1. Jiangsu Mineral Resources and Geological Design and Research Institute, China National Administration of Coal Geology, Xuzhou, Jiangsu 221006, China
2. Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education, China University of Mining and Technology, Xuzhou, Jiangsu 221008, China
3. School of Civil Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu 221018, China
4. School of Safety and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China