Light soil with bionic multilayer structure for water conservancy slope protection and preparation process of light soil

Abstract

The invention discloses light soil with a bionic multilayer structure for water conservancy slope protection and a preparation process of the light soil, and belongs to the field of water conservancy slope protection materials. In order to solve the problems that an existing slope protection material is poor in mechanical stability and ecological vegetation compatibility and prone to interlayer stripping, the light soil is integrally formed into a high-strength framework core layer, an ecological nutrition transition layer and an anti-scouring vegetation surface layer from inside to outside, and the volume ratio of the three layers is 5: 3: 2-6: 2: 2; the core layer contains light foam concrete, fibers and nano silicon dioxide, the transition layer contains porous ceramsite and slow release fertilizer, and the surface layer contains mixed seeds and anti-erosion fibers. During preparation, interlayer meshing is realized by vibrating and embedding the transition layer before initial setting of the core layer, and demolding is performed through standard curing. The anti-scouring flow velocity of the product is larger than or equal to 2.0 m / s, the interlayer shear strength is larger than or equal to 0.2 MPa, the three-month vegetation coverage rate is larger than or equal to 60%, mechanical protection and ecological functions are considered, and the method is environmentally friendly, economical and suitable for slope protection projects of rivers, reservoirs and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy slope protection materials, in particular to a light soil with a bionic multi-layer structure for water conservancy slope protection and a preparation process thereof, which is especially suitable for the slope protection of water conservancy projects such as river channels, reservoirs and embankments, and can realize the coordination and unity of mechanical stability and ecological vegetation growth function. BACKGROUND

[0002] Water conservancy slope protection is a key technical link to ensure the long-term safe and stable operation of various water conservancy projects. Its core design requirements include two functional dimensions: one is the mechanical protection performance, that is, effectively resisting the impact of flood, preventing slope instability and collapse; the other is the ecological restoration function, that is, promoting the healthy growth of vegetation and improving the ecological environment of water area and surrounding area. At present, the slope protection materials widely used in the industry can be divided into the following three categories: Rigid slope protection materials, such as traditional mortar stone and concrete precast block structure, have high compressive strength and good erosion resistance, and can withstand large water flow pressure. However, they have large self-weight, complex on-site construction, high foundation requirement, and poor ecological compatibility, and almost cannot provide growth space and attachment conditions for plants, which can easily cause ecological degradation and environmental fragmentation of the slope in the long term.

[0003] Flexible slope protection materials, including geogrid, ecological bag and vegetation blanket, are good in water permeability and vegetation compatibility, and can support the growth of shallow-rooted plants to some extent. However, their mechanical properties are weak, and the tensile and shear strength is limited, which can easily cause structure displacement, local tearing and even overall failure when facing high-speed water flow impact, such as resisting 50-year flood, and there are still obvious deficiencies in protection reliability and long-term stability.

[0004] Lightweight composite slope protection materials, mainly represented by foamed concrete, significantly reduce the material density by adding lightweight aggregate, and try to balance weight, strength and ecology. However, there are still some obvious limitations in the actual application of this kind of material: first, the structure design is relatively simple, mostly in single-layer or simple double-layer form, and the multi-functional collaborative system of "mechanical support-nutrient supply-erosion resistance" cannot be systematically constructed; second, the interlayer combination is simple, such as relying only on adhesion or mechanical assembly, which is easy to cause interface peeling and overall damage under repeated flood scouring; third, the ecological vegetation function is weak, lacking nutrient release mechanism and micro-habitat design for plant root development, resulting in low vegetation survival rate, poor community stability and low sustainability.

[0005] Therefore, in view of the actual needs of water conservancy projects and the trend of ecological transformation, a new type of integrated slope protection material is urgently needed, which must have high strength mechanical properties, excellent erosion resistance and long-term stable ecological vegetation function, so as to systematically solve the key bottlenecks and pain points in the existing slope protection technology. SUMMARY

[0006] In view of the defects of the existing water conservancy slope protection material, such as poor mechanical stability and ecological vegetation compatibility, easy interlayer peeling and nutrient loss, the application provides a biomimetic multi-layer structure light soil for water conservancy slope protection and a preparation process thereof. Through the three-layer synergistic structure of "high-strength core layer-ecological nutrient transition layer-erosion-resistant vegetation surface layer", the integrated function of "mechanical protection-nutrient supply-vegetation growth" is realized, which meets the comprehensive needs of water conservancy projects for slope protection materials.

[0007] To achieve the above-mentioned purposes, the application adopts the following technical solutions: The application first discloses a biomimetic multi-layer structure light soil for water conservancy slope protection, which is characterized by the integrated formation of at least three layers of functional synergistic structure from the inside to the outside: a high-strength skeleton core layer that bears more than 90% of the vertical load, an ecological nutrient transition layer that realizes water-air connection and nutrient slow release, and an erosion-resistant vegetation surface layer that has both erosion resistance and vegetation function. The high-strength skeleton core layer is composed of a light-weight foam concrete matrix with a dry density of 300-600 kg / m³, a fiber reinforcement network dispersed therein, and light-weight coarse aggregate. The ecological nutrient transition layer is composed of porous clay ceramsite with a porosity greater than 40%, organic binder and slow-release fertilizer, and has interconnected micropores inside. The erosion-resistant vegetation surface layer is formed by mixing and curing seeds, soil, high-molecular adhesive and erosion-resistant fibers. The volume ratio of the high-strength skeleton core layer, the ecological nutrient transition layer and the erosion-resistant vegetation surface layer ranges from 5:3:2 to 6:2:2, and the three layers are formed into a whole through interlayer mechanical engagement. The erosion-resistant velocity of the whole structure is not less than 2.0 m / s, and after 48 hours of continuous action under a dynamic water pressure of 15 kPa, the surface layer is not peeled off, the core layer is not cracked, and the vegetation coverage rate is not less than 60% within 3 months.

