Seismic response analysis and resilience study of Qingdao 2nd submarine tunnel using the finite element method

Abstract

Earthquakes, as considered a highly destructive and unpredictable natural disaster that poses significant challenges for engineers designing underground structures. Incorporating seismic considerations is important to ensure the safety and stability of such structures. Therefore, it is crucial to analyze the response of tunnels to earthquakes and establish an evaluation index for their resilience, which would help guide projects toward improved safety. In this paper, we use numerical simulations to study the seismic impact on the Qingdao 2nd Submarine Tunnel according to different lining thicknesses (25-75 cm) and varying stratum conditions. Through adjustments to lining thickness and stratum conditions, a total of 30 numerical simulation experiments are conducted. These experiments contribute to the creation of the resilience evaluation index. The results of the study indicate the following trends: 1. Increasing lining thickness reduces the stress and deformation along the lining, though the effect stabilizes around 45-cm thickness. 2. Poor surrounding rock conditions lead to increased stress and deformation along the lining, especially near fault fracture zones. 3. The culmination of the study involves the creation of a resilience evaluation index, which serves as a practical guidance for tunnel construction in real-world projects.