不同地层扰动工况下地铁隧道内力变化仿真模拟

Simulation of Internal Force Change in Subway Tunnel under Different Stratum Disturbance Conditions

地铁周边基坑开挖可能会引起隧道衬砌结构的内力变化,须进行可靠的安全评估。本研究依托某市地铁线地铁站附近的大型基坑开挖开展案例研究,采用MIDAS-GTS-NX软件对四种不同开挖阶段的工况进行有限元分析。结果表明,盾构隧道的弯矩、剪力及轴力在基坑开挖过程发生了变化,弯矩最大变化值3 kN.m/m,剪力最大变化值为2.5 kN/m,轴力最大变化值为20 kN/m,变化比率最大的内力剪力为4.3%。可以认为内力变化值处于较低水平,基坑开挖对盾构隧道内力状态影响较小。由于地铁结构的受力变化处于较低水平,可以认为深基坑施工不危及邻近地铁结构的安全。

The excavation of the foundation pit around the subway may cause the internal force changes of the tunnel lining structure,so a reliable safety assessment should be carried out.This study relies on a case study of large-scale foundation pit excavation near a metro Line 3 subway station in a city,and adopts MIDAS-GTS-NX software to conduct finite element analysis of four different excavation stages.The results show that the bending moment,shear force and axial force of shield tunnel change during foundation pit excavation.The maximum change value of bending moment is 3 kN.m/m,the maximum change value of shear force is 2.5 kN/m,the maximum change value of axial force is 20 kN/m,and the maximum change ratio of internal force shear is 4.3%.It can be considered that the internal force change value is at a low level,and the excavation of foundation pit has little influence on the internal force state of shield tunnel.Because the change of force of subway structure is at a low level,it can be considered that the construction of deep foundation pit does not endanger the safety of adjacent subway structure.