An ecological solidification method of enzyme-induced mineralization in combination with porous biomass carriers

Abstract

The application discloses an ecological solidification method combining enzyme-induced mineralization and porous biomass carriers, and belongs to the technical field of vegetation slope protection. The method comprises the following steps: S1, performing surface chemical etching and physical cracking treatment on a natural plant cellulose-based material to obtain a porous biomass carrier; S2, soaking and adsorbing a reaction precursor component solution on the porous biomass carrier to obtain a composite fiber material loaded with the reaction precursor component; S3, laying the composite fiber material on a matrix soil layer to be solidified; and S4, applying an active catalytic liquid containing biological urease and a delayed calcium source cementing liquid to the surface of the matrix soil layer. The porous biomass carrier is introduced into the matrix to be solidified, and combined with the enzyme-induced calcium carbonate precipitation (EICP) technology, and joint solidification treatment is performed by applying the enzyme liquid and the cementing liquid. The method not only further improves the overall ecological solidification effect of the matrix, but also improves the physical structure of the matrix by adding the porous biomass carrier, so that the matrix is more suitable for subsequent plant growth.

Description

Technical Field

[0001] This application relates to the field of vegetation slope protection technology, and in particular to an ecological solidification method combining enzyme-induced mineralization and porous biomass carrier. Background Technology

[0002] With the large-scale advancement of infrastructure construction in my country, projects such as road construction and mining inevitably disturb mountains and slopes, easily triggering geological problems such as soil erosion and landslides. In recent years, vegetation-based ecological slope protection, as a technology integrating engineering mechanics and botany, has shown good application potential. Vegetation roots can improve slope stability through mechanical anchoring, while also improving the ecological environment. However, in the early stages of vegetation growth, because the root system is not yet fully developed, its reinforcement effect on the slope soil is relatively weak, making it difficult to withstand the initial erosion from heavy rainfall.

[0003] To compensate for soil stabilization deficiencies during the early stages of plant growth, enzyme-induced calcium carbonate precipitation (EICP) technology has been introduced into slope reinforcement. EICP utilizes urease to catalyze the hydrolysis of urea, inducing calcium ions to form calcium carbonate precipitate, which binds loose soil particles together. Compared to traditional chemical reinforcement methods, EICP technology offers advantages such as less disturbance and relative environmental friendliness. However, existing EICP technologies still face some technical bottlenecks in practical engineering applications combined with ecological slope protection.

[0004] First, the EICP reaction rate is typically quite fast. In conventional processes, when cementing fluid is sprayed onto the soil surface, calcium carbonate precipitates tend to rapidly form and accumulate in large quantities on the surface. This rapid mineralization reaction easily leads to the rapid blockage of surface pores, forming a hard "surface crust" or hardened shell. This surface crust not only significantly hinders the further penetration and infiltration of subsequent cementing fluid into deeper soil layers, resulting in poor solidification of deeper soil and uneven mineralization distribution, but also, to some extent, limits the potential for improving the overall mechanical strength and shear resistance of the matrix soil layer.

[0005] Secondly, while existing technologies have attempted to combine EICP technology with conventional fiber materials (such as polypropylene or wool fibers) to improve soil toughness through fiber reinforcement, conventional fiber materials typically only provide physical reinforcement. Their internal structure is insufficient to serve as an effective carrier for reaction precursors, failing to effectively deliver substances involved in the EICP reaction to deep soil depths for in-situ targeted reactions. Furthermore, existing cementitious liquid systems generally lack effective mechanisms to control the reaction rate, thus failing to fundamentally alleviate the crusting and locking problem.

[0006] Therefore, how to collaboratively solve the surface crusting problem during the EICP curing process, effectively increase the penetration depth of the cementitious liquid, and enhance the overall mechanical properties of the ecological slope protection matrix are the problems that technicians in this field are currently committed to solving. Summary of the Invention

[0007] To address the aforementioned issues, this application aims to provide an ecological solidification method that combines enzyme-induced mineralization with porous biomass carriers, thereby reducing surface crusting during EICP solidification, increasing the penetration depth of the cementing solution, improving the ecological solidification effect, and making it suitable for plant growth.

[0008] To achieve the above objectives, the technical solution adopted in this application is as follows: An ecological solidification method combining enzyme-induced mineralization and porous biomass carriers includes: S1: Surface chemical etching and physical cracking treatment of natural plant cellulose-based materials are performed to obtain porous biomass carriers; S2: Soak the porous biomass carrier in a solution of adsorbent precursor components to obtain a composite fiber material loaded with the precursor components. S3: Lay the composite fiber material on the substrate soil layer to be cured; S4: Apply an active catalytic liquid containing biological urease and a delayed calcium source cementing liquid to the surface of the matrix soil layer. The delayed calcium source cementing liquid contains soluble calcium salts and polysaccharide macromolecular gelling agents.

