1. Senior Lecturer, Faculty of Engineering and Surveying, Univ. of Southern Queensland, QLD 4350, Australia (corresponding author).
2. Senior Lecturer, Center for Geotechnical and Materials Modelling, The Univ. of Newcastle, NSW 2308, Australia.
3. Associate Professor, Center for Geotechnical and Materials Modelling, The Univ. of Newcastle, NSW 2308, Australia.
4. Professor, Center for Geotechnical and Materials Modelling, The Univ. of Newcastle, NSW 2308, Australia.