1. Research Fellow, Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia; Senior Lecturer, Dept. of Civil Engineering, Univ. of Engineering and Technology Lahore, Punjab 54890, Pakistan.
2. Distinguished Professor and Director of Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia (corresponding author).