Preparation method of soft soil similar material meeting transparency and similarity requirements

Abstract

The invention discloses a preparation method of a soft soil similar material meeting the requirements of transparency and similarity, which ensures the transparency of the material by accurately controlling the preparation of mixed oil, calibrating an Abbe refractometer and standardizing the mixing ratio of n-dodecane to 15 # white oil and the stirring and standing process; the white carbon black dispersion and quartz sand mixing and stirring processes are strictly standardized, and it is guaranteed that the mechanical properties such as the material weight and the internal friction angle are similar to those of real soft soil. Meanwhile, strict operation standards are set in the steps of model filling, air exhaust saturation, sample sampling and the like, the environment and measuring tool conditions are controlled, and parameters and reserved samples are completely recorded. The method effectively solves the problems that transparency and mechanical properties of a traditional material are difficult to balance, and configuration lacks accuracy and repeatability, and provides a reliable soft soil similar material preparation means for geotechnical engineering research and engineering practice.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a configuration method of soft soil-like materials that meets transparency and similarity requirements. Background Art

[0002] In research and engineering practice in fields such as geotechnical engineering and geomechanics, soft soil analogue materials are often used to simulate the properties of real soft soil in order to conduct model tests, verify theoretical analysis, and optimize engineering design. As a special type of soil, soft soil has complex physical and mechanical properties and engineering characteristics, making the study of soft soil analogue materials of great practical significance. For example, in projects such as subway tunnel excavation and large-scale building foundation treatment, simulating the deformation and bearing characteristics of soft soil foundations can effectively evaluate the feasibility and safety of engineering solutions. However, traditional soft soil analogue materials have difficulty meeting the dual requirements of transparency and similarity at the same time, and have many limitations in practical applications.

[0003] The primary drawback of existing soft soil-like materials is the difficulty in achieving a balance between high transparency and similar mechanical properties. While some materials possess a certain degree of transparency, their mechanical parameters, such as density, internal friction angle, and cohesion, differ significantly from those of real soft soil, making them unable to accurately simulate the mechanical behavior of soft soil in actual engineering applications. For example, some similar materials made from transparent materials like plexiglass, while allowing for clear observation of internal structural changes, exhibit significantly different deformation moduli and strength than real soft soil, rendering the test results ineffective in guiding actual engineering applications.

[0004] Secondly, existing configuration methods lack precision and repeatability. Traditional methods lack strict standards and control parameters in terms of material ratios and manufacturing processes, resulting in large fluctuations in the performance of similar materials produced in different batches. For example, during the mixing process of mixed materials, if the stirring speed and time are not properly controlled, the materials will be unevenly mixed, affecting the final performance; and due to the lack of strict control of environmental factors (such as temperature and humidity), material performance will also deviate, making it difficult to meet the requirements of scientific research and engineering for material stability and consistency. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a method for configuring soft soil similar materials that meets the requirements of transparency and similarity.

[0006] The technical solution adopted by the present invention is a method for configuring soft soil similar materials that meet the requirements of transparency and similarity, comprising the following steps:

[0007] Step 1: Preparation of mixed oil: At room temperature of 20°C, use an Abbe refractometer to measure the refractive index of n-dodecane and 15# white oil respectively and record them; mix n-dodecane and 15# white oil in a volume ratio of 12:400, stir thoroughly and let stand, take the upper layer of impurity-free liquid, measure the refractive index of the mixed liquid with an Abbe refractometer to make it reach 1.4585, weigh and set aside;

[0008] Step 2: Wetting the binder: Divide the nano-scale silica into 8-10 groups of equal mass, add each group of silica into the prepared mixture in turn, and stir with a glass rod for more than 5 minutes after each addition to obtain a solid substance similar to a glue stick;

[0009] Step 3: Mixing the mixture: Pour the washed, dried and weighed fused quartz sand into a container, crush the binder obtained in step 2 and mix it thoroughly with the fused quartz sand to form a block structure;

[0010] Step 4: Filling the model: Fill the mixture obtained in step 3 naturally into the glass box without pressing during the filling process;

[0011] Step 5: Vacuum saturation: Prepare a mixed oil with a mass 2-3 times that of the mixed oil in step 1. First, add the same mass of oil as in step 1 into the glass box. Vacuum the test piece at a vacuum pressure of -0.1MPa for 1 hour. Then, add the remaining liquid until the liquid level just covers the solid matter. Continue to vacuum for 2 hours.

[0012] Step 6: Sample collection: Use the cover plate to squeeze the sample until it can no longer be pressed, and use a needle to absorb the excess upper liquid to obtain transparent cemented soil;

[0013] Step 7. Adjust the material ratio: When adjusting the density γ, give priority to adjusting the quartz sand particle size; adjust the material internal friction angle φ only by adjusting the glue-stone ratio; adjust the cohesion c by giving priority to adjusting the glue-stone ratio; the glue-stone ratio is the factor that mainly controls the deformation modulus E.

