Mechanical behavior and failure process of hard rock with rock bridge under uniaxial compression test

• Published in: Lithosphere Vol. 2022; no. Special 11
• Main Authors: Zhang Yan, Zhang Yan, Chen Guoqing, Chen Guoqing, Gao Yaohui, Gao Yaohui, Xu Yitian, Xu Yitian, Liu Ding, Liu Ding
• Format: Journal Article
• Language: English
• Published: GeoScienceWorld 2022
• Subjects: acoustical emissions; Asia; brittle deformation; Changsha China; China; compression; deformation; Engineering geology; experimental studies; failures; Far East; fractures; granites; Hunan China; igneous rocks; joints; laboratory studies; pillars; plutonic rocks; rock bridges; rock masses; rock mechanics; uniaxial tests
• ISSN: 1941-8264; 1947-4253
• DOI: 10.2113/2022/1492868

The mechanical properties of rock mass are mostly controlled by the structural plane. Rock bridge has an important effect on the failure and stability of rock mass with structural plane. In this paper, the uniaxial compression test of hard rock containing rock bridge is carried out, accompanied by acoustic emission (AE) and high-speed video monitoring. Within the scope of this study, the results show that the uniaxial compressive strength (UCS) of sample with rock bridge increases with the rock bridge length. Under the same stress condition before peak, the strain of the sample decreases with the increase of the rock bridge length (RBL). Under the influence of stress concentration, the cracking of the sample starts from the prefabricated crack tip. The peak AE count of the sample decreases with the increase of RBL. The AE cumulative energy of the sample increases with the increase of RBL. The number of cracks in the sample before the peak is small, and the rapid increase of cracks is mainly concentrated in the main fracturing stage after the peak, while after reaching the residual stage, the increase rate of various types of microcracks in the sample is relatively slow. The numerical simulation results show that the number of all kinds of cracks in the sample before the peak is small, and the number of tensile cracks in the sample is very close to the total number of cracks under different RBLs. With the increase of RBL, the tensile/shear crack ratio decreases. The internal cracks of the sample are mainly concentrated at the peak stress and postpeak stage. The research results of this paper are of great significance to the engineering excavation and safe construction of jointed rock mass engineering.