Abstract: Mechanical characteristics of saturated argillaceous dolomite under freezing–thawing cycles were tested by low temperature numerical control incubator BCD-218 C and computer-controlled electronic versatile testing machine WDW3100. In uniaxial compressive state, characteristics of stress–strain curves and law of peak stress, peak strain, elastic modulus and Poisson's ratio varying with freezing-thawing cycles were analyzed. Base on existing theory of damage mechanics, damage constitutive model of taking freeze-thaw cycle times and strain as control variables were established by introducing slope increase trend coefficient (correction coefficient). The results show that peak stress, peak strain and elastic modulus decrease exponentially; while Poisson's ratio increases linearly with increase of freezing-thawing cycles. For the effects of freezing and thawing cycles, the short line shape gentle stage appears after the first stage (compaction stage) in complete stress-strain curves, during this period, the rock shows partial slippage phenomenon. In addition, failure mode of the rock transforms from brittleness to ductility, which has pre-peak plastic hardening and post peak strain softening behavior. Theoretical constitutive model coincides with experimental results.

Key words: argillaceous dolomite, freezing-thawing cycles, mechanical characteristics, slope increase trend coefficient, damage constitutive model