Evolution of tunnel uplift and deformation induced by an upper and collinear excavation: A case study from Shenzhen metro

Abstract

This paper presented a case study in Shenzhen metro where the evolution of the tunnel uplift and deformation was investigated based on the field observation. The deformation of tunnel, diagram wall and ground surface were carefully measured over 400 days. The tunnels had been significantly uplifted by 34 mm, while less convergence deformation was observed in each section. For the long excavation collinear to the underlying tunnel in Shenzhen granite residual soil, the superposition unloading of the other adjacent upper and collinear excavation activities has a more significant impact on the tunnel uplift compared to the excavation of upper section, which lead to more than half of the tunnel uplift amount. In addition, a slight twist deformation was observed in the tunnel section, which need to be focused in the evaluation of tunnel safety because it is a main contribution to the tunnel diseases. The well-document site data and results can provide systematic field data and useful engineering reference for similar projects.