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Investigation of microcracking behaviors in brittle rock using polygonal grain-based distinct method
International Journal for Numerical and Analytical Methods in Geomechanics ( IF 4 ) Pub Date : 2021-06-17 , DOI: 10.1002/nag.3246 Zhao Wang 1, 2 , Tiehang Wang 1 , Saisai Wu 2 , Yanzhou Hao 3
International Journal for Numerical and Analytical Methods in Geomechanics ( IF 4 ) Pub Date : 2021-06-17 , DOI: 10.1002/nag.3246 Zhao Wang 1, 2 , Tiehang Wang 1 , Saisai Wu 2 , Yanzhou Hao 3
Affiliation
The failure process in brittle rocks is an important topic in rock mechanics, whose good understanding assists in predicting the strength and deformation characteristics of rocks. Because it is difficult to directly observe microcracks in laboratory tests, a numerical model is a useful tool for investigating microcracking behaviors. However, the mechanism of microcrack evolution is still unclear at the grain scale considering the microscopic heterogeneities. This paper proposes a polygonal universal distinct element code grain-based model to solve this problem. Compared with other grain-based models, this model is different in that mineral grains are subdivided into polygon blocks. The grain size, composition, and bond types of the contacts are incorporated, and both inter- and intra-grain cracks are mimicked. Subsequently, micro-parameters of the blocks and contacts are carefully calibrated according to the laboratory results. Following this, the calibrated model is employed to study the microcracking behaviors of granite in unconfined compression, confined compression, and Brazilian splitting tests. Both the cumulative numbers and locations of microcracks in different grains are recorded, and the types of macroscopic fractures are identified. The modeling results show that tensile cracks dominate the generated microcracks in the low confined compression tests, and the macroscopic fracture pattern is axial splitting. Shear cracks are dominant in the high confined compression tests, and the macroscopic failure pattern is X-type shear failure. The simulated results are consistent with those observed in the laboratory tests, and thus, may assist in improving rock acoustic emission monitoring and understanding the damage process of rock.
中文翻译:
使用基于多边形颗粒的区分方法研究脆性岩石中的微裂纹行为
脆性岩石的破坏过程是岩石力学的一个重要课题,对脆性岩石的理解有助于预测岩石的强度和变形特性。由于在实验室测试中很难直接观察到微裂纹,因此数值模型是研究微裂纹行为的有用工具。然而,考虑到微观非均质性,在晶粒尺度上微裂纹演化的机制仍不清楚。本文提出了一种基于多边形通用不同元素代码粒度的模型来解决这个问题。与其他基于颗粒的模型相比,该模型的不同之处在于将矿物颗粒细分为多边形块。结合了触点的晶粒尺寸、成分和键类型,并模拟了晶粒间和晶粒内裂纹。随后,根据实验室结果仔细校准块和触点的微观参数。在此之后,校准模型用于研究花岗岩在无侧限压缩、有限压缩和巴西劈裂试验中的微裂纹行为。记录了不同晶粒中微裂纹的累积数量和位置,并识别了宏观裂纹的类型。建模结果表明,在低限压试验中,产生的微裂纹以拉伸裂纹为主,宏观断裂模式为轴向劈裂。剪切裂纹在高约束压缩试验中占主导地位,宏观破坏模式为X型剪切破坏。模拟结果与实验室测试中观察到的结果一致,因此,
更新日期:2021-08-13
中文翻译:
使用基于多边形颗粒的区分方法研究脆性岩石中的微裂纹行为
脆性岩石的破坏过程是岩石力学的一个重要课题,对脆性岩石的理解有助于预测岩石的强度和变形特性。由于在实验室测试中很难直接观察到微裂纹,因此数值模型是研究微裂纹行为的有用工具。然而,考虑到微观非均质性,在晶粒尺度上微裂纹演化的机制仍不清楚。本文提出了一种基于多边形通用不同元素代码粒度的模型来解决这个问题。与其他基于颗粒的模型相比,该模型的不同之处在于将矿物颗粒细分为多边形块。结合了触点的晶粒尺寸、成分和键类型,并模拟了晶粒间和晶粒内裂纹。随后,根据实验室结果仔细校准块和触点的微观参数。在此之后,校准模型用于研究花岗岩在无侧限压缩、有限压缩和巴西劈裂试验中的微裂纹行为。记录了不同晶粒中微裂纹的累积数量和位置,并识别了宏观裂纹的类型。建模结果表明,在低限压试验中,产生的微裂纹以拉伸裂纹为主,宏观断裂模式为轴向劈裂。剪切裂纹在高约束压缩试验中占主导地位,宏观破坏模式为X型剪切破坏。模拟结果与实验室测试中观察到的结果一致,因此,