Curing material and curing method for expansive soil side slope based on solid waste material and ecological restoration method for expansive soil side slope

Abstract

The invention belongs to the technical field of expansive soil side slope restoration, and particularly relates to a solid waste material-based expansive soil side slope curing material, a curing method and an ecological restoration method for an expansive soil side slope. The swelling soil slope curing material based on the solid waste material provided by the invention comprises fly ash, carbide slag, coal gangue powder and water, the mass ratio of the fly ash to the carbide slag is (0.6-0.8): (0.2-0.4); the mass ratio of the coal gangue powder in the coal ash, the carbide slag and the coal gangue powder is 0-40%. The curing material provided by the invention has the advantages of environmental protection, relatively good durability and relatively strong engineering adaptability.

Description

Technical Field

[0001] This invention belongs to the field of expansive soil slope restoration technology, specifically relating to a solidification material and solidification method for expansive soil slopes based on solid waste materials, and an ecological restoration method for expansive soil slopes. Background Technology

[0002] Expansive soil is a special type of clay that expands when exposed to water and shrinks when dehydrated, undergoing repeated expansion and contraction deformation. During moisture changes, expansive soil is prone to significant volume deformation, leading to a decrease in soil strength and the formation and expansion of cracks, which in turn can cause a series of engineering disasters such as foundation instability, structural damage, and landslides.

[0003] Exposed expansive soil slopes face a series of ecological problems, such as a sharp decline in biodiversity and severe soil erosion due to the lack of windbreak and soil stabilization by plant roots. Simple engineering reinforcement (concrete slope protection) can no longer meet the needs of ecological vegetation restoration. Therefore, it is necessary to develop an ecological slope protection technology that has good ecological restoration effect, strong soil and water conservation, and is suitable for exposed expansive soil slopes.

[0004] Industrial solid waste contains some harmful substances that cause environmental pollution, but it is also a resource in the wrong place, playing different values ​​in different applications. At present, the utilization rate of industrial solid wastes such as fly ash, carbide slag, coal gangue, and block powder is low, and there is an urgent need to improve the utilization value of industrial solid waste through resource utilization methods.

[0005] Current materials for improving expansive soil have several shortcomings: First, their durability is questionable, as they tend to fail over time, such as alkali-activated materials, water-retaining agents, and biochar. Second, their environmental friendliness is questionable, as tires and red mud contain heavy metals, and microorganisms can disrupt the environmental microbial community. Third, they are not economically viable, with high costs associated with microbial cultivation and material manufacturing. Fourth, they have poor engineering adaptability and are difficult to construct; for example, alkali-activated materials have short setting times and require rapid on-site application; materials containing microorganisms require a sterile environment and precise control of the bacterial concentration; and the large number and complexity of materials make quality control difficult during industrial production. Summary of the Invention

[0006] The purpose of this invention is to provide a solidification material and solidification method for expansive soil slopes based on solid waste materials, as well as an ecological restoration method for expansive soil slopes. The solidification material provided by this invention has the advantages of being environmentally friendly, having good durability, and being highly adaptable to engineering projects.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a solidification material for expansive soil slopes based on solid waste materials, comprising fly ash, carbide slag, and coal gangue powder; the mass ratio of fly ash to carbide slag is (0.6-0.8):(0.2-0.4); and the mass percentage of coal gangue powder in the fly ash, carbide slag, and coal gangue powder is 0-40%.

[0009] Preferably, the mass ratio of fly ash to carbide slag is 7:3; and the mass percentage of coal gangue powder in the fly ash, carbide slag, and coal gangue powder is 20%.

[0010] This invention provides a method for solidifying expansive soil slopes, comprising two approaches:

[0011] The first method involves mixing the solidification material with the expansive soil, adding water, stirring, and then compacting and solidifying it.

[0012] The solidification material comprises 10-30% of the mass of the expansive soil; the ratio of water to the mass of the solidification material and the expansive soil is (0.65-0.95):1.

