soil Structure
The Mechanical structure of soil is also a determinative at a choice of a site for building construction, the organisation of vacation spots of people (parks, squares) etc.
Air filling a time of soil, has the big hygienic value as all oxidising processes with participation of aerobic bacteria are possible only in the presence of oxygen enough. Between soil and atmospheric air there is the constant exchange caused by a difference of temperature and atmospheric pressure.
Soil air essentially differs from the atmospheric. Its structure depends on gas exchange with atmospheric air and from biological processes proceeding in soil. So, the more in soil of organic substances, the more oxygen goes on their oxidation. Therefore in process of deepening in soil the oxygen maintenance in it decreases to 10% and more low. Accordingly quantity РЎ0 2 increases to 15% and more. In soil there can be a hydrogen sulphide, ammonia, flying hydrocarbons and other gases. Such soil air can be allocated from soil and arrive in prizemnyj a layer of atmosphere as a result of decrease in atmospheric pressure, increase of level of standing of subsoil waters, differences of temperatures of soil and atmospheric air.
Soil air can be replaced with the water which source is an atmospheric precipitation. Soil water causes water penetration, a moisture capacity and hygroscopicity of soil.
Water penetration is an ability of soil to pass water. Various kinds of soil differently pass water. So, fine-grained soil, in which particles densely adjoin to each other, possesses small, and coarse-grained - the big water penetration. This property of soil consider at a choice of the ground area for building, at the device of fields of an irrigation etc.
The Moisture capacity is an ability of soil to keep water in the time. A good moisture capacity the clay soil possesses. It can be impregnated by water on 60-70%, while coarse-grained sandy soil - on 15-20%. The greatest moisture capacity the peat soil possesses.
Hygroscopicity is an ability of soil water to rise upwards on a soil time. Hygroscopicity of soil that more than is less size of soil particles. In clay soil soil water can rise on a time on 3-4 m. the Capillary raising of soil water s it is necessary to consider at a bookmark of the bases of buildings as it can become the reason of dampness of walls. For municipal and housing construction it is necessary to choose territory with the pure coarse-grained soil possessing big vozduho - both water penetration and a small moisture capacity.
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