Analysis And Risk Evaluation Of The Construction Deformation Law Of The Underpass Building Subway Station

Subway station construction,often will be affected by surrounding the complex environmental impact,inevitably need to wear under the existing lines,underground pipe rack,building and other environmental facilities,under such wear process can directly damage formation as the original stress balance,easy to cause of formation and its surrounding environment facilities of secondary sedimentation,even deformation.This requires that in the process of subway station construction,not only the quality of the station itself should be guaranteed to meet the standard,but also the environment and the functions of the structures should be intact.Therefore,it is important to analyze and evaluate the influence mechanism of subway station underpass building.Under this premise,this study has the following results:(1)Technical research on the mutual influence of station underground excavation engineering,strata and buildings.On the basis of fully absorbing the academic achievements of experts and scholars at home and abroad,the influence mechanism of the form of building damage,influence factors of buildings and structure deformation.It provides theoretical support for the post-text monitoring and simulation research.(2)Monitoring data analysis of subway stations under buildings.Combined with the engineering practice of a station of Dalian Metro Line 5,the deformation monitoring scheme of the station excavation is analyzed,the key monitoring data are extracted,and the deformation and settlement rules of the key components and buildings of the station at different construction nodes are summarized.It is further concluded that the removal of support and the excavation of core soil are the main factors causing the settlement of the station and the ground.(3)Study on numerical simulation of underground excavation through building station.Based on the interaction principle of soil-station structure-building foundation,the model of underground excavation through building with arch cover method is established by simulation software.Base of headroom convergence,vault settlement,displacement and ground settlement and building foundation settlement data is analyzed,the results show that the arch cover method is applied,the strata,the settlement of surrounding rock and buildings have the closest relations with middle drift excavation,the surface subsidence induced during the process of construction accounted for 80.1% of the total settlement,pilot tunnel excavation on the station and the surface subsidence about minimal impact.The overall law is also consistent with the monitoring data.Finally,the primary and secondary order of the influence of the main processes on the surface settlement is obtained.(4)Improving the matter-element evidence theory for building risk assessment.Based on the results of theoretical analysis,simulation and actual monitoring,a risk assessment method based on the combination of matter element theory and evidence theory is proposed,and a risk assessment model is constructed.The results show that the stratum loss and overburden ratio caused by the middle guide tunnel excavation are the most sensitive factors affecting the safety of the underpass building.Through analyzing the law of its influence,the feasibility measures are put forward from the perspective of building and construction,and the practice is carried out to ensure the safety of the construction of the station section.