It has long been no secret that the correct choice of the foundation for the house and the quality of construction determine the service life and convenience of life in it. Calculation of screw piles for the foundation is necessary even at the stage of project development, since without this information it is not possible to prepare an estimate, purchase tools and materials.
Design features
Due to their versatility, metal screw piles for the foundation have earned widespread use among developers.
What are the features of piles?
- Design. This is a welded pipe with a sharp end, on which blades in the form of a screw are welded - a fixing element that does not allow the pile to move from its seat when the soil swells, stably holding the entire structure.
- Mounting. Installation is carried out with a clear control of the verticality of the pipe, made mechanically or manually. The main requirement is that drilling takes place to a stable soil layer. Piling is carried out regardless of the season and precipitation.
Indicators affecting the calculation
Calculation of screw piles for the foundation will require determining the total load on the base of the house, which consists of:
- The mass of the building to be installed on the foundation. When designing a house, mass is a calculated indicator, it is determined by the materials embedded in the design.
- Extra load, including snow, furniture, equipment and people. Information for calculating the loads on the foundation must be taken from the approved regulatory documents SNIP No. 2.01.07-85. The payload in the form of people and furniture is taken on average 150 kg per m 2 .
- Soil density. To determine, it is necessary to carry out engineering and geodetic studies, since without these works the object will not pass state examination. The calculation is carried out in accordance with SNIP No. 2.02.03-85.
For private construction of houses up to 3 floors, research can be done on their own.
After performing the calculation of the rated loads, it is necessary to take into account a safety factor of 1.2.
Types of piles
It is impossible to calculate the foundation of screw piles for a house without first choosing their type. Each size is calculated for a certain type of facility being built.
The dependence of the diameter of the pile on the type of loadPipe diameter mm | Load, t | Appointment |
57 | up to 1 | Under the supporting posts of various types of fencing. |
76 | until 3 | For light country houses. |
86 | 3 ÷ 4 | Heavy fences, single-storey frame houses, gazebos, verandas. |
108 | to 10 | Buildings on 2 floors of frame type, as well as wooden buildings made of timber. |
133 | 9 ÷ 14 | Under the house of moderate severity of foam blocks. |
219 | 10 | For heavy brick structures and two-, three-story houses. |
325 | More than 10 | Rarely used for residential buildings, more for industrial facilities. |
The choice of length depends on:
- Horizontal construction site: if there are significant differences in height, then it is possible to choose piles of various lengths.
- The nature of the soil. A reliable installation involves screwing to a stable soil and below the level of soil freezing by 25 ÷ 40 cm. In this case, the pile part should go into the soil no higher than 1500 mm.
Length standardized:
- Short: 1.65 ÷ 2.5 m.
- Long: up to 11.5 m (pitch 500 mm).
Calculation of the number of screw piles for the foundation: stages
You will need:
- The plan of the plot on the scale on which it is necessary to apply the planned base with center lines.
- Bind to communication lines: sewer pipe from plumbing rooms and from the kitchen, with a drawing of the diameters.
- Results of engineering and geological research.
Location:
- Single - point supports for light constructions or country houses.
- A tape is a sequential arrangement with a specific step.
- Scrub - for heavy houses with many partitions and under each support in a frame structure.
The calculation of screw piles for the foundation is carried out taking into account the features of the layout:
- The distance between the fulcrum must be at least 2500 mm.
- The pile should be installed in places of peak loads, which are concentrated in the center of intersection of perpendicular lines, namely:
- In the corners of the building.
- At the joints of load-bearing walls and partitions.
- Intermediate supports should be installed evenly, including along the diagonals of the main cells of the building.
- The size of piles and blades is determined depending on the type of load and soil characteristics.
The effect of soil on the calculation
Whatever screw piles are chosen for the foundation, the calculation of the load is impossible without determining the bearing capacity of the soil. So, the soil does not always have the necessary composition, which allows the building to withstand without subsidence.
Important! The selected pile should not exceed the value of the withstand load of the soil.
To determine the bearing capacity of soils , the soil composition is first determined, and then compared with the characteristics given in the table.
The load kg / m 2 carried by different types of soilType of soil | View | Ground resistance kg / cm 2 for a pile lowered to 2 m (SNIP 2.02.03-85) |
Average | Dense |
Sand | Large | 12 | thirteen |
Average | eleven | 12 |
Shallow, wet | 4 | 5 |
Shallow, wet | 2 | 3 |
Sandy loam | Dry | 4 | 5 |
Wet | 2 | 3 |
Loam | Dry | 3 | 4 |
Wet | 1 | 3 |
Clay | Dry | 2,5 | 6 |
Wet | 1 | 4 |
In order to calculate the screw piles for the foundation, it is necessary to determine the type of soil:
- Coarse sand: 2.5–5 mm one grain of sand, up to 2 mm - medium. Does not change its size.
- Sandy loam is obtained by mixing sandy clay with a small percentage (10%) of clay.
- If the clay content is up to 30%, loam will be obtained. When wet, the mixture does not spread, but can be rolled into a ball, but when pressed, cracks appear.
- If the lump of moist soil does not crack under pressure, but is crushed plastic, the clay composition is above 30%.
Note! The higher the clay content, the higher the swelling of the soil.
- Peat - soft and airy composition does not imply bearing loads.
The proximity of groundwater and the degree of moisture resistance is determined by drilling a well to a depth of lowering piles. If water has formed in a standing hole, then there is a moisture-saturated soil with a close location of the aquifer.
Screw piles for the foundation: customer reviews
Pile reviews depend on where the buyer purchased the product, as many complain about poor manufacture, including poor anti-corrosion treatment. In most cases, home owners praise the construction on complex water-saturated soils, since a pile for such an area is the cheapest and most reliable type of foundation. Also, do not forget about the speed and high quality of installation of such buildings in any weather, it is this plus that many developers note.
Total
Whether or not to use the pile as the basis for the construction depends largely on the terrain and installation conditions. Knowledge of calculation rules and data sources is desirable even in cases where the calculation is performed by a construction company.