Dynamic Responses and Failure Behaviors of Saturated Rocks Subjected to Repetitive Compression–Shear Impacting

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.