地铁区间隧道穿越可液化土层的地震响应特性

Seismic response characteristics behind subway interval tunnels traversing liquefiable soil

为研究可液化地层中地下结构的地震响应规律,基于有限差分软件FLAC3D计算平台,建立可液化地层中地铁区间隧道结构的数值模型,分析其在地震作用下的动力反应以及内力的时程分析法与反应位移法计算结果。结果表明,可液化地层中地铁区间隧道结构的地震位移反应具有明显的滞后性,竖向位移达到峰值的时刻滞后于水平位移达到峰值的时刻。隧道结构受力最危险的部位为拱腰及拱顶,与结构发生最大变形的部位吻合。以受弯构件为主的地下结构内力可以采用反应位移法近似计算,以受压构件或压弯构件为主的地下结构内力,宜采用时程分析法计算。该研究可为地铁地下结构的抗震设计提供参考。

This paper attempts to investigate the law^ underlying the seismic response of underground structures in the liquefiable stratum. The study consists of building a numerical analysis model for the subway interval tunnel structure in the liquefiable stratum using the finite difference software FLAC3D computing platform; analyzing the seismic responses under the action of earthquakes; and analyzing the internal force computation derved from time histor analysis and displacement response method. The results show that there is an obvious hysteresis in the seismic displacement response tunnel strjicture in the liquefiable stratum, and the horzontal displacement lags behind the vertical dispacement in tems of the rate at which the peak value is reached; the most in the tunnel structure under stress are obsered in arch and vault and this coincides with the location where strjicture is subjected to the maximum deformation ; and the internal force dominated by bending strjictural member could be calculated by employing response displacement method while intenal forces of underground strjictures dominated by compression members or compression bending members could be calculated preferably by applying time histor analysis method. The study could provide a reference for seismic design of underground subway strctures.