[0013] The second method involves mixing the solidifying material with water to form a slurry, which is then injected into the expansive soil through drilling and grouting for solidification; the mass ratio of water to solidifying material is (0.65-0.95):1.

[0014] During grouting, the horizontal inclination angle of the borehole is 10°-35°; the borehole distance is 1-3m.

[0015] This invention provides an ecological restoration method for expansive soil slopes, comprising the following steps:

[0016] After the slope is solidified according to the solidification method described in the above technical solution, plant substrate is sprayed onto the slope surface to form a lower matrix layer.

[0017] After the lower substrate layer has solidified, a vegetation substrate containing grass seeds is sprayed onto its surface to form the upper substrate layer.

[0018] The plant substrate comprises soil, cementing material, organic fertilizer, water-retaining material, humus, and water.

[0019] Preferably, the thickness of the lower matrix is ​​5-12 cm.

[0020] Preferably, the thickness of the upper matrix layer is 1-4 cm.

[0021] Preferably, the components of the plant substrate include soil, cementing material, organic fertilizer, water-retaining material, humus, and water;

[0022] The mass ratio of the soil, cementing material, organic fertilizer, water-retaining material, humus and water is (80-120):(4-10):(5-20):(10-20):(10-25):(70-90).

[0023] Preferably, the mass ratio of the soil, cementing material, organic fertilizer, water-retaining material and humus is 100:7:10:15:20:80.

[0024] Preferably, the cementing material is cement; the organic fertilizer is chicken manure; the water-retaining material is block powder; and the humus is soil humic acid.

[0025] Preferably, when spraying the vegetation substrate containing grass seeds, the density of the grass seeds is 5-20 g / m³. 2 .

[0026] This invention provides a solidification material for expansive soil slopes based on solid waste materials, comprising fly ash, carbide slag, and coal gangue powder; the mass ratio of fly ash to carbide slag is (0.6-0.8):(0.2-0.4); and the mass percentage of coal gangue powder in the fly ash, carbide slag, and coal gangue powder is 0-40%.

[0027] The materials used in this invention have the following advantages:

[0028] First, it is environmentally friendly and economically efficient. The materials used to solidify expansive soil are all industrial solid waste, realizing "waste treatment with waste". The raw material cost is almost zero, and there is no need for high-energy-consuming treatment, which greatly reduces costs.

[0029] Secondly, it is environmentally friendly. The materials used in this invention do not contain heavy metal pollution and are easier to adjust to the optimal pH for plant growth. No other additives are added, thus avoiding ecological risks.

[0030] Third, the materials have good durability. The materials used to solidify the expansive soil are all composed of solid waste. At the same time, the water-retaining materials in the vegetation substrate are also made of solid waste. They are not affected by ultraviolet rays or microbial degradation, and will not decompose and fail due to long-term exposure. They also have strong environmental adaptability and can maintain structural stability in alkaline environments.

[0031] Fourth, it has strong engineering adaptability, uses fewer materials, and the cementitious materials in the materials can be directly mixed and are easy to mix evenly without additional interface treatment. Only commonly used mixing equipment is needed during construction, making it particularly suitable for large-scale mechanized construction scenarios. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram illustrating the ecological restoration of slopes using the present invention.

[0034] Figure 2 This is a schematic diagram of the expansive soil slope described in Example 29. Detailed Implementation

[0035] This invention provides a solidification material for expansive soil slopes based on solid waste materials, including fly ash, carbide slag, and coal gangue powder; the mass ratio of fly ash to carbide slag is (0.6-0.8):(0.2-0.4);

[0036] The mass percentage of coal gangue powder in the fly ash, carbide slag, and coal gangue powder is 0-40%.

