DYNAMIC RESPONSE AND SAFETY DESIGN ANALYSIS OF SUBMERGED FLOATING TUNNEL WITH ANCHOR-CABLES DUE TO CABLE LOSS

Aiming at the structural characteristics of the submerged floating tunnel (SFT) with anchor-cables, a technical framework is proposed for dynamic response analysis and structural safety design due to the sudden anchor-cable loss. The initial state of the SFT under the tube residual buoyancy and anchor-cable pre-tensions prior to the cable loss is established within ABAQUS finite element software. Then the dynamic response analysis of the single anchor-cable abruptly broken in the mid-span cross-section of the SFT is carried out by finite element program. Obtained are the maximum value of the response during the vibration phrase as well as the internal force redistribution of the remaining structure after the anchor-cable fails. Dynamic amplification factor (DAF) and dynamic coefficient (DC) are respectively used to evaluate the impact effects on the remaining structure due to the cable loss. Furthermore, a simplified structural response analysis method is proposed upon DAF and DC, and the results are compared with the dynamic calculations. The results show that applying the pretensions to some of the anchor-cables makes the initial state of the SFT more reasonable under the dead load. The structural vibration caused by local anchor-cable loss is significant, resulting in larger deformation of the SFT tube near the cable loss cross-section. It is rational to take the DAF=2.0 for the structural safety analysis of the displacement and bending moment of the SFT tube from the cable loss response. By taking the DC=1.8 to predict the maximum tensions of the remaining anchor-cables during the cable loss process, the safety reserve is higher. © 2023 Tsinghua University. All rights reserved.