In order to study the dynamic mechanical properties of coal-rock mass in gateway floor of im-pact-prone coal seam,the impact compression tests of cylindrical coal-rock combined specimens(CRCS)under dynamic and static loads are carried out with the coal samples and floor rock samples from the gateway at fully mechanized caving face of Gengcun Coal Mine by the split Hopkinson pressure bar(SHPB)test system.The effects of coal-rock combination ratios,impact velocities,and confining pressures on the dynamic mechanical properties of CRCS are studied.The test results show that the im-pact compression deformation process of CRCS can be divided into four stages according to the dynamic stress-strain curves.Several yield platforms appear in the deformation of CRCS during their yield stages.The dynamic compressive strength and yield strengths of CRCS have a exponential negative correlation with the coal-rock combination ratios.The dynamic peak strength,deformation modulus and ultimate strain of CRCS have a positive linear correlation with impact velocities.The dynamic peak strain,ulti-mate strain and residual strain are negatively correlated with confining pressures.Based on the statistical damage theory,the viscoelastic aging damage constitutive relationship of CRCS under three-dimensional and medium strain rates is established.The fitting degree between the theoretical and the experimental curves is so high that theoretical curves can be used to represent the stress-strain relationship of CRCS under triaxial impact compression.The conclusions provide a theoretical support for the study of deform-ation and instability mechanism of CRCS during deep mining in coal bump mines.
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