1. State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
2. College of Resources and Environmental Science, Chongqing University, Chongqing 400044, China
3. Key Laboratory of Shale Gas Exploration, Ministry of Land and Resources, Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China
4. School of Geosciences and Info-Physics, Central South University, Changsha 410012, China