High-transparency clay with unconfined compressive strength and preparation method thereof

Abstract

The invention discloses a high-transparency clay with unconfined compressive strength, the clay raw material includes powder, water and tracer material, the mass ratio of the powder to water is 1:8-1:16, the mass ratio of the tracer material to water is 1:1600-1:2000 or 1:16000-1:20000, and the powder is composed of glucomannan, carrageenan and KCl; the prepared clay not only has unconfined compressive strength but also has high transparency, is close to the physical and mechanical properties of natural clay, and is used to study soil deformation and seepage in geotechnical engineering tests, as well as observe internal deformation, cracks and other phenomena. In the raw materials used in the present invention, the glucomannan and carrageenan in the powder cooperate to improve viscosity, and the molding time of the model can be accelerated and viscosity is appropriately improved by the effect of KCl, so that the prepared clay is closer to the physical and mechanical properties of natural clay.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical research, and in particular to high-transparency clay with unconfined compressive strength for geotechnical engineering research and a preparation method thereof. Background Art

[0002] Traditional methods for studying soil deformation and seepage involve embedding sensors within the soil. However, these sensors are susceptible to external environmental disturbances, making accurate measurements impossible, nor can they measure the displacement field changes associated with continuous soil deformation. Alternatively, methods such as X-ray diffraction, CT scanning, and nuclear magnetic resonance imaging (NMR) are employed. However, these methods are expensive, involve complex experimental procedures, and are therefore not widely applicable in geotechnical engineering tests. Currently, transparent soil combined with image particle velocimetry (IPV) technology can effectively address these issues, visualizing internal soil deformation. With its simplicity and low cost, it can be widely applied in geotechnical engineering tests such as soil deformation around tunnels, seepage, and soil penetration sampling. Studying the internal deformation patterns and mechanisms of soil is crucial for understanding the fundamental nature of geotechnical engineering problems. Existing transparent soils generally consist of transparent soil particles and a pore fluid with a comparable refractive index, and most exhibit the properties of uncemented sand. Studies on cohesive transparent soils are limited. Clay is widely present in nature and one of the most widely used engineering materials in engineering. It plays a very important role in geotechnical engineering. Therefore, some materials are used in the existing technology to prepare transparent clay with a certain degree of transparency, such as Laponite RD, Gelita material, a mixture of fused quartz and hydrophobic fumed silica with n-dodecane and 15# white oil, a mixture of nano-scale hydrophobic fumed silica powder with n-dodecane and 15# white oil, a mixture of amorphous silica powder with white mineral oil and n-dodecane, Aristoflex AVC polymer, a mixture of spherical silica powder with 15# white oil and n-dodecane. i However, the prepared transparent clays either have relatively low transparency or their physical and mechanical properties are still far behind those of natural clays, and some of them even have relatively high preparation costs. In addition, whether it is transparent sand or transparent clay, although some mechanical parameters can be obtained by triaxial tests through methods such as vacuum extraction, if the transparency is high, they cannot be molded alone, and they do not have unconfined compressive strength, which makes them not have the unconfined compressive characteristics of natural clay; if they can be molded alone, they have unconfined compressive strength, but they have poor transparency. In other words, in the current preparation of transparent clay, there is a problem that unconfined compressive strength and high transparency cannot be achieved at the same time.

[0003] Therefore, a new type of simulated transparent clay is needed that can simultaneously solve the problems of unconfined compressive strength and high transparency. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a high-transparency clay with unconfined compressive strength and a preparation method thereof, which can simultaneously solve the problems of unconfined compressive strength and high transparency.

[0005] The high-transparency clay with unconfined compressive strength of the present invention comprises a raw material of the clay including a powder, water and a tracer material, wherein the mass ratio of the powder to water is 1:8-1:16, and the powder is composed of glucomannan, carrageenan and KCl;

[0006] Furthermore, by mass percentage, glucomannan 47-55%, carrageenan 42-50%, KCl 0.3-3%;

[0007] Furthermore, by mass percentage, glucomannan 50%, carrageenan 48%, KCl 2%;

[0008] Furthermore, the tracer material is one of carbon nanotubes, hollow glass microbeads, and precipitated silica powder;

[0009] Furthermore, when the tracer material is carbon nanotubes or precipitated silica powder, the mass ratio of the tracer material to water is 1:16000-1:20000;

[0010] Furthermore, when the tracer material is hollow glass microspheres, the mass ratio of the tracer material to water is 1:1600-1:2000, and the outer diameter of the hollow glass microspheres is 0.05-0.1 mm.

