ABSTRACT
The extension of line 11 of the Paris metro required an adaptation of the current terminus of the line, the Mairie de Lilas station. Three new accesses are therefore to be built by means of conventional tunneling methods. Conventional excavation methods are adopted. All the challenges involved by underground excavation in urban environment must be dealt with, such as the interaction with the existing structures, the sensitivity of the adjacent buildings, the uncertainties related to underground infrastructures and to the soil characteristics. A robust traditional calculation approach is used, supported by finite element analyses and the BIM method. The observational method was implemented, coupled with alternative solutions designed beforehand. The continuous coordination between the construction site and the consultant allowed to face the risks and to quickly adjust the design solutions to the unexpected situations.