[0014] Furthermore, in step 1, when measuring the refractive index of n-dodecane and 15# white oil liquid, the Abbe refractometer is calibrated using a standard substance with a known refractive index. During the calibration process, the temperature is maintained at 20°C ± 0.5°C. When mixing n-dodecane and 15# white oil, the stirring speed is controlled at 200-300 rpm, the stirring time is 15-20 minutes, the two liquids are fully mixed, and the standing time is not less than 12 hours.

[0015] Furthermore, in step 2, after each group of nano-scale silica is added to the mixed liquid, circular stirring and up and down stirring are combined during stirring. The circular stirring radius is 3-5 cm, and the up and down stirring depth covers more than 80% of the depth of the mixed liquid. During the stirring process, there is a pause of 30-60 seconds every 2-3 minutes of stirring, and the temperature of the mixed liquid is controlled at 20°C-25°C.

[0016] Furthermore, in step three, before pouring the molten quartz sand into the container, the container is cleaned and dried, and there are no impurities and moisture in the container. When crushing the binder, the particle size of the binder fragments is controlled to be 2-5 mm. When mixing, first stir at a low speed for 3-5 minutes, the stirring speed is 100-150 rpm, so that the binder is initially dispersed in the quartz sand, and then stir at a high speed for 5-8 minutes, the stirring speed is 300-400 rpm.

[0017] Furthermore, in step four, a layer of release agent is pre-applied to the inside of the glass box. The release agent is a silicone release agent with a coating thickness of 0.1-0.2 mm. When filling the mixture, a layered filling method is adopted, and the thickness of each layer is 3-5 cm. After each layer is filled, a flat vibrator is used to slightly vibrate the outside of the glass box. The vibration time is 1-2 minutes, and the vibration frequency is 30-40 Hz.

[0018] Furthermore, in step five, the vacuum extraction equipment adopts a rotary vane vacuum pump, the ultimate vacuum degree of the vacuum pump reaches below -0.1 MPa, and the exhaust pipe adopts a transparent plastic tube with an inner diameter of 8-10 mm. During the first exhaust for 1 hour, the test piece in the glass box is slightly shaken every 15-20 minutes to make it easier to discharge bubbles; during the second exhaust for 2 hours, it is shaken every 30-40 minutes.

[0019] Furthermore, in step six, the cover plate is made of a plexiglass plate with a thickness of 5-8 mm, and the area of ​​the cover plate is 20%-30% larger than the area of ​​the sample. When squeezing the sample, pressure is applied by evenly placing weights on the cover plate. The total mass of the weights is adjusted according to the size of the sample, generally so that the pressure on the sample reaches 0.05-0.1 MPa. When using a syringe to absorb excess upper liquid, the inner diameter of the syringe is 1-2 mm.

[0020] Furthermore, in step seven, when adjusting the particle size of quartz sand, if the gravity γ is increased, quartz sand with a particle size range of 5.0-8.0 mm is preferably used; if the gravity γ is reduced, quartz sand with a particle size range of 0.2-0.5 mm is preferably used. When adjusting the glue-stone ratio, it is achieved by accurately weighing to increase or decrease the mass of nano-scale silica, and the adjustment accuracy is controlled within ±0.1g.

[0021] Furthermore, during the entire configuration process, all measuring instruments used, including balances, measuring cylinders, and volumetric flasks, are calibrated before use, and the calibration error is controlled within ±50% of the allowable error range. All operating processes are carried out in a clean, well-ventilated environment, and the ambient humidity is controlled at 40%-60%.

[0022] Furthermore, during the configuration process, the key parameters of each operation step, such as the refractive index of the mixed oil, the stirring time of the binder, and the particle size of the quartz sand, are recorded in detail to form an operation record document, and samples of the configured transparent binder are retained, with the number of samples retained being no less than 3, the volume of each sample being 50-100 cubic centimeters, and the sample storage time being no less than 6 months.

[0023] Beneficial Effects: The present invention proposes a method for preparing soft soil-like materials that meet transparency and similarity requirements. By precisely controlling the preparation of the mixed oil, calibrating it with an Abbe refractometer, and strictly controlling the mixing ratio of n-dodecane to 15# white oil, as well as the stirring and settling parameters, the refractive index of the mixed oil meets the requirements and the transparency of the material is guaranteed. Furthermore, during the binder wetting and mixture stirring steps, the dispersion of nano-silica and its mixing with fused quartz sand are standardized, resulting in mechanical parameters such as the material's density and internal friction angle being highly similar to those of real soft soil. To address the lack of accuracy and repeatability of traditional methods, this preparation method sets strict standards for each step, from measuring instrument calibration and environmental temperature and humidity control to material ratios and manufacturing process parameters. These parameters are precisely quantified, such as controlling the drying temperature and time of quartz sand, standardizing the binder crushing particle size, and specifying the model fill layer thickness and vibration intensity, ensuring consistent performance across different batches of materials. The high transparency enables the application of optical observation technology to intuitively analyze changes in the material's internal structure. The precise mechanical similarity ensures that the simulated experimental data can effectively guide actual engineering projects. Strict operating specifications and parameter control greatly improve the success rate and reliability of material production, reduce experimental errors and engineering risks caused by fluctuations in material properties, provide scientific and reliable material preparation methods for geotechnical engineering research, geological simulation experiments, etc., and promote technological development and engineering practice progress in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the overall steps of the present invention. DETAILED DESCRIPTION

