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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。
Under freezing and thawing conditions, the water in the micro-cracks in the rock undergoes phase transformation and expands in volume, resulting in a large frost heaving force on the micro-cracks. When the frost heaving force exceeds the tensile strength of the rock, the micro-cracks expand. As the temperature rises, the water enters new micro-cracks, causing repeated damage to the rock. Based on the above results, the microcracks in the rock are equivalent to flat oval cracks. Based on the fracture mechanics, the relationship between the crack propagation length and the frost heave force under a single micro-crack is established. Considering the distribution of micro-fractures in the rock, The strain is decomposed into the initial damage strain, the additional damage strain and the plastic strain, and the elastic-plastic freeze-thaw damage constitutive model is established. Finally, the rationality of this model is verified by rock freeze-thaw test. The results show that this model can simulate the stress-strain curve of rock under different freezing-thawing times.