Koumba TBM reaches daylight in Paris!
The excavation of the main tunnel of Line 14 beneath Orly has been completed after a 4 km run under the Airport areas. The 8.8 m-diameter EBP machine “Koumba” is the first on the Line 14 South to cross the finish line, standing out for its remarkable advancement rates, with a record of 35 m in 1 day.
The tunnel is set, from the geological point of view, in swelling clays and soft marlstones, with a layer of weathered travertine on the top. The geotechnical instrumentation has allowed to validate the undrained behaviour of the fine-grained soils and the influence of the excavation on the pore water pressure.
The correct application of the confinement pressure has successfully limited the induced effects of the settlement on the existing structures, such as airport taxiways and terminals, viaducts, and deep pipelines.
Following the detail design phase, SWS, in partnership with EGIS, was in charge of the TBM follow-up and back-analysis of the excavation parameters during construction. We are very satisfied with the result achieved and we thank the construction companies NGE-WeBuild and all the actors involved for this great experience.