Mine restoration soil layer structure improvement method

Abstract

The invention discloses a mine remediation soil layer structure improvement method, and relates to the field of soil layer remediation, and the method comprises the following steps: S1, preparing a soil seed unit: mixing to-be-improved mine barren surface soil with an adhesive, and printing into a hollow dodecahedron unit with the wall thickness of 5-10 mm and a closed cavity inside by using three-dimensional printing equipment; the cavity is filled with a core mixture composed of plant seeds, a water-retaining agent, a microbial agent and a slow-release fertilizer, and the surface of the unit is subjected to hydrophobization treatment to prepare soil seeds. The problems that in the prior art, an improved layer is poor in function collaboration, low in environmental adaptability and resource utilization efficiency, poor in water diversion performance, poor in water diversion performance, poor in water diversion performance and the like are solved, and the service life of the improved layer is prolonged. The seed germination microenvironment is uncontrollable, and the restoration process lacks intelligent response capability passively.

Description

Technical Field

[0001] This invention relates to the field of soil remediation, specifically a method for improving the structure of soil layers in mine remediation. Background Technology

[0002] Mining activities have severely damaged the original surface ecosystem, leading to soil infertility, compaction, loss of fertility, and deterioration of hydrological conditions, making natural vegetation recovery difficult. Therefore, systematic artificial restoration of mine-damaged areas, particularly functional improvement of soil structure, is the core and foundation of ecological reconstruction. The purpose of soil structure improvement is not only to provide a physical foundation for plant growth but also to reconstruct a microenvironment with good coordination of water, fertilizer, air, and heat to support the long-term stability and succession of the ecosystem.

[0003] Soil structure improvement techniques in mine remediation mainly include three common methods: physical improvement, chemical improvement, and biological improvement. Physical improvement often involves backfilling with topsoil, leveling and compacting, and installing gravel drainage ditches to improve the soil's physical structure. Chemical improvement involves adding organic matter, binders, water-retaining agents, or pH adjusters to the soil to enhance its fertility and water retention capacity. Biological improvement mainly relies on inoculating with microbial agents, applying organic fertilizers, and sowing plants to promote the restoration of soil ecological functions. In addition, to cope with drought conditions, methods such as laying mulch film, non-woven fabric, or spraying soil crust inhibitors are often used for moisture retention.

[0004] The existing technical solutions mentioned above still have significant shortcomings. First, most methods only improve the soil structure from a single dimension (such as water retention or fertilization), lacking functional synergy and intelligent response mechanisms between different improvement layers, making it difficult to form a stable, adaptive, and efficient "soil-water-plant" synergistic system. Second, traditional backfilling or layered laying structures are relatively passive, unable to actively guide and efficiently utilize natural water resources (such as dew and condensation), and have poor adaptability to environmental fluctuations such as diurnal temperature differences and wet-dry cycles. Furthermore, seeds and soil improvement substrates are often simply mixed, resulting in weak controllability of the microenvironment for seed germination and seedling growth, and the success rate is greatly affected by the external environment. Therefore, there is an urgent need for a new method for improving the soil structure of mine remediation soil layers that can integrate multiple functions such as structural construction, intelligent water management, and precise seed germination, and has environmental responsiveness. Summary of the Invention

