What is Pile Foundation? – Structures are supported by foundations, which also carry loads from the structure to the earth. However, the layer to which the foundation transfers the load must possess the necessary settling characteristics and bearing capacity. There are numerous foundation types based on various factors, including:
- Total weight imposed by the superstructure
- soil properties.
- hydration state.
- Sensitivity to noise and vibration.
- accessible resources
- the project’s timetable.
In general, there are two types of foundations: shallow foundations and deep foundations. When the carrying capability of the surface soil is sufficient to withstand the loads imposed by a structure, shallow footings are often utilised. On the other hand, various deep foundation types are typically employed when the surface soil’s bearing capability is insufficient to support the loads imposed by a structure. Therefore, the loads must be moved to a deeper level where the soil layer can support them better. One of the deep foundation kinds is the pile foundation. The use of piling in civil engineering is quite popular among foundation engineers. In this post, we’ll go through the definition and specifics of piling foundations.
A type of deep foundation known as a pile foundation is described as a long, thin column constructed of concrete or steel that is used to support a structure and transmit loads at appropriate depths using end bearing or skin friction.
Deep foundations are those made of piles. They are built out of long, thin, columnar parts that are normally made of steel, reinforced concrete, or occasionally wood. When a foundation’s depth is greater than three times its width, it is referred to be “piled.”
Large constructions and situations where shallow soil is unsuitable to resist uplift, excessive settlement, etc. typically need the usage of foundation piles.
Utilization of Pile Foundation
- The greatest option is foundation pilings when the groundwater table is high.
- Heavy and irregular loads are imposed by the superstructure.
- Other types of foundations are either too expensive or impractical.
- when the soil is compressible at shallow depths.
- when scouring is a possibility since it is close to a riverbed, the beach, etc.
- when a deep drainage system or canal is located close to the building.
- when unfavourable soil conditions prevent soil extraction from reaching the specified depth.
The foundation engineer must select a pile foundation for the project whenever one of the aforementioned circumstances (when pile foundations are appropriate) occurs.
Pile Foundation Types
Based on Use or Function
The friction pile uses the frictional force between its surface and the soil surrounding it, such as stiff clay, sandy soil, etc., to transfer load from the structure to the earth. Depending on the underlying layers, friction may develop over the full length of the pile or along a specific length of the pile. In general, the entire pile surface contributes to the transmission of loads from the structure to the earth in friction piles.
The pile’s capacity is calculated by multiplying the surface area by the safe friction force created per unit area.
LOAD BEARING PILES
The primary purpose of this kind of pile foundation is to transmit vertical loads from the structure to the ground. These load-bearing pile foundations transfer loads from a layer that is able to carry the load onto a layer of soil with weak supporting properties. Load-bearing piles can also be categorized as flowing depending on the method of transferring weight from the pile to the earth.
END BEARING PILES
The lower tip of the pile serves as a passageway for the loads in this form of pile foundation. The end-bearing piles’ bottom ends rest on a solid foundation of rock or dirt. The pile often lays between a weak and powerful slayer’s transition layer. The load is therefore safely transferred to the sturdy layer by the pile acting as a column.
The size of the pile’s tip and the bearing capacity at the specific soil level where the pile is buried may be multiplied to determine the overall capacity of an end bearing pile foundation. It is determined what the pile’s diameter should be by taking an acceptable safety factor into account.
The primary purpose of these piles is to offer lateral support. They often withstand lateral pressure from things like water flow and loose dirt. They are typically employed for shore protection, trench sheeting, and cofferdams. They are not employed to support the building vertically. They often provide the following function.
- Building retaining walls.
- Protection against erosion of riverbanks.
- Keep the loose dirt in the vicinity of the foundation trenches.
- For separating the foundation from nearby soils.
- To contain dirt and so boost the soil’s bearing ability.
SOIL COMPACTOR PILES
This kind of pile, in contrast to other pile foundation kinds, does not support any direct loads. These piles are driven at precise intervals to compress the soil and boost its bearing capacity.
Depending on the Construction Method and Materials
CONCRETE PILES :- Precast Concrete Pile, Cast In Situ.
Precast Concrete Pile
If they are rectangular in design, the precast concrete pile foundation is produced in a pile bed with a horizontal form. Circular piles are often cast in vertical configurations. Steel reinforcement is typically added to precast piles to avoid breakage as they are moved from the casting bed to the site of the foundation. After the piles are cast, the required curing must be carried out. Pre-cast piles typically require 21 to 28 days to cure.
Cast In Situ.
This kind of pile footing is built by drilling a hole in the earth to the necessary depth, adding newly mixed concrete there, and allowing it to cure. Cast in situ concrete pile foundations are built by either driving a metallic shell into the ground, filling it with concrete, and then either pulling the shell out as the concrete is being poured, or both. Cast-in situ piling frequently employs round piles.
The sorts of piled foundations that are buried beneath the water table are timber piles. They have a 30-year lifespan, roughly. They might have a round or a rectangular form. They can range in size or diameter from 12 to 16 inches. Typically, the pile’s length is 20 times its top breadth.
Typically, they are made to support 15 to 20 tonnes. Bolting fish plates to the side of the piles will increase their strength.
Steel piles can be made of hollow pipes or I-sections. They are concrete-filled. The diameter can range from 10 inches to 24 inches, and the typical thickness is 34 inches. The piles are simple to drive because of their tiny sectional area. Their primary use is as end-bearing piles.