Method for soil reinforcement by biomimetic mineralization based on multi-field coupling

Abstract

The application provides a kind of based on multi-field coupling's bionic mineralization reinforced soil method, belongs to geotechnical engineering technical field.The bionic mineralization reinforced soil method includes: first, the soil quality of target area is detected, obtains soil structure type, calculates soil structure correction coefficient, gas correction coefficient and calcium ion correction coefficient;Then, vacuum preloading system and ultrasonic excitation system are arranged in target area at intervals, based on soil structure type and soil structure correction coefficient, the working parameters of vacuum preloading system and ultrasonic excitation system are set, vacuum preloading system and ultrasonic excitation system are opened in turn, and reinforcing solution containing calcium source and bionic crystal form control agent is injected into target area;Finally, stop injecting reinforcing solution, ammonia and carbon dioxide are injected in turn, carbon dioxide is converted into carbonate ion under ammonia atmosphere and bionic mineralization reaction occurs with reinforcing solution, so as to reinforce target area.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology, specifically relating to a biomimetic mineralization method for soil reinforcement based on multi-field coupling. Background Technology

[0002] Vacuum preloading technology is an economical and efficient method for treating weak foundations. By laying a sealing membrane and applying negative pressure, pore water is forced to drain from the drainage board, thereby achieving soil consolidation and strength improvement. It has been widely used in engineering practice.

[0003] However, the relevant technologies have several problems in the vacuum preloading process. In the early stages of vacuum preloading, the weak foundation's bearing capacity is insufficient, making it difficult for construction personnel and heavy machinery to enter the site, and a long drying period is usually required. In the middle stages of vacuum preloading, the initial porosity of the foundation is relatively high, leading to large deformations and settlements in the soil, which can easily cause the plastic drainage pipes to twist and deform, reducing drainage efficiency. In the later stages of vacuum preloading, due to the combined effects of filter membrane clogging, particle migration, and non-uniform consolidation, soil drainage is hindered, permeability decreases, and the efficiency of vacuum pressure transmission declines, further hindering drainage consolidation and creating a vicious cycle. While traditional physical flushing or chemical dispersion methods can temporarily alleviate these problems, they have drawbacks such as high costs and the potential for leaving harmful substances.

[0004] To address the aforementioned issues, there is an urgent need to develop a novel soft soil foundation treatment technology that can effectively prevent drainage channel blockage during vacuum preloading while balancing drainage efficiency and foundation reinforcement. Summary of the Invention

[0005] In view of this, in order to solve at least one technical problem in related technologies and other aspects, the present invention proposes a biomimetic soil mineralization reinforcement method based on multi-field coupling, comprising the following steps.

[0006] Step (1): Test the soil in the target area, determine the soil structure type based on the test results, and calculate the soil structure correction coefficient, gas correction coefficient and calcium ion correction coefficient.

[0007] Step (2): Vacuum preloading system and ultrasonic excitation system are set up at intervals in the target area. The working parameters of vacuum preloading system and ultrasonic excitation system are set according to soil structure type and soil structure correction coefficient. Vacuum preloading system and ultrasonic excitation system are turned on in sequence. A reinforcement solution containing calcium source and biomimetic crystal form regulator is injected into the target area so that the reinforcement solution is uniformly diffused under the action of water-based ultrasonic field formed in the target area.

[0008] Step (3): Stop injecting the reinforcement solution. According to the amount of reinforcement solution and the gas correction coefficient and calcium ion correction coefficient, inject ammonia and carbon dioxide into the water-based ultrasonic field in sequence. Carbon dioxide is converted into carbonate ions in the ammonia atmosphere and undergoes a biomimetic mineralization reaction with the reinforcement solution to generate calcium carbonate, thereby reinforcing the target area.

[0009] According to an embodiment of the present invention, the test results include the first characteristic value of the foundation bearing capacity and the first deformation modulus of the target area before reinforcement, as well as the fine particle content, median particle size and effective particle size of the sand particles in the target area, wherein the fine particle content is the mass fraction of sand particles with a particle size less than 0.075 mm, and the effective particle size is the particle size when the cumulative particle size distribution number of sand particles reaches 10% of the mass.

[0010] Soil structure types include fine-grained, transitional, and skeleton types. Among them, the fine-grained type has a fine particle content of more than 50% and a median particle size of less than 0.02 mm; the transitional type has a fine particle content of 20% to 50% and a median particle size of 0.02 mm to 0.075 mm; and the skeleton type has a fine particle content of less than 20% and a median particle size of more than 0.75 mm.

[0011] According to an embodiment of the present invention, the method for calculating the soil structure correction coefficient includes: calculating the soil structure correction coefficient by weighting the median particle size, effective particle size, and fine particle content based on the soil structure type.

[0012] According to an embodiment of the present invention, the ultrasonic excitation system is a two-stage operating mode comprising a seepage induction stage and a deposition orientation stage, with a smooth transition between the two stages via a linear ramp function; wherein, the seepage induction stage employs a continuous ultrasonic mode, and the deposition orientation stage employs a pulsed ultrasonic mode.

[0013] According to an embodiment of the present invention, the operating parameters of the ultrasonic excitation system include a target amplitude and a target power; the target amplitude is obtained by nonlinearly correcting the reference power of the ultrasonic excitation component with a soil structure correction factor; the target power is obtained by linearly correcting the reference amplitude of the ultrasonic excitation component with a soil structure correction factor.

[0014] According to an embodiment of the present invention, the target pressure applied by the vacuum preloading system follows a dynamic negative pressure traction path, which includes a first negative pressure stage and a second negative pressure stage corresponding to the seepage induction stage and the deposition orientation stage; the operating parameters of the vacuum preloading system include a first target pressure and a second target pressure; wherein, in the first negative pressure stage, the vacuum degree of the vacuum preloading system increases linearly from its initial value to the first target pressure over time; in the second negative pressure stage, the vacuum degree of the vacuum preloading system increases exponentially from the first target pressure over time and gradually approaches the second target pressure; when the vacuum degree reaches the first target pressure, the system switches from the first negative pressure stage to the second negative pressure stage.

[0015] According to an embodiment of the present invention, the first target pressure and the second target pressure are obtained by correcting the reference vacuum degree of the vacuum preloading system with a soil structure correction factor; wherein the first target pressure is less than the second target pressure.

[0016] According to an embodiment of the present invention, the target introduction flow rate of carbon dioxide is obtained based on the soil structure correction coefficient and the calcium source content in the reinforcement solution; the target introduction flow rate of ammonia is twice the target introduction flow rate of carbon dioxide.

[0017] According to embodiments of the present invention, the biomimetic mineralization method for soil reinforcement further includes:

[0018] Step (4): Detect the characteristic value of the bearing capacity of the second foundation and the second deformation modulus after reinforcement; under the condition that the characteristic value of the bearing capacity of the second foundation is not less than 1.5 times the characteristic value of the bearing capacity of the first foundation, and / or the second deformation modulus is not less than 2 times the first deformation modulus, complete the biomimetic mineralization reinforcement method for soil.

[0019] According to an embodiment of the present invention, step (4) further includes: performing a crystal distribution test on calcium carbonate; if it is found that the calcium carbonate crystals have agglomerated, the crystals are broken up by adjusting the conditions of the ultrasonic excitation system to prevent blockage.

