1. Ph.D. Student, Dept. of Civil Engineering, Univ. of New Mexico, MSC01 1070, Albuquerque, NM 87131 (corresponding author).
2. Geotechnical Engineer, Arias & Associates, Inc., 142 Chula Vista, San Antonio, TX 78232.
3. Professor, Dept. of Civil Engineering, Univ. of New Mexico, MSC01 1070, Albuquerque, NM 87131.