By lyndamyer
Considering that the length of the Saint-Maur – Créteil station underground enclosure is not suitable to accommodate all of the platforms, in order to incorporating the future platforms for line 15 South, widening process of this tunnel constructed by the tunnel boring machine Camille was commenced in 2022.
The intended development plan was widening underground part of the station on 2 times 30 meters, along the tunnel. Also several security measures were taken ahead starting digging process of these two cavities which are called galleries. In order to reinforcing the ground in place, consisting mainly of chalk, forming a safety envelope around the tunnel, as well as controlling and preventing the risk of deformation during the digging of the galleries, Injections of grout (mixture of water, fine sand and cement) and filling the tunnel with a special concrete were the used methods respectively.
May 2022 was the date of beginning boring of the north gallery after these safety operations and it is due to be completed in March 2023 and in May for the south gallery.
“Using mechanized means (hydraulic breakers), a dozen workers take turns to dig on either side and then above the tunnel and create a vaultexplains,” said Antoine Delloue, works supervisor for the Eiffage – Razel-Bec consortium.
One meter increments over the entire height of the section concerned, is involving the digging process. Once completed, a waterproof coating is laid, before the complete concreting of the galleries. The determined time for advancing these operations is during extended hours, from Monday 6 a.m. to Friday midnight because of technical and security reasons, while they are likely to cause occasional nuisance. The site teams nevertheless take care to limit any inconvenience as much as possible. The great depth, 52 m underground, at which the work is carried out, also contributes to limiting the impact of the site on the life of the district.
Construction of huge barrettes (temporary foundations) to 83 meters deep in 2019 was due to supporting the intermediate levels of the station, whereas currently they replaced by permanent pillars and are sawn then evacuated from the construction site block by block. A few meters from the tunnel, the construction of the future platforms has already begun.
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