地下水条件下平行双隧道对场地地震反应影响的分析

Analysis of the Influence of Parallel Double Tunnels on Site Seismic Response under Groundwater Condition

通过有限元方法建立含有地下水及平行双隧道结构的场地模型,在模型底部输入水平地震波,分析场地表面在均匀土和层状土两种场地条件下的加速度变化规律。研究结果表明:隧道间距大小对地面的地震反应不是单纯的放大或缩小作用,而是影响地表加速度峰值的出现位置;地下水与地下结构的存在使地表不同位置呈现不同的反映情况,且层状土场地的放大效应比均匀土要大;双隧道对地震波的反射叠加作用,场地表面产生竖向加速度,其中隧道内侧的竖向加速度要大于隧道外侧,隧道外侧的竖向加速度要大于隧道上方的竖向加速度。

The site model with groundwater and parallel double tunnel structures was established by finite element method. Horizontal seismic waves were input into the bottom of the model to analyze the acceleration changes of the ground surface under two types of site conditions: homogeneous soil and layered soil. The results show that different distances between the two tunnels do not simply magnify or reduce the ground seismic response,but affects the location of the peak acceleration of the ground surface;Because of the existence of groundwater and underground structure,the different locations of the surface show different responses,and the amplification effect of layered soil site is greater than that of homogeneous soil;Due to the reflection and superposition of seismic waves by double tunnels,vertical acceleration is generated on the surface of the tunnel;The vertical acceleration inside the tunnel is greater than that outside the tunnel,and the vertical acceleration outside the tunnel is greater than that above the tunnel.