类矩形盾构下穿施工引起邻近隧道变形研究

Deformation of Adjacent Tunnel Caused by Underpass Construction of Quasi-rectangular Shield Tunnel

基于镜像法和Mindlin解,考虑土体损失、刀盘推力、盾壳摩擦力和注浆压力的影响,推导出类矩形盾构隧道施工在既有隧道轴线处产生的附加应力计算公式,将既有隧道简化为由剪切弹簧连接的弹性地基短梁,结合最小势能原理推导出既有隧道竖向位移计算公式。依据工程实例构建数值计算模型,对比本文计算结果和数值模拟结果,验证本文计算方法的适用性。研究结果表明:本文计算方法的结果与数值模拟结果吻合程度高,验证了本文计算方法的正确性;随着类矩形盾构隧道掘进,邻近隧道的纵向位移、环间剪切量和剪切力不断增大,在盾构机通过邻近隧道轴线20 m后趋于稳定;邻近隧道沉降变形最大处的环间剪切量和剪切力最小,沉降变形曲线反弯点处的环间剪切量和剪切力最大。

Based on the mirror method and the Mindlin solution,considering the influence of soil loss,cutterhead thrust,shield shell friction and grouting pressure,the calculation formula of additional stress generated by the construction of quasi-rectangular shield tunnel at the axis of adjacent tunnel was derived.The adjacent tunnel was simplified as a short beam on elastic foundation connected by shear springs,and the formula for calculating the vertical displacement of the adjacent tunnel was derived by combining the principle of minimum potential energy.The numerical calculation model was built according to the engineering example,and the calculation results in this paper and numerical simulation results were compared to verify the applicability of the calculation method in this paper.The research results show that the results of the calculation method in this paper are in good agreement with the numerical simulation results,which verifies the correctness of the calculation method in this paper.The longitudinal displacement,inter-ring shear amount and inter-ring shear force of adjacent tunnel increase gradually with the tunneling of the quasi-rectangular shield tunnel,and tend to be stable after the shield machine passes through the existing tunnel axis for 20 m.The inter-ring shear amount and the inter-ring shear force are the smallest at the point where the settlement deformation of the adjacent tunnel is the largest.The inter-ring shear amount and the inter-ring shear force are the largest at the inverse bending point of the settlement deformation curve.