[0009] Further, in step S1, the natural plant cellulose-based material is selected from one or more of wheat straw, corn straw, rice straw, reed straw, barley straw, sorghum straw, soybean straw, cotton straw, or hemp straw.

[0010] Further, step S1 includes: S101: Natural plant cellulose-based materials are cut into segments and mechanically extruded to cause some of the middle segments to crack. S102: Soak the cracked natural plant cellulose-based material in a NaOH solution with a mass concentration of 0.5%~1%; S103: The soaked natural plant cellulose-based material is dried until the moisture content is less than 15% to obtain a porous biomass carrier.

[0011] Further, step S2 includes: S201: Immerse the porous biomass carrier in a reaction precursor component solution, wherein the reaction precursor component solution is a urea solution with a concentration of 1.0~1.5 mol / L; S202: Soak at room temperature for 4-6 hours, stirring and grinding during the process; S203: Drain off excess solution to bring the porous biomass carrier to a saturated but non-dripping state, thus obtaining a composite fiber material loaded with reaction precursor components.

[0012] Further, in step S201, the mass-to-volume ratio of the porous biomass carrier to the reaction precursor component solution, expressed in kg / L, is 1:1.0 to 1:1.5.

[0013] Furthermore, in step S3, the composite fiber material is evenly laid on the substrate soil layer to be cured according to a 30% projected area ratio.

[0014] Further, in step S4, the active catalytic solution containing biological urease is prepared from soybean flour, and the preparation method includes: Mix soybean flour with water at a ratio of 120g / L; Centrifuge to remove the upper layer of grease and the lower layer of sediment.

[0015] Further, in step S4, the hysteretic calcium source cementing solution is prepared by mixing a cementing solution bulk and a sodium alginate solution; wherein, The cementing solution is mainly composed of urea and calcium acetate monohydrate in a 1:1 molar ratio to prepare a mixed solution with a concentration of 0.9 mol / L. The sodium alginate solution is an aqueous solution with a concentration of 2 g / L, and the mass ratio of the sodium alginate solution to the bulk cementitious solution is 1:1000.

[0016] This application also provides an eco-solidified matrix system constructed using the eco-solidification method described above.

[0017] Furthermore, the ecologically solidified matrix system comprises, from top to bottom: The solidified soil layer contains polysaccharide-calcium ion crosslinking compounds. The porous biomass carrier buried in the solidified soil layer has an enzyme-induced calcium carbonate microcrystalline network in its internal pores and physically cracked areas, and the calcium carbonate microcrystalline network co-anchors the porous biomass carrier and the matrix soil particles.

[0018] In summary, this application has the following beneficial effects: 1. This application provides an ecological solidification method combining enzyme-induced mineralization and porous biomass carriers. By subjecting natural plant cellulose-based materials to surface chemical etching and physical cracking treatment, it acquires excellent porous adsorption properties to load reaction precursor components. Combined with the application of a delayed-release calcium-based cementing solution containing polysaccharide macromolecular gelling agents, this method effectively alleviates the surface crusting and locking phenomenon caused by excessively rapid reactions in traditional EICP technology. The delayed-release cementing solution, encapsulated and slowed by the gel network, can penetrate deeper into the ground. Under the catalysis of reaction precursors released from the porous biomass carrier and urease, a calcium carbonate microcrystalline network is induced in situ on the inner and outer walls of the fibers and at microcracks. This method not only effectively improves the penetration depth and mineralization uniformity of the cementing solution but also significantly enhances the overall mechanical strength and shear resistance of the matrix soil layer through the synergistic effect of the physical reinforcement of the carrier and the chemical cementation of calcium carbonate.

[0019] 2. The method of this application utilizes a combination of specific EICP reactant concentrations and porous biomass carriers to effectively control the soil alkalization trend caused by mineralization reactions, maintain the pH and electrical conductivity of the surface soil within a suitable range for plant growth, and reduce the initial toxicity of alkaline byproducts to plant seeds. At the same time, the reaction precursors (such as urea solution) adsorbed in the porous biomass carrier can be converted into slow-release nitrogen fertilizer under the action of natural precipitation and microorganisms, providing a relatively stable nutrient supply for the entire growth cycle of subsequent slope protection vegetation (such as tall fescue), and alleviating the problem of plants turning yellow and lodging due to poor substrate.

