A connecting passage of the Metro Line 18 in Shanghai was under construction in a sand layer featuring high fine content and a high level of confined water head. During the tunnel construction, an incident of water and soil gushing through the freezing holes resulted in large settlement and damage to the tunnel linings. The remedial measures were then carried out to prevent the incident and to strengthen the damaged tunnel linings. This paper analyzes the reasons for the water and soil gushing, the damage to the tunnels, and the effect of the remedial measures. The main reason for the incident was water and sand penetration through the gap between the freezing pipes and the borehole orifice pipes due to the high water pressure outside the tunnels. The monitoring results indicate that the grouting and the lining reinforcement with reinforced steel ring effectively improved the stability of the tunnel structures. This case study provides practical experience and guidance for similar tunnelling projects in the future to mitigate the risk of water and soil gushing.

上海地铁18号线的连接通道正在建设中，砂层具有较高的细度和高承压水头。在隧道施工过程中，水和土壤涌入冻洞的事件导致大量沉降，并破坏了隧道衬砌。然后采取了补救措施，以防止事故发生并加强受损的隧道衬砌。本文分析了水土涌入的原因，对隧道的破坏以及补救措施的效果。事故的主要原因是由于隧道外部的高水压，水和砂子穿过冻结管和井口孔管之间的间隙渗透。监测结果表明，注浆和衬砌钢筋环加固有效地提高了隧道结构的稳定性。该案例研究为将来的类似隧道项目提供了实践经验和指导，以减轻水土涌入的风险。