Ge Jinjin, Jia Yongqi, Huang Wei, Yu Meilu, Ni Suqian, Xu Ying, Yu Leilei, Gu Keke
School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan, 232001, Anhui, China.
Department of Architectural Engineering, Huainan Union University, Huainan, 232001, Anhui, China.
Sci Rep. 2024 Dec 30;14(1):31840. doi: 10.1038/s41598-024-83256-z.
The mechanical behavior and fracture mechanisms of deep fractured rocks under explosive dynamic loads are critical for understanding rock instability in engineering applications such as blasting operations. This study aims to investigate how the presence of pre-existing cracks and different stress states affect the mechanical properties and fracture patterns of rock-like specimens under dynamic loading conditions. We utilized a Split Hopkinson Pressure Bar (SHPB) with an active confining pressure loading device to conduct impact compression tests on rock-like specimens containing pre-existing cracks. These tests were performed under uniaxial and triaxial stress states to simulate various in-situ stress conditions. The study revealed three key findings: (1)The dynamic compressive strength of specimens with pre-existing cracks exhibited a non-monotonic relationship with crack inclination angle under uniaxial stress, contrasting with an increasing trend under confining pressure, highlighting the significant effects of confining pressure and strain rate. (2)Confining pressure significantly altered the failure modes, with specimens failing predominantly in axial tension at 0° and 90° crack inclinations, and a mix of axial tension and shear at 30° and 60°, indicating complex failure mechanisms. (3)The pre-existing crack angle under confining pressure influenced the propagation path and fractal dimension of the specimen, with an increasing angle correlating to higher fractal dimensions and a positive impact on compression peak stress. The research provides valuable insights into the complex fracture behavior of fractured rocks under dynamic loads, which can inform the design of blasting parameters in deep engineering. It also offers critical knowledge for preventing rock instability-related disasters, thus holding significant theoretical and practical importance in the field of rock mechanics and engineering.
深部裂隙岩石在爆炸动载作用下的力学行为和断裂机制对于理解爆破作业等工程应用中的岩石失稳至关重要。本研究旨在探讨既有裂隙的存在以及不同应力状态如何影响动态加载条件下类岩石试件的力学性能和断裂模式。我们利用带有主动围压加载装置的分离式霍普金森压杆（SHPB）对含有既有裂隙的类岩石试件进行冲击压缩试验。这些试验在单轴和三轴应力状态下进行，以模拟各种现场应力条件。研究揭示了三个关键发现：（1）在单轴应力下，既有裂隙试件的动态抗压强度与裂隙倾角呈非单调关系，而在围压下呈增加趋势，突出了围压和应变率的显著影响。（2）围压显著改变了破坏模式，裂隙倾角为0°和90°时试件主要在轴向拉伸破坏，30°和60°时为轴向拉伸和剪切混合破坏，表明破坏机制复杂。（3）围压下既有裂隙角度影响试件的扩展路径和分形维数，角度增加与更高的分形维数相关且对压缩峰值应力有正向影响。该研究为深部工程爆破参数设计提供了关于裂隙岩石在动载下复杂断裂行为的有价值见解。它还为预防与岩石失稳相关的灾害提供了关键知识，因此在岩石力学与工程领域具有重要的理论和实际意义。
