ABSTRACT
Shield tunnels are very sensitive to the ground motion. The protection of operating shield tunnels is important during the construction of underground space. This paper introduces three typical soil arching, termed as “upward”, “downward” and “lateral” soil arching in light of their developing direction with respect to the ground gravity during the underground construction. Theoretical models are proposed to describe the ground stress and deformation transfer associated with the developing soil arching. The impacts of the nearby construction on the existing shield tunnels are evaluated considering the soil arching. It is found that a significant increase in structural deformation occurs when the loosened zone of soil arching develops to the existing tunnel. Countermeasures regarding protection of the nearby tunnels are developed by mitigating the expansion of the loosened zone and reinforcing the loosened zone. Finally, engineering applications of the countermeasures are also introduced.
