Study on physical and mechanical properties and freezethaw damage models of granite under freeze-thaw cycles

Song Xue¹YongQiong Hu²Chaojun Jia^2*Liang Wang²

• ¹Hunan Baige Water Conservancy Construction Co., Ltd, Changsha, China
• ²School of Civil Engineering, Central South University, Changsha, China

To describe the evolution of freeze-thaw damage in rocks and quantitatively analyze the degree of damage, a freezethaw damage model based on continuum damage mechanics and thermodynamics is proposed. Taking granite as the research object, its physical and mechanical properties, acoustic emission characteristics, and failure modes were studied through freeze-thaw cycling, uniaxial compression, acoustic emission detection, and CT scanning experiments, and the validity of the model was verified. The results show that with the increase in the number of freeze-thaw cycles, the porosity of the specimens significantly increases, while the uniaxial compressive strength, elastic modulus, and wave velocity of granite decrease exponentially. During uniaxial compression, the cumulative acoustic emission ring counts and energy increase in a stepwise manner. In the early stage of loading, the signals are few, but as the stress increases and the cracks propagate, the signals significantly increase and reach a maximum at the stress peak. An increase in the number of freeze-thaw cycles leads to a decrease in the rate of increase of ring counts and energy in the early stage of loading and a reduction in their cumulative values. The failure mode changes from "X"-shaped shear failure to conical shear failure, with the shear triangle gradually increasing and shifting upward, and the number of main cracks decreasing. The experimental results are consistent with the theoretical model, indicating that the model can accurately describe the mechanical behavior and damage evolution of rocks under freeze-thaw cycling.