A method of modifying attapulgite dispersion soil

Abstract

The present application belongs to the technical field of subgrade anti-seepage reinforcement, and particularly relates to a method for modifying dispersible soil with attapulgite. The present application uses attapulgite as a modifying material to perform physical and chemical synergistic modification treatment on dispersible soil. Attapulgite not only has the characteristics of large specific surface area, strong adsorption performance, excellent gelation and outstanding structural stability, but also has the advantages of low cost, environmental friendliness and easy processing and construction. The present application can effectively fill the internal pores of dispersible soil, optimize the soil particle gradation, enhance the adsorption and cementation between soil particles, significantly inhibit the dispersing and disintegrating characteristics of soil, form a dense and stable structure, and further improve the overall strength, water stability and anti-seepage performance of the soil, effectively improve the disasters such as water dispersion of dispersible soil, embankment piping, channel collapse and slope instability, so that the modified dispersible soil can maintain good mechanical properties in engineering.

Description

Technical Field

[0001] This invention belongs to the field of roadbed seepage prevention and reinforcement technology, specifically relating to a method for modifying dispersible soil with attapulgite soil. Background Technology

[0002] In the field of civil engineering, dispersible soil is a common special type of soil. Its soil particles suspend and flocculate in water, making them easily eroded and carried away by rainwater or seepage. Therefore, its easy dispersion upon contact with water, weak erosion resistance, and poor water stability pose numerous challenges to the construction of roadbeds, embankments, and slope protection projects. In terms of particle characteristics, dispersible soil particles are fine and unevenly graded, with a high clay content and weak interparticle bonding, making them prone to disintegration and dispersion upon contact with water. In terms of chemical composition, compared to other conventional soils, dispersible soil is dominated by hydrophilic minerals such as montmorillonite, with strong cation exchange capacity and extremely low organic matter content, generally less than 0.5%. It lacks natural cementing substances, making it difficult to form a stable structure. In terms of pore structure, dispersible soil has small and highly interconnected pores with a disordered distribution. Upon contact with water, the pore water pressure easily increases, further exacerbating soil dispersion and disintegration, making it difficult for modified materials to effectively adhere and distribute evenly within the pores. Therefore, compared to other conventional soil types, the modification and reinforcement of dispersed soils is more difficult.

[0003] Traditional methods for modifying dispersed soil include chemical solidification, physical compaction, and the addition of inert materials. However, these methods often suffer from problems such as short-lasting modification effects, poor environmental performance, and insufficient adaptability. Zhang Xiaofei et al. published a paper titled "The Influence of Calcium Lignosulfonate on the Hydraulic-Mechanical Properties of Dispersed Soil" (Zhang Xiaofei, Li Jiachao, Chen Xinwei, et al. Influence of Calcium Lignosulfonate on the Hydraulic-Mechanical Properties of Dispersed Soil [J]. Journal of Irrigation and Drainage Machinery Engineering, 2025, 43(2): 170-177 https: / / doi.org / 10.3969 / j.issn.1674-8530.23.0282), which discloses a method for modifying dispersed soil with calcium lignosulfonate. This method can inhibit dispersion, but when soaked in water for too long, the modified layer is easily lost, leading to a rebound in dispersion. Attapulgite can fill the pores of dispersed soil through physical adsorption and chemical cementation, optimizing the soil particle size distribution and enhancing interparticle bonding, thereby improving the soil's water stability and mechanical properties. However, because the dispersion mechanism of dispersed soil is affected by multiple coupled factors, and because the properties of attapulgite itself have natural fluctuations, it is difficult to achieve a precise match between the properties of modifiers and the intrinsic characteristics of the soil, thus making it difficult to form a universally applicable modification parameter system. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for modifying the dispersive soil with attapulgite clay. By improving the microstructure of the dispersive soil, it gradually changes from the original mosaic structure to a massive cemented structure, and the contact mode between soil particles also changes from a single point contact to a more stable surface contact, further enhancing the integrity and stability of the soil mass.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions: The present invention provides a method for modifying the dispersive soil with attapulgite clay, including the following steps: Mix the air-dried and sieved dispersive soil with attapulgite clay to obtain a mixed soil sample; Add water to the obtained mixed soil sample to the optimal water content, uniformly stir, compact and cure to obtain the modified dispersive soil.

