1. School of Civil Engineering, Inner Mongolia University of Science and Technology, Baotou Inner Mongolia 014010, China
2. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou 221116, China
3. School of Mining and Coal, Inner Mongolia University of Science and Technology, Baotou Inner Mongolia 014010, China
4. School of Mining Technology, Taiyuan University of Technology, Taiyuan 030024, China