1. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, P. R. China
2. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology at Beijing, Beijing 100083, P. R. China
3. Key Laboratory of Energy Engineering Safety and Disaster Mechanics, Ministry of Education Sichuan University, Chengdu 610065, P. R. China