A retaining wall reinforced soil and a preparation method and application thereof

Abstract

The application belongs to the technical field of building materials, and discloses a retaining wall reinforced soil and a preparation method and application thereof.The retaining wall reinforced soil according to the application comprises 90-95% of soil material and 5-10% of cement-based natural fiber composite material in percentage by weight; the cement-based natural fiber composite material comprises cement 75-85 parts, plant fiber 7-13 parts and basalt fiber 8-12 parts in parts by weight.The retaining wall reinforced soil according to the application can ensure the stability, safety and environmental friendliness of the filled soil between the retaining wall and the wall surface, and can be applied according to specific engineering requirements and environmental conditions, and has multifunctionality and adaptability, and has important values for the improvement of engineering construction quality, the effectiveness of land use and the protection of soil resources.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a retaining wall reinforced soil, its preparation method, and its application. Background Technology

[0002] Due to the complex terrain in mountainous areas, landscape planning involves reshaping local terrain and filling or greening areas. Using reinforced soil retaining walls in fill slopes is economical, the slope surface is easy to cover with greenery later, and the environmental protection effect is good, thus meeting the landscape requirements.

[0003] In existing reinforced soil retaining wall construction, if large machinery compacts the backfill too close to the wall surface, it can cause cracking, collapse, and toppling. Therefore, manual compaction is generally used to handle backfill soil that is too close to the wall surface (usually within 1 meter). However, manual compaction is slow and the quality is difficult to guarantee. When the backfill of a reinforced soil retaining wall is not dense, various construction quality problems will occur, such as: reduced friction between the reinforcement and the filler, reduced tensile strength; voids remaining after manual compaction; and irregular settlement such as outward bulging of the retaining wall surface and misalignment between the wall surfaces due to rainwater and groundwater seepage during construction and after commissioning, resulting in an uneven surface.

[0004] Therefore, it is urgent to improve the reinforced soil of retaining walls to meet the requirements of wall stability and drainage, ensure the stability and safety of retaining walls, and increase the service life of reinforced soil retaining walls. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing and applying reinforced soil for retaining walls. To achieve the above objective, the technical solution adopted by this invention is as follows:

[0006] In a first aspect, the present invention provides a retaining wall reinforced soil, comprising, by weight percentage, 90%-95% soil material and 5%-10% cement-based natural fiber composite material;

[0007] The cement-based natural fiber composite material comprises, by weight, 75-85 parts cement, 7-13 parts plant fiber, and 8-12 parts basalt fiber.

[0008] Preferably, the weight percentage of the soil is any one or a combination of 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 95%, 94.5%, and 95%.

[0009] Preferably, the weight percentage of the cement-based natural fiber composite material is any one or a combination of 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, and 10%.

[0010] Preferably, the cement is in the range of any one or both of the following: 75 parts, 76 parts, 77 parts, 78 parts, 79 parts, 80 parts, 81 parts, 82 parts, 83 parts, 84 parts, and 85 parts.

[0011] Preferably, the amount of plant fiber is any one or a combination of 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, and 13 parts.

[0012] Preferably, the basalt fiber is in the range of any one or both of the following: 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, and 13 parts.

[0013] In a preferred embodiment of the retaining wall reinforced soil described in this invention, the soil material is cohesive soil.

[0014] As a preferred embodiment of the retaining wall reinforced soil described in this invention, the plasticity index 17 > Ip ≥ 10 and the liquidity index I of the cohesive soil is... L ≤0.5.

[0015] Preferably, the plasticity index of the cohesive soil is any one or a combination of 16, 15, 14, 13, 12, 11, and 10 parts.

[0016] In a preferred embodiment of the retaining wall reinforced soil of the present invention, the particle size of the cohesive soil is 0.5mm-2mm.

[0017] Preferably, the particle size of the cohesive soil is any one or a combination of 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, and 2 mm.

[0018] In a preferred embodiment of the retaining wall reinforced soil described in this invention, the cement is ordinary Portland cement.

[0019] In a preferred embodiment of the retaining wall reinforced soil of the present invention, the average diameter of the plant fibers is 25μm-35μm.

[0020] Preferably, the average diameter of the plant fiber is any one or a combination of 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, and 35μm.

[0021] As a preferred embodiment of the retaining wall reinforced soil of the present invention, the basalt fiber has an average diameter of 9μm-11μm and an average length of 7mm-17mm.

[0022] Preferably, the average diameter of the basalt fiber is any one or a combination of 9μm, 9.5μm, 10μm, 10.5μm, and 11μm, and the average length is any one or a combination of 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, and 17mm.

