Slope covering layer with enzyme-induced calcium carbonate precipitation and vegetation synergy and construction method thereof

Abstract

This application relates to the field of slope reinforcement technology in geotechnical engineering, specifically disclosing an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer and its construction method. It involves constructing a coarse-particle drainage layer and laying a geotextile filter layer. A mixed-type enzyme-induced calcium carbonate precipitation process is used, where dried sword bean powder and slag are pre-mixed evenly and then laid and compacted in layers. After each layer is compacted, a urea-calcium acetate cementing solution is sprayed to cause calcium carbonate to precipitate evenly along its depth, forming a low-permeability solidified soil layer. Vegetation is then sown on the surface to form biological reinforcement. The abrupt change in permeability coefficient between the solidified soil layer and the drainage layer creates a capillary resistance effect. Combined with the reinforcement of vegetation roots and the buffering effect of raindrops from the above-ground parts, this achieves a synergistic enhancement of structural seepage prevention and ecological protection, effectively solving the problems of stability, erosion resistance, and long-term durability of steep slope cover layers.

Description

Technical Field

[0001] This application relates to the field of slope reinforcement technology in geotechnical engineering, and more specifically, to a slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy, and its construction method. Background Technology

[0002] In recent decades, climate change has exacerbated the global water cycle, leading to more frequent extreme rainfall events. Rainwater infiltration is a key cause of soil slope instability, reducing soil matrix suction and increasing water content, thereby weakening shear strength and lowering the slope's stability coefficient. To address this problem, current engineering projects commonly employ measures such as concrete retaining walls and shotcrete slope protection. However, while concrete can quickly impart high strength to the soil and reduce rainwater infiltration, its high alkalinity and hardening effect severely damage the soil's ecological environment. Furthermore, due to the significantly reduced porosity, it restricts the transport of water and air between the soil and vegetation, hindering normal vegetation growth. To mitigate the negative environmental effects, high molecular polymers such as polyacrylamide, lignin, and xanthan gum have also been developed and applied, but their readily biodegradable properties result in insufficient long-term durability, making it difficult to meet the long-term stability requirements of slope engineering.

[0003] For controlling rainwater infiltration, capillary-impeded soil cover technology offers an innovative approach based on the unsaturated properties of soil. This technology utilizes the abrupt change in permeability coefficient between coarse and fine soil layers to impede water infiltration, primarily applied in sanitary landfills for municipal solid waste. The cover layer consists of a fine-grained soil layer on top and a coarse-grained soil layer below, using the difference in permeability coefficient between the two layers to reduce water infiltration from the fine-grained soil downwards. However, directly applying this technology to steeper engineering slopes presents significant technical challenges. This is because the slope of landfill cover layers is typically less than 20 degrees, while the slope of engineering soil slopes can reach 45 degrees or even steeper, representing a difference of more than two times. The increased slope leads to a sharp increase in the sliding force of the cover layer's own weight along the slope surface. The weaker fine-grained soil layer in traditional cover layers may not be able to resist this sliding force, resulting in shallow sliding or localized spalling and collapse. Meanwhile, long-term rainfall erosion leads to the loss of fine-grained soil and vegetation degradation in the overlying layer, undermining its protective effect. This accelerates rainwater infiltration and gradually saturates the fine-grained soil, further reducing soil strength and slope stability. Furthermore, due to the cyclical changes in the natural environment, fine-grained soil undergoes repeated wet-dry cycles, resulting in soil structure deterioration, altered interlayer contact, and increased susceptibility to shrinkage cracks. These cracks become preferential channels for rapid rainwater infiltration on steep slopes, penetrating the capillary barrier layer, further reducing the overall soil integrity, and exacerbating the risk of mechanical instability.

[0004] In recent years, urease-induced calcium carbonate precipitation technology has attracted much attention due to its environmental friendliness and significant reinforcement effect. This technology utilizes urease to catalyze the hydrolysis of urea, generating carbonate ions that react with calcium ions to form calcium carbonate precipitate. The resulting calcium carbonate can cement soil particles, increasing soil strength and reducing the permeability coefficient. Addressing the challenges of applying fine-grained soil capillary cover layers to engineering slopes, this technology can cement loose soil particles into aggregates, increasing their strength and internal friction angle, thus fixing them more firmly to the slope. Through cementation and filling effects, it enhances the soil's resistance to rainfall erosion and wet-dry cycles. However, current enzyme-induced calcium carbonate precipitation technologies employ grouting and surface infiltration methods, leading to highly uneven distribution of the calcium carbonate precipitate within the soil, with concentrations in the shallow layer or near the grouting channels. This unevenness prevents the formation of a consistent depth and stable reinforcement layer within the capillary-impacted cover layer, thus failing to meet the requirements for erosion resistance and long-term stability.

[0005] Therefore, an optimized construction scheme for slope cover layer that integrates enzyme-induced calcium carbonate precipitation with vegetation is desired. Summary of the Invention

[0006] This application is made in order to solve the above-mentioned technical problems.

[0007] According to one aspect of this application, a method for constructing a slope cover layer that synergistically induces calcium carbonate precipitation and vegetation is provided, comprising: S1. The construction waste is crushed and screened to obtain recycled aggregate with a particle size of 10mm-50mm. The recycled aggregate is then laid and compacted in layers on the excavated and leveled slope surface to form a coarse particle guide layer. S2. Lay geotextile on the surface of the coarse particle drainage layer, with an overlap width of not less than 100mm between adjacent geotextiles and stitched together to form a reverse filter isolation layer; S3. The dried sword bean seeds are crushed and sieved to obtain dried sword bean powder. The dried sword bean powder and the sieved slag are dry-mixed in a mixing equipment to obtain mixed soil. At the same time, urea and calcium acetate are dissolved in water at a molar ratio of urea to calcium ions of 1:1 and then mixed to prepare a cementing solution. S4. The mixed soil is laid and compacted in layers on the filter isolation layer. After each layer is compacted, the cementing liquid is evenly sprayed onto the surface of the compacted soil using a pressure spraying device. The cementing liquid penetrates into the soil and undergoes urea hydrolysis and calcium carbonate precipitation under the catalysis of urease provided by the dried sword bean powder. The layer laying, compaction and spraying process is repeated until the design thickness is reached to form a solidified soil layer. S5. Before the final compaction of the solidified soil layer, herbaceous plant seeds and woody plant seeds are sown at a set sowing density at a depth of 10mm below the surface of the uncompacted soil. After the seeds are buried and fixed as the layer is compacted, a breathable and water-retaining green net is covered on the surface of the solidified soil layer and sprayed for maintenance to form a vegetation layer.

[0008] According to another aspect of this application, an enzyme-induced calcium carbonate precipitation and vegetation synergistic slope cover layer is provided, which is constructed using the above-described construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergistic slope cover layer.

[0009] Compared with existing technologies, this application provides an enzyme-induced calcium carbonate precipitation and vegetation-synergistic slope cover layer and its construction method. First, a coarse-particle drainage layer composed of recycled construction waste aggregate is constructed on the excavated and leveled slope surface, and geotextile is laid on its surface as a filter layer. Then, a mixing-type enzyme-induced calcium carbonate precipitation process is used, where dried sword bean powder is used as a urease source and pre-mixed evenly with the slag soil. This mixture is then layered, compacted, and sprayed with urea-calcium acetate cementitious liquid, causing calcium carbonate to precipitate evenly along the soil depth, forming a high-strength, low-permeability solidified soil layer. This fundamentally solves the problems of traditional injection methods. The uneven distribution of calcium carbonate caused by the grouting method significantly improves the mechanical strength and resistance to degradation of the fine-grained soil layer. Finally, herbaceous and woody plant seeds are sown on the surface of the solidified soil layer and covered to form a vegetation layer. Through the biological reinforcement effect of the vegetation roots and the raindrop buffering effect of the above-ground parts, a structural seepage prevention-ecological protection composite system is constructed in synergy with the solidified soil layer. A significant change in permeability coefficient is formed between this low-permeability solidified layer and the underlying high-permeability drainage layer, creating a highly efficient capillary resistance effect. The synergistic effect of the three effectively solves the problems of stability, durability and seepage prevention of the cover layer in steep slope environments. Attached Figure Description

[0010] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0011] Figure 1 This is a flowchart of a construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application.

[0012] Figure 2 This is a flowchart of step S3 of the construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application.

[0013] Figure 3 This is a flowchart of step S4 of the construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application.

[0014] Figure 4 This is a flowchart of step S5 of the construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application.

[0015] Figure 5 This is a schematic diagram of the structure of a slope cover layer that combines enzyme-induced calcium carbonate precipitation with vegetation. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Traditional capillary retaining capillary layers face key technical challenges in engineering slope applications, including insufficient strength of fine-grained soil layers leading to steep slope landslides, soil loss due to rainfall erosion, and crack development caused by wet-dry cycles. Existing enzyme-induced calcium carbonate precipitation technologies, such as grouting and surface infiltration, suffer from uneven calcium carbonate distribution and insufficient deep reinforcement. To address these issues, this invention proposes a systematic construction method: First, construction waste is crushed and screened to obtain recycled aggregate with a particle size of 10mm to 50mm. This aggregate is then layered and compacted on the excavated and leveled slope surface to form a highly permeable coarse-grained drainage layer. A geotextile is then laid on its surface to construct a filter layer. Next, dried sword bean seeds are crushed and sieved to obtain urease-rich dried sword bean powder. This powder is then thoroughly dry-mixed with sieved slag in a mixing device to ensure uniform dispersion of the urease source in the soil. Finally, this mixed soil is layered and compacted on the filter layer. Immediately after each layer is compacted, a pressure sprayer is used to evenly spray a urea-calcium acetate binder solution prepared at a 1:1 molar ratio of urea to calcium ions onto the surface of the compacted soil. This allows the binder solution to penetrate the soil pores and contact with pre-mixed urease. Under the catalysis of urease, urea undergoes a hydrolysis reaction to generate carbonate ions. These carbonate ions react with calcium ions at the contact points of soil particles to precipitate calcium carbonate, forming cement bridges. This process of layering, compaction, and spraying is repeated until the designed thickness is achieved, resulting in a compaction degree of not less than 90% and a saturated permeability coefficient of less than 1×10⁻⁶. -6A solidified soil layer with a density of cm / s is formed. Before the final compaction of the solidified soil layer, herbaceous and woody plant seeds are sown at a set density 10mm below the surface of the uncompacted soil. As this layer is compacted, the seeds are buried and fixed. A breathable and water-retaining green net is then covered on the surface of the solidified soil layer and sprayed with water to form a vegetation layer. This mixed-enzyme-induced calcium carbonate precipitation process achieves uniform and stable precipitation of calcium carbonate along the soil depth, fundamentally improving the mechanical strength, internal friction angle, and erosion resistance of the fine-grained soil layer, enabling it to stably adhere to steep slopes. A significant abrupt change in permeability coefficient is formed between this low-permeability solidified layer and the underlying high-permeability drainage layer, creating a highly efficient capillary barrier effect that greatly hinders rainwater infiltration. Simultaneously, the root system of the surface vegetation provides biological reinforcement, while the above-ground parts reduce raindrop kinetic energy and slow runoff. The synergistic effect of these three factors effectively solves the problems of stability, durability, and impermeability of the cover layer in steep slope environments, significantly improving the long-term stability and erosion resistance of the slope.

[0018] The technical solution of this application proposes a construction method for a slope cover layer that combines enzyme-induced calcium carbonate precipitation with vegetation synergy. Figure 1 This is a flowchart illustrating a construction method for an enzyme-induced calcium carbonate precipitation and vegetation-synergistic slope cover layer according to an embodiment of this application. Figure 1 As shown, the construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to the embodiment of this application includes the following steps: Step S1, crushing and screening construction waste to obtain recycled aggregate with a particle size of 10mm-50mm, and laying and compacting the recycled aggregate in layers on the excavated and leveled slope surface to form a coarse particle guide layer; Step S2, laying geotextile on the surface of the coarse particle guide layer, with the overlap width of adjacent geotextiles not less than 100mm and stitched together to form a filter isolation layer; Step S3, crushing and screening dried sword bean seeds to obtain dried sword bean powder, and dry mixing the dried sword bean powder with the screened slag in a mixing equipment to obtain mixed soil, while urea and calcium acetate are mixed according to the urea to calcium ion molar ratio. The soil is dissolved in water at a 1:1 ratio and then mixed to prepare a cementing solution. In step S4, the mixed soil is laid and compacted in layers on the filter isolation layer. After each layer is compacted, the cementing solution is evenly sprayed onto the surface of the compacted soil using a pressure spraying device. This allows the cementing solution to penetrate the soil and undergo urea hydrolysis and calcium carbonate precipitation under the catalysis of urease provided by the dried sword bean powder. The layering, compaction, and spraying process is repeated until the designed thickness is reached to form a solidified soil layer. In step S5, before the final layer of the solidified soil layer is compacted, herbaceous plant seeds and woody plant seeds are sown at a set sowing density 10 mm below the surface of the uncompacted soil. After the seeds are buried and fixed as the layer is compacted, the surface of the solidified soil layer is covered with a breathable and water-retaining green net and sprayed for maintenance to form a vegetation layer.

[0019] Specifically, in step S1, construction waste is crushed and screened to obtain recycled aggregate with a particle size of 10mm-50mm. The recycled aggregate is then layered and compacted on the excavated and leveled slope surface to form a coarse-particle drainage layer. It is understandable that traditional capillary-retaining capillary layers face technical challenges in steep slope environments, such as insufficient strength of fine-particle soil layers leading to landslides, soil loss due to rainfall erosion, and crack development caused by wet-dry cycles. While solidified soil layers can improve the strength and impermeability of fine-particle soil through enzyme-induced calcium carbonate precipitation technology, prolonged rainfall can still cause rainwater to gradually accumulate in the solidified soil layer. Without effective drainage channels, the accumulated rainwater will gradually saturate the solidified soil layer and continuously seep downwards into the slope, causing an increase in pore water pressure and a decrease in effective stress, ultimately leading to slope instability. Therefore, in the technical solution of this application, construction waste is crushed and screened to obtain recycled aggregate with a particle size of 10mm to 50mm. The recycled aggregate is then layered and compacted on the excavated and leveled slope surface to form a coarse-particle drainage layer. This creates a highly permeable drainage channel beneath the solidified soil layer. The abrupt change in permeability between the coarse-particle drainage layer and the solidified soil layer creates a capillary repression effect, causing rainwater to be trapped in the solidified soil layer and rapidly discharged along the coarse-particle drainage layer via lateral drainage, preventing rainwater from continuously infiltrating into the slope body. In this way, while ensuring the low permeability and water-blocking function of the solidified soil layer, the threat of rainwater accumulation in the solidified soil layer to the slope stability is effectively eliminated, significantly improving the long-term seepage prevention performance and overall stability of the slope.

