台湾海底隧道之接头与管段变化研析及对策

Evaluation and Countermeasures for the Joints and Tunnel Structure of Taiwan's Undersea Immersed Tunnel

台湾唯一之海底隧道系采沉埋方式施工,该隧道不仅处于具高度盐份腐蚀之不利环境,且位于软弱地盘上。于营运二十余年后,轻微异状已有显现,如管段接头锈蚀、管体渗漏及管体裂损等异状。上述异状可能为接头构件变形、管体变位/变形及结构劣化等影响隧道安全之前兆,甚至降低其耐震能力;因该隧道肩负港区及区域经济发展之运输重任,如何藉由整体性体检进行安全评估及研订适当之维护补强对策,为计划执行重点;故本文将说明隧道接头、结构体等隧道重要构件之检测调查(如地球物理、钢筋腐蚀、裂缝深度、氯离子试验、防蚀电位、接头防水等项目)、数值分析及自动化监测(接缝计、单元沉陷仪、结构倾斜仪、电位计等)等综合评估结果及维护补强对策,以提供工程界日后参考。

The Kaohsiung cross-harbor tunnel was built using the caisson box sinking method and is the only Taiwan' s undersea tunnel. The construction of the tunnel faced extreme conditions such as sea salt which may result in corrosion of the tunnel structure, and also it is situated on weak seabed. However, after 20years of usage, the tunnel had begun to show slight damages, for example, joint corrosion, leakage and cracks in the tunnel etc. These damages to the tunnel may cause situation such as part of the joint displacement, structure inclination and causing detrimental effect to the o-verall structure of the tunnel, and hence, greatly reduce the tunnel's ability due to earthquake. The tunnel is the main economic link of southern Taiwan. Therefore, the main point is to take into account all the reasons above, do an overall checkup on the tunnel and come out with a suitable proposal for any necessary reparation works. This report will explain matters related to the maintenance of tunnel joints, structure and other important points of a tunnel. It will also touch on the numerical analysis, the automated monitoring tools, and suggestion for any reparation works.