胶州湾第二海底隧道穿越活动断层抗错断结构方案研究

Antidislocation Structure Design of Jiaozhou Bay Second Subsea Tunnel Crossing an Active Fault

为保证海底隧道在断层错动作用下的结构安全,依托胶州湾第二海底隧道工程,对隧道穿越最大位错量为0.49 m的沧口断裂段落进行衬砌结构设计,提出扩大断面和多孔脆性材料填充2种方案。采用有限元数值模拟方法对2种方案衬砌结构的变形与受力特点进行分析,并综合对比2种方案的衬砌结构受力情况、扩挖量和施工难易度,最终推荐采用柔性连接结合多孔脆性材料填充的抗错断结构设计方案。该方案在减小开挖量、未明显增加施工难度的同时,克服了扩大断面方案二次衬砌在断层错动作用下易破坏的问题,可保证止水构造正常发挥作用,提升海底隧道衬砌结构在断层错动下的安全性。

Based on the Jiaozhou Bay Second Subsea Tunnel project,an antidislocation structure of the tunnel crossing the Cangkou fault subject to a maximum dislocation of 0.49 m is designed.An optimal structure design is proposed considering the serious weakening of the waterproof performance induced by the failure of the tunnel lining.The characteristics of deformation and stresses of the secondary lining′s large cross-section scheme and the porous brittle buffer material scheme are compared using the finite element method.Furthermore,the excavation quantities and the construction difficulties are compared,and the optimal design scheme of an antidislocation structure with flexible joints and porous brittle material buffering is finally selected.In addition to reducing the amount of excavation work and eliminating construction difficulty,the optimal scheme addresses the issue of the secondary lining of the traditional expanded excavation method,which is prone to devastating damage under the action of fault dislocation.This ensures the normal functionality of the water stop structure,and improves the safety of the subsea tunnel under active fault dislocation.