[1] Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong University of Science and Technology, Qingdao,266 590, China
[2] State Key Laboratory Breeding Base for Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao,266 590, China
[3] Department of Underground Space, School of Civil and Hydraulic Engineering, Shandong University, Jinan,250 061, China