[0025] It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of this application can be combined with each other. The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, a configuration method of soft soil similar material that meets the requirements of transparency and similarity includes the following steps:

[0027] Step 1: Preparation of mixed oil: At room temperature of 20°C, use an Abbe refractometer to measure the refractive index of n-dodecane and 15# white oil respectively and record them; mix n-dodecane and 15# white oil in a volume ratio of 12:400, stir thoroughly and let stand, take the upper impurity-free liquid, measure the refractive index of the mixed liquid with an Abbe refractometer to make it reach 1.4585, weigh and set aside;

[0028] Specifically, the refractive index of n-dodecane and 15# white oil was measured and recorded using an Abbe refractometer at room temperature of 20°C. This temperature setting is based on the fact that the optical properties of many materials are relatively stable at 20°C, ensuring the accuracy of the measurement data. The Abbe refractometer is a commonly used instrument for measuring the refractive index of liquids. To operate, a small amount of the liquid to be measured is dropped onto a prism, and the refractive index value is read through the eyepiece. Recording the refractive indices of the two base liquids provides a basis for subsequent adjustments to the mixing ratio.

[0029] Mix n-dodecane and 15# white oil in a volume ratio of 12:400. This ratio, verified through extensive experimentation, ensures that the refractive index of the resulting mixture approximates the optical properties of soft soil. To mix, first pour 15# white oil into a mixing container, then slowly add n-dodecane. Stir at 200-300 rpm for 15-20 minutes to ensure the two liquids are fully integrated. After stirring, let the mixture stand for at least 12 hours to allow any impurities to settle. After standing, remove the impurity-free upper layer and re-measure its refractive index using an Abbe refractometer. The refractive index is required to reach 1.4585. If this value is not reached, adjust the mixing ratio of the two liquids and reconstitute.

[0030] For example, in one experiment, the refractive index measured after initial mixing was 1.4570, falling short of the target value of 1.4585. Based on experimental experience, the volume of n-dodecane was increased slightly, and the mixture was stirred again, allowed to stand, and measured again until the refractive index met the requirements. Finally, the blended oil that met the standards was weighed and the amount to be used was determined based on subsequent configuration requirements, keeping it ready for later use.

[0031] Step 2: Wetting the binder: Divide the nano-scale silica into 8-10 groups of equal mass, add each group of silica into the prepared mixture in turn, and stir with a glass rod for more than 5 minutes after each addition to obtain a solid substance similar to a glue stick;

[0032] Specifically, nano-sized silica of equal weight is divided into 8-10 groups. This grouping facilitates the control of the mixing process between the silica and the mixed oil, ensuring uniform mixing and consistent results each time. Each group of silica is added sequentially to the prepared mixture, stirring with a glass rod for at least 5 minutes after each addition. A combination of circular stirring and up-and-down stirring is employed, with a stirring radius of 3-5 cm and a stirring depth that covers at least 80% of the mixture's depth to ensure the silica is fully dispersed throughout the mixture.

[0033] During the mixing process, pause for 30-60 seconds every 2-3 minutes. This is because stirring generates heat. Continuous stirring could increase the temperature of the mixture, affecting the performance of the binder. Therefore, the temperature of the mixture should be controlled between 20°C and 25°C. This ensures that the silica and the oil mix come into full contact and undergo physical adsorption, ultimately resulting in a solid material resembling a glue stick. This solid material will serve as a binder for the fused quartz sand in subsequent steps, and its quality directly affects the strength and stability of materials similar to soft soil.

[0034] For example, in one preparation, nano-silica was divided into 10 groups, each containing 5 grams. Each group of silica was added to the mixture in sequence, and the stirring method and pause time were strictly controlled during the stirring process. Ultimately, a uniform, stick-like solid material was successfully obtained. Failure to follow the stirring instructions can lead to uneven dispersion of the silica, resulting in clumping in some areas, which can affect the subsequent material properties.

[0035] Step 3: Mixing the mixture: Pour the washed, dried and weighed fused quartz sand into a container, crush the binder obtained in step 2 and mix it thoroughly with the fused quartz sand to form a block structure;

[0036] Specifically, before pouring the washed, dried, and weighed fused quartz sand into a container, the container must be cleaned and dried to ensure it is free of impurities and moisture, which can affect the quality of materials like soft soil. The drying temperature for fused quartz sand is generally controlled between 105°C and 110°C, and the drying time is at least 2 hours to ensure that the sand is completely dry. When weighing, accurately weigh the required amount of quartz sand according to the configured ratio.

