Research On Water Inrush From Floor Laws Of Coal Working Face In Xingdong Coal Mine

Coal is important energy foundation of our country’s economic and social development.With the increase of mining depth and the degradation of mining conditions,the problem of coal mining receive water inrush is more and more serious,so the research on the rules of the occurrence and development of water inrush from floor is significant.Firstly this paper according to the engineering practice of water inrush from floor,complete floor strata is simplified to the elastic-plastic sheet and using the principle of minimum potential energy of bending of thin plate analyzes the characteristic of stress distributed after mining and failure law of water inrush from floor.Taking one working face of Xingdong mine as engineering background to conduct similar material simulation experiment,by the analysis results of geological data determine the actual rock lithology parameters;According to similarity principle,combined with test bed size to determine geometric,time and stress scale and heap physical model.Independent design pressure device simulate the effect of confined water,through real-time monitoring data of displacement measuring point and pressure cell reach the law of deformation and fracture of coal seam floor and pressure change of stope.Adopt numerical simulation method to study vertical displacement,stress and plastic zone distribution of floor in the process of mining,and compare with the results of mechanical model analysis and similar material simulation,reach the law of water inrush from floor of mining working face and hereby put forward preventing measures.In this paper,we obtain the following results:(1)Hypothesis complete floor strata for the four sides clamped rectangular thin plate,reach that at the midpoint of the solid supported edge have the largest bending moment,that is to say the floor strata most easily broken in the middle of working face,and through the elastic theory reach the limitation water pressure that the floor strata can bear,which is connected with floor thickness,the size of the working face and shear strength,poisson’s ratio and other physical and mechanical properties of rock stratum;(2)In front of the coal wall appears stress concentration after coal mining that decreasing with bottom depth increasing.Goaf appear floor heave phenomenon,with the increasing of depth deformation curve of floor heave from "tall-thin type" to "short-fat type" conversion,at the same time floor produce separation;(3)In the horizontal direction floor deformation can be divided into advanced compression stage,release expansion stage,compression stability stage.Floor stress experience"stress of primary rock-stress concentration-stress release-gradually compaction-restore stress of primary rock"changing process;(4)The floor strata on both sides of coal wall prone to occur shear failure which make the effective thickness of water-resisting layer decrease.At the coal mining preliminary stage,maximum floor heave,maximum bending moment and the vertical cracks occurred in the middle of the goaf,which is gradually move to central-forward direction of goaf with the increase of mining,this place is danger area of water inrush from floor;(5)Aim at practical situation of the working face and combination with the results of the study put forward that use strip filling method to prevent water inrush from floor,and through theoretical analysis and numerical simulation verify the feasibility of the measure.