1. College of Resource and Environmental Engineering, Inner Mongolia University of Technology, Hohhot 010051, China
2. Inner Mongolia Engineering Research Center of Geological Technology and Geotechnical Engineering, Inner Mongolia University of Technology, Hohhot 010051, China
3. Inner Mongolia Mining Development Limited Liability Company, Hohhot 010051, China
4. Key Laboratory of Coalbed Methane Resource & Reservoir Formation Process, Ministry of Education, China University of Mining & Technology, Xuzhou 221008, China