When shallow foundations cannot be used to create the structure, pile foundations are built. The decision to use piling foundations is made as described in the article, depending on the kind of construction and other factors.
See also: What is foundation: All you need to know
Piling foundation: What is it?
It is a style of foundation that is built deeply into the earth, primarily using circular pieces.
The vertical loads are sent directly to the soil by the shallow foundations, which are supported by the earth. If the applied pressure is less than the permitted bearing pressure, the geotechnical design is acceptable. The capacity of the soil is indicated as the allowable bearing capacity.
However, distinct techniques and specifications are employed in piling foundations.
The design takes into account soil skin friction (both positive and negative), weathered rock skin friction, rock skin friction, and the end bearing of the rock.
Piling foundation: When do pile-supporting structures need them?
- When weak foundations with poor bearing capacity are unable to support the vertical loads placed on them.
- When the soil contains peat or other thin soil layers
- To support the foundation’s tensile pressures. To carry tensile stresses, piles can be fastened into the rock.
- To support compressional lateral stresses placed on the foundation. Both the compression and tensile pressures will be supported by an inclined pile.
- Soil-bearing capacity is insufficient to support such loads when vertical loads are very high, particularly in tall structures. We require plenty.
Piling foundation: Factors affecting pile foundation design and construction
- The superstructure’s loads
- State of the soil. The amount of skin friction will vary depending on the kind of soil. Negative skin friction must be taken into account while designing the pile’s geotechnical foundation in peat-like soil layers.
- State of the rock. The borehole-derived RQD and CR values have a significant impact on the pile capacities.
- When using piles as a supporting system, the cost of construction is another important aspect to take into account.
- The site’s accessibility needs to be examined.
- Checking of clearances from the borders
- It is necessary to evaluate the vibration and sound level limitations. A vibration that is too intense might harm nearby homes.
Piling foundation: Types
01. Cast in situ piles or bored piles
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Bored piles are large, cylindrical concrete columns that are installed into the ground to provide support for structures. They are used in a variety of applications where the soil is not strong enough to support the weight of the structure or where the structure requires a deep foundation to reach stable soil layers. Some common applications where bored piles are used include:
Bridges: Bored piles are often used to support bridges, particularly in areas with soft or unstable soil. They provide a deep, stable foundation that can withstand the weight of the bridge and its traffic.
High-rise buildings: The deep foundation provided by bored piles helps to ensure the stability of the building and reduce the risk of settling or sinking.
02. Precast/ driven piles
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These piles are prefabricated.
When compared to bored piles, they are built when the applied load is relatively modest.
Driven piles are long, cylindrical members that are driven into the ground to offer support for structures. They are typically made of steel, concrete, or timber and are used in applications where the soil is not strong enough to support the weight of the structure. Some common applications where driven piles are used include:
High-rise structures: Drilled piles are frequently used to support high-rise structures, particularly in regions with brittle or unstable soil. The building is more stable because of the deep base that driven piles offer.
Marine structures: Jetties, wharves, and breakwaters are all examples of marine constructions that are frequently supported by driven piles. They are made to be resistant to the effects of erosion and wave action and to provide these constructions with a solid base.
03. Micropiles
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Micro piles, also known as mini piles, are small-diameter piles that are used to provide support for structures in difficult ground conditions. They are commonly used in areas where the soil is weak, and conventional pile foundations are not possible. Some common applications where micro piles are used include:
Slope stabilisation: Micro piles are often used to stabilise slopes, especially in areas with weak or unstable soil. They provide a deep, stable foundation that helps to resist the forces of sliding and collapse.
Seismic retrofitting: Micro piles are used to reinforce existing structures, particularly in areas prone to earthquakes. They are installed deep into the ground to provide additional stability and support for the structure.
Deep foundations: Micro piles are also used in deep foundation applications, where conventional piles may not be feasible due to limited access or space constraints.
04. Sheet piles
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Sheet piles are long, narrow sections of material that are driven into the ground to provide support for structures. They are typically made of steel or other materials and are used in applications where retaining walls or excavation support is required. Some common applications where sheet piles are used include:
Retaining walls: Sheet piles are commonly used as retaining walls, especially in areas where excavation is required. They provide a cost-effective and flexible solution for retaining soil or water, and can be removed and reused after excavation is complete.
Flood defence: Sheet piles are also used in flood defence applications, where they are used to construct temporary or permanent flood walls. They provide a strong and durable barrier to protect against water damage.
Marine structures: Sheet piles are used in marine structures, such as jetties and quay walls. They provide a strong and stable foundation that can resist the forces of wave action and erosion.
05. Timber piles
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Timber piles are cylindrical members made of wood that are used to provide support for structures. They are commonly used in applications where a deep foundation is required and where the soil is not strong enough to support the weight of the structure. Some common applications where timber piles are used include:
Wharves and jetties: Timber piles are commonly used in wharves and jetties, where they provide a strong and durable foundation that can resist the forces of wave action and erosion.
Retaining walls: Timber piles can also be used to support retaining walls.
06. Screw piles
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Screw piles, also known as helical piles, are long, cylindrical members with a helical plate that are screwed into the ground to provide support for structures. They are used in applications where a deep foundation is required and where the soil is not strong enough to support the weight of the structure. Some common applications where screw piles are used include:
Residential and commercial construction: Screw piles are often used in residential and commercial construction. They provide a deep, stable foundation that can support the weight of the structure and reduce the risk of settling or sinking.
Decks and patios: Screw piles are also used to support decks and patios, where they provide a strong and stable foundation that can resist the forces of wind and water.
Renewable energy: Screw piles are used in renewable energy applications, such as wind turbines and solar panels, where they provide a deep, stable foundation that can withstand the weight and movement of these structures.
Piling foundation: Advantages
- Pile foundation benefits include the ability to pre-prepare heaps based on length.
- Precasting speeds up the finishing process.
- It may be set up across a huge region and over extremely long distances.
- Piles can be utilised in a location where drilling is not necessary.
- The heaps are tidy and spotless.
Piling foundation: Disadvantages
- Pile-based foundations have the drawback that they are easily destroyed when driven through by rocks and boulders.
- Marine borers may damage piles in seawater.
- A pile cannot be raised above the surface.
- It is exceedingly challenging to determine the precise length needed in advance.
- When the piles are driven, vibrations are created that have an impact on nearby structures.
- Piles must be operated with powerful machinery.
FAQs
What is a pile foundation?
A pile foundation is a type of deep foundation used to support heavy structures, such as buildings and bridges, by transferring their load to deeper soil or rock strata with sufficient bearing capacity.
What is the purpose of a pile foundation?
The purpose of a pile foundation is to provide a stable and secure base for a structure by transferring its weight to deeper, more competent soil or rock strata.
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