Research on damage characteristics and constitutive model of rock mass under true triaxial cyclic loading based on acoustic emission

• True triaxial cyclic loading simulates mining stress, revealing distinct damage evolution in sandstone with σ1 cycling primarily affecting axial strain and σ2 cycling governing intermediate principal strain. • Elastic modulus of sandstone decreases exponentially and Poisson's ratio increases linearly with increasing cyclic load amplitude, indicating progressive stiffness degradation. • Acoustic emission b-value trends and rise angle-average frequency analysis effectively identify failure mode transitions from tensile to shear with increased intermediate principal stress. • The constitutive model based on AE cumulative ringing count accurately predicts sandstone damage behavior, with damage variable decreasing with σ2 during σ1 cycling but first decreasing then increasing with σ3 during σ2 cycling.