Dynamic mechanical properties and energy analysis of argillaceous siltstone and quartzite under impact loading

To explore the dynamic mechanical properties and energy dissipation characteristics of different rock types under impact loading, critical for deep tunnel engineering, dynamic compression tests were performed on argillaceous siltstone and quartzite using a Split-Hopkinson Pressure Bar (SHPB) device, under various strain rates and stress conditions, along with finite element simulations in LS-DYNA, employing the RHT constitutive model, to delve deeper into the failure mechanisms of rocks under various stress states. Unlike prior studies, this research integrates true triaxial conditions to reflect complex in-situ stresses. The results show that as the strain rate increases, the peak strength of both rock types significantly increases, and the failure mode shifts from block failure to powder-like failure, with energy exhibiting an upward trend. The increase in incident and transmitted energy was more substantial than that in reflected and dissipated energy. At a strain rate exceeding 75 s⁻¹, under non-confined conditions, the incident energy of the two rock types increases by 94.90 % and 130.4 %, respectively, and the transmitted energy increases by 120.9 % and 130.2 %. Under confining pressure, the incident energy increases by 142.1 % and 109.5 %, while the transmitted energy increases by 154.9 % and 132.0 %. Under true triaxial conditions, the rocks exhibited shear failure as their failure mechanism. The argillaceous siltstone displayed crack propagation in a “V”-shaped pattern on the intermediate principal stress plane, while quartzite exhibited double-crack shear failure on the intermediate principal stress plane.