[0006] Preferably, the dispersive soil is sieved through a 0.5 - 1 mm sieve; the dry density of the dispersive soil is 1.50 - 1.70 g / cm³.

[0007] Preferably, the particle size of the attapulgite clay is 50 - 200 nm; the specific surface area of the attapulgite clay is 150 - 300 m² / g.

[0008] Preferably, the content of attapulgite clay is 6% - 10% of the mass of the dispersive soil.

[0009] Preferably, the optimal water content is 13.5% - 14.5%.

[0010] Preferably, the rotation speed of the stirring is 200 - 300 r / min, and the stirring time is 5 - 10 min.

[0011] Preferably, the compaction of the mixed soil sample is to compact the mixed soil sample in 4 - 6 layers.

[0012] Preferably, the compaction pressure is P, 0 < P ≤ 800 kPa, the single compaction time is preferably 1 - 2 seconds, and the compaction times are preferably 36 - 60 times.

[0013] Preferably, the curing time is 1 - 5 days, and the mechanical properties of the soil body are improved by 10% - 20% after extended curing.

[0014] The application of the modified dispersive soil obtained by the above-mentioned modification method as a subgrade anti-seepage reinforcement material.

[0015] In the present invention, the attapulgite clay has the characteristics of large specific surface area, strong adsorption, good gelling property, environmental protection and harmlessness, and can form a good connection with the dispersive soil particles, effectively fill the internal pores of the dispersive soil, optimize the particle gradation of the soil body, and enhance the adsorption and cementation between soil particles. Its modification mechanism for the dispersive soil is as follows: The microstructure of unmodified dispersible soil samples exhibits a distinctly loose state, with large pore sizes between particles, primarily existing as open pores. The soil particle surfaces are smooth, with no obvious cementing material adhering to them, which is one of the key reasons for their high dispersibility, high permeability, and low strength. When attapulgite is added to the dispersible soil, its microstructure is significantly improved: the fibrous crystals of attapulgite can encapsulate and bridge the soil particles, thereby constructing a stable three-dimensional skeleton structure; the surface of the soil particles is uniformly covered by fibrous crystals, and the originally large pores are filled with fibers, further enhancing the integrity and stability of the soil.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. By limiting key parameters such as the amount of attapulgite soil, dry density, and curing time, this invention achieves precise control of the modification effect, effectively overcoming the matching difficulties caused by the large differences between the natural performance fluctuations of attapulgite soil and the intrinsic characteristics of dispersible soil, thus making the modified system more stable and controllable.

[0017] 2. Under the specific dry density conditions of the soil in this invention, attapulgite fibers can form a stable three-dimensional skeleton structure, which avoids the poor reinforcement effect caused by insufficient fiber overlap and prevents uneven mixing caused by excessive fiber agglomeration, making the soil structure more compact and uniform.

[0018] 3. By controlling the specific curing time of this invention, the adsorption and flocculation effect and fiber reinforcement effect of attapulgite soil reach a synergistic peak, and stable mechanical properties and anti-dispersion properties can be obtained within a short period of time, avoiding structural relaxation and performance degradation caused by long-term curing.

[0019] 4. This invention transforms the soil microstructure from a loose, interlocked structure to a blocky, cemented structure through parameter combinations, and changes the particle contact mode from point contact to surface contact, thereby significantly improving the soil's integrity, resistance to dispersion, and impermeability. This structural transformation is a unique synergistic effect of this technical solution, rather than the result of a single material.

[0020] 5. This invention controls the soil sample sieve aperture to be 0.5~1.0 mm, the attapulgite soil content to be 6%~10%, the moisture content to be 13.5%~14.5%, and the dry density to be 1.50~1.70 g / cm³. 3 By combining specific stirring speeds and curing conditions, effective bridging and encapsulation of soil particles by attapulgite fibrous crystals were achieved, while precisely controlling the pore structure. This ensured increased strength while maintaining reasonable pore connectivity, avoiding the increased brittleness and cracking risks caused by excessive pore filling in traditional modifiers, and achieving synergistic optimization of strength, anti-dispersion properties, impermeability, and structural toughness.

