Reinforced subgrade
Geotechnical
- Ground
- Shallow soft layer over competent
- Method
- Shallow testing to 3.0m
- Scope
- Geogrid and engineered fill
- Outcome
- Platform tested to spec
Soft ground under a building platform does not have to mean piles. Where the weak layer is shallow and the loads are spread, a reinforced subgrade will do the work, and the investigation is what tells you which case you are in.
Here the testing found a compressible layer close to the surface over competent material below. Geogrid was specified across the subgrade to spread load and tie the fill together, with granular fill placed and compacted over it in layers to a stated density.
Compaction was tested as the platform came up. A platform that is signed off on test results rather than on appearance is the difference between a floor that stays flat and one that argues with you later.
The grid is lapped at every joint so the reinforcement is continuous across the platform
Fill goes down in layers thin enough for the roller to reach the bottom of each one
Levels are held to the design platform so the fill depth is known, not estimated
The slab above is designed for the platform it sits on, once that platform is proven
