1. Research Associate, Geomechanics Research Group, Lassonde Institute, Civil Engineering Dept., Univ. of Toronto, Toronto, ON, Canada M5S 1A4.
2. Ph.D. Student, Geomechanics Research Group, Lassonde Institute, Civil Engineering Dept., Univ. of Toronto, Toronto, ON, Canada M5S 1A4.
3. Professor, Dept. of Engineering, Queen Mary Univ. of London, London E1 4NS, U.K.
4. Assistant Professor, Geomechanics Research Group, Lassonde Institute, Civil Engineering Dept., Univ. of Toronto, Toronto, ON, Canada M5S 1A4 (corresponding author).