Application of a fluorine-containing polymer in preparation of transparent frozen soil

Abstract

Particles of a fluorine-containing polymer used as a transparent solid material in an artificial transparent frozen soil is provided. The fluorine-containing polymer is poly[4,5-difluoro-2,2bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene], with a refractive index of 1.31 and a density of 2.1-2.3 g/cm.sup.3. The particles have a particle diameter of 0.25-2.0 mm or a particle diameter 0.074 mm, and have irregular shapes. When particles of the fluorine-containing polymer are used as a transparent solid material for preparing a transparent frozen soil, the prepared transparent frozen soil has high transparency, low price, no toxicity and no harm, good similarity with the properties of a natural frozen soil body, can substitute natural frozen soil, is used for simulating complicated geological conditions, and is effectively used in model tests in geotechnical engineering.

Claims

1. An artificial transparent frozen soil including a transparent solid material comprising particles of a fluorine-containing polymer, wherein: the particles of the fluorine-containing polymer have a particle diameter of 0.25-2.0 mm, and have irregular shapes, and the fluorine-containing polymer is poly[4,5-difluoro-2,2bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] with a refractive index of 1.31, and a density of 2.1-2.3 g/cm.sup.3.

2. The artificial transparent frozen soil according to claim 1, wherein: 10-50 wt % of the particles of the fluorine-containing polymer have a particle diameter greater than or equal to 0.25 mm and smaller than 0.5 mm, 10-50 wt % of the particles of the fluorine-containing polymer have a particle diameter greater than or equal to 0.5 mm and smaller than 1.0 mm, 10-50 wt % of the particles of the fluorine-containing polymer have a particle diameter greater than or equal to 1.0 mm and smaller than 1.5 mm, and 10-50 wt % of the particles of the fluorine-containing polymer have a particle diameter greater than or equal to 1.5 mm and smaller than 2.0 mm.

3. The artificial transparent frozen soil according to claim 1, further comprising particles of ice and colorless pore fluid.

4. The artificial transparent frozen soil according to claim 3, wherein the particles of ice have a particle diameter of 0.1-0.5 mm, and the colorless pore fluid is purified water.

5. The artificial transparent frozen soil according to claim 3, wherein the mass of the particles of the fluorine-containing polymer is equal to the combined mass of the particles of ice and the colorless pore fluid.

6. The artificial transparent frozen soil according to claim 3, having a density of 1.53-2.0 g/cm.sup.3, a weight density of 15-20 kN/m.sup.3, a compactness of 20-80%, an internal friction angle of 30°-31°, an elastic modulus of 8-61 MPa, and a Poisson ratio of 0.2-0.4.

7. An artificial transparent frozen soil including particles of ice, colorless pore fluid, and a transparent solid material comprising particles of a fluorine-containing polymer, wherein: the particles of the fluorine-containing polymer have a particle diameter 0.074 mm, and have irregular shapes, and the fluorine-containing polymer is poly[4,5-difluoro-2,2bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] with a refractive index of 1.31, and a density of 2.1-2.3 g/cm.sup.3.

8. The artificial transparent frozen soil according to claim 7, wherein the particles of ice have a particle diameter ≦0.074 mm, and the colorless pore fluid is purified water.

9. The artificial transparent frozen soil according to claim 7, wherein the mass of the particles of the fluorine-containing polymer is equal to the combined mass of the particles of ice and colorless pore fluid.

10. The artificial transparent frozen soil according to claim 7, having a density of 1.63-2.1 g/cm.sup.3, a weight density of 16-21 kN/m.sup.3, a consolidation degree with an OCR of 0.8-3, an internal friction angle of 19°-22°, a cohesion of 1-3 kPa, an elastic modulus of 5-9 MPa, and a Poisson ratio of 0.2-0.3.

