基于FLAC^(3D)的砂质淤泥质土层地铁施工影响因素分析

Analysis of influencing factors for subway construction in special soil layers based on FLAC^(3D)

为分析叠交地铁施工中既有隧道变形的影响因素,依托苏州市轨道交通S1线工程S1-TS-05标段,针对在砂质淤泥质土层中盾构上穿施工导致的既有隧道的沉降与变形,采用数值模拟方法分析隧道几何参数、空间位置、地层参数等因素对既有隧道的影响,结合现场监测验证数值计算的准确性。研究结果表明:在砂质淤泥质土层盾构上穿施工中,既有隧道的位移和管片变形以竖向沉降为主,且沉降量随着盾构直径的增大而增大,随着覆土层厚度、新旧隧道净距、下穿角度,以及地层弹性模量的增大而减小。现场监测数据与模拟结果较为吻合,既有隧道位移与距叠交中心距离呈负相关关系。研究结论可为同类型地层条件下叠交地铁隧道盾构施工变形控制提供参考。

In order to analyze the influencing factors of existing tunnel deformation in overlapping subway construction,based on the S1-TS-05 section of Suzhou Metro Line S1 project,numerical simulation methods were used to analyze the influence of tunnel geometric parameters,spatial position,and geological parameters on the settlement and deformation of existing tunnels caused by shield tunneling in sandy and muddy soil layers.The accuracy of numerical calculations was verified through on-site monitoring.The research results indicate that in the construction of shield tunneling on sandy and muddy soil layers,the displacement and deformation of existing tunnels are mainly vertical settlement,and the settlement amount increases with the increase of shield tunnel diameter,but decreases with the increase of cover layer thickness,net distance between new and old tunnels,underpass angle,and elastic modulus of the formation.The on-site monitoring data is in good agreement with the simulation results,and there is a negative correlation between the displacement of the existing tunnel and the distance from the overlapping center.The research conclusion provides a reference for deformation control during shield tunneling of overlapping subway tunnels under the same type of geological conditions.