SYSTRA SWS is responsible for the design of tunnel and cross passages connections, including temporary and final supports, for section 2 of Line 15 South. The tunnel boring machine (TBM), launched in 2018, is the first machine to have completed its course out of 21 TBMs to simultaneously dig the 105 miles of tunnels necessary for the project. This includes the construction of four stations, several related structures, 4.5 miles of tunnels, and the launch shaft for the TBM.
The soil is varied and complex, thus calling for very special techniques to reinforce it. The Vert de Maisons Station is built with 240-feet-deep diaphragm walls and using conventional methods for the foundation excavation, the Vert de Maisons Station requires ground freezing and injection techniques to stabilize the soil. Moreover, the tunneling proceeded under the Parisian suburbs.