[0020] 3. The ecological solidification matrix system constructed in this application forms a multi-dimensional synergistic protection mechanism at the macroscopic level, consisting of a "surface calcium carbonate hardened shell - middle layer modified biomass carrier reinforcement - deep plant root anchoring". Numerical simulation results show that under extreme conditions such as continuous heavy rainfall, the porous biomass carrier network can effectively improve the soil's permeability regulation capacity and reduce the local surge in pore water pressure. At the same time, the composite solidification structure significantly constrains the displacement and deformation of deep soil, maintaining the slope's safety factor at a relatively high level throughout the rainfall process, demonstrating superior disaster resistance and erosion prevention performance and engineering application potential. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of an ecological solidification method combining enzyme-induced mineralization and porous biomass carriers according to this application; Figure 2 This is an example diagram of a composite fiber material that may be used in an embodiment of this application; Figure 3This is a schematic diagram showing the loess slope model and the distribution of monitoring points (A, B, C) under different reinforcement methods in the embodiments of this application; Figure 4 This is a cloud map showing the pore water pressure distribution of loess slopes under different reinforcement methods 12 hours after rainfall, as described in the embodiments of this application. Figure 5 This is a graph showing the change of pore water pressure over time at various measuring points (measuring points A, B, and C) on a loess slope under different reinforcement methods in the embodiments of this application. Figure 6 This is a graph showing the change in volumetric moisture content of measuring point B under different reinforcement methods as a function of rainfall time in an embodiment of this application. Figure 7 This is a cloud map showing the displacement and deformation of loess slopes under different reinforcement methods 12 hours after rainfall, as described in the embodiments of this application. Figure 8 This is a graph showing the change in the safety factor of loess slopes with rainfall time under different reinforcement methods in the embodiments of this application. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions of this application will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Example 1 Reference Figure 1 This embodiment provides an ecological solidification method combining enzyme-induced mineralization and porous biomass carriers, comprising: S1: Surface chemical etching and physical cracking treatment of natural plant cellulose-based materials are performed to obtain porous biomass carriers; S2: Soak the porous biomass carrier in a solution of adsorbent precursor components to obtain a composite fiber material loaded with the precursor components. S3: Lay the composite fiber material on the substrate soil layer to be cured; S4: Apply an active catalytic liquid containing biological urease and a delayed calcium source cementing liquid to the surface of the matrix soil layer. The delayed calcium source cementing liquid contains soluble calcium salts and polysaccharide macromolecular gelling agents.

[0024] Specifically, taking wheat straw as an example of a natural plant cellulose-based material, a specific method is provided: (1) Configuring composite fiber materials: like Figure 2 As shown, wheat straw is cut into 3-5 cm segments and squeezed to crack some of the middle segments. To improve its adsorption capacity, the straw is soaked in a low concentration of 0.5%-1% NaOH solution for 2-4 hours, then washed (to prevent affecting vegetation growth), and dried until the original moisture content is less than 15%, thus obtaining a porous biomass carrier.

[0025] Prepare a urea solution with a concentration of 1.0-1.5 mol / L as the precursor component solution. Mix the porous biomass carrier with the urea solution at a weight:solution-to-volume ratio of 1:1.0 to 1:1.5, ensuring complete immersion. Soak at room temperature for 4-6 hours, gently stirring and grinding during this time to allow the urea solution to be fully adsorbed into the pores of the straw. Drain off excess solution, leaving the straw in a saturated but not dripping state, to obtain a composite fiber material loaded with the precursor component.

[0026] (2) Prepare an active catalytic solution containing biological urease: Purchased soybeans from the market were placed in a 40℃ oven and baked for 3 hours. Appropriate batches of dried soybeans were then placed into a grinder. After 30 seconds, the ground soybeans were removed and sieved through a 100-mesh sieve. The residue could be ground a second time. 120 g of soybean powder and 1 L of deionized water were selected. The soybean powder was poured into the deionized water and stirred with a magnetic stirrer for 15 minutes. The stirred soybean solution was then left to stand in a 4℃ freezer for 12 hours. The upper liquid mixture of the soybean solution was transferred to centrifuge tubes and centrifuged at 12000 r / min for 10 minutes. The upper layer of oil and the lower layer of solid precipitate were removed after centrifugation to obtain a crude urease solution, which was stored at 4℃ for later use.

