1. Research Academic (Australian Research Council), Centre for Geomechanics and Railway Engineering School of Civil, Mining and Environmental Engineering, Faculty of Engineering and Information Sciences, Univ. of Wollongong, Wollongong City, NSW 2522, Australia (corresponding author).
2. Lecturer, School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology, Univ. of Technology Sydney, City Campus, Ultimo, NSW 2007, Australia.