Geotechnical assistant to the client for the construction of the South-East section of the line 15

Project description

The south-east section of line 15 (section T2 of the red line) of the Grand Paris Public Transport Network is located between the stations of Noisy-Champs and Villejuif Louis Aragon. This 26km section includes, for example, eight stations, a range of ancillary works (including ventilation shafts) and two maintenance yards at Champigny and Vitry sur Seine.

The notable geotechnical challenges encountered included:

•   Ground with poor geotechnical characteristics
•   Alteration of geotechnical layers below a quaternary covering
•   Swelling soils
•   High permeability
•   Decompressed or empty areas related to gypsum dissolution
•   Karst phenomena
•   The presence of underground quarries and backfilled sand extraction pits
•   Groundwater under pressure

Services provided

Assistant to the Client during the geotechnical surveying phase G2, including:

• Monitoring and control of the geotechnical surveys and tests being undertaken
• Updating the geotechnical model
• Preparation of the geotechnical summary report for the project, including the project parameters to be used
• The identification of the risks and the development of the general approach to geotechnical design for the project