Foundations of buildings and structures-parts of buildings and structures (mainly underground), which serve to transfer loads from buildings (structures) on a natural or artificial basis.
The cost of the Foundation is about 15-20% of the cost of the house. Correction of improperly executed Foundation is difficult to do and the cost of these works can reach 50% of the value of the house, if the house itself is not significantly damaged. Therefore, the choice of Foundation should be approached very responsibly. Skewed porch, veranda, poorly opening doors and Windows in wooden houses, as well as cracks in the walls of brick houses - all the result of improper choice of Foundation.
Types of foundations
The foundations are made of concrete or of concrete combined with brick walls or walls of stone.
According to the method of resting on the ground foundations are divided into tape, columnar (pile) and plate.
Columnar or pile foundations - the most common and cheap type of foundations for buildings with light walls. The construction of such foundations is 1.5-2 times cheaper than tape. The main element of such foundations is a pillar (pile). The column can be wooden, stone, brick, concrete and reinforced concrete. It can also be an asbestos pipe used as a mold and filled with concrete mix.
Strip foundations are foundations that have the same cross-sectional shape around the perimeter of the walls of the building (including under all of its internal load-bearing walls). These foundations erecting heavy buildings. In heaving and deeply freezing soils are rarely used.
Slab foundations are constructed on heavy heaving and subsidence soils. They have a rigid structure - one plate, made under the entire plane of the building. Such foundations are well aligned all vertical and horizontal movement of the soil, they received another name - floating. The construction of slab foundations is practiced mainly in low-rise construction with a small and simple form of the building plan. Slab foundations are quite expensive because of the large volume of concrete and metal consumption for reinforcement.
Shallow foundations are classified into the belt under the load-bearing and self-bearing walls; the tape under a row of columns; columnar to the walls; under a separate column, and in combination with Foundation beams and the walls; a solid with flat or ribbed slabs (under an entire structure or part of it); massive (all under construction). Such foundations are usually is step-shaped, with widening downwards. The top surface of the base separating it from overlying part of the building (construction), is called a sawn - off shotgun, and the bottom relying on a ground of the basis, - a sole. The distance from the sawn-off to the sole is called the height of the Foundation, the distance from the planning mark of the earth's surface to the sole-the depth of the Foundation. In the individual foundations in their upper part (called podkolonnik) arranged recess (Cup) for installation.
Select the type of Foundation depends on the geotechnical and hydrogeological conditions of building, purpose and design features of a building or structure, the load transmitted to the Foundation, as well as manufacturing capabilities of construction organizations. The depth of the Foundation of buildings and structures is set depending on the properties and nature of the layers of soil, groundwater level (taking into account its fluctuations in the process of construction and operation of facilities), the magnitude and nature of the loads acting on the base, the depth of underground utilities and foundations for machinery and equipment, climatic features of the construction area (depth of seasonal freezing, etc.). The accepted depth of laying of the base shall be sufficient for ensuring stability of the basis and an exception of possibility of heaving of soil (at its freezing) and precipitation (at thawing). In non-porous soils, when the groundwater level occurs at a considerable distance from the ground surface, it is allowed to lay the sole of the Foundation above the depth of soil freezing. The dimensions of the Foundation base is determined proceeding from the condition that the average pressure on the base does not exceed the design pressure, the value of which depends on the type and properties of soil, depth of Foundation, the design features of the building. When assigning the size of the base of the Foundation take into account the limit values of the vertical deformations (precipitation, hoists), which still provided the necessary strength advancement structures and compliance with building (construction) technological or architectural requirements. Under the action of significant horizontal loads (incl. seismic), as well as in the case of water-saturated clay and frozen soils must be provided, in addition, the stability of the base.
Calculation of the construction of the Foundation of buildings and structures is made by strength and the magnitude of crack opening. Shallow foundations are usually arranged solid - stone materials, rubble concrete, concrete and reinforced concrete. Tape, separate (under columns), continuous and massive bases, as a rule, are executed from reinforced concrete. Materials used for the Foundation of buildings and structures must have the necessary water and frost resistance. In the present construction is highly efficient prefabricated strip foundations under walls of buildings, performed from the standard concrete blocks-concrete seat and the stem blocks or panels. Pillow blocks can be laid with a break, forming an intermittent Foundation. The sediment of the latter is less than the tape, so the pressure under its sole can be increased by 20-30%. Prefabricated foundations for individual columns and pillars are arranged from blocks of glass type or from several blocks-pillows.
The foundations of buildings with basements at a high level of groundwater should have waterproofing, excluding the possibility of flooding of basements. To protect the Foundation of buildings and structures from the action of aggressive groundwater use dense concrete with special additives, as well as coating, gluing and other types of waterproofing.
Shallow foundations are usually built in pits or trenches. Gets the propagation method wyrmbane pits (under separate bases) or trenches (below the strip Foundation) with the help of ramming machines. In this case, earthworks are excluded and additional compaction of the base soil is provided.
This building is designed precast strip Foundation, due to the fact that not far from the construction site is a plant of concrete products.