1. Ph.D. Student, State Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong Univ., Beijing 100044, China.
2. Professor, State Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong Univ., Beijing 100044, China (corresponding author).
3. Professor, State Key Laboratory of Hydroscience and Engineering, Tsinghua Univ., Beijing 100084, China.