1. Lecturer, College of Mining and Safety Engineering, Shandong Univ. of Science and Technology, Qingdao 266590, China; Ph.D student, School of Resources and Safety Engineering, Central South Univ., Changsha, Hunan Province 410083, China.
2. Professor, School of Resources and Safety Engineering, Central South Univ., Changsha, Hunan Province 410083, China.
3. Associate Professor, Earth Mechanics Institute, Dept. of Mining Engineering, Colorado School of Mines, Golden, CO 80401.
4. Master’s Degree Student, School of Resources and Safety Engineering, Central South Univ., Changsha, Hunan Province 410083, China.
5. Professor, School of Resources and Safety Engineering, Central South Univ., Changsha, Hunan Province 410083, China (corresponding author).
6. Associate Professor, School of Resources and Safety Engineering, Central South Univ., Changsha, Hunan 410083, China.