上方明挖基坑及盾构隧道施工对已运营地铁隧道变形影响分析

Analysis of the influence of open-cut foundation pit and shield tunnel construction on the deformation of operating subway tunnels

本文以已运营地铁隧道上方基坑明挖和隧道盾构施工两种工况相结合的某工程为背景,研究了地铁隧道及其附属结构在各种施工工况下的响应。利用有限元软件Midas建立三维有限元模型,并在模型中还原基坑及盾构隧道施工的各工况,研究分析控制性工况下地铁隧道及其附属结构的响应。结果表明,在地铁隧道上方明挖基坑和盾构隧道的双重施工中,采用高结构刚度的支护形式和对地铁隧道周边土进行MJS(微扰动高压旋喷桩)加固的方式,可以有效控制基坑开挖和盾构隧道施工对已运营地铁隧道及其附属结构的影响。同时,通过对比分析数值模拟结果与施工现场实测数据,验证了基于HS-Small小应变弹塑性本构建立的有限元模型可以更好地实现复杂条件下基坑、盾构施工对周边环境的影响。

Based on the project combination of two working conditions:open excavation and tunnel shield construction,the response of subway tunnel and its affiliated structure under various construction conditions is studied.Threedimensional finite element model is established by Midas,and reduction of foundation pit in the model and the shield tunnel construction of the operating mode,the analysis of working condition of controlling the response of subway tunnel and its adjacent structures.As the results shown,in the dual construction of the foundation pit and shield tunnel above the subway tunnel,the influence for foundation pit excavation and shield tunnel construction on the existing metro tunnel and its affiliated structures can be effectively controlled by adopting the high structural stiffness support form and using the MJS(micro-disturbance high-pressure rotary jet grouting pile)to reinforce the soil around the metro tunnel.At the same time,by comparing the numerical simulation results with the measured data in the construction site,it is verified that the finite element model established based on hS-Small Small strain elastic-plastic constitutive model can better realize the influence of foundation pit and shield construction on the surrounding environment under complex conditions.