浅埋暗挖地铁车站地表沉降及既有线变形分析

浅埋暗挖地铁车站穿越既有地铁隧道施工地表沉降及既有线的变形的控制对施工及运营安全具有重要意义。以北京地铁4号线西单站下穿长安街，上跨地铁既有1号线开挖过程为例，在详细研究该区工程地质条件和地铁设计参数的基础上，采用FLAC^3D工程分析软件对地铁开挖过程及其引发的地表、拱顶及既有隧道的变形规律进行了数值模拟分析，优化开挖施工方案，模拟动态施工过程，合理设计隧道开挖步序，并对施工中的监控量测提出建议．指导地铁安全施工。

On the Ground Surface Settlement and Existing Line Deformation Caused by the Shallow-burying and Undercutting Construction of Subway Station

For the shallow-buried undercutting subway station crossing the existing subway tunnel, control on the ground surface settlement and deformation of existing line is of significance to the construction and operation safety. Using the excavation process of Beijing Metro 4# Xidan Station under crossing Chang＇an Street, and over crossing the existing 1# Line as an example, based on detailed study on this area＇s geological conditions and subway design parameters, this paper uses FLAC3D Engineering Analysis Software to make numerical simulation on the tunnel excavation process and the deformation rules of the ground surface, vault, as well as the existing tunnel. Therefore, the excavation construction scheme is optimized, the dynamic construction process is simulated, and the procedure of tunnel excavation is rationally designed. Also, suggestions are made on the monitoring and measurement of the construction, which can guide the safe construction of the subway.