[0021] In summary, this invention uses attapulgite-modified dispersible soil, which has high stability, short curing period, and more compact and uniform soil structure, thereby improving the soil's integrity, dispersibility, and impermeability, and achieving synergistic optimization of strength, dispersibility, impermeability, and structural toughness. Attached Figure Description

[0022] Figure 1 This is a process flow diagram for preparing modified dispersible soil samples according to the present invention.

[0023] Figure 2 This is a bar chart showing the permeability coefficient of attapulgite-modified dispersible soil as a function of dry density in an embodiment of the present invention; wherein, (a) is a permeability coefficient chart of dispersible soil and attapulgite-modified dispersible soil with a curing time of t=1d and a dosage of 6%, 8%, and 10%; (b) is a permeability coefficient chart of dispersible soil and attapulgite-modified dispersible soil with a curing time of t=3d and a dosage of 6%, 8%, and 10%; and (c) is a permeability coefficient chart of dispersible soil and attapulgite-modified dispersible soil with a curing time of t=5d and a dosage of 6%, 8%, and 10%.

[0024] Figure 3 This is a bar chart showing the unconfined compressive strength of attapulgite-modified dispersible soil as a function of dry density in an embodiment of the present invention; wherein, (a) is the unconfined compressive strength chart of dispersible soil and attapulgite-modified dispersible soil with a curing time of t=1d and a dosage of 6%, 8%, and 10%; (b) is the unconfined compressive strength chart of dispersible soil and attapulgite-modified dispersible soil with a curing time of t=3d and a dosage of 6%, 8%, and 10%; and (c) is the unconfined compressive strength chart of dispersible soil and attapulgite-modified dispersible soil with a curing time of t=5d.

[0025] Figure 4 This is an XRD result analysis diagram of the attapulgite-modified dispersible soil of the present invention.

[0026] Figure 5 This is an FTIR result analysis diagram of the attapulgite-modified dispersible soil of the present invention.

[0027] Figure 6 This is a microstructure diagram of the dispersible soil of the present invention.

[0028] Figure 7 This invention relates to the microstructure of attapulgite-modified dispersible soil. Detailed Implementation

[0029] This invention provides a method for modifying dispersible soil with attapulgite, comprising the following steps: The air-dried and sieved dispersible soil was mixed with attapulgite soil to obtain a mixed soil sample; Add water to the above-mentioned mixed soil sample to the required moisture content, stir evenly, compact and form, and then cure to obtain the modified dispersive soil.

[0030] In the present invention, the specific operation method of the natural air drying is as follows: spread the original dispersive soil sample on a clean tray, control the paving thickness at 2-3 cm, place it in a ventilated and dry environment with a temperature of 20-25°C and a relative humidity of 60%-80% for natural air drying, and turn it over every 4-6 h until the soil mass no longer changes, which is regarded as the completion of air drying.

[0031] In the present invention, the sieved dispersive soil is sieved by a standard test sieve with a pore size of 0.5-1 mm. Fully sieve and collect the part under the sieve as a spare sample, and remove the coarse particles and impurities on the sieve to ensure that the soil particle gradation meets the test requirements.

[0032] In the present invention, the dry density of the dispersive soil is 1.50-1.70 g / cm³.

[0033] In the present invention, the particle size of the attapulgite is 50-200 nm; the specific surface area of the attapulgite is 150-300 m² / g.

[0034] In the present invention, the content of attapulgite is 6%-10% of the mass of the dispersive soil.

[0035] In the present invention, the required moisture content is 13.5%-14.5%.

[0036] In the present invention, the rotation speed of the stirring is 200-300 r / min, and the stirring time is 5-10 min.

[0037] In the present invention, the compaction and forming is to compact the mixed soil sample in 4-6 layers.

[0038] In the present invention, the pressure of the compaction is P, 0<P≤800 kPa, the single compaction time is 1-2 s, the compaction times of each layer are 36-60 times, and the compaction is preferably carried out in a sample preparation device.

[0039] In the present invention, after the compaction, it further includes scraping the obtained product; the equipment for the scraping treatment is a serrated scraper; the serration depth of the serrated scraper is 3-5 mm. In the present invention, scraping treatment is carried out between layers, which can ensure the uniformity of the scraping depth, effectively increase the interlayer friction, and make the layers better combined.

