NAUE geogrid-reinforced steep slopes give the Feyzin Fortress a completely new appearance

Location of work/project:



France, Feyzin/ Geogrid-reinforced steep slopes


Geogrid-reinforced earth structures offer designers a number of options and thus provide a high degree of flexibility and freedom in the design of surface facings. At the Fortress of Feyzin in the Rhône-Alpes region, this allowed a disused military base to be converted into an attractive recreation area.

The new facility planning had to carefully account for the existing building. Also challenging, the redevelopment needed to be visually appealing as soon as possible. The designers opted for reinforced steep slopes, which utilized the NAUE m³ Steel P system. The system offered numerous advantages:
• Permanent stability even on slopes to 90°
• Ecological benefits associated with the use of local soils include decreased transportation pollution (and cost) and conservation of natural resources
• Extremely economical, due to the ability to utilize more affordable cohesive soils rather than dispose of or replace them with non-cohesive soils
• Quick and easy construction

The design of the geogrid-reinforced retaining structure was carried out by BBG Bauberatung Geokunststoffe GmbH & Co. KG in Espelkamp, Germany.

The slope has an inclination of 68° and a height of up to about 9.5m. NAUE Secugrid®80/20 R6 geogrid was placed in layers, each of which was covered with a 70cm thick layer of compacted fill and then folded upwards. Locally available soil was used as the fill. Ensuring that the steep slope blended smoothly with the existing historical structures, such as walls, gates and balustrades, proved challenging. Here, the NAUE m³ Steel P System demonstrated its strengths. The Secugrid® geogrid, which is made of drawn, monolithic flat bars with welded junctions, is robust, and easy to handle and place on site. It is more an economical than traditional construction method when steep slopes have to be reinforced. Galvanized steel-mesh elements form the facing of the geogrid reinforced soil structure. A nonwoven geotextile placed inside the mesh prevents fines from being washed out. The steel-mesh elements were pre-bent to an angle of 90° and each layer was placed a short distance back from the one below. This resulted in small berms on which vegetation was established. More than 5.000m² of Secugrid80/20 R6 were installed.