Rockburst Risk Analysis During High-Hard Roof Breaking in Deep Mines
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Original Paper
Rockburst Risk Analysis During High-Hard Roof Breaking in Deep Mines Qiming Zhang,1,2 Enyuan Wang,1,2,4 Xiaojun Feng,1,2,4 Yue Niu,1,2 Muhammad Ali,3 Song Lin,1,2 and Hao Wang1,2 Received 28 December 2019; accepted 19 March 2020
Mining operations continue to advance to greater depths to address the demand and supply of coal. However, deep mining occurs in complex and dangerous environments where mines are often subject to rockbursts induced by high-hard roof breaking (HHRB). Here, we use the #2233 working face of the Hengda coal mine as a case study to investigate the mechanism of HHRB-induced rockbursts by means of stress, electromagnetic radiation (EMR) and hydraulic support resistance. We propose an elastoplastic plate theory model to study the relationship between impact load energy and maximum roof deformation and verify the dynamic evolution of rockbursts generated by HHRB by FLAC3D numerical modeling. The results show that rockbursts are more likely to occur when the coal-rock mass under high static stress conditions is subjected to superposition of continuous dynamic stress. This is accompanied by an abrupt increase in stress, increase in hydraulic support resistance, accumulation of strain energy that is not easily dissipated and a decrease in EMR intensity. The peak dynamic stress value determines the deformation mode of the elastoplastic plate model, and the impact damage behavior of the coal-rock mass is the most apparent, whereas the maximum deformation displacement lags slightly behind the arrival time of the peak stress. The occurrence of rockbursts is accelerated by long-term and high-amplitude dynamic disturbances. KEY WORDS: Rockburst, High-hard roof breaking, Dynamic–static stress, Elastoplastic model, Numerical simulation.
INTRODUCTION Rockbursts pose a serious threat to the safety and efficiency of coal mining (Wang and Park 2001; He et al. 2010; Li et al. 2012; Keneti and Sainsbury 2018; 1
Key Laboratory of Gas and Fire Control for Coal Mines, China University of Mining and Technology, Xuzhou 221116, China. 2 School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China. 3 Department of Mining Engineering, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan. 4 To whom correspondence should be addressed; e-mail: [email protected], [email protected]
Wang et al. 2018; Feng et al. 2019; Niu et al. 2019). Previous studies have addressed the rockburst process and its prevention; however, the rockburst mechanism remains poorly understood and dynamic rockburst disasters are anticipated to threaten the safety of coal mine production for an unforeseeable amount of time in the future (Konicek et al. 2013; Li et al. 2019a, b; Faradonbeh and Taheri 2019). In addition, increased mining depth and intensity affect clearly the evolution of rockbursts by dynamic disturbances, such as high-hard roof breaking (HHRB). In HHRB, the roof is located high above the mining coal seam, the rock stratum is thic
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