| With the continuous development of urban-rail-transit construction in China,there are more and more cases of subway tunnel underneath-passing existing structures or undercrossing structures under construction,such as underneath-passing high-rise buildings,residential buildings,intercity railways,etc.When the shield-tunnel underneath-passing the structure,it may cause ground settlement due to stratum disturbance and deformation of the structure,and it may also affect the existing pile foundation,which has a great impact on the surrounding environment of the project.Especially,it is difficult to guarantee the safety of the existing surface structure and the construction of the subway shield tunnel when it penetrates the building under construction.This paper aims to stud the influence of subway tunnel underneath-passing the building on the surrounding environment,construction safety and construction risk.Based on the research status at home and abroad,this paper studies the construction technology and management of shield tunnel.The main contents are as follows:(1)The shield tunnel of Guangfo-Metro-Line 3 underneath-passing a large-scale comprehensive commercial complex under construction(hereinafter referred to as "Large-Project under construction")is selected as the analysis object.Combined with the actual situation of engineering cases,the scheme of "pile foundation + supporting beam" is selected by using AHP,and the problems that need to be studied and analyzed are put forward.(2)Midas-GTS software was used to establish a Three-Dimensional finite element model,and the calculation area,load and boundary conditions of Midas-GTS modeling were determined.The soil layer,building structure,tunnel structure parameters and constitutive relations related to the modeling were defined according to engineering cases.(3)Based on the three-dimensional finite element model established by Midas-GTS,the influence of tunnel construction on Large-Project under construction(horizontal displacement of pile foundation,vertical displacement of basement,influence of axial force and bending moment of pile foundation)is analyzed.(4)Based on the three-dimensional finite element model established by Midas-GTS,the influence of Large-Project under construction and shield tunnel synchronous construction on shield tunnel construction(the influence of displacement distribution,vertical displacement and horizontal displacement of tunnel tube slices)is analyzed.Corresponding constructionmanagement safety and quality measures are put forwarded.(5)After modeling analysis of Midas-GTS,it is concluded that the scheme of "pile foundation + underpinning beam" can effectively reduce the adverse impact between shield tunnel and Large-Project under construction.The simultaneous construction of shield tunnel and large projects under construction has little influence on the construction safety and is basically feasible.The scheme of "pile foundation + underpinning beam" can be given priority when the project scale is large and the construction conditions and economic conditions permit. |
