1. Research Fellow, Centre for Geomechanics and Railway Engineering (CGRE), ARC Training Centre for Advanced Technologies in Rail Track Infrastructure (ITTC-Rail), Univ. of Wollongong Australia, Wollongong, NSW 2522, Australia. ORCID: .
2. Distinguished Professor of Civil Engineering, Research Director, Centre for Geomechanics and Railway Engineering (CGRE), ARC Training Centre for Advanced Technologies in Rail Track Infrastructure (ITTC-Rail), Univ. of Wollongong Australia, Wollongong, NSW 2522, Australia (corresponding author).