The Safety Impact And Risk Analysis Of Deep Foundation Construction Near Subway Tunnel

Over the past few years,the subway has been developing rapidly in major cities because of its safety,reliability,punctuality,efficiency,and convenience.In order to make full ues of the subway,the land around the subway has been developed and used on a large scale.Different from general buildings,the allowed deformation of subway is under extremely strict control.The deep foundation engineering will affect the structure and operational safety of adjacent subway tunnels inevitably.How to evaluate the impact of deep foundation on the safety of nearby underground tunnels and risk analysis and optimizing inspection sequence accurately has become an important engineering problem in urban construction.This thesis is under such a background that the Wuhan the mixc mall project near to the Metro Line 7.Based on the deformation law of the deep foundation retaining construction,the influence of the displacement and convergence deformation of the subway tunnel structure,the construction risk analysis and the optimization of the inspection sequence of risk factors,the impaction of deep foundation construction to near subway tunnels,risk analysis and accident rike diagnosis and other related issues are systematically studied.Mainly have the following research work:(1)Analysis of measured data of deep foundation and adjacent subway tunnelsBased on the actual measurement data of the mixc mall engineering project,the effects of the deep foundation retaining structure,the deep soil and the horizontal displacement of the crown beam,the vertical displacement of the column and the deformation of the surrounding ground settlement with the construction conditions are studied.The influence of the settlement,horizontal displacement and convergence of adjacent subway tunnel vaults with the deformation of the construction conditions and the overall distribution law are analyzed.(2)Numerical simulation analysis of deep foundation and adjacent subway tunnelsCombining with the mixc mall engineering project,FLAC 3D finite element software was used to realize the dynamic numerical simulation of the entire excavation process of the deep foundation.The influence of the deformation of the retaining structure and the column piles with the construction conditions and the distribution of the final settlement of the surrounding ground are analyzed.Emphasis is placed on the influence of the subway tunnel vault settlement,horizontal displacement and convergence with the deformation of the construction conditions and the overall distribution law,combining with the numerical results and monitoring data,comparing the maximum value of the analysis results and the monitoring data with the control value to verify the reasonability and accuracy of the numerical calculation.(3)Risk analysis of combining bayesian network based on Netica and fuzzy comprehensive evaluation methodThe risk factors of deep foundation engineering adjacent to the subway tunnel structure are identified through bayesian network,and the overall evaluation grade of deep foundation engineering and the comprehensive evaluation grade of root nodes are obtained through fuzzy comprehensive evaluation method.Then the posterior probability of each node and the probability level of deep foundation engineering accident occurrence are obtained through the Bayesian network based on Netica software.Combining the comprehensive evaluation level and posterior probability of the root node,the comprehensive importance level of all root nodes is obtained,which is used as the basis for the priority inspection and diagnosis of risk factors when an engineering accident occurs and verifying the advantages of this method.