1. Buchanan Chair Professor, Zachry Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-3136 (corresponding author).
2. Project Professional, Fugro Consultants, 6100 Hillcroft, Houston, TX 77081.
3. Research Geotechnical Engineer, FHWA, Office of Infrastructure Research and Development, 6300 Georgetown Pike, Mclean, VA 22101.
4. Ph.D. Student, Zachry Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-3136.