CSLB C-27 Landscaping ContractorHardscape and FeaturesMedium
A landscape contractor is constructing a segmented retaining wall (SRW) that will be 6 feet tall. The soil conditions are average, and the wall will not have significant surcharges. What is a critical design consideration related to wall stability that must be accounted for in this scenario?
- AThe wall units must be mortared together for structural integrity.
- BThe top course of the wall must be capped with a poured concrete bond beam.
- CThe wall must be designed with a minimum 12-inch wide footing.
- DThe wall requires geogrid reinforcement at specified intervals.
Show answer & explanationAnswer & explanation
Correct answer: D. The wall requires geogrid reinforcement at specified intervals.
For any segmented retaining wall exceeding 4 feet in height, geogrid reinforcement is almost always required to provide tensile strength and prevent the wall from overturning or sliding. This is a critical engineering requirement for taller SRWs.
Why the other options are wrong
- A. SRW units are designed to be dry-stacked and rely on interlocking features and geogrid, not mortar, for structural integrity.
- B. A concrete bond beam is not a standard requirement for all SRWs and is typically used for specific engineering or aesthetic purposes, not general stability of a 6-foot wall.
- C. While footings are important, their specific width depends on engineering calculations, and 12 inches is not a universal rule for a 6-foot wall.
Segmented Retaining Wall (SRW) Reinforcement
Segmented retaining walls rely on their mass, interlocking units, and often geogrid reinforcement to resist lateral earth pressure. Geogrid is crucial for walls exceeding a certain height (typically 3-4 feet) to ensure stability.
- SRWs resist soil pressure through weight and interlocking.
- Geogrid provides tensile strength, tying the wall to the soil mass.
- Required for taller walls (e.g., over 4 feet) to prevent failure.
Memory trick: Walls over Four, Need Grid More!