Advances in dynamic test of deep rocks considering in-situ mechanical and hydraulic conditions

Determining the dynamic behaviors of deep rocks is important but challenging for deep underground rock engineering. Recently, great advances have been made by researchers in dynamic tests of deep rocks considering in-situ mechanical and hydraulic conditions. It is thus imperative to systematically review the progress in this field. This paper focuses on the dynamic experiments of deep rocks using the modified split Hopkinson pressure bar (SHPB), including new advances in experimental apparatuses, methodologies, and results. A comprehensive introduction to the principles of the triaxial confinement SHPB, the true triaxial SHPB, and SHPB with a coupled hydraulic-mechanical device is provided. The development of these systems for conducting dynamic tests of deep rocks is briefly presented. Moreover, the experimental methods and results for quantifying dynamic compressive, tensile, flexure, and shear strengths and mode I/II fracture toughness of rocks under axial preload, hydrostatic pressure, triaxial stress state, and coupled hydraulic-mechanical condition are systematically discussed, and the rate-dependent characteristics and mechanisms of deep rocks under various geological occurrence conditions are also summarized.