Transparent soil with high transparency and high similarity with natural soil

Abstract

The invention discloses transparent soil with high transparency and high similarity with natural soil and a preparation method of the transparent soil. The transparent soil comprises transparent particles, transparent pore liquid and an additive. The refractive indexes of the transparent particles and the transparent pore liquid are consistent, and the contact infiltration characteristic of the particle surfaces and the liquid is improved through the surfactant, so that the transparent soil with higher transparency, such as sandy soil, clay and floury soil, is obtained. Hydrophilic fumed silica is matched with polar pore liquid or hydrophobic fumed silica is matched with non-polar pore liquid to prepare high-strength transparent clay or silt with mechanical properties highly similar to those of natural clay or silt. According to the invention, the clay or silt consolidation time can be greatly shortened. The transparent soil with high transparency and high similarity with natural soil can improve the geometric dimension of a transparent soil model, reduce the dimension difference between a model test and a real engineering problem, and provide a more excellent method for researching various geotechnical geological engineering problems.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical and geological engineering, and particularly to a transparent soil with high transparency and high similarity to natural soil and its usage method. Background Art

[0002] Due to its unique transparent property, the transparent soil experimental technology can realize the whole-process visualization of the deformation and disaster of underground soil mass, and has currently become an important test method for studying the soil-structure deformation interaction in the fields of geotechnical and geological engineering. Currently, the widely used materials include transparent sand represented by fused quartz, transparent clay represented by precipitated silica, lithothamnium, etc., and a small amount of sand-clay mixture (silt). However, due to the crushing and processing technology of the fused quartz particles, there are actually some tiny defects and compression cracks on the particle surface, which results in that the current transparent sand can only ensure complete transparency within a size range of 20 cm. When the size is larger, the transparency will decrease sharply due to light scattering. For transparent clay, on the one hand, the transparency of precipitated silica is also not good; on the other hand, since the existing transparent clay formula does not consider the interaction between soil-water particles, there are still significant differences between the existing transparent clay and natural clay in terms of mechanical properties. For the transparent sand-clay mixture, it has both the above problems. In the prior art, it is considered to use hydrophobic fumed silica mixed with fused quartz to prepare the transparent sand-clay mixture, but it does not solve the problem of low transparency of the transparent soil in a large size range. In addition, when the existing transparent soil model device is consolidated, the single-sided drainage consolidation method is always adopted, which has a high consolidation time consumption and it is extremely difficult to consolidate the bottom of the model. Therefore, there is still a lack of a set of faster and more efficient consolidation means.

[0003] Therefore, it is of great significance to develop a method for preparing a transparent soil with high similarity and high transparency to natural soil. Summary of the Invention

[0004] The purpose of the present invention is to provide a transparent soil with high transparency and high similarity to natural soil, which is characterized in that it includes transparent particles, transparent pore liquid, and additives;

[0005] The transparent particles include non-cohesive fused quartz particles and any one of hydrophilic fumed silica and hydrophobic fumed silica;

[0006] The transparent pore liquid is selected from any one of non-polar pore liquid and polar pore liquid; the polar pore liquid is an aqueous solution of inorganic salt; the non-polar pore liquid is a mixture of two or more liquid alkanes;

[0007] The additives include surfactants, and 0 to 2 of stabilizers and tracers. A transparent soil with high transparency and high similarity to natural soil - 1 -

[0008] Furthermore, by adjusting the ratio of the transparent pore liquid to the transparent particles, the refractive index is the same as that of the transparent particles;

[0009] When the transparent pore liquid is a polar pore liquid, by changing the concentration of the inorganic salt, it is formulated to have the same inherent refractive index as the transparent particles;

[0010] When the transparent pore liquid is the non-polar pore liquid, by formulating the ratio of each liquid organic alkane, it reaches the same inherent refractive index as the transparent particles.

[0011] Furthermore, the polar pore liquid can be an aqueous solution of a high refractive index inorganic salt, such as an aqueous solution of sodium iodide, etc.; the non-polar pore liquid can be a mixture of two or more liquid organic alkanes, such as a mixture of n-dodecane and No. 15 white oil, etc.; the refractive index of the polar pore liquid is formulated to be the same as the inherent refractive index of the transparent particles by changing the concentration of the inorganic salt; the inorganic salt concentration of the non-polar pore liquid depends on the type of salt. For example, for an aqueous solution of sodium iodide, a mass ratio of anhydrous sodium iodide to distilled water of 1.3:1 can reach the same refractive index of 1.458 as the transparent particles; the refractive index of the non-polar pore liquid is made the same as the inherent refractive index of the transparent particles by formulating a mixture of two or more liquid organic alkanes. The refractive index of the non-polar pore liquid generally has temperature sensitivity, so the formulation process should be based on temperature. At 23 degrees Celsius, a volume ratio of No. 15 white oil to n-dodecane of 5:2 can reach the same refractive index of 1.458 as the transparent particles.

