复合地层双线TBM隧道施工对临近建筑物影响

Research on the Influence of Twin Shield Tunnel TBM Construction on the Existing Structures in Composite Ground

以重庆轨道环线区间隧道下穿既有结构为背景,利用数值分析与现场监控量测相结合的方法,对复合地层双线TBM隧道施工影响下围岩及既有结构的变形进行了深入研究。数值计算结果表明,右线开挖引起的建筑物沉降远大于左线引起的沉降,隧道施工对既有结构的沉降影响与沉降槽宽度有关。TBM施工对建筑物桩基的变形受力影响与其距隧道中线距离密切相关,离隧道中线越近,桩基沉降越大;不同围岩区域桩身轴力变化趋势也不相同,主要与桩身周边土体相对竖向位移有关。现场监测结果表明,受地层差异及既有结构刚度的影响,双线地表沉降呈偏态的单凹槽状。TBM到达前,建筑物向远离隧道方向倾斜,隧道下穿过程及下穿后,建筑物向隧道方向倾斜。综合数值计算结果和现场监控量测数据,二者所反映的规律基本相同,为今后TBM在类似工程环境中的应用提供借鉴。

Based on a twin shield tunnel of Chongqing Transit Circle Line crossing existing structures,using 3D numerical simulation and site monitoring method,the deformation characteristics of the existing structures and surrounding rock affected by the construction of twin shield tunnel in composite ground are studied. The simulation results show that the foundation deformation of the building affected by constructing the right shield tunnel is larger than that caused by the left shield tunneling. Settlement of the existing structures is influenced greatly by the width of settlement trough. The stress and strain of building pile foundation affected by the constructing depend mainly on the pile-tunnel distance,the shorter the distance,the larger the deformation of pile. The change trends of tunneling induced pile internal force are various in different regions,which mainly depend on the relative vertical displacement of surrounding soil. Site monitoring results show that,lateral surface subsidence is presented as a single groove shape,which may be explained as that soil stiffness is strengthened by the existing structures,and stratigraphic differences are performed. The building inclined to the direction away from the tunnel prior to the shield closing to the building,while the building inclined towards the tunnel during shield crossing. The simulation and site monitoring results agree well. The conclusion has potential applications to future similar urban construction engineering using TBM.