Macro-meso failure behavior of pre-flawed hollow-cylinder granite under multi-level cyclic loads: Insights from acoustic emission and post-test CT scanning. (December 2021)

• Record Type: Journal Article
• Authors: Wang, Y.; Han, J.Q.; Song, Z.Y.; Zhu, C.
• Is Part Of: Engineering fracture mechanics. Volume 258(2021)
• Publication Date: 2021-12
• Subjects: Cyclic loads -- Pre-flawed granite -- Acoustic emission -- Failure mechanism -- Crack propagation; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2021.108074
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: The macro-meso failure mechanism of pre-flaw hollow-cylinder under cyclic loads was revealed. Flaw angle influences the rock deformation, lifetime, AE activities and crack pattern. A damage evolution model was proposed by AE b value to describe three-phase damage propagation. Communication degree and crack network is relatively large for rock having a high flaw angle. Abstract: The structural deterioration and associated macro-meso fracture behaviors of granite containing crack-like and hole-like flaws subjected to multi-level cyclic loads are studied in this paper. The tested samples were prepared with a hollow hole of 15 mm and different flaw approach angles of 10°, 30°, 50° and 70°, respectively. The real-time AE monitoring combined with post-test CT scanning was employed to reveal the effects of flaw angle on the strength, deformation, AE activities and crack network pattern. Results show that the communication of the crack network and hole controls the rock volumetric deformation and the final failure modes. The output AE activities are influenced by the flaw arrangement. The progressive crack unstable propagation is much more severe for rock with low flaw angle and the recorded AE count/energy curves present multi-stage skips. The AE b value shows a first increase and then a decrease pattern. A damage evolution model was proposed by AE b value, the first fast and then steady increase and the final abrupt increase of accumulative damage can be well described. The complexity of crack network is larger for rock has high flaw angle, and the communication of crack and hole wall is severe accordingly. It is suggested that the failure of the pre-flawed hollow-cylinder granite is the interaction of crack coalescence and hole spalling.