[0012] Furthermore, the surfactant is used to improve the affinity effect between the transparent particles and the pore liquid; the stabilizer is used to ensure the chemical stability of the transparent pore liquid, such as sodium thiosulfate; the tracer is used to enhance the image recognition effect, such as tracer particles and fluorescent agents; for cohesive soil (including non-cohesive fused quartz particles and fumed silica), a tracer of 0.01% of the particle mass also needs to be added during the filling process;

[0013] The present invention also claims to protect a method for preparing a transparent soil with high transparency and high similarity to natural soil. In this method, the auxiliary equipment used includes a pretreatment container, a vacuum saturation device, an optimization model box, and a refractive index measurement device;

[0014] The method includes the following steps:

[0015] 1) Prepare transparent particles and pore liquid:

[0016] 1.1) Measure the refractive index of the transparent particles;

[0017] 1.2) Adjust the ratio of each component in the transparent pore liquid according to the refractive index measured in step 1.1) until the refractive index of the transparent pore liquid is the same as that of the transparent particles;

[0018] 2) Pretreat the transparent particles:

[0019] 2.1) Weigh the transparent particles to be prepared, and then weigh a transparent soil - 2 with high transparency and high similarity to natural soil according to 20% of the mass of the transparent particles -

[0020] The prepared transparent pore liquid;

[0021] 2.2) Add a surfactant accounting for 1% of its mass to the weighed transparent pore liquid; pour the transparent particles to be treated and the treated transparent pore liquid into the pretreatment container successively, stir well, and place it in a vacuum saturation device for continuous vacuum suction for several hours to obtain pretreated transparent soil;

[0022] 3) Fill the model:

[0023] Fill the pretreated transparent soil into the optimized model box layer by layer; after filling to the predetermined height, slowly inject the transparent pore liquid into the optimized model box from the outside through the drain hole or exhaust pipe;

[0024] For non - cohesive particles (only containing non - cohesive fused quartz particles), stop injecting when the transparent pore liquid covers its top surface; for cohesive particles and mixed particles (containing non - cohesive fused quartz particles and fumed silica), the injection volume of the transparent pore liquid needs to be determined according to the liquid limit of the soil.

[0025] 4) Vacuum exhaust. Place the filled optimized model box in a vacuum saturation device for vacuum exhaust saturation treatment until the soil sample is completely transparent and then stop.

[0026] 5) Pre - consolidation. After pumping out the vacuum, apply static loads step by step on the top of the optimized model box for consolidation. Vacuum pumping can be assisted during the process to accelerate consolidation; stop when the settlement deformation is almost unchanged, then the consolidation is completed.

[0027] Furthermore, in step 1), the refractive index measuring device includes a spectrophotometer and an Abbe refractometer. The former can measure the refractive index of the transparent particles, and the latter can measure the refractive index of the transparent pore liquid;

[0028] Furthermore, in step 2), the pretreatment container is used to premix the transparent particles and the transparent pore liquid, and add surfactants and stabilizers for pretreatment;

[0029] Further, in step 3), the optimized model box (1) is a hexahedral transparent model box with an open top surface; drain holes (3) may be reserved at the bottom of the four side surfaces of the optimized model box (1), or exhaust pipes (4) may be provided at the four side corners.

[0030] Further, in step 2), when pre-treating the polar pore liquid, a stabilizer with a mass ratio of 0.1% thereof needs to be added;

[0031] Further, in step 3), when filling, when using the optimized model box, a thin layer of coarse-grained fused quartz is filled at the bottom of the model box to cover the bottom ends of the drain holes or exhaust pipes; then the pre-treated transparent soil is filled into the optimized model box in layers; for cohesive soil containing fumed silica, a tracer also needs to be added during the filling process; after filling to a predetermined height, a transparent soil with high transparency and high similarity to natural soil - 3 -

[0032] Slowly inject the transparent pore liquid into the optimized model box from the outside through the drain holes or exhaust pipes, and the optimized model box can be gently tapped and vibrated during the injection process.

