A high-performance lightweight embankment to secure riverbanks exposed to erosion and hydraulic fluctuations
As part of the redevelopment of the Maine riverbanks, 800 m³ of Nidaplast RA honeycomb blocks were installed to create a lightweight, draining embankment along the riverside roads in the heart of Angers.
This solution reduces pressure on the retaining structure, resists flooding, and improves bank stability in an area subject to strong hydraulic dynamics.
800 m3
lightweight fill
6
honeycomb blocks
2017
year of completion
Project Context and Challenges
Combating erosion and securing a riverbank in a wetland zone
The riverbanks of the Maine, heavily affected by water-level variations and natural erosion, required intervention to:
- reinforce an existing retaining wall,
- limit landslide risks,
- reduce pressure on tie rods supporting the sheet piles,
- ensure stable behaviour of the structure even during floods.
The project involved erecting a retaining system and filling the space with a lightweight embankment while ensuring controlled water management.
Objectives Defined by the Project Owner
The specifications required:
- reduction of vertical loads applied to the sheet-pile tie rods,
- hydraulic transparency between the bank and the groundwater,
- resistance to significant hydraulic stresses,
- prevention of overpressure and soil movement,
- rapid and durable installation.
Solution Implemented with Nidaplast
Nidaplast RA lightweight fill: stability, drainage, and hydraulic resistance
The embankment consisted of 6 layers of Nidaplast RA honeycomb blocks, installed between the retaining wall and the geotextile ensuring the filtration of fine particles.
RA blocks, composed of 95% void, allow groundwater to naturally fluctuate within the structure without creating overpressure on the riverbank.
They are an advantageous alternative to traditional heavy fill materials, which would increase stress on the existing structure.
Key advantages in this context:
- Major structural lightening: reduced vertical loads
- Natural drainage through the honeycomb structure
- High mechanical resistance under permanent loads
- Suitable for flood-prone banks and sensitive hydraulic environments
- Durable, long-term stability without settlement
- Easy installation thanks to lightweight, hand-portable blocks
Technical Characteristics of the Installed Product
Block dimensions:
2400 x 1200 mm.
Honeycomb block height:
520 mm.
Permeability:
≥ 95 %.
Material:
100% recyclable polypropylene
Nidaplast RA
Nidaplast RA lightweight embankments are extremely light and resistant. These honeycomb structures are the recommended solution for constructing landscape embankments, road embankments, or building embankments.
View product sheetInstallation Process
1. Preparation
Installation of the retaining wall (sheet piles + tie rods).
2. Laying the Nidaplast RA blocks
Successive installation of the 6 staggered layers of Nidaplast RA
3. Backfilling
Final backfilling, compaction in successive layers, and upper-level finishing.
Results and Benefits Observed
Riverbanks stabilised and secured against erosion and flooding
Significant reduction of load on sheet piles
Effective prevention of hydraulic overpressure thanks to the honeycomb structure