[0005] Based on this, the purpose of this invention is to provide a method for improving the structure of soil layers in mine restoration, so as to solve the technical problems in the prior art, such as poor functional synergy of the improved layer, low environmental adaptability and resource utilization efficiency, uncontrollable seed germination microenvironment, and passive lack of intelligent response capability in the restoration process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for improving the soil structure in mine restoration, comprising the following steps: S1, preparing "soil seed" units: mixing the barren topsoil to be improved with an adhesive, and then printing it into hollow dodecahedral units using a 3D printing device. The unit wall thickness is 5-10 mm, and a closed cavity is formed inside. A core mixture composed of plant seeds, water-retaining agent, microbial agent, and slow-release fertilizer is filled into the cavity, and the surface of the unit is hydrophobically treated to produce "soil seeds"; S2, constructing a capillary hindrance-hydroconducting synergistic layer: on the leveled mine surface, first lay a layer of graded crushed stone, and then lay a layer of bidirectional hydrophilic fabric woven from alternating hydrophobic and hydrophilic fibers on the crushed stone layer; the warp of the bidirectional hydrophilic fabric is polypropylene hydrophobic fiber, and the weft is modified nylon hydrophilic fiber, with a warp-to-weft density ratio of 1:2; S3, laying the "soil seed" unit. S1. Seed Unit Layer: Above the bidirectional water-wicking fabric, the "soil seed" units prepared in step S1 are laid in a tightly packed single layer, with the gaps between the units filled with fine-particle topsoil with a particle size of less than 2 mm; S4. Constructing a Photothermal Responsive Covering Layer: Above the "soil seed" unit layer, a photothermal responsive covering film is laid; this covering film uses biodegradable polycaprolactone as the substrate, and thermochromic microcapsules and shape memory polymer short fibers are uniformly dispersed within the film; the thermochromic microcapsules have a color-changing temperature of 25-35℃, and the color changes from dark to light; S5. Start-up and Activation: After the covering layer is installed, the first deep infiltration irrigation is performed, allowing water to migrate downwards through the bidirectional water-wicking fabric; simultaneously, the covering film absorbs heat during the day, triggering thermochromic and shape memory effects, causing the dew accumulated on the film surface to flow along the microchannels formed by the shape memory polymer short fibers to the surface of the lower "soil seed" unit.

[0007] The present invention is further configured such that, within the cavity of the “soil seed” unit described in step S1, the core mixture is encapsulated in a double-layer capsule consisting of a polylactic acid shell and an inner gelatin-sodium alginate hydrogel; the shell has multiple micropores with a pore size of 50-200 μm, and its degradation rate is slower than that of the inner hydrogel.

[0008] The present invention is further configured such that the bidirectional hydrophilic fabric in step S2 has an asymmetrical structure: on the side near the gravel layer, the coverage of hydrophilic weft yarns is greater than 70%; on the side near the "soil seed" unit layer, the coverage of hydrophobic warp yarns is greater than 60%.

[0009] The present invention is further configured such that the surface hydrophobic treatment of the “soil seed” unit in step S3 is performed by dip coating, and the coating material is a composite of rosin and silica nanoparticles, so that the static water contact angle of the unit surface reaches 120°-150°.

[0010] The present invention is further configured such that the shape memory polymer short fibers in the photothermal responsive coating film in step S4 are polyurethane-based materials, and their memory shape is helical and coiled, with the triggering temperature being consistent with the color change temperature range of the thermochromic microcapsules.

[0011] The present invention is further configured such that, in the first drip irrigation in step S5, the water used is activated water containing a specific germination inducing substance, wherein the inducing substance is a mixture of humic acid with a concentration of 5-20 ppm and potassium nitrate with a concentration of 0.1-0.5 mM.

[0012] The present invention is further configured such that the adhesive used in the three-dimensional printing in step S1 is the sintering effect of the soil itself at high temperature, and the temperature of the print head is controlled at 300-500℃, so that the surface of the soil particles melts and bonds.

[0013] The present invention is further configured such that the method includes a monitoring and feedback step: soil moisture and temperature sensors are deployed in the repair area, and when the surface soil moisture is detected to be lower than a set threshold and the temperature is higher than the trigger temperature of the shape memory polymer, the pulse spray system is automatically activated to replenish water for a short time and a small amount.

[0014] The invention is further configured such that the internal cavity volume of the "soil seed" unit accounts for 30%-50% of the total volume of the unit, and the cavity is not located at the geometric center, but is biased towards one of the faces of the unit that is expected to face upwards, forming an asymmetrical structure. The present invention is further configured such that when laying the photothermal responsive covering film in step S4, it is not laid completely flat, but rather it is made to form multiple gently sloping ridges with a height of 5-15cm, with the slope facing the sun, in order to increase the surface area and guide condensate to collect and infiltrate at specific locations.