[0011] The present invention also discloses a method for preparing high-transparency clay with unconfined compressive strength, comprising the following steps:

[0012] Heat the water, add the powder and stir, then add the tracer material and stir for 30 to 90 seconds;

[0013] Furthermore, the tracer material is added for no more than 20 seconds;

[0014] Furthermore, when the room temperature is higher than 25 degrees, the temperature of the heated water is not lower than 90°C; when the room temperature is lower than 20 degrees, the temperature of the heated water is not lower than 97°C; when the room temperature is between these two, the temperature of the heated water is 90°C-97°C.

[0015] The beneficial effects of the present invention include: the high-transparency clay with unconfined compressive strength for geotechnical engineering research and its preparation method; the prepared clay not only has unconfined compressive strength but also high transparency, and has physical and mechanical properties similar to natural clay; it is used in geotechnical engineering experiments to study soil deformation and seepage, as well as to observe internal deformation, cracks, and other phenomena. Among the raw materials used in the present invention, the combined action of glucomannan and carrageenan in the powder can increase viscosity, while the action of KCl can adaptively adjust the viscosity to be less sticky, making the prepared clay closer to the physical and mechanical properties of natural clay. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Quantitative values ​​of transparency of different tracer materials and transparent clay with different proportions. DETAILED DESCRIPTION

[0017] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0018] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0019] Example 1

[0020] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 55%, 44.5% and 0.5% respectively; the mass ratio of the tracer material (hollow glass microspheres with an outer diameter of 0.05 mm) to water is 1:2000; and the mass ratio of the powder to water is 1:8.

[0021] Example 2

[0022] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 55%, 44.5% and 0.5% respectively; the mass ratio of the tracer material (carbon nanotubes) to water is 1:20000; and the mass ratio of the powder to water is 1:10.

[0023] Example 3

[0024] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 55%, 44.5% and 0.5% respectively; the mass ratio of the tracer material (precipitated silica powder) to water is 1:16000; and the mass ratio of the powder to water is 1:12.

[0025] Example 4

[0026] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 55%, 44.5% and 0.5% respectively; the mass ratio of the tracer material (hollow glass microspheres with an outer diameter of 0.08 mm) to water is 1:2000; and the mass ratio of the powder to water is 1:14.

[0027] Example 5

[0028] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 55%, 44.5% and 0.5% respectively; the mass ratio of the tracer material (hollow glass microspheres with an outer diameter of 0.1 mm) to water is 1:2000; and the mass ratio of the powder to water is 1:16.

[0029] Example 6

[0030] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 47%, 50% and 3% respectively; the mass ratio of the tracer material (hollow glass microspheres with an outer diameter of 0.1 mm) to water is 1:1600; and the mass ratio of the powder to water is 1:8.

[0031] Example 7

[0032] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 50%, 48% and 2% respectively; the mass ratio of the tracer material (hollow glass microspheres with an outer diameter of 0.1 mm) to water is 1:1800; and the mass ratio of the powder to water is 1:9.

[0033] Example 8

[0034] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 53%, 46% and 1% respectively; the mass ratio of the tracer material (carbon nanotubes) to water is 1:19000; and the mass ratio of the powder to water is 1:11.

[0035] Embodiment 9

[0036] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 53%, 46% and 1% respectively; the mass ratio of the tracer material (carbon nanotubes) to water is 1:17000; and the mass ratio of the powder to water is 1:11.

[0037] Example 10

[0038] The high-transparency clay with unconfined compressive strength of this embodiment is composed of glucomannan, carrageenan and KCL in a mass ratio of 53%, 46% and 1% respectively; the mass ratio of the tracer material (precipitated silica powder) to water is 1:18000; and the mass ratio of the powder to water is 1:11.

