Mechanical Response and Damage Evolution of Marble Under Triaxial Constraint and Cyclic Loading–Unloading
摘要
To address the challenges of surrounding rock damage at different construction stages, triaxial cyclic loading and unloading tests with a constant lower stress limit were conducted on marble under different confining pressures (σ3). The mechanical behavior, failure modes, and energy evolution were comprehensively analyzed. Cyclic damage was quantified using multiple methods incorporating initial damage D0 derived from equivalent strain. An exponential damage evolution model was subsequently established to account for the influence of σ3 and the three-stage damage characteristics. The results show that the stress–strain curves exhibit a distinct stress memory effect, with the peak strength increasing by approximately 32% as σ3 rises from 10 to 25 MPa. With cycling, the elastic modulus first increases and then decreases, while Poisson’s ratio follows an inverse S-shaped trend. Axial and lateral plastic strains exhibit a three-stage evolution with a spoon-shaped (concave-upward) trend, in which lateral deformation dominates the overall deformation process. Increasing σ3 delays the onset of volumetric dilation from the 11th to the 17th cycle and increases the energy storage limit by a factor of 1.4. Shear failure prevails as the dominant failure mode, with the fracture angle decreasing from 72° to 49° as σ3 increases. Both total and dissipated energy increase nonlinearly with the cycle number, while elastic energy first rises and then declines before failure. Damage characterized by the maximum strain, cumulative dissipated energy, and cumulative plastic axial strain methods effectively captures the progression from D0 to failure. The established exponential model provides a predictive framework for stability evaluation of deep rock masses.