1. Key Laboratory of Coal Methane and Fire Control, Ministry of Education, China University of Mining and Technology, Xuzhou, Jiangsu, China. E-mail: wdmcumt@gmail.com
2. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, Jiangsu, China
3. Xuzhou Anyun Coal Mine Safety Co. Ltd, Xuzhou, Jiangsu, China
4. Guizhou Coal Mine Design and Geological Disasters Control Engineering Co. Ltd, Guiyang, Guizhou, China