Under what situation raft foundation is adopted?
Under what circumstances raft foundation is adopted? Raft foundation is used where settlement above highly compressible soils, by making the weight of the structure and raft approximately equal to the weight of the soil excavated.
What does raft mean in English?
noun. a more or less rigid floating platform made of buoyant material or materials: an inflatable rubber raft. a collection of logs, planks, casks, etc., fastened together for floating on water.
Is raft foundation shallow or deep?
Raft foundations are a type of shallow foundation. They are typically formed by reinforced concrete slabs that cover a wide area, often the entire footprint of a building.
What is a raft foundation used for?
A raft foundation is a reinforced concrete slab under the whole of a building or extension, ‘floating’ on the ground as a raft floats on water. This type of foundation spreads the load of the building over a larger area than other foundations, lowering the pressure on the ground.
Is a raft foundation expensive?
Raft foundations are relatively inexpensive and fast to put down, when compared with other types of foundation. Ground excavations are less onerous than for trench excavations, for example, and the foundation and floor slab can often be combined, giving significant savings on materials and time.
How do you build a raft foundation?
The maximum settlement should generally be limited to the following values: Raft foundation on clay – 65 to 100 mm. Raft foundation on sand – 40 to 65 mm.
2) Soil line Method (Elastic Method) of Raft Foundation Design.
|1. Stiff||1 to <2||2.7|
|1. Very Stiff||2 to <4||5.4|
|3. Hard||4 and over||10.8|
What is a compensated raft foundation?
Compensated raft foundation is used to support heavily loaded structures resting on soft and low-permeable soils. … Such soils often require pre-loading and pre-treating with vertical drains to arrest the majority of the final settlement under the actual construction in less time.