[0008] Further, in the high-strength skeleton core layer, the fibers are modified polypropylene fibers and / or basalt fibers, the fiber length is 6-18 mm, and the volume content is 0.5%-2%; the light-weight coarse aggregate is expanded shale ceramsite or waste rubber particles, and the particle size is 5-15 mm; the compressive strength of the light-weight foam concrete matrix is not less than 2.5 MPa.

[0009] Further, the high-strength skeleton core layer is further doped with hydrophilic nano-silica, the particle size of the nano-silica is 50-100 nm, and the doping amount is 1%-3% of the mass of the cement; the nano-silica and the fiber synergistically act to reduce the thickness of the core layer interface transition zone by 20%-30% and reduce the porosity by more than 15%.

[0010] Further, the lightweight coarse aggregate is a tire recycling waste rubber particle, the particle size of the rubber particle is 5-15 mm, and the doping amount reduces the elastic modulus of the core layer by 10%-20% and improves the impact resistance.

[0011] Further, in the ecological nutrition transition layer, the particle size of the porous clay ceramsite is 3-10 mm, and the water absorption rate is 25%-35%; the organic binder is a starch-based binder or a polyvinyl alcohol solution; the slow-release fertilizer is a coated compound fertilizer, and the mass of the slow-release fertilizer accounts for 2%-5% of the total mass of the transition layer, and the porous clay ceramsite forms a "adsorption-slow release" double-effect mechanism, and the nutrient release period is 6-12 months.

[0012] Further, in the anti-scouring vegetation surface layer, the high-molecular binder is a water-based epoxy resin or an acrylic emulsion, and the solid content is 5%-15%; the anti-erosion fiber is a coconut shell fiber or a jute fiber, and the fiber length is 10-30 mm; the seed is a mixed seed of tall fescue, kikuyu grass and alfalfa, and the mass ratio of the three is 2:3:1; the surface anti-scouring strength of the surface layer is not less than 1.5 MPa·m / s, the seed germination rate is not less than 80%, and after being scoured for 2 hours under a water flow speed of 2.0 m / s, the mass loss rate of the surface layer is not more than 5%.

[0013] Based on the foregoing description, the application further provides a process for preparing the lightweight soil for water conservancy slope protection with the above-mentioned biomimetic multi-layer structure, and the key lies in comprising the following steps: S1: preparing a high-strength skeleton core layer slurry: uniformly mixing cement, fly ash, water, an additive, a fiber and a lightweight coarse aggregate, adding foam prepared from a foaming agent, and low-speed stirring to obtain a core layer slurry with good fluidity; S2: preparing an ecological nutrition transition layer dry mixture: uniformly mixing porous clay ceramsite, organic binder dry powder and slow-release fertilizer; S3: preparing an anti-scouring vegetation surface layer slurry: mixing soil, seeds, anti-erosion fibers and a water solution of a high-molecular binder, and stirring into a paste; S4: forming a biomimetic multi-layer structure: in a customized mold, first injecting the core layer slurry obtained in S1 to a designed thickness; when the core layer slurry penetration resistance value is 3.5-5.0 MPa, uniformly spreading the transition layer dry mixture obtained in S2; finally, spraying or smearing the surface layer slurry obtained in S3 on the transition layer; S5: curing and demolding: the formed composite is subjected to standard curing, and is demolded after reaching a predetermined strength to obtain the lightweight soil block; the lightweight soil block has a scouring-resistant flow rate of not less than 2.0 m / s and an interlayer shear strength of not less than 0.2 MPa.

[0014] Further, in step S1, the foaming agent is a protein foaming agent or a composite surfactant foaming agent, and the dilution ratio of the foaming agent is 30-50 times; the density of the foam is 40-60 kg / m³.

[0015] Further, in step S4, when the dry mixture of the transition layer is scattered, slight vibration is applied by a vibration table, the vibration frequency is 30-50 Hz, the vibration amplitude is 0.5-1.0 mm, and the vibration time is 5-10 s, so that the dry mixture is embedded into the surface of the core layer slurry by 2-5 mm to realize mechanical engagement between the layers.

[0016] Further, in step S5, the curing condition is a temperature of 20±2℃ and a relative humidity of not less than 95%, and the curing time is not less than 7 days; after curing, the lightweight soil block has no structural damage under the action of a dynamic water pressure of 15 kPa for 48 hours.

[0017] Compared with the prior art, the present application has the following remarkable effects: (1) In terms of mechanical properties, the high-strength skeleton core layer has excellent compressive strength and reduced elastic modulus through the synergistic effect of the fiber reinforced network, lightweight coarse aggregate and nano-silica, and the impact resistance is significantly improved, the flood impact is effectively resisted, and the slope instability and collapse are prevented. The lightweight foam concrete matrix of the core layer and the fibers, coarse aggregates and the like jointly construct a stable mechanical support system, laying a solid foundation for the entire slope protection structure.

[0018] (2) In terms of ecological restoration function, the porous clay haydite, organic binder and slow-release fertilizer of the ecological nutrition transition layer form a unique "adsorption-slow release" dual-effect mechanism, providing a continuous nutrient supply for plant growth. The internal interconnected micropores realize water and gas communication, creating an excellent growth environment for plant roots, which helps to promote the healthy growth of vegetation and improve the water area and surrounding ecological environment. The design of the scour-resistant vegetation surface layer further guarantees the growth of vegetation and the stability of the slope, and the high molecular binder and the anti-erosion fiber enhance the scour resistance of the surface layer, while the high germination rate and low mass loss rate of the mixed seeds ensure the rapid growth of vegetation and the coverage of the slope surface.

[0019] (3) From the preparation process, by preparing each layer material respectively and adopting specific forming and curing steps, the integrated forming and excellent interlayer bonding of the three-layer structure are realized. The use of the vibration table makes the dry mixture of the transition layer embedded into the surface of the core layer slurry, forming mechanical engagement, enhancing the integrity and shear strength between the layers. Standard curing conditions ensure the strength and durability of the lightweight soil block, so that it maintains stable performance in long-term use.

