Han Weige, Zhu Zhengguo, Zhou Hao, Che Longzhou, Peng Haorui
Key Laboratory of Roads and Railway Engineering Safety Control (Shijiazhuang Tiedao University), Ministry of Education, Shijiazhuang, 050043, China.
State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang, 050043, China.
Sci Rep. 2025 Jul 10;15(1):24816. doi: 10.1038/s41598-025-09376-2.
Accuracy of tensile strength is crucial for guiding the stable construction of rock engineering. In this study, a spherical specimen was used for testing tensile strength, and its results were compared with Brazilian split method. A numerical analysis of tensile strength was performed for two kinds of specimens using cohesive zone model. The fracture process and acoustic emission (AE) distribution characteristics of spherical and Brazilian disc specimens were analysed to determine similarities and differences between them. During the axial compression, the stress distribution in Brazilian disc specimen was relatively concentrated, which indirectly limited the range of potential fracture surface. The tensile AE events were concentrated in the middle of the specimen. Therefore, the obtained tensile strength tends to be the strength parameter of a certain section. However, the stress concentration zone in a spherical specimen was more widely distributed, showing three-dimensional characteristics, which did not pre-define the potential fracture surface and increased the randomness of rock rupture. Low energy AE events were distributed discretely in three-dimensional space, and high energy AE events constituted a significant fracture surface, which was the weakest rupture surface of the spherical specimen. The results of the spherical specimen had a smaller standard deviation and larger tensile-shear ratio, and the tensile strength obtained is lower than that of the Brazilian disc specimen. Therefore, the tensile strength obtained by a spherical specimen can better reflect the tensile fracture characteristics under three-dimensional state. The result of this study provides a new idea for the tensile strength testing method.
抗拉强度的准确性对于指导岩石工程的稳定施工至关重要。在本研究中，采用球形试样测试抗拉强度，并将其结果与巴西劈裂法进行比较。使用粘结区模型对两种试样进行了抗拉强度的数值分析。分析了球形和巴西圆盘试样的断裂过程和声发射（AE）分布特征，以确定它们之间的异同。在轴向压缩过程中，巴西圆盘试样中的应力分布相对集中，这间接限制了潜在断裂面的范围。拉伸AE事件集中在试样中部。因此，所获得的抗拉强度往往是某一截面的强度参数。然而，球形试样中的应力集中区分布更广泛，呈现三维特征，没有预先确定潜在的断裂面，增加了岩石破裂的随机性。低能量AE事件在三维空间中离散分布，高能量AE事件构成一个显著的断裂面，这是球形试样最薄弱的破裂面。球形试样的结果具有较小的标准差和较大的拉剪比，且所获得的抗拉强度低于巴西圆盘试样。因此，球形试样所获得的抗拉强度能更好地反映三维状态下的拉伸断裂特性。本研究结果为抗拉强度测试方法提供了新思路。
