Synergistic Bearing Mechanism Of Backfilling Body-support-coal Body In Deep Backfilling Working Face

Backfilling mining with super-high water material has the characteristics of high filling rate,less material consumption and strong adaptability.It is an effective way to realize the safe,efficient and green mining of deep coal seam under the"three under"conditions.However,its effect is mainly affected by the mechanical characteristics of filling body and the bearing structure of filling mining.The collaborative bearing mechanism of filling body support coal body is an urgent difficult scientific problem to be solved in the current green mining of deep coal resources.In order to explore the collaborative bearing relationship among the three,this paper takes the super-high water backfilling working face in deep coal seam of Yineng coal mine as the engineering background,based on the collaborative bearing mechanism of backfilling body support coal body,comprehensively uses the research methods of field investigation,theoretical analysis,numerical simulation,similar simulation,field monitoring,etc.,through the macro mechanics and microstructure test of super-high water consolidation body,obtains the results of backfilling Based on the functional relationship between the strength of backfilling body and time,the macro mechanical characteristics and the micro progressive damage correlation mechanism,the mechanical model of backfilling body-support-coal body cooperative bearing is established,the differential equation of roof deflection in super-high water backfilling face is established,the main factors affecting the cooperative bearing effect of backfilling body-support-coal body are proposed,and the backfilling body-support-coal body cooperative bearing effect in backfilling face is revealed The numerical model of backfill support coal collaborative bearing is established by FLAC^3D software.The parameters of different working faces are simulated and verified by similar simulation.Finally,the reasonable working face parameters are put forward and applied in the field.The main achievements are as follows:(1)The bearing process of the backfilling is divided into five stages:unconsolidated zone,initial setting zone,rapid strength increasing zone,slow strength increasing zone and strength stable zone.Combined with the microscopic characteristics test,it is considered that the ettringite content of the super-high water consolidated body decreases with the increase of water volume ratio,and the internal structure of the material changes from compact to stable It is loose and its strength is reduced.(2)In the mining direction of working face,according to the bearing structure,the bearing area is divided into four parts:coal body support area,support controlled roof area,empty roof area and filling body support area.Through the interaction of backfilling body,support and coal body,the backfilling body-support-coal body collaborative bearing structure is formed among the bearing areas.The factors influencing the bearing structure include coal elastic foundation coefficient,hydraulic support strength and engineering strength Among them,hydraulic support strength,advancing speed of working face and water volume ratio of filling body are the main influencing factors.(3)The numerical simulation verifies the influence of three main factors on the stability of working face,when the advancing speed of the working face is less than1.8m/d,the support strength of the support is higher than 0.64MPa,and the water volume ratio of the filling body is lower than 94.7%,the overburden stress of the working face decreases,the stress concentration factor of the coal body in front of the working face decreases,and the backfilling body reaches the expected support strength The backfilling body-support-coal body synergistic bearing effect is obvious,and the overburden is effectively controlled.(4)The field monitoring data show that the stress of overburden in the working face is reduced,the deformation of roadway in the advance support area is small,the stress concentration coefficient of coal body in front of the working face decreases,the filling body reaches the expected support strength,there is no obvious periodic pressure phenomenon in the working face,the maximum subsidence of the surface is 182mm,the ground breaking level reaches the protection range of class I,which verifies the rationality of the working parameters.In order to realize the deep coal seam The green safe and efficient mining provides scientific basis.There are 70 figures,19 tables and 83 references in this paper.