- Design-construction: VINCI Group
- Assignment: G2-PRO & G3
- Total cost of the work: 90 k€
- Completion date: 2014-2015
PROJECT DESCRIPTION AND CHARACTERISTICS
The study conducted by GEOS was part of the construction of the second bridge over the Wouri River in Douala (Cameroon). It concerned the access to a structure which represents a linear of 700 m long on the right bank (Bonabéri) and 2,000 m long on the left bank (Deïdo). It supports a road as well as a railway. The longitudinal accesses profile is mainly filled and its height can reach 9 m. Accesses also include the construction of three engineering structures and twelve hydraulic structures.
The geological context is characterised by the Wouri alluvium: the alternation of fine soils (clay, silt) and sandy soils of significant thicknesses (greater than 30 m) with very compressible layers (soft clay, mud …).
The encountered difficulties and, in particular the settlements (consolidation, creep) required the use of soil reinforcement (completion of rigid inclusions) for the abutment on the left bank. In addition, a test embankment is under construction. GEOS will exploit the results for the rest of the project.
ASSIGNMENT
GEOS conducted the studies from project to execution level (G2 and G3 missions according to the NF P 94-500 standard) for access to the second bridge over the Wouri.
This study particularly approached the following points:
- Geotechnical hypothesis notes for earthworks, engineering structures and access hydraulic structures,
- Geotechnical studies of the project and execution of access earthworks and technical blocks of the bridge.
