Experimental study on dynamic mechanical properties of sandstone under different impact strength

To reveal the influence of impact strength on dynamic mechanical properties of rock, dynamic failure tests of sandstone under different impact strength are carried out with the modified Hopkinson pressure bar (SHPB) device, and dynamic stress-strain curve and stress waveform are measured.Then, the influence of impact strength on sandstone strength, strain characteristics and energy dissipation are analyzed based on experimental data.The results show that the dynamic stress-strain curve directly enters the elastic deformation stage without a compression stage, and the greater the impact strength, the longer the stress-strain path.The impacted rock samples include fracture and fragmentation, and the degree of fragmentation is positively correlated with the impact strength.Besides, average dynamic compressive strength and average failure strain both increase linearly with increasing impact strength while the average strain rate and impact strength increase in accordance with an exponential function.The larger the impact intensity is, the higher the incident energy and reflection energy are while the transmission energy does not change obviously.The transmission coefficient and reflection coefficient respectively increase in power function and decrease in logarithm, and the absorption energy respectively increase exponential and logarithmic with impact strength and average compressive strength.The conclusions show that different impact strength has a significant influence on strain characteristics, strength characteristics and energy dissipation of sandstone.