Analysis of the impact characteristics of different cave positions on the safety of tunnels in karst regions
The problem of mud and water inrush in karst tunnels has always been a key and difficult point in engineering construction,directly affecting project progress and construction safety,and de-serves special attention and in-depth research.Based on the actual project of railway tunnel crossing karst areas,the Qinchu karst tunnel of Xi'an Shiyan high-speed railway was taken as the research pro-totype.Firstly,a three-dimensional karst tunnel fluid structure coupling model was established using Abaqus finite element software.Then,reasonable seepage boundary conditions were selected to restore the tunnel prototype.Finally,the finite element model was verified based on on-site monitoring results to explore the influence of different karst positions and cave diameters on the settlement and deforma-tion laws of railway tunnels.The results indicate that:The distance between the tunnel and the karst cave,as well as the size of the karst cave,have a dual and diverse impact on the settlement of the tun-nel arch.However,the increase in the size of karst caves will exacerbate ground subsidence and de-formation,with the largest impact on ground subsidence occurring when the caves are located on the side of the tunnel.When the karst cave is located at the bottom of the tunnel,the ground settlement val-ue is second;When the karst cave is located at the top of the tunnel,the corresponding ground settle-ment value is the smallest;When the karst cave is located on the side of the tunnel,the deformation of the tunnel arch crown and left and right arch waists has the greatest impact.As the diameter of the lat-eral karst cave increases,the deformation of the top and arch structures on both sides of the tunnel also increases,leading to a tendency for the inverted arch at the bottom of the tunnel to rise.The research results provide a basis for the safety of tunnel construction projects in karst areas,and also provide a certain reference for tunnel safety construction technology.
karst tunnelfluid structure coupling modelwaterproof rock disccave locationcave size
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