Piles are designed for the manufacture of foundations for structures and buildings in order to transfer the load to the ground, as well as to increase its bearing capacity. The foundation is distinguished by durability, ease of arrangement and low cost. Types of piles depend on the material used, manufacturing technology, shape and driving method.
The difference in assortment lies in the materials used and immersion technologies. In this case, the installation of piles depends on the properties of the material and design features. The following types are distinguished by materials:
- reinforced concrete or concrete piles;
- wooden;
- metal.
Classification is also made according to the methods of their immersion in the ground, directly related to mechanical properties and design features.
Piles: types of immersion
Piles of any material are divided into hanging and racks. The former are used for weak soils of great depth. They transmit the load not only by the lower end, but also by friction between the ground and the sidesurface. Racks rest with their lower end on a solid base that takes the entire load.
Structures of piles are interconnected with the method of immersion and are of the following types.
- Drive-in - with the help of hammer blows, using vibrators or indentation devices. The method is used if there are no other structures nearby that can precipitate from ground shaking.
- Hollow piles-shells. They are immersed in the ground by means of vibration, removing the soil from inside and replacing it with a concrete solution.
- Drilling - wells are drilled and filled with a mixture of concrete with reinforcement or a reinforced concrete element.
- Stuffed - a well is made by compressing the soil and pouring concrete.
- Screw - screw into the ground.
Piles of wood
Wooden foundation is used for light houses, in which the weight per 1 m2 area is below the norm. It is erected for buildings with the same service life. Usually these are temporary and outbuildings, small shops, car washes, cafes. Such structures do not require expensive approvals required for capital structures.
Types of wood piles are classified according to the type of lumber used to make them. They are made from pine, spruce, cedar, larch, oak, etc. Logs are taken straight and cleared of bark. Piles are made from 4.5 to 16 m long and 20 cm in diameter. If the deepening is significant, wooden piles are built up to a maximum of 4 elements. Bottom end grindon a cone, the length of which is equal to 1.5-2 trunk diameters. If the soil is too dense or with solid inclusions, a metal shoe is put on from below. The upper end is protected with a metal ring (yoke) to protect against deformation when driving in.
Before immersion, the piles are impregnated with anti-rotting compositions: special coatings, firing. Then they are additionally coated with creosote oil or tar and wrapped with antiseptic bandages.
Under the foundation pillars, wells are usually drilled 1.5 times larger in diameter. From below, stones or concrete mixture are used for support. After installation, the pillars are buried and tightly tamped. When properly processed, wooden piles last up to 20 years.
Reinforced concrete piles
Piles can be delivered to the site ready-made, in the form of beams, or poured into formwork mounted in a drilled hole.
Types of pile construction can be round or polygonal, with pointed lower ends. The length reaches 16 m, the size in cross section is from 20 to 40 cm.
The most common products are square sections, as they are less labor-intensive and more technologically advanced to manufacture.
Pile foundation, types of piles
The foundation is created from a group of piles connected from above with beams or slabs (grillages). A single pile can withstand a significantly lower load compared to the weight of the above-ground structure. Therefore, the supports are formed into groups.
1. Monolithic piles
Before scoringpile into the ground, first a well is drilled in it at a depth of 1.5 m, into which a column is inserted. Then a crane with a hammer or a pile driver is brought in and driven to the required depth. The free space of the calibration hole is filled with concrete.
Hollow piles made of reinforced concrete consist of links connected by welding or bolts. In their lower part, the soil remains, and concrete mortar is poured into the upper part to provide a connection with the foundation.
2. Bored piles
Types of foundation piles also include structures made directly at the construction site.
The bored support is made as follows.
- A well is made in the soil to the depth of the pile. To do this, the soil is drilled or punched. In the first method, the soil walls can be strengthened with casing pipes or clay mortar. When the bottom mark is reached, the space under the base is expanded with a special device mounted on a drill rod.
- A roofing material pipe and a formwork of four reinforcement bars with horizontal bandages are inserted inside the well.
- The interior space is filled with concrete mortar and compacted with a vibrator.
Metal piles
Rolled profiles are used as piles: I-beam, channel or pipe. Sometimes they are pre-prepared. To do this, 2 channels are welded together, thus obtaining a square pipe.
Piles can also be of open section. They are made up by welding corners, rails,I-beams.
Metal is used in cases where it is impossible to install reinforced concrete piles. It is easier to build up as you go deeper into the ground.
Metal profiles have high strength, which makes them easy to drive into the ground. For a small cross-section, solid inclusions or broken rocky soils are not afraid.
Piles are driven into the ground with a hammer or press. For depths up to 5 m, a hand hammer is sufficient.
Special types of piles among metal products are screw. Providing high strength, they are more economical and more technologically advanced than reinforced concrete foundations. Piles are hollow pipes with external blades. They are screwed into the ground like screws, preserving its structure and additionally compacting. In this case, reverse rotation is not allowed, so as not to degrade the characteristics of the base.
Advantages of screw piles
Screw piles have the following advantages:
- lack of earthworks;
- possibility of housing construction on difficult terrain and soft ground;
- easy to attach to ready-made architecturally formed sites;
- high bearing capacity;
- no shrinkage;
- possibility of installation near utilities and at any time of the year;
- durability.
The foundation of screw piles is used on soft soil, where high humidity, freezing and fluidity. It will not be possible to build a basement with it, but this drawback is typical for all types of pile foundations.
When choosing screw piles, you shouldpay attention to the following factors.
- The basis is a new steel pipe with sandblasting and a reliable anti-corrosion coating. The wall thickness must be at least 4 mm, and the blades must be more than 5 mm.
- The outside of the pipe must be smooth, without protruding welds, and the blade must be of the correct shape.
- The quality of welding is high, otherwise the connections will not withstand when screwed into the ground.
There are the following types of screw piles:
- cast, high-strength blade-to-pipe connection;
- welded - with welding of the blades on the pile body;
- combined, assembled from two parts - blades with a cone.
Screw piles are not mounted in rocky and stony ground, although there is special equipment for such installation.
Installation of screw piles
- The appropriate pile size is selected based on the calculation and analysis of the soil.
- The marking is made, and the pile is installed in the required place.
- Screwing is done with a special technique, but sometimes it can be done manually, using levers. The work is carried out by 2-3 people. Depth should not be less than 1.5 m.
- The pile field is cut one level at a time.
- Concrete can be poured inside the pipes.
- Headers are welded on top of the piles, and then they are tied with a channel or logs. Welding seams are coated with mastic against corrosion.
Conclusion
Technologies for the use of piles inconstruction make it possible to solve complex problems of erecting buildings and structures in simple and affordable ways. Diverse types of piles, unlike other foundations, allow the development of underground spaces in any soil and in built-up areas.