[0037] In one embodiment of the present invention, the solidification material includes fly ash, carbide slag, and coal gangue powder; the mass ratio of fly ash to carbide slag can be (0.6-0.8):(0.2-0.4), specifically 7:3. In another embodiment of the present invention, the mass ratio of coal gangue powder in the fly ash, carbide slag, and coal gangue powder can be 0-40%, specifically 20%.

[0038] This invention provides a method for solidifying expansive soil slopes, comprising two approaches:

[0039] The first method involves mixing the solidification material with expansive soil, adding water, stirring, and then compacting and solidifying it.

[0040] In one embodiment of the present invention, the solidification material can be 10-30% of the mass of the expansive soil, specifically 10%, 20% or 30%; in another embodiment of the present invention, the mass ratio of water to the solidification material and the expansive soil can be (0.65-0.95):1, specifically 0.8:1.

[0041] The second method involves mixing the solidifying material with water to form a slurry, which is then injected into the expansive soil slope through drilling and grouting for solidification.

[0042] In one embodiment of the present invention, the mass ratio of water to curing material can be (0.65-0.95):1, specifically 0.8:1; in another embodiment of the present invention, during grouting, the horizontal angle of the borehole inclination can be 10°-35°, specifically 20°. The borehole distance can be 1-3m, specifically 1.5m.

[0043] In this invention, when the slope is close to the ground, has a small slope, and is easy to operate, the slope surface soil is mixed with the solidification material to solidify the slope. In other cases, such as when the slope is high and difficult to operate, the slope is solidified by drilling and grouting.

[0044] This invention also provides an ecological restoration method for expansive soil slopes, comprising the following steps:

[0045] After the slope is solidified according to the solidification method described in the above technical solution, plant substrate is sprayed onto the slope surface to form a lower matrix layer.

[0046] After the lower substrate layer has solidified, a vegetation substrate containing grass seeds is sprayed onto its surface to form the upper substrate layer.

[0047] The plant substrate comprises soil, cementing material, organic fertilizer, water-retaining material, humus, and water.

[0048] Figure 1 This is a schematic diagram illustrating the ecological restoration and stabilization of slopes according to the present invention, as shown below. Figure 1 As shown: After the slope is solidified according to the solidification method described in the above technical solution, plant substrate is sprayed on the slope surface to form a lower matrix layer; after the lower matrix layer is solidified, a plant substrate containing grass seeds is sprayed on its surface to form an upper matrix layer.

[0049] After the slope is solidified according to the solidification method described above, the present invention sprays plant substrate onto the slope surface to form a lower matrix layer.

[0050] In one embodiment of the present invention, the thickness of the lower matrix layer can be 5 to 12 cm, specifically 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm or 12 cm.

[0051] In one embodiment of the present invention, the cementing material may include inorganic cementing materials and / or organic gel materials; the inorganic cementing material may include air-hardening cementing materials or hydraulic cementing materials; the air-hardening cementing material may include one or more of water glass, lime, and gypsum; the hydraulic cementing material may include cement; the cement may include silicate cement; the organic gel material may be a synthetic organic gel or a natural organic gel material; the synthetic organic gel includes asphalt and / or synthetic resin.

[0052] In one embodiment of the present invention, the water-retaining material may include one or more of the following: superabsorbent resin, mineral-based water-retaining material, bio-based material, bio-based organic material, and auxiliary material; the superabsorbent resin may include polyacrylamide and / or polycarboxylate resin; the bio-based material may include Miscanthus sinensis and / or hemp straw; the mineral-based water-retaining material may include one or more of the following: expanded clay, Akadama clay, and zeolite; the bio-based organic material may include one or more of the following: plant fiber, sawdust, and peat moss; the auxiliary material may include fly ash and / or block powder, specifically block powder.

