Opera of river water is called river water, which in winter due to local freezing of ice to the bottom follows pressure on the surface of the ice and forms new powerful strata of the last. Ice height is an indicator of the pressure of water forming ice.
In addition to river valleys, ice is often formed in places removed from rivers (pound ice).
In winter, with severe freezing of the soil in certain places, its slow swelling and the formation of tubercles begin, inside of which there is ice or ice with water; Bugrs over time increase and nyavrrh or side form, from which soil water flows, which gives new layers of ice on the surface of the tubercles. In the spring and summer, after the ice of ice, ice tubers disappear. The height of these tubercles reaches 5, and the thickness of the ice above them over 3 m these ice forms ice fields of small width and significant length (up to several hundred meters), often fill up the structures standing in their way, are transplanted through the railway canvas with small embankments and score holes of artificial structures and underground buildings.
When thawing the thicknesses of permafrost, as well as soil ice, elevated dry areas are often omitted, the resulting cavities are filled with water and form lakes and wet lowlands. The very relief of the terrain in the field of permafrost is changeable, since the melting of centuries -old stocks of ice lowers large areas or, on the contrary, with the formation of soil ice and tubercles, sometimes bloating of the upper layers to a height of several tens of meters.
In the thickness of the forever perzed layer, water is in a solid state in the form of ice layers with a thickness of a millimeter to tens of meters.
The distinctive properties of frozen soils compared to the Talys are their staining or deposition in them, which prevents the natural circulation of water, although pebble sediments are also found that are frozen to a considerable depth, in peat bogs there is a multi -layer permafrost on the outskirts of the valleys, consisting of interspersed peat and ice. Then there is the so -called dry permafrost in clay, sandy and indigenous rocks, where it is difficult to catch from ordinary melt soils.
Eternal permafrost while maintaining the temperature below zero is distinguished by good building qualities. Resistance to compression of frozen soils depends on the type of soils, temperature and degree of humidity.
Temporary resistance to compression of eternal-freezed soils at negative temperatures close to zero is accepted according to the following table:
When determining the permissible stresses for forever frozen soils, the security coefficient is taken (provided that the permafrost regime is preserved) from 6 to 4, depending on the class of the structure, which gives values from 3 to 15 kg for permissible loads.
