Abstract
Rock burst is a violent release of energy stored in the rock mass, which has been the focus of metal mine engineers. It gradually becomes a serious threat to both the mine’s workers and equipment. Rock burst risk assessment is a key issue in the prevention of rock burst. Based on the microseismic method for rock burst risk assessment that is used in tunnels, this paper presents a method of rock burst risk assessment for metal mines combining a simplified probability function and principal component analysis (PCA). Specifically, the size and details of key monitoring area and risk assessment units are determined according to the distribution of the fracture and driving stress during deep mining process. Based on the correlation analysis, six microseismic parameters are selected to be used for rock burst risk assessment. Simple linear functions are temporarily used to construct probability functions of each parameter before enough rock burst cases are collected. The method has been successfully used in the deep mining section of the Ashele Copper Mine (approximately 1000 m deep). Additionally, among various microseismic indicators, the energy release rate and cumulative energy are the greatest contributors to rock burst of different intensities. Therefore, the proposed method in this paper provides an important reference for the prevention and control of rock burst in metal mines.
Highlights
High stress usually occurs in deep underground engineering
Rock burst have been observed in mines [4, 5], tunnels [6], hydraulic engineering projects [7, 8], and other forms of underground engineering projects and has become a worldwide problem. e number of rock burst cases is reported in the tunnels of Norway [9], in hydraulic engineering projects in China [10], and in the deep mines of China [11], South Africa [12], and Canada [13]
The occurrence of rock burst should be attributed to all the microseismic indicators. erefore, it should be noted that the rock burst risk assessment should take into account the microseismic indicators according to the correlation analysis. e formula which involves multiple indicators is shown as follows: n
Summary
High stress usually occurs in deep underground engineering. When the actual stress exceeds the rock mass strength, some brittle failure may occur, accompanied with the release of a large quantity of energy [1,2,3]. is phenomenon is named rock burst. E latter assesses rock burst risk dynamically according to detailed conditions and information gained from monitoring the mining process and takes timely rock burst control measures. Many scholars presented risk assessment methods and rock burst indicators after studying the law of microseismicity in the process of construction [37]. Considering the production capacity requirement, multiple stopes at different levels need to be mined at the same time, which leads to the coexistence of numerous goafs in a metal mine In such conditions, it is difficult for engineers to collect useful information during the rock burst development process. Considering the differences between the metal mines and the tunnels, such as nonlinearity, simultaneous mining in multimiddle section and multiple stopes and complex layout of shaft and roadway, a specific rock burst risk assessment method is attempted in a metal mine. It may provide a reference for determining potential rock burst areas
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