[0039] The method for preparing a highly transparent clay with unconfined compressive strength in the above embodiment involves heating water, adding the powder, and stirring. After stirring the powder and water for 10 seconds, the tracer material is immediately added, with the tracer material added for no longer than 20 seconds. The mixture is then stirred for an additional 30 to 90 seconds. This completes the preparation of the transparent clay (liquid).

[0040] Pour the prepared transparent clay (liquid) into the appropriate container for the desired test, leaving it in the container for no more than 100 seconds. When the room temperature is above 25°C, the heated water temperature should be no less than 90°C; when the room temperature is below 20°C, the heated water temperature should be no less than 97°C; when the room temperature is between these two temperatures, the heated water temperature should be between 90°C and 97°C.

[0041] Quantitative determination of transparency:

[0042] The transparency of transparent clay was measured using a UV-visible-near-infrared spectrophotometer.

[0043] Pour the prepared transparent clay (liquid) into a rectangular container with a length, width and height of 50×40×20 mm respectively, and cool it for 30 to 50 minutes. At this time, the transparent clay has changed from liquid to solid.

[0044] Carefully take the solid transparency test piece out of the container and place it in the test position of the spectrophotometer. Start the spectrophotometer and the instrument will automatically complete the measurement of the transparency value of each test piece.

[0045] 1. Shear strength determination

[0046] Shear strength is measured using the most commonly used geotechnical testing instrument - direct shear apparatus.

[0047] Pour the prepared transparent clay (liquid) into the container specified for the direct shear apparatus and cool it as described above. After cooling, remove the specimen and place it in the direct shear apparatus. Determine the shear strength of the new transparent clay according to the "Operational Procedure for Geotechnical Testing." It should be noted that because the cohesion of the new transparent clay is lower than that of natural clay, a high-precision direct shear apparatus with a relatively small range is required to ensure more accurate measurement results.

[0048] 2. Determination of unconfined compressive strength

[0049] The unconfined compressive strength is measured using the most commonly used geotechnical testing instrument - the uniaxial compression apparatus.

[0050] Pour the prepared transparent clay (liquid) into the container specified by the uniaxial compression instrument and cool it according to the above method. After cooling, take out the specimen and put it into the uniaxial compression instrument to measure the uniaxial compression strength of the new transparent clay according to the provisions of the "Geotechnical Test Operating Procedures".

[0051] It should be noted that since the unconfined compressive strength of the new transparent clay is lower than that of natural clay, a high-precision uniaxial compression instrument with a relatively small range is required to ensure that the measured data is more accurate.

[0052] For all tests conducted at different ambient temperatures, the test time is inversely proportional to the ambient temperature. That is, the higher the ambient temperature, the shorter the permitted test operation time. When the ambient temperature is above 30°C, the operation time should not exceed 10 minutes. When the ambient temperature is between 26°C and 30°C, the operation time should not exceed 10 to 20 minutes (the lower value is used for higher temperatures). When the ambient temperature is between 16°C and 26°C, the permitted operation time can be increased by 1 to 2 minutes (based on the 20-minute value) for every 1°C decrease in temperature (the lower value is used for higher temperatures). When the ambient temperature is between 10°C and 16°C, the permitted operation time can be increased by 3 to 5 minutes (based on the 40-minute value) for every 1°C decrease in temperature. If refrigerated at 3 to 5°C, the storage time is 8 to 10 hours.

[0053] When placed in a refrigerator at -10 to -18°C, the storage time can be extended to 30 to 40 hours, but the permissible operating time after taking it out is no more than 5 to 15 minutes (the lower value is used when the ambient temperature is high). Once taken out of the frozen environment and tested, it cannot be stored at low temperatures again, and the sample is discarded.

[0054] Measurement results:

[0055] 1. Quantitative determination of transparency

[0056] The transparency of the transparent clays prepared in the aforementioned ratios was measured using a UV-3600 UV-Vis-NIR spectrophotometer. Three tracer-containing compounds (carbon nanotubes at a ratio of 1:20,000; hollow glass microspheres at a ratio of 1:1,600; and precipitated silica micropowder at a ratio of 1:16,000) were added to each ratio, along with a control group without tracers. Three specimens were prepared for each group, measuring 50 mm in length, width, and height (50 mm x 40 mm x 20 mm). A total of five ratios (1:8, 1:10, 1:12, 1:14, and 1:16) were used, resulting in 60 specimens. The transparent clay (liquid form) was poured into a silicone mold, cooled for 30 minutes, carefully removed, and placed in a UV-3600 UV-Vis-NIR spectrophotometer for transparency measurement.

