How can accumulated damage lead to a violent rock failure? An innovative experimental study for rockburst

Abstract

Rockburst is characterised by a violent ejection of rock fragments from the free face of an underground excavation. This is a serious problem which can kill people, damage equipment and/or cause production loss. As mining operations are being taking place in deeper rock masses, the propensity for rockburst increases due to the significant increase of overburden pressure. In order to understand and provide a deeper insight into the occurrence of rockburst, a number of thick-walled hollow cylinder rockburst tests using granite under a variety of stress paths were conducted. The recently developed University of Adelaide Rockburst Test (UART) apparatus was used to replicate the stress conditions of rockburst at the laboratory scale. Additionally, acoustic emission (AE) responses of each test were recorded to enable qualitative and quantitative damage assessment of the phenomenon. To explain the overall mechanical behaviour of the rocks leading to rockburst, the results were analysed by time-domain responses of AE signals. The effects of in-situ pressure on the damage evolution during rockburst was investigated. According to the damage evolution rates, a new rockburst proneness criterion was also proposed. Based on the detailed analyses of the tests, conclusions are drawn on the effectiveness of the method as well as providing more insight into the mechanism of laboratory scale rockburst.