Effect of fissure angle on energy evolution and failure characteristics of fractured rock under uniaxial cyclic loading.

To study the influence of fissure angle on the rock damage process and energy evolution characteristics, uniaxial cyclic loading and unloading tests were conducted on fractured rock specimens with different prefabricated fissure angles. The stress-strain curves, mechanical properties, and failure characteristics were analyzed. Subsequently, the energy evolution characteristics and failure mechanisms were investigated. The results showed that the stress-strain curves of fractured specimens fluctuated in the pre-peak phase and rapidly declined in post-peak phase. The peak stresses and strains of fractured specimens initially decreased and then increased with an increase in the fissure angle, whereas the elastic modulus first increased and then decreased. With an increase in the fissure angle, specimen failure changed from shear damage to tensile damage. The input, elastic, and dissipation energies of fractured specimens non-linearly increased with an increase in cyclic loading and unloading. As the number of cycles increased, the energy density decreased in segments with an increase in the fissure angle, and there was a rapid increase in the dissipation energy density before failure occurred. The results can provide a reference for the study of fractured rock failures and their prevention and control design in the field.