1. Associate Professor, College of Earth Sciences and Engineering, North China Univ. of Water Resources and Electric Power, Zhengzhou, Henan 450000, China (corresponding author).
2. Graduate Assistant, College of Earth Sciences and Engineering, North China Univ. of Water Resources and Electric Power, Zhengzhou, Henan 450000, China.
3. Professor, College of Civil Engineering, Tsinghua Univ., Beijing 10084, China.
4. Professor, College of Earth Sciences and Engineering, North China Univ. of Water Resources and Electric Power, Zhengzhou, Henan 450000, China.