Everyone knows that the bearing capacity of screw piles is an important indicator, thanks to which you can determine what level of load the foundation can withstand. This takes into account the negative impact of the soil on each support separately. Screw pipes are divided into two types:
- Hanging - have a support, which is located under the lower rings of the screw. Such supports are used in the construction of houses on soft soils. These designs have the ability to withstand strong loads by generating friction forces. It can appear between screw pipes and soils. If there are dense layers of soil on the site, there is no point in installing additional supports.
- Support type - used in areas with hard ground for the construction of houses. They play the role of an intermediary in transferring the load from the house to the foundation.
Before installing such a foundation, you should find out what bearing capacity of screw piles is required for construction.
Nuancesinstallation
In most cases, the bearing capacity of screw piles often depends on the size and diameter of the support. The screw base can be mounted in two ways:
- manual;
- using special technique.
The bearing capacity does not depend on the type of installation. Both installation methods are carried out according to the principle of screwing a screw pipe into the soil structure. This action is easily performed thanks to the blades that are located on the bottom of the support. In order not to worsen the bearing capacity, in some situations, the installation of a screw pile is performed differently:
- Installation of the screw support into the soil, which has a hard structure, as well as into the frozen ground. It is mandatory to drill small wells. This action will ensure that the screw post is safely screwed into the ground.
- If flooded soil prevails at the construction site, the surface of screw piles must be additionally treated with an anti-corrosion agent. A concrete mixture must be poured into the body of a metal pipe. Due to this, the strength of the foundation material will increase, and its service life will be extended.
If additional reinforcement is required, piles that are more than 2 meters long should be reinforced. This will increase the bearing capacity of screw piles around the entire perimeter.
It is important to know that it is possible to make correct calculations of the bearing capacity of the supports if the installation is carried out correctly. If even the smallestrules, the strength of the entire structure will be greatly reduced. Therefore, the installation process is best entrusted to a specialist who has extensive experience with these types of foundations.
Using a screw pile with a diameter of 133mm
At the time of the installation of a heavy structure on a screw foundation, the question often arises: what piles should be set in diameter and what should be their number? For massive structures, it is best to use elements with a large diameter. The bearing capacity of a screw pile of 133 mm with a blade diameter of 350 mm can withstand loads of 4 tons. With their help, you can install structures of any type - from a residential building to storage facilities.
Screw supports are quite often used in the construction of various piers and piers. For their device, piles with a pipe diameter of 133 mm are used. Among other things, they have a double protective coating against corrosion formations. Thanks to these characteristics, the base is firmly placed in areas with unstable soil. To find out the bearing capacity of the foundation, it is necessary to multiply the area and the soil resistance value.
An example of determining the number of piles per foundation
The calculation takes into account the structure of two floors on a foundation of 6 by 6 meters and the used timber material. On the construction site there is soil in the form of clay. The total weight of the building with all the nuances was 59 tons. The perimeter of the building is 24 meters, there are no internal partitions. First thingit is necessary to clarify the strength of the soil according to the table. In our case, this value will be equal to 6 kg per square centimeter. The load bearing factor is 1.75 (it is needed to provide a margin if necessary). The total area of the sole is calculated. Formula:
S=(PD) x (PD): 4=3.14 x 352: 4=961.6 centimeters. This is the definition of the diameter of the blades.
Formula for calculating non-optimized bearing capability:
F=S x Ro=961, 6 x 6=5770 kg.
Calculation of allowable weight per pile:
N=F: yk=5770: 1, 75=3279, which is approximately (rounded up) 3 tons 300 kilograms.
Determination of bearing characteristics
If screw piles are used in the construction of the foundation, the calculation of the bearing capacity is simply necessary. Many factors depend on this, including the service life of the entire building as a whole. In order to carry out calculation work, one should know the value of soil resistance, as well as the area of the blade, which is located at the ends of the screw support. But these values will not be enough, it is necessary to additionally calculate the number of supports that will be installed under the building.
To get a more accurate calculation, you should divide the carrier coefficient by the reliability indicator. All calculations and strength tests fit into the design documentation. In accordance with the drawn up plan of the building, the pre-calculated number of piles is evenly spaced around the perimeter of the entire foundation.
Calculation of screw base
The main factor, which, in turn, should be identified during the calculation period, is the overall level of load on all supports. The number of piles and the distance between them is determined by the diameter of the support pipe and the mass of the building. For example, the bearing capacity of 108 mm screw piles can withstand a weight of 3 tons. The load on the base includes the weight of the structure along with the influence of wind and snow accumulation.
The following factors affect the total weight of the structure:
- floor load;
- weight of bearing and secondary walls;
- roofing system;
- household items (furniture, appliances).
The load from the roof, walls, and ceilings must necessarily be calculated separately. For this, a table is used that indicates the weight of each type of material.
Area of use for piles with a diameter of 89 mm
The area in which support piles of medium diameter are most often used is the construction of small structures. This determines the bearing capacity of screw piles with a diameter of 89 mm in each case separately. The weight that can be distributed to each pile separately is 2 tons, no more. They can be used in the construction of such objects:
- medium-sized structures (bathhouse, cottage, garage, warehouse);
- supports for bases of arbors, greenhouses, cabins;
- metal gates and fences;
- berths and piers;
- supports for advertising banners.
If the choice falls on piles with such a diameter, then it is necessary to focus on certain factors, such as the scope of use and the composition of the soil. The reliability of the structure and its service life will directly depend on this.
Small Diameter Screw Mounts
Before choosing a pile, you need to decide what maximum load it should bear. For example, the bearing capacity of a screw pile 57 mm in diameter is the allowable fluctuation of the load on one support from 300 to 1000 kg. Due to such a minimum weight, the price of such elements is much lower than that of piles with a large diameter. It also reduces the cost of installing the foundation. This is due to the fact that a small screw support can be screwed in by hand, without the use of expensive construction equipment.
Installation of the foundation is carried out in just one day, which significantly reduces the time for the construction of the entire building as a whole. Another important advantage of these screw piles is the possibility of installation in any type of soil.
Piles with a diameter of 76 mm
The bearing capacity of screw piles of 76 millimeters in diameter can withstand a mass of one ton. In addition to being used in the construction of buildings of various weights, these piles can be used in repair work as an additional reinforcement.
The installation of piles with a diameter of 76 mm is equally possibleto carry out with one's own hand and using the construction mechanism. The cost of such a material is more expensive than that of elements with a smaller diameter, but the possibilities of application are much greater. Therefore, before purchasing the material, it is necessary to determine the requirements that will apply to the supports at the time of construction.
Determining the size of the base of a screw pile
When screw piles are screwed in, the soil is compacted. After installation, the pile support takes the entire load on itself. In order to determine the amount of load that a foundation consisting of screw supports can withstand, it is necessary to calculate the size of the sole area. Then, using the formula S=πR², the required indicator is fully calculated.
