1. Professor, Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong Univ., Chengdu 610031, China.
2. Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong Univ., Chengdu 610031, China.
3. Professor, School of Civil Engineering, Shandong Univ., Jinan, Shandong 250061, China (corresponding author).
4. Professor, State Key Lab Coal Resources and Safe Mines, China Univ. of Mining and Technology, School of Mines, Xuzhou 221116, Jiangsu, China.