Research On Mechanism And Prevention Technology Of Water-rich Fault Permeation Disaster In Deeply Buried High-speed Railway Tunnel

Aiming at the potential hidden danger of seepage water inrush disaster when the Fuzhou-Xiamen cross-sea high-speed railway tunnel passes through the water-rich fault,this paper aims to study the disaster prevention and control of the fault zone of Bifeng temple Tunnel,and conducts research on the mechanism and prevention technology of seepage water inrush disaster in fault zone.The following innovative results have been achieved:(1)Based on the fractal similarity theory and the non-Darcy seepage theory,the nonlinear seepage disaster evolution mechanism of water-rich fault is revealed,which lays a foundation for the research on disaster prevention and control measures for construction through water-rich fault zone.Based on the fractal similarity theory,the triaxial permeability test of tuff in fault zone was carried out,and the nonlinear permeability law,pore structure instability evolution mechanism and seepage velocity time-varying law of tuff in fault zone with different particle gradations were obtained,and then the nonlinear permeability instability evolution mechanism and discriminant method of tuff in fault zone under different pore pressure gradients were obtained.On this basis,combined with the seepage-stress coupling numerical simulation test,the influence of nonlinear seepage instability and flow transition mechanism of the fault zone in engineering disasters is clarified,which provides a theoretical basis for the prevention and control measures of subsequent tunnel engineering crossing water-rich fault zone.(2)Based on the nonlinear cusp catastrophe theory and numerical simulation,the critical criterion for the excavation of water-rich fault tunnels is established,which provides a theoretical basis for the prevention and control of water-rich fault tunnel construction disasters.Based on the cusp catastrophe theory and the structural mechanics model,the critical criterion for the catastrophe of the catastrophic structural rock mass between the Bifeng temple high-speed railway tunnel and the water-rich fault zone in front is deduced,and the key influencing factors affecting the critical distance of the catastrophe are obtained.The applicability and rationality of the obtained criterion are verified by field application.Combined with the three-dimensional finite difference numerical model test,the fluid-solid coupling fracture mechanism of the catastrophic rock mass under the influence of excavation disturbance is obtained,which further supports the accuracy of the criterion derived based on the cusp catastrophe theory.(3)The disaster characteristics and disaster prediction method of tunnel crossing water-rich fault were explored,and preventive measures such as"advance zone hydrophobic curtain grouting,three-step temporary inverted arch method,and composite lining" were proposed to avoid water inrush disasters and landslide accidents.Aiming at the technical problems of preventing and controlling the water inrush accident of the newly built long high-speed railway tunnel crossing the water-rich fault zone that has not been effectively solved at home and abroad,combined with the previous conclusions and achievements of the systematic research on the water-rich fault zone and the catastrophic rock mass,successively put forward Different from the current traditional methods,the post-disaster zoning treatment technical measures and pre-disaster comprehensive prevention technical measures for water inrush and landslides in the water-rich fault zone are presented.Through the practical application and effect analysis and evaluation of the Bifeng temple tunnel project,the preventive measures of "the occurrence characteristics of the water-rich fault zone and the prediction and identification system of the disaster-pregnant fault zone,the grouting of the hydrophobic curtain in the advanced zone,the three-step temporary invert method,and the composite lining" have been verified.Therefore,it provides a guarantee for the successful completion of the subsequent Bifeng temple tunnel construction,and also provides a valuable scientific reference for the tunnel construction in similar geological environments.