[0037] Crumble the binder obtained in step 2 to a particle size of 2-5 mm to ensure thorough mixing with the quartz sand. Place the crushed binder and fused quartz sand in a container and stir at a low speed of 100-150 rpm for 3-5 minutes to initially disperse the binder in the quartz sand. Then, stir at a high speed of 300-400 rpm for 5-8 minutes to ensure a uniform mixture. High-speed stirring allows the binder to better coat the surface of the quartz sand particles, forming a stable mixture structure.

[0038] For example, during one preparation, 500 grams of fused quartz sand was weighed, the binder was crushed, and then added to the mixture. Stirring was performed at a low speed followed by a high speed, ultimately resulting in a blocky mixture. Insufficient stirring can lead to uneven distribution of the binder, resulting in inconsistent strength of the resulting soft soil-like material, compromising experimental or engineering applications.

[0039] Step 4: Filling the model: Fill the mixture obtained in step 3 naturally into the glass box without pressing during the filling process;

[0040] Specifically, before filling the model, a layer of silicone release agent (0.1-0.2 mm thick) is applied to the inside of the glass box. This release agent facilitates removal of the soft clay-like material from the glass box after the experiment is complete, preventing damage to the material from adhering to the box.

[0041] When filling the mixture, use a layered approach, with each layer 3-5 cm thick. This layered approach makes the material more compact and reduces internal voids. After each layer is completed, use a flat vibrator to gently vibrate the outside of the glass box for 1-2 minutes at a frequency of 30-40 Hz to remove some bubbles. However, avoid excessive vibration, which can damage the material's internal structure and affect its mechanical properties.

[0042] For example, when creating a soft soil-like material model with dimensions of 30 cm long, 20 cm wide, and 20 cm high, the mixture is layered and filled in four layers. Each layer is vibrated appropriately to achieve a uniform structure and a model without noticeable bubbles. Without layered filling and vibration, a large number of bubbles may remain inside the model, resulting in unstable material properties.

[0043] Step 5: Vacuum saturation: Prepare a mixed oil with a mass 2-3 times that of the mixed oil in step 1. First, add the same mass of oil as in step 1 into the glass box. Vacuum the test piece at a vacuum pressure of -0.1MPa for 1 hour. Then, add the remaining liquid until the liquid level just covers the solid matter. Continue to vacuum for 2 hours.

[0044] Specifically, prepare a mixture of oil 2-3 times the mass of the first-stage mixture to ensure that the soft soil-like material is fully saturated with the mixture during the pumping process. First, add the same mass of oil as in the first step to the glass box, and then pump the specimens at a vacuum pressure of -0.1 MPa for one hour. A vacuum of -0.1 MPa effectively removes air from the material, allowing the mixture to better penetrate the pores. The pumping equipment uses a rotary vane vacuum pump with a maximum vacuum of less than -0.1 MPa. The pumping line uses a transparent plastic tube with an inner diameter of 8-10 mm to facilitate observation of bubble discharge during the pumping process.

[0045] Then, add the remaining liquid until the liquid level just covers the solid material, and continue vacuuming in the vacuum chamber for another two hours. During the first one-hour vacuuming, gently shake the specimen in the glass chamber every 15-20 minutes to facilitate the expulsion of bubbles. During the second two-hour vacuuming, shake the specimen every 30-40 minutes. This ensures that the air inside the material is fully extracted, achieving a good saturation effect.

[0046] For example, in one experiment, the first step involved preparing 250 grams of mixed oil, using 100 grams of the oil mixture. During the initial degassing, 100 grams of the oil mixture was added. During this process, the specimen was shaken regularly, and a large number of bubbles were observed to be expelled. The remaining 150 grams of oil mixture was added and continued degassing, ultimately resulting in a well-saturated soft soil-like material. If the degassing process is not standardized, air may remain within the material, affecting the test results of its physical and mechanical properties.

[0047] Step 6: Sample collection: Use the cover plate to squeeze the sample until it can no longer be pressed, and use a needle to absorb the excess upper liquid to obtain transparent cemented soil;

[0048] Specifically, the sample is squeezed until it can no longer be moved using a cover plate made of plexiglass 5-8 mm thick, with the cover area 20%-30% larger than the sample. Pressure is applied by evenly placing weights on the cover plate, with the total mass adjusted based on the sample size, typically to a pressure of 0.05-0.1 MPa. This pressure is applied to further compact the sample and remove excess liquid.

[0049] Use a syringe with an inner diameter of 1-2 mm to aspirate the excess liquid from the upper layer. Aspirate slowly to avoid disturbing the sample surface. This ensures effective aspiration and prevents damage to the sample surface structure caused by rapid operation. This series of operations ultimately yields a transparent cemented soil.

[0050] For example, for a sample 10 cm in diameter and 10 cm in height, a suitable plexiglass plate is used as the cover, and a weight of appropriate mass is placed to compress the sample. Excess liquid is then slowly aspirated using a small-diameter needle to obtain a transparent cemented soil sample that meets the requirements. Improper sampling, such as excessive pressure or rapid aspiration, can damage the sample and render it unusable for subsequent analysis.

