Experimental Study on Creep Characteristics and Damage Model of Carbonaceous Slate After Freeze-Thaw

Taking the carbonaceous slate of Zhuokeji tunnel on the Wenchuan-Ma, erkang expressway as the research subject, triaxial compression creep tests were conducted under various freeze-thaw cycles to analyze the creep strain characteristics and long-term strength of the carbonaceous slate. Assuming that the aging damage of rock under load follows the Weibull probability density distribution, the loaded damage variable is defined. The freeze-thaw damage variable is defined according to the phenomenological theory of damage mechanics. Considering the coupling effect of freeze-thaw and stress, a total damage variable for freeze-thaw and load is constructed. Based on the creep behavior of carbonaceous slate, the structure of the H-H|N-N|S creep model is determined. Based on this, the damage evolution is carried out, and a new creep damage model that can reflect the coupling of freeze-thaw and stress is obtained, which is extended to a three-dimensional stress state. The solution method for model parameters is provided, and the damage evolution law is analyzed. The creep characteristics of carbonaceous slate are identified using the established model. A traditional model is introduced for comparison, and the simulation comparison curve is analyzed to verify the feasibility and rationality of the new model.