[0020] More specifically, in the embodiments of this application, step S1 includes: S1.1. Mechanically excavating the soil slope according to the designed slope ratio, removing boulders and debris with a diameter greater than 100mm from the slope surface, leveling and compacting the excavated slope surface to control the slope height difference within 20mm, so as to obtain a qualified leveled slope surface; S1.2. Feeding construction waste into a crusher for crushing, and then screening it through a multi-stage vibrating screen to cut particles with a particle size of 10mm-50mm to obtain recycled aggregate, wherein the non-uniformity coefficient of the recycled aggregate is greater than 15 and the curvature coefficient is 1-3; S1.3. Laying the recycled aggregate in layers on the qualified leveled slope surface, with each layer having a loose thickness of 110mm, and using a plate vibrator to vibrate and compact each layer to a thickness of 100mm, repeating the laying and compaction until the designed total thickness is reached, forming a compaction degree of not less than 90% and a saturated permeability coefficient of 1×10. -2 -1×10 -1 A coarse-particle guide layer with a compaction rate of cm / s. It is worth mentioning that the compaction degree of the coarse-particle guide layer is not less than 90% and the thickness is 100mm-200mm.

[0021] Specifically, in one particular example of this application, the soil slope is mechanically excavated according to the design slope ratio. Excavators or bulldozers are used to excavate section by section from top to bottom along the design slope line, shaping the irregular surface of the soil slope into a regular slope that meets the design slope ratio requirements. During the excavation process, boulders and debris with a diameter greater than 100mm are removed from the slope surface. Manual labor combined with machinery is used to remove the boulders and debris from the slope surface and transport them away from the construction area. After excavation, the excavated slope surface is leveled and compacted. A grader or manual scraper is used to finely level the slope surface, eliminating local protrusions and depressions. Subsequently, a vibratory tamper or impact tamper is used to compact the leveled slope surface, improving its density and bearing capacity. During the leveling and compaction process, a level or laser rangefinder is used to monitor the slope elevation difference in real time, ensuring that the elevation difference is controlled within 20mm to obtain a qualified leveled slope surface. Then, construction waste such as concrete blocks, waste bricks, and waste mortar blocks are fed into a crusher for crushing, followed by screening using a multi-stage vibrating screen to obtain particles with a diameter of 10mm to 50mm, thus obtaining recycled aggregate. It is worth noting that the uniformity coefficient of the recycled aggregate is greater than 15, and the curvature coefficient is 1-3. The recycled aggregate is then laid in layers on a leveled slope. A loader or manual labor is used to transport the recycled aggregate to the leveled slope, laying it layer by layer from bottom to top along the slope direction. Each layer has a loose thickness of 110mm. A scraper or rake is used to level the loosely laid recycled aggregate, ensuring a smooth surface and uniform thickness. After each loosely laid layer is completed, a plate vibrator is used to compact it along the slope direction until a thickness of 100mm is achieved. After compaction, the dry density of the compacted layer is tested using the sand cone method or ring cutter method, and the degree of compaction is calculated to ensure that the degree of compaction is not less than 90%. Repeat the paving and compaction process, layer by layer, until the designed total thickness of 100mm to 200mm is reached, resulting in a compaction degree of not less than 90% and a saturated permeability coefficient of 1×10⁻⁶. -2 Up to 1×10 -1 A coarse-particle packing layer with a speed of cm / s.

[0022] Specifically, in step S2, geotextile is laid on the surface of the coarse-particle drainage layer, with an overlap width of not less than 100mm between adjacent geotextiles, and they are sewn together to form a filter isolation layer. It should be understood that, since the coarse-particle drainage layer is composed of recycled aggregate with a particle size of 10mm to 50mm, its pore size is relatively large and its saturated permeability coefficient is 1×10⁻⁶. -2 Up to 1×10 -1The subsequent solidified soil layer is formed by mixing slag that has passed through a 5mm sieve with dried broad bean powder. The fine soil particles are much smaller than the pore size of the coarse-grained drainage layer. During the layering and compaction of the solidified soil layer, and during the subsequent spraying of the cementing liquid, the fine soil particles migrate downwards under the influence of gravity and liquid, entering the pores of the coarse-grained drainage layer. This causes the pores of the coarse-grained drainage layer to be filled and blocked by fine particles, ultimately leading to the failure of the capillary resistance effect. Therefore, in the technical solution of this application, geotextile is further laid on the surface of the coarse-grained drainage layer. The overlap width of adjacent geotextiles is not less than 100mm and they are sewn together to form a filter isolation layer. This creates a filter barrier between the coarse-grained drainage layer and the solidified soil layer, allowing water to pass freely while preventing the fine soil particles from migrating downwards, ensuring that the pore structure of the coarse-grained drainage layer is not filled and blocked by fine particles.

[0023] More specifically, in the embodiments of this application, step S2 includes: S2.1. Inspecting and tidying the surface of the coarse particle guide layer to eliminate sharp and protruding aggregate particles, thereby obtaining a pretreated base surface; S2.2. Laying short-fiber needle-punched geotextile with a specification of 300g / m² along the slope direction on the pretreated base surface, so that the geotextile is flat and tightly attached to the surface without wrinkles or gaps, and the overlap width of adjacent geotextiles is not less than 100mm; S2.3. Fixing the overlap of adjacent geotextiles by sewing to form a reverse filter isolation layer.

[0024] Specifically, in one particular example of this application, the surface of the coarse-particle guide layer is inspected and prepared. A manual inspection is conducted section by section along the slope direction to identify protruding aggregate particles larger than 50mm or with sharp edges. These sharp, protruding aggregate particles are removed using a localized particle replacement method and replaced with aggregate particles of appropriate size, thus eliminating the sharp, protruding aggregate particles and obtaining the pretreated base surface. Then, a 300g / m² short-fiber needle-punched geotextile is laid along the slope direction on the pretreated base surface. The geotextile rolls are unfolded piece by piece from the top of the slope to the bottom using a combination of manual labor and machinery. During the laying process, a hand-held scraper or soft broom is used to smooth the geotextile surface, eliminating wrinkles and gaps, ensuring the geotextile is flat and tightly adhered to the pretreated base surface without wrinkles or gaps. The overlap width between adjacent geotextile strips should be no less than 100mm. When laying the second and subsequent geotextile strips, the edge of the newly laid geotextile should overlap the edge of the already laid geotextile. The overlap width should be measured with a tape measure to ensure that it is no less than 100mm. Finally, the overlap of adjacent geotextile strips should be fixed by sewing. A portable sewing machine should be used to continuously sew along the overlap, using a double-lock stitch technique with a stitch length controlled between 6mm and 10mm. High-strength polyester thread with a tensile strength of no less than 300N should be used for sewing. After sewing, a tensile test should be performed on the sewn area to ensure that the tensile strength of the seam is no less than 60% of the tensile strength of the geotextile itself, thus forming a reverse filter isolation layer.

[0025] Specifically, in step S3, dried sword bean seeds are crushed and sieved to obtain dried sword bean powder. The dried sword bean powder is then dry-mixed with sieved slag in a mixing device to obtain a mixed soil. Simultaneously, urea and calcium acetate are dissolved in water at a urea to calcium ion molar ratio of 1:1 and mixed to prepare a cementing solution. It should be understood that because traditional enzyme-induced calcium carbonate precipitation technology uses grouting and surface infiltration methods, when the cementing solution permeates from the soil surface or grouting holes into the interior, the contact between the urease source and the reaction substrate only occurs in the area reached by the liquid front. This results in calcium carbonate precipitation mainly accumulating in the shallow layer or near the grouting channel, while the deeper areas suffer from insufficient reinforcement due to obstructed cementing solution permeation or insufficient urease concentration. This leads to significant uneven distribution of calcium carbonate, making it impossible to form a uniformly deep, stable, low-permeability water-blocking layer in the capillary barrier capillary layer, which is insufficient to meet the requirements of slope engineering for erosion resistance and long-term stability. Therefore, in the technical solution of this application, the dried sword bean seeds are further crushed and sieved to obtain dried sword bean powder. The dried sword bean powder and the sieved slag are dry-mixed in a mixing equipment to obtain mixed soil. At the same time, urea and calcium acetate are dissolved in water at a molar ratio of urea to calcium ions of 1:1 and mixed to prepare a cementing solution. In this way, the urease source is uniformly dispersed in the form of solid powder between the slag particles before the soil is laid. This changes the spatial distribution of urease in the soil from the liquid phase permeation gradient distribution of the traditional method to a uniform distribution of solid premixing. When the cementing solution is sprayed subsequently, the urea and calcium ions in the cementing solution can fully contact and react with the premixed urease source at any depth in the soil, so as to achieve uniform precipitation of calcium carbonate along the depth of the soil layer. This approach overcomes the shortcomings of traditional grouting or surface infiltration methods, which result in calcium carbonate enrichment in shallow layers and insufficient reinforcement in deep layers. It significantly improves the overall strength, internal friction angle, and erosion resistance of the solidified soil layer, ensuring the functional integrity and long-term reliability of the solidified soil layer as the core low-permeability barrier of the capillary barrier system.

[0026] Figure 2 This is a flowchart of step S3 of the construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application. Figure 2As shown, step S3 includes: S3.1. Feeding dried sword bean seeds into a pulverizer for pulverization, passing the pulverized product through a 1000-mesh sieve, collecting the sieve-underfill material to obtain dried sword bean powder; S3.2. Adding the slag soil after passing through a 5mm sieve and the dried sword bean powder to a mixing device at a mass ratio of 85000:480 for thorough dry mixing, so that the dried sword bean powder is evenly dispersed in the slag soil to obtain a mixed soil body; S3.3. Dissolving urea with a purity greater than 95% and calcium acetate with a purity greater than 95% in water and stirring until completely dissolved, then mixing them, wherein the molar ratio of urea to calcium ions is 1:1, and the mass ratio of slag soil, dried sword bean powder, urea, calcium acetate and water is 85000:480:(90-720):(237-1896):24000, to prepare a cementing solution.

[0027] More specifically, in one particular example of this application, dried sword bean seeds are fed into a pulverizer for crushing. A high-speed pulverizer or ball mill is used to mechanically crush the dried sword bean seeds. The pulverizer speed is set to 8000 rpm to 12000 rpm, and the crushing time is set to 5 to 10 minutes, crushing the dried sword bean seeds into powder with a particle size of less than 100 μm. The pulverized product is then sieved through a 1000-mesh sieve. A 1000-mesh standard sieve with a pore size of 13 μm is used to sieve the product. The sieve is fixed on a vibrating screen, and the vibrating screen is started to vibrate the sieve at a frequency of 30 Hz to 50 Hz. The pulverized product passes through the sieve pores under vibration, and particles with a particle size of less than 13 μm are collected. The undersize material is collected to obtain dried sword bean powder, which is rich in urease with an activity of 15 U / g to 25 U / g. Next, the slag soil that has passed through a 5mm sieve and the dried sword bean powder are added to a mixing equipment at a mass ratio of 85000:480 for thorough dry mixing. A forced mixer is used as the mixing equipment. 17000 kg of slag soil that has passed through a 5mm sieve and 96 kg of dried sword bean powder are added to the mixing drum of the forced mixer in batches. The mixer is started and the mixing blades rotate at a speed of 30 to 50 rpm. The mixing time is set to 8 to 12 minutes to ensure that the dried sword bean powder is evenly dispersed among the slag particles under mechanical mixing, resulting in a mixed soil. After mixing, 5 to 8 samples are taken from different locations in the mixed soil using a random sampling method. The mass percentage of dried sword bean powder in each sample is determined, and the ratio of the sample standard deviation to the mean is calculated to ensure that the coefficient of variation of the mixing uniformity is less than 5%. Then, urea with a purity greater than 95% and calcium acetate with a purity greater than 95% are dissolved separately in water and stirred until completely dissolved before being mixed. According to the required mass ratio of slag, dried sword bean powder, urea, calcium acetate and water of 85000:480:90 to 720:237 to 1896:24000, 18 kg of urea with a purity greater than 95% and 47.4 kg of anhydrous calcium acetate with a purity greater than 95% are weighed. The urea is added to the first dissolving container and 1200 L of water is added. The mixture is stirred with a mechanical stirrer at 200 rpm to 300 rpm for 15 to 20 minutes until the urea is completely dissolved to form a urea solution. The anhydrous calcium acetate is added to the second dissolving container and 1200 L of water is added. The mixture is stirred with a mechanical stirrer at 200 rpm to 300 rpm for 20 to 30 minutes until the calcium acetate is completely dissolved to form a calcium acetate solution. The urea solution and calcium acetate solution were poured into a mixing container and mixed. The mixture was stirred with a mechanical stirrer at 150 to 250 rpm for 10 to 15 minutes to ensure that the two solutions were fully mixed and homogeneous. A cementing solution with a total volume of 4800 L was prepared, in which the molar ratio of urea to calcium ions was 1:1.

