1. Key Laboratory of Deep Coal Resource Mining (Ministry of Education), School of Mines, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
2. Centre of Rockburst Prevention Research, Shandong Energy Group, Jinan, Shandong 250014, China
3. Baodian Coal Mine, Shandong Energy Group, Zoucheng, Shandong 273513, China
4. School of Civil Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, China