Experimental study of shear behavior of rock–shotcrete interface under dynamic shearing: insights from interface roughness and strain rate

Abstract

Rock–shotcrete structures are often suffered from dynamic shearing. However, the understanding of the dynamic shear response of rock–shotcrete structures is still at its infancy. To investigate the effects of strain rate and interface roughness on the dynamic shear response of rock–shotcrete structure, laboratory tests were carried out on the modified double notched sandstone–concrete specimen. Testing results show that the dynamic shear strength and dynamic peak strain of sandstone–concrete specimens are both far less than those of sandstone and concrete specimens. With increasing strain rate, the dynamic shear strength of sandstone–concrete specimen increases and the failure mode changes from interfacial shear failure to the mixed failure, i.e., the interfacial, concrete and sandstone shear failure. With the increase in interface roughness, the failure mode changes from sliding fracture to shear-off fracture, leading to an increase in dynamic shear strength and shear peak strain of sandstone–concrete specimens. In addition, it is the smallest sawtooth angle at the sandstone–concrete interface that dominates the dynamic shear strength of sandstone–concrete specimens. The findings in the present study could facilitate understanding the shear behavior and failure mechanism of the rock–shotcrete structure subjected to dynamic loading and be helpful in the efficient design, reinforcement and stability of rock–shotcrete engineering.