[0053] In one embodiment of the present invention, the organic fertilizer may include one or more of livestock manure, composted industrial and food processing waste, wood ash, and sludge. In another embodiment, the livestock manure may include one or more of chicken manure, pig manure, cow manure, and sheep manure, specifically chicken manure. In yet another embodiment, the compost may include one or more of compost, fermented manure, and biogas fertilizer. The industrial and food processing waste may include one or more of distiller's grains, vinegar residue, sugar residue, mushroom residue, and mushroom bran.

[0054] In one embodiment of the present invention, the humic substance may include humic acid and / or fulvic acid. The humic acid may include one or more of soil humic acid, coal humic acid, water humic acid and bio-fermented humic acid, specifically soil humic acid. The fulvic acid may be obtained by fermenting wheat straw or rice straw.

[0055] As one embodiment of the present invention, the mass ratio of the soil, cementing material, organic fertilizer, water-retaining material, humus and water can be (80-120):(4-10):(5-20):(10-20):(10-25):(70-90), specifically 100:7:10:15:20:80.

[0056] In this invention, after the lower substrate layer has solidified, a vegetation substrate containing grass seeds is sprayed onto its surface to form the upper substrate layer.

[0057] In one embodiment of the present invention, the curing of the lower matrix layer can be natural curing.

[0058] In one embodiment of the present invention, the thickness of the upper substrate layer (i.e., the surface layer) can be (1-4) cm, specifically 1 cm, 2 cm, 3 cm, or 4 cm. In another embodiment of the present invention, the grass seeds can include one or more of crested wheatgrass, ryegrass, bermudagrass, and tall fescue, specifically crested wheatgrass or ryegrass. In another embodiment of the present invention, when spraying the seed-containing vegetation substrate, the density of the grass seeds can be (5-20) g / m³. 2 This invention utilizes plant roots to stabilize slopes, and over time, a plant community gradually forms, achieving an ecological restoration effect.

[0059] 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.

[0060] The cement used in the examples is silicate cement.

[0061] Examples 1-5

[0062] Preparation method: The curing materials of Examples 1 to 5 were mixed according to the proportions in Table 1, and water was added at a water-cement ratio of 0.8:1. The performance was then tested. The unconfined compressive strength was measured using a DYE-300S compressive strength tester in accordance with GB / T50123-2019. The flowability was measured using a flowability tester in accordance with GB / T40244-2021. The stone formation rate was determined by the linear shrinkage rate, which was expressed by measuring the change in length before and after curing. The test results are shown in Table 1.

[0063] Table 1 shows that the fluidity gradually increases with the increase of coal gangue powder content. When the coal gangue powder content is 0%, the fluidity is 240 mm; when the content increases to 40%, the fluidity increases to 285 mm. The unconfined compressive strength decreases significantly with the increase of coal gangue powder content. After 7 days of curing, the unconfined compressive strength is approximately 5.8 MPa when the coal gangue powder content is 0%, about three times higher than when the content is 40%. The stone-forming rate shows a trend of first increasing and then decreasing with the increase of coal gangue powder content. When the coal gangue powder content is adjusted from 0 to 10%, the stone-forming rate changes from 96.17% to 98.23%; when the content is further adjusted to 40%, the stone-forming rate decreases to 96.37%. The optimal coal gangue powder content is 20%.

[0064] Table 1. Performance of the cured materials in Examples 1-5 (performance tested with a water-cement ratio of 0.8).

[0065]

[0066] Examples 6-10

[0067] Table 3. Curing material slurry and performance test results for Examples 6-10

[0068]

[0069] The preparation and testing methods are the same as those in Examples 1-5.

[0070] Table 3 shows that the fluidity increases with increasing water-cement ratio. At a water-cement ratio of 0.7, the fluidity is 200 mm. With further increases in the water-cement ratio, the fluidity increases by approximately 43% at a water-cement ratio of 0.9. The increasing water-cement ratio leads to a decrease in the compressive strength of the material at different curing ages. After 7 days of curing, the unconfined compressive strength decreases from 4.2 MPa to 1.1 MPa. The stone formation rate decreases with increasing water-cement ratio, decreasing from 98.2% to 94.1%.

