Components, systems and materials › Slope protection and rockfall › Geogrid
Geogrid
What it is
A geogrid is a polymer grid with open apertures that lock into soil or aggregate, used to reinforce soil.
Where it is used
Reinforced soil walls and steep slopes, embankments on soft ground, base reinforcement under roads and railway ballast.
How it works
Aggregate particles poke through the apertures and are held by the ribs. When soil tries to move, the grid takes tension and spreads it over a large area. Layers of grid turn loose fill into a coherent reinforced block.
Types
- Uniaxial geogrids (strength mainly in one direction, for walls and slopes)
- biaxial geogrids (for bases)
- triaxial geogrids
- welded, extruded and woven-coated types
Materials
High-density polyethylene, polypropylene or polyester.
Reinforced soil design checks external stability of the block and internal pull-out and rupture of each layer, using long-term design strength that allows for creep, installation damage and durability. BS 8006-1 is a common reference.
Installation and QA steps
- Prepare foundation
- Lay grid in the correct direction
- Tension slightly and pin
- Place and compact fill in layers to the design thickness
- Connect to facing units where used
- Grid laid in the wrong direction
- Fill compacted with heavy rollers too close to the facing
- Fine-grained fill that does not interlock
Codes cited
- BS 8006-1 (UK): Code of practice for strengthened/reinforced soils and other fills.
- IRC:SP:59 (India): Guidelines for use of geosynthetics in road pavements and associated works.
Cited by number only. We do not reproduce code text, tables or figures.
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