地铁盾构区间近距离下穿顶管隧道力学响应及沉降控制标准研究

Study on the Mechanical Effects and Deformation Control Standards for Shield Tunnel Undercrossing the Existing Pipe-Jacking Tunnel

为解决郑州地铁4号线盾构区间隧道近距离下穿既有交通工程顶管群隧道变形控制问题,采用数值分析和现场监测的手段,揭示了地铁盾构隧道下穿施工对既有顶管群隧道结构变形的影响规律,建立以数值模拟为基础、以隧道管节接缝允许张开量和结构线形允许最小附加曲率半径为控制目标的既有顶管隧道沉降控制标准,并通过现场监测印证了数值计算结果的正确性和沉降控制标准制定方法的可行性。研究表明:(1)盾构以37°交角斜穿施工时,上部顶管隧道纵向沉降曲线呈现非对称特征,且施工过程中结构沉降曲线出现了一定的平移和偏转现象;(2)相对于接缝张开量控制标准,基于顶管隧道允许附加曲率的沉降控制要求相对更为严格,建议下穿施工扰动下顶管隧道最大允许沉降值取27 mm。

To solve the deformation control problems caused by underpass construction of tunnel,the project of shield tunneling of Zhengzhou Metro Line 4,undercrossing closely the existing traffic pipejacking tunnels,is studied.Numerical simulation combined with field monitoring is used to reveal the deformation law of the existing jacking tunnels during shield tunnel construction.Based on numerical simulation results,settlement control standard of the pipe-jacking tunnel,the allowable joint opening value of pipe-jacking joints and the minimum allowable radius of curvature of the structural line are established.Then the correctness of the numerical calculation results and the feasibility of setting method of the settlement control standard are confirmed by on-site monitoring.The main conclusions are as follows:(1)During the process of the two shield tunnels crossing the pipe-jacking tunnels at an intersection angle of 37°,the vertical settlement curves of the upper pipe-jacking tunnels present asymmetric characteristics,and the settlement curves of the tunnels show some translation and deflection.(2)Compared with the joint opening control standard,the settlement control requirements based on allowable additional curvature of pipe jacking tunnel deformation are relatively stricter.It is suggested that the maximum allowable settlement value of the jacking tunnel under construction disturbance should be 27mm.