[0015] In summary, the present invention has the following main beneficial effects: This invention achieves multiple beneficial effects by constructing a composite structure consisting of a "soil seed" unit layer, a capillary retardation-water conduction synergistic layer, and a photothermal response covering layer. First, the unitized "soil seeds" provide a protected and stable microenvironment for plant germination. Second, the asymmetric synergistic layer enables intelligent bidirectional regulation of water, optimizing soil moisture. Third, the photothermal response covering layer can actively capture and directionally transport non-traditional water sources such as dew. Finally, the synergistic function of each layer of the entire system transforms passive restoration into an intelligent restoration process that can actively adapt to environmental changes and efficiently utilize water and heat resources, significantly improving the reliability, longevity, and resource utilization efficiency of mine ecological restoration. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the method steps of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can implement the present invention. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the scope of protection of the present invention.

[0018] The method for improving the soil structure in mine remediation provided by this invention is implemented by constructing a multi-layered, functionally synergistic, and environmentally responsive intelligent system. The entire system, from bottom to top, includes: a "soil seed" unit layer with an asymmetric cavity structure formed by high-temperature sintering and printing of on-site soil; a capillary retardation-water conduction synergistic layer with an asymmetric water-conducting structure; and an intelligent photothermal responsive covering layer capable of actively capturing and distributing moisture. Each layer does not operate independently, but rather, through the combined effects of material properties, structural design, and environmental interaction, forms a complete remediation system that dynamically regulates water, heat, and nutrients, providing a precise microenvironment for plant seed germination and growth.

[0019] S1, Preparation of "Soil Seeds" Unit The barren topsoil from the mine to be improved is mixed with an adhesive and then printed into hollow dodecahedral units using 3D printing equipment. The dodecahedral structure has advantages such as good packing stability and a moderate specific surface area, which is conducive to the close arrangement of units and root interpenetration. The unit wall thickness is controlled at 5-10mm to ensure structural strength without excessively hindering moisture and gas exchange. An internal closed cavity is formed to accommodate the core mixture.

[0020] The core mixture consists of plant seeds, a water-retaining agent, microbial agents, and slow-release fertilizer. The plant seeds can be selected from suitable native species based on the climate and soil conditions of the remediation site; the water-retaining agent can be polyacrylamide or cellulose-based; the microbial agents include beneficial bacteria such as nitrogen-fixing bacteria and phosphate-solubilizing bacteria; and the slow-release fertilizer is a coated NPK compound fertilizer with a release period of 3-6 months.

[0021] In a preferred embodiment, the core mixture is encapsulated within a double-layered capsule consisting of a polylactic acid (PLA) shell and an inner gelatin-sodium alginate hydrogel. The PLA shell has multiple pre-formed micropores with a diameter of 50-200 μm, which degrade more slowly than the inner hydrogel. This structure allows for the phased release of moisture and nutrients; initially, the hydrogel provides the water needed for germination, while later, the shell gradually degrades to release fertilizer and inoculants.

[0022] The 3D printing method uses soil itself as the adhesive, resulting from sintering at high temperatures. The print head temperature is controlled between 300-500℃, causing the soil particles to melt and bond together. This method requires no external chemical adhesives, is environmentally friendly, and does not affect the soil's inherent properties.

[0023] After printing, the cell surface is hydrophobically treated. The treatment uses a dip-coating method, with the coating material being a composite of rosin and silica nanoparticles, achieving a static water contact angle of 120°-150° on the cell surface. This hydrophobic surface prevents premature cell disintegration during storage, transportation, or initial rainfall, while also guiding moisture to preferentially penetrate downwards through the cell gaps.

[0024] The internal cavity of the "soil seed" unit accounts for 30%-50% of the total volume of the unit, and the cavity is not located at the geometric center, but rather biased towards the upward-facing side of the unit, forming an asymmetrical structure. This design makes it easier for the seed to grow upward during germination, while the upward bias of the cavity facilitates the collection of condensed water inside.

[0025] S2. Constructing a capillary retardation-water conduction synergistic layer After leveling the mine surface, a layer of graded crushed stone is first laid, generally 10-20cm thick, with a particle size of 5-30mm and good gradation. This layer mainly serves to drain water, prevent waterlogging, and stabilize the foundation.

