曲线盾构隧道施工期地表位移计算方法及影响因素分析

Calculation method and influencing factors of surface displacement during construction of curved shield tunnel

为了分析曲线盾构隧道施工期地表位移变化规律及影响因素,建立了考虑盾构主动铰接机构的曲线隧道开挖力学模型,分别提出了盾构施工附加应力和地层损失所引起的地表位移计算方法。基于实际工程,开展了相应监测试验和数值模拟,研究了影响地表位移偏移的敏感度指标。结果表明:曲线段地表位移沿隧道开挖方向向隧道内侧偏移,计算方法所得曲线段地表最大位移值和偏移值与实测值基本一致;敏感度分析发现,不平衡系数的敏感度最高,而在曲线超挖间隙因素中转弯半径和开挖半径敏感较高。建议曲线段施工应合理控制内外侧油缸推力差和超挖范围。

To analyze the variation law and influencing factors of surface displacement during the construction of curved shield tunnel.The mechanical model of curved shield tunnel excavation considering active articulated mechanism is established,and the calculation methods of surface displacement caused by additional stress and ground loss based on mirror method and orifice expansion theory are deduced respectively.Based on the actual project,the corresponding monitoring test and numerical simulation are carried out,the sensitivity index affecting the surface displacement offset of curved shield was researched.The results show that:The surface displacement of the curved section is offset to the inside of the tunnel in the direction of tunnel excavation,and the maximum displacement value and offset value of the curved section obtained by the calculation method are basically consistent with the measured values.It is found that the sensitivity of the imbalance coefficient is the highest,while the turning radius and excavation radius are sensitive in the curve over-digging gap factor.It is recommended that the thrust difference and overexcavation range of the inner and outer cylinders should be reasonably controlled in the construction of the curve section.