- Client: AUTOROUTES DU SUD DE FRANCE
- General Contractor: INGEROP CONSEIL ET INGENIERIE
- Assignment: Geotechnical project management
- Total cost of work: AVP / PRO: €552k; VISA / DET: €434k
- Completion date: 2006-2016
PROJECT DESCRIPTION AND CHARACTERISTICS
The study carried out by GEOS Ingénieurs Conseils enters into the project of moving the A9 highway to Montpellier.
This 23-kilometer-long route consists half in widening the existing highway and half in building the new line.
In terms of earthworks, the route is deficient: 3.1Mm³ of embankments for 1.2Mm³ of cuttings excavated soil.
The new route crosses, in its central part, a vast plain of alluvial spreads (Lez-Lironde, Lantissargues…) and goes along the TGV line CNM under construction in a sector of compressible land, with a great lateral variability.
The backfills, 6- to 12-meter-high, were set up in advance to minimize their interaction with the CNM project. Vertical drains have been implemented under the most sensitive technical backfills.
ASSIGNMENT
GEOS, in collaboration with INGEROP’s engineering teams, the project’s Prime Contractor, carried out the geotechnical design studies (dossier: Highway Pre-project Phase) and carried out the geotechnical monitoring of the works (VISA, DET) .
This is defined in the NFP 94-500 standard for the G1-PGC / G2-AVP / G2-PRO / G2-DCE / ACT and G4 missions. These studies particularly addressed the following points:
- Definition of the geological, geotechnical and hydrogeological context of the project,
- Drafting of geotechnical parts of APA TCFH,
- AVP and PRO: Studies of earthworks (stability, slopes, settlements) and engineering structures,
- Definition of the complementary measurements (mask in cuttings, vertical drainage and preloading of the technical blocks),
- Definition of auscultations to be implemented,
- ACT: Technical assistance to write the tendering package and to examine the tenders,
- Approval of geotechnical implementation studies, approval forms and execution procedures,
- DET: Geotechnical supervision of the engineering structures.
