The foundation based on screw piles is considered one of the most affordable in terms of financial costs and technical implementation. The installation method is so simple that it can be done without the help of professionals. However, depending on the scale of the project and the conditions for its implementation, auxiliary equipment may be required. Her choice is determined by the specific technology of mounting the supporting equipment. For example, in the question of how to install a small-sized screw pile, complex equipment may not be used at all, since two or three people will perform twisting with improvised devices. However, in the case of large rods, special technical means cannot be dispensed with.
In what cases is the pile foundation used?
According to the mechanical load-bearing abilities, this method of building the foundation of the house loses to the more traditional methods of forming monolithic and even strip foundations. Therefore, first of all, single-storey, prefabricated and other objects that do not involve heavy loads are erected on a platform with point-like structural holding elements. For example, frame houses on screw piles, which are characterized by durability and reliability. Often built and objects for technical purposes: baths, hangars, utility rooms, senniki, etc.
The nature of the local soil also influences the choice of technology. The same classic foundations with a monolithic structure are undesirable to use on such surfaces. However, metal rods neutralize the loads associated with the dynamic processes of the soil layer, which makes them an attractive solution for such operating conditions. The modest cost is also an additional attractive factor in the choice of screw piles for the foundation. Prices with installation on average are 1,500-2,000 thousand rubles. for 1 pc. Moreover, as a rule, ordering material with installation work from the same supplier reduces the cost of the rods by 100-200 rubles.
Screw pile design
Typical elements are hollow pipes, on one side of which there is a head, and on the other, a pointed tip with a threaded blade. The part, which is designed for immersion in the ground, has an anti-corrosion coating, due to which the durability of the structure can reach 40-50 years. As for the functional tip, it can be made in different ways. The main distinguishing feature is the number of turns, on which the force exerted on the rod will depend. Least of all the power costs are the elements with a small area of the cutter, but how to install a screw pile, provided with many turns? Special equipment usually works with such models. The machine captures the ground part of the rod and spins it into the ground. On the one hand, this approach complicates the installation process and makes construction more expensive, but on the other hand, the more turns, the stronger the bearing base, that is, at all costs, the user will receive a foundation design that is optimal in quality.
Calculation of screw piles
Despite the initial choice of this type of foundation for objects with minimal loads, this does not mean that the number of rods and the configuration of their placement can be any or universal for all cases. These parameters depend on the specific indicators of the planned load. The total weight consists of the mass of walls, floor coverings, partitions, roofs, equipment, etc.
Calculation of screw piles provides for the inclusion of a safety factor: to the combined loads of individual elements is added about 10-15% of the safety endurance of the structure. Further, the ability to cope with the loads of one rod is taken into account. A typical model can take on the order of 2000 kg. Initially, the calculated mass of the house is divided by this figure and the result will show what the optimal number of piles will be. For example, for a small house weighing 20,000 kg, 10 load-bearing elements will be required. You can add another rod to cover the safety factor. As for the placement configuration, it will depend on the area of the house, as a rule, an indentation scheme of 2 m is taken between installation points with the obligatory capture of the corners of the structure.
Preparing for work
After the purchase of piles, a thorough examination of their appearance is necessary. Particular attention is paid to the reliability of fastening the blades to the main part. If necessary, the structure is additionally welded with the addition of a melt increasing strength. But how to install a screw pile, if foreign functional elements are present in the functional part? First, even at the stage of refinement of the underground area, the area of deviations of the same melt from the main surface of the rod should be minimized by mechanical refinement with a grinding and polishing tool with large grain. Secondly, the twisting process itself in this case should be adjusted. The operation should be performed at low speed, constantly monitoring the geometry of the introduction of piles.
Hand screwdriving
Most often, a double-lever system is used, which allows you to completely dispense with special equipment, but at the same time provide sufficient force to immerse the rod. Another thing is that this twisting mechanism can only be used in relation to small or medium screw piles for the foundation. Do-it-yourself installation in this case is implemented as follows:
- In the area of the head, ears are welded on which elements of the direction of effort will be fixed in the future.
- Metal beams (levers) are laid in the created holes and are held from opposite sides by two workers.
- Directly at the point of twisting becomes a controlling operator with an electronic level.
- Lever control workers begin to move with a leverage until the target immersion point is reached.
- The operator with the level throughout the process controls the vertical rotation.
The double-lever mechanism with a head grip is the simplest device for screwing screw piles, but it has certain disadvantages. First of all, you need free space around the dive point. In addition, in the event of a deviation from the intended input line, there is a risk of deformation of the rod or of an error in the arrangement of bearing points of the foundation.
Electromechanical screwdriving technology
This option is suitable in cases where there is no special equipment or partners. The force is applied using the multiplier. It is a gearbox with optimized planetary gear. The device is mounted on the working equipment of a high-power drill, after which it is installed on a supporting platform fixed near the screw pile. Installation technology is carried out by rotating the gearbox head. Fast working torque is converted to slow but steady torsion with a large range of applied force.
Screwing piles with special equipment
In professional construction, mobile power tools using electric traction or ICE engines are used. They can be used in everyday life. Another thing is that this rarely makes sense, since such a technique focuses on large-format rods, the width of the blades of which can exceed 60 cm. However, small-format elements are not excluded from the target material for such machines.
How to install a screw pile using a mobile installation? The equipment is brought to the installation point at a distance of 1-2 m. The working body is integrated with the pile head, after which a strictly vertical direction of force supply is established and the twisting process is started.
Subsequent operations of the pile foundation
After installing the rods, they are trimmed and concreted by the site. As for the first operation, it is associated with the alignment of the positions of the piles in height. This is necessary so that in the future it is possible to obtain an even base on screw piles without the need for corrective additions, then concreting is performed. This is a standard concrete pouring procedure for the foundation base, but it should be borne in mind that the screed obtained is not related to the supporting platform of the building.
Pros and Cons of Technology
Actually, the installation technique is the strength of this method of arranging the foundation. An ordinary private trader can also cope with this task by calling two or three partners for help. The specific technique for performing the operation depends on which screw piles are used for the foundation. Do-it-yourself installation of small rods can very well be done using the double-lever method, which practically does not require costs, but involves some risks in terms of quality of the result.
The disadvantages of using piles include restrictions on the use on solid soils and the inability to build two-story and simply large private houses on such a base.
Conclusion
The technology has been chosen by many owners of suburban households because of its affordability. It makes it possible, with small investments, to create a reliable foundation for various functional buildings, cottages, etc. Nevertheless, much will depend on the type of screw piles for the foundation itself. Prices with installation for thin models designed for the construction of a bathhouse or utility room can fit in 1300 rubles. For 700-800 rubles. a pile will be available, and at 500-600 rubles. Direct installation will cost. For full-length material, these figures can increase by 20-30%. To this, it is worth adding small expenses for additional accessories, for example, heads cost 200-300 rubles, and their installation costs from 50 to 100 rubles. average.