[0027] (3) Prepare a lag-reducing calcium source cementing solution: Weigh 1 g of food-grade sodium alginate powder with a viscosity of 800-1200 mPa·s, dissolve it in 500 mL of deionized water, stir with a magnetic stir bar for 30 minutes until completely dissolved, and let it stand to remove bubbles for later use. Urea and calcium acetate monohydrate were mixed in a 1:1 molar ratio to prepare a solution with a concentration of 0.9 mol / L. 0.1% sodium alginate solution was then added to the cementing solution.

[0028] (4) Solidify the substrate soil layer: Clean the debris from the surface of the substrate soil layer of the slope to be solidified and level and compact it. Adjust the moisture content of the surface soil to about 15% to ensure the capillary penetration effect of the subsequent liquid.

[0029] The composite fiber material (wheat straw) loaded with reaction precursor components obtained in step (1) is evenly spread on the surface of the substrate soil layer, and its projected area coverage is controlled to be about 30%. In order to prevent weathering or erosion, light compaction or shallow rotary tillage (such as rotary tilling into the surface layer 1~3 cm) can be used to make it fully contact the substrate soil particles.

[0030] A low-pressure atomizing spraying device was used to spray the crude urease solution prepared in step (2) onto the surface of the soil layer where the composite fiber material was laid. The amount of urease solution sprayed at a time was controlled at 1.5 L / m², and two sprays were applied, with an interval of about 12 hours between each spray. During the resting period, the urease solution seeped down along the pores of the soil and formed a catalyst film on the surface of the wheat straw roughened by NaOH, providing in-situ targeting sites for subsequent deep crystallization.

[0031] After the urease infiltration is complete, the delayed calcium source cementing solution prepared in step (3) is sprayed onto the soil surface using a staggered spraying process. The amount of each spray is also controlled at 1.5 L / m², and two sprays are applied, with an interval of about 12 hours between each application. During the infiltration process, sodium alginate in the cementing solution forms a dynamic cross-linking network with calcium ions, which greatly reduces the initial reaction rate and avoids the instantaneous crusting and locking phenomenon on the surface. When the delayed cementing solution infiltrates to the composite fiber material, the high concentration of urea released from the straw cracks and the calcium ions released from depolymerization undergo explosive hydrolysis under the catalysis of urease, inducing a large number of aragonite-type calcium carbonate microcrystal networks to be generated in situ on the inner and outer walls of the straw and at the microcracks.

[0032] This ecological solidification method yields a specific ecological solidification matrix system, which, from top to bottom, comprises: The solidified soil layer contains polysaccharide-calcium ion crosslinking compounds. The porous biomass carrier buried in the solidified soil layer has an enzyme-induced calcium carbonate microcrystalline network in its internal pores and physically cracked areas, and the calcium carbonate microcrystalline network co-anchors the porous biomass carrier and the matrix soil particles.

[0033] Specifically, in this embodiment: The solidified soil layer refers to the loess slope soil that has undergone in-situ mineralization reaction after the coarse urease solution and the sluggish calcium source cementing liquid have permeated and interacted. The polysaccharide-calcium ion cross-linking complex contained inside refers to the gel network residue formed by the calcium ions dissociated from the 0.1% sodium alginate macromolecule added in step (3) and calcium acetate monohydrate during the infiltration process. The complex is distributed in trace amounts between the pores of loess particles, playing a role in water retention and improving the micro-ecology. The porous biomass carrier is the wheat straw fiber that has been cut into 3-5 cm segments, squeezed and cracked in the middle section, and etched away with 0.5%-1% NaOH solution to remove the surface hydrophobic wax layer in step (1). The internal pores and physical cracks contain an enzyme-induced network of calcium carbonate microcrystals. Specifically, this refers to the slow release of high-concentration urea loaded inside the wheat straw, which, along with externally infiltrated calcium acetate monohydrate, is catalyzed by crude soybean urease, resulting in a large number of spheroidal calcium carbonate crystal clusters induced in situ on the inner and outer walls of the straw fibers and at the compression cracks. The calcium carbonate microcrystalline network synergistically anchors the porous biomass carrier and the matrix soil particles. This refers to the above-mentioned spherulite-type calcium carbonate crystals, which grow in large numbers with the mechanical extrusion cracks in the middle section of wheat straw as the main nucleation sites. Like "micro-welding points", they tightly bond the wheat straw fibers and embed them into the surrounding loess particles, thus forming a three-dimensional root-soil composite stress structure that combines the tensile (reinforced) properties of wheat straw with the shear resistance properties of calcium carbonate.

