)滑坡在地震作用下,出现一个类似于"鞭梢效应"的现象,上部表层振幅大于下部,且上下部存在变形不同步,整体呈现出"S"型变形迹象;(2)滑坡整体呈现出不同程度的加速度放大作用,且放大的程度和坡体地形起伏及整体坡度有关;(3)库岸前缘首先发生液化现象,随着地震的持续,液化区沿着滑面向上蔓延,而中部表层极难发生液化,最后后缘也呈现出局部液化或者微弱液化的趋势;(4)考虑超孔隙水压力、地震惯性力及强度折减后的滑坡稳定系数远小于1,滑面处平均加速度大于某一临界值时会发生不可逆塑性变形。研究所得结果为水库滑坡治理提供参考。

By taking a bank landslide occurred in the area of Three Gorges Reservoir as the study model,the dynamic response under seismic effect is carried out herein. The dynamic response of the bank landslide under seismic effect is analyzed with the integrated application of the modules of Quake、Seep、Slope in Geo-Studio. The result shows that：（1） under seismic effect,the landslide presents a phenomenon similar to whipping effect; i. e. the surface amplitude of the upper part is larger than that of the lower part,while the deformations of both the upper and lower parts are not synchronized,thus it integrally shows an evidence of S shape deformation;（2） the landslide integrally presents the acceleration amplifying effect of different extents and the amplifying extent is just related to the topographic fluctuation of the landform and the integral slope gradient therein;（3） the liquefaction phenomenon firstly occurs at the front edge of the reservoir bank and then the liquefied zone upward extends along the sliding surface,but the liquefaction is quite hard to occur at the surface of the mid-part of the slope,while the evidence of local liquefaction or slight liquefaction also occurs at the rear edge at last;（4） under the consideration of that the landslide stability factor is to be far less than 1 after the reductions of the excess pore water pressure,seismic inertial force and strength,an irreversible plastic deformation is to be occur when the sliding surface average acceleration is greater than a certain critical value. On the whole,the study result can provide a reference for the control of reservoir landslide.