Evaluation of the Ground Settlement in an Urban Area Resulting from a Small Curvature Tunneling Construction

The transportation system is one of the major infrastructures in urban areas, and it serves 56% of the world's population. Nowadays, metro lines are developing fast in urban areas. Due to the restrictions of urban fields, metro lines are usually not planned straight, and a curved line is required to connect stations in different locations in a city. As a result, small curvature tunnels are commonly constructed in urban areas. The tunneling construction in a city area may cause ground settlement, which is sensitive to surrounding buildings and underground utilities. The aim of this study is to explore the impact of curvature alignment on the ground settlement. In this paper, ground settlements induced by small curvature shield tunneling were evaluated by using a numerical analysis. A total of six cases were selected for the analysis. The results obtained from the numerical simulations were compared with Peck's equation. It is observed that Peck's equation can be used for the estimation of the maximum settlement. However, the ground settlements on both sides of the central axis of the curved tunnel are asymmetrical, and Peck's equation, which provides a symmetrical settlement, may not be applicable in the case of small curvature tunnels.