[0040] In the present invention, the curing environmental temperature is 20-25°C, and the relative humidity is 60%-80%.

[0041] In this invention, the curing time is 1 to 5 days (d), and the mechanical properties of the soil are improved by 10% to 20% after the curing is extended.

[0042] The modified dispersible soil obtained by the aforementioned modification method is used as a roadbed seepage prevention and reinforcement material.

[0043] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1 A method for modifying dispersible soil with attapulgite soil, the flowchart is as follows: Figure 1 This includes the following steps: The original dispersed soil sample was spread evenly in a clean tray with a thickness of 2 cm. It was then placed in a well-ventilated and dry environment with a temperature of 20℃ and a relative humidity of 60% to air dry naturally. The sample was turned over every 6 hours until the soil mass no longer changed. A vibrating sieve was used with a vibration frequency of 50 Hz and an amplitude of 8 mm to ensure that the naturally air-dried dispersed soil could pass through the 0.5 mm sieve more efficiently and evenly, effectively reducing sieve clogging and improving screening efficiency and quality. The sample was then stored for later use.

[0045] Based on a dry density of 1.50 g / cm³ 3 Weigh out the prepared dispersible soil, and add attapulgite at 6% of the total mass of the dispersible soil. The particle size of the attapulgite is 50 nm. The specific surface area of ​​the attapulgite is 300 m² / g. Mix the mixture to obtain a mixed soil sample.

[0046] Water was added to the mixed soil sample until the soil moisture content was 13.5%, and a JJ-1 electric mixer was used to mix the sample at a speed of 200 r / min for 10 min.

[0047] The sample mold used had an inner diameter of 39.1 mm and a height of 80 mm. To prevent sticking and leakage, a layer of Vaseline was applied to the inner wall of the mold before sample preparation, and a thin plastic sheet was placed underneath. According to the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), the water-mixed soil sample was placed into the mold in four layers and compacted with a pressure of 300 kPa. Each compaction lasted 1 second, and each layer was compacted 36 times. The layers were roughened using a serrated scraper with a 3 mm serration depth to obtain the sample. Before loading the sample, two layers of filter paper were placed at the bottom and one layer at the top.

[0048] After the soil sample is prepared, take it out, wrap it with plastic wrap, and place it in a constant temperature and humidity environment (temperature set at 25 ℃, relative humidity maintained at 80%) for 1 day.

[0049] Example 2 A method for modifying dispersible soil with attapulgite soil includes the following steps: The original dispersed soil sample was spread evenly in a clean tray with a thickness of 2.5 cm. It was then placed in a well-ventilated and dry environment with a temperature of 23℃ and a relative humidity of 70% to air dry naturally. The sample was turned over every 5 hours until the soil mass no longer changed. A vibrating sieve was used with a vibration frequency of 50 Hz and an amplitude of 8 mm. The air-dried dispersed soil was then passed through a 0.75 mm sieve and stored for later use.

[0050] Based on a dry density of 1.60 g / cm³ 3 Weigh out the prepared dispersible soil, and add attapulgite at 8% of the total mass of the dispersible soil. The particle size of the attapulgite is 100 nm. The specific surface area of ​​the attapulgite is 200 m² / g. Mix the mixture to obtain a mixed soil sample.

[0051] Water was added to the mixed soil sample until the soil moisture content was 14.0%, and a JJ-1 electric mixer was used to mix the sample at a speed of 150 r / min for 8 min.

[0052] The sample mold used was a sample preparation device with an inner diameter of 39.1 mm and a height of 80 mm. To prevent sticking and leakage, a layer of petroleum jelly was applied to the inner wall of the mold before sample preparation, and a thin plastic sheet was placed underneath. According to the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), the mixed soil sample with added water was placed into the mold in 5 layers and compacted with a pressure of 600 kPa. The compaction time for each layer was 1.5 seconds, and the number of compaction cycles per layer was 50. The layers were roughened using a serrated scraper with a serration depth of 4 mm to obtain the sample.

[0053] After the soil sample is prepared, it is taken out, wrapped in plastic wrap, and placed in a constant temperature and humidity environment (temperature set at 23 ℃, relative humidity maintained at 70%) for 3 days.

