Basic Study On The Characteristics Of Overburden Strata Movement Under Deep Gague Backfill Mining

The application of gangue filling and coal mining technology to deep mining is an important way to realize the green mining of deep resources,and the overburden migration is controlled by the compressive properties of gangue,the compression deformation of the broken gangue is the primary factor affecting the direct top break,so it is very important to analyze the engineering mechanical properties of the gangue for the study of overburden migration.In this paper,combined with theoretical analysis,indoor experiments,similar material simulation,numerical simulation of a variety of experimental means and methods,the study of deep gangue filling mining overburden characteristics,filling gangue characteristics,compression performance and other related issues.The main conclusions are as follows:(1)Through the theoretical analysis of "equivalent mining height",the sinking amount of overburden is mainly composed of three parts:the sinking amount of the roof before gangue,the amount between gangue and the direct top and the compression amount of the gangue.Combined with the theoretical analysis of elastic foundation beam,the elastic foundation coefficient and the amount between gangue and the direct top are the main factors affecting the sinking of the direct top rock girder,and the maximum sinking value of the lateral rock beam in the filling goaf is(q/kg)+U2;Under the condition of elastic deformation,the supporting pressure is bounded by the coal wall of the working face,the support stress on one side of the coal wall decreases gradually to the original rock stress with the distance from the coal wall,the support pressure on one side of the filling goaf increases gradually to the original rock stress with the distance from the coal wall.(2)Compared with the ideal grade,the large particle size content of the first broken gangue is too much,the content of small particle size is too little,the small particle size of secondary broken gangue is dominant,and the content of large particle size is too low;The method of improved grading is to mix the first broken gangue with equal quality with secondary broken gangue,and the compaction performance of the continuous grade group gangue and the mixed gangue is basically close,which is significantly better than the first broken gangue.(3)The simulation results of similar materials show that the moving deformation mode of the gangue filling layer is mainly curved,fractured and off-layer,and only the fractured belt and bending sinking zone are developed in the overburden rock,and the direct roof fracture does not collapse,and the overburden rock structure is complete.(4)The numerical simulation results show that the support pressure is in the stress raising zone on the side of the working face and the coal wall of the open-cut,the stress release area on the side of the goaf,and the middle of the filling body is restored to the original rock stress after the mining;With the deepening of buried depth,the compressive deformation of gangue filling body will increase,and the greater the relative compaction degree of gangue filling body,the moving deformation of the roof will increase;The relative compaction degree of gangue in the improved grading group is less than the first broken gangue,the compression deformation of the gangue is small,and the intensity of the pressure appears decreases.