The Mechanism and Numerical Simulation Analysis of Water Bursting in Filling Karst Tunnel

In order to investigate the mechanism and the process of water bursting in filling karst tunnel, based on the geological defect of karst water bursting formations, the instability model of filling karst conduit is built. There are the seepage failure of permeable media, the sliding instability of impermeable media and the seepage and sliding instability of low-permeable media. The corresponding instability criterions of these models are obtained by deriving their mechanics formulas. Based on the karst water bursting in Fenshuiao tunnel project, the mechanism and numerical simulation analysis of its water bursting process are analyzed. The safety factor of filling of karst conduit is 0.502 which indicates that filling of karst conduit is instable. This analysis result is in accord with the actual situation of water bursting. The process of karst water bursting is simulated by Fast Lagrangian Analysis of Continua (FLAC^3D) which shows the whole process of water bursting in karst conduit.