[0028] Specifically, in step S4, the mixed soil is laid and compacted in layers on the filter isolation layer. After each layer is compacted, a pressure spraying device is used to evenly spray the cementing liquid onto the surface of the compacted soil, so that the cementing liquid penetrates into the soil and undergoes urea hydrolysis and calcium carbonate precipitation under the catalysis of urease provided by the dried sword bean powder. The layer laying, compaction and spraying process is repeated until the designed thickness is reached to form a solidified soil layer. It is understandable that, since the dried sword bean powder in the mixed soil is evenly dispersed among the slag particles, the urease in the dried sword bean powder is a solid protein molecule, and its catalytic activity can only be fully exerted in an aqueous environment. However, the mixed soil has a low moisture content in the dry mixing state, so the urease cannot effectively contact and catalyze the reaction with the urea substrate. At the same time, although the urea and calcium acetate in the cementing solution have dissolved in the water to form reaction substrates, if the cementing solution is directly sprayed onto the surface of the loose mixed soil, the liquid will quickly seep downwards under the action of gravity and run off along the slope, resulting in a very uneven distribution of the cementing solution in the soil and insufficient effective retention time, which cannot ensure the full and uniform distribution of the calcium carbonate precipitation reaction. Therefore, in the technical solution of this application, the mixed soil is further laid and compacted in layers on the filter isolation layer. After each layer is compacted, a pressure spraying device is used to evenly spray the cementing liquid onto the surface of the compacted soil, so that the cementing liquid penetrates into the soil and undergoes urea hydrolysis and calcium carbonate precipitation under the catalysis of urease provided by the dried sword bean powder. The layer laying, compaction and spraying process is repeated until the designed thickness is reached to form a solidified soil layer. In this way, the porosity of the mixed soil is reduced to a reasonable range and the soil density is increased through the compaction operation, so that the cementing liquid sprayed later can evenly penetrate into the pores of the compacted soil under the combined drive of capillary action and gravity, ensuring that the cementing liquid and the premixed urease source are in full contact in the soil depth direction. At the same time, the compacted soil structure can effectively retain the cementing liquid and provide a stable aqueous environment for the enzyme catalytic reaction, so that urea undergoes hydrolysis under the catalysis of urease to generate carbonate ions. The carbonate ions and calcium ions undergo calcium carbonate precipitation at the contact point of soil particles to form cement bridges. This allows for the uniform and stable precipitation of calcium carbonate along the soil depth. Through the cementing and filling effects of calcium carbonate, the overall strength and impermeability of the solidified soil layer are significantly improved, resulting in a compaction degree of not less than 90% and a saturated permeability coefficient of less than 1×10⁻⁶. -6 A low-permeability solidified soil layer with a flow rate of cm / s and a total thickness of 200mm-600mm ensures the reliability of the capillary resistance effect and the long-term stability of the slope.

[0029] Figure 3 This is a flowchart of step S4 of the construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application. Figure 3As shown, step S4 includes: S4.1. Dividing the mixed soil and cementitious liquid into equal portions according to the number of construction layers, taking one portion of the mixed soil and evenly laying it on the filter isolation layer and leveling it, then compacting it with compaction machinery until the single layer thickness is 100mm and the compaction degree is not less than 90%, thus obtaining a physically compacted single layer; S4.2. Using a pressure spraying device, evenly spraying one portion of cementitious liquid onto the surface of the physically compacted single layer, allowing the cementitious liquid to penetrate into the pores of the physically compacted single layer and contact with the urease released by the dried sword bean powder. Under the catalysis of urease, urea undergoes a hydrolysis reaction to generate carbonate ions. The carbonate ions and calcium ions undergo a calcium carbonate precipitation reaction at the contact points of soil particles to form cement bridges, thus obtaining a mineralized single layer; S4.3. Using the mineralized single layer as the base surface, repeating the laying, compaction, and spraying processes of steps S4.1 and S4.2, layer by layer upwards, until the total thickness reaches 200mm-600mm, and the saturated permeability coefficient is tested to be less than 1×10. -6 After reaching a speed of cm / s, a solidified soil layer is formed.

[0030] Accordingly, in step S4.1, the mixed soil and cementitious liquid are divided equally according to the number of construction layers. One portion of the mixed soil is evenly laid on the filter isolation layer and leveled. It is then compacted using compaction machinery until the single layer thickness is 100mm and the compaction degree is not less than 90%, thus obtaining a physically compacted single layer. It is understandable that because the solidified soil layer needs to be constructed layer by layer through a cycle of paving, compaction, and spraying of binder, and the total amount of mixed soil and binder is a fixed value pre-mixed based on the designed total thickness of the solidified soil layer of 200mm to 600mm, if the mixed soil and binder are not properly distributed, it may result in some layers having too much mixed soil and too little binder, or some layers having too much binder and too little mixed soil. This will cause significant differences in the amount of calcium carbonate precipitation between layers, resulting in an uneven distribution of strength and permeability coefficient in the depth direction of the solidified soil layer. This will fail to meet the requirements of capillary-impeded capillary cover for uniform low permeability performance. At the same time, the mixed soil has high porosity and loose structure in the uncompacted state. If binder is sprayed directly, the liquid will quickly seep downwards under gravity and run off along the slope, resulting in the binder not being evenly distributed in the soil and insufficient effective retention time. The urease catalytic reaction cannot proceed fully, and the amount of calcium carbonate precipitation is far lower than the design target value. Therefore, in the technical solution of this application, the mixed soil and cementitious liquid are further divided equally according to the number of construction layers. One portion of the mixed soil is evenly laid on the filter isolation layer and leveled. It is then compacted using compaction machinery until the single layer thickness is 100mm and the compaction degree is not less than 90%, thus obtaining a physically compacted single layer. This ensures that the ratio of mixed soil to cementitious liquid in each layer strictly follows the design formula where the mass ratio of slag, dried sword bean powder, urea, calcium acetate, and water is 85000:480:90 to 720. The requirements of :237 to 1896:24000 ensure consistent calcium carbonate precipitation across all layers. Simultaneously, compaction reduces the porosity of the mixed soil from the initial 40%-50% to 25%-35%, increasing soil density and forming a stable pore structure. This allows subsequent sprayed cementitious liquid to uniformly infiltrate the compacted soil pores under the combined effects of capillary action and gravity, preventing rapid loss and providing sufficient reaction time and a stable aqueous environment for the urease catalytic reaction. This ensures uniform calcium carbonate precipitation across all layers in the solidified soil layer, forming a stable, low-permeability, water-resistant layer. Furthermore, the compacted soil structure effectively retains the cementitious liquid and ensures the full catalytic reaction of the enzyme, significantly improving the overall strength and impermeability of the solidified soil layer, meeting the requirements of a capillary-resistant capillary layer for uniform low permeability and long-term stability.

[0031] More specifically, in a specific example of this application, the mixed soil and cementitious liquid are divided equally according to the number of construction layers. Based on the design total thickness of the solidified soil layer being 200mm and the single-layer compaction thickness being 100mm, the number of construction layers is determined to be 2. The 17,000kg of mixed soil is divided equally into 2 construction layers, resulting in a required mass of 8,500kg of mixed soil per layer. The 4,800L of cementitious liquid is also divided equally into 2 construction layers, resulting in a required volume of 2,400L of cementitious liquid per layer. A portion of the mixed soil is evenly spread on the filter isolation layer and leveled. A loader is used to transport 8,500kg of mixed soil to the surface of the filter isolation layer and spread it from bottom to top along the slope. During the spreading process, a scraper is used to scrape and level the mixed soil back and forth along the slope to spread it into a uniform thickness layer. The loose layer thickness is controlled between 110mm and 120mm to ensure that the surface of the layer is flat and without significant height differences. The compaction is carried out using compaction machinery to achieve a single layer thickness of 100mm and a compaction degree of not less than 90%. A vibratory roller is used to compact the paving layer, with the vibration frequency set to 50Hz and the amplitude set to 0.5mm. The roller is rolled at a uniform speed from bottom to top along the slope, with the rolling speed controlled between 1.5m / min and 2.5m / min. The first pass of rolling uses static compaction mode to initially compact the mixed soil. The second to fourth passes of rolling use vibratory compaction mode to interlock the mixed soil particles under vibration and expel air from the pores. The fifth and sixth passes of rolling use static compaction mode to finish the surface of the compacted layer, compacting it to a single layer thickness of 100mm. After compaction, the dry density of the compacted layer is tested using the sand cone method. Three to five representative locations are selected on the surface of the compacted layer. A cylindrical test pit with a diameter of 150 mm and a depth of 100 mm is dug at each location. The mass of the excavated mixed soil is weighed and its moisture content is determined. The dry density is calculated. The measured dry density is compared with the maximum dry density measured by the indoor standard compaction test to calculate the degree of compaction. The degree of compaction is ensured to be not less than 90%, thus obtaining a physically compacted single layer.

[0032] Accordingly, in step S4.2, a portion of cementing solution is uniformly sprayed onto the surface of the physically compacted monolayer using a pressure spraying device. This allows the cementing solution to penetrate the pores of the physically compacted monolayer and come into contact with urease released from the dried sword bean powder within it. Under the catalysis of urease, urea undergoes a hydrolysis reaction to generate carbonate ions. These carbonate ions react with calcium ions at the contact points of soil particles to form calcium carbonate precipitation, creating cement bridges and resulting in a mineralized monolayer. It should be understood that the enzyme-induced calcium carbonate precipitation reaction requires the cementing solution to penetrate into the pores of the compacted soil and fully contact the premixed urease source. The spray volume of the cementing solution directly determines the amount of reaction substrate input and the final amount of calcium carbonate precipitation. If the spray volume is insufficient, some urease will fail to catalyze the reaction due to a lack of reaction substrate, resulting in a calcium carbonate precipitation amount lower than the design target value, and insufficient strength and impermeability of the solidified soil layer. If the spray volume is excessive, the excess cementing solution cannot be contained by the soil pores and will be lost along the slope, causing material waste and potentially environmental pollution. Therefore, in the technical solution of this application, a pressure spraying device is further used to uniformly spray a cementing liquid onto the surface of the physically compacted monolayer. This allows the cementing liquid to penetrate into the pores of the physically compacted monolayer and come into contact with urease released from the dried sword bean powder. Under the catalysis of urease, urea undergoes a hydrolysis reaction to generate carbonate ions. The carbonate ions react with calcium ions at the contact points of soil particles to form calcium carbonate precipitation, creating cement bridges and resulting in a mineralized monolayer. This uniform spraying and penetration of the cementing liquid provides sufficient reaction substrate and a stable aqueous environment for the urease-catalyzed reaction, ensuring that the urea hydrolysis reaction and calcium carbonate precipitation reaction proceed fully in the soil depth direction, allowing calcium carbonate to precipitate uniformly at the contact points of soil particles and form cement bridges. In this way, the cementing effect of calcium carbonate firmly connects adjacent soil particles, significantly improving the overall strength and internal friction angle of the solidified soil layer. Simultaneously, the calcium carbonate crystals fill the soil pores, increasing the saturated permeability coefficient from 1×10⁻⁶ before compaction. -4 cm / s decreased to 1×10 -6 When the flow rate is below cm / s, a low-permeability water-blocking layer is formed, ensuring the reliability of the capillary blocking effect and the long-term stability of the slope.

[0033] More specifically, in a specific example of this application, a pressure spraying device is used to uniformly spray a binder onto the surface of a physically compacted monolayer. The operator, carrying the spraying device, moves at a constant speed from bottom to top along the slope, maintaining a constant distance between the nozzle and the surface of the physically compacted monolayer during spraying to ensure sufficient and uniform atomization of the binder. The spray volume of the binder is calculated based on the porosity and thickness of the physically compacted monolayer, combined with a set liquid saturation. The construction area A of the physically compacted monolayer is 50 m², the compaction thickness H is 0.1 m, the porosity n of the compacted soil is 0.30, and the designed liquid saturation Sr is 0.70. The spray volume V of the binder is calculated based on a geometric pore-filling model. The calculation formula is: Substituting the values ​​into the formula, we get V = 50m² multiplied by 0.1m multiplied by 0.30 multiplied by 0.70, which gives V = 1.05m³, or 1050L. Specifically, the first term on the right-hand side of this formula... This represents the total volume of a physically compacted single layer, which includes both the volume of the soil particle skeleton and the pore volume, multiplied by the porosity. This represents the volume fraction of pores extracted from the total volume, yielding the total pore volume in a physically compacted monolayer, which is then multiplied by the design liquid saturation. This represents the proportion of the pore volume that needs to be filled with cementing fluid to the total pore volume, thus yielding the spray volume of the cementing fluid. This calculation method is based on the principle of pure geometric volume matching, ensuring that the volume of the sprayed binder matches the pore volume of the soil. This avoids insufficient spray volume leading to a lack of reactant substrate or excessive spray volume leading to liquid loss. Based on the calculated spray volume of 1050L, 2400L of binder is sprayed in batches onto the surface of the physically compacted monolayer. Each batch consists of 200L to 300L, with an interval of 10 to 15 minutes between batches. This allows sufficient time for the binder from the previous batch to penetrate into the soil pores before the next batch is sprayed, preventing surface liquid accumulation. After spraying, the binder penetrates into the pores of the physically compacted monolayer under the combined effects of capillary action and gravity. The penetration depth gradually expands from the surface to the lower layers. The penetration rate is affected by the soil porosity and the viscosity of the binder, with a penetration time of 30 to 60 minutes. After the cementing solution penetrates the pores, it comes into contact with the premixed dried sword bean powder within the pores. The dried sword bean powder absorbs water and swells in the aqueous environment, releasing urease. Urease, a protein catalyst, binds to urea molecules at its active sites to form an enzyme-substrate complex, catalyzing the hydrolysis of urea. The reaction equation is as follows: The reaction produces carbonate and ammonium ions. The reaction rate is affected by temperature and pH, with the fastest rate occurring at temperatures between 25°C and 37°C and pH values ​​between 7 and 9. Carbonate ions react with calcium ions in the cementitious solution at the contact points between soil particles to precipitate calcium carbonate. The reaction equation is as follows: The precipitation of calcium carbonate crystals occurs, preferentially nucleating and growing at rough areas of soil particle surfaces and particle contact points. The crystal morphology is calcite or aragonite, with a size ranging from 1 μm to 10 μm. Calcium carbonate crystals deposit at soil particle contact points, forming cemented bridges that firmly connect adjacent soil particles. These cemented bridges have a tensile strength of 5 MPa to 15 MPa, significantly improving the overall strength and internal friction angle of the soil. Simultaneously, the calcium carbonate crystals fill soil pores, reducing porosity from 0.30 to 0.20 to 0.25, and the saturated permeability coefficient from 1 × 10⁻⁶. -4 cm / s decreased to 1×10 -6 When the speed is below cm / s, a mineralized monolayer is obtained.

