Designing a Retaining Wall
The first step is to determine whether you need a gravity wall or reinforced wall.
Gravity Walls
Gravity walls rely on their own weight and setback to hold up the soil behind them.
Reinforced Wall
Reinforced walls use layers of geogrids to combine the soil and block together to form a reinforced soil mass.
Maximum Wall Heights - AB Gravity Walls |
|||||||
|---|---|---|---|---|---|---|---|
| Condition above retaining wall |
Soil Type | AB Stones only of AB Collection 12° (Ref) |
AB, AB Metropolitan, AB Aztec & AB Europa Collections 6° (Ref) |
AB Fieldstone Short Anchoring Unit (SAU) 6° (Ref) |
AB Fieldstone Long Anchoring Unit (LAU) 6° (Ref) |
||
Level
|
Clay | 3 ft. 6 in. 1.0 m |
3 ft. 2 in. 0.9 m |
3 ft. 7 in. 1.1 m |
5 ft. 10 in. 1.8 m |
||
| Silty Sand | 5 ft. 4 in.** 1.6 m |
4 ft. 7 in. 1.4 m |
5.0 ft. 1.5 m |
8 ft. 6 in. 2.6 m |
|||
|
Surcharge* 100 psf (4.7 kPa) 
|
Clay | 1 ft. 8 in. 0.5 m |
1 ft. 4 in. 0.4 m |
1 ft. 8 in. 0.5 m |
4 ft. 1.2 m |
||
| Silty Sand | 3 ft. 10 in. 1.1 m |
3 ft. 1 in. 0.9 m |
3 ft. 7 in. 1.1 m |
7.0 ft. 2.1 m |
|||
Slope 3:1
|
Clay | 2 ft. 8 in. 0.8 m |
2 ft. 4 in. 0.7 m |
2 ft. 8 in. 0.8 m |
4 ft. 4 in. 1.3 m |
||
| Silty Sand | 4 ft. 8 in. 1.4 m |
4 ft. 1 in. 1.2 m |
4 ft. 4 in. 1.3 m |
7 ft. 4 in. 2.3 m |
|||
Table 1 is based on Clay soil having an internal friction angle of 27° (Ref) or better and a Sandy soil having an internal friction angle of 32° (Ref) or better. All heights based on exposed wall heights and include a cap block. The gravity wall heights shown above do not account for seismic loading. Check with a local engineer for assistance if you are in a seismic area. Final designs for construction purposes must be performed by a local registered Professional Engineer, using the actual conditions of the proposed site. *The Surcharge loading category above assumes a solid surface such as concrete, asphalt or pavers having a suitable supporting subgrade.
**Chart Example: A 5 ft. (1.5 m) tall wall in sandy soil with a level surface above can be built with AB Stones of the AB Collection and would typically not require reinforcement, but will require review by a local professional engineer.