1. Graduate Assistant, Dept. of Civil Engineering, Case Western Reserve Univ., 2104 Adelbert Rd., Bingham 269, Cleveland, OH 44106-7201.
2. Graduate Assistant, Dept. of Civil Engineering, Case Western Reserve Univ., 2104 Adelbert Rd., Bingham 271, Cleveland, OH 44106-7201.
3. Professor, Dept. of Geological Engineering, Chang’an Univ., Xi’an, China.
4. Professor, Dept. of Civil Engineering, Case Western Reserve Univ., 2104 Adelbert Rd., Bingham 206, Cleveland, OH 44106-7201 (corresponding author).