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Following the landslide of a slope along the river Seine, close to a housing estate, a preliminary diagnostic highlighted that a stabilising solution was necessary to to secure the housing estate. In this urban context with high space constraints, various technical solutions were considered in oeder to find the best fit between the works and the site conditions, i.e. its geology, but also space constraints.
The landslide is located in green sand and Argenteuil and Pantin marls layers. An older slide due to the operation of a quarry certainly participated in triggering the landslide, as did the heavy rainfalls in 2000 and 2001.
Indeed, an old trench, filled with draining materials, was located near the old slip plane. It may have contributed to rehydrate the clays by stagnating rain, making it more plastic, hence reactivating the slide.
The selected technical solution consisted in:
- Stabilising the landslide scar with a soil-nailed wall 130m long and 6m high.
- Draining the massif with deep draining trenches downstream the landslide and subhorizontal drains in the soil-nailed wall,
- Reprofiling the downstream embankment at 4H/1V
Terrasol’s achievements:
TERRASOL produced the slope stability calculations, designed the repair project, prepared the tender documents and was entrusted with the project management of works. Topographic monitoring of the slide evolution was performed in the frame of an interactive design approach during the period of dialogue with the estate residents (2 years).