[0020] In summary, compared with the existing slope protection materials, the present application overcomes the problems of poor ecological compatibility of rigid slope protection materials, weak mechanical properties of flexible slope protection materials, and single structure design, easy interlayer peeling and weak ecological plant growth function of lightweight composite slope protection materials. It realizes the coordination and unity of mechanical stability and ecological plant growth function, and provides an efficient, environmentally friendly and sustainable solution for the slope protection of water conservancy projects. This new type of slope protection material has broad application prospects in water conservancy projects such as river, reservoir and embankment, and is expected to promote the development and ecological transformation of slope protection technology in water conservancy projects. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below. Additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the present application. It should be understood that the following description is only used to explain the present application, and is not used to limit the present application.

[0022] The term "comprising", "including", "having", "containing", or any other variant thereof, used in this document, is intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not explicitly listed or inherent to such composition, step, method, article, or apparatus.

[0023] The lightweight soil for water conservancy slope protection provided by the application is integrally formed into at least three layers of functionally cooperative structure from inside to outside: a high-strength skeleton core layer that bears more than 90% of vertical load, an ecological nutrient transition layer that realizes water-air connection and nutrient slow release, and an anti-scouring and plant-growing surface layer that has both anti-scouring and plant-growing functions; the high-strength skeleton core layer is composed of lightweight foam concrete matrix with a dry density of 300-600 kg / m³, a fiber reinforced network dispersed therein and lightweight coarse aggregate; the ecological nutrient transition layer is composed of porous clay ceramsite with a porosity of more than 40%, organic binder and slow-release fertilizer, and has connected micropores inside; the anti-scouring and plant-growing surface layer is formed by mixing and solidifying seeds, soil, high-molecular binder and anti-erosion fibers; the volume ratio of the high-strength skeleton core layer, the ecological nutrient transition layer and the anti-scouring and plant-growing surface layer ranges from 5:3:2 to 6:2:2, and the three layers form a whole through interlayer mechanical engagement; the anti-scouring flow rate of the whole structure is not less than 2.0 m / s, and after 48 hours of continuous action under a dynamic water pressure of 15 kPa, the surface layer is not peeled off, the core layer is not cracked, and the vegetation coverage rate is not less than 60% within 3 months.

[0024] The design of the biomimetic multi-layer structure makes the lightweight soil have significant advantages in water conservancy slope protection applications. From the aspect of mechanical properties, the high-strength skeleton core layer, with its unique combination of lightweight foam concrete matrix, fiber reinforced network and lightweight coarse aggregate, not only can bear a large vertical load, but also has a certain flexibility, which can adapt to a certain degree of foundation deformation and avoid damage to the slope protection structure caused by slight foundation settlement or displacement.

[0025] The connected micropores of the ecological nutrient transition layer provide a good channel for the flow of water and air, making the water and air environment inside the slope more stable. At the same time, the slow-release fertilizer can continuously provide nutrients for the growth of vegetation, ensuring the healthy growth of vegetation for a long time. Moreover, this porous structure can also play a certain buffering role, reducing the direct impact of water flow on the high-strength skeleton core layer and prolonging the service life of the entire slope protection structure.

[0026] The addition of high-molecular binder and anti-erosion fibers to the anti-scouring and plant-growing surface layer greatly enhances the anti-scouring ability of the surface layer. When water flow impacts the slope, it can effectively resist the erosion of water flow and protect the internal structure from being damaged. The mixture of seeds and soil provides a good foundation for the growth of vegetation, and as the vegetation grows, its root system will further reinforce the slope protection structure, forming a natural ecological protection system.

[0027] In practical applications, the preparation process of this lightweight soil is relatively simple. By precisely controlling the raw material ratios and molding processes of each layer, the quality and performance of the three-layer functional synergistic structure can be ensured. Furthermore, due to its lightweight nature, it is more convenient to transport and construct, effectively reducing construction costs and difficulties. In addition, the environmental performance of this lightweight soil is also noteworthy; its raw materials are mostly common building materials and natural materials, resulting in minimal environmental impact and aligning with the concept of sustainable development.

[0028] In specific implementation, in the high-strength skeleton core layer, the fiber is modified polypropylene fiber and / or basalt fiber, with a fiber length of 6-18mm and a volume content of 0.5%-2%; the lightweight coarse aggregate is expanded shale ceramsite or waste rubber particles with a particle size of 5-15mm; the compressive strength of the lightweight foamed concrete matrix is ​​not less than 2.5MPa.

[0029] Modified polypropylene fibers possess excellent flexibility and chemical resistance, enabling them to form a relatively dense network structure within lightweight foamed concrete matrices, thus enhancing the matrix's crack resistance. Basalt fibers, on the other hand, exhibit high strength and high modulus, significantly improving the overall strength and stability of the core layer. When modified polypropylene fibers and basalt fibers are used in combination, their complementary advantages further enhance the overall performance of the high-strength skeleton core layer.

[0030] For lightweight coarse aggregates, expanded shale ceramsite has advantages such as light weight, heat insulation, and thermal insulation. Applying it to the high-strength skeleton core layer can effectively reduce the self-weight of lightweight soil while improving its thermal insulation performance. The use of waste rubber granules can not only realize the reuse of waste and reduce costs, but also give the core layer a certain elasticity and shock absorption performance, enhancing its buffering capacity against water flow impact.

[0031] As a crucial component of the core layer, the lightweight foamed concrete matrix, with a compressive strength of no less than 2.5 MPa, ensures its stability under pressure, preventing damage and guaranteeing the overall stability of the slope protection structure. During the preparation of the lightweight foamed concrete matrix, parameters such as the water-cement ratio, the amount of foaming agent, and the mixing time must be strictly controlled to ensure that its quality and performance meet the requirements.

