邻近既有深基坑的盾构法隧道施工地层变位分析

Analysis of Stratum Deformation Induced by Shield Construction Adjacent to an Existing Deep Foundation Pit

文章针对盾构隧道邻近深基坑推进的工况,进行室内缩尺模型试验,并建立了对应工况下的盾构隧道-土体-基坑围护结构三部分共同作用的三维有限元计算模型。通过对比同一工况下的室内模型试验和数值计算结果,验证了三维数值分析的可行性和可靠性;得到了邻近既有深基坑的盾构法隧道施工引起周边地表沉降的分布特点及其变化规律;分析了盾构隧道开挖引起的横断面不同深度处地层位移的特点;分析了隧道上方的地表沉降分布受邻近既有基坑的影响及沉降值随盾构隧道推进进度的变化规律,得到了盾构隧道对基坑围护结构的位移影响情况;并提出了盾构隧道施工过程中对周边地表沉降、地层变位及基坑围护结构位移与变形进行实时监测的建议。

In light of the construction of a shield tunnel adjacent to an existing deep foundation pit, a scaled model test is conducted and a 3D FEM calculation model is established regarding the combined functions of the tunnel, soil mass and enclosure of the deep foundation pit. Based on a comparison of an indoor model test and numerical calculation results, the feasibility and reliability of the 3D numerical analysis is verified; the distribution characteristics and variation law of the surrounding surface settlements induced by shield tunnel construction adjacent to an existing deep foundation pit are obtained; shield tunnel construction induced displacement characteristics of the stratum of cross sections at different depths, the surface settlement distribution affected by the adjacent existing foundation pit, and the law of settlement varying with shield tunnel driving are analyzed; the displacement of the foundation pit enclosure affected by the shield tunnel is determined; and real-time monitoring is suggested for the surface settlement, stratum deformation and displacement and deformation of the foundation pit enclosure during shield tunnel construction.