[0034] Example 2 This embodiment provides the practical application of the ecological solidification method of Example 1 and the ecological solidification matrix system constructed using the ecological solidification method in vegetation slope protection engineering, and verifies its physical, chemical and mechanical effects through indoor simulation tests.

[0035] Specifically, after the slope has been stabilized for 6 days using the ecological stabilization method described in Example 1, vegetation is planted on the stabilized slope surface. Tall fescue, known for its adaptability and well-developed root system, is selected as the slope protection vegetation. Fescue seeds are evenly sown on the surface of the stabilized substrate soil, with a sowing density of 6000 seeds per square meter. After sowing, a thin layer of topsoil or non-woven fabric can be used to maintain initial habitat moisture, allowing for natural germination.

[0036] I. Practical Application Demonstration in Slope Engineering: 1. Sowing: Select tall fescue, which is highly adaptable and has a well-developed root system, as the slope protection vegetation. Evenly sow the tall fescue seeds on the surface of the solidified substrate soil, controlling the sowing density to 6000 seeds / square meter. After sowing, cover with a thin layer of topsoil or non-woven fabric to maintain initial habitat moisture, and wait for natural germination.

[0037] 2. Slow-release nutrients: The porous biomass carrier (wheat straw) buried in the shallow soil adsorbs a large amount of urea solution in the early stage. Under the action of natural rainfall and soil microorganisms, this urea is continuously and slowly released as nitrogen fertilizer, providing relatively stable nitrogen nutrition for the entire growth cycle of tall fescue, and improving the problems such as yellowing and lodging that may occur due to the poor loess soil.

[0038] 3. Anchoring effect: As tall fescue grows, its roots penetrate downwards through the surface EICP solidification layer and composite fiber network, reaching deep into the soil. The dense stems and leaves above ground effectively reduce rainwater erosion of the slope; the deep roots underground intertwine with the calcium carbonate microcrystals and soil particles generated by EICP mineralization, forming a three-dimensional "root-soil-calcium carbonate" force, which restrains the deformation of the deep soil through mechanical anchoring.

[0039] II. To quantitatively verify the microecological improvement and mechanical reinforcement effects of the above-mentioned ecological solidification system, the following indoor comparative and monitoring experiments were conducted: 1. Monitoring of soil physicochemical properties (pH and electrical conductivity) Method: Accurately weigh 30 g of loess sample solidified by the method in Example 1, put it into a volumetric flask, add 75 mL of deionized water, seal and shake vigorously for 3 minutes, then let stand for 30 minutes. Record the data using the pH pen and conductivity electrode of a multifunctional conductivity meter.

[0040] Results: Compared to conventional EICP technology, which causes a sharp increase in pH, the combined solidification system of this application effectively controls soil alkalization, maintaining the surface soil pH at approximately 8.32 and the electrical conductivity at approximately 146.21 μS / cm. The microenvironment effectively buffers the environmental impact of alkaline byproducts and does not cause toxicity to plant seeds.

[0041] 2. Method for testing the germination rate of grass seeds: Using the ecological solidification method of Example 1, an experimental substrate was constructed in a 13×13×10 cm transparent plastic pot. 100 tall fescue seeds were randomly selected and sown. An appropriate amount of deionized water was sprayed daily to maintain moisture. After 30 days of maintenance, the actual number of germinating tall fescue seeds was recorded.

[0042] Results: Thanks to the improved micro-ecological environment, the initial germination rate of tall fescue remained stable at over 75%.

[0043] 3. Root development and reinforcement depth simulation test method: Loess was filled into a PVC pipe with its inner wall coated with Vaseline and compacted. First, the surface soil inside the PVC pipe was treated with a combined ecological solidification method as described in Example 1. Then, tall fescue seeds (sowing density of 6000 seeds / m²) were weighed, evenly sown on the sample surface, and covered with 150 g / m² of soil and compacted. Daily maintenance was achieved by spraying with water of equal mass to the evaporation rate.

[0044] Results: One month later, the PVC pipe was cut open and the entire plant and soil column was taken out. Measurements showed that an EICP solidification layer with a thickness of about 20 cm had formed on the surface, and the tall fescue roots successfully penetrated the solidification layer, forming a root reinforcement zone with a depth of up to 100 cm.

[0045] 4. Surface strength test of cured layer: Method: Using a soil penetrator, the penetrator was kept perpendicular to the soil sample surface. The tip was inserted into the surface of the loess sample that had been cured in Example 1 at a speed of 1 cm / s. The surface strength data was read when the penetration depth reached 15 mm.

