Abstract
To date, Shanghai has built an intensive network of metro tunnel system. In the operation of such a complex tunnel system, the vulnerability and the recovery of the segmental linings subjected to unexpected disruptions are badly concerned by the engineers and owners. In this respect, the analysis of segmental lining resilience, i.e., the ability to absorb the disruption caused by the hazards and then the ability to recover to the acceptable level of the functionality, is necessary for the safety of the tunnels. In Shanghai, from time to time, some dumped soils from construction site elsewhere are found to be disposed without permission at the ground surface above the operated tunnels. When the volume of these dumped soils are significantly large, e.g., a height of 5-8m, it will inevitably do threats to the safety of the underlying operated tunnels. In this paper, the resilience of the segmental lining system subjected to this unexpected extreme surcharge loads will be characterized with a real field case in Shanghai. The convergence deformation is regarded as the functionality of tunnels. The functionality curve is described using the measured data from a detailed monitoring program. The unloading of the dumped soils above the surface and the grouting around tunnel from surface are the two recovery measures both implemented in this field case. The calculated metric of resilience indicates that the functionality of the tunnels can be bounced back significantly using these two recovery measures. Besides, the rapidity of the recovery of these two measures is compared. Finally, some discussion and concluding remarks on the resilience of operated tunnels subjected to this extreme surcharge load are presented.