[0020] According to embodiments of the present invention, by detecting the soil quality of the target area and determining the soil structure type and corresponding correction coefficients, differentiated treatment parameters can be formulated for different soil conditions, ensuring that subsequent processes match the actual conditions of the target area. By intermittently deploying a vacuum preloading system and an ultrasonic excitation system within the target area, and setting operating parameters based on the soil structure type and correction coefficients, the synergistic effect of vacuum negative pressure and ultrasonic oscillation can be achieved. After sequentially activating the two systems, a reinforcing solution is injected. Under the action of a water-based ultrasonic field, the solution diffuses uniformly in the soil, helping to avoid problems such as excessively high local concentrations or uneven diffusion. After stopping the injection, ammonia and carbon dioxide are injected sequentially according to the amount of reinforcing solution used and relevant correction coefficients. The carbon dioxide is converted into carbonate ions in the ammonia atmosphere and undergoes a biomimetic mineralization reaction with the reinforcing solution to generate calcium carbonate. This process, through the orderly introduction of gaseous reactants and combined with the previously determined parameters, can create a mineralization reinforcement effect in the soil. Overall, the present invention achieves controllable reinforcement for different soil conditions through detection and classification, parameter adaptation, multi-field synergy, and orderly injection of biomimetic mineralization reactants. Attached Figure Description

[0021] Figure 1 This is a flowchart of the biomimetic soil mineralization reinforcement method based on multi-field coupling in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the ultrasonic excitation component in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the layout of the biomimetic mineralization and soil reinforcement method based on multi-field coupling of the present invention.

[0024] [Explanation of Labels in the Attached Image]

[0025] In the accompanying drawings of this invention, the reference numerals have the following meanings:

[0026] 1-Ultrasonic generator; 2-Gas-liquid inlet; 3-Slow-release transition layer; 4-Ultrasonic vibrator; 5-Gas-liquid outlet; 6-Functional housing; 7-Annular fluid cavity; 8-Target area;

[0027] 11-Gas delivery unit; 12-Liquid delivery unit; 13-Pump; 14-Dike; 15-Sealing trench; 16-Vacuum pump; 17-Sealing membrane; 18-Vacuum filter tube; 19-Sand pad; 20-Drainage board; 21-Ultrasonic excitation component. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0031] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0032] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Where the terms "first," "second," etc., are used throughout the text, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data in the descriptions of "first," "second," etc., can be interchanged where appropriate.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] In the description of this invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, dimensions, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference symbols placed within parentheses in this invention should not be construed as limiting the scope of the invention.

[0036] Similarly, to simplify the invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0038] During the development of this invention, it was discovered that while vacuum preloading technology offers advantages in terms of efficiency and economy for soft soil foundation treatment, its engineering effectiveness is largely limited by the problem of drainage channel blockage. The migration and uncontrolled deposition of fine particles under negative pressure easily lead to concentrated blockage at the filter membrane and pore throat, causing a sharp decline in drainage efficiency. Traditional physical flushing or chemical dispersion methods can only provide temporary relief and have limitations such as the potential introduction of harmful substances. Meanwhile, although biomimetic mineralization technology can form a stable cemented structure between particles by regulating the nucleation and crystal form of calcium carbonate, possessing the potential to suppress fine particle migration, there is still a lack of effective control methods to achieve efficient carbon source diffusion, controllable deposition of mineralization products, and avoid pore throat blockage under negative pressure drainage conditions.

[0039] Further analysis revealed that water-based ultrasonic excitation can enhance mass transfer processes in the liquid phase and refine the size of mineralized products. If combined with a biomimetic mineralization system and applied to the area near the vacuum pre-compression drainage channel, it is expected to achieve synergistic regulation of mineralization deposition behavior while maintaining drainage capacity. Based on the above understanding, this invention proposes a technical solution that synergistically combines vacuum pre-compression, ultrasonic excitation, and biomimetic mineralization.

[0040] In this invention, the term "vacuum preloading technology" means: in the treatment of weak foundations, negative pressure is applied to the foundation by laying sealing membranes, vacuum pumps, and other equipment to form stable negative pressure boundary conditions. The vacuum degree is transmitted downward from the soil surface, causing pore water to be rapidly discharged from the vertical drainage board. Under the condition that the total stress remains constant, the decrease in pore water pressure leads to an increase in the effective stress of the soil, thereby inducing compression deformation of the soil skeleton, achieving drainage consolidation and strength improvement. In this invention, in addition to performing the conventional drainage consolidation function, the negative pressure gradient generated by the vacuum preloading system is also used to guide the directional migration of mineralization reaction media in the soil pores.

[0041] In this invention, the term "ultrasonic excitation technology" specifically refers to "biomimetic mineralization-induced calcium carbonate precipitation (BCICP)," which means that a high-frequency electrical signal is converted into mechanical vibration by an ultrasonic generator, and a water-based ultrasonic field is radiated into saturated soil through an ultrasonic excitation component. When ultrasound propagates in the liquid phase, it produces cavitation effects, microscale vibration disturbances, and localized mass transfer enhancement effects. In this invention, the effects of ultrasonic excitation include: breaking the static boundary layer in pore water to reduce seepage resistance and promoting uniform diffusion of the reaction medium in micropores; increasing the nucleation rate and inhibiting disordered crystal growth, resulting in finer and more uniformly distributed mineralization products; and enhancing the gas-liquid-solid multiphase interface contact, promoting the uniform spatial distribution of carbonate ions.

[0042] In this invention, the term "biomimetic mineralization technology" refers to the use of crystal form regulators, such as inorganic substances (e.g., boric acid), single-molecule organic substances (e.g., aspartic acid), or polymers (e.g., polyacrylic acid, chitosan), to directly regulate the nucleation, growth, and deposition behavior of calcium carbonate, replacing the role of microorganisms or enzymes. This technology is unaffected by environmental factors and can form a stable mineralized cement structure between particles through small pores. In this invention, the biomimetic mineralization reaction, by introducing the aforementioned crystal form regulators into the calcium source solution and coordinating the stepwise injection of ammonia and carbon dioxide, results in the formation of fine-grained, dispersed calcium carbonate that preferentially deposits on the surface and contact areas of soil particles.

[0043] Figure 1 This is a flowchart of a biomimetic soil mineralization reinforcement method based on multi-field coupling in an embodiment of the present invention.

[0044] This invention proposes a biomimetic method for soil mineralization reinforcement based on multi-field coupling, such as... Figure 1 As shown, it includes the following steps.

[0045] Step (1): Test the soil in the target area, determine the soil structure type based on the test results, and calculate the soil structure correction coefficient, gas correction coefficient and calcium ion correction coefficient.

[0046] Step (2): Vacuum preloading system and ultrasonic excitation system are set up at intervals in the target area. The working parameters of vacuum preloading system and ultrasonic excitation system are set according to soil structure type and soil structure correction coefficient. Vacuum preloading system and ultrasonic excitation system are turned on in sequence. A reinforcement solution containing calcium source and biomimetic crystal form regulator is injected into the target area so that the reinforcement solution is uniformly diffused under the action of water-based ultrasonic field formed in the target area.

[0047] Step (3): Stop injecting the reinforcement solution. According to the amount of reinforcement solution and the gas correction coefficient and calcium ion correction coefficient, inject ammonia and carbon dioxide into the water-based ultrasonic field in sequence. Carbon dioxide is converted into carbonate ions in the ammonia atmosphere and undergoes a biomimetic mineralization reaction with the reinforcement solution to generate calcium carbonate, thereby reinforcing the target area.

