Soil loosening coefficient is an important parameter of construction work.

Construction work begins with a markup andexcavation for the foundation. Soil excavation occupies an important place in the construction cost estimates, and a significant amount of money is needed to pay for technologies that produce soil removal. To draw up a budget and estimate the cost, it is not enough to know only the size of the pit - it is also necessary to take into account the peculiarities of the soil. One of these characteristics is the rate of loosening of the soil, which allows to determine the increase in volume after the removal of the soil.

A good example of calculations

Whatever the construction work, they allmust begin with the layout (layout) of the site and the preparation of the foundation. In estimates that construction companies or the owner provide to the customer, earthworks always occupy the first place. The average consumer is confident that only the excavation of land and its removal are included in the assessment of the preparatory work. However, such work can not be done without taking into account the characteristics of the soil. An important characteristic is the coefficient of soil loosening (AWG). Want to figure out what exactly is in question and calculate the construction costs yourself? This is possible. Consider the question in more detail.

Why determine the coefficient of loosening of the soil?

Soil volumes before development and after excavationvary significantly. Calculations allow the contractor to understand how much soil will have to be removed. To estimate this part of the work, the following factors are taken into account: soil density, its moisture level and loosening.
In construction, soil types are conventionally divided into two main types:

• cemented;
• uncemented.

Первый вид называют еще скальным.These are mainly rocks (igneous, sedimentary, etc.). They are waterproof, with high density. For their development (separation) apply special explosion technology.
The second species is uncemented rocks.They are characterized by dispersion, easier to handle. Their density is much lower, so the development can be carried out manually, using special equipment (bulldozers, excavators). Sand, loam, clay, chernozem, mixed soil mixtures are referred to the uncemented form.

The most important factors determining the cost of preparatory earthworks

What should be considered when calculating? The complexity of the development and, accordingly, the cost of work depends on four indicators:

• humidity (water content in solids);
• density (mass of the cube of the soil before the start of development, in its natural state);
• adhesion (shear strength);
• loosening (ability to increase volumes during development).

Soil loosening coefficient - table (see below).

We take into account building codes

Ground moisture is fixed in percent. The norm is 6-24%. Accordingly, 5% and below - dry soils, and 25% and above - wet.
Knowing the performance of the clutch allows you to prevent the shift of the reservoir during work. The index of sandy loam usually does not exceed 3-50 kPa. For clays it is much higher and can reach 200 kPa.
Density is governed by the composition of the earth and its humidity. In the easiest categories there are sandy sands; in the densest - rocky soils, rocks.
Important: the data of the initial loosening is precisely proportional to the density: the heavier, denser and stronger the soil, the more space it will take after excavation, in the selected form.

KR on SNIP

Soil loosening coefficient according to SNIP:

• CR of loose sandy, wet sand or loam at a density of 1.5 is 1.15 (category one).
• KP dry unconsolidated sand at a density of 1.4 is 1.11 (category one).
• CR lightweight clay or very small gravel at a density of 1.75 is 1.25 (the third second).
• The CD of dense loam or ordinary clay at a density of 1.7 is 1.25 (category three).
• KR shale or heavy clay at a density of 1.9 is 1.35.

Density is left by default, t / m3.

Residual loosening

This indicator reflects the state of the compressedground. It is known that layers, loosened during the development of the site, over time, compressed. There is their compaction, sediment. The natural process accelerates the action of water (rain, artificial irrigation), high humidity, tamping mechanisms.
In this case, it is not necessary to calculate this indicator - it is already known and can be viewed in the table above.

Цифры, отражающие остаточное разрыхления, имеют value as in large (industrial), and private construction. They allow you to calculate the volumes of gravel that will go under the foundation. In addition, indicators are important for storing the selected soil or its disposal.

We calculate independently

Let's say you want to develop a plot. The task is to find out how much soil will be obtained after the preparatory work. The following data is known:

• trench width - 1.1 m;
• soil type - wet sand;
• the depth of the pit is 1.4 m.

Calculate the volume of the pit (Xk):
Xk = 41 * 1.1 * 1.4 = 64 m3.

Now we look at the initial loosening (soil loosening coefficient on wet sand) according to the table and count the volume that we will get after the works:
Xr = 64 * 1.2 = 77 m3

Thus, 77 cubes is the volume of the reservoir that is to be removed at the end of the work.