Description

PARTICULAR EMBODIMENTS

Example 1

(1) Application of a fluorine-containing polymer in the preparation of a transparent frozen soil: it is used as a transparent solid material while in the preparation of a transparent frozen soil, said fluorine-containing polymer is particles with the particle diameter of 0.25-2.0 mm, and its particles have irregular shape, and are Teflon AF 1600 produced by American DuPont Company, with the refractive index of 1.31, and the density of 2.1-2.3 g/cm.sup.3.

(2) A production method for the preparation of a transparent frozen oil from the above fluorine-containing polymer comprises the following steps:

(3) (1) material preparation: the dosages of the fluorine-containing polymer, the cube ice and the colorless pore fluid are calculated according to the test conditions and the sample size dimensions; said fluorine-containing polymer is particles with the particle diameter ≦0.074 mm, and is subjected to impurity cleaning and oven dried, and its particles have irregular shape, and are Teflon AF 1600 produced by American DuPont Company, with the refractive index of 1.31, and the density of 2.1-2.3 g/cm.sup.3, said fluorine-containing polymer particles with the particle diameter greater than or equal to 0.25 mm and smaller than 0.5 mm account for 10-50%, those with the particle diameter greater than or equal to 0.5 mm and smaller than 1.0 mm account for 10-50%, those with the particle diameter greater than or equal to 1.0 mm and smaller than 1.5 mm account for 10-50%, those with the particle diameter greater than or equal to 1.5 mm and smaller than 2.0 mm account for 10-50%, and in terms of weight, the sum is 100%; said cube ice is obtained by mashing a frozen whole ice block, with the particle diameter of 0.1-0.5 mm; the colorless pore fluid is water, and in order not to affect the refractive index, said water is purified water;

(4) the dosages of the fluorine-containing polymer, the particle ice and the colorless pore fluid are determined according to test conditions and the sample size dimension;

(5) the sample of the example has the water content of 100.0%, the dry density of 0.55 g/cm.sup.3, and the sample size (height of 125.0 mm and diameter of 61.8 mm), the temperature of the cryogenic laboratory is of −6.0° C., the mass of the fluorine-containing polymer particles (the mass of particles=dry density×sample volume) required for preparing a sample is calculated to be 206.0 g, and the total water content (water content of 100.0%, and the mass of the total water content is equal to the mass of particles) is 206.0 g; and since sand soil has the non-frozen water content about 15% when the temperature is at −6.0° C., the mass of purified water added in the preparation process of the sample should be 30.9 g, and the mass of the cube ice is 175.1 g;

(6) (2) blending: in the −6.0° C. cryogenics laboratory, firstly the fluorine-containing polymer particles and the particle ice determined in step (1) are stirred uniformly, loaded into a mold by 2-3 batches for the preparation of a sample, and compacted layer by layer, to the designed compactness of 70%; then water is added into the mold, and fills the gaps between the fluorine-containing polymer particles and the cube ice;

(7) (3) vacuuming: a vacuuming device is utilized to remove bubbles residual inside the sample, so that the sample reaches a fully saturated state; and

(8) (4) freezing: the sample is loaded in a −20° C. cryogenic box and frozen for 48 h, so as to prepare a transparent frozen soil simulating saturated frozen clay, the physical properties of which are: density of 1.9 g/cm.sup.3, weight density of 19 kN/m.sup.3, and compactness of 70%; and the mechanical properties are: internal friction angle of 20°, cohesion of 3 kPa, elasticity modulus of 40 MPa, and Poisson ratio of 0.3.

(9) Said transparent frozen soil of the example can be used for simulating saturated frozen sand soil.