[0048] According to embodiments of the present invention, by detecting the soil quality of the target area and determining the soil structure type and corresponding correction coefficients, differentiated treatment parameters can be formulated for different soil conditions, ensuring that subsequent processes match the actual conditions of the target area. By intermittently deploying a vacuum preloading system and an ultrasonic excitation system within the target area, and setting operating parameters based on the soil structure type and correction coefficients, the synergistic effect of vacuum negative pressure and ultrasonic oscillation can be achieved. After sequentially activating the two systems, a reinforcing solution is injected. Under the action of a water-based ultrasonic field, the solution diffuses uniformly in the soil, helping to avoid problems such as excessively high local concentrations or uneven diffusion. After stopping the injection, ammonia and carbon dioxide are injected sequentially according to the amount of reinforcing solution used and relevant correction coefficients. The carbon dioxide is converted into carbonate ions in the ammonia atmosphere and undergoes a biomimetic mineralization reaction with the reinforcing solution to generate calcium carbonate. This process, through the orderly introduction of gaseous reactants and combined with the previously determined parameters, can create a mineralization reinforcement effect in the soil. Overall, the present invention achieves controllable reinforcement for different soil conditions through detection and classification, parameter adaptation, multi-field synergy, and orderly injection of biomimetic mineralization reactants.

[0049] In some specific embodiments, the reinforcement mechanism of this invention lies in introducing an ultrasonic excitation field and a biomimetic mineralization control system into a water-based environment to synergistically regulate the nucleation, growth, and deposition behavior of calcium carbonate, actively controlling its crystal form, morphology, and scale distribution. This results in the generated calcium carbonate exhibiting fine-grained, dispersed, and more interfacially active characteristics, thereby enhancing the cementation and bridging effect between calcium carbonate and soil particles. Specifically, through the cavitation effect and microscale disturbance of ultrasonic excitation in pore water, the diffusion and transport of gaseous or dissolved carbon sources in soil pores are significantly promoted, improving the problems of uneven reactant distribution and local precipitation accumulation in traditional mineralization processes. Simultaneously, combined with the induced deposition of calcium carbonate, dual regulation of the microscopic morphology and macroscopic distribution of calcium carbonate is achieved, allowing fine-grained soil particles to be stably cemented to the surface of larger particles or the framework, improving the structural stability and overall mechanical properties of the soil while maintaining pore connectivity.

[0050] Figure 3 This is a schematic diagram of the layout of the biomimetic mineralization and soil reinforcement method based on multi-field coupling of the present invention.

[0051] In some specific embodiments, such as Figure 3 As shown, the vacuum preloading system consists of three parts: a drainage unit, a pressurization unit, and a sealing unit. The drainage unit's function is to alter the foundation drainage boundary, accelerate the discharge of pore water via a vacuum pump 16, and transmit vacuum pressure. Specifically, the drainage unit consists of drainage boards 20 serving as vertical drainage channels, with a sand cushion layer 19 acting as a horizontal drainage layer. The pressurization unit's function is to form and transmit a vacuum load, expelling air and water from the soil within the target area 8. Specifically, the pressurization unit consists of a main pipe and a filter pipe. More specifically, the main pipe transmits the vacuum, while the filter pipe (with an opening rate > 5%) absorbs water. The sealing unit's function is to maintain the stability of the vacuum load and prevent air leakage. The sealing unit includes a surface seal consisting of a sealing membrane 17, a sealing trench 15, and surface crack treatment, as well as a deep seal constructed using methods such as deep mud mixing, sheet piles, high-pressure jet grouting, and grouting.

[0052] In some specific embodiments, such as Figures 2-3 As shown, the ultrasonic excitation system includes a pumping unit, a liquid storage unit, an ultrasonic generator 1, and an ultrasonic excitation component 21. The ultrasonic generator 1, acting as the ultrasonic excitation source, is connected to the ultrasonic excitation component 21 to generate a controllable water-based sound field in saturated soil. The ultrasonic excitation component 21 is positioned near the drainage plate 20 of the vacuum preloading system. It is used to synergistically introduce a sound field and reinforce the liquid and gaseous reaction media (including ammonia and carbon dioxide) under vacuum negative pressure, thereby directionally controlling the mass transfer and mineralization deposition processes in the area surrounding the drainage channel. The ultrasonic excitation component 21 is a composite functional component positioned near the drainage plate 20, used to synergistically apply a sound field and reinforce the liquid and gaseous reaction media under vacuum negative pressure. It is axially extending columnar in shape, arranged along the soil depth direction, and is substantially parallel to the drainage plate 20.

[0053] Figure 2 This is a schematic diagram of the structure of the ultrasonic excitation component in an embodiment of the present invention.

[0054] In some more specific embodiments, such as Figure 2As shown, the ultrasonic excitation component 21 mainly includes: an ultrasonic vibrator 4, a functional housing 6, a liquid-gas composite channel system, and a sealed buffer structure. The ultrasonic vibrator 4 is located at the axial center of the ultrasonic excitation component 21, with one end electrically connected to the ultrasonic generator 1 via a sealed connection structure. It converts the high-frequency electrical signal output from the external ultrasonic generator 1 into mechanical vibration and radiates a water-based ultrasonic field to the surrounding saturated soil. Specifically, the ultrasonic vibrator 4 preferably operates at a frequency of 20-56 kHz and has an output power of 600-2200 W, generating stable cavitation effects, microscale vibration disturbances, and localized mass transfer enhancement effects in saturated pore water. The outer surface of the ultrasonic vibrator 4 maintains acoustic coupling with the functional housing 6, allowing acoustic energy to be effectively transmitted to the soil area surrounding the drainage board 20 through the housing. The functional housing 6 is a hollow cylindrical structure covering the outside of the ultrasonic vibrator 4. Its material is a corrosion-resistant, pressure-resistant metal or composite material with good sound conductivity, preferably stainless steel or a high-strength alloy. The functional housing 6 has multiple spaced liquid-gas outlets along its axial direction, which radially penetrate the wall of the functional housing 6 to facilitate the directional release of liquid and gaseous media from the interior of the component into the surrounding soil. The diameter, number, and axial spacing of the through holes can be adjusted according to the soil permeability, mineralization range, and the depth of the drainage board 20 to form a mineralization control zone with graded action along the depth direction. The outer surface of the functional housing 6 is in direct contact with the soil. The liquid-gas composite channel is located inside the functional housing 6 and outside the ultrasonic vibrator 4, with an annular fluid cavity 7 arranged axially. It is connected to the pumping unit (including the liquid delivery unit 12 and the gas delivery unit 11) for connecting to the liquid delivery unit 12 through the gas-liquid inlet 2 to inject a reinforcing solution into the soil around the drainage board 20, or for connecting to the gas delivery unit 11 to input ammonia and carbon dioxide for introducing gaseous reaction media into the soil in stages. The pumping process is achieved by pump 13. A slow-release transition layer 3 is provided between the liquid-gas composite channel and the functional shell 6. The slow-release transition layer 3 is a porous medium layer with a certain thickness, and its pore size is smaller than the through-hole diameter of the functional shell 6. This structure uses pore resistance to equalize the pressure, dissipate energy, and modulate the diffusion of the liquid and gas phase reaction media, allowing the reaction media to pass through the porous functional shell 6 and the gas-liquid outlet 5 in a multi-point, low-speed, and non-directional manner and enter the pores of the surrounding soil. The sealing buffer structure is used to prevent media backflow, gas-liquid crosstalk, and particle back intrusion under the combined action of grouting, vacuum negative pressure, and ultrasonic vibration. The sealing buffer structure can adopt a passive one-way valve structure, and the preferred material is stainless steel.

[0055] In some specific embodiments, the calcium source in the reinforcement solution is preferably a calcium chloride solution, and the biomimetic crystal form regulator includes, but is not limited to, amino acids, polymers, or boric acid.

[0056] In some more specific embodiments, the reinforcement solution can be designed as an amino acid-regulated type, a polyacrylic acid (PAA)-regulated type, or a boric acid-regulated type. The design of the reinforcement solution varies depending on the reinforcement scheme and the specific conditions of the foundation, selecting the concentration of calcium chloride, the added regulator, and the concentration of the regulator. Specifically, the amino acid-regulated reinforcement solution can consist of 0.5-2 mol / L CaCl2 solution and 0.5-2 mol / L amino acid solution, wherein the amino acid composition is at least one selected from glutamic acid, tryptophan, arginine, and aspartic acid, and the pH of the added solution is 10; the polyacrylic acid-regulated reinforcement solution can consist of 0.5-2 mol / L CaCl2 solution and 1-6 g / L polyacrylic acid; the boric acid-regulated reinforcement solution can consist of 0.5-2 mol / L CaCl2 solution and 0.05-0.8 g / L H3BO3.

