三峡库区白家包滑坡频发微震下动力响应机制分析

Research on Dynamic Mechanism Response of Baijiabao Landslide in Three Gorges Reservoir under Frequent Microseisms

三峡库区微震级低烈度地震频发,但相关研究较少,因此以三峡库区白家包滑坡为研究对象,耦合运用Geo-Studio中Quake、Seep、Slope模块模拟分析该滑坡频发微震下的动力响应情况。结果表明,由于能量传输耗能,后缘记录点位移小于前缘,且由于表层放大效应,上部记录点位移大于下部;滑坡整体呈现出不同程度的加速度放大作用,且前缘整体放大倍数大于后缘,表层大于内部,与动态位移分析一致;滑坡仅175m水位附近发生微弱液化,随着地震的持续,液化区沿滑体表面向下蔓延扩大,其他位置滑面无液化迹象,因此考虑不同因素的两种Quake应力法稳定系数时程曲线完全一致,且当滑面平均加速度大于临界值时,稳定系数小于1,由于地震持时较短,不会整体失稳,仅发生不可逆累进塑性变形。

The low magnitude and intensity earthquake occurs frequently in the Three Gorges Reservoir Area,but there are few studies on frequent microseisms.Therefore,taking Baijiabao landslide as research object,the dynamic response of frequent microseisms was analyzed by using Quake,Seep and Slope modules in GEO-Studio.The results show that the displacement of trailing edge recording point is smaller than the leading edge due to the energy loss in transmission,the displacement of the upper recording point is larger than the lower portion due to the surface magnification effect;the landslide as a whole exhibits different degrees of acceleration magnification,the overall magnification of the leading edge is greater than the trailing edge,and the surface is larger than the inner,it is consistent with the dynamic displacement analysis;the landslide shows only weakly liquefied around 175 m water level;as the earthquake continues,the liquefaction zone spreads down along the surface of the landslide,but other locations of slip surface has no signs of liquefaction.So,the stability curves of the two Quake stress methods considering different factors are identical.When the mean acceleration of the slip surface is greater than the critical value,the stability coefficient is less than 1;due to the short duration of the earthquake,the whole will not be instability,only it appears irreversible progressive plastic deformation.