[0023] Secondly, the present invention also provides a method for preparing the above-mentioned reinforced soil for retaining walls, comprising the following steps:

[0024] (1) The soil material is dried and crushed to obtain soil powder;

[0025] (2) Take the plant fiber, basalt fiber and the obtained soil powder and treat them with high frequency vibration for 150 min-250 min; dry them to obtain fiber dry fine soil powder.

[0026] (3) Take the cement and the obtained fiber dry fine soil powder, mix them, stir, add water, and it is ready.

[0027] Preferably, in step (3), after adding water, the resulting mixture is placed in a pre-wetted container, left to stand for 24 hours, and then the mixture is taken out, additional water is added and stirred again to mix evenly.

[0028] The initial addition of water and stirring ensures full contact between the soil particles and fibers. Allowing the mixture to stand allows the fibers to further penetrate into the tiny gaps between the soil powder particles, increasing the saturation of the soil particles. Adding additional water and stirring again after standing helps fill the gaps between particles that were not fully moistened during the initial stirring, resulting in better particle dispersion and the removal of air bubbles.

[0029] As a preferred embodiment of the preparation method of the present invention, in step (3), the stirring temperature is 25℃-35℃, the speed is 5 revolutions / min-10 revolutions / min, and the time is 25min-35min.

[0030] Preferably, the stirring temperature is within the range of any one or both of 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, and 35℃; the stirring speed is within the range of any one or both of 5 revolutions / min, 6 revolutions / min, 7 revolutions / min, 8 revolutions / min, 9 revolutions / min, and 10 revolutions / min; and the stirring time is within the range of any one or both of 25min, 26min, 27min, 28min, 29min, 30min, 31min, 32min, 33min, 34min, and 35min.

[0031] Thirdly, the present invention also applies the above-mentioned reinforced soil for retaining walls in any of the following situations:

[0032] 1. Foundation treatment

[0033] ① Foundation reinforcement in narrow construction areas: In urban environments or other areas with limited space, traditional heavy machinery is not feasible for soil compaction. The retaining wall reinforced soil can be used to reinforce the foundation. For example, in the construction of basements of high-rise buildings, due to limited surrounding space, the retaining wall reinforced soil can be used to enhance the bearing capacity and stability of the soil, thereby ensuring the safety of the superstructure.

[0034] ② Soil reinforcement around underground pipelines: Mechanical compaction of the soil around underground pipelines such as water pipes or cables may damage the pipelines. In this case, the retaining wall reinforced soil can be manually compacted to ensure soil density while avoiding damage to the pipelines.

[0035] 2. Foundation construction

[0036] ① Backfilling of fertilizer trenches and soil repair between piles: In agricultural engineering, such as the construction or maintenance of fertilizer trenches, the reinforced soil of the retaining wall can serve as an effective backfill material, especially in areas with loose soil or high organic matter content. Furthermore, in pile foundation engineering, if the original soil between piles is damaged, the reinforced soil of the retaining wall can serve as a supplementary material to enhance the stability of the entire pile foundation.

[0037] ② Foundation reinforcement in soft soil areas: In soft soil areas, such as swamps or wetlands, traditional foundation treatment methods are not effective enough. The reinforced soil in the retaining wall can significantly improve the bearing capacity and stability of the soil, thus providing a solid foundation for the construction of buildings and infrastructure.

[0038] 3. Slope protection engineering

[0039] ① Highway and Railway Slope Protection: Reinforced soil retaining walls can be used to prevent slope erosion and landslides on slopes alongside highways or railways, especially in steep or unstable terrain. By applying reinforced soil layers to the slope, the soil can be effectively stabilized, the impact of rainwater erosion reduced, and a safer road environment provided.

[0040] ② Riverbank and lakeside slope protection: In slope protection projects along rivers or lakes, the reinforced soil in retaining walls can be used to enhance slope stability, especially in areas susceptible to water erosion. The reinforced soil in retaining walls not only provides physical support but also promotes ecological balance through vegetation growth, thereby enhancing landscape value.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The reinforced soil for retaining walls of this invention ensures the stability, safety, and environmental friendliness of the backfill between the retaining wall and the wall surface. It can be applied according to specific engineering needs and environmental conditions, possessing versatility and adaptability. It has significant value in improving the quality of engineering construction, the effectiveness of land use, and the protection of soil resources. Detailed Implementation

[0043] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. In the present invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0044] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0045] The raw materials used in the following embodiments and comparative examples are described below, but are not limited to these materials:

[0046] Soil material:

[0047] Clay soil 1, plasticity index Ip≥10, liquid index IL≤0.5, natural material;

[0048] Clay soil 2, plasticity index Ip≥17, liquid index IL≤0.5, natural material;

[0049] Cement-based natural fiber composite materials:

[0050] Cement, ordinary Portland cement, purchased from Xinxiang Xinxing Cement Plant;

[0051] Plant fiber 1, with an average diameter of 30μm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0052] Plant fiber 2, with an average diameter of 20μm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0053] Plant fiber 3, with an average diameter of 10μm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0054] Plant fiber 4, with an average diameter of 50μm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0055] Basalt fiber 1, with an average diameter of 10μm and an average length of 12mm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0056] Basalt fiber 2, with an average diameter of 8μm and an average length of 6mm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0057] Basalt fiber 3, with an average diameter of 12μm and an average length of 18mm, was purchased from Jiangxi Sicheng Hemp Industry Co., Ltd.