[0033] The technical effects of the present invention are beyond doubt, and the beneficial effects of the present invention are as follows:

[0034] 1) A method for preparing a transparent soil with high similarity and high transparency to natural soil can significantly improve the transparency of the current transparent soil material and improve its similarity in mechanical properties to natural soil, and can increase the geometric size of the transparent soil model, reducing the size difference between the model test and the real engineering problem.

[0035] 2) A pre-treatment method for transparent particles is proposed. After adding an appropriate surfactant to the transparent pore liquid, pre-mixing and vacuum pumping treatment are carried out with the transparent particles. Reduce the surface tension of the pore liquid, making it easier to enter the fine structures such as defects and compression cracks on the surface of the non-viscous fused quartz particles (such as Figure 4 ), can be in full contact with the transparent pore liquid, thereby reducing the air in the fine structures, and then enhancing the transparency of the soil body.

[0036] 3) For the cohesive particles, the materials can be hydrophilic and hydrophobic types, mainly using the hydrophilic and hydrophobic characteristics of their surface groups; for the hydrophilic type, mainly using the affinity between the silanol groups and water to generate macroscopic cohesion; for the hydrophobic type, mainly using the new affinity between alcohol and organosilicon groups and oil to generate macroscopic cohesion. Figure 5 The Fourier infrared diagrams before and after the combination of hydrophilic fumed silica and water are given, and it can be seen that significant silanol groups are generated. Therefore, according to the characteristics of the particle material, by matching an appropriate polar or non-polar pore liquid, a strong intermolecular force can be generated between the particles and the liquid, thereby enhancing the macroscopic strength of the material and finally achieving the purpose of being similar to natural soil, such asFigure 6 as shown

[0037] 4) The optimized model box is improved to a double-sided drainage method from top to bottom, supplemented by methods such as vacuum preloading, which can greatly shorten the consolidation time of cohesive soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flowchart of the configuration method;

[0039] Figure 2 is a schematic diagram of the optimized model box Figure 1 ;

[0040] Figure 3 is a schematic diagram of the optimized model box Figure 2 ;

[0041] Figure 4 SEM image of the surface structure of fused quartz

[0042] Figure 5 is a Fourier infrared spectrum of the interaction between hydrophilic fumed silica and water

[0043] Figure 6 is a comparison chart of the mechanical properties of hydrophilic fumed silica and natural clay. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The present invention will be further described below in conjunction with embodiments, but it should not be understood that the above-mentioned subject matter scope of the present invention is limited to the following embodiments. Without departing from the above technical idea of the present invention, various substitutions and changes made according to ordinary technical knowledge and conventional means in the art should be included in the protection scope of the present invention.

[0045] A transparent soil with high transparency and high similarity to natural soil

[0046] Example 1:

[0047] A transparent soil with high transparency and high similarity to natural soil, characterized in that it comprises transparent particles, a transparent pore liquid, and an additive;

[0048] In the embodiment, when the viscous particles are hydrophilic fumed silica and are combined with a polar pore liquid, a polar transparent clay with cohesion can be obtained. Specifically:

[0049] The transparent particles are fused quartz particles with a particle size greater than 0.1 mm and hydrophilic fumed silica with a particle size less than 50 nm;

[0050] The transparent pore liquid is an aqueous solution of polar sodium iodide; in the examples, the refractive index of the polar pore liquid is adjusted to be the same as the inherent refractive index of the transparent particles by changing the concentration of the inorganic salt. For example, in the experiment, when the mass ratio of anhydrous sodium iodide to distilled water is 1.3:1, the refractive index of 1.458 same as that of transparent particle 1 can be achieved.

[0051] The additives include surfactants, stabilizers, and tracers (tracking particles and fluorescent agents). In the examples, the surfactant is polycarboxylate, the stabilizer is sodium thiosulfate, and the ratio of the tracers is 20∶1∶1.

[0052] The additives account for 0.2% of the total mass of the transparent soil.

[0053] Example 2:

[0054] A transparent soil with high transparency and high similarity to natural soil, characterized by comprising transparent particles, a transparent pore liquid, and additives;

[0055] In the examples, when the viscous particles are hydrophobic fumed silica, cohesive non-polar transparent clay can be obtained by combining with non-polar pore liquid. Specifically:

[0056] The transparent particles are fused quartz particles with a particle size greater than 0.1 mm and hydrophobic fumed silica with a particle size less than 50 nm;

[0057] The transparent pore liquid is a mixture of two or more liquid organic alkanes that are non-polar. In the examples, a mixture of n-dodecane and white oil No. 15 is used. The refractive index of the non-polar pore liquid is adjusted to be the same as the inherent refractive index of the transparent particles by mixing two or more liquid organic alkanes. The refractive index of the non-polar pore liquid generally has temperature sensitivity, so the mixing process should be based on temperature. For example, in the experiment, at 23 °C, when the volume ratio of white oil No. 15 to n-dodecane is 5:2, the refractive index of 1.458 same as that of the transparent particles can be achieved.