[0046] Results: Tests on loess samples reinforced for 6 days using the ecological solidification method of Example 1 showed that the surface penetration strength reached 428.34 kPa, which was 7.39 times higher than that of unreinforced loess samples.

[0047] III. To further verify the stability effect of the ecological solidification method and ecological solidification matrix system in slope protection engineering against extreme climate (such as heavy rainfall) in this embodiment, based on the soil parameters obtained from actual engineering and previous physical tests, a finite element numerical model of loess slope was constructed using COMSOL Multiphysics simulation software to conduct a refined comparative simulation analysis.

[0048] Physical parameter calibration: To obtain accurate simulation input parameters, this embodiment pre-constructed four sets of corresponding physical samples indoors to determine key parameters such as soil permeability coefficient, cohesion, and internal friction angle under various reinforcement methods. The four sets of samples were set as follows: E1: Control group (pure loess slope); Specifically, the loess moisture content was controlled at 20%, and after being mixed with water and stirred evenly, it was placed in a sealed bag and cured in a constant temperature curing chamber for 24 hours; on the first and second days, 3 L / m² of deionized water was sprayed on the sample surface, and then the soil column was wrapped with plastic wrap and placed in a constant temperature curing chamber for later use.

[0049] E2: Single Enzyme Soil Consolidation (EICP) Technology Reinforcement Group (or "EICP Group"); Specifically, based on the preparation of the E1 control group samples, the step of spraying deionized water was replaced with: spraying 1.5 L / m² of soybean urease solution with a concentration of 120 g / L, and spraying 1.5 L / m² of lag cementing solution with a concentration of 0.9 mol / L (using calcium acetate as the calcium source).

[0050] E3: Single vegetation reinforcement group (or "vegetation group"); Specifically, based on the E1 control group sample, an appropriate amount of tall fescue seeds (sowing density of 6000 seeds / m²) were weighed and evenly sprinkled on the sample surface, covered with 150 g / m² of soil and compacted. On the first and second days, 3 L / m² of deionized water was sprayed on the sample surface. After weighing and recording, the sample was placed indoors, and the same mass of clean water as the evaporation rate was sprayed daily, waiting for the plants to grow and mature.

[0051] E4: Reinforcement group (or “joint technology group”) of the ecological slope protection method of Example 1.

[0052] After obtaining the macroscopic physical and mechanical parameters of the four groups of samples, corresponding numerical analysis models were constructed in COMSOL Multiphysics software. Referring to an actual loess slope engineering project, a two-dimensional profile model was established, with a bottom width of 32.323 m, a height of 14.955 m, and a slope angle of approximately 30°. The parameters measured from the E1 to E4 groups of physical samples were assigned to the models, establishing four corresponding numerical comparison models (corresponding to the simulation results of E1 to E4 groups described later).

[0053] Specifically, such as Figure 3 As shown, regarding the boundary conditions and initial settings of the model: the top and surface of the slope are used as rainfall boundaries, the bottom of the slope is set as a fixed constraint boundary, and the left and right sides are set as roller support boundaries; the initial temperature field is set as a surface temperature of 40 ℃ and a ground temperature of 26 ℃, and is set as the steady-state result after the porous medium heat transfer calculation. Regarding the rainfall simulation settings: to simulate the slope instability process caused by extreme rainfall, the rainfall intensity is uniformly set to 20 mm / h. Simultaneously, three data acquisition points, A, B, and C, are set in the model, located at the top, middle, and bottom of the slope respectively, to dynamically monitor the evolution of key indicators such as pore water pressure and water content.

[0054] Analysis results as follows Figures 4 to 8 As shown: Figure 4 The image shows the pore water pressure distribution cloud map of loess slopes under different reinforcement methods 12 hours after rainfall, and the pore water pressure field of each reinforced slope changes significantly. Comparing the pore water pressure of slopes treated with different reinforcement methods, it was found that the control group had the smallest negative pressure area after rainfall, with a minimum negative pressure value of -45.4 kPa, indicating significant accumulation of pore water pressure in the unreinforced slope and a high risk to slope stability. The negative pressure area of ​​the slopes treated with EICP technology (E2) and vegetation reinforcement (E3) was significantly expanded, with minimum negative pressures reaching -52.3 kPa and -48.5 kPa, respectively. This indicates that EICP technology (E2) can effectively improve soil permeability and reduce pore water accumulation, while the vegetation root system reduces pore pressure through mechanical reinforcement and water infiltration regulation, thereby improving slope stability. The combined technology (E4) performed best, with the largest negative pressure area and a minimum pore pressure value of -55.4 kPa, which was 22.03% lower than the control group. This demonstrates the synergistic effect of multiple reinforcement measures, which can more effectively regulate the distribution of pore water pressure and significantly enhance the stability of loess slopes under rainfall conditions.