[0058] The composition of the reinforced soil for retaining walls in the examples and comparative examples is shown in Table 1.

[0059] Table 1. Components (parts by mass) of reinforced soil for retaining walls

[0060] clay soil 1 1150 1175 1125 / 1150 1150 1150 1150 1150 clay soil 2 / / / 1150 / / / / / cement 81 80 80 81 81 81 81 81 81 Plant fiber 1 10 10 11 10 / / / 10 10 Plant fiber 2 / / / / 10 / / / / Plant fiber 3 / / / / / 10 / / / Plant fiber 4 / / / / / / 10 / / Basalt fiber 1 9 10 9 9 9 9 9 / / Basalt fiber 2 / / / / / / / 9 / Basalt fiber 3 / / / / / / / / 9

[0061] The preparation methods for the reinforced soil of the retaining walls in the above embodiments and comparative examples are as follows:

[0062] (1) Place the clay in a vacuum dryer and dry it at 80°C for 60 minutes to obtain dry soil. Then, crush the dry soil on an ultrafine pulverizer with a preset particle size of 1 mm to obtain soil powder with a particle size of less than 1 mm.

[0063] (2) Plant fiber, basalt fiber and the obtained soil powder were placed in a high-frequency vibration device and subjected to high-frequency vibration treatment for 200 minutes according to the material proportions of the embodiment or comparative example; after treatment, the mixture was dried at 80°C for 30 minutes to obtain fiber dry fine soil powder.

[0064] (3) Weigh the cement according to the material proportions of the example or comparative example, then mix the cement and fiber dry fine soil powder and stir continuously for 30 minutes at a speed of 5 revolutions / min under the condition of 30°C. Then add an appropriate amount of water to mix (the amount of water added is 12% of the total mass of fiber dry fine soil powder and cement) to obtain a mixture; put the mixture into a pre-wetted container and let it stand for 24 hours.

[0065] (4) Remove the mixture and add additional water for final mixing to ensure a uniform mixture. The water added in this step should also account for 12% of the total mass of the fiber dry fine soil powder and cement to produce high-performance reinforced soil.

[0066] The reinforced soil for retaining walls prepared in the above embodiments and comparative examples was used as soil samples to test the relevant properties of each group. The specific performance testing methods are as follows:

[0067] (1) Permeability

[0068] The permeability testing method adopts the standard "Standard for Geotechnical Testing Methods" (GB / T50123-2019). Under laboratory conditions, the permeability coefficient of soil samples is determined by controlling the test environment. Laboratory test methods include constant head permeability tests and variable head permeability tests.

[0069] The test results are presented as permeability coefficients (k-values), in cm / s, which represent the amount of water passing through a unit area of ​​soil per unit time.

[0070] (2) Density and moisture content

[0071] According to the "Standard for Geotechnical Testing Methods" (GB / T50123-2019), the compaction of soil samples is determined by compaction testing.

[0072] Testing the density of reinforced soil is a crucial step in evaluating engineering quality, as density directly affects the stability and bearing capacity of reinforced soil structures. Methods for testing density include:

[0073] Soil samples should be taken without disturbing them to maintain their original state in order to assess the impact of reinforcement on soil density. The laboratory testing method is the standard compaction test. These tests determine the maximum dry density and optimum moisture content of the soil sample at different compaction energies. The soil sample is placed in a compaction mold, and compaction energy is applied according to the prescribed method to simulate field compaction conditions. After compaction, the volume and mass of the soil sample are measured and recorded, and its dry density is calculated.

[0074] The moisture content of soil samples is typically determined by the drying method, which involves drying the soil sample to constant weight at a controlled temperature and calculating the moisture content based on the change in mass. The test results for density and moisture content are analyzed to evaluate the compaction characteristics and reinforcement effect of the soil sample.

[0075] (3) Overturning resistance

[0076] The main indicator affecting overturning resistance is the soil's shear strength, which is reflected by the soil's cohesion and friction coefficient. The soil's cohesion and friction coefficient are tested mainly according to the "Standard for Geotechnical Testing Methods" (GB / T50123-2019), and are obtained through direct shear and triaxial shear tests.

