In which type of soil 'Floating foundation' can be used?

As per my experience I would suggest you to use floating foundation in the following situation.

1. When shear strength of soil is more and having a problem of large displacement or settlement then we can use floating foundation for reduction in settlement or displacement.

• When the soil strata is so soft that even pile friction is not enough for handling the load generally for tall buildings.
• When there is a presence of expansive soils from the surface down to a considerable depth. Like the depth of the floating foundation itself.
• Other cases when there is a good shear strength but a large settlement issue.
• Cases where there is a low shear strength and there is no hard layer present until a considerable depth.

As per my opinion the floating foundation is

When the soil is so soft that even friction piles will not support the building load, the final option is the use of a floating foundation making the building like a boat that obeys Archimedes’ principle—it is buoyed up by the weight of the earth displaced in creating the foundation. Floating foundations consist of flat reinforced slabs or mats or of reinforced concrete tubs with walls turned up around the edge of the mat to create a larger volume.

And where there are other combined footing can also be designed to carry the overall structure load, but the area covered by those combined footings are more than 70% then we choose to use floating or raft foundation to minimize the discrepancies in the case of combined foundation very near to each other.

As per my knowledge, floating foundation can be used in moisture soils. Floating foundation are used in low bearing capacity soils.

Floating foundation can be used in on high moisture soils.