[0051] Step 7. Adjust the material ratio: When adjusting the density γ, give priority to adjusting the quartz sand particle size; adjust the material internal friction angle φ only by adjusting the glue-stone ratio; adjust the cohesion c by giving priority to adjusting the glue-stone ratio; the glue-stone ratio is the factor that mainly controls the deformation modulus E.

[0052] Specifically, adjusting the γ density is primarily about adjusting the quartz sand particle size. To increase the γ density, quartz sand with a particle size range of 5.0-8.0 mm is preferred; to decrease the γ density, quartz sand with a particle size range of 0.2-0.5 mm is preferred. This is because quartz sands of different particle sizes have different bulk densities, and adjusting the particle size can effectively change the material's density.

[0053] Adjusting the material's internal friction angle φ is done solely by adjusting the binder-to-cement ratio, while adjusting the cohesion c prioritizes adjusting the binder-to-cement ratio. The binder-to-cement ratio is the primary factor controlling the deformation modulus E. Adjustment of the binder-to-cement ratio is achieved by precisely weighing the amount of nano-silica, with an accuracy of ±0.1g. Changing the binder-to-cement ratio influences the degree of bonding between the binder and the quartz sand, thereby altering the material's mechanical properties, including the internal friction angle, cohesion, and deformation modulus.

[0054] For example, in one experiment, the density of a soft soil-like material needed to be increased. By replacing it with quartz sand with a particle size of 5.0-8.0 mm, the desired density was successfully achieved. If the material's cohesion needed to be adjusted, increasing the amount of nano-silica and the ratio of glue to sand effectively improved the material's cohesion. By rationally adjusting the material ratio, the various properties of soft soil-like materials can be tailored to meet the needs of different experiments or engineering applications.

[0055] Preferably, in step 1, when measuring the refractive index of n-dodecane and 15# white oil liquid, the Abbe refractometer is calibrated using a standard substance with a known refractive index. During the calibration process, the temperature is maintained at 20°C ± 0.5°C. When mixing n-dodecane and 15# white oil, the stirring speed is controlled at 200-300 rpm, the stirring time is 15-20 minutes, the two liquids are fully mixed, and the standing time is not less than 12 hours.

[0056] Specifically, the Abbe refractometer is calibrated using a reference material with a known refractive index, such as aqueous sucrose (its refractive index has precise corresponding values ​​at different concentrations). The calibration temperature is maintained at 20°C ± 0.5°C. This is because temperature fluctuations can cause changes in the refractive index of the reference material and the liquid being measured, leading to measurement errors. Measuring the refractive index of n-dodecane and 15# white oil after calibration ensures accurate data and provides a reliable basis for the proportioning of the mixed oil. During mixing, the stirring speed and time are set at 200-300 rpm for 15-20 minutes to fully blend the two liquids and form a homogeneous system. For example, in one experiment, the stirring speed was not strictly controlled, reaching only 150 rpm, resulting in stratification of the mixed oil and unstable refractive index measurements. Only after readjusting the stirring conditions did a qualified mixed oil result. A standing time of at least 12 hours allows impurities to fully settle. If the standing time is insufficient, residual impurities may affect the transparency of the mixed oil and subsequent material properties. For example, in another experiment, sampling after 8 hours resulted in poor light transmittance of the soft soil-like material produced, and significant fluctuations in mechanical test data.

[0057] Preferably, in the step 2, after each group of nano-scale silica is added to the mixed liquid, circular stirring and up and down stirring are combined during stirring, the circumferential stirring radius is 3-5 cm, and the up and down stirring depth covers more than 80% of the depth of the mixed liquid. During the stirring process, pause for 30-60 seconds every 2-3 minutes of stirring to prevent the heat generated by the stirring from increasing the temperature of the mixed liquid and affecting the performance of the binder. The temperature of the mixed liquid is controlled at 20℃-25℃.

[0058] Specifically, the combination of circular stirring and up-and-down stirring, with a circular stirring radius of 3-5 cm and a vertical stirring depth covering more than 80% of the mixed liquid, can disperse nano-scale silica in all directions in the mixed liquid. Taking a certain experiment as an example, when only circular stirring was used, silica gathered in the center of the container and could not be evenly dispersed, resulting in uneven texture of the final stick-like solid material. The temperature is controlled at 20℃-25℃ during the stirring pause because excessively high temperature will change the physical and chemical properties of the mixed liquid and silica, affecting the adsorption effect. For example, when stirring in a high-temperature environment, the adsorption effect of silica on the mixed oil is weakened, the bonding strength of the prepared binder decreases, and the strength of the soft soil-like material configured with it is insufficient. By standardizing the stirring method and temperature control, it can be ensured that silica is in full contact with the mixed oil, forming a stable binder, laying the foundation for subsequent material configuration.

