软土地层大直径泥水盾构掘进引起的地面变形分析

Ground settlement caused by large-diameter slurry shield during tunnel construction in soft soils

为了研究大直径泥水平衡盾构施工引起的地层变形,基于Mindlin解,推导了在泥浆重度影响下开挖面不均匀附加压力、不均匀分布下盾壳摩擦力、环向消散下盾尾注浆压力引起的地层变形,叠加地层损失引起的地层变形,获得了大直径泥水平衡盾构施工引起地层变形的计算公式,典型工程实例结果表明:①不考虑泥浆重度、不均匀分布和环向消散等因素会高估地面纵向位移的隆起值而低估沉降值,本文计算方法所得地面纵向位移与实测值吻合较好;②本文方法计算所得的大直径泥水平衡盾构施工引起的地面横向位移与实测变形基本吻合,且符合高斯曲线正态分布。研究成果可为控制和预测大直径盾构隧道施工引起的地层位移提供理论指导。

To study the ground settlement caused by large-diameter slurry shield during tunnel construction in soft soils,the formulas are proposed on the basis of the Mindlin solutions.The effects of unit weight of slurry on the additional pressure around cutting head,the effects of shield gravity on the non-uniform distribution of softening skin frictions along the shield,the dissipation of grouting pressure along the lining rings and the ground deformation caused by volume loss ratio are considered in the proposed solutions.The calculated and field results are compared through a typical engineering case.The results show that:(1)Without considering the unit weight of slurry,non-uniform distribution and circumferential dissipation,the heave of ground longitudinal displacement is overestimated,and the settlement value is underestimated.The calculated results of longitudinal deformation by the proposed method are in good agreement with the measured results.(2)The calculated results of transverse deformation by the proposed method are in good agreement with the measured results.The transverse deformation of ground surface induced by large-diameter slurry shield is close to normal distribution.The results can provide scientific reference for the prediction and control of ground deformation induced by large-diameter slurry shield.