[0032] Furthermore, in practical applications, the parameters of each component in the high-strength skeleton core layer can be appropriately adjusted according to specific engineering needs and environmental conditions. For example, in areas with high water flow velocity and strong impact, the volumetric content of fibers and the compressive strength of the lightweight foamed concrete matrix can be appropriately increased; in areas with high requirements for thermal insulation performance, the proportion of expanded shale ceramsite can be increased. Through this flexible parameter adjustment, the biomimetic multi-layer structure of lightweight soil for hydraulic slope protection can better adapt to different engineering scenarios and achieve its optimal performance.

[0033] In this embodiment, the high-strength skeleton core layer is also doped with hydrophilic nano-silica, the nano-silica having a particle size of 50-100nm and an addition amount of 1%-3% of the cement mass; the nano-silica works synergistically with the fiber to reduce the thickness of the core layer interface transition zone by 20%-30% and reduce the porosity by more than 15%.

[0034] The incorporation of this hydrophilic nano-silica further optimizes the microstructure of the high-strength core layer. On one hand, the 50-100nm nano-silica particles can fill the tiny gaps between cement particles, working together with the fibers to form a denser structural network. This allows the core layer to distribute stress more evenly when subjected to external forces, effectively reducing the generation and propagation of cracks. On the other hand, the synergistic effect of the nano-silica and fibers also improves the bonding performance between the core layer and other layers. Due to the reduced thickness and porosity of the interface transition zone, the bond between the core layer and adjacent layers is tighter, enhancing the overall integrity and stability of the entire biomimetic multi-layered lightweight soil for hydraulic slope protection.

[0035] From a long-term performance perspective, the high-strength skeleton core layer incorporating hydrophilic nano-silica exhibits superior durability. Nano-silica can prevent the intrusion of moisture and harmful ions, slow down the carbonization of cement stone and the corrosion process of reinforcing steel, thereby extending the service life of the slope protection structure. This enhanced durability is particularly important in harsh hydraulic environments, such as areas with high humidity and high salinity.

[0036] Furthermore, controlling the dosage of nano-silica to 1%-3% of the cement mass is the optimal range verified by numerous experiments and practical engineering projects. Too low a dosage will not fully realize its role in improving structural performance; too high a dosage may lead to poor flowability of the core layer, increasing construction difficulty and costs. Therefore, in the actual preparation process, it is essential to strictly adhere to this dosage range to ensure that the lightweight soil for biomimetic multi-layered hydraulic slope protection achieves optimal performance indicators.

[0037] Specifically, the lightweight coarse aggregate is recycled tire waste rubber particles with a particle size of 5-15mm. Its dosage reduces the elastic modulus of the core layer by 10%-20%, thereby improving its impact resistance.

[0038] Using recycled tire waste rubber granules as lightweight coarse aggregate not only achieves waste reuse, aligning with green environmental protection principles, but also significantly improves the performance of the core layer. These rubber granules, with a particle size controlled between 5-15mm, form a uniform distribution within the core layer, ensuring its performance stability. When the rubber granule content reduces the core layer's elastic modulus by 10%-20%, the core layer can better absorb and disperse energy upon impact, thus greatly enhancing its impact resistance. In hydraulic slope protection projects, slopes are frequently subjected to external forces such as water flow impacts and wave pounding. This excellent impact resistance effectively prevents damage to the slope protection structure from external impacts, extending its service life.

[0039] Meanwhile, the presence of rubber granules also imparts a certain degree of flexibility to the core layer. When the slope protection structure is subjected to uneven settlement or soil deformation, the core layer can better adapt to the deformation, avoiding defects such as cracks, further enhancing the reliability of the entire slope protection structure. Moreover, rubber granules possess a certain degree of corrosion resistance, resisting erosion by water and chemicals in hydraulic environments, helping to maintain the stability of the core layer's performance. In subsequent preparation processes, it is necessary to strictly control the quality and dosage of rubber granules to ensure that they can fully leverage their advantages in enhancing impact resistance and flexibility, providing strong support for the performance of lightweight soil used in biomimetic multi-layered hydraulic slope protection structures.

[0040] In practical applications, the porous clay ceramsite in the ecological nutrient transition layer has a particle size of 3-10 mm and a water absorption rate of 25%-35%; the organic binder is a starch-based binder or a polyvinyl alcohol solution; the slow-release fertilizer is a coated compound fertilizer, which accounts for 2%-5% of the total mass of the transition layer, forming an "adsorption-slow release" dual-effect mechanism with the porous clay ceramsite, with a nutrient release cycle of 6-12 months.

[0041] These porous clay ceramsite particles with specific particle size and water absorption rate provide excellent physical support and a suitable environment for water and fertilizer retention for plant growth. The 3-10mm particle size creates a suitable porous structure between the ceramsite particles, which facilitates air circulation, ensuring root respiration, while also storing a certain amount of water and nutrients. The 25%-35% water absorption rate allows it to absorb and store water during rainfall or irrigation, and release it slowly during droughts to meet the water needs of plant growth.

[0042] Starch-based binders or polyvinyl alcohol solutions, as organic binders, possess excellent bonding properties and biocompatibility. They can bind porous clay ceramsite, slow-release fertilizers, and other materials together to form a stable ecological nutrient transition layer structure. Furthermore, these organic binders can gradually degrade in the natural environment, causing no pollution to soil or plants, thus meeting ecological and environmental protection requirements.

[0043] Coated compound fertilizer, as a slow-release fertilizer, comprises 2%-5% of the total mass of the transition layer, a scientifically formulated proportion. This ratio ensures sufficient nutrients for plant growth without harming plants due to excessive fertilizer. The "adsorption-slow release" dual-effect mechanism allows nutrients in the fertilizer to be first adsorbed by porous clay ceramsite and then slowly released into the soil over time, with a nutrient release cycle of 6-12 months. This provides plants with a long-term, stable nutrient supply, reducing the workload and cost of frequent fertilization.

