新建地铁线路下穿既有车站的仿真模拟分析

以青岛某即将修建的线路下穿既有车站为例,利用有限元软件对地铁结构进行数值模拟分析,研究在硬岩地区,新建线路采用型钢格栅密贴下穿及采用CRD法近距离下穿2种方案引起的既有站底板位移变化的规律。主要结论如下:1)为了避免应力集中,下穿线路应尽量避免布置在既有线中柱下方。2)随着2条线路轨面标高距离的增加,开挖引起的既有线底板沉降及最大、最小主应力逐渐减小,当2条线路之间的净距达到3 m左右时,引起的底板沉降仅0.9 m左右,为密贴下穿的14.5%;最大、最小主应力为密贴下穿的75%左右。3)施工时应加强监控量测,必要时进行换撑施工线路二次衬砌。

Numerical Simulation for New Metro Tunnel Passing Underneath Existing Metro Station

A new Metro tunnel is planned to pass underneath an existing Metro station. In the paper, the Metro structures are simulated by means of finite element software. Two cases, i.e., Case 1 “double rectangular tunnels passing closely underneath existing Metro station” and Case 2 “double horseshoe shaped tunnels passing underneath adjoining existing Metro station”, are studied. Conclusions drawn are as follows: 1) The new tunnel should be located as far away from the central columns of the existing Metro station as possible, so as to avoid stress concentration; 2) As the distance between the elevations of the tracks of the two Metro lines increases, the settlement and the maximum and minimum principal stresses of the floor of the existing Metro station induced by the excavation of the tunnels below reduce gradually. When the clear distance between the two Metro lines is 3 m, the settlement of the floor of the existing Metro station induced by the excavation of the tunnels below is only 0.9 m, which is 14.5% of that in Case 1; and the maximum and minimum principal stresses induced are 75% of those in Case 1; 3) Monitoring shall be strengthened during construction, and if necessary, support replacement shall be made to facilitate secondary lining construction.