ZHANG, YUBAO, COLLEGE OF ENERGY AND MINING ENGINEERING, SHANDONG UNIVERSITY OF SCIENCE AND TECHNOLOGY, QINGDAO 266590, CHINA / STATE KEY LABORATORY OF MINING DISASTER PREVENTION AND CONTROL CO-FOUNDED BY SHANDONG PROVINCE AND THE MINISTRY OF SCIENCE AND TECHNOLOGY, SHANDONG UNIVERSITY OF SCIENCE AND TECHNOLOGY, QINGDAO 266590, CHINA, China