1. Graduate Student, Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA 70803.
2. Edwin B. and Norma S. McNeil Distinguished Professor, Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA 70803 (corresponding author).
3. Professor, Institute of Geotechnical Engineering, Xi’an Univ. of Technology, Xi’an, Shaanxi 710048, China.