[0054] Example 3 A method for modifying dispersible soil with attapulgite soil includes the following steps: The original dispersed soil sample was spread evenly in a clean tray with a thickness of 3 cm. It was then placed in a well-ventilated and dry environment with a temperature of 25℃ and a relative humidity of 80% to air dry naturally. The sample was turned over every 4 hours until the soil mass no longer changed. A vibrating sieve was used with a vibration frequency of 50 Hz and an amplitude of 8 mm. The air-dried dispersed soil was then passed through a 1 mm sieve and stored for later use.

[0055] Based on a dry density of 1.70 g / cm³ 3Weigh out the prepared dispersible soil, and add attapulgite at 10% of the total mass of the dispersible soil. The particle size of the attapulgite is 200 nm. The specific surface area of ​​the attapulgite is 150 m² / g. Mix the mixture to obtain a mixed soil sample.

[0056] Water was added to the mixed soil sample until the optimum moisture content of the soil sample was 14.5%, and a JJ-1 electric mixer was used to mix the sample at a speed of 300 r / min for 5 min.

[0057] The sample mold used was a sample preparation device with an inner diameter of 39.1 mm and a height of 80 mm. To prevent sticking and leakage, a layer of petroleum jelly was applied to the inner wall of the mold before sample preparation, and a thin plastic sheet was placed underneath. According to the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), the water-mixed soil sample was placed into the mold in 6 layers and compacted with a pressure of 800 kPa. The compaction time for each layer was 2 seconds, and the number of compaction times for each layer was 60. The layers were roughened using a serrated scraper with a serration depth of 5 mm to obtain the sample.

[0058] After the soil sample is prepared, it is taken out, wrapped in plastic wrap, and placed in a constant temperature and humidity environment (temperature set at 20 ℃, relative humidity maintained at 60%) for 5 days.

[0059] Test Example 1 The permeability characteristics of the dispersible soils modified in Examples 1-3 were studied, and the results are as follows: Figure 2 As shown. According to Figure 2 As can be seen from (a) in the figure, the dry density is 1.50~1.70 g / cm³. 3 Within the range, the permeability coefficient of unmodified dispersible soil increased from 17.21 × 10⁻⁶. 5 cm / s decreased to 8.63×10 5 cm / s; as the attapulgite content increased from 6% to 10%, the permeability coefficient of the sample decreased synchronously and continuously, with a dry density of 1.70 g / cm³. 3 When the admixture dosage is 10%, the permeability coefficient is 2.87 × 10⁻⁶. 5 cm / s, a decrease of 66.86% compared to unmodified soil. According to Figure 2 As can be seen from (b) in the figure, the permeability coefficient of unmodified dispersible soil is determined by dry density = 1.50 g / cm³. 3 14.52×10 5 cm / s, reduced to a dry density of 1.70 g / cm³ 3 7.48 × 10 5cm / s; After modification, the permeability coefficient of attapulgite soil decreased significantly, and the dry density was 1.70 g / cm³. 3 When the admixture dosage is 10%, the permeability coefficient is 2.53 × 10⁻⁶. 5 cm / s, a decrease of 66.18% compared to unmodified soil. According to Figure 2 As can be seen from (c), the permeability coefficient of unmodified dispersible soil is 1.50 g / cm³. 3 11.35 × 10 5 cm / s, reduced to dry density = 1.70 g / cm³ 3 6.01×10 5 cm / s; After modification, the permeability coefficient of attapulgite soil further decreased, and the dry density was 1.70 g / cm³. 3 When the admixture dosage is 10%, the permeability coefficient is 2.29 × 10⁻⁶. 5 The dry density was reduced by 61.90% compared to unmodified soil (cm / s). In summary, at a dry density of 1.50–1.70 g / cm³, [further details are needed]. 3 Within the range of attapulgite content of 6% to 10%, the permeability coefficient of the samples decreased synchronously with the increase of dry density and content. The optimal modification conditions were attapulgite content of 10% and dry density of 1.70 g / cm³. 3 This can maximize the improvement of the impermeability of dispersed soil.

