Research On Pile Foundation Underpinning Technology Of Underpass In Existing Buildings

With the rapid development of urban highway tunnels,there are more and more engineering cases in which tunnels are worn under existing buildings.In the process of tunneling under existing buildings,the excavation of the soil will inevitably affect the surface and existing buildings.In order to reduce this impact,basic underpinning or foundation reinforcement must be carried out.Many buildings in the city use pile foundations,so it is necessary to study the tunnel underpinning technology of existing buildings.This paper first introduces the research status of tunnel underpinning technology of pile foundation under existing buildings,which introduces the form of undercutting of undercut tunnels and undercut tunnels,and analyzes tunnels and surface buildings.The mechanism of interaction.Secondly,taking the extension of the Kangwang Road extension tunnel to the pile foundation of the green building as an example,through the investigation of the domestic standard and the control standards of the urban engineering experience,the difference between the surface settlement and the adjacent column foundation during the construction of the tunnel under the green building was determined.Settlement control standard;through the numerical simulation,the design optimization and construction safety analysis of the tunnel undercutting greening building plan were carried out.Taking the reinforcement of the Kangwang Road extension tunnel under the Dongfeng West Road viaduct foundation reinforcement and the Kangwang Road extension tunnel under the Guangyuan West Road overpass as an example,the bridge construction under the tunnel was determined through the investigation of the domestic standard and the control standards of the urban engineering experience.In the process,the surface settlement and the differential settlement control standard of adjacent piers are analyzed.Through numerical simulation,the situation of tunnel undercutting under the bridge under various working conditions is analyzed,and the design of tunnel undercut excavation reinforcement scheme is optimized.And construction safety analysis.Finally,through engineering practice,the construction sequence,method construction and construction monitoring plan of the replacement beam were determined.Through this research,the basic underpin can better control the tunnel construction deformation as an engineering structural measure.The research results provide important technical support for the engineering design optimization,and also provide reference for similar engineering construction.