[0059] Preferably, in the step three, before pouring the molten quartz sand into the container, the container is cleaned and dried, and there are no impurities and moisture in the container. When the binder is crushed, the particle size of the binder fragments is controlled to be 2-5 mm. When mixing, first stir at a low speed for 3-5 minutes, the stirring speed is 100-150 rpm, so that the binder is initially dispersed in the quartz sand, and then stir at a high speed for 5-8 minutes, the stirring speed is 300-400 rpm, to ensure uniform mixing.

[0060] Specifically, cleaning and drying the container is necessary to prevent interference from impurities and moisture. Moisture can cause quartz sand to clump, and impurities can alter the material's composition and properties. For example, residual dust in the container can mix with the material, leading to variations in the density and strength of similar soft clay materials. Drying fused quartz sand at a temperature of 105°C-110°C for at least 2 hours thoroughly removes moisture and ensures the sand is dry. Crushing the binder into 2-5 mm fragments facilitates thorough mixing with the sand. Excessively large fragments result in uneven mixing, while smaller fragments can easily fly and cause losses. Stirring should be performed at a low speed followed by a high speed (100-150 rpm) to initially disperse the binder, and then at a high speed (300-400 rpm) to evenly coat the sand. If mixing is performed directly at high speed, rather than at a low speed followed by a high speed, the binder may clump within the sand, resulting in significant strength variation. Only after re-stirring can the performance meet the specified standards.

[0061] Preferably, in the fourth step, a layer of release agent is pre-applied to the inside of the glass box. The release agent is a silicone release agent with a coating thickness of 0.1-0.2 mm. When filling the mixture, a layered filling method is adopted. The thickness of each layer is 3-5 cm. After each layer is filled, a flat vibrator is used to slightly vibrate the outside of the glass box. The vibration time is 1-2 minutes and the vibration frequency is 30-40 Hz to eliminate some bubbles, but avoid excessive vibration that affects the material structure.

[0062] Specifically, applying 0.1-0.2 mm silicone release agent to the glass box can form an isolation layer between the material and the glass box, making demolding easier. If the release agent is applied too thinly, the material will easily stick to the glass box; if it is applied too thickly, it will affect the surface flatness and dimensional accuracy of the material. Fill in layers of 3-5 cm each and vibrate slightly. Layering can make the material density uniform, and vibration can expel bubbles but the intensity needs to be controlled. For example, when making a large-scale soft soil-like material model, filling without layers will result in high density at the bottom and low density at the top, affecting the overall performance; excessive vibration will destroy the material structure, increase the porosity and reduce the strength. In actual engineering simulation experiments, standardized model filling operations can ensure that the manufactured soft soil-like material is closer to the real soft soil in structure and performance, thereby improving the accuracy of the experiment.

[0063] Preferably, in step five, the vacuum extraction equipment adopts a rotary vane vacuum pump, the ultimate vacuum degree of the vacuum pump reaches below -0.1 MPa, and the exhaust pipe adopts a transparent plastic tube with an inner diameter of 8-10 mm to ensure observation of the bubble discharge during the exhaust process. During the first exhaust for 1 hour, the test piece in the glass box is slightly shaken every 15-20 minutes to make it easier to discharge the bubbles; during the second exhaust for 2 hours, it is shaken every 30-40 minutes.

[0064] Specifically, a rotary vane vacuum pump with an ultimate vacuum degree of less than -0.1MPa and a transparent plastic tube with an inner diameter of 8-10mm is selected to ensure the efficiency of air extraction and to observe the discharge of bubbles. In a certain experiment, equipment with insufficient vacuum was used, and a large number of bubbles remained inside the material after air extraction, affecting the saturation effect. Shaking the specimen regularly during the air extraction process, every 15-20 minutes for the first air extraction and every 30-40 minutes for the second time, can promote the discharge of bubbles. If not shaken, bubbles may adhere to the pores of the material and be difficult to discharge. For example, in a gas extraction experiment, the specimen was not shaken, and a permeability test was performed after the material was saturated. The permeability was much lower than expected. Accurate results were obtained only after re-extraction and shaking as required. Standardized gas extraction and saturation operations can ensure that similar materials to soft soil are fully saturated, making material performance test data more reliable.

[0065] Preferably, in step six, the cover plate is made of a plexiglass plate with a thickness of 5-8 mm, and the area of ​​the cover plate is 20%-30% larger than the area of ​​the sample. When squeezing the sample, pressure is applied by evenly placing weights on the cover plate. The total mass of the weights is adjusted according to the size of the sample, generally so that the pressure on the sample reaches 0.05-0.1 MPa. When using a syringe to absorb excess upper liquid, the inner diameter of the syringe is 1-2 mm, and the absorption process is carried out slowly to avoid disturbing the sample surface.

