1. School of Civil & Architecture Engineering, Zhongyuan University of Technology, Zhengzhou 450007, Henan, China
2. School of Mechanics & Civil Engineering, China University of Mining and Technology, Beijing 100083, China
3. State Key Laboratory for Geomechanics and Deep Underground Engineering, Beijing 100083, China
4. Department of Civil Environmental and Geo-Engineering, University of Minnesota, Minneapolis, MN, USA