基于Mohr-Coulomb准则的岩石损伤统计本构模型

STATISTICAL CONSTITUTIVE MODEL FOR ROCK DAMAGE BASED ON MOHR-COULOMB CRITERION

廖华林 李根生

Liao Hualin Li Gensheng

中国石油大学石油工程学院, 山东东营 257061 中国石油大学石油天然气工程学院, 北京 102249

通过损伤变量来建立合适的岩石本构模型可以更真实地反映岩石的破坏过程。基于岩石微元强度概率分布理论,以Mohr-Coulomb破坏准则作为分布参量,从理论上建立了岩石损伤变量演化方程和三轴条件下损伤统计本构模型,可采用曲线拟合法与极值法求解所建立模型的参数。用试验结果对所建模型进行了验证,较好的吻合性说明所建模型是合理的。研究表明,用Mohr-Coulomb准则作为统计分布变量建立的损伤模型能够较好地反映岩石内部缺陷分布和变形特征,真实反映岩石强度受应力状态影响的现象,在岩石破碎和井壁稳定等方面具有一定的应用价值。

The process of rock failure can be much reflected by an appropriate constitutive model with damage variables.Based on rock micro-unit strength,the theoretical equations of damage variables evolution and statistical constitutive model for rock damage are established with Mohr-Coulomb damage criterion as distribution variable.Meanwhile,tri-axis constructive model is established,and parameters in the model can be calculated with arbitrary Tri-axis experimental data by using curve fitting and extreme value methods.So it is easy for engineering applications.The model is verified by experiments and agrees well with each other.The investigation shows rock strain characteristics under loads and the constructive relation between strain and stress of rock materials can be well reflected by the constructive model with damage variable based on Mohr-Coulomb damage principle as distribution variable.The model would be easily applied in practices.

10.3969/j.issn.1000-7393.2005.06.025