AE responses, energy evolution, and damage constitutive model of jointed rock-like material subjected to unilaterally...

Faults, joints, and other weak structural surfaces are commonly present in the surrounding rocks of tunnels and goafs. To investigate the effect of different joint angles on the instability and failure of surrounding rock, joints of varying angles are fabricated using 3D printing technology. Unilateral confined compression tests are conducted using a custom L-shaped mold to systematically examine the mechanical response, acoustic emission (AE) characteristics, macroscopic failure modes, energy evolution, and damage constitutive behavior of the jointed specimens. The results show that the joint angle significantly influences the mechanical properties and macroscopic failure characteristics of the specimens. Compressive strength reaches its maximum at a joint angle of 90°, whereas the highest degree of specimen failure occurs at a joint angle of 30°. Stress reduction is accompanied by increased AE activity and a decline in dynamic b-values. Additionally, the elastic energy of the jointed specimen rises with increasing joint angle, resulting in a higher energy storage capacity. The compaction coefficient K is incorporated to develop a damage constitutive model for jointed rock masses under unilateral confined compression, and the theoretical predictions closely match the experimental results.