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In waterway regulation engineering, submerged reefs are quite susceptible to the repetitive oblique strike from drop hammer and impact drilling, leading to a repetitive compression–shear impacting. Understanding the dynamic responses and failure mechanism of saturated rocks subjected to repetitive compression–shear impacting is thus of great significance for the efficient removal of submerged reefs. In this study, using the split Hopkinson pressure bar (SHPB) apparatus, the repetitive compression–shear impacting tests were conducted on the saturated and dry sandstone specimen from the harbor excavation project in Guoyuan Port (Chongqing, China). Our experimental results indicate that the increasing loading rate or shear component in the dynamic loading has a negative influence on the bearing capacity of saturated sandstone subjected to repetitive impacting. The deformability of saturated rocks increases as the impacting number or the shear component in the dynamic loading. The energy absorption ability as well as the energy utilization of the saturated rocks is highly improved by implementing repetitive compression–shear impacting, and such improvement yields an ascension limit with the increasing shear component in the dynamic loading. As the shear component introduces into the repetitive impacting loading, the failure patterns of rocks change from the relative tensile mode with a large deformation band along the loading direction to the combined compression–shear mode with two parallel large deformation bands inclined to the loading direction, the water content between the mineral grains promotes the shear failure in rock dynamic testing. These results can provide a better understanding of the dynamic responses and failure properties of saturated rocks subjected to repetitive compression–shear impacting. Highlights: Illustrated influences of repetitive compression–shear impacting on the bearing capacity and deformability of saturated and dry rocks. Investigated energy dissipation of saturated and dry rocks under repetitive combined compression–shear impacting. Revealed failure patterns of saturated and dry rocks under repetitive combined compression–shear impacting. [ABSTRACT FROM AUTHOR]

Rocks in the deep underground are likely subjected to both hydrostatic confining pressure and dynamic compression–shear load. Thus, accurately characterizing the dynamic properties and failure mechanism of hydrostatically confined rocks under combined compression–shear impacting is crucial for the stability assessment of deep underground rock structures. In this study, on the basis of an improved split Hopkinson pressure bar (SHPB) apparatus, the combined dynamic compression–shear tests are performed on inclined cylindrical sandstone specimens with hydrostatic confining pressures. During the test, the dynamic force balance of rock specimens can be well satisfied using the pulse shaping technique. Our results show that the hydrostatic confining pressure and dynamic loading rate help strengthen the load-carrying capacity of rocks. In contrast, the shear component in the dynamic load limits the dynamic peak stress of rocks. As hydrostatic confining pressure increases, the failure surface based on the Drucker–Prager criterion gradually expands outward. Under dynamic loading, the compressive deformation modulus of rocks decreases with increasing shear component in the dynamic load, contrary to its response to hydrostatic confining pressure. Fragmentation analysis indicates that the hydrostatic confining pressure and the shear component of dynamic loading restrict the fracture behavior of rocks. Besides, as the specimen inclination angle and the hydrostatic confining pressure increase, the failure pattern of rock specimens changes from the tensile-dominated failure with a truncated conical surface to the shear-dominated failure with a single shear plane along its short diagonal. [ABSTRACT FROM AUTHOR]