{"id":14904,"date":"2020-10-23T14:16:57","date_gmt":"2020-10-23T12:16:57","guid":{"rendered":"https:\/\/www.soletanche-bachy.com\/?p=14904"},"modified":"2023-03-08T14:32:37","modified_gmt":"2023-03-08T13:32:37","slug":"a-look-back-at-the-complex-cnit-project-in-la-defense-france","status":"publish","type":"post","link":"https:\/\/www.soletanche-bachy.com\/en\/a-look-back-at-the-complex-cnit-project-in-la-defense-france\/","title":{"rendered":"A look back at the complex CNIT project in La D\u00e9fense \u2013 France"},"content":{"rendered":"
23\/10\/2020<\/p>\n<\/div>
In 2016, as part of a consortium, Soletanche Bachy acquired works packages GC-DEF1 and GC-DEF2 for the RER E underground line (EOLE project). The work, which began in the summer of 2016, is part of the extension to RER line E between Haussmann-Saint-Lazare and Nanterre-La Folie.<\/strong><\/p>\n<\/div> It involves building a section of the RER E underground line (EOLE project, particularly including a 220m long underground station beneath the CNIT in La D\u00e9fense.<\/p>\n The project is complex and very constricted given the highly urban environment of La D\u00e9fense, with the vast majority of the work taking place underground:<\/p>\n Works package GC DEF 1 was broken down into three main parts:<\/p>\n The Gambetta West construction shaft, 15m in diameter and 40m deep Two single-track tunnels of 150m and 155m from La D\u00e9fense station to the western tunnel connecting structure The station beneath the CNIT is being constructed below the CNIT\u2019s lowest existing parking level. To complete the earthworks, 2,000 micropiles need to be installed, provisionally by reinforcing the foundations of the CNIT car park, while the posts for the future station are constructed. The earthworks can then continue, sheltered by nailed wall or micro-Berlin-type walls, anchored as the earthworks progress (more than 8000m of drilling!). Widespread pumping makes it possible to work out of the water table.<\/p>\n Construction of the various tunnel openings between the surface and the CNIT station also requires retaining works such as micro-Berlin-type wall and pipe roofing, thereby increasing the number of work areas. Compensation grouting<\/a> through the tunnel beneath the Exaltis building is also planned.<\/p>\n Certain retaining works to be carried out along existing railway lines must be carried out within very tight deadlines, with a complete suspension of traffic and organisation in three shifts, 24 hours a day, seven days a week.<\/p>\n The tunnelling work began at the end of 2017 from two points (the Gambetta shaft and Triangle shaft), to connect to the CNIT.<\/p>\n \u2026..<\/p>\n\n
1. Adjacent tunnels and structures to the east of La D\u00e9fense station<\/h3>\n
\nIntersection vault between the Gambetta West and Gambetta East shafts (not included in the contract), 25m long
\nA two-track 95m tunnel with a 9.5m opening
\nA 76.5m tunnel connecting structure divided into two 10.5m chambers
\nTwo single-track tunnels of 250m and 270m leading to La D\u00e9fense station<\/p>\n2. La D\u00e9fense station with its connections and tunnel openings<\/h3>\n
3. Adjacent tunnels to the west of La D\u00e9fense station<\/h3>\n
\nThe tunnel is excavated using a traditional method, passing under high-rise buildings, requiring preliminary reinforcement and underpinning by using micropiles<\/a>, as well as compensation grouting.<\/p>\n