[Solved] Raft foundation is useful where (2024)

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[Solved] Raft foundation is useful where? ›

To sum up, raft foundations are good for spreading the weight of a building evenly over a bigger area. They are better for places where the ground is not very strong and the building is heavy. They can also help stop damage to the building.

The principal aim of a raft foundation is to spread the load of the building across the entire available surface area under the building. This reduces the stress on the ground below, providing a solid foundation that can accommodate ground movement whilst still maintaining structural integrity.

Raft foundation may be used under the following conditions: The soil has a low bearing capacity. The load of the structure has to be distributed over a large area. Individual or any other foundation area would approximately cover 50% of the total ground area beneath the structure.

Raft foundation is generally used to support structures like residential or commercial buildings where soil condition is poor, storage tanks, silos, foundations for heavy industrial equipment etc.

Cellular raft foundations offer several advantages, making them a viable choice for challenging soil conditions. Firstly, they provide excellent load distribution, reducing the risk of differential settlement and potential structural damage.

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.

Advantages of using a raft foundation include reduced settlement and improved bearing capacity. Disadvantages are not mentioned in the provided information. The advantages of using a raft foundation include increased load bearing capacity and suitability for high water level areas with poor bearing capacity.

2. One should not place it on topsoil. 3. Mat foundation must be at least 50 cm deep according to IS 1080, which is necessary to ensure the soil's safe bearing ability, which is assumed by design.

Additionally, raft foundations can be more expensive than other types of foundations, as they require a large amount of concrete and steel reinforcement. In conclusion, raft foundations are a type of shallow foundation that is ideal for large commercial or industrial buildings, bridges, and high-rise structures.

What are examples of raft foundations? ›

There are four main types of raft foundation: solid slab rafts, slab beam rafts, cellular rafts and piled rafts.

Shallow Foundations vs. Deep Foundations

In contrast, deep foundations (usually piles) are used when the soil is weak or unstable, and the building's weight needs to be supported by deeper, stronger soils or rocks.

A raft foundation is a type of shallow foundation that spreads the load of a high-rise building over a large area, reducing the stress on the soil and avoiding differential settlement. Raft foundations are suitable for sites with low bearing capacity, high water table, or complex soil conditions.

There are three main foundation types: full basem*nt, concrete slab, and crawlspace. While basem*nts are a great fit for colder regions such as the Northeast and Midwest, concrete slab foundations are often the popular choice in Southern states where high water tables pose a flooding risk for underground construction.

3 Soil conditions

Based on the soil properties, you can calculate the bearing capacity, settlement, and stability of the foundation. Generally, pile foundations are preferred for soft, loose, or heterogeneous soils, while raft foundations are preferred for hard, dense, or hom*ogeneous soils.

In a raft foundation detail the entire structure is poured in one process. Raft foundations will generally require a substantial amount of additional formwork and steel reinforcement over and above a standard strip foundation making them more expensive.

Slab on grade pours are on well compacted, water flow suitable subtrade and typically hold only a light structure. Raft foundations are typically excavated sites, whereby the entire perimeter, sides, and base are poured seamlessly together to form a raft that a heavier structure can rest on.

The main difference between a raft foundation and a spread footing is the way in which the load is distributed. A raft foundation spreads the load evenly over a large area while a spread footing distributes the load to specific points.

A raft foundation, or mat foundation, is a type of slab-on-ground foundation used in both residential and commercial construction. Raft foundations generally don't require excavated footings and are formed 'on the ground' rather than being dug in. The raft 'floats' over the ground, the way a raft floats on water.

3 Soil conditions

Based on the soil properties, you can calculate the bearing capacity, settlement, and stability of the foundation. Generally, pile foundations are preferred for soft, loose, or heterogeneous soils, while raft foundations are preferred for hard, dense, or hom*ogeneous soils.