复合地层盾构穿越构筑物群扰动规律及桩基隔断效应分析

Analysis on Disturbance Law and Pile Barrier Effect of Shield Crossing Underground Structures in Composite Strata

摘要:

依托某盾构穿越工程，建立了盾构同时穿越桩基和多条隧道的数值模型并进行了验证。总结了盾构穿越诱发的地表沉降、既有隧道收敛和桩基变形规律，探明了既有桩基对扰动传递的隔断效应，并通过土体应力路径分析揭示了 桩?土?隧相互作用机制。结果表明：桩基的存在减小了隧道施工引起的地表沉降和沉降槽宽度，改变了既有隧道的变形模式，对扰动传递具有明显的隔断效应；受既有隧道和盾构施工的双重影响，两者间桩基承台的横向倾斜出现多个变形阶段，桩身上部出现较大的横向位移，而桩底位移较小；桩基、隧道和土体的刚度差异是桩?土?隧间复杂相互作用的根本原因。

Abstract:

Based on a shield tunnel project that simultaneously crosses multiple piles and existing tunnels， a numerical model was built and verified. The laws of surface settlement， convergence of existing tunnels and pile deformation induced by shield tunneling were summarized via the simulation. In addition， the barrier effect of piles on the transmission of disturbance was highlighted. The pile-soil-tunnel interaction mechanism was also revealed with the analysis of stress path of soils. The results show that the existence of pile foundation reduces the surface settlement and the width of settlement trough induced by shield tunneling， and changes the deformation mode of the existing tunnels. All these differences indicate that the pile has obvious barrier effect on the transmission of disturbance. A large lateral displacement occurs at the top part of piles and the lateral inclination of the pile cap undergoes complex trends， which is the results of the existing tunnel and shield tunneling process. The stiffness difference among piles， tunnels and soils is the basic reason for pile-soil-tunnel interactions.