Peat is a biogenic soil with a porous structure, the bearing capacity of which is of very little importance. When building a house, this very fact often becomes a huge problem, since it is not uncommon in Russia. Indeed, after construction, the house will shrink for several more years. Since peat is compressed under load, the house can go into the ground up to half a meter. Therefore, builders do not recommend building on peat soils.
However, what if there is an area where peat is found? Do not sell the same. [contents ]
Do not despair, there are several ways to build a foundation on peat soil.
So what kind of foundation can be built on peat soil?
In order to determine the method, it is first necessary to conduct geological surveys to determine the depth of the peat with the involvement of professionals, but it will not be cheap.
You can do it and dig a small pit 0.5x0.5 meters around the perimeter and 2 meters in depth. If it turns out that the peat layer is small, then the most convenient way will be the peat method. If the peat layer is large, then the method with a pile foundation is more suitable.
Excavation and replacement of soil is most often done using an excavator.
The peat layer is removed. At the same time, a foundation pit is immediately dug, the bottom of which is covered with gravel and sand, and a pillow is made to increase the bearing capacity of the foundation. In such a pit, it is convenient to make at least a strip, even a tiled foundation.
This is the simplest and easiest way to erect a foundation on peat soil, however, its use is limited to a thickness of the peat layer no more than 2m.
In Russia, soils with a layer of peat of 3 m and more often prevail. In such cases, a pile-type foundation is used.
The construction of the pile foundation begins with marking the site. With the help of pegs, they mark the places where in the future wells will be drilled for piles. The distance between the piles, as a rule, is 2-2.
5 meters, which makes it possible to have a foundation with a high bearing capacity.
Depressions of 30-40 centimeters are made in the marking places. This is done in order to remove the top layer of vegetation with grass and roots to facilitate the work of the drill. You can drill wells with a gas drill, electric drill, you can also hire an auto-drilling unit, or you can drill manually.
It is advisable to use a drill that can expand the base of the piles.
The drilling depth should be such that the piles pass through the peat layer and rest on a dense soil layer.
Next, the piles are waterproofed. Most often, roofing material is used for this. Roofing material is rolled up into a pipe of several layers with a diameter equal to the diameter of the well. The seams are glued with tape.
The resulting structure is lowered into the well. In addition to waterproofing, it will also play the role of formwork, preventing concrete from flowing into the ground.
To strengthen the piles and give them flexibility, with horizontal displacements of soils, the piles are reinforced. Reinforcement is made with reinforcement with a diameter of 6-8 mm. 4 rods are interconnected by crossbars in the form of squares with a distance of 20 centimeters, a frame is made.
The connection is made by knitting with annealed wire. The frame is lowered to the entire depth of the well, 20-30 centimeters are left above the surface for connection with the grillage.
For the preparation of concrete for pouring piles, cement of a grade not lower than M400 is used. Only river sand is allowed. Crushed stone is used in various fractions with a corrugated surface.
Proportions: for one part of cement, three parts of sand and two parts of crushed stone. The solution should be not too liquid and moderately thick.
After the concrete is ready, it is fed in small portions into the well. It should be 40-50 centimeters each, after which tamping is necessary. You can ram both manually and with the help of vibrating machines.
The process of concreting one pile should take place without stopping, the seized and fresh concrete will form an artificial crack, and the pile will no longer be monolithic, which will significantly worsen its bearing capacity.
After pouring all the piles, it is necessary to connect them into a single structure. To do this, create a grillage.
The grillage is made either shallowly buried or not buried.
The construction of a shallow grillage begins with the preparation of a trench that runs along the entire perimeter of the house, capturing all the pile deflectors.
In the dug trench, a so-called sand pillow is made: sand is poured at the bottom of the trench about fifteen centimeters and carefully tamped from above. They also cover it with rubble about fifteen centimeters. In this case, the pile heads should be higher than the dumping.
Next, waterproofing is performed. Roofing material is laid on the crushed stone dump and the formwork is mounted.
The formwork must be properly secured to avoid extrusion by concrete. Then the grillage is reinforced. The reinforcement frame of the grillage must be connected to the pile heads.
After completing all the stages, the grillage is poured with concrete. It is allowed to use cement grade M300 for the grillage, all other proportions are taken the same as for pouring piles.
The construction of an unburied grillage is the same, except for the preparation of the trench. It is poured directly over the soil surface.
After pouring concrete, it is necessary for the concrete to gain strength, this directly depends on the ambient temperature.
On average, at a temperature of +20 degrees Celsius and M300 concrete grade, it will gain strength 100% in 28 days.
Also, for peat soils, a pile-screw foundation is used.
With the use of screw piles, which must be screwed in 1 meter before screwing into a solid base. Subsequently, the entire structure must be connected to each other using corners or square pipes.
In conclusion: construction on peat soil is difficult, it is not the most suitable soil for construction, and, nevertheless, with careful preparation and adherence to all the subtleties, the task is quite feasible.
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