Energy characteristics and damage constitutive model of pre-cracked granite with or without filling materials

In order to study the effects of pre-crack inclination angle and filling material on granite, uniaxial compression tests were performed on pre-cracked granite specimens without filling material and specimens filled with epoxy resin, gypsum, and organosilicon. Results indicate that the peak strength and apparent stiffness of pre-cracked granite without filling materials increase with increasing pre-crack inclination angle. The strain energy absorbed by the filling material improves the energy storage limit, inhibits the energy release effect when microcracks are connected to each other, and ultimately improves the compressive resistance and energy storage capacity. The strengthening effect of gypsum and epoxy resin is relatively better, which is more significant when the pre-crack inclination angle equals 0°–60°. Finally, a damage constitutive model is established, which is in good agreement with the test and numerical simulation data. The results can provide reference for the research of grouting reinforcement of rock masses.