Numerical Simulation On Grouting In Fault Fracturezone Based On COMSOL Multiphysics

Fault,one of the main triggering factors forming water bursting,not only can make mining hydrogeological conditions complex,but also may reduce the stability of engineering rocks.Therein,fault rupture zones tend to become a route for underground water storage and migration.Fs866 Fault,which is a boundary fault with 2412-meter extension length and fault throw ranging from 25m to 60mlocated in West II Mining Area at Zhangji Colliery,poses a serious threat to the safe mining of 1413 first coal mining face in Coal Group A.In order to guarantee the safe mining,the grouting transformation measure was taken on Fs866 fault zone based on the comprehensive analysis of mining hydrogeological conditions in Group A.In order to verify the grouting effect,grouting objects(namely fault zone and influence zone)were regarded as "channel-fracture"double medium in this thesis,and then fault grouting hydrogeological conceptual model was established.Hydrodynamic conditions,high stress,crack and pore water pressure,and grouting pressure existed in the in-situ grouting operations were all taken into consideration using multi-field coupling method.By adopting Comsol Multiphysics software to simulate the slurry migration and diffusion,the dynamic process of slurry infiltration,slurry diffusion,diffusion radius of the grouting hole and the average density of the fracture fluid were analyzed.In addition,drilling water,water temperature,water pressure change,water absorption,geophysical results-Q curve analysis and coring inspection were taken as multivariate indexes to synthetically evaluate routing effects.The results show that:Fs866 fault zone is characterized by water-bearing property water conductivity,therefore grouting reinforcement on the Fs866 fault zone is made in order to avoid the mining-inducing fault activation.Eventually,grouting curtain is formed and the aim of water sealing and reinforcement is achieved.The results demonstrate that the grout is centered around the grouting hole with approximate circle distribution.Besides,a positive correlation is found between diffusion radius and time lapse,while diffusion velocity decreases gradually and eventually tends to zero with time.Grout diffusion range in fault zones is between ranges of fault fracture zone and intact rock layer.The greater fracture develops,the smaller the slurry resistance is,leading to larger diffusion rates and greater diffusion areas.Calculation error of diffusion radius between the simulation result and theoretical analysis is about 10%,indicating that two results basically coincide.The comprehensive single-and multi-factor analysis for grouting in fault zones shows that grouting effect is well,achieving the aim of water sealing and reinforcement,and verifying the correctness of numerical simulation results.The analysis above in this paper hopes to provide a scientific reference for future similar grouting engineering.