[0058] The additives include surfactants and tracers (tracking particles and fluorescent agents). Implement a transparent soil with high transparency and high similarity to natural soil - 5 -

[0059] In the examples, the ratio of the polycarboxylate surfactant to the tracer is 20∶1.

[0060] The additives account for 0.2% of the total mass of the transparent soil.

[0061] Example 3:

[0062] The main structure of this embodiment is the same as any one of Embodiments 1 to 2. Further, the pretreatment container is used to premix the transparent particles and the transparent pore liquid 2 in advance, and surfactants and stabilizers are added for pretreatment to enhance the contact effect between the surface of the transparent particles and the transparent pore liquid.

[0063] Embodiment 4:

[0064] The main structure of this embodiment is the same as any one of Embodiments 1 to 3. Further, the refractive index measuring device includes a spectrophotometer and an Abbe refractometer. The former can measure the refractive index of the transparent particles, and the latter can measure the refractive index of the transparent pore liquid.

[0065] Embodiment 5:

[0066] The main structure of this embodiment is the same as any one of Embodiments 1 to 4. Further, the optimization model box 1 is a hexahedral transparent model box with an open top surface. Drainage holes 2 can be reserved at the bottom of the four side surfaces of the optimization model box 1, or exhaust pipes 3 can be provided at the four side corners.

[0067] Embodiment 6:

[0068] The main structure of this embodiment is the same as any one of Embodiments 1 to 5. A method for preparing transparent soil with high transparency and high similarity to natural soil includes the following steps:

[0069] 1) Prepare the pore liquid. First, accurately measure the refractive index of the transparent particles using a spectrophotometer. Then, according to this refractive index, adjust the mass ratio or volume ratio of the components in the transparent pore liquid, and measure it with an Abbe refractometer until the refractive index of the transparent pore liquid is the same as that of the transparent particles.

[0070] 2) Pretreat the transparent particles. First, weigh the transparent particles to be prepared, and then weigh 20% of the prepared transparent pore liquid according to the mass of the transparent particles. Add 1% of the surfactant by mass to the weighed transparent pore liquid. For polar pore liquids represented by sodium iodide, a stabilizer with a mass ratio of 0.1% also needs to be added. Pour the transparent particles to be treated and the treated transparent pore liquid into the pretreatment container in sequence, stir well, and place them in a vacuum saturation device for continuous vacuum suction for several hours. Obtain pretreated transparent soil.

[0071] 3) Fill the model. First, fill a thin layer of coarse-grained fused quartz at the bottom of the optimization model box 1 to cover the bottom end of the drainage hole 2 or the exhaust pipe 3. Then, layer by layer fill the pretreated transparent soil into the optimization model box 1. For cohesive soil, during the filling process, a kind of high-transparency and high-similarity-to-natural-soil transparent soil - 6 -

[0072] A tracer with a mass of 0.01%. After filling to the predetermined height, slowly inject transparent pore fluid into the optimized model box 1 from the outside through the drain hole 2 or the exhaust pipe 3. During the injection process, the optimized model box 1 can be gently tapped and vibrated. For non-cohesive particles, the injection can be stopped when the transparent pore fluid covers its top surface. For cohesive particles and mixed particles, the injection volume of the transparent pore fluid needs to be determined according to the liquid limit of the soil.

[0073] 4) Vacuum exhaust. Place the filled optimized model box 1 into the vacuum saturation equipment for vacuum exhaust saturation treatment until the soil sample is completely transparent and then stop.

[0074] 5) Preloading consolidation. After pumping out the vacuum, gradually apply static load consolidation on the top of the optimized model box 1. During the process, vacuum pumping can be assisted to accelerate consolidation. Stop when the settlement deformation is almost unchanged, then the consolidation is completed.

Claims

1. A transparent soil with high transparency and high similarity to natural soil, characterized by: It includes the transparent particles, transparent pore liquid, and additives; The transparent particles include non-sticky fused quartz particles, and any one of hydrophilic fumed silica and hydrophobic fumed silica; The transparent pore liquid is selected from any one of a non-polar pore liquid and a polar pore liquid; the polar pore liquid is an aqueous solution of an inorganic salt; the non-polar pore liquid is a mixed liquid of two or more liquid organic alkanes; The additives include surfactants, and 0 to 2 of stabilizers and tracers.

