地铁车站长距离密贴下穿既有隧道结构的地震响应

为研究长距离密贴下穿地下空间结构的地震响应特征,以某新建地铁车站结构长距离密贴下穿既有隧道结构为对象,基于FLAC3D有限差分软件,建立三维数值计算模型。在输入日本阪神(Kobe)地震波的条件下,分析上部既有隧道结构在有无下穿地铁车站结构时的地震响应。计算结果表明:输入水平方向的地震波,有无地铁车站结构的隧道结构的位移-时程与加速度-时程曲线规律大致相同,均随深度的增加而减小,且变化趋势相似于施加的地震波。隧道顶板与底板的加速度反应时程曲线与基岩输入地震波的形态基本相近,隧道结构顶板的水平加速度峰值大于底板的水平加速度峰值。与单一隧道结构的位移-时程和加速度-时程曲线相比,密贴地铁车站结构对隧道结构的动力响应有减弱效果。下穿地铁车站对上部隧道结构的动力加速度响应有不同程度的减弱效应,且越靠近车站结构减弱幅度越大,下部车站结构的减震耗能现象存在于某一局部范围内。

Analysis on seismic response of long-distance and closely-attached subway station to existing tunnel structure

This paper introduces a model of tunnel structures designed specifically to investigate the seismic response characteristics of the long-distance and closely-attached underground space. This model follows from a targeted analysis of what occurs with a newly-built subway station structure and the upper tight stick of an existing tunnel structure using finite difference software FLAC3D. The paper goes further by analyzing the seismic response of the tunnel with or without a subway station passing through a tunnel, as is conditioned by inputting Kobe earthquake waves. The calculation shows that inputting the horizontal direction earthquake waves yields roughly the same law underlying curves of relationship between dis- placement time history and acceleration time history related to a tunnel structure with or without Metro stations, as is illustrated by the curves which tend to decrease with an increasing depth and show a chan- ging trend similar to the earthquake waves applied; the roof slab and bottom slab of a tunnel have a hori- zontal acceleration with time-history curves basically similar to the seismic wave of the bedrock, and the roof slab of a tunnel structure produces a horizontal acceleration with a peak greater than that of the bot- tom slab; compared with the curve between the displacement time history and acceleration time history of a single tunnel structure, a closely-attached subway station structure exerts a weakening effect on the dy- namic response of the tunnel structures ; and a subway station passing through the tunnel has a weakening effect of varying degrees on dynamic acceleration response of the upper structure tunnel and yields an in- creasingly greater reduction, the closer it is to a station structure, suggesting the occurrence of damping energy dissipation, as in the case of lower part of the station structure.