Dynamic Response Analysis Of Fault And Nonlinear Inrush From The Water-Resisting Floor

In the mining activities,the mining safety in China is vulnerable to water invasion due to the combined effect of the mining pressure and the confined water on the seam floor.The process of confined water bursting into the mining face through inrush channel involves the flow of fluids in various structures such as porous media,broken rock masses,rough cracks and re-cemented zones,fault fracture zones.In this paper,floor water invasion was selected as the research background.The whole process of water invasion coupled nonlinearity and the fault dynamic response process in the entire invasion path of aquifer-fault-rough fissure-mining face for the floor water under the combined effect of underground pressure and water pressure.Including the flow process in porous media,rough fissures and broken rock masses were examined using theoretical analysis,numerical analysis and experimental method.An in-depth discussion and systematic study were performed for the coupled flow process in different locations and at different timing during the interconnecting process of individual structures.Ultimately,dynamic response and nonlinear flow characteristics under the combined effect of various structures were obtained,which will be referential for the pre-invasion prevention and the post-invasion control.This paper has achieved the following innovations:(1)Zoning distribution patterns of floor pore water pressure under the water-rock-stress effect.The zoning and layering distribution characteristics of water pressure on the seam floor under the combined effect of water pressure and underground pressure were examined using theoretical solution and numerical simulation.The separation characteristics of the underground pressure "screening" effect caused by changes in rock permeability due to underground pressure under the coupling effect for the distribution of pore water pressure were determined.The simulation results were verified with reference to the measurement data of the floor pore water pressure during the mining process.These research results are important for hazard levels,prevention and control of the floor water pressure distribution.(2)Flow patterns of gravel deposits.With a view to the seepage of broken rock masses in fault fracture zones,the digital imaging based "max.-mini.particle size approximation" was proposed here,a 3D numerical analysis model was established.The variation patterns of seepage velocity field,stress distribution and flow rate as to the fluids in gravels were obtained.The experimental data was verified with "deformation and seepage experiment machine for broken rocks".Results show that the numerical simulation model controls the errors within 10%,the seepage patterns in broken rock masses are consistent with Non-Darcy Forchheimer flow law,which in turn verifies the proposed method to be reasonable and will be referential for the nonlinear flow process studies of fault fracture zones.(3)Mining dynamic response of the fault system.The dynamic response process of the multi-fault system was simulated according to Pandas nonlinear finite element method.The dynamic characteristics and evolution process of the multi-fault system were simulated with adaptive static-dynamic algorithm,and the dynamic response study of the multi-fault system was performed via re-cemented rock masses under the experiment conditions.In the course of the simulation,different dynamic phenomena such as adhesion and slip state on the fault contact surfaces and the state changes among them were considered.The dynamic analysis of the fault system,the multi-field coupling analysis and evaluation were completed.According to the strength of relationship between the mechanical properties of rock materials and the nature of fault contact surface,the fault activation sequence and the conduction path were analyzed and predicted,the failure-activation-movement mechanism of the fault was revealed.(4)Spatial and temporal evolution process of the entire floor water invasion path.In order to reveal the transfer coupling patterns of confined water on individual structures at different timing under the fluid-solid coupling effect in the entire floor water invasion path.The Darcy-Non-Darcy flow equation for the aquifer-fault fracture zone-floor rough fissure zone and for the four stages of the mining face before and after the fault conduction was established.The invasion and flow mechanism of confined water under the stress-water pressure effect was obtained.Results show that the flow patterns vary significantly from one structure to another structure,the fluid-solid coupling effect has a great influence on the Non-Darcy flow characteristics in the fault.As a joint between the aquifer and the mining face,drastic changes in its permeability is the origin of the fault invasion.