Study On The Impact Of Constructing A Deep And Wide Tunnel Beneath Existing Buildings

As a common type of urban subway station,large-span shallow buried underground excavation tunnels inevitably disturb the surrounding environment and buildings due to tunnel excavation.Excessive deformation and settlement will ultimately affect the safe use of buildings(structures)and the stability of the tunnel itself.How to determine the maximum impact of buildings(structures),analyzing the causes and laws of their impact,and summarize measures to reduce building deformation and tunnel construction safety are of great significance for urban subway construction.The excavation conditions of shallow buried tunnels are complex,and traditional experience is difficult to cover specific stratum and terrain engineering.This thesis determines the surface settlement laws of shallow buried tunnels in rock strata and overlying buildings by adding the parameters of the Gaussian equation applied to predict the ground settlement,and analyzes the deformation laws of buildings based on numerical analysis and elastoplastic theory.The basic content is as follows:(1)Based on the actual project of Yudaishan Station in the west extension section of Chongqing Metro Line 4,the analytic hierarchy process was used to screen out the influencing factors of large-span shallow buried underground excavation tunnel excavation.Combined with expert questionnaires,the comprehensive fuzzy evaluation method was used to grade the influencing factors of tunnel construction safety,and the specific objectives of the study was determined.(2)By using existing monitoring data to modify the Peck empirical formula,a correction formula combining with actual engineering conditions was derived,and other cross sections were used for verification to determine the surface settlement formula for shallow buried tunnels in accordance with sandstone strata.(3)On the basis of determining the factors that affect the construction of buildings during tunnel excavation,combined with on-site investigation,Flac3 D numerical model software was used to analyze the response of buildings during tunnel construction under different spatial positions of tunnels and buildings.The deformation and damage characteristics of buildings in different spatial positions and the changes in surface settlement under different building structural forms were discussed.(4)Based on the Yudai Mountain Station project of Chongqing Metro Line 4,combined with monitoring data,the influence of arch cover method and double side wall heading method on the settlement and deformation of the ground and buildings was calculated and analyzed,and reasonable measures to reduce building damage were proposed.