地铁隧道暗挖施工对地表密集建筑物的影响研究

Infl uence on concentrated buildings induced by undercutting construction of subway tunnel

在城市地铁修建过程中,地铁下穿已有管线、地面建筑物往往是整个线路修建过程中的难点及风险控制点。本文基于深圳市地铁5号线某暗挖隧道区间,针对暗挖隧道施工对地表密集民房的影响开展研究。隧道开挖采用上下短台阶加临时仰拱和中立柱施工法。采用有限元分析方法对两种不同工况进行数值仿真计算,研究最优开挖策略。研究表明:相对于未处理工况,采用旋喷桩隔离墙对隧道附近土层进行处理,以及对隧道正上方房屋进行拆除后,地表沉降减小幅值达49%,隧道拱顶沉降减小幅值达35%,临近建筑的沉降及差异沉降减小幅值达67%,同时可以有效减少施工开挖对地面沉降的影响。

During the urban subway construction, the stages when the tunnel pass under existing pipelines and buildings are always the technology and risk control points. Base on the underground excavated tunnel section of Shen-Zhen subway line5, study was conducted on the influence of concentrated buildings above the excavated tunnels. Tunnel excavation method adopted the up-down-short-terrace method, with temporary Invert and B-pillar. Two calculation conditions are computed by finite element analytical method to determine the optimal excavation strategy. compared to the original condition, the updated calculation condition took Jet grouting pile isolation wall to strengthen soil close to the tunnel structure and dismantled the buildings above the tunnel. The results showed that by the updated calculation condition, the amplitude of ground settlement decrease 49% than the original condition, while the amplitude of settlement on tunnel vault decrease 35%, and amplitude of settlement and differential settlement of adjacent building decrease 67%. Therefore, the treat measure were proved effectively on reduceing the influence of ground settlement by excavate construction.