1. College of Resource, Shandong University of Science and Technology, Tai’an, Shandong 271000, China
2. National Engineering Laboratory for Coalmine Backfilling Mining, Shandong University of Science and Technology, Tai’an, Shandong 271000, China
3. Shandong Energy Group Co., Ltd., Ji’nan, Shandong 250100, China
4. College of Finance and Economics, Shandong University of Science and Technology, Tai’an, Shandong 271000, China