The influence of interface morphology on the tensile properties and interface stress of rock-shotcrete Brazilian discs

In tunnelling and mining applications, the rock-shotcrete interface is crucial for structural stability at the initial support stage, but its complex stress distribution remains poorly understood due to the rock surface depressions. This study employs a series of simulations and model tests to investigate the influence of depression shape and depth on the interface. The results indicate that increased depression depth negatively impacts nominal tensile strength (NTS) and crack initiation energy, although these effects are lessened with rectangular-toothed depressions. The tensile stress on non-depressed surfaces is unaffected by depression depth but is influenced by its shape. Due to the concentration of tensile stress, non-concave interfaces are most prone to failure. In underground rock early support, the construction method of rectangular depression chiselling is more conducive to improving the strength of the shotcrete-rock interface.