文献类型：期刊文献

英文题名：Experimental Investigation on Fracture Behaviors and Crack Propagation Characteristics of Granite Under Cyclic Loading and Unloading

作者：Lin, Zhongqin[1,2,3];Xue, Fei[1,2];Wu, Xuezhen[3];Zhou, Xin[1,2]

机构：[1]Shaoxing Univ, State Key Lab Intelligent Deep Met Min & Equipment, Shaoxing 312000, Peoples R China;[2]Shaoxing Univ, Sch Civil Engn, Zhejiang Key Lab Rock Mech & Geohazards, Shaoxing 312000, Peoples R China;[3]Fuzhou Univ, Coll Civil Engn, Fuzhou 350108, Peoples R China

年份：2025

外文期刊名：ROCK MECHANICS AND ROCK ENGINEERING

收录：SCI-EXPANDED(收录号：WOS:001545571800001)、、EI(收录号：20253218964466)、Scopus(收录号：2-s2.0-105012735312)、WOS

基金：The authors would like to acknowledge the financial support for this study provided by the National Natural Science Foundation of China (Grant No. 52104094, No. 52179098, and No. 41907251), the China Postdoctoral Science Foundation (2022M721997) and the National Key Research and Development Program Young Scientist Project (2024YFC2911000).

语种：英文

外文关键词：Cyclic loading and unloading; Fracture surface topography; Crack propagation; Acoustic emission; Digital image correlation

外文摘要：This study investigates the fracture behaviors and crack propagation characteristics of granite under cyclic loading and unloading. Semi-circular bending (SCB) specimens were subjected to three-point bending tests integrated with acoustic emission (AE) monitoring, 3D scanning, and digital image correlation (DIC) technologies. The experimental protocols included static loading, tiered constant amplitude (TCA) cyclic loading, and variable amplitude (VA) cyclic loading. The results show that cyclic loading significantly influences fracture toughness by modifying the internal microstructure of granite. During cyclic loading and unloading, microcracks repeatedly open and close, leading to a denser microstructure and increased stiffness. 3D scanning analysis revealed that cyclic loading produces rougher and more tortuous fracture surfaces and trajectories as compared to static loading. AE activity under VA cyclic loading indicated the generation of numerous microcracks and the formation of a larger microcrack zone with lower energy release, whereas TCA cyclic loading was characterized by lower-frequency AE signals. This suggests that incomplete unloading and shorter loading durations in TCA conditions deteriorate the intergranular interlocking capacity of mineral grains, promoting intergranular crack formation. DIC analysis demonstrated that VA cyclic loading facilitates microcrack development, resulting in increased microcrack extension lengths and a larger fracture process zone (FPZ) at peak load. Furthermore, the higher ratio of normalized crack mouth opening displacement (CMOD), normalized crack tip opening displacement (CTOD), and displacement jumps during the cyclic loading and unloading process of TCA conditions indicate greater plastic deformation and cumulative damage. This work enhances the understanding of how cyclic load affects rock fracture characteristics and elucidates the mechanisms underlying fatigue failure in granite, providing valuable insights for the design and assessment of rock engineering structures subjected to cyclic stresses.