Declared of public utility on the 31st January 2013, the extension project of the RER E line towards the occident (Eole) aims to improve the transportation and to strengthen the connections between the east and west of Ile –de –France, proposing a new quality of service. The current line E of the RER will extend for 55km towards west, of which 8km of tunnel, from the station Haussmann Saint-Lazare to the station Mantes-la-Jolie. 47km of existing tracks will be modified in order to create three new stations: Porte Maillot, La Défense-CNIT and Nanterre-la-Folie. The commissioning of this line will be gradual. In the year 2022, the RER E will serve the west part in Nanterre, to continue in the year 2024 with the east-west link, which will take you as far as Mantes-la-Jolie, in order to reach la Défense in 40 minutes compared to 52 minutes today. 

There are more of 620 000 passengers who use this service. This project foresees the construction of an underground station of 18.000 m^2, the creation of fast and fluid interconnections in France’s busiest multimodal station (connection to other major lines) and direct access to the La Défense forecourt. This project will also include the CNIT, with the creation of 7000 m^2 of new commercial activities. End of 2015 the first works of the station started with the diversion of networks in the CNIT; a multi-level opening under the CNIT to ensure the logistics of the site and then to continue later on with the installation of escalators/stairs/lifts to connect the station to the CNIT. The works will then include the resumption of the car park bases under the CNIT with the creation of a slab under which the station will be excavated. In the last phase of the project the realization of the structures will be realized followed by the excavation, with day and night works in the year 2018. The development of the construction site is in progress. The principal phases of the project envisage the creation of an acoustic sarcophagus so as not to interrupt the activities of offices and companies (which accommodate more than 25 000 people a day) at CNIT. Realization of an access at the site of the first parking level. Resumption of the subsoil of 118 pillars that support 75 000 tons of load on the existing structure; in particular, the creation of new foundations to temporarily replace the existing ones. Each pillar is surrounded by a metal and concrete support structure consisting of 12 to 16 posts. Demolition of the surface foundation beams under each post. Pre-excavation. Construction of shafts/columns (60). Realization of the load transfer plate. Excavation of the station volume. In the context of the construction of the station for RER E located under the CNIT, the company CIPA SARL worked on the construction of 28 armored shafts. It is a matter of excavating and supporting the well by means of digging steps until the bottom of the excavation is reached. The armored shafts are temporary works that make it possible to build the columns of the supporting structure of the new station. In particular, have been given to CIPA shafts of circular oval and rectangular shape with variable sections starting from 12,5 square meters to 34 square meters, and a height between 13,5m and 18,5m. The shafts have a longitudinal “elephant’s paw” profile, i.e. in the final part of the well (about the last 4-5m) the section increases linearly with the depth while maintaining the same shape as the section in most cases, and in the remaining part also by changing the shape of the section, in function of the formworks which will be positioned in the realization phase of the piles, the last sections at the bottom of the well were 42 square meters in size. Particular attention has been paid to the quality of the support, where during the casting we proceeded with the levelling of the Spritz concrete for the whole well covering, and also in the lower part (depending on the technical drawings of the individual wells), where waterproofing panels were to be applied, the spritz concrete layer was smoothed with plaster to ensure perfect adherence between the wall and the panel. The worksite in question can be found under the 5th level of the underground parking of the CNIT. The wells have been realized starting from a platform above the well. The excavation has been made thanks to electric demolition machines such as Brokk 160,170 or 200.

In the contest of the Eole project, in the area of the Puits Traingle worksite, Cipa worked in the excavation and to the support of four galleries of irregular geometry and with a variable section of 9,8 and 12,3 square meters with a length of 60m. These galleries after being realized and then completely reinforced and filled with concrete, form a structural canopy support of the pilot gallery.
Working in very confined and reduced spaces, with the goal to limit at the maximum the pollution made by the emission in order to limit as much as possible the pollution caused by the emissions of the means of work, for what it concerns the excavation phases, have been privileged the Brook electric vehicles. The works have been executed by Cipa in the following phases: excavation and subsequent finishing work ,prefinishing  of Spritz Beton fiberglass, positioning of the cross-linked core, filling of spritz beton. In particular in one of the galleries, for 8 consecutive meters, have been necessary also threading rods, subsequently sealed with resin, were also required for the consolidation phase.

Job worksheet
Place: France - Paris
Period: November 2018 - March 2021
Client: Vinci Construction
Value: 1.736.000 EUR
Status advancement work: 100%

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