[0057] In some more specific embodiments, the solution is prepared using a direct preparation method, and tap water is sufficient. The dried solute is added to a beaker and shaken well. The solution is stirred until no precipitate remains at the bottom and then stored in a constant temperature and humidity chamber at 20°C. The dosage of the solution is based on 1% of the mass of the soil to produce calcium carbonate, and the dosage can be adjusted flexibly according to actual needs.

[0058] In some specific embodiments, after the vacuum preloading system is completed and the drainage board 20 is installed, the ultrasonic excitation component 21 is installed first. The ultrasonic excitation component 21 is arranged in a staggered parallel manner along the drainage board 20, and its horizontal distance from the center line of the drainage board 20 is controlled within the range of 50-75mm.

[0059] According to an embodiment of the present invention, the detection results include the first characteristic value of the foundation bearing capacity of the target area before reinforcement (f ak,before ) and the first deformation modulus (E s,before ), and the fine particle content (FC) and median particle size (D) of sand particles in the target area. 50 ) and effective particle size (D 10 The fine particle content is the mass fraction of sand particles with a diameter less than 0.075 mm, and the effective particle size is the particle size at which the cumulative particle size distribution number of sand particles reaches 10% of the mass. Soil structure types include fine-grained, transitional, and skeletal types. The fine-grained type has a fine particle content greater than 50% and a median particle size less than 0.02 mm; the transitional type has a fine particle content of 20%-50% and a median particle size of 0.02 mm-0.075 mm; and the skeletal type has a fine particle content less than 20% and a median particle size greater than 0.75 mm.

[0060] According to embodiments of the present invention, by detecting the first characteristic value of the foundation bearing capacity and the first deformation modulus of the target area before reinforcement, as well as the fine particle content, median particle size, and effective particle size of the sand particles, multiple quantitative indicators reflecting the soil condition can be obtained. Based on this, the soil structure is clearly divided into three categories—fine-grained, transitional, and skeletal—accurately classifying the soil characteristics of the target area according to the fine particle content and median particle size. This classification method allows the setting of subsequent process parameters to match the key engineering properties of different soil types, such as permeability and particle migration characteristics, avoiding the potential for insufficient adaptability caused by a single parameter processing method.

[0061] In some specific embodiments, the fine particle content (FC) is calculated as shown in equation (1).

[0062] .

[0063] Where m (d < 0.075 mm) is the content of particles with a diameter less than 0.075 mm. total It refers to the mass of all soil samples.

[0064] According to D 50 Based on the combined characteristics with FC, the soil structure type of the target area is divided into three granular structure zones. Among them, the engineering meaning of fine-grained type is that the target area has high sound attenuation and is prone to clogging; the engineering meaning of transitional type is that the target area has good controllable migration conditions; and the engineering meaning of skeleton type is that the target area is easy to disturb.

[0065] According to an embodiment of the present invention, the method for calculating the soil structure correction coefficient includes: calculating the soil structure correction coefficient by weighting the median particle size, effective particle size, and fine particle content based on the soil structure type.

[0066] According to embodiments of the present invention, a soil structure correction coefficient is obtained by weighted calculation combining median particle size, effective particle size, and fine particle content. This coefficient quantifies the soil particle size distribution characteristics, fine particle blocking effect, and the influence of ultrafine particles on sound propagation into a comprehensive index. This correction coefficient provides a basis for setting subsequent ultrasonic excitation parameters, vacuum negative pressure parameters, and gas introduction parameters, enabling the adjustment of process parameters to match the physical properties of different soil structures. This helps improve the uniformity and controllability of mineralization reactions under multi-field coupling conditions.

[0067] In some specific embodiments, this invention introduces empirical correction coefficients η for different soil structure types to reflect the influence of soil particle size distribution and fine particle content on the acoustic field-seepage-mineralization coupling behavior within the target area. Specifically, the empirical correction coefficient η for fine-grained soils is 0.9–1.5; for transitional soils, it is 0.7–0.9; and for skeletal soils, it is 0.3–0.7. More specifically, the formula for calculating the empirical correction coefficient η is as follows (2).

[0068] .

[0069] Where: D 10 λ1 represents the effective particle size, specifically the diameter of particles with a throughput of less than 10%. FC represents the fine particle content. λ1 is the particle size effect weighting coefficient, used to characterize the influence of the effective particle size on the soil pore structure and seepage channel scale; λ2 is the fine particle retardation effect weighting coefficient, used to characterize the influence of fine particle content on pore blockage, specific surface area, and mass transfer resistance; λ3 is the structural synergistic regulation weighting coefficient, used to characterize the comprehensive influence of particle size distribution (i.e., the synergy of coarse and fine particles) on the spatial distribution and structural stability of mineralized sediments. Specifically, the values ​​of λ1, λ2, and λ3 for fine-grained soils are 0.15~0.3, 0.45~0.6, and 0.3~0.45, respectively; for transitional soils, the values ​​are 0.3~0.45, 0.25~0.4, and 0.2~0.35, respectively; and for skeletal soils, the values ​​are 0.45~0.6, 0.1~0.25, and 0.1~0.2, respectively.

[0070] Then, η is normalized using the following formula (3) to obtain the soil structure correction coefficient, denoted as . .

[0071] .

[0072] Where, η max and η min These correspond to extreme states where soil structure affects seepage and mass transfer processes, and are used to achieve a unified and normalized expression of structural effects under different soil conditions. Specifically, η max This represents the value of η corresponding to the maximum hindering effect of the soil structure on multi-field coupling effects (seepage, acoustic field, mass transfer) within the research scope. min This represents the value of η that minimizes the hindering effect of the soil structure on multi-field coupling within the scope of the study. More specifically, η max With η min The upper and lower limits of the empirical correction coefficient n are respectively taken as the range of soil types under consideration.

[0073] That is: η max =nmax (Upper limit for fine-grained soil structure, such as 1.5); η min =n min (Lower limit of skeletal soil structure, such as 0.3).

[0074] According to an embodiment of the present invention, the ultrasonic excitation system is a two-stage working mode (e.g., 30min + 30min) including a seepage induction stage and a deposition orientation stage, with a smooth transition between the two stages via a linear ramp function of 50-10min; wherein, the seepage induction stage adopts a continuous ultrasonic mode, and the deposition orientation stage adopts a pulsed ultrasonic mode.

[0075] According to an embodiment of the present invention, the seepage induction stage employs a continuous ultrasonic mode, which can continuously generate cavitation effects and micro-scale disturbances under negative pressure traction, promoting the uniform migration of the reinforcement solution in the soil pores and avoiding local stagnation. The deposition orientation stage switches to a pulsed ultrasonic mode, intermittently applying ultrasonic energy to inhibit the disordered growth and agglomeration of calcium carbonate crystals while guiding the reinforcement products to preferentially deposit towards the pore walls and particle contact sites. A linear ramp function is used for a smooth transition between the two stages, avoiding the impact of abrupt changes in ultrasonic parameters on the soil structure and ensuring the stability of the sound field switching process.

[0076] According to an embodiment of the present invention, the operating parameters of the ultrasonic excitation system include a target amplitude and a target power; the target amplitude is obtained by nonlinearly correcting the reference power of the ultrasonic excitation component 21 with a soil structure correction coefficient; the target power is obtained by linearly correcting the reference amplitude of the ultrasonic excitation component 21 with a soil structure correction coefficient.

