The growth and evolvement features of crack are of great significance to study the failure mechanism of rock mass and valuate the stability of the cavity. In this study, in order to obtain the mechanics parameters and external macroscopic crack propagation characteristics of red sandstone, triaxial compression tests were carried out. Based on the experimental results, a numerical model was established through the reasonable parameter calibration by the PFC^3D software. The internal and external crack propagation processes of red sandstone under triaxial compression were simulated. Moreover, to verify the simulation results, the CT scanning and three-dimensional reconstruction technologies were used to observe the internal crack state of the specimens. The results showed that the internal crack failures occurred first at the end of the rock specimen. Then, the microcracks continued to accumulate and expand under the combined action of axial stress and confining pressure. The accumulated microcracks finally converged to form a macroscopic oblique shear failure. Based on the homogenizing treatment and reasonable parameter calibration, the internal and external crack expansion and evolution processes of the rock were simulated by the PFC^3D model and the simulation results are consistent with the results obtained from the triaxial compression test and the CT scanning. The macro- and microfailure mode of crack propagation of the specimen deepens the understanding of rock failure mechanism. The PFC^3D homogenization simulation method provides a new feasible method to study the macro- and microfailure mode of internal and external crack propagation of rock under compression.

中文翻译：

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不同围压下红砂岩宏微裂纹扩展机理的3D数值模拟与CT验证研究

裂缝的扩展演化特征对于研究岩体破坏机理和评价空腔稳定性具有重要意义。本研究为获得红砂岩力学参数和外部宏观裂纹扩展特性，进行了三轴压缩试验。根据实验结果，通过PFC ^3D合理的参数标定建立了数值模型。软件。模拟了三轴压缩下红砂岩的内外裂纹扩展过程。此外，为了验证模拟结果，采用CT扫描和三维重建技术观察试件内部裂纹状态。结果表明，内部裂纹破坏首先发生在岩石试样的末端。然后，微裂纹在轴向应力和围压的共同作用下不断积累和扩展。累积的微裂纹最终会聚，形成宏观的斜切破坏。在均质化处理和合理参数标定的基础上，利用PFC ^3D模拟了岩石的内外裂纹扩展演化过程。模型和仿真结果与三轴压缩试验和CT扫描得到的结果一致。试件裂纹扩展的宏观和微观破坏模式加深了对岩石破坏机制的理解。PFC ^3D均质化模拟方法为研究受压岩石内外裂纹扩展的宏观和微观破坏模式提供了一种新的可行方法。