| Foundation pit excavation unloading will cause deformation of adjacent existing tunnels,which will have certain impact on its normal operation and safety and stability.Therefore,it is important to study the impact of excavation.With the continuous deepening of urbanization in China,deep foundation pit projects are emerging one after another,and the excavation of subway pits operated by the side is a common one.This paper analyzes the predecessors' research on relevant theories and practices,and summarizes the inadequacies and problems that still need to be improved.Taking the deep foundation pit project near Line 2 of Guangzhou Baiyun Metro Area as an example,the finite element software is used to simulate the whole process of foundation pit excavation,and the influence of excavation unloading on the deformation of subway tunnel is also studied.The design,construction and monitoring of the project provide certain reference and reference.The specific work content is as follows :(1)Taking the foundation pit of No.2 line of Baiyun District of Guangzhou as the research background,the finite element software MIDAS/GTS was used to simulate the whole process of foundation pit excavation,and the influence of excavation on the side subway was studied.The settlement of the earth's surface,the deformation of the supporting structure,and the lateral deformation and longitudinal displacement of the tunnel are analyzed separately.Then based on the original model,the scheme of sensitivity analysis of geotechnical parameters is designed,and the order of sensitivity of each parameter is obtained.(2)Based on the research of foundation pit engineering and numerical simulation,combined with the design of orthogonal test method,the horizontal clearance of tunnel and ground wall,the height difference of foundation pit tunnel,the cross-sectional area of inner support and the elasticity of ground-connected wall are studied respectively.The influence of modulus on the deformation of the tunnel.According to the design scheme,a series of finiteelement models are established and calculated,and the results are analyzed by range analysis and variance analysis.The influence law and significance of each factor are obtained.(3)In order to avoid the occurrence of engineering accidents,on the basis of the above work,through the finite element simulation calculation,combined with the relevant practical engineering application,the reinforcement of the foundation pit foundation and the reinforcement of the tunnel surrounding the tunnel are studied respectively.Control situation.Then select a more effective reinforcement scheme and analyze its effect on tunnel deformation control. |
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