Construction Method And Mechanical Analysis Of Shield Tunnel Support System In Karst Section

With the rapid development of tunnel engineering today,with the increasing depth of the tunnel and the increasing complexity of the stratum structure,the safety accidents in karst section tunnel construction are common.Therefore,it is very necessary to study the supporting system of deepening karst tunnel.In this paper,the research status of shield tunnel support system in karst section is comprehensively summarized.Based on the understanding of karst geology and adverse working conditions,the construction method of special support system for karst tunnel was put forward,and then the key influencing factors in the support system were studied in combination with specific engineering background,so as to provide meaningful experience reference and construction guidance for shield tunneling in karst section in the future.The details are as follows:(1)Firstly,the research significance and research object of this paper are explained.The relevant research status of karst shield tunnel support system is summarized and briefly introduced.The research status of karst formation conditions,chemical composition,hydrology and water quality,stratigraphic structure,climate characteristics,distribution characteristics and other aspects is systematically sorted and analyzed.(2)The background of Hejiang Tunnel project in Hengyang was explained and summarized.The molcoulomb model in FLAC3 D was used to establish the numerical model of karst cave-tunnel for analysis.(3)The karst-"total amsolution" tunnel system method is proposed,and the relevant conditions within the project and the region are divided into two parts: natural system and man-made system.It also makes clear the components of five kinds of information in natural system,the main body of five functional objects in human system,four main engineering bodies,three major disaster causes and six major consideration factors.(4)Based on the basic background of the construction of Hejiang Tunnel in Hengyang,the critical factors affecting the critical safety distance between the karst cave and the tunnel in the support system were analyzed by combining the finite difference software FLAC3 D and orthogonal test method(5)The displacement and stress cloud maps of the corresponding support system were obtained after the application of the pipe sheet support structure,and the response rules were summarized to provide reference and experience for tunnel construction in karst section.