1. M.Sc. Student, School of Engineering, Deakin Univ., Geelong, VIC 3217, Australia.
2. Lecturer, School of Engineering, Deakin Univ., Geelong, VIC 3217, Australia (corresponding author).
3. Technical Principal, SMEC Australia, 74 Hunter St., Newcastle, NSW 2300, Australia.
4. Professor, Centre for Geotechnical and Materials Modelling, Univ. of Newcastle, Callaghan, NSW 2308, Australia.