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Abstract Frost heaving pressure in rock mass undergoes a process of initiation，development and dissipation under the freezing-thawing condition，which results in the fatigue degradation of the physical and mechanical properties of rock. The freezing-thawing damage model and the damage evaluation method are the key problems for the rock mass in cold regions. There are many evaluation indexes of freezing-thawing damage including the porosity，the longitudinal wave velocity and the elastic modulus. The frost heaving pressure was considered to be equivalent to the triaxial tensile stress for frozen rock mass. A freezing-thawing fatigue damage model was established based on the equivalent triaxial tensile stress. The equation describing the freezing-thawing damage variation has the same expression but the different physical meaning with that obtained under repeated uniaxial tensile stress. A new unified damage variable depending on the p-wave velocity and the porosity was deduced based on the definition of the dynamic modulus of elasticity. The damage variable includes the effect of dual physical parameters，and is a better prediction index for the uniaxial compressive strength under different freeze-thaw cycles. The loss of 40% of dynamic elastic modulus was defined as the damage threshold. With the damage threshold，the maximum failure freeze-thaw cycle was determined. The freezing-thawing damage model was solved in combination with the unified damage variable. Finally，the validity and applicability of the freezing-thawing fatigue damage model were illustrated through two examples.
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2015, Vol. 34 
