Research on acoustic emission characteristics of marble damaged by pre-peak unloading. Issue 3 (October 2020)

• Record Type: Journal Article
• Authors: Zhu, Zihan; Yu, Liyuan; Li, Jinglong; Su, Haijian; Zhang, Zhanqun; Zhang, Jing
• Is Part Of: IOP conference series. Volume 570:Issue 3(2020)
• Publication Date: 2020-10
• Subjects: Earth sciences -- Periodicals; Environmental sciences -- Congresses; Environmental sciences -- Periodicals; 550.5
• DOI: 10.1088/1755-1315/570/3/032050
• Languages: English
• ISSNs: 1755-1307

Abstract

Abstract: Excavation of the tunnel in high geo-stress environment induces strong stress redistribution, resulting in unloading damage of surrounding rock. The damaged surrounding rock is the main load bearing body for the tunnel in the running period. Therefore, it is necessary to study the acoustic emission (AE) characteristics during the reloading of damaged rock. The marble was chosen to manufacture specimens in this paper, and we designed pre-peak unloading tests. Confining pressure of pre-peak unloading test is 15MPa and three types of unloading point (70MPa, 80MPa and 90MPa). The laboratory tests are made for studying AE characteristics of damaged marble samples by using MTS816 and acoustic emission instrument AE21C. The test results showed that as the unloading point increases, the peak strength of the rock decreases with increased corresponding peak strain. Rock failure mode gradually changed from brittle failure to quasi-brittle failure; Accumulated AE count is negatively correlated with the unloading point, and the AE quiet period is positively correlated with the unloading point. The evolution of b -value is divided into three phases: slow increase, sharp increase and rapid decrease. The findings of this research can provide the significance for selecting mechanical parameters of the surrounding rock and optimizing support scheme.