[0060] Test Example 2 The strength properties of the modified dispersible soils from Examples 1-3 were studied, and the results are as follows: Figure 3 As shown. According to Figure 3 As can be seen from (a) in the figure, the dry density is 1.50~1.70 g / cm³. 3 Within the specified range, the UCS of unmodified dispersible soil increased from 30.25 kPa to 60.12 kPa; as the attapulgite content increased from 6% to 10%, the UCS of the samples continued to increase synchronously, with a dry density of 1.70 g / cm³. 3 At a modifier content of 10%, the UCS reached 146.83 kPa, an increase of 144.23% compared to unmodified soil. According to... Figure 3 As can be seen from (b) in the figure, the UCS of unmodified dispersible soil is determined by dry density = 1.50 g / cm³. 3 At 35.67 kPa, the dry density was increased to 1.70 g / cm³. 3 The pressure was 62.35 kPa; the UCS of the modified attapulgite soil was significantly improved, and the dry density was 1.70 g / cm³. 3 At a modifier content of 10%, the UCS reached 182.47 kPa, an increase of 192.65% compared to unmodified soil. According to... Figure 3As can be seen from (c), the UCS of unmodified dispersible soil is determined by dry density = 1.50 g / cm³. 3 At a pressure of 40.18 kPa, the dry density was increased to 1.70 g / cm³. 3 The pressure was 76.29 kPa; the UCS was further improved after attapulgite soil modification, and the dry density was 1.70 g / cm³. 3 At a dosage of 10%, the UCS reached 191.56 kPa, an increase of 151.10% compared to unmodified soil. In summary, at a dry density of 1.50~1.70 g / cm³... 3 Within the range of attapulgite content (6%–10%), the UCS of the samples increased synchronously with the increase of dry density and content. The optimal modification conditions were attapulgite content of 10% and dry density of 1.70 g / cm³. 3 This can maximize the improvement of the mechanical properties of dispersed soil.

[0061] Test Example 3 XRD tests on the modified dispersible soil of Example 3 can reflect the changes in the type, content, and crystal structure of clay minerals in the modified dispersible soil. Figure 4 As shown, Figure 4 In the diagram, `calculate` (solid red line) refers to the theoretical calculated value or fitted curve, which is the theoretical diffraction pattern calculated by software based on the constructed crystal structure model. `observed` (black dots) refers to the experimentally measured value, which is the sample diffraction data actually collected by an X-ray diffractometer. `error` (green curve) refers to the residual error curve, representing the difference between the measured and calculated values. If the curve is close to the horizontal axis, it indicates high fitting accuracy. `R` refers to the residual factor, a key indicator of the degree of agreement between the fitted curve and the measured data. In the diagram, `R = 15.54%` represents the fitting error rate. `2θ` refers to the diffraction angle, the horizontal axis of the X-ray diffraction pattern, in degrees (°), reflecting the angular position of the diffracted light, corresponding to different crystal interplanar spacings. The characteristic diffraction peaks of attapulgite are located near 2θ≈6.43° and 8.38°, while those near 2θ≈31° and 40° correspond to dolomite and feldspar, respectively. The intensity of these characteristic peaks significantly increases with increasing modifier dosage, indicating that attapulgite is uniformly dispersed in the soil and exists as an independent phase. The calculated and measured curves of the samples show good fit, and the residual curves are stable. After modification with attapulgite, the characteristic peak positions of the original clay minerals such as kaolinite and illite in the soil sample did not shift significantly, indicating that the addition of the modifier did not alter the basic crystal structure of these clay minerals.

[0062] Test Example 4 FTIR tests on the modified dispersible soil of Example 3 revealed its mineral composition and chemical bond characteristics. Figure 5As shown, the modified attapulgite soil has a thickness of 3424.76 cm. -1 The corresponding OH stretching vibration showed broadened peak shape and increased intensity, indicating that water and hydroxyl groups in the interlayer of the attapulgite soil formed a hydrogen bond network with the soil particle surface. The modified attapulgite soil sample was 1627.92 cm². -1 The increased peak intensity corresponding to the HOH bending vibration of water molecules indicates a synergistic effect between the hydrophilic properties of attapulgite and the bound water in the soil. Attapulgite-modified soil, 1438.28 cm³. -1 The weakening peak intensity corresponding to the C=O stretching vibration of carbonate minerals indicates the adsorption and encapsulation effect of attapulgite on carbonate particles. Attapulgite-modified soil, 875.68 cm³. -1 The lower peaks are due to the Si-O bending vibration of silicate minerals, and the peak shape is more regular, reflecting that the mineral skeleton has a more compact structure under the action of filling and cementation.