[0055] Figure 5 The curves showing the change of pore water pressure over time at different measuring points reveal that during the 12-hour rainfall event, the pore water pressure is significantly affected by the rainfall duration and fluctuates continuously over time. Compared to the control group (E1), the vegetation reinforcement (E3) showed a more significant water absorption effect from the vegetation roots, which led to a rapid reduction in moisture in the soil at the top of the slope, resulting in a greater decrease in pore water pressure. The EICP technology (E2) reduced soil permeability, allowing rainwater to flow away along the slope, resulting in the smoothest curve. The combined reinforcement (E4) combined the advantages of both methods, maintaining a low pore water pressure while also minimizing its variation range.

[0056] Figure 6The changes in volumetric moisture content of slope monitoring point B over 12 hours during rainfall were recorded in the control group, EICP technology, vegetation reinforcement, and combined reinforcement. The changes in moisture content at monitoring point B are shown. Due to its proximity to the waterline, the moisture content of each slope was around 26.53% at the beginning of rainfall. As the rainfall duration increased, the moisture content of each slope first decreased and then increased, but the initial decrease was relatively gradual, and the significant increase in moisture content began earlier. All three reinforcement methods effectively reduced the moisture content of the slope soil under the influence of rainfall. Vegetation reinforcement (E3) showed excellent results in the first 3 hours of rainfall; however, its effectiveness gradually declined as the rainfall duration lengthened. In contrast, EICP technology (E2) maintained good reinforcement effects even under prolonged rainfall conditions. Combined reinforcement technology (E4) combined the advantages of both methods, resulting in the most significant reinforcement effect.

[0057] Reference Figure 7 Comparing the displacement and deformation cloud maps of loess slopes under different reinforcement methods 12 hours after rainfall reveals significant differences in displacement distribution characteristics and reinforcement effects among the various slopes. Comparing the different reinforcement methods, the control group exhibits the largest displacement zone, with a maximum displacement of 10.1 mm, indicating that the unreinforced slope experiences significant soil strength degradation under rainfall, resulting in a high stability risk. The EICP technology (E2) reinforced slope shows a significant reduction in the high displacement zone, with a maximum displacement of 7.2 mm, demonstrating that EICP technology (E2) effectively inhibits rainfall-induced deformation by improving soil density and cementation. Vegetation reinforcement (E3) shows reduced displacement and deformation compared to the control group, but a certain high displacement zone still exists in the lower and middle parts of the slope, with a maximum displacement of 6.0 mm, a 40% reduction compared to the control group. The displacement was 59%, lower than that of slopes reinforced by EICP technology (E2), demonstrating that the surface reinforcement effect of vegetation roots has an inhibitory effect on shallow displacement. The combined reinforcement (E4) showed the smallest displacement deformation, with the high displacement zone basically disappearing. The overall color was bluish-green, and the maximum displacement was only 3.1 mm. Compared with the control group (E1), EICP technology (E2), and vegetation reinforcement (E3) slopes, the displacement was reduced by 69.31%, 56.94%, and 48.33%, respectively. This highlights the synergistic advantages of biological enzymes improving soil permeability and surface soil stabilization by vegetation roots, forming a combined reinforcement mechanism, which has the most significant inhibitory effect on rainfall-induced displacement.

[0058] Reference Figure 8 Taking the shallow two-dimensional profile of the slope as the analysis object, by averaging the local safety factors at various points in the shallow area, four curves showing the evolution of the average safety factor of the slope with rainfall duration were obtained, as shown below. Figure 8As shown in the analysis, the results show that in the initial stage of rainfall, the initial safety factor of the control group slope was the lowest, at only 1.23; the initial safety factors of the EICP technology (E2) and vegetation reinforcement (E3) slopes were the next lowest; while the safety factor of the combined reinforcement (E4) slope was the highest, reaching 1.37, which is 11.38% higher than that of the control group. As rainfall continued, the safety factors of all slopes showed a decreasing trend. The control group (E1) slope showed the most significant decrease, with its safety factor dropping to 1.02 after 12 hours of rainfall, a reduction of 17.07% from the initial value. The vegetation-reinforced (E3) slope followed, with a decrease of 15.79%. The safety factor of the EICP-reinforced (E2) slope showed a relatively gentle decreasing trend, with a decrease of only 12.60%. Although its initial safety factor was slightly lower than that of the vegetation-reinforced (E3) slope, it showed a trend of catching up with the vegetation-reinforced slope as the rainfall time extended. The combined reinforcement (E4) slope maintained the highest safety factor throughout the entire rainfall process and was least affected by rainfall. After 12 hours of rainfall, it still maintained a safety factor of 1.22, which was 19.61% higher than that of the control group, fully demonstrating its excellent slope protection performance.

