What are Gabion Walls? – Application, Advantages & Disadvantages

A gabion wall is a wall built from wire-mesh cages filled with stone. Gabion walls are rarely built with a sheer vertical face: they are usually battered (angled back towards the slope) or stepped back course by course into the retained soil.

They can be used to control flood water flow around a vulnerable structure.

A gabion stepped weir is common in river training and flood control: each step makes the water drop and lose energy, so the flow leaving the weir is slower and less erosive.

Gabion Wall Types

Gabion units are chosen by cost and function. These are the most common types:

1. Gabion Basket

A rectangular wire-mesh box, supplied in a range of standard sizes and used in highway and railway construction for retaining walls, abutments and embankment protection.
It is most cost-effective where suitable fill stone is available or a quarry is close to the site.

2. Gabion Mattress

Also called Reno mattresses, these are much shallower than gabion boxes and are laid flat or on gentle slopes.
They line channels and protect beds and banks from erosion, so they are designed for the flow velocity and wave action at the site.
A typical size is 6 metres long, 2 metres wide and 0.3 metres thick.

3. Gabion Sacks

Cylindrical mesh sacks that are porous and flexible and can be filled and placed quickly, even underwater.
They are used in emergency hydraulic works, such as closing breaches and protecting eroding banks during floods.

4. Gabion Wire Mesh

Double-twisted hexagonal mesh is also used on its own, draped over rock slopes along roads and railways to hold back falling rock and stones (see rockfall protection).
On soil slopes next to highways and railways it holds the surface against erosion.
Combined with geogrid reinforcement in the fill, it is used to build reinforced embankments and steep slopes.

Advantages of Gabion Walls

1. Construction and Handling

Gabion components are easy to transport to site, unload and install. The stone fill can be chosen in different sizes and colours to suit the volume and look of each wall. Gabions can follow a grade along a wall, build up stream banks and strengthen coastal dunes, and the top of a gabion wall can step down to follow changes in ground level.

There is no curing time, so construction moves quickly.

2. Endurance

The wire mesh flexes, so gabion walls deform instead of cracking or separating. They take repeated pounding from waves and stream flow without breaking apart. Hard, durable stone fill resists years of water erosion, and galvanised (or PVC-coated) wire resists corrosion and rust.

3. Application

Gabions can form pond and dam walls, and can be used as cladding on structures. A concrete capping can be cast on top of a gabion wall, as on a masonry wall. Gabions protect stream beds, riverbanks and drainage channels and help stabilise slopes. They guard against mudslides and slope failures where the topsoil is loose and has no root cover. On beaches and tidal berms, gabion barriers resist storm surge and wave erosion.

4. Drainage

The voids between the stones keep a gabion wall permeable, so runoff drains through naturally and water pressure does not build up behind it. On the water side, the rough stone face breaks up the flow and slows it down.

Disadvantages of Gabion Walls

1. Aesthetics

In river, pond and beach settings, gabions can look artificial. The straight, regular faces look mechanical next to natural rock. On tourist beaches, where long and heavy barriers are needed to protect large stretches of shore, large gabion walls can spoil the view.

2. Maintenance

If the stones shift or wear down inside the baskets under heavy water and wave action, the affected units have to be opened and refilled, and sometimes dismantled to reach the damage. Damage to the bottom courses of a tall gabion wall means removing the courses above, which is costly and slow.

3. Wall Assembly and Cost

Gabion walls are an economical choice for most uses, but they cost more to build than a natural vegetated slope or riprap. Large units have to be lifted into place, so heavy machinery is needed.

4. Abrasion in Fast Water

In high-velocity streams and under wave attack carrying sand and gravel, the wire mesh can abrade and tear open, spilling the stone fill.

5. Inspection

Gabion structures need regular inspection, and should be checked again right after any storm that brings higher-than-normal water flow.

Gabion Wall Applications

Gabions are used for retaining structures such as retaining walls, revetments and toe walls, including at dams.
They protect sea walls, riverbanks, canal banks, dams, weirs, reservoirs and lake shores against erosion.

1) Cylindrical (sack) gabions are used in foundations and small dams.
2) Gabion walls are used as noise barriers.
3) A gabion wall can serve as a temporary flood wall.
4) They can redirect flood water away from a vulnerable structure.
5) Stepped gabions dissipate energy in channels.
6) They are also used for decorative walls in landscaping.
7) They are used as a retaining wall at the toe of a steep slope.
8) They slow down weathering and erosion of exposed slopes and banks.

FAQs

If you are weighing a gabion wall against a reinforced soil wall, our guide on when to use geogrid in a retaining wall explains the conditions that call for geogrid and compares the main wall options.

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