Study On Coupling Mechanism Between Gangue And Surrounding Rock Under Filling And Mining Condition

The filling material of gangue is a kind of discontinuous medium.Under the loading action of overlying rock,the effects of mutual rubbing,rotation,crushing,filling and consolidation will occur during the compression of gangue blocks.The compaction deformation characteristics of gangue are affected by gangue lithology,different grain size ratio and different spatial distribution,etc.By studying the compaction deformation characteristics and mechanical behavior of gangue filling,a theoretical basis is provided for controlling rock strata movement mechanism.Based on the factors affecting the compaction deformation behavior of gangue backfill,this paper makes a homemade gangue particles with different grain sizes and their gradation and loads them.Then obtains the load-deformation relationship of gangue particles with different grain sizes by means of laboratory test,theoretical analysis and numerical simulation.The particle flow method is used to analyze the deformation process of filling gangue and the evolution characteristics of the force chain between the filling gangue.Based on the loading behavior of gangue,a physical similar material simulation model of stope roof and floor under the control of gangue filling material was established,and the law of overburden ore pressure under backfill control is revealed.The main research contents are as follows:(1)The physical properties and basic mechanical properties of gangue with different grain sizes were tested by screening gangue blocks,and the mechanism of gangue compression process was obtained according to the load-deformation relationship of different grain sizes.(2)By writing the PFC program,the mechanical curve of the compaction stage in the calibration process is developed.The numerical analysis model of granular mesoscopic action is established to obtain the mechanical action process of gangue blocks in the compaction process,the evolution characteristics of granular structure and morphology are deeply analyzed,and the microscopic action mechanism of the compressive behavior of gangue filling materials is revealed.(3)The simulation test of physical similar materials was carried out with the help of similarity theory,and the failure and slippage of overlying strata in goaf were compared between caving method and filling method as well as the backfill with different stiffness in the mining process,and the floor stress evolution law was revealed under different filling and mining conditions.(4)The relationship between backfill and surrounding rock plastic zone radius and surrounding rock elastic plastic deformation is analyzed by establishing the model diagram of surrounding rock elastic plastic zone.Meanwhile,the method of "finding points and making lines" is put forward to realize accurate filling,and the technical application of "roof-backfill-floor" is discussed.