[0034] Specifically, in the in-situ infiltration and enzyme-induced mineralization reaction of the first embodiment described above, the spray volume of the cementing solution... Model filled by pure geometric pores It is confirmed that the calculation logic of this formula is entirely based on volume matching in physical space, that is, calculating the volume of cementing fluid to be injected based on the total pore volume of the compacted soil and the set liquid saturation. This calculation paradigm implicitly assumes a key idealization: once the cementing fluid enters the pores and comes into contact with the premixed urease source (dried sword bean powder), the urea hydrolysis reaction is completed with a complete and constant efficiency, and all reactants are quantitatively converted into calcium carbonate precipitate. However, this assumption is fundamentally contradictory to the actual physicochemical conditions of applying enzyme-induced calcium carbonate precipitation technology to the specific engineering scenario of slope construction, specifically in the following three dimensions.

[0035] The first drawback lies in the complete neglect of the nonlinear dependence of urease catalytic efficiency on ambient temperature. Urease is essentially a protein biocatalyst, and its three-dimensional conformation—that is, the spatial structure of the active site that determines its catalytic activity—is extremely sensitive to temperature. At the enzymatic level, the maximum reaction rate of urease... and Mi constant Both are nonlinear functions of temperature, and the catalytic activity changes with temperature in a typical bell-shaped curve: in the low-temperature region ( The thermal energy of enzyme molecules is insufficient to efficiently drive the formation of substrate-enzyme complexes, resulting in low catalytic activity. Activity gradually increases with increasing temperature and reaches an optimum temperature. Urease typically peaks at around 37°C; however, once it exceeds this temperature... The protein undergoes irreversible thermal denaturation, and the unfolding of the peptide chain leads to the permanent destruction of the active site, resulting in a sharp loss of catalytic ability.

[0036] In the specific engineering scenario of slope construction, the construction work spans different seasons and day-night cycles. The actual temperature of the slope surface can fluctuate drastically between 5°C and 55°C. In winter, the early morning temperature can drop below 5°C, while in summer, the temperature of a sunny slope exposed to direct sunlight can easily exceed 50°C. Within such a wide range of temperature variations, the actual catalytic activity of urease may decrease from its peak level to less than 20% or even lower. However, the spraying volume calculation formula in the first embodiment does not introduce any temperature-based correction factor for enzyme activity. This is equivalent to adding the cementing solution according to the ideal reaction efficiency at the optimum temperature under all temperature conditions. This will lead to two extreme consequences: under low-temperature or high-temperature construction conditions, a large amount of sprayed cementing solution cannot be effectively converted into calcium carbonate due to insufficient enzyme activity, resulting in material waste and a reinforcement effect far below design expectations; conversely, when approaching the optimum temperature, if a reverse adjustment is needed in the future, there is a lack of a corresponding reduction mechanism.

[0037] The second shortcoming lies in the fact that the reaction conversion rate is constrained by the slope-retention time coupling effect, which is not taken into account. Even under temperature conditions where urease has sufficient activity, the actual conversion rate of urea hydrolysis in porous media... It is not a constant value that can be preset, but is affected by the effective residence time of the cementitious liquid in the pores. Strong constraints. For the horizontal plane ( Soil tests on the soil showed that after the cementing liquid was sprayed, it could penetrate vertically into the pores under the action of gravity and remain there, allowing for sufficient reaction time.

[0038] However, the essential characteristic of slope construction is precisely that the slope surface is inclined, and the slope of engineering soil slopes can reach... Even steeper. On sloping slopes, the tangential component of gravity along the slope drives the cementitious liquid to flow laterally and run off along the slope while it seeps into the pores. The steeper the slope, the more significant this dispersal effect, and the shorter the effective residence time of the cementitious liquid per unit volume of soil. A shortened residence time means that the substrate has migrated downstream with the liquid before the enzyme-catalyzed reaction has fully occurred, leading to incomplete local reactions. The first embodiment uses liquid saturation... Setting a fixed empirical value range (60%-80%) is essentially based on the conditions of a horizontal test and cannot reflect the combined reduction effect of temperature fluctuations and liquid loss on the reaction conversion efficiency in a real steep slope environment.

[0039] The third drawback is the spatial unpredictability and uncontrollability of the effective calcium carbonate precipitation amount caused by the superposition of the two effects mentioned above. Since enzyme activity is a non-linear function of temperature, and the effective retention time is a function of slope, the actual mass of calcium carbonate produced... It becomes an implicit function of temperature field and slope distribution, and its distribution law in slope space and soil depth direction cannot be guaranteed by the original fixed volume formula.

[0040] More seriously, actual slopes exhibit significant spatial heterogeneity, with temperature differences exceeding 10°C between the sun-facing and shaded sides, and variations in slope gradient between the top and bottom. This results in significant spatial fluctuations in calcium carbonate precipitation even within the same soil layer from the same construction batch. The uneven distribution of calcium carbonate directly leads to uncontrollable gradient changes in the mechanical strength and saturated permeability coefficient of the solidified soil layer along both depth and plane: insufficiently reinforced areas become weak permeability channels, preferentially breached during rainfall infiltration. This fundamentally undermines the prerequisite of a uniform, low-permeability layer upon which capillary resistance relies, making it impossible to reliably achieve the core design goal of uniform calcium carbonate precipitation along soil depth, as pursued in the first embodiment, during actual slope construction.

[0041] In summary, the core deficiency of the first embodiment can be attributed to the fact that its spray volume calculation model only solves the geometric problem of how much liquid needs to be injected to fill the pores, but completely fails to answer the chemical kinetic problem of how much of the injected liquid can actually be converted into calcium carbonate under specific temperature and slope conditions. This disconnect constitutes a fundamental adaptation gap from ideal laboratory conditions to the complex environment of an engineering site. To address this adaptation gap between the spray volume calculation model in the first embodiment and actual enzyme reaction kinetics, this improved mechanism superimposes a closed-loop adaptive control system across the entire chain of temperature, enzyme activity, slope retention, reaction conversion rate, and spray volume onto the original geometric pore-filling model.

[0042] Specifically, in this embodiment, step S4.2 includes: S4.2a, acquiring the surface temperature of the physically compacted monolayer using an embedded thermocouple or infrared thermometer to obtain the real-time slope temperature, and determining the enzyme activity correction coefficient based on the real-time slope temperature; S4.2b, constructing a slope retention time reduction coefficient based on the porosity and layer thickness of the physically compacted monolayer, combined with the slope inclination angle, coupling the enzyme activity correction coefficient and the slope retention time reduction coefficient as a product factor and substituting them into a first-order reaction kinetic model to obtain the effective conversion rate, and then using the effective conversion rate to perform reverse compensation correction on the original geometric pore-filling spray volume to obtain the adaptive spray volume; S4.2c, dividing the physically compacted monolayer into several construction zones along the slope direction, independently calculating the adaptive spray volume of each construction zone based on the local temperature and local slope of each construction zone, and using a pressure spraying device to perform zoned gradient spraying of the cementing liquid according to the adaptive spray volume corresponding to each construction zone.

[0043] More specifically, in step S4.2a, the surface temperature of the physically compacted monolayer is collected using an embedded thermocouple or infrared thermometer to obtain the real-time slope temperature, and an enzyme activity correction coefficient is determined based on the real-time slope temperature. It should be understood that, as a protein biocatalyst, urease's three-dimensional conformation is extremely sensitive to temperature, and its catalytic activity exhibits a typical bell-shaped curve characteristic with temperature changes. In the low-temperature region, the thermal motion energy of the enzyme molecules is insufficient to efficiently drive the formation of the substrate-enzyme complex, resulting in low catalytic activity. Activity gradually increases with increasing temperature, reaching a peak at the optimum temperature of approximately 37°C. However, once the optimum temperature is exceeded, irreversible thermal denaturation of the protein occurs, and peptide chain unfolding leads to permanent destruction of the active sites, resulting in a sharp loss of catalytic ability. Slope construction operations span different seasons and day-night cycles, and the actual temperature of the slope surface can fluctuate drastically between 5°C and 55°C. In winter, early morning temperatures can drop below 5°C, while in summer, the temperature of sunny slopes exposed to direct sunlight can easily exceed 50°C. Within such a wide range of temperature variations, the actual catalytic activity of urease may decrease from its peak level to less than 20% or even lower. The spraying volume calculated based on the aforementioned geometric pore-filling model does not incorporate any temperature-based correction factor for enzyme activity. This is equivalent to applying the cementing solution according to the ideal reaction efficiency at the optimal temperature under all temperature conditions. This will result in a large amount of cementing solution sprayed under low-temperature or high-temperature construction conditions not being effectively converted into calcium carbonate due to insufficient enzyme activity, leading to material waste and reinforcement effects far below design expectations. Therefore, in the technical solution of this application, the surface temperature of the physically compacted monolayer is collected using an embedded thermocouple or infrared thermometer to obtain the real-time slope temperature. Based on the real-time slope temperature, an enzyme activity correction coefficient is determined to establish a mathematical model that can quantitatively map the real-time ambient temperature to the degree of reduction in enzyme catalytic efficiency. This provides a temperature-dimensional correction basis for subsequent reaction conversion rate calculations, enabling the spraying volume decision to have an enzyme kinetic basis that strictly corresponds to the actual construction temperature environment for the first time. This eliminates the prediction deviation of reaction efficiency caused by temperature fluctuations, ensuring that the amount of cementing solution added can be dynamically adjusted according to the actual enzyme activity level under different seasons and diurnal temperature differences. This avoids the problem of insufficient calcium carbonate precipitation or waste of raw materials due to insufficient enzyme activity under low or high temperature conditions, and lays a data foundation for the accurate and controllable amount of calcium carbonate precipitation.

[0044] Specifically, in a particular example of this application, the surface temperature of the physically compacted monolayer is collected by an embedded thermocouple or an infrared thermometer to obtain the real-time slope temperature. Five to eight temperature measuring points are evenly distributed along the slope direction on the surface of the physically compacted monolayer. The location of each measuring point is selected in a representative location of the construction area, including different areas such as the sunny side, the shady side, the top of the slope, the middle of the slope, and the bottom of the slope, to ensure that the temperature collection can reflect the temperature distribution characteristics of the slope. Temperature data was collected at each measuring point using a type K thermocouple or an infrared thermometer with an accuracy of ±0.5℃. The type K thermocouple has a measuring range of -200℃ to 1300℃ and a response time of 1 to 3 seconds. The thermocouple's sensing end was inserted 5mm to 10mm below the surface of the physically compacted monolayer, ensuring the measuring point was inside the soil and not in the air. The infrared thermometer has a measuring range of -50℃ to 800℃, with a measurement distance to target diameter ratio of 12:1. The infrared thermometer was positioned perpendicularly to the physically compacted monolayer surface, with a measurement distance controlled between 0.5m and 1.0m. Measurements were taken at intervals of 5 to 10 minutes, and the average value of 3 to 5 measurements was taken as the real-time slope temperature T (unit: ...). To eliminate the influence of instantaneous temperature fluctuations, the real-time slope temperature T was measured to be 28℃.

[0045] Based on real-time slope temperature, an enzyme activity correction coefficient was determined. Given the inherent asymmetric thermal response characteristics of urease as a protein catalyst, the gradual activation process in the low-temperature region and the irreversible thermal denaturation and inactivation process in the high-temperature region have fundamentally different kinetic mechanisms. A piecewise asymmetric function model was constructed to map enzyme activity to real-time slope temperature. When the real-time slope temperature T does not exceed the optimal reaction temperature Topt of urease, the enzyme is in the temperature-increasing activation region, and a Gaussian rising model is used to describe the gradual increase in activity with temperature. When T exceeds... At this point, the enzyme is in the thermal denaturation and inactivation region. An exponential decay model is used to describe the rapid loss of activity due to protein conformational disruption. The two function segments are concatenated at Topt and normalized to a peak value of 1 to obtain a dimensionless enzyme activity correction coefficient. , means as follows: in, This is the enzyme activity correction factor, dimensionless, with a value range of (0, 1]. This indicates that urease is in a fully catalytically active state at the optimal temperature; T is the real-time slope temperature in degrees Celsius. The optimal reaction temperature for urease is expressed in degrees Celsius; the reference value in the literature is 37°C. The low-temperature activation broadening factor, in degrees Celsius, characterizes the degree to which the activity of urease decreases with decreasing temperature below the optimum temperature. The larger the value, the wider the enzyme's tolerance range to low temperatures. It is usually taken as 10~15°C. This is the high-temperature inactivation attenuation factor, expressed in degrees Celsius. It characterizes the rate at which urease loses its catalytic ability due to protein denaturation. A smaller value indicates faster high-temperature inactivation; typically, it is taken as 8–12°C. When T is less than or equal to... The first Gaussian rising model is used, and the exponent term of the exp function on the right side of the formula is negative (T minus...). Squared by 2 This exponential term characterizes the inhibitory effect of temperature deviation from the optimum temperature on enzyme activity. The greater the temperature deviation, the larger the absolute value of the exponential term, the smaller the exp function value, and the lower the enzyme activity. In the low-temperature region, the decrease in urease activity stems from insufficient molecular thermal energy, leading to a reduced rate of substrate-enzyme complex formation. This is a reversible process; enzyme activity can recover when the temperature rises back to the optimum temperature. The parameter controls the rate of activity decay at low temperatures; a higher value indicates that the enzyme maintains higher activity at low temperatures and has stronger tolerance to low temperatures. When T is greater than... When using the second-stage exponential decay model, the exponential term of the exp function on the right side of the formula is negative (T minus...). Divide by This exponential term characterizes the destructive effect of thermal denaturation on enzyme activity after the temperature exceeds the optimum temperature. The higher the temperature exceeds the optimum temperature, the larger the absolute value of the exponential term, the smaller the exp function value, and the lower the enzyme activity. In the high-temperature region, the loss of urease activity stems from the irreversible destruction of protein peptide chain unfolding and active sites. This is an irreversible process, and enzyme activity cannot be restored even if the temperature is lowered. The parameter controls the rate of activity decay at high temperatures. The smaller the value, the faster the enzyme is inactivated at high temperatures and the worse its tolerance to high temperatures.