Example 2

(10) The preparation steps are the same as those of the example 1, and the difference is, in step (1), fluorine-containing polymer particles of the density of 2.1 g/cm.sup.3 are selected, fluorine-containing polymer particles with the particle diameter greater than or equal to 0.25 mm and smaller than 0.5 mm account for 20%, those with the particle diameter greater than or equal to 0.5 mm and smaller than 1.0 mm account for 30%, those with the particle diameter greater than or equal to 1.0 mm and smaller than 1.5 mm account for 30%, those with the particle diameter greater than or equal to 1.5 mm and smaller than 2.0 mm account for 20%, in terms of weight, the sum is 100%, and they are mixed uniformly;

(11) In step (2), the compactness is controlled at 30%; the physical properties of the transparent frozen soil prepared by the example are: density of 1.82 g/cm.sup.3, weight density of 18 kN/m.sup.3, and compactness 30%; and the mechanical properties are: internal friction angle of 30°, elasticity modulus of 10 MPa, and Poisson ratio of 0.35.

(12) Said transparent frozen soil of the example can be used for simulating saturated frozen sand soil.

Example 3

(13) Application of a fluorine-containing polymer in the preparation of a transparent frozen soil: it is used as a transparent solid material while in the preparation of a transparent frozen soil, and the preparation of the transparent frozen soil comprises the following steps:

(14) (1) material preparation: the dosages of the fluorine-containing polymer, the cube ice and the colorless pore fluid are calculated according to the test conditions and the sample size dimensions; said fluorine-containing polymer is particles with the particle diameter ≦0.074 mm, and is subjected to impurity cleaning and oven dried, and its particles have irregular shape, and are Teflon AF 1600 produced by American DuPont Company, with the refractive index of 1.31, and the density of 2.1-2.3 g/cm.sup.3; said cube ice is obtained by mashing a frozen whole ice block, with the particle diameter ≦0.074 mm; and the colorless pore fluid is water, and in order not to affect the refractive index, said water is purified water.

(15) The test conditions and the sample size dimension and the calculation method of the example are the same as those of example 1.

(16) In the example, the dosages of the fluorine-containing polymer particles, the cube ice and purified water are 206.0 g, 175.1 g and 30.9 g, respectively.

(17) (2) blending: in the −6.0° C. cryogenics laboratory, firstly the fluorine-containing polymer particles and the particle ice determined in step (1) are stirred uniformly, loaded into a mold by 2-3 batches for the preparation of a sample, and compacted layer by layer, to a designed compactness; then water is added into the mold, and fills the gaps between the fluorine-containing polymer particles and the cube ice;

(18) (3) vacuuming: a vacuuming device is utilized to remove bubbles residual inside the sample, so that the sample reaches a fully saturated state; and

(19) (4) consolidating: placing the sample in a consolidometer for consolidation, with the consolidation degree OCR value of 1.5; and (4) freezing: the sample is loaded in a −20° C. cryogenic box and frozen for 48 h, so as to prepare a transparent frozen soil simulating saturated frozen clay, the physical properties of which are: density of 1.93 g/cm.sup.3, and weight density of 19.1 kN/m.sup.3; and the mechanical properties are: internal friction angle of 20°, cohesion of 3 kPa, elasticity modulus of 9 MPa, and Poisson ratio of 0.3. Said transparent frozen soil of the example can be used for simulating saturated frozen sand soil.

Example 4

(20) The preparation steps are the same as those of example 3, and the difference is: in step (1), fluorine-containing polymer particles with the density of 2.1 g/cm.sup.3 are selected;

(21) in step (4), the consolidation degree OCR value is 0.8; and the physical properties of the transparent frozen soil prepared by the example are: density of 1.83 g/cm.sup.3, and weight density of 18 kN/m.sup.3; and the mechanical properties are: internal friction angle of 19°, cohesion of 1 kPa, elasticity modulus of 5.2 MPa, and Poisson ratio of 0.22. Said transparent frozen soil of the example can be used for simulating saturated frozen clay.

(22) When said fluorine-containing polymer of the present invention is used as transparent solid material for preparing a transparent frozen soil, the prepared transparent frozen soil has high transparency, low price, no toxicity and no harm, good similarity with the properties of the natural frozen soil body, can widely substitute natural frozen soil, is used for simulating complicated geological conditions, and is effectively used in model tests in the geotechnical engineering.