| During the construction of underground engineering in serious karst area, geologica hazard of water inrush and mud outburst often occur in tunnel and other underground engineerings,which ofter lead to equipment destroyed and construction period bungled,even serious casualty and economic loss.With western development,large scale disaster of water inrush has gradually become the bottleneck problem of underground engineering development.In order to know the passage formation modle and instability mechanism,similar model test,field test,nonlinear catastrophe theory and numerical simulation have been done for the mechanism of water inrush and its prevention measures,and the technical system of water inrush prevention and control has been put forward,consequently series of meaningful research achievements has been obtained.Firstly,according to the analysis results of large scale disasters of water inrush,the occurrence conditions has been put forward from the view of energy storage of water bearing structure,dynamic zone of karst water and energy release, and system instability of water bearing structure,and influencing factors of water inrush includes geological factors and engineering factor,the microscopic and macroscopic characteristics has been analyzed,the water inrush can be divided into two types induced by geological defects or not.Based on the common characteristics of different water inrush types,the process of water inrush has been divided into energy storge stage and instability stage,the characteristics of fluid state has been simulated by COMSOL for the process of water inrush induced by excavation,numerical results show that the fluid state process of water inrush can be divided into Darcy in the aquifer firstly,Brinkman in the potential passage of water inrush secondly and N-S in the tunnel lastly.For the water inrush induced by instability of key aquifuge,the formation mechanism of water inrush passage and its instability criterion has been studied from microscopic and macroscopic viem.The analytical solution for tunnel stability with the seepage and its instability criterion has beenderived through the elastic-brittle damage model,and damage mechanism induced by seepage and dynamic excavation has been analyzed by the self making language of Flac 3D fish. The catastrophe evolution of water inrush passage has been simulated by RFPA for the crack initiation,propagation,coalescence and passage formation induced by seepage damage,and the catastrophe mechanism of water inrush passage formation for fractured rock mass has been presented from view of the multi-field information evolution;The concept of key aquifuge has been adopted for the water inrush model of deep bueied tunnel of layered limestone,the cusp catastrophe and double-cusp catastrophe model of key aquifuge has been established for static and dynamic instability,and its nonlinear catastrophe characteristics has been futher studied,so the instability criterion and calculation formula for minimum safety thickness of rock mass has been obtained.In addition,numerical simulation has been done in order to know the relationship between safety thickness of rock mass for water inrush preventing and blasting factor,water pressure and so on.Finally, the calculation formula for minimum safety tickness has been proved by the tunnel engineering example of water inrush,and the instability mechanism of key aquifuge induced by sustained coupling effect of seepage and damage evolution combined with the numerical results.Further study has been done by similar model test for water inrush mechanism induced by seepage damage.Based on the analysis on similarity theory of 3D solid-fluid coupling,the new similar material of solid-fluid coupling has been found,and similar model test for water infow of tunnel and water inrush of mining area has been done by self-developed extensible 3D test bench and optical fiber monitoring system,the evolution mechanism of water inflow and water inrush induced by seepage damage has been analyzed by the monitoring results of multi-field information,the simultaneous sudden jump phenomenon of stress, disppacement,seepage pressure and other information has been analyzed,and the macroscopic instability criterion has been proved again,the conclusions have also been proved by numerical results.For the water inrush induced by geological defect,two typical catastrophe models has been put forward according to analysis on seepage properties and classification of different geological defect,and the formation mechanism of water inrush passage and its instability criterion has been studied from microscopic and macroscopic viem.Based on the further analysis on seepage properties difference for geological defect of different scale,the instability mechanism of filling medium induced by seepage effect and water outburst model induced by blocking body of karst conduit has been studied,and the water inrush mechanism of Qiyueshan has been interpreted by the model application induced by karst conduit of filing type during the reainfll period combined with the numerical results;For the water inrush induced by water non-conductive fault,the catastrophe model of swallow tail style has been estabilished considering the mechanical effect of two section filling medium and its seepage properties differences,and corresponding countermeasure has been put forward according to the analysis of modle control parameters.In addition,the catastrophe mechanism of rupture passage induced by fault activation has been further studied by a series of numerical results considing the seepage damage,four types of water inrush evolution passage has been put forward and the analysis on influence parameters sensitivity for water inrush induced by fault has been done.Finaly,based on the water inrush mechanism of different type,compound modle of water inrush has been put forward and its disaster mechanism has been done for the water inrush passage composed of activation fault,karst conduit of filling medium and rock mass preventing water.Finaly,based on the research results of passage information and instability mechanism for different type of water inrush,the technical system of water inrush prevention and control has been established for engineering practice of two high-rish karst tunnel in Hurong highway,and key technology of comprehensive predition and early-warning for geological hazards during tunnel construction in high-rish karst areas has been put forward firstly.Based on guiding principle of this systm,new grouting equipment of high pressure large volume and chemical grouting material has been developed,and lots of field tests have been done in two karst tunnels,such as rsik grade division in Qiyueshan tunnel and Wuchiba tunnel, karst aquifer detection by comprehensive geophysical method and warning maneuven for water inrush disaster in Wuchiba tunnel,grouting treatment of water inrush in Qiyueshan tunnel.The practicality and high effectiveness has been proved by the lots of filed test results and application benefit.
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