screw pilesRaft Foundations
Where ground is not suitable for screw piles, driven piles or micro piles, FLI can design and install raft foundations to support both light and heavy weight structures, in Railway, Highway, Telecommunications or construction markets.
Raft foundations traditionally consist of a reinforced poured-concrete slab. Depending on the project, a raft foundation may also be stiffened by incorporating reinforcing bars or beams, with holding down anchors pre installed for attaching the structures. For certain purposes, concrete caps can also be complemented by additional foundations such as helical screw piles.
Use of screw piles with concrete rafts
Combing a raft and piled foundation is becoming increasingly more popular as it is a cost-effective solution where very soft ground is overlying hard ground at depth. It reduces the environmental harm and has safety advantages such as when trying to avoid deep excavations. As part of a range of foundation designs and construction services, FLI can provide foundation solutions to suit the site and the structure loadings.
Raft Foundation Variations
Plain concrete Raft foundations are suitable for light and heavy structures when the ground is suitable, however, if the ground is unsuitable for a concrete Raft, FLI Structures has designed the following solutions to overcome this problem -
- Plain slab with reinforcing bar
- Plain slab with separate wide strip foundation
- Plain slab with stiffened edge (and a deeper integral beam)
- Cellular raft foundations
- Piled raft foundations
- Piled ground beams
Advantages of raft foundations
- Loads are spread over the whole area of the structure.
- Differential settlements are reduced.
- A concrete raft foundation avoids interaction of individual pad foundations (e.g. for columns) where these would otherwise be too close together.
Disadvantages of raft foundations
- Particularly expensive to cart away and dispose of spoil from brown field sites.
- Is not cost effective on sloping sites, or where the ground is particularly soft.
- Piled solutions are more environmentally friendly
- Is time consuming foundation solution as curing times can be up to 4 weeks long
For more information, please contact us.
