锦屏大理岩蠕变损伤演化细观力学特征的数值模拟研究

岩石的蠕变损伤和断裂是岩石流变效应的重要表现形式，但其损伤演化过程往往难以直观观测，为此，采用二维颗粒流数值模拟方法(PFC2D)对岩石的蠕变损伤和断裂的细观力学机制进行了分析。在锦屏大理岩室内试验基础上，利用颗粒流应力腐蚀模型(PSC)，建立了能反映其短期和长期强度特征的柱状岩样数值模型，并开展了大量数值试验。结果表明，蠕变损伤的演化过程与暂态的损伤演化过程具有明显的差异。在岩样蠕变损伤过程中，其内部微裂纹多沿加载方向开裂且分布均匀，先快速增加再稳定扩展，最后则发生快速断裂。当荷载较小时，岩样宏观上呈现劈裂破坏特征，当荷载较大时，岩样呈现剪切破坏特征。在岩样蠕变损伤初始和稳定演化阶段的前期，荷载大小对岩样的损伤演化过程影响不大；在稳定演化阶段的后期至断裂过程中，低荷载下岩样的损伤增速比高荷载下快。

Numerical simulation of mesomechanical characteristics of creep demage evolution for Jingping marble

Creep damage and fracture of rock are the main forms of rock creep effect. But the internal damage evolution process of rock is difficult to be observed directly. So, the particle flow code (PFC2D) is used to analyze the mesomechanism of creep damage and fracture for Jingping marble. Based on the laboratory test data, the particle flow stress corrosion model (PSC) is used to establish the numerical model of Jinping marble. The model can simulate the short-term and long-term strength characteristics of Jinping marble. The numerical simulation result shows that the creep damage evolution process is significant different from the process in transient state. In the creep damage evolution process, the microcracks almost dehisce along the load direction; and the distribution of them is even. The number of microcracks in rock specimen increases rapidly firstly, and then increases stably. Finally, the microcracks evolution unstably till the rock sample fracture. When the load is lower, the rock specimens present the splitting failure state. However, when the load is higher, the rock specimens present the shear failure state. In the initial damage stage and prophase of stable evolution stage, the load magnitude has a little effect on the creep damage process of rock specimens. In the later stage of stable evolution stage and the failure stage, the damage of rock specimens under lower load increases faster than the specimens under higher load.