Settlement management for urban tunnels: an example from France

Abstract

The TOULON highway tunnel is located in a very dense urban environment, and a much complex geology. The excavated section is about 120 m2 and the depth is in the range 15-35 m. The aim of the paper is to show how a great attention was paid to the settlements control: at the design stage through soils investigations, survey of existing constructions in regards to their sensibility to tunnel induced settlement, definition of settlements thresholds, and choice of ground pre-reinforcement techniques; during the construction, by heavy monitoring of deformations and continuous adaptation of the supports to the actual settlements and buildings behavior. This case history is an illustration of how the settlements induced by tunneling can be managed for any urban tunnel, mainly in old cities.