A Study On Advanced Geological Forecast Techniques For Tunnel Karst Collapse And Corresponding Solutions

Karst problem has always been a problem in the construction of tunnel in karst region.Study on forecast techniques for karst collapse and corresponding solutions is of great importance to tunnel construction in karst areas, in that karst geological disasters like water bursting, mud gushing and collapse commonly seen in the construction sites always lead to serious casualties and great economic loss, which has long haunted engineers.Karst areas are widely distributed in China, covering 340km2, more than one third of China's land area. In railway tunnel construction in the southwest and mid-south regions,engineers have worked out corresponding solutions to different problems of karst collapse they encountered, thus they have gathered rich experience. And the fundamental solution lies in solving the problems of karst water, karst cave infilling and karst empty caves.This thesis, based on a great number of authoritative documents concerning the subject,analyzes the effect of karst caves over the stability of surrounding rock, and concludes the effect rules in terms of the stress and displacement, with an aim to work out some forecast techniques for karst collapse and corresponding solutions. Key points are as follows.(1) Introducing advantages and disadvantages of various forecast techniques, especially the advanced geological forecast technique for karst.(2) Analyzing the effect rules of empty karst caves, on the lateral, top or bottom of a tunnel and at different distances from the tunnel, over the surrounding rock in terms of the stress and displacement by numerical simulation of FLAC3 D software, with GuanLing NO.1Tunnel in Guizhou Province as the study object.(3) Putting forward solutions to different kinds of karst collapse and offering suggestions for karst tunnel design and construction, after discussing those problems of different kinds based on the analysis above and current experience.Through researches on those aspects above, the thesis aims to put forward a systematic and practical construction technique which integrates advantages of various techniques, so as to better forecast tunnel karst collapse and offer corresponding solutions.