Mechanism Of Shallow Water System Stability Control And Mine Area Planning Principle In Northwest Coalfields

The stability of shallow water system,as the pivotal maintaining eco-system equilibrium and facilitating sustainable development of mine sites,is the core of various dynamic indicators in response to mining activity and of mining area planning.It is of great significance to proceed in-depth studies on the mechanism of shallow water control and principle of mining area planning,which is conducive to improving the integrity,orderliness,systematicness,and scientificity of coal resource exploitation in Northwest China.Based on the damage and seepage characteristics of soils and overburden strata,this thesis refines the method for calculating the equivalent permeability coefficient of overburden strata,constructs a quantitative model for assessing shallow water system stability,and proposes the principle of mining area planning by dynamic programming means,mainly obtaining the following results:(1)Reveal the mechanism of rock damage and seepage evolution due to mining.Propose a method to characterize anisotropic rock damage from both macroscopic and mesoscopic perspectives;reveal the intrinsic mechanism of anisotropy and fracture morphology affecting permeability;develop a constitutive model describing stress-seepage-damage behavior of anisotropic rocks,quantity the permeability variation of rock/soil strata with damage of different degrees.Propose a numerical method for overburden strata permeability characterization;achieve the dynamic update of strata permeability profile with mining operation progressing.(2)Propose a method for strata equivalent permeability coefficient(EPC)determination.Develop a numerical method for calculating the degree of strata damage induced by mining;reveal the mutual feedback relationship of the maximum damage with mining height and horizon of rock/soil layer;analyze the water-conducting property of fractures with different types;develop an EPC calculation method dominated by rupture and damage models;reveal the time-spatial evolution characteristics of EPC via an improved dynamic model representing overburden strata deformation and 3D permeability variation.(3)Elaborate the response of shallow water system to mining and the control mechanism.Propose a numerical approach for EPC processing;construct shallow water flow models considering lateral recharge,infiltration recharge,and multi-unit circumstance;reveal the characteristics of shallow water response to various mining units;discuss the impact of mining height,distance between coal seam and overlying water,time of recovery,and mining scope on shallow water system stability;elaborate the effect of multi-mine disturbance on shallow water system.(4)Propose the principle of mining area planning constrained by shallow water system stabilization.Put forward a method for assessing the stability of shallow water at mine sites;achieve the zoning of shallow water system stability in response to different mining intensity in the case area;innovate a layout method considering multi mines and scientific productivity based on dynamic planning and optimized model;taking Yushen area as a case,construct a novel pattern of mine layout based on shallow water system stabilization;quantify the configuration scheme of coal mines with representative geological settings;identify the mine planning principle constrained by shallow water stability maintenance via dynamic programming means.The thesis includes 185 figures,53 tables,and 251 references.