[0026] A layer of bidirectional hydrophilic fabric is laid on the gravel layer. This fabric is woven from alternating hydrophobic and hydrophilic fibers. Specifically, the warp is made of hydrophobic polypropylene fiber, and the weft is made of modified nylon hydrophilic fiber, with a warp-to-weft ratio of 1:2. This structure creates a moisture conduction gradient in the thickness direction of the fabric.

[0027] Furthermore, the bidirectional hydrophilic fabric has an asymmetrical structure: on the side near the gravel layer, the coverage of hydrophilic weft yarns is greater than 70% to enhance the adsorption of water from the lower layer and the ability to transport water upwards; on the side near the "soil seed" unit layer, the coverage of hydrophobic warp yarns is greater than 60% to suppress excessively rapid evaporation of water, while guiding water to diffuse laterally into the unit gaps.

[0028] S3, Deploy "soil seed" unit layers Above the bidirectional water-wicking fabric, the "soil seed" units prepared in step S1 are laid in a single layer in a tightly packed manner. Gaps naturally form between the units, which are filled with fine-particle topsoil with a particle size of less than 2 mm. The topsoil can be improved fertile soil; filling it increases the density between layers and provides a transitional medium for root extension after seed germination.

[0029] S4. Construct a photothermal response coating layer Above the "soil seed" unit layer, a photothermal responsive covering film is laid. This film, with a thickness of approximately 0.1-0.3 mm, uses biodegradable polycaprolactone as its substrate. Thermochromic microcapsules and shape memory polymer short fibers are uniformly dispersed within the film.

[0030] The thermochromic microcapsules have a color-changing temperature of 25-35℃, and the color changes from dark (such as dark blue or dark green) to light (such as light blue or light green). The color change can directly reflect the membrane surface temperature. The dark stage enhances heat absorption, while the light stage reflects some radiation, thus achieving a certain degree of temperature self-regulation.

[0031] The shape memory polymer short fibers are polyurethane-based materials, and their memory shape is a spiral coil. The trigger temperature is consistent with the color change temperature range of the thermochromic microcapsules (25-35℃). When the membrane surface temperature reaches the trigger temperature, the short fibers restore their spiral coil shape, forming microchannels within the membrane.

[0032] During installation, the photothermal responsive covering membrane is not laid flat, but rather formed into multiple gently sloping ridges, each 5-15 cm high, with the slope facing the sun. This structure increases the membrane surface area, improves dew condensation efficiency, and guides condensate to collect downwards along the slope, enhancing infiltration at specific locations.

[0033] S5, Startup and Activation After the covering layer is installed, the first deep irrigation is carried out. The water used is activated water containing a specific germination inducing substance, which is a mixture of humic acid at a concentration of 5-20 ppm and potassium nitrate at a concentration of 0.1-0.5 mM. This mixture can stimulate seeds to break dormancy and promote germination.

[0034] Drip irrigation allows water to migrate downwards through bidirectional water-wicking fabric, wetting the entire soil profile while activating microbial activity.

[0035] During the day, the covering membrane absorbs heat and heats up, triggering thermochromic changes and shape memory effects. Dew or condensate accumulated on the membrane surface is guided along microchannels formed by shape memory polymer short fibers, eventually dripping or wetting the surface of the underlying "soil seed" units, achieving active capture and utilization of non-traditional water sources.

[0036] In summary, this implementation method details the entire process from functional unit preparation and multi-layer structure construction to intelligent system operation. Through the deep integration of materials science, structural engineering, and ecological principles, it creates an integrated mine soil remediation solution that is self-regulating, proactively adapts to the environment, and efficiently utilizes resources, thus realizing a transformation from passive governance to proactive ecological restoration.