[0071] Examples 11-14

[0072] Table 3. Performance test results of expansive soil solidification materials after solidification in Examples 11-14.

[0073]

[0074] The mixing ratio of the solidification material is as follows: the mass ratio of coal gangue powder to (carbide slag and fly ash) is 2:8, of which the mass ratio of carbide slag to fly ash is 3:7.

[0075] The performance test results from Examples 11-14 show that with the increase of the solidification material, the compressive strength, cohesion, and internal friction angle of the expansive soil are effectively improved, while the free expansion rate of the expansive soil also decreases significantly. In summary, the solidification material demonstrates remarkable performance in solidifying expansive soil.

[0076] Examples 15-19

[0077] Table 4. Component and performance test results of the lower matrix in Examples 15-19

[0078]

[0079] As shown in Table 4, when the cement content is low, the lower substrate has strong fluidity, weak stability and erosion resistance, which is not conducive to subsequent vegetation growth and ecological restoration. When the cement content is high, the lower substrate is too hard, which is also not conducive to subsequent ecological restoration.

[0080] Examples 20-23

[0081] Table 5. Composition and performance test results of the lower matrix in Examples 20-23

[0082]

[0083]

[0084] Table 5 shows that when the content of soil humic acid is low, the pH value of the lower substrate is above 11, which significantly inhibits seed germination and plant growth. When the content of soil humic acid is ≥15 parts, the pH is <11. A lower proportion of soil humic acid can reduce interference with cement hydration reaction, which is beneficial to increasing the early strength of the substrate and can also reduce costs. However, a high amount of soil humic acid may lead to excessively rapid nitrogen release in the early stage, causing seedling scorching. In summary, a soil humic acid content of 20 parts is optimal.

[0085] Examples 24-26

[0086] Table 6. Component and performance test results of the lower matrix in Examples 22-26

[0087]

[0088] The higher the bulk density, the stronger the substrate and the greater its resistance to erosion; pores provide growth space for plants and also represent the substrate's permeability, while excessive pores result in weak water retention. Table 6 shows that the pH value in Example 26 was too high, which was detrimental to plant growth; Example 25 had a larger porosity, which was more conducive to plant root growth. Considering all factors, a block powder content of 15% was chosen.

[0089] Examples 27-28

[0090] Table 7. Composition and performance test results of the lower matrix in Examples 27-28

[0091]

[0092] High levels of chicken manure organic fertilizer can cause seedling burn and reduce the shear strength (cohesion) of the substrate. It may also lead to an increase in pH, which is detrimental to plant growth. Table 7 shows that 45 days after hydroseeding, the pH value in Example 27 was suitable, which was beneficial to plant growth, and the cohesion met the requirements for slope stability. Considering all these factors, a chicken manure content of 10 parts was selected.

[0093] Example 29

[0094] (1) The solidification material is composed of fly ash, carbide slag and coal gangue powder. The mass ratio of fly ash to carbide slag is 7:3. The mass ratio of coal gangue powder in fly ash, carbide slag and coal gangue powder is 20%.

[0095] like Figures 1-2A near-triangular expansive soil slope with a horizontal length of approximately 10m, a slope height of approximately 5m, and an included angle of approximately 30° was selected for stabilization. On the slope surface closer to the ground (vertical distance from the ground approximately 1m), the stabilizing material and expansive soil were mixed, and water was added to stir and solidify the slope. The stabilizing material accounted for 30% of the mass of the expansive soil, and the mass ratio of water to solids (stabilizing material and expansive soil) was 0.8:1. In areas with a vertical distance from the ground greater than 1m, the stabilizing material was prepared into a slurry (water-cement ratio of 0.8:1), and the slope was solidified by drilling and grouting. During operation, the boreholes were inclined at a horizontal angle of 20°, and the drilling distance was 1.5m.

