基于Mogi-Coulomb统计损伤本构模型及渗透性突变的研究

A Statistical Damage Constitutive Model Based on the Mogi-Coulomb and Its Application to the Study of Permeability Catastrophe

在基于Lemaitre应变等价性理论和岩石微元强度服从Weibull随机分布的基础上,引进Mogi-Coulomb准则作为岩石微元强度的表示方法;并深入研究岩石压缩破坏过程中损伤变量的变化规律。建立了统计损伤本构模型,可以较好地反映岩石在不同围压下压缩破坏对应的损伤阀值。通过岩石三轴应力-应变试验曲线对模型进行验证,并与基于Drucker-Prager和Mohr-Coulomb准则的损伤模型的模拟曲线相比较,表明基于Mogi-Coulomb准则的损伤模型能较好的模拟岩石应力应变关系;特别反映了不同应力状态对损伤阈值的影响及岩石低应力水平的线弹性特性。最后将考虑损伤阈值且基于Mogi-Coulomb准则建立的损伤统计本构模型应用于岩石渗透性突变点和对应的临界破坏强度的研究。模型的预测值与试验值较吻合,表明该模型的合理性和可行性,具有良好的应用前景。

Based on Lemaitre＇s strain equivalence and rock micro-unit strength satisfying Weibull random distribution, introducing the Mogi-Coulomb strength criterion as a computation method of rock micro-unit strength, a new statistical damage constitutive model is established after a further study of damage variable during the failure process of rock under compression, considering the damage threshold under different confining pressures. Then, the new damage constitutive model is verified according to the comparison with rock triaxial test results. The result shows that the model can better describe the stress-strain relation, specially the influence of damage threshold under different confining pressures and the linear-elastic characteristics in low stress level, compared with the Drucker- Prager and Mohr-Coulomb models. Lastly, the new model is applied to study of rock permeability catastrophe. The predictive values agree well with the experimental data. The feasibility and validity of the new model with Mogi- Coulomb criterion are verified, showing a good prospect for application.