地铁双线盾构隧道施工过程中地表沉降模拟分析

Simulation Analysis of Surface Settlement during the Construction of Two-Lane Shield Tunnel of Metro Line

城市地下隧道复杂多变的地层条件、极度敏感的城市基础设施环境,使得城市地下隧道盾构施工过程中面临极大的安全风险。为确保盾构机通过海陆交互相沉积区的施工安全及盾构隧道施工后的安全运行,本文以天津地铁11号线三经路站~六经路站双线隧道盾构区间施工为背景,采用MIDAS-GTS软件对不同施工错距、不同埋深下的地层位移、地表竖向沉降进行对比分析。结果表明:当错距开挖长度大于4.5倍隧道直径时,地表最终沉降值变化较缓,现场施工可在此范围外进行施工;整体地表横向沉降曲线呈现出“窄而深”的形态,施工中要根据沉降变化注意隧道盾构施工时的埋深。

The complex and changeable stratigraphic conditions of urban underground tunnels and the extremely sensitive urban infrastructure environment make the shield construction process of urban underground tunnels face great safety risks.In order to ensure the construction safety of the shield machine through the intersection of land and sea deposition area and the safe operation of the shield tunnel after construction,this paper takes the construction of the shield interval of the two-lane tunnel of Tianjin Metro Line 11 from Sanjing Road Station to Liujing Road Station as the example,and uses the MIDAS-GTS software to comparatively analyze the stratum displacement and the vertical settlement of the ground surface under different construction staggered spacing and different depths of burial.The results show that when the staggered excavation length is more than 4.5 times the diameter of the tunnel,the change of the final settlement value of the ground surface is slower,and the on-site construction can be carried out outside of this range;the overall lateral settlement curve of the ground surface shows a narrower and deeper pattern,so the construction should pay attention to the depth of the tunnel shield according to the change of the settlement.