1. Senior Lecturer, Dept. of Geotechnics and Transportation, Faculty of Civil Engineering, Univ. of Teknologi Malaysia, UTM Skudai, 81310 Johor Bahru, Malaysia.
2. Postgraduate Student, Dept. of Geotechnics and Transportation, Faculty of Civil Engineering, Univ. of Teknologi Malaysia, UTM Skudai, 81310 Johor Bahru, Malaysia (corresponding author).
3. Professor, Dept. of Geotechnics and Transportation, Faculty of Civil Engineering, Univ. of Teknologi Malaysia, UTM Skudai, 81310 Johor Bahru, Malaysia.