[0044] When laying the ecological nutrient transition layer, attention should be paid to its uniformity and flatness. Mechanical or manual laying methods can be used to ensure consistent thickness and quality. After laying, appropriate compaction is necessary to enhance the stability and load-bearing capacity of the transition layer. Simultaneously, to promote rapid plant growth and development, watering and sowing can be carried out promptly after laying the transition layer, allowing the plants to take root and grow quickly, thus fulfilling their ecological slope protection function.

[0045] Specifically, in the erosion-resistant vegetation surface layer, the polymer binder is a water-based epoxy resin or acrylic emulsion with a solid content of 5%-15%; the erosion-resistant fiber is coconut shell fiber or jute fiber with a fiber length of 10-30 mm; the seeds are a mixture of tall fescue, bermudagrass, and alfalfa with a mass ratio of 2:3:1; the surface erosion resistance of the surface layer is not less than 1.5 MPa·m / s, the seed germination rate is not less than 80%, and after being washed for 2 hours at a water flow rate of 2.0 m / s, the surface layer mass loss rate does not exceed 5%.

[0046] This unique formula for the erosion-resistant vegetation surface layer gives it excellent performance. Water-based epoxy resin or acrylic emulsion, acting as a polymer binder, not only possesses excellent adhesion, effectively binding other components together to form a stable surface layer structure, but its solid content, ranging from 5% to 15%, ensures bonding while maintaining the surface layer's air and water permeability, which is beneficial for plant root growth and water penetration.

[0047] Coconut husk fiber or jute fiber, with a length of 10-30mm, is used as an anti-erosion fiber. They are interwoven in the surface layer like a fine net, increasing the surface layer's resistance to erosion. When water flows, these fibers can disperse the impact of the water flow, reducing the loss of soil particles and thus protecting the integrity of the surface layer.

[0048] The seeds are a carefully selected and proportioned mixture of tall fescue, bermudagrass, and alfalfa in a 2:3:1 mass ratio. Tall fescue is highly adaptable and resilient, capable of growing in various environments; bermudagrass grows rapidly and can quickly cover the ground, playing a role in soil stabilization and slope protection; alfalfa has nitrogen-fixing capabilities, improving soil fertility and providing favorable soil conditions for the growth of other plants. This mixed species combination allows the erosion-resistant vegetation surface to form a stable ecosystem from the early stages of plant growth.

[0049] The surface erosion resistance is no less than 1.5 MPa·m / s, meaning it can withstand a certain intensity of water flow without being easily damaged. The seed germination rate is no less than 80%, ensuring a sufficient number of plants can grow and form vegetation cover after laying. After being eroded for 2 hours at a water flow velocity of 2.0 m / s, the mass loss rate of the surface layer is no more than 5%, further demonstrating its excellent erosion resistance. This ensures its long-term effective role in water conservancy slope protection projects, providing strong protection for the safety of water conservancy facilities and the protection of the ecological environment.

[0050] This invention also provides a process for preparing the above-mentioned biomimetic multilayer structure lightweight soil for hydraulic slope protection, characterized by comprising the following steps: S1: Preparation of high-strength skeleton core layer slurry: Cement, fly ash, water, admixtures, fibers and lightweight coarse aggregates are mixed evenly, foam made from foaming agent is added, and the mixture is stirred at low speed to obtain a core layer slurry with good fluidity; S2: Preparation of ecological nutrient transition layer dry mix: Mix porous clay ceramsite, organic binder dry powder, and slow-release fertilizer evenly; S3: Preparation of erosion-resistant vegetated surface slurry: Mix the aqueous solution of soil, seeds, erosion-resistant fibers and polymer binder, and stir into a paste; S4: Bionic multilayer structure molding: In a custom mold, first inject the core layer slurry obtained from S1 to the designed thickness; when the penetration resistance value of the core layer slurry is 3.5-5.0MPa, evenly spread the dry mixture of the transition layer obtained from S2; finally, spray or apply the surface layer slurry obtained from S3 onto the transition layer. S5: Curing and Demolding: The molded composite is cured according to standard, and demolded after reaching the predetermined strength to obtain lightweight soil blocks; the lightweight soil blocks have an erosion velocity of not less than 2.0 m / s and an interlayer shear strength of not less than 0.2 MPa.

[0051] This preparation process has significant advantages and characteristics. In step S1 of preparing the high-strength skeleton core layer slurry, the lightweight coarse aggregate used can effectively reduce the self-weight of the lightweight soil, while the addition of cement and fiber ensures the strength and toughness of the core layer. Furthermore, the foam produced by the foaming agent is evenly distributed under low-speed stirring, giving the core layer slurry good fluidity, facilitating subsequent molding operations.

[0052] The ecological nutrient transition layer dry mix prepared in step S2 consists of porous clay ceramsite with a rich pore structure, which can provide a good growth space for plant roots. The organic binder dry powder can ensure a good bond between the transition layer and the core and surface layers, while the slow-release fertilizer can continuously provide nutrients for plant growth.

[0053] The erosion-resistant vegetated surface slurry prepared in step S3 provides a basic environment for seed growth through the soil, enhances the erosion resistance of the surface layer with anti-erosion fibers, and allows the slurry to form a paste-like substance that is easy to apply and can better adhere to the transition layer.

[0054] During the biomimetic multilayer structure molding process in step S4, the penetration resistance value of the core layer slurry is strictly controlled to ensure that the dry-mixed transition layer can bond well with the core layer. The surface layer slurry is sprayed or applied onto the transition layer to form a dense multilayer structure. This structure not only improves the overall performance of the lightweight soil but also creates favorable conditions for plant growth.

