| The construction difficulty of underground projects such as tunnels has been extremely challenging.Water Inrush is one of the key factors restrricting the safety construction of tunnels.Long-distance and large-buried depths have become the new features of underground caverns in the future.Therefore,it is of great scientific value and practical value to study the prediction of extra-long and deep-buried tunnel inrush water disasters.Th is paper analyzes the impact mechanism of water inrush disasters by counting 95 cases of tunnel water inrush disaster.On the basis of the above,in view of the disaster-preven ting environment of the water inrush disaster in the extra-long and deep-buried tunnel,combined with the disaster-causing factors of the inrush water disaster,the fuzzy analytic method was used to establish an evaluation index system and method for the risk rating of water inrush disaster in the extra-long and deep-buried tunnels.A complex three-dimensional geological model was established for the high-risk sections in the risk assessment results,and the calculation of the water inrush volume during tunnel excavation was carried out by usi.ng Arcgis and FLAC3D.A method for pre-jrudge the location of the water inrush disaster in the extra-long and deep-buried tunnels,evaluate the risk of water inrush disasters,and quantitative prediction rthe water inrush volume was proposed.The fol.lowing research results were obtained:(1)This study examines 95 cases of water inrush from tunnels.The results are as follows:extra-long tunnels are involved in 72%of the cases,deep tunnels are involved in 53%of the cases,soluble rocks are involved in 84.2%of the cases,and non-soluble rocks are involved in 15.8%of the cases.The water sources of the water inrush are divided into the pilot water source and the recharge water source:the pilot water source is the water storage in the disaster-causing structure.the recharge water source includes the surface water system and the rainfall.The supplementary water source in the same situation,the shallow tunnel the influence of is greater than that of deep tunnels,and the karst area is larger than non-karst area.The range of water inrush with the largest proportion among the pilot water sources the caves and the underground rivers class is one order of magnitude higher than that of the fault and the fissure.(2)Selected 7 indicators suitable for the evaluation of the risk level of extra-long and deep-buried tunnels,built an indicator system,and established a method for evaluating the risk level of water inrush disasters.The prediction the range of the water inrush volume corresponding to the hazard level is given.The proposed treatment and prevention measures are proposed for the hazard level.The application results in Qinling water conveyance tunnel of the Hanjiang to Weihe project indicate that the risk assessment results of the excavation section(about 70 km)are consistent with the actual water inrush,which verifies the reliability of the method.The risk of non-through(about 12 km)water inrush in the Qinling tunnel was evaluated,which laid a foundation for effective prevention of water inrush disasters.(3)Numerical calculation of the amount of water in the high-risk section K15+500~16+900 during excavation,the total water inflow is 165900 m3/d,and the average water inflow per unit length is 1185 m3/d.When the tunnel is excavated to fault fracture zone,the amount of water in the tunnel suddenly increased.The numerical results compared with the feedback on the construction site,the absolute value of the error is between 8.65%and 49.3%.The simulation accuracy of the method meets the accuracy requirements of the water inrush calculation in the project.The main advantage is that the amount of water inflow during the excavation process can be calculated,which can further guide the treatment and prevention measures during the construction process. |
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