中文摘要：

城市地铁的快速发展难以避免频受外部工程活动扰动影响,其中突发堆载已成为突出问题。上海某地铁区间盾构隧道上方突发大量堆土,最大堆高约7 m,从而引发结构产生横向收敛大变形（ΔD）最大达到34.5‰倍的隧道外径（D）,堆载严重威胁到地铁结构及运营安全。介绍了该工程案例,包括堆载引起的隧道结构横纵断面变形及相应的结构病害,提出并实施了及时卸载、堵漏及碎裂修补、后采用芳纶布及钢环结构补强的结构整治措施。卸载对于减缓堆载对隧道结构沉降影响作用明显,卸载之后隧道沉降恢复且部分产生隆起现象,后续张贴芳纶布及钢板环加固措施,可提高盾构隧道横断面承载能力,相比隧道沉降,隧道结构收敛变形状况改善并不明显,水平直径收敛最大仅回缩2.6‰D。案例对于外部扰动对盾构隧道影响及整治研究,具有重要的工程实践价值。

英文摘要：

As the metro system is being developed rapidly these years in China, the metro tunnels are frequently influenced by nearby construction activities, of which the extreme surface surcharge probably is the most serious one. It will seriously threaten the safety of the lining structure and its serviceability. A field case of metro tunnel with an unexpected surcharge 7 m in height in Shanghai is introduced in details at first. The inspected defects and monitored deformation of the tunnel caused by such an accidental surcharge are introduced. The largest convergence has reached 34.5‰ times the tunnel outer diameter D. The improvement measures, including the unloading, FRP reinforcement and steel plate reinforcement, for the lining structures are then proposed. Based on the monitoring and inspection data, the effect of improvements on the deformation is finally discussed. The unloading has significantly reduced the longitudinal settlement of lining and even made the ring heave in some typical rings. But it has little effect on the tunnel transverse convergence. The reinforcement by using FRP and steel plate has enhanced the bearing capacity for the tunnel lining ring. It should be helpful from this detailed case to study the influence of the repair work on the metro tunnels under the extreme surface surcharge.