[0055] After curing and demolding in step S5, the resulting lightweight soil blocks exhibit excellent performance. They withstand erosion velocities of no less than 2.0 m / s, effectively resisting water flow erosion and making them suitable for hydraulic slope protection projects. The interlayer shear strength is no less than 0.2 MPa, ensuring the stability and integrity of each layer. This biomimetic multi-layered lightweight soil for hydraulic slope protection, along with its preparation process, provides an efficient, environmentally friendly, and economical solution for slope protection construction in hydraulic engineering projects.

[0056] In specific implementation, in step S1, the foaming agent is a protein-based foaming agent or a composite surfactant-based foaming agent, and the dilution ratio of the foaming agent is 30-50 times; the density of the foam is 40-60 kg / m³.

[0057] Protein-based foaming agents offer excellent foaming performance and stability, producing uniform and fine foam that helps form a stable porous structure in lightweight soil, enhancing its insulation and permeability. Composite surfactant-based foaming agents, on the other hand, possess strong surface activity, rapidly reducing liquid surface tension and generating abundant foam. Furthermore, their formulations can be adjusted to suit different preparation conditions.

[0058] Diluting the foaming agent 30-50 times is to control the quality and quantity of foam while ensuring the foaming effect. If the dilution ratio is too low and the foaming agent concentration is too high, the foam may become too dense, increasing the density of the lightweight soil and affecting its lightweight properties. If the dilution ratio is too high and the foaming agent concentration is too low, the amount of foam produced will be insufficient or of poor quality, failing to form an ideal pore structure.

[0059] Maintaining the foam density within the range of 40-60 kg / m³ ensures that the lightweight soil possesses suitable porosity and strength. If the foam density is too low and the porosity too high, the strength of the lightweight soil will decrease, making it difficult to meet the requirements of hydraulic slope protection projects. Conversely, if the foam density is too high and the porosity too low, the weight of the lightweight soil will increase, negating its lightweight advantage and affecting its thermal insulation and air permeability properties. In practice, the foam density can be precisely controlled by adjusting the parameters of the foaming equipment, such as air pressure and flow rate, to ensure that the prepared lightweight soil meets the expected performance indicators.

[0060] In this embodiment, during step S4, when spreading the dry mix of the transition layer, a slight vibration is applied by a vibration table with a vibration frequency of 30-50Hz, an amplitude of 0.5-1.0mm, and a vibration time of 5-10s, so that the dry mix is ​​embedded 2-5mm into the surface of the core layer slurry, thereby achieving interlayer mechanical interlocking.

[0061] This slight vibration and embedding depth setting enhances the bonding force between the transition layer and the core layer, preventing interlayer separation during use. A suitable vibration frequency ensures the dry mix is ​​evenly distributed on the core layer slurry surface, while an appropriate amplitude guarantees sufficient force for the dry mix to embed into the core layer. Controlling the vibration time is also crucial; too short a time may result in insufficient embedding, while too long a time may damage the core layer slurry structure. When the dry mix is ​​embedded 2-5 mm into the core layer slurry surface, the resulting mechanical interlocking structure effectively transfers stress, improving the overall mechanical properties of the lightweight soil. During subsequent construction and use, this strong interlayer bond resists external forces such as water erosion and soil compression, ensuring the stability and durability of the lightweight soil used for hydraulic slope protection. Simultaneously, this preparation process allows the transition layer to better fulfill its buffering and transitional functions, providing more stable support for the upper structure and further enhancing the application effect of the entire biomimetic multi-layer lightweight soil structure in hydraulic slope protection projects.

[0062] In specific applications, in step S5, the curing conditions are a temperature of 20±2℃, a relative humidity of not less than 95%, and a curing time of not less than 7 days; after curing, the lightweight soil blocks are subjected to continuous action under a dynamic water pressure of 15kPa for 48 hours without structural damage.

[0063] These stringent curing conditions are key to ensuring the performance of lightweight soil blocks. Curing for at least 7 days at a temperature of 20±2℃ and a relative humidity of not less than 95% allows for sufficient chemical reactions within the lightweight soil, resulting in a more stable and dense internal structure. Lightweight soil blocks cured under this condition can withstand 15kPa dynamic water pressure for 48 hours without structural damage, a characteristic that enables them to withstand long-term erosion in hydraulic slope protection projects. In actual hydraulic engineering, water pressure and erosion are the main tests for slope protection materials; this performance of lightweight soil blocks means they can maintain good structural integrity in various hydraulic environments such as rivers and lakes. Furthermore, they effectively resist the abrasion of silt and other impurities in the water flow, extending the service life of the slope protection structure. Under different seasons and climate changes, these lightweight soil blocks can also adapt to environmental changes due to their stable performance, without experiencing a decline in structural performance due to fluctuations in temperature and humidity. At the same time, it can provide reliable protection for water conservancy slope protection when facing sudden natural disasters such as floods, reduce safety hazards caused by slope damage, and lay a solid foundation for the long-term stable operation of water conservancy projects.

[0064] To further illustrate the technical effects of the present invention, the following detailed description is provided in conjunction with specific embodiments. The materials used in the embodiments are all commercially available conventional products, and the performance testing methods refer to relevant standards for water conservancy projects (such as the "Technical Specification for Application of Geosynthetics in Water Conservancy and Hydropower Projects" SL / T225-2019 and the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T50081-2019).

[0065] Example 1 1. Material proportions (based on 1m³ of lightweight soil) High-strength skeleton core layer (60% by volume, i.e., 0.6m³): 300kg cement, 100kg fly ash, 200kg water, 6kg polycarboxylate superplasticizer (20% solid content), 2kg modified polypropylene fiber (12mm length) (1% by volume), 150kg expanded shale ceramsite (8-12mm particle size), 6kg nano silica (80nm particle size) (2% by cement mass), and foam (50kg / m³ density) made from protein-based foaming agent (40 times dilution).

[0066] Ecological nutrient transition layer (volume percentage 20%, i.e. 0.2m³): 200kg of porous clay ceramsite (particle size 5-8mm, porosity 45%, water absorption 30%), 10kg of starch-based binder dry powder, and 6kg of coated compound fertilizer (NPK=15-15-15) (2.8% of the total mass of the transition layer).