[0057] According to the Geotechnical Experiment Operating Procedures and the requirements of data statistics, the three data of each mix ratio were statistically analyzed to obtain the transparency quantitative value of the mix ratio. The results are as follows Figure 1 shown.

[0058] 2. Shear strength determination

[0059] The shear strength of the transparent clays in the aforementioned mixes was measured using a Zhilong Technology AZJ-4 fully automatic quadruple shear tester. Four cylindrical specimens measuring Φ39.1 x 80 mm were prepared for each mix. Three tests were conducted for each of the five mixes, resulting in a total of 60 specimens.

[0060] Liquid transparent clay was poured into a stainless steel mold. After cooling for 30 minutes, the mold was carefully removed. Four specimens of the same mix were placed in an automatic direct shear apparatus to measure the shear strength of the transparent clay. Upon completion, the instrument automatically generated a parametric equation for the shear strength of the four specimens.

[0061] The shear strength results for each mix ratio are shown in the following table:

[0062]

[0063] 3. Determination of unconfined compressive strength

[0064] The unconfined compressive strength of the transparent clays with the aforementioned mixes was measured using a Zhilong Technology AMY-2 fully automatic uniaxial compression instrument. Three cylindrical specimens measuring Φ39.1 × 80 mm were prepared for each mix. A total of 15 specimens were prepared for five mixes.

[0065] Liquid transparent clay was poured into a stainless steel mold and allowed to cool for 30 minutes. The mold was then carefully removed. Three specimens of the same mix were then placed in a fully automated uniaxial compression instrument to measure the unconfined compressive strength of the transparent clay. Upon completion, the instrument automatically generated an unconfined compressive strength curve for each specimen.

[0066] The unconfined compressive strength value of each specimen was determined according to the Geotechnical Experiment Operating Procedures. According to the requirements of data statistics, the three data of each mix ratio were statistically analyzed to obtain the unconfined compressive strength value of the mix ratio. The results are shown in the following table:

[0067] Ratio Unconfined compressive strength value 1：8 14kpa 1：10 16kpa 1：12 20kpa 1：14 21kpa 1：16 14kpa

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high transparency clay with unconfined compressive strength, characterized by: The clay raw material includes powder, water and a tracer material, wherein the mass ratio of the powder to water is 1:10-1:16, and the powder is composed of glucomannan, carrageenan and KCl; in terms of mass percentage, the glucomannan is 47-55%, the carrageenan is 42-50%, and the KCl is 0.3-3%; the tracer material is one of carbon nanotubes, hollow glass microspheres, and precipitated silica micropowder; when the tracer material is carbon nanotubes or precipitated silica micropowder, the mass ratio of the tracer material to water is 1:16000-1:20000; when the tracer material is hollow glass microspheres, the mass ratio of the tracer material to water is 1:1600-1:2000.

2. The high transparency clay with unconfined compressive strength according to claim 1, characterized in that: The outer diameter of the hollow glass microspheres is 0.05-0.1 mm.

3. The high transparency clay with unconfined compressive strength according to claim 1, characterized in that: By mass percentage, glucomannan 50%, carrageenan 48%, KCl 2%.

4. The method for preparing high-transparency clay with unconfined compressive strength according to claim 1, characterized in that: The following steps are involved: Heat the water, add the powder and stir, then add the tracer material and stir for 30 to 90 seconds.

5. The method for preparing high-transparency clay with unconfined compressive strength according to claim 4, characterized in that: The tracer material is added for no more than 20 seconds.

6. The method for preparing high-transparency clay with unconfined compressive strength according to claim 4, characterized in that: When the room temperature is higher than 25 degrees, the heated water temperature shall not be lower than 90 degrees; when the room temperature is lower than 20 degrees, the heated water temperature shall not be lower than 97 degrees.

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