2. The transparent soil with high transparency and high similarity to natural soil according to claim 1, characterized in that: By adjusting the ratio of the transparent pore liquid to the transparent particles, the transparent pore liquid has the same refractive index as the transparent particles; When the transparent pore liquid is a polar pore liquid, the concentration of the inorganic salt is changed to be the same as the intrinsic refractive index of the transparent particles; When the transparent pore liquid is the non-polar pore liquid, the inherent refractive index is the same as that of the transparent particles by adjusting the proportions of the liquid organic alkanes.

3. The transparent soil with high transparency and high similarity to natural soil according to claim 1, characterized in that: The material of the non-viscous fused silica particles is fused silica with a particle size greater than 0.1 mm and a purity greater than 99.99%.

4. The transparent soil with high transparency and high similarity to natural soil according to claim 1, characterized in that: The polar transparent pore liquid is selected from an aqueous sodium iodide solution.

5. The transparent soil with high transparency and high similarity to natural soil according to claim 1, characterized in that: The non-polar transparent pore liquid is selected from a mixture of n-dodecane and No. 15 white oil.

6. The transparent soil with high transparency and high similarity to natural soil according to claim 1, characterized in that: The stabilizer is selected from sodium thiosulfate.

7. The transparent soil with high transparency and high similarity to natural soil according to claim 1, characterized in that: The tracer is a tracer particle and / or a fluorescent agent.

8. A method for preparing transparent soil with high transparency and high similarity to natural soil according to claims 1 to 7, characterized in that: The following steps are involved: 1) Prepare transparent particles and pore liquid: 1.1) Determine the refractive index of transparent particles; 1.2) According to the refractive index measured in step 1.1), the ratio of each component in the transparent pore liquid is adjusted until the refractive index of the transparent pore liquid is the same as that of the transparent particles; 2) Pretreatment of transparent particles: 2.1) Weigh the transparent particles to be prepared, and then weigh the prepared transparent pore liquid according to 20% of the mass of the transparent particles; 2.2) Adding a surfactant accounting for 1% by weight to the weighed transparent porous liquid; pouring the transparent particles to be treated and the treated transparent porous liquid into the pretreatment container in sequence, stirring them thoroughly, and placing them in a vacuum saturation device for vacuum suction for several hours to obtain pretreated transparent soil; 3) Filling model: Fill the pretreated transparent soil into the optimized model box in layers; after filling to a predetermined height, slowly inject transparent porous liquid into the optimized model box from the outside through a drainage hole or an exhaust pipe; 4) Vacuum exhaust: Place the filled optimized model box into the vacuum saturation equipment for vacuum exhaust saturation treatment until the soil sample is completely transparent. 5) Pre-compression consolidation: After the vacuum is drawn, static load consolidation is applied step by step on the top of the optimized model box. During the process, vacuum drawing can be used to accelerate the consolidation. The consolidation is completed when the settlement deformation remains almost unchanged.

9. A method for preparing transparent soil with high transparency and high similarity to natural soil according to claim 8, characterized in that: In step 1), the refractive index measuring device includes a spectrophotometer and an Abbe refractometer, the former can measure the refractive index of transparent particles, and the latter can measure the refractive index of transparent porous liquid; In step 2), the pretreatment container is used to mix the transparent particles and the transparent pore liquid in advance, and add a surfactant and a stabilizer for pretreatment; In step 3), the optimized model box (1) is a hexahedral transparent model box with an open top; drainage holes (2) can be reserved at the bottom of the four sides of the optimized model box (1), or exhaust pipes (3) are set at the four corners; the injection amount of the transparent pore liquid needs to be determined according to the soil liquid limit.

10. The method for preparing transparent soil with high transparency and high similarity to natural soil according to claim 9, characterized in that: In step 2), for the pretreatment of the polar pore liquid, a stabilizer with a mass ratio of 0.1% is also added; In step 3), when filling, when an optimized model box is used, a thin layer of coarse-grained fused quartz is filled at the bottom of the model box, covering the drainage hole or the bottom of the exhaust pipe; then the pretreated transparent soil is filled into the optimized model box in layers; for clay containing fumed silica, a tracer is also required during the filling process; after filling to a predetermined height, a transparent porous liquid is slowly injected into the optimized model box from the outside through the drainage hole or the exhaust pipe, and the optimized model box can be lightly tapped and vibrated during the injection process.

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