[0067] Erosion-resistant vegetation surface layer (20% by volume, i.e., 0.2m³): 300kg garden soil, 0.5kg mixed seeds (tall fescue: bermudagrass: alfalfa = 2:3:1), 3kg coconut fiber (20mm in length), 20kg water-based epoxy resin (10% solid content), and 100kg water.

[0068] 2. Preparation steps The preparation shall be carried out according to steps S1-S5 of the above technical solution, wherein: S1 stirring speed 150r / min, stirring time 4min, core layer slurry slump 200mm; S2 stirring speed 400r / min, stirring time 6min; S3 stirring speed 300r / min, dry mixing 2min, wet mixing 8min, surface slurry consistency 60mm; The S4 mold has dimensions of 500mm×300mm×150mm, core layer thickness of 90mm, transition layer thickness of 30mm, surface layer thickness of 30mm, vibration parameters of 40Hz, amplitude of 0.8mm, and vibration time of 8s. S5 requires 7 days of curing time, with a curing temperature of 20℃ and a relative humidity of 96%.

[0069] 3. Performance Test Results

[0070] Example 2 1. Material proportions (based on 1m³ of lightweight soil) High-strength skeleton core layer (volume percentage 55%, i.e. 0.55m³): 280kg cement, 120kg fly ash, 190kg water, 5.6kg polycarboxylate superplasticizer (solid content 20%), 1.8kg basalt fiber (length 10mm) (volume admixture 0.8%), 120kg recycled tire waste rubber particles (particle size 5-10mm), 5.6kg nano silica (particle size 60nm) (2% of cement mass), and foam (density 45kg / m³) made from composite surfactant foaming agent (dilution ratio 35 times).

[0071] Ecological nutrient transition layer (volume percentage 30%, i.e. 0.3m³): 280kg of porous clay ceramsite (particle size 3-6mm, porosity 42%, water absorption 28%), 30kg of polyvinyl alcohol solution (solid content 15%), and 12kg of coated compound fertilizer (NPK=14-16-15) (3.9% of the total mass of the transition layer).

[0072] Erosion-resistant vegetation surface layer (15% by volume, i.e., 0.15m³): 220kg garden soil, 0.4kg mixed seeds (tall fescue: bermudagrass: alfalfa = 2:3:1), 2.5kg jute fiber (25mm in length), 18kg acrylic emulsion (12% solid content), and 90kg water.

[0073] 2. Preparation steps Referring to the preparation steps of Example 1, the parameters were adjusted as follows: S1 stirring speed is 180 r / min, stirring time is 3.5 min, and core layer slurry slump is 190 mm; The S4 core layer is 85mm thick, the transition layer is 45mm thick, the surface layer is 20mm thick, and the vibration parameters are 35Hz, 0.6mm amplitude, and 6s vibration time. S5 requires 8 days of curing time, with a curing temperature of 21℃ and a relative humidity of 95%.

[0074] 3. Performance Test Results

[0075] Example 3 1. Material proportions (based on 1m³ of lightweight soil) High-strength skeleton core layer (50% by volume, i.e., 0.5m³): 320kg cement, 80kg fly ash, 210kg water, 6.4kg polycarboxylate superplasticizer (20% solid content), 3kg modified polypropylene fiber + basalt fiber (mass ratio 1:1, length 15mm) (volume admixture 1.5%), 160kg expanded shale ceramsite + waste rubber granules (mass ratio 2:1, particle size 10-15mm), 9.6kg nano silica (particle size 100nm) (3% of cement mass), foam (density 55kg / m³) is made from protein-based foaming agent (dilution ratio 45 times).

[0076] Ecological nutrient transition layer (volume percentage 30%, i.e. 0.3m³): 300kg of porous clay ceramsite (particle size 8-10mm, porosity 48%, water absorption 35%), 15kg of starch-based binder dry powder, and 16.5kg of coated compound fertilizer (NPK=16-14-15) (5% of the total mass of the transition layer).

[0077] Erosion-resistant vegetation surface layer (20% by volume, i.e., 0.2m³): 320kg garden soil, 0.6kg mixed seeds (tall fescue: bermudagrass: alfalfa = 2:3:1), 4kg coconut fiber + jute fiber (mass ratio 1:1, length 15mm), 25kg waterborne epoxy resin + acrylic emulsion (mass ratio 1:1, solid content 8%), and 120kg water.

[0078] 2. Preparation steps Referring to the preparation steps of Example 1, the parameters were adjusted as follows: S1 stirring speed 120r / min, stirring time 5min, core layer slurry slump 210mm; The S4 core layer is 80mm thick, the transition layer is 45mm thick, the surface layer is 25mm thick, and the vibration parameters are 45Hz, 1.0mm amplitude, and 10s vibration time. S5 requires 10 days of curing time, with a curing temperature of 19℃ and a relative humidity of 97%.

