| Yichang-Wanzhou railway is a major railway project through karst areas. It has a total of 159 tunnels with 339 km long. Tunnels are accounting for 60% longth of the line. The karst water inrush geological disasters is an important factor in construction safety. There are eight mainly typical karst tunnel which be as the researching target and basic information Source. There are Baziling tunnel, Yesanguan tunnel, Qiyueshan tunnel, Bieyancao tunnel, Jinzishan tunnel, Dazhiping tunnel, Maluqing tunnel, Yunwushan tunnel. On the basis of investigating to these eight typical karst tunnel projects, the Yichang-Wanzhou Railway tunnel karst water inrush geological hazards mechanism and risk assessment method during construction is being studied.1, Through on-site research and data analysis, systematic investigation and analysis the basic conditions of the eight karst tunnels are been done. The basic features of construction exposed karst are been investigated.2, The mainly geological hazards characteristics of these eight typical karst tunnel are been investigated. It Included disaster specific construction environment investigation and analysis of formation rock type, geological structure, groundwater seepage and other characteristics.3, The mainly geological factors of affecting and controlling the disaster are been studied. The karst cave distributation is the basis of karst disaster happen. Through the study, the relationship between the huge karst cave forming condition and the impact of basic conditions of the deep geological disasters, karst topography, rock structural features, fold shape, strata and the fault occurrence, groundwater flow channels and other factors related to the rule.4, The karst water inrush disaster style is been researched. According different rules the different karst water inrush style are been got. The rule are of water inrush size,material composition in water, the karst ground water or underground pipe burst time and the disaster result. The calculating method of karst water inrush is been found and used in yichang-wanzhou railway project. The geological disasters risk classification criterion has been established. According to yichang-wanzhou railway engineering practice, the risk grade is been divided with high risk, middle risk and low risk degree.5, The geological mechanism analysis method of karst water inrush risk assessment is the first time to be proposed. The guidelines for the application of the method,evaluation procedures and application technology are establishmented too. These method is used in evaluated the Qiyueshan, Baziling and yesanguan three key dangerous tunnels. The most dangerous sections of these three tunnels are been analyzed and evaluated. The evaluation results in practical engineering are applied and verified.6, The application of information analysis method in the water in evaluating risk of karst water hazard is studied. The karst geological hazard rating degree is as the evaluation target layer in this course. The lithology, geological structure, topography, surface water system, groundwater system and karst elevation are be take as criterion layer. The other 14 factors which are related to the karst water inrush disaster are been called the second affecting factors. The layer degree model is been built. information analysis method is been used to determine the weight affecting factors. Applied role of index to determine risk degree. This method is used in Yichang-wanzhou railway project and as an example of practical application.7, The geological characteristics of karst hazards Index are made as the base. Applied expert system method to research exploreing design program and software platform. The synthesized analyzed index system of geological disasters are been set. A comprehensive prediction of karst water inrush geological disasters expert system is been developed. This method is used in Yichang-wanzhou railway project and as an example of practical application.The research works in this papers is based on the in site investigating to Yichang-wanzhou railway. According to on field survey of the karst water inrush geological hazards materials, the forming rules of karst water inrush geological hazards are been studied. The evaluating criteria is established. The combination of geological mechanism analysis and quantitative calculation was studied to evaluating the karst water burst geological hazards. A comprehensive evaluation expert system of risk assessment was explored. Research results used in engineering practice, not only for the specific Yichang-wanzhou railway Project, it has a direct role in disaster prevention, but also in the future construction of similar projects in karst areas it have important guiding significance.
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