Research On The Mechanism Of Penetrating Grouting In Porous Media Based On The Self-weight Of Slurry

With the continuous depletion of shallow mineral resources,the current mining of mineral resources has gradually entered the stage of mining deep mineral resources from shallow mining,which has also produced a variety of rock and soil problems,such as "three high and one disturbance" problem,surface subsidence,roadway surrounding rock deformation,underground mine seepage water gushing and other problems;at the same time,it will encounter various complex geological structure conditions and mine geological disasters Problems,such as fault fracture zone,loose broken rock and soil mass,soft rock and so on.The engineering practice has proved that grouting reinforcement technology is an effective technical means to solve various geotechnical engineering problems.However,the development of grouting theory lags behind the demand of practical application,which cannot provide effective theoretical guidance for grouting reinforcement in geotechnical engineering.In order to solve the problem that the influence of slurry weight,grouting pipe angle and slurry diffusion direction on the seepage and diffusion process of grouting slurry is not considered in the current seepage grouting research,this paper adopts the research methods of literature research,theoretical analysis,deduction and numerical simulation to carry out the research on seepage grouting mechanism of porous media based on slurry gravity.The main achievements of this paper are as follows:(1)Considering the self-gravity of slurry,the angle of grouting pipe and the diffusion direction of slurry,the seepage motion equations of Bingham fluid,Powerlaw fluid and Newtonian fluid,and the diffusion model of spherical seepage grouting based on the self-gravity of slurry are derived.The method to determine the parameters of the model and the applicable scope of the formula are given.The mechanism of seepage grouting in porous media based on the self-gravity of slurry is proposed;(2)The seepage grouting mechanism of porous media based on the self-gravity of slurry is verified by a practical case.The verification results show that: the change trend of the theoretical calculation results of the slurry diffusion radius considering the slurry gravity is basically consistent with the model test results,and the slurry diffusion morphology considering the slurry self-gravity is basically consistent with that of the model test slurry,both of which are in the "quasi ellipsoid" shape;while the slurry diffusion radius without considering the slurry gravity is equal in all directions,which is a standard sphere And with the different angle of grouting pipe,the diffusion distance of slurry in different diffusion directions is also different,which shows that the angle of grouting pipe and the direction of slurry diffusion also have influence on the diffusion distance of slurry;(3)Based on COMSOL Multiphysics software and Darcy's law,a threedimensional numerical simulation program for seepage grouting mechanism of porous media considering the self-gravity of slurry is developed by using computer programming language technology and relying on the platform of multi physical field coupling software COMSOL Multiphysics and Darcy's law.The program can simulate the diffusion process of Bingham fluid,Power-law fluid and Newtonian fluid in porous media;(4)The results of numerical simulation show that: after considering the selfgravity of slurry,the simulation results of slurry diffusion morphology show "ellipsoid like" shape,which is consistent with the theoretical calculation results and model test results considering the slurry weight;while the simulation results without considering the slurry gravity are consistent with the theoretical calculation results,and the slurry diffusion morphology is a standard sphere;(5)At different grouting pressures,with the increase of grouting pressure,the influence of slurry gravity on the diffusion distance of Newtonian fluid and Bingham fluid gradually weakens,while the influence of slurry weight on the diffusion process of Power-law fluid is opposite.Therefore,for Bingham fluid and Newtonian fluid,the influence of slurry gravity should be considered when using low-pressure grouting;for Power-law fluid,when the grouting pressure is large,the influence of slurry gravity should be considered.