[0059] In summary, the ecological solidification method combining enzyme-induced mineralization and porous biomass carriers provided in this application not only significantly improves the physicochemical properties of the slope matrix (such as pH regulation and slow-release nutrients) at the microscopic and plant physiological levels, ensuring the initial survival rate of vegetation establishment; but also, at the macroscopic mechanical level, forms a multi-dimensional synergistic protection mechanism through surface solidification, deep root-soil composite anchoring, and the permeability regulation effect of composite fibers. Under simulated extreme rainfall conditions, the combined solidification system of this application can more effectively control soil displacement and deformation, suppress the surge in pore water pressure, and maintain the slope safety factor at a relatively high level.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. An ecological solidification method combining enzyme-induced mineralization and porous biomass carriers, characterized in that, include: S1: Surface chemical etching and physical cracking treatment of natural plant cellulose-based materials are performed to obtain porous biomass carriers; S2: Soak the porous biomass carrier in a solution of adsorbent precursor components to obtain a composite fiber material loaded with the precursor components. S3: Lay the composite fiber material on the substrate soil layer to be cured; S4: Apply an active catalytic liquid containing biological urease and a delayed calcium source cementing liquid to the surface of the matrix soil layer. The delayed calcium source cementing liquid contains soluble calcium salts and polysaccharide macromolecular gelling agents.

2. The ecological solidification method according to claim 1, characterized in that, In step S1, the natural plant cellulose-based material is selected from one or more of wheat straw, corn straw, rice straw, reed straw, barley straw, sorghum straw, soybean straw, cotton straw, or hemp straw.

3. The ecological solidification method according to claim 1, characterized in that, Step S1 includes: S101: Natural plant cellulose-based materials are cut into segments and mechanically extruded to cause some of the middle segments to crack. S102: Soak the cracked natural plant cellulose-based material in a NaOH solution with a mass concentration of 0.5%~1%; S103: The soaked natural plant cellulose-based material is dried until the moisture content is less than 15% to obtain a porous biomass carrier.

4. The ecological solidification method according to claim 1, characterized in that, Step S2 includes: S201: Immerse the porous biomass carrier in a reaction precursor component solution, wherein the reaction precursor component solution is a urea solution with a concentration of 1.0~1.5 mol / L; S202: Soak at room temperature for 4-6 hours, stirring and grinding during the process; S203: Drain off excess solution to bring the porous biomass carrier to a saturated but non-dripping state, thus obtaining a composite fiber material loaded with reaction precursor components.

5. The ecological solidification method according to claim 4, characterized in that, In step S201, the mass-to-volume ratio of the porous biomass carrier to the reaction precursor component solution, expressed in kg / L, is 1:1.0 to 1:1.

5.

6. The ecological solidification method according to claim 1, characterized in that, In step S4, the active catalytic solution containing biological urease is prepared from soybean flour, and the preparation method includes: Mix soybean flour with water at a ratio of 120 g / L; Centrifuge to remove the upper layer of grease and the lower layer of sediment.

7. The ecological solidification method according to claim 1, characterized in that, In step S4, the hysteretic calcium source cementing solution is prepared by mixing a cementing solution bulk and a sodium alginate solution; wherein, The cementing solution is mainly composed of urea and calcium acetate monohydrate in a 1:1 molar ratio to prepare a mixed solution with a concentration of 0.9 mol / L. The sodium alginate solution is an aqueous solution with a concentration of 2 g / L, and the mass ratio of the sodium alginate solution to the bulk cementitious solution is 1:1000.

8. An eco-solidified matrix system constructed by the eco-solidification method according to any one of claims 1-7.

9. The ecological solidification matrix system according to claim 8, characterized in that, Top to bottom includes: The solidified soil layer contains polysaccharide-calcium ion crosslinking compounds. The porous biomass carrier buried in the solidified soil layer has an enzyme-induced calcium carbonate microcrystalline network in its internal pores and physically cracked areas, and the calcium carbonate microcrystalline network co-anchors the porous biomass carrier and the matrix soil particles.

10. The application of the ecological solidification matrix system as described in claim 8 in vegetation slope protection engineering.

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