[0046] This step employs a piecewise asymmetric model instead of the symmetric Gaussian distribution or simple Arrhenius equation commonly used in traditional enzymology. Traditional symmetric models assume that the enzyme's activity decay rate is the same on both sides of the optimum temperature. However, the decrease in urease activity at low temperatures stems from insufficient molecular thermal energy, a reversible process, while the loss of activity at high temperatures results from irreversible destruction of the protein peptide chain and active site. The physicochemical mechanisms of these two processes are fundamentally different, and their decay rates also differ significantly. The piecewise asymmetric model addresses this by setting independent broadening parameters for each process. and attenuation parameters This accurately captures the asymmetry, enabling the model to provide reliable active correction outputs across a wide temperature fluctuation range of 5°C to 55°C in slope construction scenarios. The real-time slope temperature T is set to 28°C, and the optimal reaction temperature for urease is... Equal to 37℃, low temperature side activation broadening factor Substituting 12℃ into the first formula, we can calculate the enzyme activity correction coefficient. The equation is equal to the square of negative exp(28 minus 37) divided by 2 multiplied by the square of 12, which is equal to the square of negative exp(81) divided by 288, which is equal to the square of negative exp(0.281), which is equal to 0.755. This result indicates that under the real-time slope temperature of 28℃, the actual catalytic activity of urease is only 75.5% of that at the optimal temperature of 37℃. Compared with the fully active state under ideal conditions, there is a 24.5% efficiency loss. If the spray volume is not compensated accordingly, the amount of calcium carbonate precipitation will be lower than the design target value.

[0047] More specifically, in step S4.2b, based on the porosity and layer thickness of the physically compacted single layer, a slope retention time reduction coefficient is constructed in combination with the slope inclination angle. The enzyme activity correction coefficient and the slope retention time reduction coefficient are coupled as product factors and substituted into the first-order reaction kinetic model to obtain the effective conversion rate. Then, the original geometric pore filling spray volume is reverse-compensated and corrected with the effective conversion rate to obtain the adaptive spray volume. It is understandable that the aforementioned steps only yielded an enzyme activity correction coefficient, which reflects only the effect of temperature on urease catalytic efficiency. However, even under temperature conditions where urease has sufficient activity, the actual conversion rate of urea hydrolysis in porous media is not a constant value that can be preset. Instead, it is strongly constrained by the effective residence time of the cementing solution in the pores. For soil tests on horizontal surfaces, the cementing solution can vertically penetrate and remain in the pores under gravity after spraying, providing sufficient reaction time. However, the essential characteristic of slope construction scenarios is precisely that the slope is inclined. Since the slope of engineering soil slopes can reach 45 degrees or even steeper, on inclined slopes, the tangential component of gravity along the slope will drive the cementing solution to penetrate into the pores while simultaneously moving along the slope direction. Lateral flow and loss occur, and the greater the slope, the more significant the displacement effect. The effective residence time of the cementing liquid in a unit soil volume is shorter. The shortened residence time means that the reaction substrate has migrated to the downstream area with the liquid before the enzyme catalytic reaction has been fully carried out, resulting in incomplete local reaction. Temperature correction alone, without slope correction, cannot fully describe the conversion efficiency under actual reaction conditions. At the same time, the spray volume calculated based on the geometric pore filling model only solves the geometric problem of how much liquid needs to be injected to fill the pores, but it does not answer the chemical kinetic problem of how much of the injected liquid can actually be converted into calcium carbonate under specific temperature and slope conditions. The disconnect between the two constitutes a fundamental adaptation gap from ideal conditions to the complex environment of the engineering site. Therefore, in the technical solution of this application, a slope residence time reduction coefficient is further constructed based on the porosity and layer thickness of the physically compacted single layer combined with the slope inclination. The enzyme activity correction coefficient and the slope residence time reduction coefficient are coupled as product factors and substituted into the first-order reaction kinetic model to obtain the effective conversion rate. Then, the original geometric pore-filling spray volume is reverse-compensated and corrected with the effective conversion rate to obtain the adaptive spray volume. In this way, the enzyme activity correction in the temperature dimension and the residence time reduction in the slope dimension are coupled to construct a comprehensive conversion rate model that can simultaneously reflect the two effects. Based on this, the spray volume is reverse-compensated and corrected. The enzyme activity temperature correction and the slope residence time reduction are embedded as product factors into the first-order reaction kinetic framework to construct a temperature-slope-reaction rate ternary coupled effective conversion rate model, so that the cementing liquid input amount is transformed from a fixed empirical value based on idealized assumptions to a dynamic optimal solution based on real-time environmental conditions.This ensures that the effective precipitation amount of calcium carbonate in each layer can reach the same design target value as under ideal conditions under any combination of temperature and slope. When the actual conversion rate is lower than the reference value due to low temperature or steep slope, the adaptive spraying volume automatically increases to add more reaction substrate to compensate for the efficiency loss. Conversely, when the conditions are close to ideal, the adaptive spraying volume automatically approaches the original volume to avoid waste of raw materials and runoff pollution caused by excessive spraying. This eliminates the deviation in reaction efficiency prediction caused by temperature fluctuations and slope changes, and ensures the precise control of calcium carbonate precipitation.

[0048] Specifically, in a concrete example of this application, a slope retention time reduction factor is constructed based on the porosity and layer thickness of a physically compacted single layer, combined with the slope inclination angle. After the cementitious liquid is sprayed onto the inclined slope, the tangential component of gravity along the slope direction drives the liquid to flow laterally along the slope. The greater the slope, the stronger the driving force, and the shorter the effective retention time of the liquid in the target area. Based on this physical mechanism, the slope inclination angle is introduced. Construct a slope residence time reduction factor : in, This is the slope residence time reduction factor, dimensionless, with a value range of (0, 1). The corresponding horizontal plane is The ideal situation; The slope angle is expressed in degrees or radians. The flow sensitivity coefficient is a dimensionless empirical parameter that reflects the ability of the compacted soil's pore structure to impede gravity-driven seepage. The finer the pores and the poorer the connectivity, the lower the flow sensitivity coefficient. The smaller the value, the more likely it is to be between 1.5 and 3.0. The contribution of the tangential component of the gravitational field along the slope to the liquid displacement effect was directly quantified. The term characterizes the influence of the slope inclination angle on the tangential component of gravity, directly quantifying the contribution of the gravitational field along the slope tangential component to the liquid displacement effect. A larger slope inclination angle results in a larger sinθ, a larger denominator, and a smaller β(θ), indicating a shorter liquid residence time. With a slope inclination angle θ equal to 30 degrees and a flow sensitivity coefficient... Substituting 2.0 into the formula, the slope residence time reduction factor is calculated. The result is equal to 0.500, which indicates that under a slope angle of 30 degrees, the effective residence time of the cementitious liquid in the soil pores is 50.0% of that under horizontal conditions.

[0049] Based on this, the enzyme activity correction factor Slope residence time reduction factor Substrate conversion is coupled into the first-order reaction kinetic model as a product factor to obtain the effective conversion rate. In enzyme-catalyzed reactions, the substrate conversion rate exhibits an exponentially decreasing relationship with the product of the effective reaction rate constant and the reaction time. The effective reaction rate constant is proportional to the enzyme activity, and the effective reaction time is proportional to the liquid residence time. and As a joint reduction factor to the standard rate constant, the effective conversion rate coupled with temperature and slope is constructed. Model: in, The effective urea hydrolysis conversion rate is dimensionless and characterizes the actual proportion of urea converted into calcium carbonate under actual temperature and slope conditions. The theoretical maximum conversion rate is dimensionless and is determined by both the stoichiometric ratio and the purity of urease, typically ranging from 0.85 to 0.95. For standard conditions (i.e.) and The apparent first-order reaction rate constant under the given conditions is expressed in min. −1 ; The standard reference residence time, in minutes, is determined by the permeability characteristics of the porous medium. The first term on the right-hand side of the formula... The theoretical maximum conversion rate is determined by both the stoichiometry and the purity of urease. The second term, 1 minus the exp function, characterizes the gradual saturation of the reaction conversion rate over time; the exponential term of the exp function is negative. Multiply Multiply Multiply ,in The apparent first-order reaction rate constant under standard conditions. This is the enzyme activity correction factor. This is the slope residence time reduction factor. The product of the three is the standard reference dwell time. Characterizing the effective reaction time equivalent under actual temperature and slope conditions, when the temperature deviates from the optimum value. Decrease when the slope increases The product effect of these two factors causes the effective rate constant to decay synchronously, leading to a decrease in conversion rate. This coupled response mechanism is precisely the physicochemical cross-effect that was completely omitted in the first embodiment. The theoretical maximum conversion rate... Equal to 0.90, standard reaction rate constant Equal to 0.05 min⁻¹, enzyme activity correction factor Equal to 0.755, slope residence time reduction factor Equal to 0.500, standard reference residence time Substituting 60 minutes into the formula, the effective conversion rate is calculated. The result is equal to 0.610, indicating that under the actual construction conditions of a real-time slope temperature of 28℃ and a slope inclination of 30 degrees, the effective hydrolysis conversion rate of urea is only 61.0%, which is significantly lower than the 85.5% under the standard ideal conditions.

[0050] Furthermore, to ensure that the effective precipitation amount of calcium carbonate in each layer can reach the ideal condition under any combination of temperature and slope (…), and To achieve the same design target value, the spray volume needs to be corrected by reverse compensation based on the conversion rate difference. Therefore, the original geometric pore-filling spray volume is corrected by reverse compensation using the effective conversion rate to obtain an adaptive spray volume. Let the reference conversion rate be... Calculated under standard ideal conditions The value indicates the corrected adaptive spray volume. for: in, The spray volume is the adaptively corrected volume, in cubic meters. The reference conversion rate, i.e., the value calculated by the above conversion rate formula under standard ideal conditions, is used as the normalization benchmark. The effective conversion rate under actual conditions; The paved area is in square meters. The thickness of a single layer after compaction is taken as 0.1 meters; Porosity of compacted soil, dimensionless; To design the liquid saturation, a value of 0.6 to 0.8 is used. The formula structure clearly reflects the adaptive compensation logic, and the molecules... This represents the volume of pores that need to be filled with binder in a physically compacted single layer, multiplied by The effective reaction volume equivalent under ideal conditions is represented by the denominator. The actual conversion efficiency represents the conversion efficiency under real-world conditions. Dividing the two values ​​yields the actual spray volume required to compensate for the efficiency gap. When the actual conversion rate is lower than the reference value due to low temperature or steep slope... Automatically increasing the amount of reactant added to compensate for efficiency loss, and conversely, when conditions are close to ideal... The system automatically approximates the original volume to avoid material waste and runoff pollution caused by excessive spraying. The paving area A is equal to 50m², and the single-layer thickness after compaction is... Equal to 0.1m, soil porosity n after compaction equals 0.30, design fluid saturation. Equal to 0.70, effective conversion rate Equal to 0.610, reference conversion rate Substituting 0.855 into the formula yields 1471L.

[0051] More specifically, in step S4.2c, the physically compacted single layer is divided into several construction zones along the slope direction. The adaptive spraying volume of each construction zone is independently calculated based on the local temperature and local slope of each construction zone. The cementing liquid is sprayed in a zone gradient according to the adaptive spraying volume corresponding to each construction zone using a pressure spraying device. It is understandable that the adaptive spraying volume output by the aforementioned steps is a single value calculated based on the overall average temperature and uniform slope of the slope. However, the actual slope surface exhibits significant spatial heterogeneity, with the temperature difference between the sunny and shady sides reaching over 10℃. The local slope at the top and bottom of the slope may also vary due to topographical undulations. If spraying is still carried out uniformly across the entire layer, there may be over-spraying in the sunny, high-temperature areas and under-spraying in the shady, low-temperature areas. This results in significant spatial fluctuations in the amount of calcium carbonate precipitation in different areas of the same soil layer within the same construction batch. The uneven distribution of calcium carbonate will directly lead to uncontrollable gradient changes in the mechanical strength and saturated permeability coefficient of the solidified soil layer along the depth and plane directions. Areas with insufficient reinforcement become weak permeability channels that are preferentially breached during rainfall infiltration, fundamentally undermining the premise of a uniform, low-permeability layer upon which the capillary repression effect depends. Furthermore, the aforementioned steps only complete the theoretical calculation of the spraying volume and lack a verification and feedback mechanism for the actual mineralization effect, making it impossible to ensure that the calculated adaptive spraying volume can truly achieve the expected calcium carbonate precipitation target in actual construction. Therefore, in the technical solution of this application, the physically compacted single layer is further divided into several construction zones along the slope direction. Based on the local temperature and local slope of each construction zone, the adaptive spraying volume of each construction zone is independently calculated. The cementing liquid is sprayed in a gradient according to the adaptive spraying volume corresponding to each construction zone using a pressure spraying device. After spraying is completed and sufficient reaction curing is performed, samples are taken from each construction zone and the actual amount of calcium carbonate precipitation is detected by rapid acid washing titration. The deviation is compared with the design target precipitation amount to calculate the uniformity deviation of each construction zone. When the uniformity deviation of a construction zone exceeds the preset allowable threshold, the area needs to be sprayed again or cumulatively compensated during the construction of subsequent layers. In this way, the distribution accuracy of cementing liquid is improved from uniformity of the whole layer to adaptive distribution of each zone in the spatial dimension, which accurately eliminates the risk of uneven mineralization caused by slope temperature gradient and slope heterogeneity. At the same time, by introducing a feedback correction loop of spraying-detection-deviation assessment-compensation, the entire mineralization process is upgraded from an open-loop one-time input to a closed-loop input-verification-correction iterative control.This ensures that the spatial distribution uniformity of calcium carbonate precipitation across the entire slope meets the design tolerance requirements, fundamentally eliminating the risk of weak permeability channels due to insufficient local mineralization. It guarantees the functional integrity and long-term service reliability of the solidified soil layer as a low-permeability core barrier in the capillary retardation system. At the same time, the zoned gradient spraying strategy improves the distribution accuracy of the cementing liquid from uniform distribution across the entire layer to adaptive distribution across each zone. By introducing a feedback correction loop of spraying-detection-deviation assessment-compensation, the quality control of the mineralization process is refined from the entire layer level to the zone level, upgrading from an open-loop one-time input to a closed-loop iterative correction control. This refines the granularity of quality control during construction from the layer level to the zone level.

