Study on Dynamic Behavior and Energy Dissipation of Rock considering Initial Damage Effect

To explore the influence of initial damage on the dynamic characteristics of rock mass, the Φ 50 mm split Hopkinson pressure bar (SHPB) test system was used, and the uniaxial impact compression tests on yellow sandstone specimens with different damage degrees were conducted, and then the variation law of mechanical properties of rock specimens with the initial damage was determined. The test results show that the dynamic stress-strain curve of rock specimens with initial damage can be roughly divided into compaction stage, elastic deformation stage, crack evolution stage, and strain-softening stage; the higher the initial damage degree of rock mass, the more significant the compaction stage. With the increase of the initial damage degree, the dynamic elastic modulus and peak stress of rock mass decrease gradually in a power number, while the peak strain of rock mass increases exponentially. With the increase of the initial damage degree, both the reflected energy ratio and the dissipated energy ratio decrease linearly, while the transmitted energy ratio increases linearly; the increasing rate of the transmitted energy ratio is greater than the decreasing rate of the reflected energy ratio.