| Since the beginning of the 21st century,the transportation problems faced by urban development have become more and more serious.In order to alleviate the excessive pressure on the road,a large number of subway city subways have developed rapidly.In the process of subway construction,in order to facilitate people’s travel safety and improve transportation efficiency,the subway structure often needs to set up multiple entrances and exits and ventilation ducts.At this time,the open－cutting method cannot meet the actual requirements,and most areas usually use shallow buried method.Construction of structures such as street passages and ventilation ducts.The shallow burying method has a low cost,less demolition,and normal transportation without affecting the ground transportation during the construction process.However,the shallow burying method will cause disturbance to the undisturbed soil during construction,and cause surface deformation of the road surface when it is severe.Collapse and cracks will also tilt the adjacent building structure and destroy the underground water supply and power lines and communication lines.Therefore,the safety evaluation of the underground tunnel construction of subway stations is a major concern of scholars at home and abroad.This paper combines the example of the underground excavation channel project of the entrance and exit of the North Daying Street Station of Shenyang Metro Line 10 to study the displacement and deformation of the surrounding soil and adjacent structures by the CRD undercut construction method,and analyzes the undercut structure during the construction process.The degenerative laws of the surrounding soil and building structure,so as to evaluate the safety of shallow-buried excavation construction,and obtain reliable conclusions that are beneficial to construction control.The main research work of this paper is as follows:(1)Combining the existing domestic and foreign experts and scholars on the research on the influence of shallow buried tunneling construction on the deformation of surrounding soil and building structure,the current status of shallow buried tunneling construction technology in China is analyzed.Introduce several existing shallow buried and excavation construction methods and their respective advantages and disadvantages.(2)The on-site monitoring of the surrounding surface settlement during the shallow excavation of the CRD used in the project,the settlement of the vaulted tunnel,the clearance of the clearance,and the settlement of the adjacent building structure were carried out in time.Using the MIDAS/GTS geotechnical engineering finite element software to establish a three-dimensional model of the CRD shallow-buried tunnel itself and its surrounding buildings,and analyze the structure of the undercut channel and the deformation of the surrounding soil at each construction stage,the simulation clata will be obtained.Compare and analyze the actual monitoring data to verify the applicability of the model.(3)Based on the actual engineering CRD undercut construction method,the various construction steps and parameters are adjusted and simulated.The various factors for the simulation are:construction process,excavation step,grouting thickness and embedding depth.(4)The simulation data under the condition of each construction parameter after the modification is analyzed and compared with the monitoring data of the actual project,and the optimal construction parameters of the CRD construction method are obtained,and the original construction scheme is optimized.The MIDAS GTS NX software was used to establish a three-dimensional model of the subway station undercut channel based on the optimal parameters for safety analysis.Compared with the original scheme,the optimized scheme can significantly reduce the internal force and deformation of the tunnel and the surrounding soil and buildings during the construction process without significantly increasing the cost,and at the same time establish a good safety construction.basis. |
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