Research And Development Of Sealing Material For Karst Pipeline Water Inflow And Its Diffusion Law

With the continuous development of economy and society,the construction scale of tunnels and other underground projects in China is expanding,and the number of construction is increasing.Because China is the country with the largest karst area and the widest distribution in the world,it often passes through karst geology in engineering construction,which is easy to induce adverse geological disasters such as water inrush,mud inrush and collapse,and poses a great threat to engineering construction.Among the many adverse geological disasters,the water inrush disaster in karst area causes the greatest loss to underground engineering construction,so it is necessary to carry out relevant research on the treatment of water inrush disaster in Karst pipeline.In this paper,a new grouting plugging material(WIS-2 material for short)is developed according to the characteristics of water inrush,and the grouting diffusion law of wis-2 is studied through the visualized karst pipeline grouting simulation test.With the help of COMSOL multiphysics software,the diffusion pattern of wis-2 grouting material in Karst pipeline is simulated,and the velocity field of simulation test is compared and verified.The main research results are as follows:(1)A new type of expanded crosslinking slurry(WIS-2)with a water absorption response ratio of 170 times was developed.The non covalent weak interaction was used to improve the surface properties of the expanded matrix material,and the improvement rule of the content of natural polymer solution on the performance of the matrix material was studied to obtain the optimal response rate of the modified matrix material;A crosslinking curing agent(CCA)was synthesized and blended with modified matrix materials with different particle sizes.On the premise of meeting the injectability,the material was macroscopically tested and microscopically characterized by laboratory tests.The optimum ratio of the material was determined to be 1:1,and a new grouting plugging material for Karst pipeline water gushing was developed.This material realizes the cross-linking between the material particles,increases the adhesive force with the inner wall of the pipeline after water response curing,improves the ability of resisting dynamic water erosion and the efficiency of dynamic water plugging,and can adjust the slurry particle size to control the response rate,so as to realize the rapid plugging of Karst pipeline water gushing.(2)A visualized karst straight pipe grouting model is built.The influence of pipe diameter,flowing water velocity and grouting velocity on slurry diffusion distance and plugging body length under three particle size distributions is studied by orthogonal test.It is found that flowing water velocity is the main factor influencing slurry diffusion law,and the influence of slurry water velocity ratio on slurry diffusion law is further studied;Based on the orthogonal test,the variation characteristics of pressure field and velocity field in the process of grouting are studied;the anti piston sliding ability of grouting plugging body is analyzed,which proves that the material can still resist the hydrostatic pressure generated by upstream water level after plugging the pipeline.(3)According to the rheological experiment,the slurry flow pattern of WIS-2 material is determined.Considering the time-varying law of slurry viscosity in the migration process,the viscosity time-varying equation is established.On this basis,the temporal and spatial distribution law of viscosity in the grouting process is studied,and the dynamic process of diffusion and migration of WIS-2 grouting material in the pipeline is analyzed;Through COMSOL multiphysics numerical software,the variation characteristics of slurry diffusion shape with time under different grouting rate,pipe diameter and slurry particle size are simulated.Based on the model,the variation law of velocity field in the simulation test is compared and analyzed,the plugging mechanism is revealed,and the rationality of the test law is verified.