Water Inrush Mechanism On Seepage And Stress Coupling Damage Of Coal Floor Under Water Pressure And Its Engineering Application

In resent years, with the increase of mining depth in the Dongjiahe coal mine, the miningenvironment is becoming more complex, the ground stress and water pressure are increasingconstantly, the coal mining under the threat of ordovician limestone water has beenoutstanding in the lower Taiyuan Formation, it is very imminent and important how toefficiently prevent and control water disaster problem of ordovician limestone karst. Thisthesis centres on the influenced factors that affected floor water irruption, establishment ofmathematical mechanical model coupling seepage field and stress field, establishment offluid-solid coupling numerical model, the distribution of mine karst water inrush danger zonefrom floor and design consideration of floor gronting reforming engineering. Throughcomprehensive use of theoretical analysis, numerical simulation, in-situ test and laboratorytesting, a systematic research were carried out about the influence of seepage and stresscoupling on mining failure features and water inrush mechanism of seam floor, and the mainwork is as follow:(1) On the base of engineering geological and hydrogeological and the previous inrushdata of Dongjiahe coal mine, the influenced factors that affected floor water irruption hasbeen studied systematically in No.5coal of Dongjiahe coal mine, including head pressure andthe water abundance of Ordovician limestone, floor aquifuge lithologic, rock assemblagecharacteristics, geological structure and ground pressure and so on. The reasons for floorwater invasion of No.5coal of Dongjiahe coal mine is founded on the interactive effect ofthese factors, Including dominant factors which includes geological structure and headpressure, the subjective factors which includes the water abundance and rock assemblagecharacteristics, the promotion factors which includes ground pressure, the subjective factorswhich includes the inclined length and mining area of the coal face. (2) According to the theory of elastic mechanics and face underground pressure theory,established the ideal linear elastic-plastic softening constitutive model of coal, expressions oflead abutment pressure ahead of the working face is derived, and combines with stressanalysis of semi-infinite plate body under vertical loads, it reveals basic characteristics ofstress distribution of the coal floor, also the yield line of stress over seam floors betweenpre-and post full mining are given by yield condition. At the same time, the mining failureform and floor-broken depth were given using the theory of slip line field. By above research,then enriches and consummates water inrush theory theory and technology of coal seam floor,it is laying a solid foundation for theoretical research on groundwater hazard preventiontechnique of No.5coal of Dongjiahe coal mine.(3) By using the method of theoretical analysis, the paper is the mutual combination oftheoretical study and site measurement, based on field test research of mining distortion andfailure character of coal seam floor, the evolutional regularity of mining destruction and themaximal failure depth for No.5coal of Dongjiahe coal mine have been basically grasped, thekey technological problems of field measurement is realized by theoretical method.(4) By using of the software of the coupling system of flow and solid in rock failureprocess anslysis(F-RFPA2D), the bottom board structure for No.5coal of Dongjiahe coal mineis established based on coupling of seepage field and stress field, the numerical simulationwas conducted for the influence of mining and seepage, the change law of mining failurefeatures and percolation characteristics of seam floor aquifuge and is revealed, which providesthe scientific basis that will be helpful to the further study for floor faultage’s water regularitymining on the top of water pressured.(5) Combined with actual hydrogeologic conditions, the destruction depth of floormining that is consideredwhether or not are analyzed and the danger zones of water inrushfrom floor aquifuge of No.5coal of Dongjiahe coal mine are predicted using the way of waterbursting coefficient, and then the water resisting property of the floor stratais also evaluated,and predicting water inrushes situation of the floor under the circumstances of coal mining infuture, In order to liberation coal reserves of the ordovician limestone water disaster threatfurthest in No.5coal of Dongjiahe coal mine, these coal reserves of5344.6million tons isattained, its result improves the recovery rate of Dongjiahe coal mine resources, and createsthe considerable economic efficiency. This study laid a foundation for coal mine water hazardprotection and control of Dongjiahe coal mine.(6) Through the systematic researching from the article, and applying researches allabove to the grouting reinforcement project of floor aquifer in No.22507working face of No.5coal in Dongjiahe coal mine, the fluid-solid coupling numerical analysis method is usedfor water disaster control practice, and grouting reinforcement strengthening and rebuildingtechnical method based on simulated output was put forward, safety mining of No.22507coalmining face has been realized at present, which have achieved enormous economic benefitsand social benefits. These research results have provided the reference experience that will behelpful to the further prediction and prevention for floor water disaster of ordovician karstmining on the top of water pressured in Dongjiahe coal mine and even all over Chen-he coalmine area.