[0077] According to an embodiment of the present invention, the operating parameters of the ultrasonic excitation system include a target amplitude and a target power, which are respectively correlated with the soil structure correction coefficient through different correction methods. The target amplitude is obtained by nonlinearly correcting the reference power of the ultrasonic excitation component 21. This nonlinear correction process is adaptively adjusted according to changes in soil structure characteristics. When the fine particle content increases or the particle size decreases, the amplitude is nonlinearly amplified to enhance the disturbance capability at the pore scale; when the particle structure is coarser, the amplitude growth tends to be gradual to avoid excessive disturbance to the soil structure. The target power is obtained by linearly correcting the reference amplitude of the ultrasonic excitation component 21. This linear correction process matches the ultrasonic energy output with the soil conditions. By correcting separately, suitable combinations of acoustic field parameters can be obtained under different soil conditions, which helps to improve the matching degree between ultrasonic excitation and soil structure.

[0078] In some specific embodiments, the target amplitude (A) is calculated using the following formula (4).

[0079] .

[0080] Where A0 is the reference amplitude, representing the initial vibration amplitude of the ultrasonic excitation system under standard reference soil conditions (medium particle size, moderate fine particle content, no significant hindrance effect), used to provide the basic acoustic field energy input and maintain the minimum required level for cavitation effects and microscale disturbances in pore water; specifically, A0 is 6-12 μm. α is a first-order linear regulation coefficient, used to characterize the soil structure correction coefficient. The linear effect on amplitude controls the response sensitivity; specifically, α is 0.6–1.0. β is the second-order nonlinear enhancement coefficient, used to characterize... The nonlinear amplification effect on amplitude reflects the additional energy compensation required to overcome pore blockage, sound attenuation and local energy dissipation under conditions of high fine particle content or confined pores; specifically, β is 0.3-0.6.

[0081] In some more specific embodiments, if A larger amplitude indicates a complex soil structure or a high proportion of fine particles within the target area, necessitating an increase in the actual amplitude, and at a higher level... The range needs to provide smooth nonlinear adjustment to avoid abrupt amplitude changes that could disturb the soil structure.

[0082] In some specific embodiments, the target power is calculated using the following formula (5).

[0083] .

[0084] Wherein, P0 is the reference power, representing the initial energy input level required by the ultrasonic excitation system under reference soil conditions (medium particle size, moderate fine particle content, no significant blocking effect); specifically, P0 is 800-1000W. γ is the structural response amplification factor, used to characterize the sensitivity of the soil structure correction factor to the adjustment of ultrasonic power demand, reflecting the energy loss compensation demand caused by factors such as the complexity of soil pore structure, fine particle blocking effect, and enhanced sound wave attenuation; specifically, γ is 1.0–2.0.

[0085] In some more specific embodiments, the purpose of the seepage induction phase (0-30 min) is to promote uniform migration of the reinforcement solution under negative pressure. The mode is continuous ultrasound with a duty cycle of 100%, and the first actual working amplitude A1 during this phase is 0.7A.

[0086] In some more specific embodiments, the purpose of the directional deposition stage (30-60 min) is to suppress crystal agglomeration and enhance directional deposition of pore walls. The mode is pulsed ultrasound, and the formula for calculating the ultrasound duty cycle is as follows (6).

[0087] .

[0088] Among them, D0 is 60%–80%; the second actual working amplitude A2 within this stage is A.

[0089] In some more specific embodiments, a lower amplitude (A1=0.7A) is used in the seepage induction stage, which helps to ensure the migration capacity of the solution while avoiding excessive disturbance to the soil structure; a target amplitude (A2=A) is used in the deposition orientation stage, which helps to enhance the local cavitation effect and microscale disturbance, thereby promoting the directional deposition of mineralization products on the pore walls and particle contact sites.

[0090] According to an embodiment of the present invention, the target pressure applied by the vacuum preloading system follows a dynamic negative pressure traction path, which includes a first negative pressure stage and a second negative pressure stage corresponding to the seepage induction stage and the deposition orientation stage. The operating parameters of the vacuum preloading system include a first target pressure and a second target pressure. Specifically, in the first negative pressure stage, the vacuum degree of the vacuum preloading system increases linearly from its initial value to the first target pressure over time; in the second negative pressure stage, the vacuum degree of the vacuum preloading system increases exponentially over time from the first target pressure and gradually approaches the second target pressure. When the vacuum degree reaches the first target pressure, the system switches from the first negative pressure stage to the second negative pressure stage.

[0091] According to an embodiment of the present invention, in the first negative pressure stage, the vacuum degree operates in a linear growth manner, which is beneficial for providing a gradually increasing negative pressure driving force during the seepage induction stage. Combined with continuous ultrasonic mode, this promotes the uniform migration of the reinforcement solution in the soil pores and avoids sudden negative pressure changes that could impact the soil structure. In the second negative pressure stage, the negative exponential growth manner gradually slows down the increase in negative pressure, enabling the maintenance of a stable negative pressure environment during the deposition orientation stage. Combined with pulsed ultrasonic mode, this guides the deposition of mineralization products towards the pore walls, preventing excessively high negative pressure gradients from disturbing the already formed mineralized structure.

[0092] According to an embodiment of the present invention, when the vacuum level reaches the first target pressure, the system switches from the first negative pressure stage to the second negative pressure stage. This switching condition is coordinated with the stage switching of the ultrasonic excitation system, achieving temporal synergy between negative pressure loading and acoustic field action.

[0093] In some specific embodiments, the target pressure (V) of the vacuum pre-compression system max The calculation formula for ) is shown in equation (7) below.

[0094] .

[0095] Among them, the maximum vacuum degree V max=Basic negative pressure + linear drive + nonlinear reinforcement. V0 represents the reference vacuum level, indicating the basic negative pressure level required to achieve stable drainage and consolidation under reference soil conditions (good pore connectivity, moderate fine particle content). 30-40 kPa is the basic negative pressure range for establishing effective drainage channels in the initial stage of vacuum preloading. μ1 is the linear structural response coefficient, used to characterize the soil structure correction coefficient. The first-order effect on vacuum requirements reflects the additional negative pressure demand caused by factors such as increased pore structure and reduced permeability. V0 is 30-40 kPa; μ1 = 15-25 kPa; μ2 = 10-20 kPa.

[0096] In some specific embodiments, the transition from the first negative pressure stage to the second stage must satisfy at least one of the following conditions.

[0097] (1) The vacuum degree reaches V=κV max .

[0098] (2) The drainage rate drops to 30%-50% of the initial peak.

[0099] Wherein, κ is the threshold coefficient for the transition from the first negative pressure stage to the second negative pressure stage, used to characterize the critical state of the transition from the "seepage-dominated stage" to the "depositional stability stage" during the vacuum preloading process; its physical meaning is: reflecting the level of negative pressure ratio when the drainage channel changes from a highly efficient connected state to a restricted or stable state under the current soil structure and seepage conditions.

[0100] According to an embodiment of the present invention, the first target pressure and the second target pressure are obtained by correcting the reference vacuum degree of the vacuum preloading system with a soil structure correction factor. The first target pressure is less than the second target pressure.

[0101] According to an embodiment of the present invention, the calculation method of the first target pressure and the second target pressure enables the application of vacuum negative pressure to match the soil structure characteristics. The soil structure correction coefficient reflects the influence of factors such as soil particle size distribution and fine particle content on negative pressure transmission and seepage behavior. By correcting the reference vacuum degree with this coefficient, the target pressure value can be adapted to the negative pressure requirements under different soil conditions. The first target pressure is lower than the second target pressure, which is coordinated with the two-stage working mode of the ultrasonic excitation system: a relatively low vacuum degree is used in the first negative pressure stage, which helps to avoid premature blockage of local channels due to excessive negative pressure in the seepage induction stage; a relatively high vacuum degree is used in the second negative pressure stage, which can provide a stable negative pressure environment in the deposition orientation stage, guide the mineralization reaction medium to migrate in the drainage direction, and maintain the stability of the formed mineralized structure.

