Abstract: Based on non-associative flow theory and elasto-plastic coupling theory, the instability of engineering rock-like materials was investigated. Due to the stiffness deterioration properties of engineering rock-like materials, material instabilities may occur in softening plastic, perfectly plastic and low hardening plastic phases. For the elasto-plastic coupling theory, positive definiteness of the elasto-plastic coupling constitutive matrix was discussed, and the condition of material instability was obtained. For the plastic potential theory, symmetric part of the constitutive matrix was used for material stability analysis and same results could be obtained.

Key words: engineering rock-like materials, stiff testing machine, material stability, material instability, stiffness deterioration, elasto-plastic coupling theory, plastic potential theory, Drucker-Prager criterion

摘要： 基于非关联流动理论和弹塑性耦合理论, 研究工程岩石类材料的不稳定性。由于工程岩石类材料具有刚度劣化特性, 岩石类材料在软化塑性、理想塑性和低强化塑性情况下均可能呈现不稳定。对于弹塑性耦合理论, 可通过本构矩阵正定性的讨论, 得到工程岩石类材料的不稳定条件; 对于塑性势理论, 可通过本构矩阵对称部分的正定性来研究材料的稳定性, 能够得到相同的结果。

关键词: 工程岩石类材料, 刚性试验机, 材料稳定性, 材料不稳定性, 刚度劣化, 弹塑性耦合理论, 塑性势理论, Drucker-Prager准则