[0037] Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the invention and are not intended to limit it. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions, and variations to the embodiments as needed without departing from the principles and spirit of the invention, but such modifications, substitutions, and variations are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for improving the soil structure in mine restoration, characterized in that, Includes the following steps: S1. Preparation of "soil seed" units: The barren topsoil of the mine to be improved is mixed with an adhesive and then printed into hollow dodecahedral units using a 3D printing device. The unit wall thickness is 5-10mm, and a closed cavity is formed inside. The cavity is filled with a core mixture composed of plant seeds, water-retaining agent, microbial agent and slow-release fertilizer, and the surface of the unit is hydrophobic to make "soil seeds". S2. Constructing a capillary hindrance-hydroconducting synergistic layer: On the leveled mine surface, first lay a layer of graded crushed stone, and then lay a layer of bidirectional hydroconducting fabric woven from alternating hydrophobic and hydrophilic fibers on the crushed stone layer; the warp of the bidirectional hydroconducting fabric is polypropylene hydrophobic fiber, the weft is modified nylon hydrophilic fiber, and the warp-to-weft density ratio is 1:

2. S3. Laying out the "soil seed" unit layer: On top of the bidirectional water-wicking fabric, the "soil seed" units prepared in step S1 are laid out in a single layer in a tightly packed manner, and the gaps between the units are filled with fine-particle topsoil with a particle size of less than 2 mm. S4. Construct a photothermal responsive covering layer: A photothermal responsive covering film is laid on top of the "soil seed" unit layer; the covering film is based on biodegradable polycaprolactone, and thermochromic microcapsules and shape memory polymer short fibers are uniformly dispersed in the film; the thermochromic microcapsules have a color-changing temperature of 25-35℃, and the color changes from dark to light. S5. Start-up and activation: After the cover layer is installed, the first deep infiltration irrigation is carried out, allowing water to migrate downward through the bidirectional water-guiding fabric; at the same time, the cover film absorbs heat and heats up during the day to trigger thermochromic color change and shape memory effect, so that the dew accumulated on the film surface is guided to the surface of the lower "soil seed" unit along the microchannels formed by the shape memory polymer short fibers.

2. The method according to claim 1, characterized in that, In the cavity of the "soil seed" unit described in step S1, the core mixture is encapsulated in a double-layer capsule consisting of a polylactic acid shell and an inner gelatin-sodium alginate hydrogel; the shell has multiple micropores with a pore size of 50-200 μm, and its degradation rate is slower than that of the inner hydrogel.

3. The method according to claim 1, characterized in that, The bidirectional hydrophilic fabric described in step S2 has an asymmetrical structure: on the side near the gravel layer, the coverage of hydrophilic weft yarns is greater than 70%; on the side near the "soil seed" unit layer, the coverage of hydrophobic warp yarns is greater than 60%.

4. The method according to claim 1, characterized in that, The surface hydrophobic treatment of the "soil seed" unit in step S3 is carried out by dip coating. The coating material is a composite of rosin and silica nanoparticles, so that the static water contact angle of the unit surface reaches 120°-150°.

5. The method according to claim 1, characterized in that, In step S4, the shape memory polymer short fibers in the photothermal responsive coating film are polyurethane-based materials, and their memory shape is a spiral curl. The triggering temperature is consistent with the color change temperature range of the thermochromic microcapsules.

6. The method according to claim 1, characterized in that, In the first drip irrigation in step S5, the water used is activated water containing a specific germination inducing substance, which is a mixture of humic acid with a concentration of 5-20 ppm and potassium nitrate with a concentration of 0.1-0.5 mM.

7. The method according to claim 1, characterized in that, The adhesive used in the 3D printing in step S1 is the sintering effect of the soil itself at high temperature. The temperature of the print head is controlled at 300-500℃, so that the surface of the soil particles melts and bonds.

8. The method according to claim 1, characterized in that, The method also includes a monitoring and feedback step: soil moisture and temperature sensors are deployed in the remediation area. When the surface soil moisture is detected to be lower than a set threshold and the temperature is higher than the trigger temperature of the shape memory polymer, the pulse spray system is automatically activated to replenish water for a short time and a small amount.

9. The method according to claim 1, characterized in that, The internal cavity volume of the "soil seed" unit accounts for 30%-50% of the total volume of the unit, and the cavity is not located at the geometric center, but is biased towards the face of the unit that is expected to face upward, forming an asymmetrical structure.

10. The method according to claim 1, characterized in that, When laying the photothermal responsive covering film in step S4, it is not laid completely flat, but rather it is made into multiple gently sloping ridges with a height of 5-15cm, with the slope facing the sun, in order to increase the surface area and guide condensate to collect and infiltrate in specific locations.

Images