In the large territory of our planet in winter, minus temperatures are observed at which water freezes in the ground, to a depth determined by the cooling level. With a decrease in air temperature, the freezing rate increases. This factor is of great importance in construction, as it partially determines the level of laying the foundation of the house, as well as laying pipelines that transport water. There is a concept of the normative depth of soil freezing. This value depends on the geographical location of a particular territory. To determine this indicator, long-term observations were carried out, according to which the average values of the temperature regime were recorded. It should be noted that the definition of this indicator was carried out in the absence of snow cover.
In practice, the real value of the parameter and the normative value indicated in the normative-technical literature differ from each other.
How does the soil freeze through
During the construction of a heated residential building, the estimated depth of frost penetration will be less than the standard depth of approximately 10 to 30%, depending on the type of floor.
Irregularity of freezing
After the above information, you can think about whether snow removal is beneficial or detrimental. On the one hand, this event will relieve the cleaned area from flooding during the thaw, on the other hand, the cleared areas will become bare, which means they will be more susceptible to penetration into the ground below-zero temperature. The presence of snow in this case is a useful phenomenon. In order not to be blown away from certain territories, it is possible to plant shrubs on the site that prevent soil from being exposed in frosty weather.
In different territories located in different zones, seasonal freezing of the soil is determined according to SNiP 2. 02. 01-83 *. Experts have been observing for many years and determined the average values of this parameter. According to clause 2. 27, the depth of soil freezing can be calculated using the formula:
dfn = do ∙ mt, where
do is a coefficient depending on the type of soil.
With clay and loam, do = 0.23, sandy loam and fine sand - 0.28, gravel sand and grain size above the average - 0.30, coarse-grained soil - 0.34.
mt is a coefficient that is determined by summing up the highest monthly average values of sub-zero temperatures during the winter period for a specific area. To determine it, you need to use the table 3 SNiPa 23-01-99 *.
From the formula it is clear that the type of soil affects the mark of soil freezing. For each of them is taken its own individual coefficient. If the depth of soil overcooling exceeds the level of groundwater, this fact must be taken into account during construction. Water in freezing weather will freeze, increase in volume and put pressure on the soil. Under the influence of ice, the soil will move and act destructively on the foundation. For this reason, the main house must be built below the depth of freezing.
For example, the seasonal depth of soil freezing in the Leningrad region is 1.20 m in the Moscow region - 1.40 m.