[0102] In some specific embodiments, in the first negative pressure stage (0≤t≤t1), the calculation method of the first target pressure V(t1) is shown in the following formula (8).

[0103] .

[0104] Wherein: , κ is 0.4-0.6, t0 is the operating time counted from the start of the first negative pressure stage, and t1 is the set duration of the first negative pressure stage.

[0105] In some specific embodiments, in the second negative pressure stage (t1<t≤t2), the calculation method of the second target pressure V(t2) is shown in the following formula (9).

[0106] .

[0107] Wherein: t2 is the set time of a single cycle, ω is used to control the approach rate of the vacuum degree to the target value, and the system gradually approaches the stable value V from the initial state max . At the initial stage: V(t) and V max have a large difference. As time goes by, the difference between the two becomes smaller and smaller, and finally tends to be stable (without sudden change). When ω is large, e -ωt decays rapidly, and when approaching Vmax, rapid loading is performed; specifically, ω=0.05-0.15min -1 .

[0108] According to an embodiment of the present invention, the target introduction flow rate of carbon dioxide is obtained according to the soil structure correction coefficient and the calcium source content in the reinforcement solution; the target introduction flow rate of ammonia gas is twice the target introduction flow rate of carbon dioxide.

[0109] According to the embodiment of the present invention, the calculation method of gas flow rate enables the gas introduction amount to match the soil condition and the total amount of reactants. The soil structure correction coefficient reflects the influence of factors such as soil particle gradation and fine particle content on gas diffusion and reaction efficiency. By correcting the carbon dioxide flow rate through this coefficient, the gas injection amount can adapt to the mass transfer requirements under different soil conditions. Setting the ammonia gas flow rate to twice the carbon dioxide flow rate corresponds to the requirement of the alkaline environment provided by dissolved ammonia in the biomimetic mineralization reaction, which is conducive to providing a suitable pH condition for the conversion of carbon dioxide into carbonate ions. By determining the gas flow rate based on soil structure characteristics and calcium source content respectively, the present invention can ensure sufficient mineralization reaction while avoiding resource waste or uneven local reaction caused by excessive gas injection.

[0110] In some specific embodiments, the target introduction flow rate of carbon dioxide ( ) is calculated by the following formula (10).

[0111] .

[0112] in, N represents the total amount of carbon dioxide introduced, and N is the set number of cycles.

[0113] The formula for calculating the total amount of carbon dioxide introduced is shown in equation (11).

[0114] .

[0115] in, This is a gas correction factor used to characterize the differences in CO2 gas migration, dissolution, and participation in mineralization reactions within pores under different soil structures; that is, the effective transport and reaction participation capacity of CO2. Specifically, for fine-grained soils... The value ranges from 0.6 to 0.85; transitional soil. The value range is 1.0-1.1; skeletal soil The value range is 0.85-1.0. η r This is the calcium ion correction factor, used to characterize Ca. 2+ The effective participation of calcium ions in soil pores, i.e., the "proportion of calcium ions actually participating in the mineralization reaction," has the physical meaning of reflecting the loss of calcium ions due to factors such as adsorption, precipitation loss, and limited mass transfer. 2+ The degree of reduction in effective utilization; specifically, η r It is 0.6-0.9. (C) Ca This represents the concentration of calcium chloride solution. Unit: mol / L; V inj The total injected volume is expressed in liters (L).

[0116] In some specific embodiments, the amount of ammonia gas is calculated to be twice that of carbon dioxide based on the chemical reaction formula, that is, the total amount of ammonia gas introduced ( ) represents the total amount of carbon dioxide introduced ( The target ammonia introduction flow rate is twice that of ( ). ) to introduce flow rates for the target carbon dioxide ( Twice as much as 1.

[0117] In some specific embodiments, gas injection is stopped, and the vacuum pre-compression system is raised to the design vacuum level (80-100 kPa) to enter the conventional drainage consolidation stage. Through multiple cycles, a mineralized cemented zone with permeability stability is gradually formed around the drainage board 20, which inhibits the migration of fine particles while maintaining pore connectivity, effectively reducing the risk of channel blockage during subsequent consolidation.

[0118] According to an embodiment of the present invention, the biomimetic mineralization soil reinforcement method further includes: step (4): detecting the characteristic value of the bearing capacity of the reinforced second foundation (f ak,after ) and second deformation modulus (Es,after Under the condition that the characteristic value of the second foundation bearing capacity is not less than 1.5 times the characteristic value of the first foundation bearing capacity, and / or the second deformation modulus is not less than 2 times the first deformation modulus, a biomimetic mineralization soil reinforcement method is completed.

[0119] According to an embodiment of the present invention, step (4) provides a clear quantitative standard for judging the reinforcement effect. By comparing the characteristic value of the bearing capacity and the deformation modulus of the reinforced foundation with the initial values ​​before reinforcement, it is possible to objectively evaluate whether the reinforcement treatment has achieved the expected goal. Setting the condition that the characteristic value of the bearing capacity is increased by more than 1.5 times and the deformation modulus is increased by more than 2 times reflects the quantitative requirements for the reinforcement effect. If the conditions in step (4) are not met, secondary adjustment is performed by re-detecting and increasing the target amplitude of the ultrasonic excitation corresponding to the soil structure correction coefficient or extending the pulse action time of the deposition orientation stage.

[0120] According to an embodiment of the present invention, step (4) further includes: performing a crystal distribution test on calcium carbonate; if it is found that the calcium carbonate crystals have agglomerated, the crystals are broken up by adjusting the conditions of the ultrasonic excitation system to prevent blockage.

[0121] According to embodiments of the present invention, crystal distribution testing allows for real-time monitoring of the morphology and distribution of calcium carbonate crystals during the mineralization reaction, enabling timely detection of crystal agglomeration. When agglomeration is detected, adjusting the ultrasonic excitation conditions for fragmentation disperses and refines the formed agglomerates, preventing them from forming concentrated blockages in drainage channels or pore throats. This feedback adjustment mechanism keeps the morphology and size of the mineralization products within a controllable range, helping to ensure the connectivity of soil pores during reinforcement while maintaining the effectiveness of mineralization cementation.

[0122] It should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are all within the scope of protection of the present invention.

[0123] Example 1

[0124] This embodiment selects a coastal reclamation soft soil foundation treatment project as the application object. The soil density in the target area is 1.6 g / cm³. 3 The target area is approximately 600m². 2 The foundation soil is mainly composed of silty clay, the groundwater level is about 0.8m deep, the soil is saturated, and the proposed treatment depth is 5 meters.

[0125] Step S101: Detection

[0126] The characteristic value of the first foundation bearing capacity in the target area was 75 kPa and the first deformation modulus was 13 MPa, obtained through load tests or static cone penetration tests.

[0127] The particle characteristics of representative soil layers within the target area were obtained through indoor sieve analysis and laser particle size analysis. Among them, the median particle size D... 50 The effective particle size D is 0.038 mm. 10 The particle size is 0.004 mm, and the fine particle content (FC) is 75%.

[0128] Based on the characteristics of particle composition, the soil structure type of the target area is determined to be fine-grained.

[0129] Polyacrylic acid (PAA) was selected as the biomimetic modifier, and the concentration of calcium chloride was set at 0.5 mol / L. The reinforcement solution consisted of 10 g / L PAA and 960 m 3 The calcium chloride solution was used. The reinforcement solution was circulated and injected 15 times.

