软硬不均地层盾构近接下穿施工掘进参数优化分析

盾构法修建城市地铁时，盾构掘进参数对于控制地表沉降、保证施工安全等具有重要影响。以深圳地铁7号线盾构隧道下穿既有2号线为工程背景，针对在软硬不均地层情况下盾构隧道下穿既有隧道及过街通道，运用ABAQUS建立三维计算模型，对盾构施工进行全过程模拟及掘进参数优化分析。研究结果表明:①土仓压力及注浆压力对过街通道沉降相对于地表影响较大，施工过程中应当注意对过街通道底部进行监测；②对于软硬不均地层盾构下穿既有隧道及过街通道采用0.30~0.40 MPa土仓压力以及采用0.25~0.30 MPa注浆压力施工较为合理

Excavation Parameters Optimization Analysis of Approaching Construction with Shield Method in Uneven Stratum

During construction of urban metro in the shield method, the excavation parameters are essential for controlling ground settlement and securing construction safety. Using the background of constructing Shenzhen Metro Line 7 in shield method below existed line 2, a three-dimensional calculation model is established by ABAQUS for the shield tunnel below the existing tunnel and underpass in uneven stratum to simulate whole shield construction process, and perform optimized analysis of the excavation parameters. The results indicate that, ①soil warehouse pressure and grouting pressure has higher impact on the underpass settlement than the surface, and during the construction, it is noted that the underpass bottom is monitored; and ② it is more reasonable that 0.30~0.40 MPa soil warehouse pressure and 0.25~0.30 MPa grouting pressure is used to construct the tunnel below the existing tunnel and the underpass in the shield method in uneven stratum.