1. Department of Civil Engineering, University of Bristol, Bristol, UK.
2. Department of Engineering, University of Cambridge, Cambridge, UK.
3. Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Dublin, Ireland.
4. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, P. R. China.
5. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, P. R. China; University of Chinese Academy of Sciences, Beijing, P. R. China.