According to construction technology, bored piles with casing can be installed on their own on soils with different characteristics. They can be of any design and have different sizes. Due to the long rods, reliable engagement with the ground is achieved, so that the foundation of the pipes is stable and perfectly holds structures of any severity.
Pile design and installation method
The use of such metal pipes is practiced in the construction of oil and water wells so that soil from the walls does not crumble into the drilled hole. For the same purposes, a casing is used for the foundation of the piles, tightly entering the soil and holding it, thereby preventing a collapse. The technology of its installation is to install in sections fixed to each other by welding or using special clamps. At the end of all procedures, sections are subject to dismantling, however, in some cases they are left in the ground, which is noted in the construction technical documentation.
The device for immersing the casing elements is carried out by hydraulic jacks at the time of drilling operations using the rotational or shock method. The technology also allows you to clog pipes or install them using vibration dampers. The shock method consists in deepening the casing element into the soil after or before the bottom to the set level - here it all depends on the passage characteristics of the soil. The assembly of sections or their addition is carried out to the required number.
With the rotational method of drilling, the section is immersed in the leader well, created by the size of the casing elements, and so the process is repeated again until the casing is submerged to a predetermined mark. After the pipe is fully installed, it is necessary to clean the cavity of soil residues using the same drill. Here, Kelly’s rod will come to the rescue, which acts as a drill, but with the only difference being that under load its blades expand to set parameters, thereby increasing the efficiency of leading drilling of leader holes. At the time of weakening of the onset, the blades return to their original position, which coincides with the inner diameter of the pipe for bored piles. When lifting the drill, the auger throws the soil mass out of the cavity.
The device of casing bored piles
Installation and installation of the pile foundation is carried out directly at the construction site. In principle, the technology for installing such a design with your own hands is quite simple: you need to lower the pipe into the well, reinforce and concrete it. In length, such structures can be up to thirty meters with a diameter of up to one and a half meters, although with the improvement of technical support, the length can be doubled and the cross section increased to 3.5 m. With these parameters, the bearing capacity of the bored bearings will be 500 tons.
In most cases, the structure is buried by 5 - 12 m with a diameter of 25 - 40 cm. Assembling metal structures with your own hands is carried out according to the following scheme:
- Per meter, the well is filled with concrete;
- the solution is tamped;
- the casing gradually rises to the level when the concrete drops by 35 - 40 cm;
- this process must be repeated until the rod is completely filled with mortar.
The walls of the leader hole for the casing during drilling become rough and loose due to crumbling soil, therefore, a gap is formed between the hole and the metal structure, which is compacted with the solution, and concrete, in turn, seeps into the soil structure and makes it more durable. This technology has one drawback, and it consists in the fact that you can not control the density of concrete pouring inside a long barrel. This minus can lead to erosion by underground waters of non-seized sections of the mixture, if such, of course, exist.
A well under the foundation of pipes is reinforced only in the upper part, while the reinforcing cage is buried in fresh concrete by 1.5 - 2 m. Along with the casing, a dry method is also used, suitable for stable and dense soils that can withstand the load without breaking the walls. The frame is installed in the well with your own hands, and then the mortar mass is filled. If bored wells are recessed into weak, watery soils without casing, their walls must be strengthened with clay coating, the density of which should be at least 1.2 g / m3.
Other types of pipe piles
In the previous part of the article, we examined bored piles, but there are also other types of them. In private construction, screw rod mounting technology is very often used if lightweight construction is planned. Their advantage is that they are suitable for any soil other than rocky, although there can be drilled smaller wells. Moreover, such a foundation of pipes is easily installed using the rotation levers with your own hands. It can be mounted on the site of the old base and equipped with headrests, which is an undeniable advantage, because the wooden house can be lifted with jacks and installed on a new base.
There is a technology for extending the operational period of metal screw rods, for which they are turned into printed ones, and the cavities are poured with concrete, which must be compacted. This technique will help protect the supports from corrosion. Read more about screw pile foundations.
No less often than bored, arrange asbestos-cement foundations, which are additionally equipped with a buried or suspended grillage. They are mounted where the landscape is characterized by heaving soils. Here, the technology also provides for concreting cavities, which gives the basis of strength and increases its operational period.
Summarizing the above material, we can say with confidence that using concrete piles by adjusting the length of the rod, it is possible to solve the problem of laying the foundation on slopes, watery and landslide soils. But, despite the mass of advantages, it is worth remembering that bored piles during the installation process create vibration with a high amplitude, so they can cause damage to nearby buildings.