[0066] Specifically, the plexiglass cover is 5-8 mm thick and has an area 20%-30% larger than the sample. Weights are evenly placed to compress the sample at 0.05-0.1 MPa, which can make the sample dense and discharge excess liquid. If the cover is too thin or the pressure of the weights is insufficient, the sample cannot be fully dense; excessive pressure will damage the sample structure. For example, during the preparation of a sample, excessive pressure caused the surface of the sample to crack, making it unusable for subsequent experiments. A 1-2 mm inner diameter needle slowly absorbs the liquid to avoid disturbing the sample surface. In a certain operation, a large inner diameter needle was used for rapid absorption, and the sample surface was sucked up, damaging the structure. Correct sample sampling operations can obtain complete, stable transparent cemented soil samples that meet experimental analysis requirements.

[0067] Preferably, in step seven, when adjusting the particle size of quartz sand, if the gravity γ is increased, quartz sand with a particle size range of 5.0-8.0 mm is preferably used; if the gravity γ is reduced, quartz sand with a particle size range of 0.2-0.5 mm is preferably used. When adjusting the glue-stone ratio, it is achieved by accurately weighing to increase or decrease the mass of nano-scale silica, and the adjustment accuracy is controlled within ±0.1g.

[0068] Specifically, the density is changed by adjusting the particle size of quartz sand. A particle size of 5.0-8.0 mm is used to increase the density, while a particle size of 0.2-0.5 mm is used to reduce the density. This is based on the difference in bulk density of quartz sand of different particle sizes. For example, when simulating deep-sea soft soil, the density needs to be reduced. By using quartz sand with a particle size of 0.2-0.5 mm, the density of the material is successfully made to meet the requirements. The glue-stone ratio is adjusted to control the internal friction angle, cohesion and deformation modulus. Precise weighing of nano-sized silica with an accuracy of ±0.1 g can achieve precise proportioning. For example, in a certain engineering experiment, the cohesion of the material needs to be improved. By increasing the mass of silica and increasing the glue-stone ratio, the cohesion is increased from the initial value to the target value, and the deformation modulus and internal friction angle also vary within a reasonable range, meeting the needs of engineering simulation.

[0069] Preferably, during the entire configuration process, all measuring instruments used, including balances, measuring cylinders, and volumetric flasks, are calibrated before use, and the calibration error is controlled within ±50% of the allowable error range. All operating processes are carried out in a clean, well-ventilated environment, and the ambient humidity is controlled at 40%-60% to avoid environmental factors affecting material properties.

[0070] Specifically, the calibration error of the measuring instrument is controlled within the allowable error of ±50%, which can ensure the accuracy of the measurement data. If the balance is not calibrated accurately, there will be deviations in the mass of the weighed quartz sand and white carbon black, which will lead to incorrect material ratios and affect performance. The operating environment humidity is 40%-60%, clean and ventilated. Humidity affects the water absorption of the material and the performance of the binder. A clean environment prevents the mixing of impurities. When configured in a high humidity environment, the material absorbs moisture, and the weight and strength change; in a dusty environment, impurities mix in, resulting in unstable material performance. Standardized environment and measuring instrument requirements are the key to ensuring the consistency and stability of the quality of similar materials such as soft soil.

[0071] Preferably, during the configuration process, the key parameters of each operation step, such as the refractive index of the mixed oil, the stirring time of the binder, and the particle size of the quartz sand, are recorded in detail to form an operation record document, and samples of the configured transparent binder are retained, with the number of samples being no less than 3, the volume of each sample being 50-100 cubic centimeters, and the samples being kept for no less than 6 months to facilitate subsequent review and comparative analysis of the material properties.

[0072] Specifically, key parameters, such as the refractive index of the mixed oil, stirring time, and quartz sand particle size, are recorded in detail to form operational record documents for easy tracing and problem analysis. When an experimental result is abnormal, by consulting the record documents, it is discovered that insufficient stirring time caused uneven mixing of the materials. After timely adjustments, the experiment is successful. At least three samples of 50-100 cubic centimeters each are retained and stored for six months for review and comparative analysis. For example, mechanical properties tests are performed on retained samples at different times to observe changes in material properties over time, verify material stability, and provide data support for material improvement and engineering applications.

