Study On Water Inrush Mode Of Mountain Tunnels And Countermeasures For Grouting And Water Restriction

China is a mountainous country.As the road network extends to mountainous areas,highway construction inevitably has to cross various high mountains and mountain tunnels.Mountain tunnels have become more and more extensive.The geological conditions in mountainous areas are complex,and mountain tunnels often need to pass through water-rich areas.The presence of groundwater not only affects the safety of tunnel construction,causes water and mud bursts,but also easily causes a series of ecological and environmental problems.The safety problem of water rich mountain tunnel is particularly prominent.In this paper,with the Chuntianmen super-long tunnel as the engineering background,the numerical simulation analysis is carried out by FLAC（3D）finite difference software,combined with the on-site grouting and water blocking test in the water-rich section of the Chuntianmen tunnel,the water inrush disaster-causing structure and its outburst in the Fushuishanling tunnel Water mode,analysis of countermeasures for grouting and blocking water discharge in the water-rich section of Chuntianmen tunnel,further study on safety control measures of high-pressure water-rich mountain tunnel,and a tunnel water pressure monitoring and early warning system.The main research contents and results of this article are as follows:（1）Summarize and analyze the disaster-causing structure of water-inrush and mud-inrush in water-rich tunnel,and summarize them into five types:fracture zone formed by fracture,water-rich dissolution cavity formed by dissolution,water-rich fracture zone formed by erosion,and fold The formed water-rich syncline,the pipeline and underground river formed by the interconnection of groundwater.（2）The water inrush catastrophe model of the rich water tunnel is summarized into three division methods:the water inrush mode based on the mechanism of damage of the water-proof rock disk,the water inrush mode based on the time when the disaster occurred,and the water inrush mode based on the spatial location of the disaster.（3）The on-site grouting and water blocking test of Chuntianmen water-rich section is analyzed,and it is concluded that the single cement slurry has a long setting time and low strength after setting,and the cement-water glass slurry prepared by the test can effectively overcome the shortcomings of the single slurry,and Applied to the construction process of radial back grouting in tunnel water-rich fault fracture zone.（4）Through the axisymmetric simplified tunnel seepage model,the calculation formula of the water displacement of the water-rich tunnel is derived,and the correlation curve between the grouting ring thickness and the grouting ring permeability coefficient and the tunnel displacement is obtained.（5）Combined with the actual engineering data of Chuntianmen Super Long Tunnel,FLAC（3D）numerical simulation analysis software was used to analyze and simulate different lining restrictions,different grouting ring thicknesses,and different grouting ring permeability coefficients.The numerical simulation analysis shows that the water pressure behind the lining,the tunnel displacement and the thickness of the grouting ring,the ratio of the grouting ring permeability coefficient k₁ and the surrounding rock permeability coefficient k₂ are related,and the displacement of the tunnel from excavation to construction of the second lining.（6）Combining the types of disaster-causing structures and catastrophic models studied previously,a water pressure monitoring and early warning system for high-pressure water-rich tunnels is proposed,and the targeted control measures for water inrush disasters in high-pressure water-rich tunnels under typical disaster-causing structures are summarized.