Piles are generally long and slender elements used to transport foundation loads through low-bearing-capacity soil layers to deeper, higher-bearing-capacity soil or rock. The process through which this occurs serves as the foundation for the most basic pile type categorization. Pile groups such as rock, earth, and concrete are used to describe the type of material used to construct the pile body. These categories indicate how the pile is intended to be employed within the structure it supports. For example, if a structural engineer were to recommend the use of rock piles to provide lateral support for an earthen dam, then that would be a classification of pile group: rock.
The load capacity of a pile depends on its length, diameter, number of times it is driven into the ground, and the soil resistance it encounters while being driven. Longer, thicker, and more frequently driven piles carry greater weight than shorter, thinner piles. Rock piles usually have a lower strength-to-weight ratio than other pile types because they are typically larger in diameter and made of stone, rather than steel or concrete. Earth piles are commonly used for temporary work because their weight does not exceed 10% of the total bearing capacity of the soil they are placed in. Concrete piles are the strongest of all pile types and can withstand a maximum load equal to their design strength. They are also the heaviest, so only a small number are required to support a given weight.
Pile foundations are primarily utilized to transmit loads from superstructures to stronger, more compact, less compressible, and stiffer soil or rock at depth, increasing the effective size of a foundation and resisting horizontal stresses. Pile-supported structures tend to be more resistant to overturning because they distribute loading over a large area of contact with the ground.
The term "pile" can be applied to anything that increases the surface area of contact with the ground and transmits loadings from above to below this object, including trees, rocks, buildings, etc. The word "pile" comes from Latin pila, meaning "ball". A "pile of stones" might be used to make a marker or boundary line.
People have been using piles to support structures over thousands of years. Early civilizations such as those in Egypt and India used logs or stones as piling. With industrialization, metal piles were used instead. Today's building practices include the use of concrete piles. They can be solid cores within the foundation wall or they can be open holes with steel reinforcing bars inside them. Whichever type is used, the purpose is the same: to provide an anchoring point for the foundation that transfers loadings from superstructures to deeper soil or rock.
In building construction, a pile is a post-like foundation element that has been utilized since prehistoric times. Piles of timber, steel, or concrete are driven into the ground to support a structure in modern civil engineering; bridge piers may be supported by groups of large-diameter piles. The word "pile" comes from the Latin pila, meaning "small stick". In architecture and town planning, a pile is one of several supporting elements for a building or structure. It can be as simple as a stake placed in mud to keep out water or a more elaborate arrangement such as those used to support bridges.
The earliest evidence of human use of timber piles dates back to 3250 BC in Mesopotamia. By 500 AD, piles were being used in Europe. The Chinese are said to have invented concrete in about 220 BC but it was not until much later that this technology emerged in the West. Concrete piles first appeared in France around 1770. They are now commonly used in buildings across the world.
There are two main types of piles: stabilizing and supportive. Stabilizing piles are placed close together in clusters to form a stable platform. They are used where weight loading is significant but there is no requirement for long-term stability. An example would be a platform for a building site. Supporting piles are placed further apart and hold up structures that require permanent stability. They are usually made of concrete with an internal core of wood.
A pile foundation is a sort of deep foundation in which weights are transferred to a lower level by vertical wood, concrete, or steel. Caisson is submerging a box and pouring concrete over it. A pile is a material column propelled by a piledriver. These days, cranes are used instead.
Piles were originally used in urban construction when shallow foundations would not do. They can be made from wood, steel, or concrete and range in size from small posts for ornamentation to large structures such as bridges. An excavator or backhoe is used to create a hole in the ground for the pile to go into. The top surface of the hole is then smoothed out and compacted. The area around the base of the hole may be filled with cement or other material to prevent soil from moving into the hole while it is being driven.
The term "pile driver" is often used interchangeably with "piledriver", but this is incorrect. A pile driver is a tool used to drive piles. There is also a human equivalent called a pile-driver operator who drives pilings using heavy machinery such as a backhoe.
Pilings are used in building work to provide support for floors, roofs, and walls. They can also be used as decorative features in their own right.
Piles are driven into the earth to provide a stable foundation for constructions placed on top of them. Loads are transferred from buildings to hard strata, rocks, or soil with a high carrying capacity through piling. The piles provide structural stability by being firmly embedded in the earth. They can also be used as decorative features or for outdoor furniture.
Piles should be made of pressure-treated lumber because untreated wood will rot if it contacts water. The wood should be clean, free of paint and other chemicals, and have no defects such as cracks or holes. Piling wood that has been treated with a chemical preservative will be OK if there is no contact with water; however, it should not be immersed in water because this will allow the chemicals to leach out and damage surrounding material.
The proper length of pile depends on several factors such as the load it will support and its proximity to structures or underground utilities. If possible, check with an engineer or architect to ensure that the length of pile you propose will adequately support whatever structure is going to be built onto it.
Generally, the deeper the hole, the longer the pile should be.
End-bearing piles and friction piles are the two forms of pile foundations. Both are made out of huge, robust columns that are bored deep into the earth. Friction piles rely on their resistance to gravity and do not require any additional support from beneath them. End-bearing piles need to be supported at their end to prevent them from pushing up against their surrounding soil.
The size of both pile types can vary considerably. The most common sizes for end-bearing piles are 10 feet and 12 feet while friction piles tend to be slightly smaller since they don't need to resist as much weight. Piles this size are capable of supporting a lot of weight without failing under normal conditions. There are also larger pile types available for special applications. For example, "superpiles" are 20 feet or more in diameter and support up to 500 pounds per square foot.
End-bearing piles work by drilling holes down to the desired depth then driving the pile into the ground until it reaches its bearing strength. The headroom left under the house is then filled with rubble or dirt and grassed over. This is called an "open" foundation because you can see how it's being held up by the building above it. Open foundations are easy to inspect for problems such as cracks in the surface soil.