[0130] Based on experience, the values ​​of λ1, λ2, and λ3 are set to 0.23, 0.5, and 0.38 respectively, and the calculated empirical correction coefficient η is 0.90. It is 0.50.

[0131] λ is set based on experience. CO2 =0.7, calcium ion correction factor η r It is 0.75.

[0132] Step S102: Deploy the system

[0133] The vacuum preloading system is constructed using conventional vacuum preloading technology: a 0.4m thick medium-coarse sand cushion layer 19 is laid inside the dike 14 as a horizontal drainage layer; drainage boards 20 are installed using a board-inserting machine, with a spacing of 1.0m × 1.0m, forming a vertical drainage channel; vacuum filter pipes 18 are installed inside the sand cushion layer 19 and connected to the main pipeline; a sealing trench 15 is set around the perimeter and a sealing membrane 17 is laid, connected to a vacuum pump 16 to form a negative pressure system. Ultrasonic excitation components 21, in the same number as the vertical drainage boards 20, are installed at a 45° axial angle along the depth direction of the drainage boards 20.

[0134] Step S103: Injection of fluid

[0135] While maintaining the vacuum preloading system in a dynamic negative pressure state, the pumping unit is activated to inject a reinforcing solution into the soil surrounding the drainage board 20 via the ultrasonic excitation component 21. Simultaneously, the ultrasonic excitation source is turned on to form a water-based ultrasonic field in the injection area.

[0136] The parameter settings for the ultrasonic excitation system are as follows.

[0137] Set the target frequency of ultrasonic excitation to 38kHz, A0 to 8μm, α to 0.8, and β to 0.45, and the calculated target amplitude A is 12.1μm. The reference power P0 of ultrasound is 900W, γ=1.5, and the calculated P u is 1578W.

[0138] The ultrasonic mode adopts a two-stage time path (30min+30min). During the switching of ultrasonic modes, a 10min linear ramp function is used for smooth transition of amplitude and power.

[0139] In the seepage induction stage (0-30min), the mode is continuous ultrasound with a duty cycle of 100%, and the first actual working amplitude A1 is 8.48.

[0140] In the deposition orientation stage (30-60min), the mode is pulsed ultrasound, the duty cycle D0 is 0.7, D is 0.35, and the second actual working amplitude A2 is 12.1.

[0141] The parameter settings for the vacuum preloading system are described below.

[0142] The reference vacuum degree V0 is 35kPa, μ1 is 20kPa, and μ2=15kPa. The calculated V max is 48.8kPa.

[0143] In the first negative pressure stage (0≤t≤t1), κ is 0.5, the calculated V(t1) is 12.2t, and V(t1)≤24.4.

[0144] In the second negative pressure stage (t1<t≤t2), the calculated V(t2) is 48.8-24.4(-e -0.1(t-t1) ). Wherein, t2 is 60min.

[0145] Set the total flow rate of calcium chloride to 1.1×10 3 L / min.

[0146] Step S104: gas injection

[0147] After the injection of the reinforcing solution is completed, the injection is stopped while maintaining vacuum negative pressure and ultrasonic excitation, and ammonia gas is introduced into the soil around the drainage board 20 in stages through the ultrasonic excitation member 21. Ammonia gas dissolves in pore water and undergoes hydrolysis reaction, so that the pH value of the local pore water system increases gradually. Wherein, the total introduced amount and total flow rate of ammonia gas are: .

[0148] After completing the construction of the alkaline environment in pore water, carbon dioxide gas is introduced into the soil through the ultrasonic excitation member 21. Carbon dioxide dissolves in pore water and is gradually converted into carbonate ions. Wherein, the total introduced amount and total flow rate of carbon dioxide are: .

[0149] Step S105: Cyclic reinforcement

[0150] Based on changes in foundation permeability and the decline in drainage efficiency, steps S103 to S104 are repeated for fifteen cycles.

[0151] Step S106: Consolidation Stage

[0152] After completing the aforementioned biomimetic mineralization soil reinforcement method based on multi-field coupling, the gas and reinforcement liquid injection system is shut down, the vacuum pre-compression system is raised to the design vacuum level (80-100 kPa), and the conventional drainage consolidation stage begins.

[0153] The characteristic value of the second foundation bearing capacity was found to be 145 kPa and the second deformation modulus was 46 MPa, which met the reinforcement conditions.

[0154] Example 2

[0155] This embodiment selects a foundation treatment project in an alluvial plain along an inland river as the application object. The foundation soil in this area is mainly formed by river transport and deposition, with sandy particles as the main component and relatively low fine particle content, and the soil skeleton structure is obvious.

[0156] The soil density within the target area is 1.7 g / cm³. 3 The target area is approximately 400m². 2 The foundation soil is mainly composed of medium sand with a small amount of silt. The groundwater level is about 1.2m deep and the soil is saturated. The proposed treatment depth is 5 meters.

[0157] Step S201: Detection

[0158] The characteristic value of the first foundation bearing capacity in the target area (obtained through load test or static cone penetration test) is 90 kPa, and the first deformation modulus is 23 MPa.

[0159] The particle characteristics of representative soil layers within the target area were obtained through indoor sieve analysis and laser particle size analysis. Among them, the median particle size D... 50 The effective particle size is 0.3 mm. 10 The particle size is 0.12 mm, and the fine particle content (FC) is 9%.

[0160] Based on the characteristics of particle composition, the soil structure type of the target area is determined to be skeletal.

[0161] Boric acid was selected as the biomimetic regulator, and the concentration of calcium chloride was set at 1 mol / L. The reinforcement solution consisted of 0.4 mol / L boric acid mixed with 340 mg / L calcium chloride solution. 3The calcium chloride solution was used. The reinforcement solution was circulated and injected 10 times.

[0162] Based on experience, the values ​​of λ1, λ2, and λ3 are set to 0.5, 0.2, and 0.15 respectively, and the calculated empirical correction coefficient η is 0.48. It is 0.15.

[0163] λ is set based on experience. CO2 =1, calcium ion correction factor η r It is 0.75.

[0164] Step S202: Deploy the system

[0165] In this embodiment, the layout of the vacuum preloading system and the ultrasonic excitation system is similar to that in Embodiment 1. However, compared to the fine-grained dominant granular structure region in Embodiment 1, the skeletal soil structure in Embodiment 2 has better pore connectivity and skeletal stability. Therefore, under the same treatment depth conditions, the ultrasonic excitation parameters, vacuum negative pressure path, and gas introduction flow rate can be adjusted accordingly to achieve a more efficient and uniform biomimetic mineralization reinforcement effect.

[0166] Specifically, the system is deployed according to conventional vacuum preloading technology: a 0.6m thick medium-coarse sand cushion layer 19 is laid inside the dike 14 as a horizontal drainage layer; drainage boards 20 are installed using a board-inserting machine, with a spacing of 1.0m × 1.0m, forming a vertical drainage channel; vacuum filter pipes 18 are installed inside the sand cushion layer 19 and connected to the main pipeline; a sealing trench 15 is set around the perimeter and a sealing membrane 17 is laid, connected to a vacuum pump 16 to form a negative pressure system. Ultrasonic excitation components 21, in the same number as the vertical drainage boards 20, are installed along the depth direction of the drainage boards 20 at a 45° axial direction.

[0167] Step S203: Injection of fluid

[0168] While maintaining the vacuum preloading system in a dynamic negative pressure state, the pumping unit is activated to inject a reinforcing solution into the soil surrounding the drainage board 20 via the ultrasonic excitation component 21. Simultaneously, the ultrasonic excitation source is turned on to form a water-based ultrasonic field in the injection area.

[0169] The parameter settings for the ultrasonic excitation system are as follows.

