1. Associate Professor, Faculty of Engineering, China Univ. of Geosciences, Wuhan 430074, PR China (corresponding author).
2. Postgraduate, Faculty of Engineering, China Univ. of Geosciences, Wuhan 430074, PR China.
3. Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., Houghton, MI 49931-1295.
4. Associate Professor, Faculty of Engineering, China Univ. of Geosciences, Wuhan 430074, PR China.