高压富水砂层超大直径盾构隧道下穿既有地铁影响分析和控制措施

Influence Analysis and Control Measures of Super-large Diameter Shield Tunnel Under High Pressure and Water-rich Sand Stratum Underpass Existing Subway

针对超大直径盾构隧道下穿既有地铁线路时引起的地表沉降及既有地铁沉降问题,以北京市东六环拟建隧道下穿既有北京地铁6号线为工程背景,利用有限元软件模拟盾构施工过程获得不同控制位置的变形及应力数据。结果表明:拟建盾构隧道下穿地铁6号线施工过程中,地表沉降及6号线衬砌结构沉降均在变形控制标准内且影响不大,安全风险可控;拟建盾构隧道通过设置试验段、加强中盾注浆、控制掘进姿态、加强监测、做好地铁轨道防护等措施,可大幅降低相关施工风险。

In order to study the surface settlement and the settlement of the existing subway caused by the super-large diameter shield tunnel underpass the existing subway,this paper takes the proposed tunnel of Beijing East Sixth Ring Road underpass the existing Beijing Subway Line 6 as the engineering background. The deformation and stress data at different control positions were obtained by simulating shield construction process with use of the finite element software.The results show the surface settlement and the settlement of the Line 6 lining structure are both within the deformation control standard,and the impact is not large,and the risk is controllable during the construction of the proposed shield tunnel underpass subway Line 6. The proposed shield tunnel can greatly reduce the related construction risks by setting up test sections,strengthening the middle shield grouting,controlling the driving posture,strengthening monitoring,and doing a good job in the protection of the subway track.