[0170] The target frequency of ultrasonic excitation was set to 38 kHz, A0 to 6 μm, α to 0.7, and β to 0.4. The calculated target amplitude A was 6.7 μm. The reference power of the ultrasound was P0 to 900 W, and γ to 1.2. The calculated P... u It is 1059W.

[0171] The ultrasonic mode adopts a two-stage time path (30min+30min). During the switching process of the ultrasonic mode, a 5-10min linear climbing function is used for smooth transition of the amplitude and power.

[0172] In the seepage-induced stage (0-30min), the mode is continuous ultrasound with a duty cycle of 100%, and the first actual working amplitude A1 is 4.7.

[0173] In the deposition orientation stage (30-60min), the mode is pulsed ultrasound, the duty cycle D0 is 0.8, D is 0.68, and the second actual working amplitude A2 is 6.7.

[0174] The parameter settings for the vacuum preloading system are described as follows.

[0175] The reference vacuum degree V0 is 30kPa, μ1 is 15kPa, μ2=10kPa. The calculated V max is 23.4kPa.

[0176] In the first negative pressure stage (0≤t≤t1), κ is 0.5, the calculated V(t1) is 13.8t, V(t1)≤16.2.

[0177] In the second negative pressure stage (t1<t≤t2), the calculated V(t2) is 32.4-13.8(-e -0.1(t-t1) ). Wherein, t2 is 60min.

[0178] The total flow rate of calcium chloride is set to 5.7×10 2 L / min.

[0179] Step S204: Gas injection

[0180] After the injection of the reinforcing solution is completed, the injection is stopped while maintaining the vacuum negative pressure and ultrasonic excitation, and ammonia gas is introduced in stages into the soil around the drainage plate 20 through the ultrasonic excitation member 21. Ammonia dissolves in pore water and undergoes hydrolysis reaction, so that the pH value of the local pore water system increases gradually. Wherein, the total introduced amount and total flow rate of ammonia gas are as follows: .

[0181] After completing the construction of the alkaline environment in pore water, carbon dioxide gas is introduced into the soil through the ultrasonic excitation member 21. Carbon dioxide dissolves in pore water and is gradually converted into carbonate ions. Wherein, the total introduced amount and total flow rate of carbon dioxide are as follows: .

[0182] Step S205: Cyclic reinforcement

[0183] According to the change of foundation permeability and the attenuation of drainage efficiency, steps S203 to S204 are repeated for ten cycles.

[0184] Step S206: Consolidation Stage

[0185] After completing the aforementioned biomimetic mineralization soil reinforcement method based on multi-field coupling, the gas and reinforcement liquid injection system is shut down, the vacuum pre-compression system is raised to the design vacuum level (80–100 kPa), and the conventional drainage consolidation stage is entered.

[0186] The characteristic value of the second foundation bearing capacity was found to be 160 kPa and the second deformation modulus was 54 MPa, which met the reinforcement requirements.

[0187] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic soil mineralization reinforcement method based on multi-field coupling, characterized in that, Includes the following steps: Step (1): Test the soil in the target area, determine the soil structure type based on the test results, and calculate the soil structure correction factor, gas correction factor and calcium ion correction factor; Step (2): Vacuum preloading system and ultrasonic excitation system are deployed at intervals in the target area. The working parameters of the vacuum preloading system and ultrasonic excitation system are set based on the soil structure type and the soil structure correction coefficient. The vacuum preloading system and ultrasonic excitation system are turned on in sequence. A reinforcement solution containing calcium source and biomimetic crystal form regulator is injected into the target area so that the reinforcement solution is uniformly diffused under the action of the water-based ultrasonic field formed in the target area. Step (3): Stop injecting the reinforcement solution. According to the amount of reinforcement solution used and the gas correction coefficient and calcium ion correction coefficient, inject ammonia and carbon dioxide sequentially into the water-based ultrasonic field. The carbon dioxide is converted into carbonate ions in the ammonia atmosphere and undergoes a biomimetic mineralization reaction with the reinforcement solution to generate calcium carbonate, thereby reinforcing the target area; wherein, The test results include the first characteristic value of the foundation bearing capacity and the first deformation modulus of the target area before reinforcement, as well as the fine particle content, median particle size and effective particle size of the sand particles in the target area. The fine particle content is the mass fraction of the sand particles with a particle size of less than 0.075 mm, and the effective particle size is the particle size when the cumulative particle size distribution number of the sand particles reaches 10% of the mass. The soil structure types include fine-grained, transitional, and skeletal types, among which... The fine-grained type has a fine-grain content greater than 50% and a median particle size of less than 0.02 mm; The transitional type has a fine particle content of 20% to 50% and a median particle size of 0.02 mm to 0.075 mm; The skeletal type has a fine particle content of less than 20% and a median particle size of greater than 0.75 mm; Step (4): Detect the characteristic value of the bearing capacity and the second deformation modulus of the reinforced second foundation, and perform crystal distribution testing on the calcium carbonate; The biomimetic mineralization soil reinforcement method is completed under the condition that the characteristic value of the second foundation bearing capacity is not less than 1.5 times the characteristic value of the first foundation bearing capacity, and / or the second deformation modulus is not less than 2 times the first deformation modulus. If the calcium carbonate crystals are found to be agglomerated, the crystals are broken up by adjusting the conditions of the ultrasonic excitation system to prevent blockage.

2. The biomimetic soil mineralization reinforcement method based on multi-field coupling according to claim 1, characterized in that, The method for calculating the soil structure correction factor includes: The soil structure correction coefficient is obtained by weighting the median particle size, the effective particle size, and the fine particle content based on the soil structure type.

3. The biomimetic soil mineralization reinforcement method based on multi-field coupling according to claim 2, characterized in that, The ultrasonic excitation system operates in a two-stage mode, comprising a seepage induction stage and a deposition orientation stage, with a smooth transition between the two stages via a linear ramp function. The seepage induction stage employs continuous ultrasonic mode, while the deposition orientation stage employs pulsed ultrasonic mode.

4. The biomimetic soil mineralization reinforcement method based on multi-field coupling according to claim 3, characterized in that, The operating parameters of the ultrasonic excitation system include the target amplitude and the target power; The target amplitude is obtained by nonlinearly correcting the reference power of the ultrasonic excitation system using the soil structure correction coefficient; The target power is obtained by linearly correcting the reference amplitude of the ultrasonic excitation system using the soil structure correction factor.

5. The biomimetic soil mineralization reinforcement method based on multi-field coupling according to claim 4, characterized in that, The target pressure applied by the vacuum preloading system follows a dynamic negative pressure traction path, which includes a first negative pressure stage and a second negative pressure stage corresponding to the seepage induction stage and the deposition orientation stage. The operating parameters of the vacuum pre-compression system include a first target pressure and a second target pressure; wherein... During the first negative pressure stage, the vacuum degree of the vacuum pre-compression system increases linearly from the initial value to the first target pressure over time; In the second negative pressure stage, the vacuum degree of the vacuum pre-compression system increases exponentially with time from the first target pressure and gradually approaches the second target pressure. When the vacuum level reaches the first target pressure, the system switches from the first negative pressure stage to the second negative pressure stage.

6. The biomimetic soil mineralization reinforcement method based on multi-field coupling according to claim 5, characterized in that, The first target pressure and the second target pressure are obtained by correcting the reference vacuum degree of the vacuum preloading system with the soil structure correction coefficient; Wherein, the first target pressure is less than the second target pressure.

7. The biomimetic soil mineralization reinforcement method based on multi-field coupling according to claim 2, characterized in that, The target carbon dioxide introduction flow rate is obtained based on the gas correction coefficient and the calcium source content in the reinforcement solution. The target ammonia flow rate is twice the target carbon dioxide flow rate.

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