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Abstract For freeze-thaw and loaded rock in engineering structures in cold regions，a damage variable is proposed with a new meaning，and three new conceptions are put forward，which are freeze-thaw damage，loaded damage and total damage. Defining the initial damage state as basic state，the damage model of freeze-thaw and loaded rock is established considering the heterogeneity of rock at mesoscopic level using damage mechanical theory and generalized principle of strain equality. The damage evolutions of meso-structure and macro-damage behaviors of rocks are described by damage variable and constitutive equation，which are in good agreement with the actual freeze-thaw breakage. It is shown that the mechanical properties of freeze-thaw and loaded rocks in engineering structures are determined by freeze-thaw，load and the coupling effects. The combined effect of freeze-thaw and load in the total damage of rock has obvious nonlinear properties，but the coupling effect will weaken the total damage. The weights of influence factors are determined by the lithology and initial damage states of the rocks，so the rock has different damage propagation characteristics. In comparison，sandstone is more sensitive to the freeze- thaw cycles，and load damage will lead to the destruction of shale eventually.
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Received: 21 July 2009
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