[0052] Specifically, in a particular example of this application, the physically compacted monolayer is divided along the slope direction into The number of construction zones is determined based on the slope temperature gradient and slope heterogeneity characteristics. The area of ​​each construction zone is denoted as ( The sum of the areas of all zones equals the total paved area A. Local temperatures were collected for each construction zone. and local slope ,Will and Substitute the formula chains from steps M1 and M2 independently to calculate the local enzyme activity correction coefficient for each construction zone. Local slope retention reduction coefficient and local effective conversion rate This allows for the obtaining of independent corrected spraying volumes for each construction zone. : in, For the first The adaptive correction spraying volume for each construction zone, in cubic meters; For the first The area of ​​each construction zone, in square meters; For the first Each construction zone is based on local temperature. and local slope The calculated effective conversion rate is dimensionless. An equimolar binder is applied using a pressure spray system according to the corresponding application zones. Precision spraying with gradients in zones allows the cementing solution to penetrate the pores of the physically compacted monolayer and come into contact with premixed dry sword bean powder (urease source). Under the catalysis of urease, urea hydrolysis occurs to generate carbonate ions. The carbonate ions react with calcium ions at the contact points of soil particles to form calcium carbonate precipitation and cement bridges.

[0053] For example, for a physically compacted single layer with a paving area A of 50m² in the construction area, considering the temperature difference between the sunny and shady sides and the slope changes between the top and bottom of the slope, the physically compacted single layer is divided into 4 construction zones along the slope direction. ( The areas of each construction zone are A1 (12m²), A2 (13m²), A3 (12m²), and A4 (13m²), respectively. The sum of the areas of all zones equals the total paving area A, which is 50m². Local temperatures were collected for each construction zone. and local slope Temperature measurement points were set up in the first construction zone using K-type thermocouples for temperature acquisition. The measurement interval was 5 to 10 minutes, and the average value was taken after 3 to 5 consecutive measurements as the local temperature of the first construction zone. , measured The slope is equal to 25°C. A digital inclinometer or total station is used to measure the slope angle of the first construction zone. Three to five representative locations within the zone are selected for slope measurement, and the average value is taken as the local slope of the first construction zone. , measured It equals 28 degrees. and Substitute the formula chains from steps S4.2a and S4.2b independently to calculate the local enzyme activity correction coefficient for the first construction zone. Local slope retention reduction coefficient and local effective conversion rate Local temperature Equal to 25℃, the optimal reaction temperature of urease Equal to 37℃, low temperature side activation broadening factor Substituting 12℃ into the enzyme activity correction coefficient formula, the local enzyme activity correction coefficient is calculated. It equals the square of negative exp(25 minus 37) divided by 2 multiplied by the square of 12, which equals the square of negative exp(144) divided by 288, which equals the square of negative exp(0.5), which equals 0.606. Given a local slope θ1 of 28 degrees and a flow sensitivity coefficient... Substituting 2.0 into the slope residence time reduction formula, and setting the theoretical maximum conversion rate αmax to 0.90, the standard reaction rate constant k0 to 0.05 min⁻¹, and the local enzyme activity correction factor... Equal to 0.917, local slope retention reduction factor Substituting 0.516 and the standard reference residence time t0 equal to 60 min into the effective conversion rate formula, the local effective conversion rate α of the first construction zone is calculated. eff 1 equals 0.683. Therefore, the independent corrected spraying volume V for the first construction zone is obtained. spray, 1, A1 is the area of ​​the first construction zone, which is equal to 12m². The compacted layer thickness is 0.1m, and n represents the compacted soil porosity of 0.30. To design the liquid saturation to be equal to 0.70, The effective conversion rate calculated for the first construction zone based on local temperature T1 and local slope θ1 is 0.683. The reference conversion rate is 0.855.

[0054] Furthermore, the above-mentioned temperature acquisition, slope measurement, enzyme activity correction coefficient calculation, slope retention reduction coefficient calculation, effective conversion rate calculation, adaptive spraying volume calculation, and zone spraying process were repeated sequentially for the second, third, and fourth construction zones to complete the gradient spraying of all construction zones. After spraying was completed and sufficient reaction curing was performed, samples were taken from each construction zone, and the actual amount of calcium carbonate precipitation was determined using a rapid acid washing titration method. Compare it with the design target sedimentation amount Perform deviation comparison and calculate the uniformity deviation of each construction zone. : in, For the first The deviation of calcium carbonate precipitation uniformity in each construction zone is expressed as a percentage. For the first The mass of calcium carbonate precipitate in each construction zone was measured by acid washing titration, in grams; The target amount of calcium carbonate precipitate, calculated from the structural mechanical strength and permeability design requirements, is expressed in grams. When a certain construction zone... Exceeding the preset allowable threshold When the concentration of the coating layer is typically set at 15%, a second application of additional spraying or cumulative compensation during subsequent layer construction is required to eliminate weak points in the localized reinforcement. When the uniformity deviation across all construction zones... All meet When the mineralization quality of the layer is deemed acceptable, the mineralized single layer is output.

[0055] This step improves the engineering closed-loop nature of the improvement mechanism on two levels. Spatially, the zoned gradient spraying strategy enhances the distribution precision of the cementitious liquid from uniform distribution across the entire layer to adaptive distribution across zones, precisely mitigating the risks of uneven mineralization caused by slope temperature gradients and slope heterogeneity. In terms of quality control, by introducing a feedback correction loop of spraying → detection → deviation assessment → compensation, the entire mineralization process is upgraded from an open-loop, one-time input to a closed-loop input-verification-correction iterative control, ensuring the performance consistency of each layer of solidified soil in terms of factory inspection. It is particularly noteworthy that the uniformity deviation... The introduction of this method provides clear and quantifiable acceptance criteria for the construction site, replacing the crude acceptance mode in the first embodiment that relied on the post-event detection of the overall macroscopic permeability coefficient. This allows the granularity of quality control during the construction process to be refined from the layer level to the zone level.

[0056] Through this step of precise spraying in different zones and feedback correction based on actual measurements, the spatial distribution uniformity of calcium carbonate precipitation across the entire slope is ensured to meet the design tolerance requirements. This fundamentally eliminates the risk of weak permeability channels formed due to insufficient local mineralization, and guarantees the functional integrity and long-term service reliability of the solidified soil layer as a low-permeability core barrier in the capillary barrier system.

[0057] This improved mechanism achieves the following technical effects and objectives by systematically constructing a three-level progressive closed-loop control chain on top of the original geometric pore-filling spraying model: temperature-responsive enzyme activity correction → temperature-slope coupled conversion rate modeling and adaptive spraying volume calculation → zoned gradient spraying and feedback correction execution.

[0058] In terms of precise reaction efficiency, by introducing a segmented asymmetric enzyme activity correction function, the nonlinear catalytic efficiency fluctuation of urease in a wide temperature range of 5°C to 55°C was explicitly quantified and modeled. This enabled the spraying amount decision to have an enzyme kinetic basis that strictly corresponds to the actual construction temperature environment for the first time, eliminating the systematic conversion rate deviation caused by neglecting the temperature effect under extreme temperature conditions in the first embodiment.

[0059] In terms of multi-physics coupling adaptation, an effective conversion rate model with temperature-slope-reaction rate ternary coupling was constructed by embedding enzyme activity temperature correction and slope residence time reduction as product factors into the first-order reaction kinetics framework. Based on this model, the spraying volume was corrected by reverse compensation based on the conversion rate difference, so that the cementing liquid input amount was transformed from a fixed empirical value based on idealized assumptions to a dynamic optimal solution based on real-time environmental conditions. This ensures that the effective precipitation amount of calcium carbonate in each layer can consistently reach the design target value under different seasons, slopes and orientations.

[0060] In terms of ensuring spatial uniformity, the quality control of the mineralization process is refined from the whole layer level to the zone level through a zoned gradient spraying strategy and a measured feedback correction loop based on the uniformity deviation index. This upgrades the process from an open-loop, one-time input to a closed-loop iterative correction control, fundamentally eliminating local insufficient mineralization caused by slope temperature gradients and topographic heterogeneity. This ensures the spatial functional continuity and long-term seepage prevention reliability of the solidified soil layer as the core low-permeability barrier of the capillary barrier system.

[0061] Accordingly, in step S4.3, using the mineralized monolayer as the base, the paving, compaction, and spraying processes of steps S4.1 and S4.2 are repeated, layer by layer upwards, until the total thickness reaches 200mm-600mm, and the saturated permeability coefficient is tested to be less than 1×10⁻⁶. - 6 After reaching a speed of cm / s, a solidified soil layer is formed. It is understandable that the solidified soil layer needs to reach a total design thickness of 200mm to 600mm to meet the requirements of low permeability, water-blocking performance, and mechanical strength for the capillary repression capillary layer. However, a single compacted layer is only 100mm thick. If only one mineralized single layer is constructed, the required total design thickness cannot be achieved. Furthermore, as the core low-permeability barrier of the capillary repression system, the solidified soil layer's saturated permeability coefficient must be less than 1×10⁻⁶. -6 Only when the speed is cm / s can the saturated permeability coefficient of the underlying coarse-particle-guided layer be 1×10⁻⁶. -2 Up to 1×10 -1 The significant abrupt change in permeability coefficient (cm / s) creates an effective capillary resistance effect. However, without verifying the saturated permeability coefficient of the solidified soil layer, it's impossible to confirm whether it meets design requirements, potentially leading to the failure of the capillary resistance effect. Therefore, in this application's technical solution, using a mineralized monolayer as the base, the paving, compaction, and spraying processes of steps S4.1 and S4.2 are repeated, layer by layer upwards until the total thickness reaches 200mm to 600mm. The saturated permeability coefficient is then tested to be less than 1×100. -6 After reaching a speed of cm / s, a solidified soil layer is formed. This is achieved through multi-layered construction, gradually accumulating the total thickness of the solidified soil layer until the design requirements are met. Simultaneously, after all layers are constructed, the saturated permeability coefficient of the solidified soil layer is tested to confirm that its low-permeability water-blocking performance meets the technical indicators of capillary resistance. This ensures that both the total thickness and saturated permeability coefficient of the solidified soil layer meet the design requirements, forming a stable low-permeability water-blocking layer. Together with the underlying high-permeability drainage layer, this forms an effective capillary resistance structure, significantly improving the slope's seepage prevention performance and long-term stability.

[0062] More specifically, in a specific example of this application, the paving, compaction and spraying processes of steps S4.1 and S4.2 are repeated with the mineralized monolayer as the base surface. After the first mineralized monolayer is completed and fully cured, the first mineralized monolayer is used as the base surface for the second layer. 8500 kg of the second batch of mixed soil is evenly spread on the surface of the first mineralized monolayer and leveled. The mixed soil is transported to the surface of the first mineralized monolayer using a loader and laid from bottom to top along the slope direction. During the laying process, a scraper is used to scrape and level the mixed soil back and forth along the slope direction to spread the mixed soil into a paving layer of uniform thickness. The loose paving thickness is controlled between 110 mm and 120 mm. The paving layer is compacted using compaction machinery to a single layer thickness of 100 mm and a compaction degree of not less than 90%. A vibratory roller is used to compact the paving layer with a vibration frequency of 50 Hz and an amplitude of 0.5 mm. The roller is rolled at a uniform speed from bottom to top along the slope, with a rolling speed controlled between 1.5 m / min and 2.5 m / min. The number of compaction passes is 4 to 6, and the single layer thickness is 100 mm. After compaction, the dry density of the compacted layer is tested using the sand cone method to ensure that the compaction degree is not less than 90%, thus obtaining the second physically compacted single layer. The second physically compacted monolayer was divided into four construction zones along the slope. Local temperature and slope were collected for each zone, and the adaptive spraying volume for each zone was independently calculated. Using a pressure sprayer, 2400L of the second binder solution was sprayed in a gradient according to the adaptive spraying volume corresponding to each zone. This allowed the binder solution to penetrate the pores of the second physically compacted monolayer and contact the premixed dry broad bean powder. Under the catalysis of urease, urea underwent a hydrolysis reaction to generate carbonate ions. These carbonate ions react with calcium ions at the contact points of soil particles to form calcium carbonate precipitation, creating cement bridges and resulting in the second mineralized monolayer. Layers were then stacked upwards, using the second mineralized monolayer as a base, repeating the above paving, compaction, and spraying process until the total thickness reached 200mm to 600mm.

[0063] After all layers of construction were completed, the saturated permeability coefficient of the solidified soil layer was tested. The saturated permeability coefficient was determined using a double-ring infiltrator or a variable head permeability test. The specific operation of the double-ring infiltrator method involved selecting 3 to 5 representative locations on the surface of the solidified soil layer. At each location, a double ring (inner ring diameter 300mm, outer ring diameter 500mm) was pressed into the solidified soil layer to a depth of 20mm to 30mm below the surface. Clean water was simultaneously injected into both the inner and outer rings, maintaining a constant water head height of 50mm. The volume and time of water level drop in the inner ring were recorded. The saturated permeability coefficient was calculated using Darcy's law: saturated permeability coefficient equals the permeation volume divided by the inner ring area divided by the water head gradient divided by the permeation time. The average value of the 3 to 5 measuring points was taken as the saturated permeability coefficient of the solidified soil layer. The tested saturated permeability coefficient of the solidified soil layer was 8.6 × 10⁻⁶. -7 m / s, less than the design requirement of 1×10-6 cm / s, meeting the technical specifications for low-permeability water-blocking layers, forming a solidified soil layer.

