城市地铁隧道施工对古建筑沉降的影响研究

采用大型有限元软件ABAQUS模拟城市地铁隧道盾构开挖诱发地表沉降规律,并针对开挖推进距离、开挖面支护以及地表建筑物刚度条件对古建筑物地表沉降影响进行了详细分析,得到以下结论:拱顶沉降、上测点周边收敛位移和下测点周边收敛位移,实测数据分别比数值模拟数据大5.41%、13.21%和10.15%,这与现场施工条件比数值模拟更为复杂有关,也说明数值模拟比较可靠。增大盾构推进距离会加大古建筑物地表最大沉降值,但是增大幅度有限,当推进距离增大为原来的3倍时,古建筑物地表最大沉降增大幅度低于10%;增大盾构开挖面支护力会明显减小古建筑物地表最大沉降值,施工过程中可以适当采取增大开挖面支护力的方法来减小古建筑物地表沉降。盾构上方地表存在古建筑物能明显减小地表最大沉降值,但地表沉降槽宽度也相应增加,因此施工过程中若盾构上方存在古建筑物,应进行特殊考虑。

Study on Numerical Simulation of Ground Settlement Induced by Shield Tunnel Construction

The large-scale finite element software ABAQUS software was used to simulate the ground settlement law induced by shield tunneling in urban subway tunnels.The effects of excavation propulsion distance,excavation surface support and surface building stiffness conditions on the surface settlement of ancient buildings were analyzed in detail.The conclusions are as follows:the settlement of the vault,the convergence displacement around the upper measuring point and the convergence displacement around the lower measuring point,the measured data are 5.41%,13.21%and 10.15%larger than the numerical simulation data respectively,which is more complicated than the numerical simulation of the field construction conditions.Related,it also shows that the numerical simulation is more reliable.Increasing the shield propulsion distance will increase the maximum settlement value of the ancient buildings,but the increase is limited.When the propulsion distance is increased by 3 times,the maximum settlement of the ancient buildings is less than 10%.The large shield tunneling surface support force will significantly reduce the maximum settlement value of ancient buildings.During the construction process,the method of increasing the retaining surface support force can be appropriately adopted to reduce the surface settlement of ancient buildings.The existence of ancient buildings on the surface above the shield can significantly reduce the maximum settlement value of the surface,but the width of the surface settlement trough also increases accordingly.Therefore,if there are ancient buildings above the shield during construction,special consideration should be given.