Study On Safe Distance Between Concealed Carst Cave And Tunnel And It’s Intelligent Prediction Model

It is a troublesome technical problems how to reasonably determine the safe distance between tunnel and karst cave when concealed karst cave exist around the tunnel. It is not only linked to whether the tunnel can be successfully construction and security operations, but also determines the tunnel length and depth to some exten. The distance of the tunnel avoiding around karst cave is smaller when the distance between tunnel and karst cave is smaller, and the tunnel is shorter, then the project cost is lower, but the risk of tunnel destabilization is bigger also. The Study on safe distance between concealed carst cave and tunnel and it’s intelligent prediction model is in this paper, which mainly contains as follow:(1) This paper analyzes the karst cave developmente characteristics, size and space distribution through collecting the data of karst tunnel in southwest China and the survey on Yi-Wan railway tunnels, Summarizes the three common position relations of concealed karst cave to the tunnel.in the tunnel engineering. Based on this, big span concealed karst cave-tunnel analysis model and medium-small sized span concealed cave-tunnel analysis model are built.(2) The destabilization mechanism of rock stratum between the big span concealed cave and tunnel is analyzed. Based on the elastic beams plate theory, the strained condition of top(bottom and lateral)concealed karst cave mechanical model is respectively analyzed, then the safe distance calculation formula of concealed karst cave and tunnel are deduced, which is veried by engineering example.(3) The research methods of safe distance between concealed karst cave and tunnel is put forward based on the catastrophe theory. The stability of rock between concealed karst cave and tunnel is evaluated by the catastrophe theory. The catastrophe mode of rock strata system destabilization is established through the research of total potential energy between karst cave and tunnel, then the safe distance calculation formula(contains instability mechanical conditions and instability criterion)of concealed karst cave and tunnel are deduced.(4) The simulation method of the process of tunnel construction under the influence of concealed karst cave is discussed. The safe distance criterion of concealed karst cave and tunne is put forward based on safety factor catastrophe and energy catastrophe. The factors of safe distance between concealed karst cave and tunne is analyzed. (5) The finite element numerical experiment model is established which approximate the actual problem. The factors value range and level division of safe distance between concealed karst cave and tunne are confirmed, then30level numerical simulation plan of safe distance between concealed karst cave and tunne are designed by uniform design method.(6) The numerical simulation method of safe distance between concealed karst cave and tunnel is put forward based on the energy catastrophe, dichotomy the plastic zone through and the shear strength reduction safety factor catastrophe, the numerical simulation results based on the energy catastrophe are more reasonable by analysis the three methods, then the sample data of the effect factors and safe distance is obtained.(7) The forecasting method of safe distance between concealed karst cave and tunnel is put forward based on SVM. program in MATLAB, the SVM samples gaining from simulation data are trained, then the intelligent forecast model of afe distance between concealed karst cave and tunnel is gained based on SVM. By applying the forecasting models to the real projects of karst tunnels, the reliability of the results is proven, which has an important meaning for reasonable selection safe distance between concealed karst cave and tunnel, and promote the karst tunnel construction and design to intelligent development...