Experimental investigation on dynamic compressive mechanical properties of weathered granite and statistical damage constitutive model

This study investigates the dynamic mechanical properties of weathered granite under high strain rates using dynamic compression tests conducted with the Split Hopkinson Pressure Bar (SHPB) method. The objective is to comprehensively understand the behavior of weathered granite, including its failure mechanisms and energy dissipation characteristics. The test results show that the dynamic compression strength of weathered granite increases from 87.95 MPa to 192.51 MPa, as the strain rate is increased from 43.69 s(-1) to 137.08 s(-1), the dynamic strength increase factor (DIF) has a linear relationship with the strain rate. The obtained dynamic stress-strain curves during impact loading exhibit distinct stages, namely elastic behavior, crack expansion, and plastic deformation up to failure. Cracks propagate directionally along the principal stress direction, resulting in tensile failure and progressive fracture from edges to interior. Furthermore, the absorption energy, transmission energy, and reflection energy of weathered granite samples exhibit distinct relationships with incident energy, following linear, logarithmic, and quadratic patterns, respectively. The extent of fracture significantly affects important parameters such as wave impedance, reflection coefficient, and transmission coefficient. Using energy theory and statistical damage theory, a dynamic statistical damage constitutive model for weathered granite was developed. The model was validated by comparing the theoretical results with the test curves. The obtained results contribute valuable insights into the dynamic mechanical properties and constitutive model of subsea rock, providing theoretical support for marine engineering construction.