Study on the mechanical response and failure behavior of the rock-like material with hole-bolt composite structure

To investigate the influence of bolt pre-tightening force and hole-bolt spacing on the mechanical responses and failure characteristics of rock-like materials with hole-bolt composite structures, a comprehensive set of physical tests was carried out. The findings suggest that enhancing the pre-tightening force improves the peak stress and elastic modulus of the material. However, these properties initially increase and then diminish with widening hole-bolt spacing. An increase in pre-tightening force results in more fractures around the hole, altering the material's failure mode from tensile-shear to purely tensile. Additionally, as the hole-bolt spacing expands, the tensile crack positioned above the hole progressively shifts away from the bolt, leading to a transition in failure mode from tensile to tensile-shear. Field tests confirm that the bolt force proximate to the pressure relief hole remains significantly greater than that at a distance, establishing hole-bolt spacing as a critical factor in anchorage stability. •The mechanical response and failure behavior of hole-anchor composite rock-like materials was investigated.•The physical test considers the pre-tightening force and hole-bolt spacing on the influence of the rock-like material.•The failure process of the rock-like material are successfully captured by the Digital Speckle Correlation Method (DSCM).•The bolt force is influenced by the distance from the pressure relief in the physical test and verified through the field test.