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 structures have the ability to withstand heavy loads through the formation of friction. It can appear between screw pipes and soils. If there are dense layers of soil on the site, there is no point in additional installation of supports.
- Reference type - used in areas with solid soil for the construction of houses. They play the role of an intermediary in the transfer of load from home to the ground.
Before carrying out the installation of such a foundation, you should find out what bearing capacity of screw piles is required for construction.
Installation Nuances
In most cases, the bearing capacity of screw piles often depends on the size and diameter of the support. There are two ways to install a screw base:
- manual;
- using special equipment.
The bearing capacity does not depend on the type of installation. Both installation methods are carried out on 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 deteriorate the bearing capacity, in some situations, the installation of a screw pile is performed otherwise:
- Installation of a screw support in the soil, which has a solid structure, as well as in frozen soil. Mandatory drilling of small wells. This action will ensure that the screw support is safely screwed into the ground.
- If flooded soil prevails at the construction site, the surface of the screw piles must be additionally treated with an anti-corrosion agent. Concrete consistency must be poured into the body of the metal pipe. Due to this, the strength of the base material will increase, and its life will be extended.
If additional reinforcement is required, piles that have a length of more than 2 meters should be reinforced. Due to this, the bearing capacity of screw piles around the entire perimeter will increase.
It is important to know that the correct calculations of the bearing capacity of the supports can be made if the installation is carried out correctly. If even the slightest rules are violated, the strength of the entire structure will be much reduced. Therefore, the installation process is best entrusted to a specialist who has extensive experience working with these types of foundations.
Application of a screw pile with a diameter of 133 mm
At the time of installing a heavy structure on a screw foundation, the question often arises: what piles in diameter should be set and what should be their number? For massive structures, it is best to use elements with a large diameter. The bearing capacity of a 133 mm screw pile with a blade diameter of 350 mm can withstand loads weighing 4 tons. With their help, you can install structures of any type - from a residential building to storage facilities.
Screw supports are often used in the construction of a variety of moorings and piers. For their device, piles with a pipe diameter of 133 millimeters are used. Among other things, they have a double protective coating against corrosion. Due 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 size of the area and the value of soil resistance.
An example of determining the number of piles on a foundation
A two-story building on the foundation of 6 by 6 meters and the material of the timber used are taken into account. At the construction site is clay soil. The total weight of the building with all the nuances was 59 tons. The building is 24 meters along the perimeter, there are no internal partitions. First of all, it 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 coefficient of withstand load is 1.75 (it is needed to provide a stock if necessary). The calculation of the total area of ββthe sole. Formula:
S = (PD) x (PD): 4 = 3.14 x 352: 4 = 961.6 centimeters. This is the definition of the diameter of the blades.
The formula for calculating the non-optimized carrier capability is:
F = S x Ro = 961.6 x 6 = 5770 kg.
Calculation of allowable weight per pile:
N = F: yk = 5770: 1.75 = 3279, i.e. approximately (with rounding) 3 tons 300 kilograms.
Definition of the bearing characteristic
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 the calculation work, you should know the value of soil resistance, as well as the area of ββthe blade, which is located at the ends of the screw support. But these values ββare not 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 bearing coefficient by the reliability indicator. All calculations and strength tests fit into the design documentation. In accordance with the compiled plan of the structure, a pre-calculated number of piles is evenly placed around the perimeter of the entire foundation.
Calculation of the 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 base load includes the weight of the building along with the influence of wind and snow accumulation.
The following factors affect the total weight of a structure:
- floor load;
- weight of supporting and secondary walls;
- roofing system ;
- household items (furniture, appliances).
The load from the roof, walls, and also ceilings must be calculated separately. To do this, use the table in which the weight of each type of material is indicated.
Area of ββuse 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 of 89 mm diameter in each case separately. The weight that can be distributed on each pile individually is 2 tons, not more. They can be used in the construction of such objects:
- medium-sized buildings (bathhouse, cottage, garage, warehouse);
- supports for the bases of arbors, greenhouses, change houses;
- metal gates and fences;
- moorings 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 soil composition. The reliability of the structure and its life will directly depend on this.
Small diameter screw supports
Before making a choice of piles, it is necessary to determine what maximum load it must bear. For example, the bearing capacity of a screw pile 57 mm in diameter is the allowable load fluctuation on one support from 300 to 1000 kg. Due to this minimum weight, the price of such elements is much lower than that of piles with a large diameter. The cost of installing the foundation is also reduced . 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 erection of the entire building as a whole. Another important advantage of these screw piles is the ability to install 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 using various mass structures in construction, these piles can be used in repair work as an additional reinforcement.
The installation of piles with a diameter of 76 mm can equally be carried out with one's own hand and when using the construction mechanism. The cost of such a material is more expensive than that of elements with a smaller diameter, but there are much more possibilities for use. Therefore, before acquiring material, it is necessary to determine the requirements that will be imposed on the supports at the time of construction.
Determination of the size of the sole of a screw pile
When screw piles are screwed in, soil compaction occurs. After installation, the pile support fully accepts the entire load. 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 = ΟRΒ², a complete calculation of the required indicator is performed.