| Rock medium is predominantly fracture in non-soluble rock tunnel. Heterogeneity of fractured fissure determined heterogeneity of water enrichment. Characteristics of non-soluble rock tunnel water bursting are water-bursting quantity is not huge, but due to the water distribution inhomogeneous, and water-bursting position not sure, huge water- bursting is still possible happen in the watery structure parts when tunnel excavation and the risk is danger. As countries of railway and highway construction, how to accurately predict non-soluble rock tunnel water-bursting quantity and how to establish non-soluble rock tunnel risk evaluation system, thus evaluating the non-soluble rock tunnel water-bursting impacts on engineering and environment, puting forward effective prevention measures, and guiding tunnel design and construction, have important meaning to the geological disaster prevention of tunnel water-bursting.Based on the karst tunnel water-bursting calculation and risk evaluation, according to the characteristics of non-soluble rock medium, combining several typical non-soluble rock tunnel project examples, how to choose the calculation method is preliminary studied, non-soluble rock tunnel water-bursting hazard evaluation system is preliminary established.The research findings are described as follows:(1) Choose precipitation infiltration law, groundwater dynamical method, the gray system theory method and fuzzy mathematical method to calucalate the water-bursting quantity of four typical non-soluble rock tunnel named Wuzhi mountain tunnel, Balang mountain tunnel, Niba mountain tunnel, and Yangjia mountain tunnel. Analy the calculation accuracy control factors of non-soluble rock tunnel.(2) Based on the analysis of non-soluble rock tunnel disaster characteristics, choosing five main influence factors of non-soluble rock tunnel as rock permeability and mechanical properties, geological tectonic conditions, surface catchment conditions, the relationship between tunnel buried depth and underground water level, and the relationship between maximum principal stress and main structure, to be the evaluation indexes of non-soluble rock tunnel hazard risk.(3) Comprehensive consider the control function of fissure water occurrence and migration enrichment conditions to the non-soluble rock tunnel water-bursting disaster. Formed from the control and comprehensive reflection of the non-soluble rock tunnel water-bursting hazard chance and disaster risk factors, determine the criterion strata and index layer of the evaluation index system, put forward the comprehensive evaluation index of the non-soluble rock tunnel water-bursting disaster risk, choose the THR total score to represent disaster dangerous level.(4) According to the ripe experience of former geological hazard assessment, with reference to the current complex karst tunnel construction technology and the risk accept standard which is generally accepted to the engineering, non-soluble rock tunnel water-bursting hazard risk is divided into five level: risk extremely high area, risk high area, risk medium area, risk lower area and risk low area.(5) The weight of the non-soluble rock tunnel water-bursting disaster evaluation index is determined by using fuzzy comprehensive evaluation method and analytical hierarchy process method. The non-soluble rock tunnel water-bursting disaster risk assessment system is also established.(6) According to the analysis of non-soluble rock tunnel water-bursting quantity calculation accuracy, combining the hydrogeology conditions of the Gaoligong mountain servants tunnel zone, choose the goodman formula and dupuit formula from groundwater dynamical method to calculate the maximum and normal water-bursting quantity of non-soluble sections of Gaoligong mountain servants tunnel. The maximum water-bursting quantity is 101037 m~3/d and the normal water-bursting quantity is 81288m~3/d。(7) The non-soluble sections of Gaoligong mountain servants tunnel are risk assessed by using the non-soluble rock tunnel water-bursting disaster risk assessment system. Risk assessment results provide important basis for tunnel safety construction and disaster prevention. |
PDF Full Text Request