Guo Xiaoxiao, Tang Yang, Liu Jianfeng, Chen Cancan, Zhang Hailong, Zhang Fan, Okubo Seisuke
School of Civil Engineering, Chongqing University of Arts and Sciences, Chongqing, 402160, China.
College of Water Resource and Hydropower, Sichuan University, Chengdu, 610065, China.
Sci Rep. 2024 Aug 19;14(1):19211. doi: 10.1038/s41598-024-70252-6.
Understanding the mechanical characteristics of rocks when subjected to direct tension is crucial for assessing the stability of rock formations. Within the scope of this research, a series of tests was conducted using Tage tuff to assess the deformation behavior and crack extension of rock under direct tension. The axial, lateral, and shear strain fields as well as crack propagation, localized deformation behavior, and failure mode of the rocks were analyzed using three-dimensional digital image correlation method. The results showed that the axial strain fields on the specimen surface were heterogeneous, with different locations and localization occurring in the pre-peak stage, which was similar to the evolution of shear strain, whereas the lateral strain only showed slight changes. The crack extension direction was inferred, indicating that both tensile and shear stress occurred in the tests. Furthermore, different stress-strain responses were observed for the inside and outside of the localized bands. Then, the surface patterns of specimen failure were scanned and analyzed to assess the failure mode and residual strength of the specimen under direct tensile stress. Finally, the results of direct tension, uniaxial compression, and Brazilian split tests for Tage tuff were compared, and the complete stress-strain curve of uniaxial tension (UT) was simulated using a nonlinear-variable-compliance constitutive equation. This study provides a deeper understanding into the damage behavior of rocks under direct tension.
了解岩石在直接拉伸作用下的力学特性对于评估岩层稳定性至关重要。在本研究范围内，使用 Tage 凝灰岩进行了一系列试验，以评估岩石在直接拉伸下的变形行为和裂纹扩展情况。采用三维数字图像相关方法分析了岩石的轴向、横向和剪切应变场以及裂纹扩展、局部变形行为和破坏模式。结果表明，试样表面的轴向应变场不均匀，在峰值前阶段不同位置出现了应变局部化，这与剪切应变的演化相似，而横向应变仅显示出轻微变化。推断了裂纹扩展方向，表明试验中同时存在拉伸应力和剪切应力。此外，在局部化带的内部和外部观察到了不同的应力 - 应变响应。然后，扫描并分析了试样破坏的表面图案，以评估试样在直接拉伸应力下的破坏模式和残余强度。最后，比较了 Tage 凝灰岩的直接拉伸、单轴压缩和巴西劈裂试验结果，并使用非线性变柔度本构方程模拟了单轴拉伸（UT）的完整应力 - 应变曲线。本研究为深入了解岩石在直接拉伸下的损伤行为提供了依据。