[0096] The degree of solidification of the solidified slope was tested using an ultrasonic non-destructive testing instrument (HC-U81). The ultrasonic strength of the solidified slope was 110 dB, while that of the unsolidified slope was 85 dB, demonstrating that the solidified slope had fewer cracks and was more stable. The tests show that the solidification material and method provided by this invention have excellent solidification capabilities for expansive soil slopes.

[0097] After the slope is solidified, a plant substrate is sprayed onto the slope surface (the mass ratio of soil, cementitious material, organic fertilizer, water-retaining material, humus and water is 100:7:10:15:20:80, forming a lower matrix layer with a thickness of about 8cm).

[0098] The surface of the lower substrate layer was sprayed with a vegetation substrate containing crested wheatgrass seeds at a seeding density of 10 g / m². 2 This forms an upper matrix layer with a thickness of approximately 2 cm.

[0099] The invention also tested the ecological restoration effect of the slope with the upper and lower substrate layers. After 45 days of sowing, the root length of the creeping lysimachia reached 15cm and the plant height reached 33cm, showing good growth. After 45 days of sowing, the pH of the upper and lower substrate layers was 7.5, which was suitable for plant growth.

[0100] 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 solidification material for expansive soil slopes based on solid waste materials, comprising fly ash, carbide slag, and coal gangue powder; wherein the mass ratio of fly ash to carbide slag is (0.6-0.8):(0.2-0.4); and the mass percentage of coal gangue powder in the fly ash, carbide slag, and coal gangue powder is 0-40%.

2. The curing material as described in claim 1, characterized in that, The mass ratio of fly ash to carbide slag is 7:3; the mass percentage of coal gangue powder in the fly ash, carbide slag and coal gangue powder is 20%.

3. A method for consolidating expansive soil slopes, comprising two approaches: The first method involves mixing the solidification material with the expansive soil, adding water, stirring, and then compacting and solidifying it. The solidification material comprises 10-30% of the mass of the expansive soil; the ratio of water to the mass of the solidification material and the expansive soil is (0.65-0.95):

1. The second method involves mixing the solidifying material with water to form a slurry, which is then injected into the expansive soil through drilling and grouting for solidification; the mass ratio of water to solidifying material is (0.65-0.95):

1. During grouting, the horizontal inclination angle of the borehole is 10°-35°; the borehole distance is 1-3m.

4. An ecological restoration method for expansive soil slopes, comprising the following steps: After the slope is solidified according to the solidification method described in the above technical solution, plant substrate is sprayed onto the slope surface to form a lower matrix layer. After the lower substrate layer has solidified, a vegetation substrate containing grass seeds is sprayed onto its surface to form the upper substrate layer. The plant substrate comprises soil, cementing material, organic fertilizer, water-retaining material, humus, and water.

5. The ecological restoration method as described in claim 4, characterized in that, The thickness of the lower matrix is ​​5-12 cm.

6. The ecological restoration method as described in claim 4, characterized in that, The thickness of the upper matrix layer is 1-4 cm.

7. The ecological restoration method as described in claim 4, characterized in that, The components of the plant substrate include soil, cementing material, organic fertilizer, water-retaining material, humus and water; The mass ratio of the soil, cementing material, organic fertilizer, water-retaining material, humus and water is (80-120):(4-10):(5-20):(10-20):(10-25):(70-90).

8. The ecological restoration method as described in claim 4, characterized in that, The mass ratio of the soil, cementing material, organic fertilizer, water-retaining material, and humus is 100:7:10:15:20:

80.

9. The ecological restoration method as described in claim 4, characterized in that, The cementing material is cement; the organic fertilizer is chicken manure; the water-retaining material is block powder; and the humus is soil humic acid.

10. The ecological restoration method as described in claim 4, characterized in that, When spraying the vegetation substrate containing grass seeds, the density of the grass seeds is 5-20 g / m³. 2 .

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