Proceedings of the
9th International Symposium for Geotechnical Safety and Risk (ISGSR)
25 – 28 August 2025, Oslo, Norway
Editors: Zhongqiang Liu, Jian Dai and Kate Robinson
Investigation of the Impact of Geological Uncertainty on the Risk of Subsea Tunnel Crossing a Fault Zone
1Department of Geotechnical Engineering, Tongji University, China.
2Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, China.
3Qingdao Guoxin Jiaozhou Bay Second Submarine Tunnel Co., Ltd, China.
ABSTRACT
Subsea tunnels crossing fault zones face significant uncertainties in various parameters, which pose substantial adverse effects on excavation risks. In this paper. firstly, a statistical analysis of six parameters in the fault zones of the Qingdao Jiaozhou Bay Second Subsea Tunnel (hereinafter referred to as "Qingdao Second Tunnel")was conducted, including seawater depth, tunnel burial depth, surrounding rock unit weight, elastic modulus, cohesion, and friction angle. Then, comprehensive load index and resistance index were proposed to quantitatively evaluate the magnitude and uncertainty of load and resistance. Meanwhile, their distributions and correlations were also examined.Subsequently, reliability analysis was carried out via a Kriging-based Response Surface Method (RSM) using a 3D numerical model validatedwith field data. Results indicate that the failure probability of the Qingdao Second Tunnel crossing fault zonesis0.3%.Finally, five risk grades were divided based on the maximum crown settlementof tunnel, which can be referenced in engineering risk management.
Keywords: Subsea tunnel, Fault zone, Kriging-based RSM, Risk, Reliability analysis, Distribution, Correlation.
