Study On Deeply Buried Tunnelling Water Burst Mechanism And Treatment Technique

Karst is one of the common geological hazards in the construction of mountain tunnel in China, and is also generally acknowledged one of the world-wide problems in domestic and international project. Based on the data collection and extensive literature study, the researches carried out in this paper will use a combination method including testing research, theoretical analysis and numerical simulation, and according to the supper karst water burst of Maluqing Tunnel in Yi Wan Railway, researches include properties,formation mechanism,risk control and comprehensive treatment of super karst water bursting in deeply buried and concealed karst caverns with high pressure and rich water are carried out systematically and deeply. The main contents and results of researches in this paper are as follow:Through analyzing the situation and characteristics of all previous water bursting in Maluqing Tunnel, a special water burst accoMPanied with high pressure water burst,earth burst and rock burst is defined as super karst water burst; Based on the analysis of super karst water burst disaster, the basic properties of super karst water burst are obtained, and the range of it is defined.②According to the analysis of basic properties of super karst water burst in Maluqing Tunnel, the relationship between probabilities, degree of the supper karst water burst of deeply buried tunnel and the scale of karst water that includes scale of regional karst,scale of karst in signal cavern, zonation of groundwater circulation,groundwater discharge and recharge,deposit in the cavern,the relation between karst morphology and space tunnel is studied systematically and deeply; Law of karst geology that induces super karst water burst and geological original of super karst water burst in deeply buried tunnel are presented. On this basis, the geology factors and forecasting and assessment methods of it which need to be attended specially with the construction of super karst water burst tunnel are presented too.③Through analyzing the mechanical mechanism of super karst water burst and surrounding rock stability of the tunnel when passing cavern closely, simulation for surrounding rock stability of the tunnel passing filling cavern closely is carried out, which reveals the iMPact law of thickness of deposit in the cavern,width of the tunnel and water pressure of the cavern on the surrounding rock stability of karst tunnel and super karst water burst risk. ④Through indentifying the risk factors that led to super karst water burst, the safety evaluation index system for the tunnel with super karst water burst risk is established, and what's more, based on the expert survey, the judge matrix of factors involved in the evaluation and coMParison matrix of each level weight are established, and the weights of each factors is obtained. Based on the fuzzy mathematics theory, safety evaluation model and criteria of comprehensive safety evaluation for the tunnel with super karst water burst is presented, and through assessing the risk of super karst water burst disaster in Maluqing Tunnel, it is indicated that the evaluation model for it is reasonable.⑤For the problem how to reduce the risk of supper karst water burst in tunnel, a technology system—hydraulic energy technology, which is the treatment technology for concealed karst cavern with high pressure and deposit is presented, and the technology that contains water release test,analysis on the cavern,interface locking,drainage system planning,special controlled blasting,forecasting monitoring and the supporting measures is applied in the comprehensive disaster management of super karst water burst in Maluqing Tunnel successfully.