Grouting-induced ground heave and building damage in tunnel construction: A case study of Shenzhen metro

This paper presents a case study of the grouting-induced ground heave and building damage in the tunnel construction of Shenzhen Metro Line 10, which passes through a crowded urban area with water-rich strata in Shenzhen, the province of Guangdong, China. It was reported that the ground surface heave of up to approximately 500 mm was observed, and the customs building above the tunnels was seriously damaged because of a 200 mm heave. Such a significant heave was closely associated with the advanced curtain grouting adopted in the tunnel construction. To this end, the heave of the ground surface and the displacement and deformation of the customs building were examined. The discrete element method (DEM) was then used to qualitatively analyze the relations between the grouting parameters and the ground disturbance. The results demonstrated that the poor dewatering work in the early stages increased the difficulty of grouting. The grouting materials with high viscosity and large grouting pressure were required for water blocking because of the large amount of confined water in the tunnel, resulting in fracture grouting. The ground was then uplifted due to the large inflow of the slurry and the excess pore water pressure. Finally, the lessons learned from this incident were discussed. The presented case study provides a reference for tunnel construction in urban areas with water-rich strata.