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Soil compaction factor (values)

Soil compaction factor — the ratio of the actual density of the soil (soil skeleton) in the embankment, to the maximum density of the soil (soil skeleton).


What does soil compaction factor 95 % mean?

Soil compaction factor of 95% means that the actual density of the soil is 95% of the maximum possible density of the soil (soil determined in the laboratory).

This coefficient is determined by the following methods:

1. Cutting ring method — soil samples are taken from the compacted layer and tested in a soil laboratory in accordance with GOST 5180-2015 «Soils. Methods of laboratory determination of physical characteristics». The main disadvantage of the method: lengthy tests (transportation and laboratory testing) [Russian standard]

2. Dynamic soil densitometer (DPG) — the principle of operation is based on the falling load method, in which the impact force and soil deformation are measured. It is used in conjunction with the cutting ring method to accelerate the determination of soil compaction coefficient.

At the initial stage, the DPG is calibrated at several sampling sites according to test data by the cutting ring method (GOST 5180-2015) [Russian standard]

Then, according to the calibration data, the compaction coefficient is determined at the remaining points, which allows to obtain results immediately on the site.

The required soil compaction factor (according to SNiP 3.02.01-87) for backfill or embankment is presented in table 1.

Table 1. Soil compaction factor

Soil type Soil compaction factors kcom, %
under load on the surface of compacted soil, MPa (kg / cm2)
0 0,05 – 0,2 (0,5 – 2) св. 0,2 (2)
with the total thickness of bulk soil, m
до 2 2,01-4 4,01-6 св. 6 до 2 2,01-4 4,01-6 св. 6 до 2 2,01-4 4,01-6 св. 6
Clay 92 93 94 95 94 95 96 97 95 96 97 98
Sand 91 92 93 94 93 94 95 96 94 95 96 97







For example, the value of the compaction coefficient of the backfill soil made of sand, the filling capacity of 2.5 m and the load on the embankment of 0.3 MPa is 95 %