[0064] Specifically, in step S5, before the final compaction of the solidified soil layer, herbaceous and woody plant seeds are sown at a set density 10mm below the surface of the uncompacted soil. After the seeds are fixed in place by compaction of this layer, a breathable and water-retaining green net is covered on the surface of the solidified soil layer and sprayed for maintenance to form a vegetation layer. It should be understood that although the solidified soil layer significantly improves the strength and impermeability of fine-grained soil through enzyme-induced calcium carbonate precipitation technology, resulting in a compaction degree of not less than 90% and a saturated permeability coefficient of less than 1×10⁻⁶, this process achieves the desired effect. -6 The solidified soil layer has a low permeability of cm / s, but it relies solely on the cementing and filling effects of calcium carbonate to improve its mechanical properties. During long-term service, it still faces the risk of surface soil loss due to rainfall erosion and the development of surface cracks caused by wet-dry cycles. Rainfall erosion will gradually erode the soil particles and calcium carbonate cement on the surface of the solidified soil layer, resulting in a decrease in the thickness of the solidified soil layer and an increase in surface roughness. Wet-dry cycles will generate shrinkage cracks on the surface of the solidified soil layer. These cracks will become the preferred channels for rapid rainwater infiltration on steep slopes, breaking through the capillary barrier layer. At the same time, the surface of the solidified soil layer lacks vegetation cover, and raindrops directly impacting the soil surface will produce a splash erosion effect. The kinetic energy of the raindrops will disperse the surface soil particles and transport them away with surface runoff, accelerating the erosion and degradation of the solidified soil layer. If a vegetation protection layer is not established on the surface of the solidified soil layer, the long-term stability and protective effect of the solidified soil layer will be greatly reduced. Therefore, in the technical solution of this application, before the final compaction of the solidified soil layer, herbaceous plant seeds and woody plant seeds are sown at a set sowing density at a depth of 10mm below the surface of the uncompacted soil. After the seeds are buried and fixed as the layer is compacted, a breathable and water-retaining green net is covered on the surface of the solidified soil layer and sprayed for maintenance to form a vegetation layer. In this way, through the biological reinforcement effect of the vegetation roots and the raindrop buffering effect of the above-ground parts, a structural seepage prevention-ecological protection composite system is constructed in synergy with the solidified soil layer. The vegetation roots form a root network in the soil, which tightly entangles and connects soil particles and calcium carbonate cement, significantly improving the tensile strength and shear strength of the solidified soil layer. The stems and leaves of the above-ground parts of the vegetation cover the soil surface, reducing the kinetic energy of raindrops and slowing down the surface runoff velocity, effectively preventing raindrop splash erosion and runoff scouring. At the same time, the transpiration of the vegetation can reduce the moisture content of the surface layer of the solidified soil layer and reduce the development of shrinkage cracks caused by the wet-dry cycle. In this way, the synergistic effect of the vegetation layer and the solidified soil layer can significantly improve the slope cover layer's resistance to rainfall erosion and the ability to resist deterioration by wet and dry cycles, ensuring the long-term stability of the solidified soil layer and the continuous effectiveness of the capillary resistance effect, while achieving ecological restoration and landscape beautification of the slope.

[0065] Figure 4This is a flowchart of step S5 of the construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergy slope cover layer according to an embodiment of this application. Figure 4 As shown, step S5 includes: S5.1. During the final layer construction of the solidified soil layer, a portion of mixed soil is laid on the mineralized underlying layer and kept uncompacted. Bahia grass seeds, Bermuda grass seeds, tall fescue seeds, and pigweed seeds are evenly sown on the surface of the uncompacted soil at a sowing density of 10g / m² each, to obtain a seed-containing preparatory layer; S5.2. The seed-containing preparatory layer is compacted to a single layer thickness of 100mm, so that the seeds are buried 10mm below the surface of the solidified soil layer as the soil is compressed. After compaction, the remaining portion of cementing liquid is evenly sprayed onto the compacted surface for surface mineralization sealing treatment; S5.3. The surface of the solidified soil layer is covered with a breathable and water-retaining green net and anchored with fasteners. The slope is continuously sprayed with water at a rate of 3mm / day for 14 days to promote seed germination and seedling growth, forming a vegetation layer.

[0066] More specifically, in a specific example of this application, during the final layer construction of the solidified soil layer, a portion of mixed soil is laid on the already mineralized underlying layer and kept uncompacted. Based on the design total thickness of the solidified soil layer being 200mm and the single-layer compaction thickness being 100mm, the number of construction layers is determined to be 2. After the first mineralized single-layer construction is completed, 8500kg of the second portion of mixed soil is taken as the paving material for the final layer. A loader is used to transport the mixed soil to the surface of the first mineralized single-layer and lay it from bottom to top along the slope direction. During the laying process, a scraper is used to scrape and level the mixed soil back and forth along the slope direction to spread it into a paving layer of uniform thickness. The loose paving thickness is controlled between 110mm and 120mm. After the paving is completed, it is kept uncompacted and no compaction operation is performed. Bahia grass seeds, Bermuda grass seeds, tall fescue seeds, and dung bean seeds were evenly sown on the surface of the uncompacted soil at a sowing density of 10 g / m². Bahia grass is a warm-season herbaceous plant with a well-developed root system and strong drought resistance. Bermuda grass is a warm-season herbaceous plant that grows rapidly and is resistant to trampling. Tall fescue is a cool-season herbaceous plant with strong cold resistance and a deep root system. Dung bean is a leguminous shrub with nitrogen-fixing ability and a well-developed root system. The mixed sowing of the four plants can achieve synergy between herbaceous and woody plants and complementarity between warm-season and cool-season plants, thereby improving the stability and resilience of vegetation cover.

[0067] The sowing operation was carried out manually. The operator held a seed bag and walked at a constant speed along the slope from bottom to top, sowing the seeds evenly on the surface of the uncompacted soil as he walked. The sowing density was controlled at 10g / m² for Bahia grass seeds, 10g / m² for Bermuda grass seeds, 10g / m² for tall fescue seeds, and 10g / m² for pigweed seeds, with a total sowing density of 40g / m². After sowing, a light rake was used to gently rake the surface of the uncompacted soil, so that the seeds were embedded 5mm to 10mm below the soil surface, preventing the seeds from being exposed on the soil surface and being blown away by the wind or washed away by rainwater, thus creating a seed-bearing preparatory layer. The seed-bearing preparatory layer is compacted to a single layer thickness of 100mm, burying the seeds 10mm below the surface of the solidified soil layer as the soil is compressed. A vibratory roller is used to compact the seed-bearing preparatory layer, with the vibration frequency set to 50Hz and the amplitude set to 0.5mm. The roller is rolled at a uniform speed from bottom to top along the slope, with a speed controlled between 1.5m / min and 2.5m / min, and 4 to 6 compaction passes are made. During the compaction process, the soil thickness is gradually compressed from a loose thickness of 110mm to 120mm to 100mm, and the soil surface decreases by 10mm to 20mm. The seeds, which were originally located 5mm to 10mm below the soil surface, are further buried to a depth of 10mm below the surface of the solidified soil layer as the soil is compressed. This depth is the optimal depth for plant seed germination, ensuring that the seeds receive sufficient water and oxygen while preventing them from failing to germinate due to being buried too deep or from being damaged by drought or erosion due to being buried too shallow.

[0068] After compaction, the remaining portion of cementitious liquid is evenly sprayed onto the compacted surface for surface mineralization sealing treatment. The second portion of cementitious liquid, 2400L, is then sprayed in a gradient according to the adaptive spraying volume corresponding to each construction zone, allowing the cementitious liquid to penetrate into the pores of the seed preparation layer and come into contact with the premixed dry sword bean powder. Under the catalysis of urease, urea undergoes a hydrolysis reaction to generate carbonate ions. The carbonate ions and calcium ions react at the contact points of soil particles to form calcium carbonate precipitation, creating cement bridges. This forms a certain strength erosion-resistant shell on the surface of the solidified soil layer. This shell can effectively resist rainfall erosion and runoff scouring, while not hindering the germination of plant coleoptiles through the soil layer. A breathable and water-retaining green net is laid on the surface of the solidified soil layer and anchored using fasteners. The breathable and water-retaining green net is a three-dimensional mesh structure made of polyethylene or polypropylene with a mesh size of 5mm to 10mm and a unit area mass of 200g / m² to 300g / m², providing good air permeability and water retention. The breathable and water-retaining green net is laid out on the surface of the solidified soil layer along the slope direction, ensuring that the green net is flat, tightly attached to the surface, and without wrinkles or gaps. The overlap width between adjacent green net strips is not less than 100mm. U-shaped nails are used as fasteners, with a length of 150mm to 200mm. A row of U-shaped nails is laid every 1m to 2m along the slope direction, with a spacing of 0.5m to 1.0m between each row of U-shaped nails. The U-shaped nails are driven vertically into the solidified soil layer to a depth of 100mm to 150mm, firmly anchoring the breathable and water-retaining green net to the surface of the solidified soil layer.

[0069] The slope was continuously sprayed with 3 mm / day for 14 days to promote seed germination and seedling growth, forming a vegetation layer. Spraying was carried out using a sprinkler system or manual spraying. The sprinkler system consisted of a water source, water pump, water pipes, and nozzles. The nozzles were atomizing nozzles with a spray angle of 60 to 80 degrees and a spray radius of 5 to 10 meters. One nozzle was placed every 10 to 15 meters along the slope. Spraying was carried out twice a day, from 6:00 to 8:00 in the morning and from 18:00 to 20:00 in the evening, for 30 to 60 minutes each time. The daily spray volume was controlled at 3 mm, which is equivalent to 3 liters of water per square meter of slope per day. Spraying was carried out for 14 days, with a total spray volume of 42 mm. During the maintenance period, the breathable and water-retaining green net effectively reduced water evaporation and kept the surface of the solidified soil layer moist, providing sufficient moisture for seed germination. At the same time, the green net could buffer the impact of raindrops and prevent seeds from being washed away by rainwater. After 14 days of cultivation, the seeds germinate and seedlings emerge one after another. The seedlings reach a height of 50mm to 100mm, a root depth of 30mm to 50mm, and a vegetation coverage of 30% to 50%, forming an initial vegetation layer. As the vegetation continues to grow, the roots gradually extend downward and form a root network in the solidified soil layer. The stems and leaves of the above-ground parts gradually cover the slope, and the vegetation coverage gradually increases to 80% to 90%, forming a stable vegetation layer.

[0070] After construction, a 180-day curing and monitoring period was conducted. On the 180th day of curing, an artificial simulated rainfall test was carried out to verify the protective effect and long-term stability of the overlay layer. The final acceptance process incorporated on-site observation and test data; the main procedures and results are as follows: 1. Simulated rainfall experiment design An artificial rainfall simulation system was deployed in the experimental area to simulate a rainstorm with a rainfall intensity of 105 mm / h, lasting for 2 hours. During the experiment, slope runoff and erosion were monitored, and any peeling or slippage on the slope was observed. Before and after the experiment, 3D laser scanning was used to acquire slope point clouds to generate digital elevation models. Using the pre-rainfall digital elevation model as a benchmark, the elevation deviation of each point after rainfall was calculated, and the percentage of point clouds with elevation deviations less than 20 mm was obtained.

[0071] 2. Soil and vegetation index testing At the end of the 180-day curing period, quantitative tests were conducted on soil and vegetation indicators: Soil surface strength: The surface strength of the soil was tested using a micro penetrator. One measuring point was taken per square meter, and the average value was taken as the representative value of the surface strength.

[0072] Soil saturated permeability coefficient: tested according to the variable head permeability test in the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019).

[0073] Vegetation coverage: obtained through digital image correlation technology, calculating the percentage of green vegetation area to the slope area.

[0074] Root volume: Using a cylinder with a diameter and height of 10cm, undisturbed soil samples were taken at different locations on the slope. After carefully washing away the soil, the root volume was determined using the drainage method.

[0075] It is worth mentioning that five embodiments are given here. Under the premise that the molar ratio of urea to calcium ions in the urea-calcium acetate cementing solution is 1:1, the amounts of urea and calcium acetate are adjusted respectively, and their mass ratio (slag: dried sword bean powder: urea: calcium acetate: water) is as follows: Example 1: 85000:480:90:237:24000 Example 2: 85000:480:180:474:24000 Example 3: 85000:480:360:948:24000 Example 4: 85000:480:720:1896:24000 Example 5 (Control Example): Basically the same as Example 1, except that instead of spraying urea-calcium acetate cementing solution, only an equal amount of water as urea-calcium acetate cementing solution was sprayed and grass seeds were sown.

[0076] Table 1 shows the surface strength, saturated permeability coefficient, and plant growth characteristics of the solidified soil layer, illustrating the effects of EICP treatment on the surface strength, saturated permeability coefficient, and vegetation growth characteristics of the solidified soil layer. As shown in Table 1, the surface strength of the solidified soil layer in all the EICP-treated examples (Examples 1 to 4) was significantly higher than that of the control example (Example 5) without cementitious liquid spraying. The surface strength increased from 237 kPa to 689 kPa, and the saturated permeability coefficient decreased by more than one order of magnitude, from 1.3 × 10⁻⁶ in Example 5. -6 cm / s decreased to 1.2 × 10⁻⁶ in Example 4. -7 cm / s. With increasing cementitious liquid dosage, soil strength and impermeability gradually increased, but excessive dosage (Example 4) resulted in an excessively high soil surface strength of 689 kPa, leading to overly dense soil that inhibited vegetation growth, with a vegetation cover of only 2.3% and a root volume of only 3.3 cm³. Example 2, under a urea to calcium acetate mass ratio of 180:474, achieved a soil strength of 348 kPa and an impermeability of 4.7 × 10⁻⁶ cm / s. -7 The optimal balance was achieved in terms of cm / s and vegetation ecological indicators (coverage of 99.4% and root volume of 203.8 cm³), realizing the best synergy between engineering performance and ecological benefits.

[0077] Table 2 presents the results of the artificial rainfall simulation test, demonstrating the erosion resistance performance of each embodiment in the artificial rainfall simulation test: Table 2 shows that the erosion amounts of all EICP-treated examples (0.30 m³ to 0.41 m³) were significantly lower than the 0.78 m³ of the control example, proving that the slope cover layer constructed by EICP solidification and vegetation synergy in this invention can effectively control soil erosion. The percentage of point clouds with a slope elevation deviation of less than 20 mm is a key indicator for measuring slope smoothness and erosion resistance. Example 2 achieved 91% in this indicator, significantly higher than the 63% of other examples and the control example, indicating that it maintained the most stable slope morphology and had the strongest erosion resistance under extreme rainfall conditions. Although the runoff of the control example was slightly lower at 7.1 t / h, due to the lack of a low-permeability barrier layer formed by EICP and the cementing effect of calcium carbonate, the erosion depth reached 9.1 mm, and the erosion amount reached 0.78 m³, resulting in the most severe soil erosion on the slope. The experimental data fully demonstrate that the capillary barrier slope cover layer with EICP and vegetation synergy and its construction method provided by this invention can effectively enhance soil strength and possess excellent erosion resistance and overall stability.