[0063] Test Example 5 SEM tests were conducted on the modified dispersible soil from the examples. Example 3 was selected, with a curing time of 5 days and a dry density of 1.7 g / cm³. 3 The apparent morphology and pore characteristics of dispersed soil and modified soil with 10% attapulgite were analyzed under the given conditions. Figure 6 As shown in the figure, the unmodified soil sample has a loose microstructure with large interparticle pores, mainly consisting of open pores. The particle surfaces are smooth and lack obvious cementing material. Figure 7 As shown in the figure, after incorporating attapulgite, fibrous crystals encapsulate and bridge soil particles, forming a three-dimensional skeletal structure. The particle surface is covered by fibers, and the pores are filled with fibers while retaining a certain degree of connectivity. In addition, attapulgite gradually transforms the soil structure from an embedded structure to a clumpy cemented structure, and the contact mode between soil particles changes from point contact to surface contact.

[0064] Comparative Example This comparative example uses calcium lignosulfonate as a modifier, with a dosage of 2%. The remaining raw materials, dry density, curing time, and preparation process are the same as in Example 1.

[0065] Comparison and explanation Compared with the comparative examples, Examples 1-3 all have the following advantages: 1. This invention enables attapulgite to form a stable three-dimensional skeleton structure through a combination of specific dosage, dry density and curing time, achieving a synergistic effect of fiber reinforcement and adsorption flocculation, resulting in more durable and stable anti-dispersion properties; while calcium lignosulfonate relies only on surface adsorption and ion replacement, which has a single function, is easy to desorb and has poor stability.

[0066] 2. This invention transforms the soil structure from an embedded structure to a blocky cemented structure through parameter control, and changes the particle contact mode from point contact to surface contact. In contrast, calcium lignosulfonate can only achieve a single cementing effect. The mechanical properties of this invention are significantly better than those of the calcium lignosulfonate modified system.

[0067] 3. Calcium lignosulfonate tends to overfill pores, leading to increased structural brittleness. However, this invention reduces permeability while maintaining reasonable pore connectivity, avoiding the increased brittleness and cracking risk caused by excessive pore blockage by traditional modifiers, and achieving synergistic optimization of strength, anti-dispersion properties and structural toughness.

[0068] 4. This invention effectively reduces the impact of intrinsic soil differences through parameter combination, making the modified system more stable and controllable, and with a wider range of applications; while calcium lignosulfonate is greatly affected by soil composition, pH value, and pore water chemical environment, and has poor universality.

[0069] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for modifying dispersible soil with attapulgite, characterized in that, It includes the following steps: Mix the naturally air-dried and sieved dispersive soil with attapulgite clay to obtain a mixed soil sample; Add water to the mixed soil sample to the required moisture content, uniformly stir, compact and cure to obtain the modified dispersive soil.

2. The modification method according to claim 1, characterized in that, The dispersive soil is sieved through a 0.5 - 1 mm sieve; the dry density of the dispersive soil is 1.50 - 1.70 g / cm³.

3. The modification method according to claim 1, characterized in that, The particle size of the attapulgite clay is 50 - 200 nm; the specific surface area of the attapulgite clay is 150 - 300 m² / g.

4. The modification method according to claim 1, characterized in that, The dosage of the attapulgite clay is 6% - 10% of the mass of the dispersive soil.

5. The modification method according to claim 1, characterized in that, The required moisture content is 13.5% - 14.5%.

6. The modification method according to claim 1, characterized in that, The rotation speed of the stirring is 200 - 300 r / min, and the stirring time is 5 - 10 min.

7. The modification method according to claim 1, characterized in that, The compaction and molding is to compact the mixed soil sample in 4 - 6 layers by compaction.

8. The modification method according to claim 7, characterized in that, The pressure of the compaction is P, 0 < P ≤ 800 kPa. The single compaction time is preferably 1 - 2 seconds, and the single compaction number is preferably 36 - 60 times.

9. The modification method according to claim 1, characterized in that, The curing time is 1 - 5 days.

10. Application of the modified dispersive soil obtained by the modification method according to any one of claims 1 to 9 as a subgrade anti-seepage and reinforcement material.

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