[0077] (4) Deformation control

[0078] According to the "Code for Engineering Surveying" (GB50026-2020), the settlement rate of soil samples was measured using a total station. Measurement points were installed at the engineering site, and regular observations were conducted. The settlement observation results from different examples were then compared and analyzed.

[0079] The test results are shown in Table 2:

[0080] Table 2 Performance determination of reinforced soil for retaining walls

[0081]

[0082] This invention uses a specific natural cohesive soil as the base material, adding specific cement-based plant fibers and cement-based basalt fibers. The components work synergistically and are effectively bonded through mixing. This reduces the compaction energy required to achieve a certain compaction degree, improves the soil's permeability coefficient, and enhances its strength. It is speculated that this is because the fiber surface is relatively smooth and has low surface energy. Adding cement to modify the surface increases the presence of nano-SiO2 particles, effectively improving the fiber surface roughness and increasing the effective contact area between soil particles and fibers. This allows the fiber-reinforced cement-based soil to achieve a significant strength increase without requiring large compaction energies. The modification also increases the surface energy of the fibers, giving them both good hydrophilicity and hydrophobicity, enabling them to attract and release water ions and maintain high activity over a long period, thereby improving and maintaining the drainage performance of the reinforced soil retaining wall. The permeability coefficient of the reinforced soil retaining wall of this invention is 9.0 × 10⁻⁶. -5 cm / s - 1.1 × 10 -4 The density is 90%-95%, the moisture content is 8.2%-9.3%, the overturning resistance is 2.7-3.0, and the deformation control is 11.84mm-12.56mm.

[0083] Compared to Example 1, the only difference in the reinforced soil for the retaining wall of Comparative Example 1 is that the cohesive soil used has a plasticity index Ip ≥ 17, resulting in finer particles, a lower permeability coefficient, lower density, higher water content, poorer overturning resistance, and greater susceptibility to plastic deformation under external forces. The only difference in the reinforced soil for the retaining wall of Comparative Example 2 is that the plant fibers used have an average diameter of 20 μm, resulting in a higher permeability coefficient, lower density, poorer overturning resistance, weaker absorption and dispersion of externally applied tensile forces, increased tensile stress in the soil, and reduced tensile strength. The only difference in the reinforced soil for the retaining wall of Comparative Example 3 is that the plant fibers used have an average diameter of 10 μm, resulting in a higher permeability coefficient, lower density, and higher water content. The reinforced soil for the retaining wall in Comparative Example 4 differs only in that the plant fibers used have an average diameter of 50 μm, resulting in a high permeability coefficient, low density, and poor overturning resistance. This leads to difficulties in mixing and use, reducing the engineering performance of the soil. The reinforced soil for the retaining wall in Comparative Example 5 differs only in that the basalt fibers used have an average diameter of 8 μm and an average length of 6 mm, resulting in low density, high water content, poor overturning resistance, and poor soil cohesion and strength. The reinforced soil for the retaining wall in Comparative Example 6 differs only in that the basalt fibers used have an average diameter of 12 μm and an average length of 18 mm, resulting in low density, poor overturning resistance, low viscosity and plasticity, and poor resistance to deformation.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A type of reinforced soil for retaining walls, characterized in that, By weight percentage, it comprises 90%-95% soil and 5%-10% cement-based natural fiber composite materials. The cement-based natural fiber composite material, by weight, comprises 75-85 parts cement, 7-13 parts plant fiber, and 8-12 parts basalt fiber. The soil material is cohesive soil; The plasticity index of the cohesive soil is 17 > Ip ≥ 10, and the liquidity index is I. L ≤0.5; The average diameter of the plant fibers is 25μm-35μm; The basalt fibers have an average diameter of 9μm-11μm and an average length of 7mm-17mm.

2. The reinforced soil for retaining walls according to claim 1, characterized in that, The particle size of the cohesive soil is 0.5mm-2mm.

3. The reinforced soil for retaining walls according to claim 1, characterized in that, The cement is ordinary Portland cement.

4. The method for preparing reinforced soil for retaining walls according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Take the soil material, dry it, and crush it to obtain soil powder; (2) Take the plant fiber, basalt fiber and the obtained soil powder and treat them with high frequency vibration for 150 min-250 min; dry them to obtain fiber dry fine soil powder; (3) Take the cement and the obtained fiber dry fine soil powder, mix them, stir, add water, and it is ready.

5. The preparation method according to claim 4, characterized in that, In step (3), the stirring temperature is 25℃-35℃, the speed is 5 revolutions / min-10 revolutions / min, and the time is 25min-35min.

6. The application of the reinforced soil for retaining walls as described in any one of claims 1-3 in foundation construction.

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