RU2487336C2 - Method to detect air content in thawed soil - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: after taking a soil sample, weighing and detection of its volume, moisture, the soil sample is additionally dried. Then the volume of solid soil particles is determined, as well as density of dry soil, density of solid particles. Afterwards the relative air content is determined in thawed soil, besides, calculation of air content in thawed soil is carried out according to the formula $$\frac{Va}{V}=1-{\rho }_d\left(\frac{1}{{\rho }_s}+\frac{w}{{\rho }_w}\right),$$

where V_a - volume of air in the thawed soil sample; V - sample volume; $${\rho }_d=\frac{m_d}{V},$$

density of dry soil, where m_d - mass of dry soil sample; density of solid particles $${\rho }_s=\frac{m_d}{V_d},$$

where V_d - volume of solid particles of the sample - soil moisture $$w=\frac{m-m_d}{m_d},$$

where m - mass of soil sample; ρ_w - water density.

EFFECT: expanded area of application due to possibility of accurate measurement of air content and accordingly specification of assessment of deformation properties of soil.

Description

The invention relates to the field of engineering geology, in particular to the determination of the physical properties of soils.

The well-known "Method for determining bulk density, specific gravity, porosity and trapped air in soils and soils and a pycnometer for its implementation" (SU 125938) [1]. The measured volume of liquid filling macropores and micropores of the soil is introduced into the pycnometer, and after two to three minutes, the liquid that has not absorbed into the soil is drained, then the pycnometer is re-filled with liquid to the risks, placed under vacuum to pump out trapped air and again measure the volume of liquid, additionally introduced before the risks on the pycnometer.

The disadvantage of this method is the reduced measurement accuracy associated with the use of liquid (kerosene), the nature of the interaction of which is individual for each soil composition.

Closest to the claimed technical solution is "METHOD FOR DETERMINING THE PHYSICAL PROPERTIES OF FROZEN SOIL AND A DEVICE FOR ITS IMPLEMENTATION" RU 2193180 [2], which includes sampling the soil, weighing and determining its volume and humidity.

The disadvantage of this method [2] is the narrow scope associated with the inability to accurately determine the air content in the soil, which leads to a decrease in the accuracy of the assessment of the deformation characteristics of soils of primary importance for construction.

The technical result of the invention is the expansion of the scope by providing the ability to accurately measure the air content and, as a result, refinement of the assessment of the deformation properties of soils.

The technical result is achieved by the fact that after sampling the soil, weighing and determining its volume, moisture, the soil sample is additionally dried, the volume of solid particles of the soil, the density of dry soil, the density of solid particles are determined, and then the relative air content in the thawed soil is determined, and the calculation the air content in the thawed soil is performed according to the formula

$$\frac{V_a}{V}=\mathrm{one}-{\rho }_d\left(\frac{\mathrm{one}}{{\rho }_s}+\frac{w}{{\rho }_w}\right)$$

where V _a is the volume of air in the sample of thawed soil;

V is the volume of the sample;

- плотность сухого грунта, $${\rho }_d=\frac{m_d}{V}$$

- density of dry soil,

where m _d is the mass of a dry soil sample;

- плотность твердых частиц, $${\rho }_s=\frac{m_d}{V_d}$$

- density of solid particles,

where V _d is the volume of solid particles of the sample;

- влажность грунта, $$w=\frac{m-m_d}{m_d}$$

- soil moisture,

where m is the mass of the soil sample;

ρ _w is the density of water.

Parameters determined by known methods:

- soil density

$$\rho =\frac{m}{V},\left(\mathrm{one}\right)$$

where m is the mass of the soil sample; V is the volume of the sample;

- density of dry soil

$${\rho }_d=\frac{m_d}{V},\left(2\right)$$

where m _d is the mass of a dry soil sample;

- density of solid particles

$${\rho }_s=\frac{m_d}{V_d},\left(3\right)$$

where V _d is the volume of solid particles of the sample;

- soil moisture

$$w=\frac{m-m_d}{m_d}.\left(\mathrm{four}\right)$$

The final dependence of the ratio of the volume of air in the soil to the total volume of the soil is:

$$\frac{V_a}{V}=\mathrm{one}-{\rho }_d\left(\frac{\mathrm{one}}{{\rho }_s}+\frac{w}{{\rho }_w}\right),\left(5\right)$$

Dependence (5) is obtained from the representation of the volume of soil as the sum of the volumes of its components.

$$V=V_d+V_w+V_a,\left(6\right)$$

where V _w and V _a are the volume of water and air in the soil, respectively.

From the expressions (2) and (3) it follows that

$$V_d=\frac{{\rho }_d}{{\rho }_s}V.\left(7\right)$$

The volume of water in the ground is

$$V_w=\frac{m_w}{{\rho }_w},\left(8\right)$$

where m _w = mm _d is the mass of water in the soil.

The mass of water in the soil on the basis of (4) can be represented as

$$m-m_d=m_{d}w\left(9\right)$$

or subject to (2)

$$m-m_d=w{\rho }_{d}V.\left(10\right)$$

After substituting the expression for the mass of water (10) in (8), we obtain

$$V_w=\frac{w{\rho }_{d}V}{{\rho }_w}.\left(\mathrm{eleven}\right)$$

Substituting (7) and (11) into (6), after a small conversion, we find the expression of the relative air content in the thawed soil

$$\frac{V_a}{V}=\mathrm{one}-{\rho }_d\left(\frac{\mathrm{one}}{{\rho }_s}+\frac{w}{{\rho }_w}\right).\left(12\right)$$

An example of calculating the air content in thawed soil.

According to experimentally found indicators of the physical properties of thawed soil, as well as water:

w = 0.20 CU, ρ _d = 1,667 g / cm ³ , ρ _s = 2,70 g / cm ³ , ρ _w = 1,0 g / cm ³ and ρ _i = 0,916 g / cm ³

by the formula (12) we find

. $$\frac{V_a}{V}=\mathrm{one}-\mathrm{1,667}\left(\frac{\mathrm{one}}{2.7}+\frac{0.20}{\mathrm{1,0}}\right)=0.05$$

.

Thanks to the possibility of determining the air content in the soil, it becomes possible to more accurately calculate the deformation characteristics of soils, which leads to a more accurate calculation of the foundations. Refinement of the calculation of foundations leads to lower costs without compromising the reliability of buildings.

Industrial application. The invention can be successfully applied to calculate the air contained in the thawed soil.

Claims (1)

The method of determining the air content in the thawed soil, including sampling the soil, weighing and determining its volume, moisture, characterized in that it further drying the soil sample, determine the volume of solid particles of the soil, the density of dry soil, the density of solid particles, and then determine the relative content air in the thawed soil, and the calculation of the air content in the thawed soil is performed according to the formula
$$\frac{V_a}{V}=\mathrm{one}-{\rho }_d\left(\frac{\mathrm{one}}{{\rho }_s}+\frac{w}{{\rho }_w}\right),$$

where V _a is the volume of air in the sample of thawed soil;
V is the volume of the sample;
$${\rho }_d=\frac{m_d}{V},$$

dry soil density
where m _d is the mass of a dry soil sample;
$${\rho }_s=\frac{m_d}{V_d},$$

particle density
where V _d is the volume of solid particles of the sample,
$$w=\frac{m-m_d}{m_d},$$

soil moisture
where m is the mass of the soil sample; ρ _w is the density of water.