Components, systems and materials › Slope protection and rockfall › Gabion
Gabion
What it is
A gabion is a wire-mesh box filled with stones. Stacked and tied together, gabions make retaining walls, river-bank protection and check dams that are heavy, flexible and free-draining.
Where it is used
Hill roads, river training, culvert outfalls, bridge approach protection, landslide toe walls and landscape walls.
How it works
A gabion wall is a gravity structure: its weight resists the earth or water pushing on it. Because the boxes are flexible they tolerate settlement without cracking, and because they are porous no water pressure builds up behind them. Vegetation and silt gradually fill the voids and the wall becomes greener and more stable with age.
Types
- Box gabions
- sack gabions
- welded-mesh gabions
- double-twisted hexagonal-mesh gabions
- gabion walls with stepped faces
Materials
Zinc or zinc-aluminium coated steel wire, often with an extra polymer coating in aggressive water; hard, durable, non-weathering stone larger than the mesh opening; lacing wire or rings.
A gabion wall is checked like any gravity wall for sliding, overturning, bearing pressure and overall stability, with a batter or steps toward the retained side. A geotextile filter behind the wall stops fines washing through. ASTM A975 covers double-twisted mesh gabions and mattresses.
Installation and QA steps
- Prepare a level foundation and lay geotextile where needed
- Unfold baskets, assemble diaphragms and lace edges
- Place and tie empty baskets to neighbours
- Fill with stone in layers by hand or careful machine placing, fitting internal bracing wires
- Overfill slightly, close lids and lace
- Backfill behind in compacted layers
- Undersized or soft stone escaping through the mesh
- Coating abraded by boulders in rivers
- Poor lacing letting boxes bulge
- Scour undermining the toe
Codes cited
- ASTM A975 (USA): Double-twisted hexagonal mesh gabions and revet mattresses.
Cited by number only. We do not reproduce code text, tables or figures.
Related
- Geotechnical and Foundation Engineering
- Irrigation and Water Resources Engineering
- Highway Engineering
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