Study on the Dynamic Mechanical Properties of Deep-Seated Rocks Under Coupled Confining Pressure and Loading Rate

Deep rock engineering faces the combined challenges of high in situ stress and dynamic disturbances. However, traditional constitutive models treat confining pressure and rate effects independently, leading to significant prediction errors under high confinement, and the underlying coupled mechanisms remain insufficiently understood. To address this, dynamic tests were conducted using an active confining pressure SHPB system under hydrostatic pressures of 0–30 MPa and loading rates of 2000–12,000 GPa·s−1, with simultaneous acoustic emission and dissipated energy monitoring. A confining pressure-sensitive rate-dependent dual-scalar damage constitutive model was established, innovatively incorporating a Constraint Intensification Factor (CIF) and a viscous regularization technique to intrinsically couple confinement and rate effects. The results reveal a synergistic strengthening effect between confining pressure and loading rate, with higher confining pressure enhancing rate sensitivity. The proposed model accurately captures the elastic, peak, and post-peak segments of stress–strain curves, with peak stress errors below 5%, effectively overcoming the prediction deficiencies of traditional models under high confining pressures. These findings provide critical parameters and a reliable theoretical basis for deep rock engineering design.