Analysis Of The Construction Scheme For Metro Station And Its Affiliated Structures Going Through Existing Bridge

With the continuous development of the social economy,there are more and more cities building subways in China.Due to the insufficiency of the previous subway construction planning,most cities did not consider reserving sufficient underground space for future subway construction during the construction of ground transportation,which made the construction of the subway adjacent to the existing structure more and more common,including the subway stations and their temporary construction.There are many types of risk sources such as subway stations and their temporary structures,and the construction methods are different,which have different influences on the existing structures.At present,there are few studies on the construction monitoring and impact of such projects in China,so the related problems need to be urgently solved.This paper is based on the construction of a subway station and its temporary structures adjacent to the existing four-span continuous beam bridge project.After the full investigation of existing bridge and subway engineering materials and extensive reading of relevant literature at home and abroad,combined with construction monitoring data and limited Meta-simulation,in-depth study on the allowable deformation of existing structures and the construction of new structures,the paper provides reasonable suggestions for the construction of similar projects in the future.The main research results of this paper are as follows:(1)On the basis of extensive reading of relevant literatures at home and abroad,the paper summarizes the influence mechanism about open excavation and undercut construction on surrounding soil and existing bridges,which provides theoretical basis for subsequent monitoring data analysis and numerical calculation analysis.(2)Under the premise of passing through the pre-work inspection report to clarify that the bridge is in good condition,based on the existing bridge structure design and completion data,the "load-structure" model for the bridge is established by using Midas Civil software to study the deformation and settlement of the bridge.The stress state of the beam under the condition is determined by the finite element calculation and related specifications and in this way determine the allowable deformation and settlement limit values.In view of the relatively simple structure of the bridge and the relatively clear relationship between the underground engineering and the bridge position,under the premise of preliminarily predicting the deformation and settlement characteristics of the bridge during the construction of the underground engineering,the control value of the deformation and settlement of the bridge is determined according to the above limit values.(3)The monitoring data of bridge deformation and surface subsidence during the construction of temporary structures and metro station pilot hole are collected and analyzed,and the effects of various structures on the surface and existing bridge structure are studied.(4)The Midas GTS software is used to establish a “stratigraphic-structure” model for existing bridge and new subway station and its temporary construction,simulating theconstruction process of the project within the monitoring data.The monitoring results are used to optimize the modeling method,so that the calculation results are as close as possible to the monitoring results,which ensures the rationality of the model calculation parameter setting and the construction process simulation method.Under the premise of uniform distribution of engineering soil conditions and the same applies to the completed construction and the non-application construction method,the rationality of subsequent calculation results are also guaranteed.Through data comparison,the difference and relationship between finite element calculation results and monitoring results are analyzed.(5)The optimized model is used to simulate the subsequent engineering construction process.The influence of the construction of the post-station station on the bridge structure is analyzed,and the lifting measures to ensure the safe operation of the bridge are studied.