Foundation settlement is the major problem faced by geotechnical engineers. If the settlement is severe, it may lead to the complete collapse of the structure even though the factor of safety against shear failure is high. There are many techniques or ways to reduce the foundation settlement, the floating foundation is one of the best solution.
The total vertical displacement that occurs at the foundation level is known as “Settlement”. Low bearing capacity of soil, poorly compacted soil, soil consolidation are the reasons for foundation settlement. Floating foundation causes zero settlement to the structure and provides the stable platform for the superstructure.
About Floating foundation:
A floating foundation is a type of foundation constructed by excavating the soil in such a way that the weight of structure built on the soil is nearly equal to the total weight of the soil excavated from the ground including the weight of water in the soil before the construction of the structure.
The main aim or purpose of the floating foundation is to balance the weight of removed soil by a structure of same weight which causes zero settlement to the structure. For this reason, it is also termed as balancing raft foundation.
Selection criteria for floating foundation:
Floating foundations are suitable for the following conditions,
Soils having the problem of large settlement and differential settlements under heavy loads. In such cases, floating foundations reduce the values to a greater extent.
Soils having low shear strength and there is no hard layer available at reasonable depth. In this type, the floating foundation helps to reduce the shear stress.
Difficulties in the construction of a floating foundation:
During the construction of the floating foundation, some problem may arise, which can be prevented by taking proper care. The problems arise during,
Exacavation:- The excavation for the foundation has to be done with care. The side of excavation should be supported by sheet piling.
Dewatering:- Care has to be taken to see that the adjoining structures are not affected by dewatering process.
Bottom heave:- Excavations for foundation reduces the pressure in the soil which results in the heaving of the bottom of the excavation. Heaving can be minimized by phasing out excavation in narrow trenches and placing the foundation soon after excavation.
Advantages of floating foundations:
Used for low bearing capacity soils.
Minimizes the foundation settlement.
Floating foundations can be used in on high moisture soils.
Requires very less digging because deep footer trenches are needed.
Most suitable for heavily used highways.
The floating foundation is the best choice for geotechnical engineers to minimize the foundation settlement problems.
Kit required to develop Floating Foundation: