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目前岩石动态损伤本构模型未能很好地同时考虑临界应变及已有损伤对被激活微裂纹数目的影响,为此,基于微裂纹在单轴压缩荷载下的扩展机理,提出了新的岩石单轴压缩动态损伤本构模型。在假定岩石中被激活的微裂纹数服从Weibull分布的基础上,首先,通过临界应变对被激活微裂纹数目的影响,建立了考虑临界应变及微裂纹扩展长度的单轴压缩损伤本构关系;其次,根据微裂纹在单轴压缩下的翼裂纹扩展方程,考虑翼裂纹扩展过程中的惯性效应及翼裂纹扩展速度与应变率之间的关系,建立了单轴压缩下岩石动态细观损伤本构模型。最后采用数值算例对模型的合理性进行了验证。结果表明:随着Weibull分布参数k和m的增加,岩石动态抗压峰值强度分布减小和增加,且m的影响更为显著。随着微裂纹摩擦系数、岩石断裂韧性和应变率的增加,岩石动态抗压峰值强度增加;而随着微裂纹长度的增加,岩石动态峰值强度则降低。该结论与目前的研究成果较为一致,说明了该模型的合理性。
At present, the dynamic damage constitutive model of rock failed to consider well both the critical strain and the existing damage on the number of activated microcracks. Therefore, based on the expansion mechanism of microcracks under uniaxial compressive load, a new rock Uniaxial compression dynamic damage constitutive model. Based on the assumption that the number of microcracks activated in rock obeys the Weibull distribution, firstly, the uniaxial compression damage constitutive relation considering critical strain and microcrack propagation length is established by the influence of critical strain on the number of activated microcracks. Secondly, according to the crack growth equation of microcracks under uniaxial compression, considering the relationship between the inertial effect and the rate of wing crack growth and the strain rate in the process of wing crack growth, the dynamic meso-damage Model. Finally, numerical examples are used to verify the rationality of the model. The results show that with the increase of Weibull distribution parameters k and m, the peak compressive strength distribution of rock decreases and increases, and the influence of m is more significant. With the increase of microcrack friction coefficient, rock fracture toughness and strain rate, the peak dynamic compressive strength of rock increased, while the dynamic peak strength decreased with the increase of microcrack length. This conclusion is more consistent with the current research results, indicating the rationality of the model.