Rock burst initiation and precursors in a model specimen based on acoustic emission and infrared monitoring

• Published in: Arabian journal of geosciences Vol. 15; no. 4
• Main Authors: Lin, Manqing, Gao, Chengcheng, Xia, Yuanyou, Zhang, Dianji, Liu, Xiqi, Liang, Xiaoshuai
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.02.2022; Springer Nature B.V
• Subjects: Accumulation; Acoustic emission; Acoustics; Anomalies; Dredging; Earth and Environmental Science; Earth science; Earth Sciences; Emergency warning programs; Emission analysis; Energy; Energy release rate; Evolution; Excavation; Failure analysis; Failure mechanisms; Failure modes; Gradients; I.R. radiation; Image enhancement; Infrared analysis; Infrared radiation; Malformations; Mechanical properties; Mechanical unloading; Model testing; Monitoring; Monitoring methods; Original Paper; Precursors; Radiation; Rock; Rock masses; Rockbursts; Rocks; Rupture; Rupturing; Scale models; Stress; Temperature; Theoretical analysis; Unloading; Warning systems; Infrared features; Acoustic emission; Rock burst; Stress gradient; Precursory comparison
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-09423-y

Theoretical analysis of the mechanical factors that cause the different failure modes of surrounding rocks laboratorial model tests was carried out under four different stress gradients considering the stress environment of a high ground stress rock mass and the stress path of surrounding rocks during excavation unloading. The aim is to study the rockburst failure mechanisms and energy evolution trends under different stress gradient loadings. Loading and unloading tests of large-scale model specimens with rock burst tendency under gradient stress were conducted with a rock burst loading device. The changes in the acoustic emission (AE) and infrared anomalies of the specimens under loading were captured. On the basis of the test results, we quantitatively analyzed the AE energy change of the model specimen during loading and used the obtained thermal images for image enhancement processing and energy evolution analysis. The energy evolution characteristics of the whole loading process were analyzed by AE methods and infrared monitoring methods in time and space. A timing comparison of the AE ring count precursor and infrared temperature time curve precursor was made. The results show that the damage evolution periods of the specimens under uniform loading, low-gradient loading, and high-gradient loading differed. With an increase in the stress gradient, the duration of the energy accumulation stage is increased, and the duration of the dissipation stage shortened, and the energy release rate is increased. The accumulation-dissipation-release stages cause that the rock burst intensity increases with the loading stress gradient. The AE characteristics and infrared radiation spatiotemporal evolution characteristics of the specimen are well synchronized during the process of rock burst initiation under the tested stress gradients. Before the main rupture of the model specimen occurs, the site of the specimen about to rupture shows the precursor of acoustic emission parameters, the precursor of the maximum temperature–time curve, and the precursor of thermal image abnormality. This experimental study clarifies the influence mechanism of the stress gradient distribution in the surrounding rock and provides theoretical guidance for the establishment of disaster warning systems for deep engineering.