[0078] Specifically, to compare the technical performance of the traditional geometric pore-filling model and the temperature-slope adaptive control model under different environmental conditions, experimental data are presented below for comparison: Table 3 compares the performance of solidified soil layers under different spraying volume calculation models: Table 3 shows that, under the same construction conditions, the embodiment using the adaptive control model exhibits a significant advantage in soil solidification performance compared to the embodiment using the traditional geometric model. Under low-temperature conditions (comparison between Examples 6 and 7), the traditional geometric model, which does not consider the effect of temperature on enzyme activity, resulted in a calcium carbonate precipitation of only 8.2 g / kg soil at an actual spraying rate of 21.0 L / m², a soil solidification surface strength of only 186 kPa, and a saturated permeability coefficient of 2.3 × 10⁻⁶. -6 cm / s, failing to meet the requirement of less than 1×10 -6 The design requirement was met with a spatial uniformity deviation as high as 28.5%, and the material utilization rate was only 62.3%. However, the adaptive control model, through temperature correction, increased the spraying rate to 32.8 L / m², achieved a calcium carbonate precipitation of 12.6 g / kg soil, increased the surface strength of the solidified soil layer to 312 kPa, and reduced the saturated permeability coefficient to 6.8 × 10⁻⁶. -7 cm / s, spatial uniformity deviation reduced to 9.2%, and material utilization rate increased to 91.5%.

[0079] Under steep slope conditions (comparison between Examples 14 and 15), the traditional geometric model, which does not consider the effect of slope on the residence time of the cementitious liquid, resulted in a calcium carbonate precipitation of only 7.5 g / kg soil on a 45-degree slope, a decrease in the surface strength of the solidified soil layer to 172 kPa, and a saturated permeability coefficient as high as 3.1 × 10⁻⁶. -6 The spraying speed was [cm / s], the spatial uniformity deviation reached 34.2%, and the material utilization rate was only 54.8%. The adaptive control model, through slope correction, increased the spraying rate to 35.6 L / m², the calcium carbonate precipitation to 12.5 g / kg soil, increased the surface strength of the solidified soil layer to 315 kPa, and reduced the saturated permeability coefficient to 6.5 × 10⁻⁶. -7 cm / s, spatial uniformity deviation reduced to 10.1%, and material utilization rate increased to 90.3%.

[0080] Table 4 compares the long-term stability of slopes under different spraying volume calculation models: Table 4 shows that the adaptive control model also demonstrates significant advantages in long-term slope stability. After a 180-day curing period, the vegetation coverage of the examples using the adaptive control model reached over 95%, while the vegetation coverage of the examples using the traditional geometric model fluctuated between 65.8% and 88.2%. Regarding erosion resistance, the erosion amount of the examples using the adaptive control model was controlled between 0.24 m³ and 0.31 m³, while the erosion amount of the examples using the traditional geometric model was between 0.38 m³ and 0.72 m³, with a maximum difference of 2.9 times. In terms of crack density after wet-dry cycles, the crack density of the examples using the adaptive control model was controlled between 0.3 cracks / m² and 0.8 cracks / m², while the crack density of the examples using the traditional geometric model was between 1.7 cracks / m² and 4.5 cracks / m², with a maximum difference of 7.5 times. The overall stability score shows that the adaptive control model implementation score is between 92.8 and 97.3, while the traditional geometric model implementation score is between 58.9 and 82.1, with an average improvement of about 20%.

[0081] Experimental data demonstrate that the temperature-enzyme activity-slope retention-reaction conversion rate-spraying amount full-link closed-loop adaptive control system proposed in this invention can effectively solve the problem of unstable conversion efficiency of traditional geometric pore filling models under different temperature and slope conditions, ensure the uniformity of calcium carbonate precipitation in spatial distribution, significantly improve the mechanical properties, impermeability and long-term stability of the solidified soil layer, and achieve a significant increase in material utilization and a significant enhancement of slope protection effect.

[0082] In summary, the construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to the embodiments of this application is clarified. First, a coarse-particle guide layer composed of recycled aggregate from construction waste is constructed on the excavated and leveled slope surface, and geotextile is laid on its surface as a filter layer. Then, a mixing-type enzyme-induced calcium carbonate precipitation process is used, in which dried sword bean powder is used as a urease source and pre-mixed evenly with the slag soil. This mixture is then laid in layers, compacted, and sprayed with urea-calcium acetate cementitious liquid, causing calcium carbonate to precipitate evenly along the soil depth, forming a high-strength, low-permeability solidified soil layer, fundamentally solving the problems of traditional grouting. The uneven distribution of calcium carbonate caused by the method significantly improves the mechanical strength and resistance to degradation of the fine-grained soil layer. Finally, herbaceous and woody plant seeds are sown on the surface of the solidified soil layer and covered to form a vegetation layer. Through the biological reinforcement effect of the vegetation roots and the raindrop buffering effect of the above-ground parts, a structural seepage prevention-ecological protection composite system is constructed in synergy with the solidified soil layer. A significant change in permeability coefficient is formed between the low-permeability solidified layer and the underlying high-permeability drainage layer, creating an efficient capillary resistance effect. The synergistic effect of the three effectively solves the problems of stability, durability and seepage prevention of the cover layer in steep slope environments.

[0083] Furthermore, an enzyme-induced calcium carbonate precipitation and vegetation synergistic slope cover layer is also provided, which is constructed using the above-mentioned construction method for an enzyme-induced calcium carbonate precipitation and vegetation synergistic slope cover layer. Figure 5 This is a schematic diagram of the structure of a slope cover layer in which enzyme-induced calcium carbonate precipitation and vegetation work synergistically. (Example) Figure 5 As shown, the capillary-impeded slope cover layer of the present invention, which combines EICP and vegetation, comprises, from bottom to top: a slope 1, a coarse-particle drainage layer 2, a geotextile 3, a solidified soil layer 4, and a vegetation layer 5. The coarse-particle drainage layer 2 is composed of recycled construction waste aggregate with a particle size of 10mm to 50mm, a compaction degree of not less than 90%, a thickness of 100mm to 200mm, and a saturated permeability coefficient of 1×10⁻⁶. -2 Up to 1×10 -1 cm / s, used for lateral drainage of rainwater. Geotextile 3 is located between the coarse-grained drainage layer 2 and the solidified soil layer 4, serving as a filter and isolation layer. The solidified soil layer 4 is a slag soil layer mineralized using EICP technology, with a compaction degree of not less than 90% and a saturated permeability coefficient of less than 1×10. -6 The vegetation layer 5 consists of mixed seeds of Bahia grass, Bermuda grass, tall fescue, and pig manure bean, sown at a depth of 10 mm below the surface of the solidified soil layer 4. The total thickness is 200 mm to 600 mm.

[0084] The above-described embodiments are merely illustrative of several implementation methods of this disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the patent for the embodiments of this disclosure. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the embodiments of this disclosure, and these all fall within the protection scope of the embodiments of this disclosure. Therefore, the protection scope of the embodiments of this disclosure should be determined by the appended claims. As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and detail can be made without departing from the spirit and scope of the present invention as defined in the appended claims.

[0085] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for constructing a slope cover layer that synergistically induces calcium carbonate precipitation and vegetation growth, characterized in that, include: S1. The construction waste is crushed and screened to obtain recycled aggregate with a particle size of 10mm-50mm. The recycled aggregate is then laid and compacted in layers on the excavated and leveled slope surface to form a coarse particle guide layer. S2. Lay geotextile on the surface of the coarse particle drainage layer, with an overlap width of not less than 100mm between adjacent geotextiles and stitched together to form a reverse filter isolation layer; S3. The dried sword bean seeds are crushed and sieved to obtain dried sword bean powder. The dried sword bean powder and the sieved slag are dry-mixed in a mixing equipment to obtain mixed soil. At the same time, urea and calcium acetate are dissolved in water at a molar ratio of urea to calcium ions of 1:1 and then mixed to prepare a cementing solution. S4. The mixed soil is laid and compacted in layers on the filter isolation layer. After each layer is compacted, the cementing liquid is evenly sprayed onto the surface of the compacted soil using a pressure spraying device. The cementing liquid penetrates into the soil and undergoes urea hydrolysis and calcium carbonate precipitation under the catalysis of urease provided by the dried sword bean powder. The layer laying, compaction and spraying process is repeated until the design thickness is reached to form a solidified soil layer. S5. Before the final compaction of the solidified soil layer, herbaceous plant seeds and woody plant seeds are sown at a set sowing density at a depth of 10mm below the surface of the uncompacted soil. After the seeds are buried and fixed as the layer is compacted, a breathable and water-retaining green net is covered on the surface of the solidified soil layer and sprayed for maintenance to form a vegetation layer.

2. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, The compaction degree of the coarse particle guide layer shall not be less than 90%, and the thickness shall be 100mm-200mm.

3. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, The compaction degree of the solidified soil layer shall not be less than 90%, and the saturated permeability coefficient shall be less than 1×10. -6 cm / s, and the total thickness is 200mm-600mm.

4. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 2, characterized in that, Step S1 includes: S1.

1. Mechanically excavate the soil slope according to the designed slope ratio, remove boulders and debris with a diameter greater than 100mm from the slope surface, level and compact the excavated slope surface, and control the slope surface height difference within 20mm to obtain a level and qualified slope surface. S1.

2. The construction waste is fed into a crusher for crushing, and then screened by a multi-stage vibrating screen to cut particles with a diameter of 10mm-50mm to obtain recycled aggregate. The non-uniformity coefficient of the recycled aggregate is greater than 15 and the curvature coefficient is 1-3. S1.

3. The recycled aggregate is laid in layers on a leveled and qualified slope surface. Each layer has a loose thickness of 110mm. Each layer is compacted to a thickness of 100mm using a plate vibrator. The laying and compaction are repeated until the total design thickness is reached, resulting in a compaction degree of not less than 90% and a saturated permeability coefficient of 1×10⁻⁶. -2 -1×10 -1 A coarse-particle packing layer with a speed of cm / s.

5. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, Step S2 includes: S2.

1. Inspect and clean the surface of the coarse particle guide layer to eliminate sharp and protruding aggregate particles and obtain a pretreated base surface; S2.

2. Lay short-fiber needle-punched geotextile with a specification of 300g / m² on the pre-treated base surface along the slope direction, so that the geotextile is flat and tightly attached to the surface without wrinkles or gaps, and the overlap width of adjacent geotextiles is not less than 100mm. S2.

3. The overlapping parts of adjacent geotextile strips are fixed by sewing to form a reverse filter isolation layer.

6. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, Step S3 includes: S3.

1. The dried sword bean seeds are fed into a pulverizer for pulverization. The pulverized product is then sieved through a 1000-mesh sieve. The sieve-underfill material is collected to obtain dried sword bean powder. S3.

2. The slag soil that has passed through a 5mm sieve and the dry sword bean powder are put into the mixing equipment at a mass ratio of 85000:480 and thoroughly dry-mixed to make the dry sword bean powder evenly dispersed in the slag soil to obtain the mixed soil. S3.

3. Dissolve urea with a purity greater than 95% and calcium acetate with a purity greater than 95% separately in water and stir until completely dissolved, then mix them together. The molar ratio of urea to calcium ions is 1:

1. The mass ratio of slag, dried sword bean powder, urea, calcium acetate and water is 85000:480:(90-720):(237-1896):24000 to prepare a cementing solution.

7. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, Step S4 includes: S4.

1. Divide the mixed soil and cementitious liquid into equal parts according to the number of construction layers. Take one part of the mixed soil and spread it evenly on the filter isolation layer and level it. Use compaction machinery to compact it to a single layer thickness of 100mm and a compaction degree of not less than 90%, to obtain a physically compacted single layer. S4.

2. A pressure spraying device is used to evenly spray a portion of cementing liquid onto the surface of the physically compacted monolayer, allowing the cementing liquid to penetrate into the pores of the physically compacted monolayer and come into contact with the urease released by the dried sword bean powder. Under the catalysis of urease, urea undergoes a hydrolysis reaction to generate carbonate ions. The carbonate ions and calcium ions undergo a calcium carbonate precipitation reaction at the contact points of soil particles to form cement bridges, thus obtaining a mineralized monolayer. S4.

3. Using the mineralized monolayer as the base, repeat the paving, compaction, and spraying processes of steps S4.1 and S4.2, layering upwards until the total thickness reaches 200mm-600mm, and the saturated permeability coefficient is tested to be less than 1×10⁻⁶. -6 After reaching a speed of cm / s, a solidified soil layer is formed.

8. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, Step S5 includes: S5.

1. During the final layer construction of the solidified soil layer, a portion of mixed soil is laid on the mineralized underlying layer and kept uncompacted. Bahia grass seeds, Bermuda grass seeds, tall fescue seeds and pig manure seeds are evenly sown on the surface of the uncompacted soil at a sowing density of 10g / m² each to obtain a seed-containing preparatory layer. S5.

2. Compact the seed preparation layer to a single layer thickness of 100mm, so that the seeds are buried 10mm below the surface of the solidified soil layer as the soil is compressed. After compaction, spray the remaining cementing liquid evenly on the compacted surface for surface mineralization sealing treatment. S5.

3. Cover the surface of the solidified soil layer with a breathable and water-retaining green net and anchor it with fasteners. Spray the slope continuously for 14 days at a rate of 3 mm / day to promote seed germination and seedling growth and form a vegetation layer.

9. The construction method of the slope cover layer with enzyme-induced calcium carbonate precipitation and vegetation synergy according to claim 1, characterized in that, S4.2 includes: S4.2a. The surface temperature of the physically compacted monolayer is collected by an embedded thermocouple or an infrared thermometer to obtain the real-time slope temperature, and the enzyme activity correction coefficient is determined based on the real-time slope temperature. S4.2b. Based on the porosity and layer thickness of the physically compacted single layer, a slope retention time reduction coefficient is constructed in combination with the slope inclination angle. The enzyme activity correction coefficient and the slope retention time reduction coefficient are coupled as product factors and substituted into the first-order reaction kinetic model to obtain the effective conversion rate. Then, the original geometric pore filling spray volume is reverse compensated and corrected with the effective conversion rate to obtain the adaptive spray volume. S4.2c. Divide the physically compacted single layer into several construction zones along the slope direction. Calculate the adaptive spraying volume of each construction zone independently based on the local temperature and local slope of each construction zone. Use a pressure spraying device to spray the cementitious liquid in a zoned gradient according to the adaptive spraying volume corresponding to each construction zone.

10. A slope cover layer that synergistically induces calcium carbonate precipitation and vegetation, characterized in that, The enzyme-induced calcium carbonate precipitation and vegetation synergistic slope cover layer is constructed using the construction method for the enzyme-induced calcium carbonate precipitation and vegetation synergistic slope cover layer as described in any one of claims 1-9.

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