地震作用下层状岩质边坡动力响应

层状岩质边坡是川藏铁路沿线区域常见的地质体,边坡的地震稳定性对工程建设具有重要的影响.采用有限差分法软件FLAC3D建立顺层边坡及反倾边坡的数值模型,通过对比分析两种典型层状边坡的动力加速度响应,研究地震作用下层状边坡的动力响应特征及变形机理.研究结果表明:软弱夹层对层状边坡的波传播特征具有影响,使地震波在坡内传播过程中出现局部的放大效应;高程及软弱夹层对层状边坡的动力响应具有放大效应,相同高程条件下坡表的放大效应大于坡内;与反倾边坡相比,顺层边坡的放大效应随高程增加表现出强烈的非线性增加趋势;层状边坡的动力放大效应随地震动幅值的增加而增加,水平地震力作用下层状边坡的动力放大效应大于垂直地震力作用下层状边坡的动力放大效应;软弱夹层对层状边坡的动力变形特征具有控制性作用,最上层软弱夹层为潜在滑移面.

Dynamic Response of Layered Rock Slopes under Earthquakes

Layered rock slope is a common geological body along the Sichuan-Tibet Railway. The seismic stability of slopes has an important effect on engineering construction. Numerical models of bedded and toppling slopes were established by using finite difference method software FLAC3D. By comparing and analyzing the dynamic acceleration response of two typical layered slopes, their dynamic response characteristics and deformation mechanism under earthquakes are studied. The results show that weak interlayer has an effect on the wave propagation characteristics in layered slopes, which results in a local amplification effect during the process of seismic wave propagation in the slopes. The dynamic response of the layered slope is amplified by the elevation and weak interlayer, and the amplification effect of the slope surface was greater than that of the internal slope under the same elevation condition. Compared with the toppling slope, the amplification effect of bedded slope shows a strong nonlinear increase trend with the increase of elevation. The dynamic amplification effect of the layered slopes increases with the increase of ground motion amplitude, and their dynamic amplification effect under horizontal seismic force is greater than that of the vertical seismic force. The weak interlayer controls the dynamic deformation characteristics of layered slopes, and the topmost weak interlayer is the potential sliding surface.