1. Ph.D. Student, School of Civil and Environmental Engineering, Oklahoma State Univ., Stillwater, OK 74078.
2. Professor, School of Civil and Environmental Engineering, Oklahoma State Univ., Stillwater, OK 74078 (corresponding author).
3. Geotechnical Branch Manager, Oklahoma Dept. of Transportation, 5201 N.E. 122nd St., Bldg. 4011, Edmond, OK 73013.
4. Geotechnical Engineer, Oklahoma Dept. of Transportation, 5201 N.E. 122nd St., Bldg. 4011, Edmond, OK 73013.