1. Urban and Environmental Science; Bin zhou University; Bin zhou Shandong 256603 China
2. Key Lab of Mine Disaster Prevention and Control; College of Resource and Environmental Engineering, Shandong University of Science and Technology; Qingdao 266590 China
3. Key Lab of Gas and Fire Control for Coal Mines of Ministry of Education; Faculty of Safety Engineering, China University of Mining and Technology; Xuzhou Jiangsu 221116 China