中文摘要：

在冻融条件下岩石微裂隙中的水发生相变,体积膨胀,对微裂隙产生很大的冻胀力,当冻胀力超过岩石的抗拉强度时,微裂隙扩展。温度升高时,水又进入新的微裂隙,如此反复循环造成了岩石的损伤。据此,将岩石中的微裂隙等效为扁平状椭圆裂隙,基于断裂力学建立了单条微裂隙下裂隙扩展长度与冻胀力的关系,考虑岩石中微裂隙的分布,将岩石冻融条件下的应变分解为初始损伤应变、附加损伤应变和塑性应变,建立了弹塑性冻融损伤本构模型。最后,通过岩石冻融试验对该模型的合理性进行了验证,结果表明,该模型能够较好地模拟岩石在不同冻融次数下的应力-应变关系曲线。

英文摘要：

A brittle material such as rock deteriorates when subjected to freezing and thawing, it is generally observed that water phase transition due to temperature changing is the main reason of rock deterioration. Hydraulic pressure is generated by 9% volume increase of freezing water in closed crack. The pressure makes the crack expand and when the temperature rises, water moves to new cracks. The repeated cycles create new damage of rock. The freezing and thawing process of rock is also affected by a number of factors such as length of cracks, permeability, and heaving stress. The relationship between frost heave stress and crack extension length of a single fracture is established based on elastoplastic mechanics and fracture mechanics. Combined the equation of relationship between ice pressure and microcrack propagation length, the initial damage compliance tensor of the rock under the different freezing-thawing cycles can be calculated. According to the distribution of microcracks, the strain of rock induced by freezing-thawing can be decomposed into the initial damage strain, additional damage strain and plastic damage strain; and an elastoplastic damage model for rock under different number of freezing-thawing cycles is developed based on frictional sliding of pre-existing microcracks in this work. In the damage model, the plastic yield criterion of Drucker–Prager yield criterion is used simultaneously with the micromechanics damage model to simulate the inelastic deformation of rocks and Voyiadjis＇ strain hardening function under compression; and it is used to define plastic behaviors of such materials. The calculated results show, the crack propagation length increases nonlinearly with increasing the crack and the compressive strength under different cycles of freezing and thawing. Finally, the applicability of the model is validated by freezing-thawing experiment, it is shown that the developed model can simulate the stress-strain curves under different of freeze-thaw cycles better.