[0073] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various equivalent changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for configuring soft soil similar materials that meets the requirements of transparency and similarity, characterized in that: The following steps are involved: Step 1: Preparation of mixed oil: At room temperature of 20°C, use an Abbe refractometer to measure the refractive index of n-dodecane and 15# white oil respectively and record them; mix n-dodecane and 15# white oil in a volume ratio of 12:400, stir thoroughly and let stand, take the upper layer of impurity-free liquid, measure the refractive index of the mixed liquid with an Abbe refractometer to make it reach 1.4585, weigh and set aside; Step 2: Wetting the binder: Divide the nano-scale silica into 8-10 groups of equal mass, add each group of silica into the prepared mixture in turn, and stir with a glass rod for more than 5 minutes after each addition to obtain a solid substance similar to a glue stick; Step 3: Mixing the mixture: Pour the washed, dried and weighed fused quartz sand into a container, crush the binder obtained in step 2 and mix it thoroughly with the fused quartz sand to form a block structure; Step 4: Filling the model: Fill the mixture obtained in step 3 naturally into the glass box without pressing during the filling process; Step 5: Vacuum saturation: Prepare a mixed oil with a mass 2-3 times that of the mixed oil in step 1. First, add the same mass of oil as in step 1 into the glass box. Vacuum the test piece at a vacuum pressure of -0.1MPa for 1 hour. Then, add the remaining liquid until the liquid level just covers the solid matter. Continue to vacuum for 2 hours. Step 6: Sample collection: Use the cover plate to squeeze the sample until it can no longer be pressed, and use a needle to absorb the excess upper liquid to obtain transparent cemented soil; Step 7. Adjust the material ratio: When adjusting the density γ, give priority to adjusting the quartz sand particle size; adjust the material internal friction angle φ only by adjusting the glue-stone ratio; adjust the cohesion c by giving priority to adjusting the glue-stone ratio; the glue-stone ratio is the factor that mainly controls the deformation modulus E.

2. A method for configuring soft soil similar materials that meets the requirements of transparency and similarity according to claim 1, characterized in that: In the first step, when measuring the refractive index of n-dodecane and 15# white oil liquid, the Abbe refractometer is calibrated using a standard substance with a known refractive index. During the calibration process, the temperature is maintained at 20°C ± 0.5°C. When mixing n-dodecane and 15# white oil, the stirring speed is controlled at 200-300 rpm for 15-20 minutes. The two liquids are fully mixed and allowed to stand for no less than 12 hours.

3. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: In the step 2, after each group of nano-sized silica is added to the mixed liquid, circular stirring and up and down stirring are combined during stirring. The circular stirring radius is 3-5 cm, and the up and down stirring depth covers more than 80% of the depth of the mixed liquid. During the stirring process, there is a pause of 30-60 seconds every 2-3 minutes of stirring, and the temperature of the mixed liquid is controlled at 20°C-25°C.

4. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: In the step three, before pouring the molten quartz sand into the container, the container is cleaned and dried, and there are no impurities and moisture in the container. When crushing the binder, the particle size of the binder fragments is controlled to be 2-5 mm. When mixing, first stir at a low speed for 3-5 minutes, the stirring speed is 100-150 rpm, so that the binder is initially dispersed in the quartz sand, and then stir at a high speed for 5-8 minutes, the stirring speed is 300-400 rpm.

5. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: In the fourth step, a layer of release agent is pre-applied to the inside of the glass box. The release agent is a silicone release agent with a coating thickness of 0.1-0.2 mm. When filling the mixture, a layered filling method is adopted. The thickness of each layer is 3-5 cm. After each layer is filled, a flat vibrator is used to lightly vibrate the outside of the glass box. The vibration time is 1-2 minutes and the vibration frequency is 30-40 Hz.

6. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: In the step 5, the vacuum pumping equipment adopts a rotary vane vacuum pump, the ultimate vacuum degree of the vacuum pump reaches below -0.1 MPa, and the exhaust pipe adopts a transparent plastic tube with an inner diameter of 8-10 mm. During the first exhaust of 1 hour, the test piece in the glass box is slightly shaken every 15-20 minutes to make it easier to discharge bubbles; during the second exhaust of 2 hours, it is shaken every 30-40 minutes.

7. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: In step six, the cover plate is made of a plexiglass plate with a thickness of 5-8 mm, and the area of ​​the cover plate is 20%-30% larger than the area of ​​the sample. When squeezing the sample, pressure is applied by evenly placing weights on the cover plate. The total mass of the weights is adjusted according to the size of the sample, generally so that the pressure on the sample reaches 0.05-0.1 MPa. When using a syringe to absorb excess upper liquid, the inner diameter of the syringe is 1-2 mm.

8. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: In the step seven, when adjusting the particle size of the quartz sand, if the gravity γ is increased, quartz sand with a particle size range of 5.0-8.0 mm is preferably used; if the gravity γ is reduced, quartz sand with a particle size range of 0.2-0.5 mm is preferably used. When adjusting the glue-stone ratio, it is achieved by accurately weighing to increase or decrease the mass of nano-scale silica, and the adjustment accuracy is controlled within ±0.1g.

9. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: During the entire configuration process, all measuring instruments used, including balances, graduated cylinders, and volumetric flasks, are calibrated before use, and the calibration error is controlled within ±50% of the allowable error range. All operations are carried out in a clean, well-ventilated environment, and the ambient humidity is controlled at 40%-60%.

10. The method for configuring soft soil similar materials that meet the requirements of transparency and similarity according to claim 1, characterized in that: During the configuration process, the key parameters of each operation step, such as the refractive index of the mixed oil, the stirring time of the binder, and the particle size of the quartz sand, are recorded in detail to form an operation record document. Samples of the configured transparent binder are retained, with the number of samples retained being no less than 3, the volume of each sample being 50-100 cubic centimeters, and the samples are kept for no less than 6 months.

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