By Ashley Karen
Images released by Société du Grand Paris reveal the work being delivered by the Horizon consortium on the Vert de Maisons station, a critical interchange on the new Line 15 south of the Grand Paris Express project.
Horizon consortium comprises Soletanche Bachy France, Bessac, Soletanche Bachy Tunnel and Bouygues Construction. It is constructing four stations as well as 4.2km of tunnels for the new line, which is part of the general £28bn Grand Paris Express project to provide 200km of new metro lines and 68 new stations in the suburbs of Paris.
With platforms at 35m under the ground, Vert de Maisons station is one of the most in-depth on the Grand Paris Express project.
The new station at Vert de Maisons will deliver a fundamental connection between Line 15 South and the current RER D line and passes close to the Paris-Lyon-Marseille high-speed line. In addition to the problems of linking with the RER station and without disrupting high-speed trains, the new station box is being constructed beneath a group of listed structures dating from the 1930s.
Horizon has used ground freezing techniques and grout stabilization to allow the 74m deep diaphragm walls for the station box to be constructed and bored without affecting the buildings overhead.
The latest views of the site from the photographs taken by Société du Grand Paris indicate that platform tunnel boring is advancing satisfactorily as above-ground construction for the station construction takes shape.
The platform tunnels are being developed by mechanical excavation on either side of the TBM-driven tunnel, and work is now underway to clear the soil that separates these “galleries” from the main tunnel.
Pierre Bannier, Horizon Vert de Maisons station project manager, pointed out: “As the digging of the cavern takes place under an inhabited district, we deployed innovative techniques, such as freezing the soil, to ensure the stability and impermeability of the terrain.”
He continued: “The hollow cavity was also reinforced by installing metal reinforcement, preventing any risk of subsidence.”
As Société du Grand Paris claimed, it has taken Horizon two and half years to reach this stage of construction and work is anticipated to be finished by the end of the year. So far, Horizon has bored 17,400m3 of material for the platform caverns, which are 35m under the ground level.
