Analysis For Water Burst Mechanism And Study On Mechanical Features Of Tunnel Lining In Water Filled Karst Area

Around the world, karst region distributes most widely in China, and with the fast development of national economy, more and more underground engineerings are being constructed in karst region, therefore the stability of karst tunnel has been a pressing problem in the course of engineering construction. To accomplish the construction, we must figure out the techniques for dealing with the effect of karst to engineering and the geologic hazard caused by construction. Therefore, based on extensive literature review and summarized in detail, the problem of karst tunnel is studied systematically by means of numerical analysis and model test.First of all, the mechanism of the karst water burst was analyzed, and summarized them in tensioning failure of the water-sealing rock columns,the shearing failure of the fissures,the hydrodynamic expansion of the fissures and the stability-losing failure of the ground, and the primary factors which have the most effect on the karst water burst were listed as follows, geological condition,atmospheric temperature, rainfall and rainfall intensity and the stress distribution caused by the construction.Secondly, the thesis adopts the finite element analysis software to proceeding numerical simulation computation for the influence of water pressure filled caves to the displacement and internal force of supporting structure of the tunnels.based on class IV surrounding rocks numerical simulation computation was proceeded while water pressure filled karst caves on the top of the tunnel,beside the tunnel,down below the tunnel. compared with the case of without caves surround the tunnel, a number of useful laws were obtained which can be useful in design, construction and research of similar tunnels by analysis the different influence of different position size and water pressure of the concealed Karst caves on displacement field and the internal force of support structure for tunnel.At last, Through analysis the model test results, the influence of different water pressure of the caves to the internal force of support structure for tunnel when the water pressure filled caves on the top of the tunnel,beside the tunnel,down below the tunnel is summarized in laws. Compare these laws with the result obtained by numerical analysis, we found that the two methods came to the same conclusion.