Experimental research on the dynamic tensile fracture and the energy dissipation characteristics of coal-serial sandstone

The surrounding rock is in a high-stress disturbed environment in the process of deep mining. A detailed study on the tensile mechanical properties of rock under dynamic loading is an important foundation for the effective control of the stability of surrounding rock and safe production. Dynamic Brazilian disc tests on coal roof sandstone were performed through Hopkinson pressure bar (SHPB) test system. The following conclusions can be drawn:the dy- namic tensile strength of sandstone gradually increases as the loading rate increases,which is more significant at higher loading rates;the dynamic tensile failure of sandstone can be divided into three stages:the generation of main crack, the development of micro-crack and crack penetration;under the influence of increasing loading rate,the failure mode of the specimen gradually develops from the single tensile failure to the coexistence between tensile failure and local shear failure with decreasing average fragment size and more obvious deterioration;in addition,the dissipated energy required by the failure of the specimen increases with the increasing loading rate,and the proportion of input energy gradually augments,that is,the energy utilization rate of sandstone gradually increases.