[0079] 3. Performance Test Results

[0080] Comparative Analysis of Examples The test results from the above three embodiments show that: Adjusting the fiber type, lightweight coarse aggregate type, and nano-silica content in the core layer can maintain the compressive strength of the core layer at 2.6-3.0 MPa, meeting the mechanical support requirements. Optimization of the porous ceramsite particle size and slow-release fertilizer content in the transition layer can improve seed germination rate to 82%-88% and vegetation coverage to 65%-72%. The combination of anti-erosion fibers and polymer binders in the surface layer controls the surface layer mass loss rate to 2.8%-4.1%, resulting in excellent erosion resistance. All embodiments exhibit an overall scour velocity ≥2.1 m / s, interlayer shear strength ≥0.22 MPa, and no structural damage after 48 hours of continuous action under 15 kPa hydrodynamic pressure, thus meeting the protection requirements for a 50-year flood.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A light weight soil for water conservancy slope protection of a biomimetic multi-layer structure, characterized in that, The application discloses an integrated structure for bank protection and vegetation growth, which is integrally formed by three layers from inside to outside, i.e., a high-strength skeleton core layer, an ecological nutrition transition layer and an anti-scouring and vegetation growth surface layer; the high-strength skeleton core layer is formed by a light-weight foam concrete base body with a dry density of 300-600 kg / m3, a fiber reinforced network and light-weight coarse aggregates dispersed in the base body; the ecological nutrition transition layer is formed by porous clay ceramsite with a porosity of greater than 40%, an organic binder and slow-release fertilizer, and has connected micropores inside; the anti-scouring and vegetation growth surface layer is formed by seed, soil, a high-molecular binder and anti-erosion fibers; the volume ratio of the high-strength skeleton core layer, the ecological nutrition transition layer and the anti-scouring and vegetation growth surface layer ranges from 5:3:2 to 6:2:2, and the three layers are integrally formed through interlayer mechanical engagement; the integrated structure has an anti-scouring flow rate of not less than 2.0 m / s, and after 48 hours of continuous action under a dynamic water pressure of 15 kPa, the surface layer is not peeled off, the core layer is not cracked, and the vegetation coverage rate is not less than 60% within 3 months.

2. The light weight soil for the water conservancy protection slope of the biomimetic multi-layer structure according to claim 1, characterized in that, In the high-strength skeleton core layer, the fiber is modified polypropylene fiber and / or basalt fiber, the fiber length is 6-18 mm, and the volume content is 0.5%-2%; the light-weight coarse aggregate is expanded shale ceramsite or waste rubber particles, and the particle size is 5-15 mm; and the light-weight foam concrete base body has a compressive strength of not less than 2.5 MPa.

3. The light weight soil for the water conservancy protection slope of the biomimetic multi-layer structure according to claim 2, characterized in that, The high-strength skeleton core layer further contains hydrophilic nano-silicon dioxide, the nano-silicon dioxide has a particle size of 50-100 nm, and the content is 1%-3% of the cement mass; the nano-silicon dioxide and the fiber synergistically reduce the thickness of the core layer interface transition zone by 20%-30% and reduce the porosity by more than 15%.

4. The light weight soil for water conservancy protection of the biomimetic multi-layer structure according to claim 2 or 3, characterized in that, The light-weight coarse aggregate is tire recycling waste rubber particles, the rubber particles have a particle size of 5-15 mm, and the content reduces the elastic modulus of the core layer by 10%-20% and improves the impact resistance.

5. The light weight soil for the water conservancy protection slope of the biomimetic multi-layer structure according to claim 1, characterized in that, In the ecological nutrition transition layer, the porous clay ceramsite has a particle size of 3-10 mm and a water absorption rate of 25%-35%; the organic binder is a starch-based binder or a polyvinyl alcohol solution; and the slow-release fertilizer is a coated compound fertilizer, and the mass of the slow-release fertilizer accounts for 2%-5% of the total mass of the transition layer, and the slow-release fertilizer and the porous clay ceramsite form a "adsorption-slow release" dual-effect mechanism, and the nutrient release period is 6-12 months.

6. The light weight soil for the water conservancy protection slope of the biomimetic multi-layer structure according to claim 1, characterized in that, In the anti-scouring and vegetation growth surface layer, the high-molecular binder is water-based epoxy resin or acrylate emulsion, and the solid content is 5%-15%; the anti-erosion fiber is coconut shell fiber or jute fiber, and the fiber length is 10-30 mm; the seed is a mixture of tall fescue, kikuyu grass and alfalfa, and the mass ratio of the three is 2:3:1; the surface anti-scouring strength of the surface layer is not less than 1.5 MPa·m / s, the seed germination rate is not less than 80%, and after being scoured for 2 hours under a water flow rate of 2.0 m / s, the mass loss rate of the surface layer is not more than 5%.

7. A process for the preparation of the biomimetic multilayered light soil for water protection revetment according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: S1: preparing high-strength skeleton core layer slurry: mixing cement, fly ash, water, additive, fiber and lightweight coarse aggregate uniformly, adding foam prepared by foaming agent, and stirring at low speed to obtain core layer slurry with good fluidity; S2: preparing ecological nutrition transition layer dry mixture: uniformly mixing porous clay ceramsite, organic binder dry powder and slow-release fertilizer; S3: preparing erosion-resistant vegetation surface layer slurry: mixing soil, seed, erosion-resistant fiber and aqueous solution of high molecular weight binder, and stirring into paste; S4: forming bionic multi-layer structure: in a customized mold, first injecting core layer slurry obtained in S1 to a designed thickness; when the core layer slurry has a penetration resistance value of 3.5-5.0 MPa, uniformly spreading transition layer dry mixture obtained in S2; finally, spraying or smearing surface layer slurry obtained in S3 on the transition layer; S5: curing and demolding: standard curing the formed composite, and demolding after reaching a predetermined strength to obtain lightweight soil block; the lightweight soil block has an erosion-resistant flow rate of not less than 2.0 m / s and an interlayer shear strength of not less than 0.2 MPa.

8. The process of claim 7, wherein, In step S1, the foaming agent is a protein foaming agent or a composite surfactant foaming agent, and the dilution ratio of the foaming agent is 30-50 times; the density of the foam is 40-60 kg / m³.

9. The process of claim 7, wherein, In step S4, when spreading the transition layer dry mixture, a slight vibration is applied by a vibration table, the vibration frequency is 30-50 Hz, the amplitude is 0.5-1.0 mm, and the vibration time is 5-10 s, so that the dry mixture is embedded in the surface of the core layer slurry by 2-5 mm, and mechanical engagement between layers is achieved.

10. The process of claim 7, wherein, In step S5, the curing conditions are temperature of 20±2℃, relative humidity of not less than 95%, and curing time of not less than 7 days; after curing, the lightweight soil block has no structural damage under the action of 15 kPa dynamic water pressure for 48 hours.

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