All existing buildings and structures are built on soil, which must have such qualities as strength and sufficient bearing capacity. But the land intended for building does not always have such qualities. Usually, its qualities are deteriorated by groundwater that forms in the ground during and after precipitation. In addition, in winter the soil, as a rule, freezes unevenly, and this threatens it with swelling and uneven rise. Such soil mechanics leads to destructive consequences for the foundation and the entire structure as a whole.
To prevent this, before laying the foundation, you need to correctly determine the types of soil, on what construction is to be , the depth of possible freezing and the level at which groundwater accumulates, as well as the type of future construction.
They are called soil rather conditionally, since they are a solid stone that is not influenced by precipitation, freezing, and does not change its properties in normal climatic conditions. It could be called the ideal foundation for the foundation, if not for the complexity of the development of the site on it. This type of soil is the most reliable and the foundation can be installed on it without additional openings and deepenings.
Cartilaginous soil is quite reliable for construction. It is not subject to swelling and erosion. Gristly soils are a mixture of clay, sand, stone debris, rubble and gravel. They are poorly washed out by water, are not subject to swelling and are quite reliable. On such soil, even a not very deep strip foundation can withstand large structures.
Experts do not recommend laying a foundation on such a soil to a depth of less than 50 cm.
Sandy soils are slightly freezing and do not accumulate water. They are perfectly compacted and compacted, but they can sag under heavy load, so the optimum depth of the foundation on such soil is up to 70 cm. The larger particles the sand contains, the more load it can withstand. Dusty sand is classified separately, on which the foundation needs even greater strengthening.
Clay soils, loam and sandy loam - the most complex type of soil, consisting of sand and clay particles. Sandy loam is about 10% clay, and loam is 30%. They erode, liquefy and sink, deeply freeze and swell in the cold. The foundation on clay soil must be laid to the full depth of freezing. In winter, they can freeze to a depth of one and a half meters.
Peat soils, which are drained bogs, are usually highly saturated with moisture. They are very likely to have groundwater.Before laying the foundation in such a place, it is necessary to drain the soil or lay drainage channels, or tamp and strengthen the soil by laying a layer consisting of sand, cement and bitumen.
The depth of soil freezing directly depends on its type. Rocky soils, for example, do not contain water at all, their linear dimensions and characteristics change slightly.
The temperature coefficient of linear expansion of granite is 0.000008 per 1 degree. Compared to this, ice expands and contracts 6 times more, and water 100 times. Accordingly, illiterate construction on freezing, heaving and water-filled soils can lead to the ejection of the foundation from the ground, and its rupture.
The type of building also plays an important role in the choice of the type of foundation.
Therefore, it is necessary to determine not only the type of soil, but also the size of the structure, and its load on the base, because the load on the foundation of a light frame one-story house and a heavy two-story brick house is undoubtedly different. The type of foundation is also influenced by whether the developer wants to build a house with a basement, cellar or basement.
Ideally, the laying of any foundation should be done so that its lowest point is below the freezing depth. The soil qualities at this depth are usually stable and predictable.
There are a lot of types of foundations now.
The most common in the construction of summer cottages and country houses are shallow strip foundations and columnar with bandaging. The most popular materials at the present time are rubble concrete, brick and reinforced concrete.
Rubbish concrete is a mixture of cement-sand mortar and large stones. The solution in this case serves as a glue that fills the space between the stones, which eliminates their displacement. The foundation is very reliable and is used on light sandy and rocky soils.
In clayey terrain, such a foundation can rupture or crack.
Reinforced concrete consists of a mixture of cement, sand and gravel ... It is reinforced with mesh or reinforcement rods, which depends on the direction of the pressure of the frozen soil.
This is the most common foundation material. Its advantages include low cost, strength, and the fact that complex monolithic configurations can be created on it. When laying such foundations with the use of concrete vibrators, foundations with good bearing capacity, reliable and strong, suitable for any soil are obtained.
Brick is used exclusively for aboveground parts of the foundation and basement parts. It is categorically impossible to lay a brick below the surface of the ground, because it is very hygroscopic and can collapse in frost.
Silicate brick simply decomposes in the ground in several decades.
These are rectangular or round pit, filled with rubble concrete or reinforced vertically with rods and poured with concrete at ground level. Above, the column is brought out using bricks and cast immediately to the desired height. Usually the posts are located at a distance of 1 - 1.5 - 2 meters over the entire area of the building.
It is possible to use split, removable and fixed formwork.
Nowadays, the device of a columnar foundation using TISE technology has become popular. It consists in the fact that a drill is made with a depth of 1.5 - 2 meters, which expands conically at the bottom, is reinforced and poured with concrete. The essence of technology is precisely this internal expansion.
The advantages of the columnar foundation are its cheapness, reliability, no additional costs for waterproofing, installation of blind areas , finishing the basement. But it is only used for the construction of frame or wooden houses. The presence of a cellar, basement, basement with it is excluded. Such a foundation is laid on soils that are not subject to swelling. Since the columns are connected to each other only by the lags lying on them, with the mobility of the soil, they can change their location and slope.
Avoid problems with the mobility of the columns. The second name of the dressing is randbalk. Randbalka significantly improves the quality of the foundation and allows you to build even brick buildings with not very thick walls on it. But the dressing device makes the foundation more expensive and complex, since it requires a single reinforcement in both the beam and the post. The rundown is usually located either above the surface of the ground, or with a slight deepening, on a pad of sand.
Represents a single reinforced concrete structure, brought out to the ground level or slightly higher and a brick superstructure above it. The depth of the tape is about 50-70 cm. A sand cushion is made under it, with a depth of 20-30 cm. With such a foundation, it is already possible to use concrete hollow-core slabs as ceilings and erect any low-rise building. With decent moisture insulation, it is possible to equip the cellar in the foundation structure.
It will be very useful for the construction of such a foundation to arrange pits located with a frequency of 1.5 - 2 meters by drilling them with a drill. The depth of their occurrence must be located below the freezing depth.
This is the most common type of foundation among developers.
Is the most reliable foundation.
It differs from the previous one in that the entire foundation tape lies at a level below the freezing of the soil.Such a device guarantees the stability of the structure on almost all soils. Again, this is the only kind of foundation that a developer can equip a basement with.
Practically the only type of foundation for the construction of a heavy monolithic structure on soils with a high content of clay and peat and a high probability of swelling. Its device practically does not require any work below ground level, except for filling a 20-30 cm sand pillow.
On it there is a monolithic slab suitable for the size of the house. The house seems to "float" on this foundation and the type of soil has little effect on it.
Such a foundation is not expensive at all, precisely due to the fact that earthworks are excluded. The only limitation is that the site should not be on a slope, because the pillow will begin to creep sooner or later.
In cases where a basement is needed, a foundation pit is dug to the required depth.
At the bottom there is a cushion of sand and gravel and a monolithic slab is cast on it. The basement walls are erected on it. From the outside, they must be waterproofed. After that, the void between the walls of the basement and the pit is filled up, and a clay hydraulic lock is made. This method is the most expensive, as it requires a lot of all types of work.
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