A method for preparing a foundation soil and rock anti-seepage solidification agent

Abstract

This invention provides a method for preparing a foundation soil and rock anti-seepage solidification agent, relating to the field of geotechnical engineering reinforcement technology. The method includes the following steps: S1. Preparing a biomimetic mineralization base liquid; S2. Preparing a slow-release initiator; S3. Preparing an ion trapping agent; S4. In-situ gradient solidification. By completely abandoning calcium chloride and replacing it with aluminum sulfate and modified retardant soil, the layered hydrotalcite phase reduces the chloride ion migration coefficient to below 500 coulombs, fundamentally blocking the electrochemical corrosion path of chloride ions on building steel bars, avoiding soil salinization. The zinc / magnesium ions intercalated in the modified retardant soil layers in-situ generate hydrotalcite nano-bandages in an alkaline environment, filling micro-cracks in the soil. This not only physically seals pores but also permanently locks in harmful free ions through ion exchange, achieving long-term ecological protection. Furthermore, the formation of Si-O-Al covalent bonds through polyaspartic acid hybrids replaces chloride ions for coagulation, achieving early skeleton reinforcement in a completely chloride-free environment.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering reinforcement technology, specifically to a method for preparing a foundation soil and rock anti-seepage solidification agent. Background Technology

[0002] The foundation refers to the soil or rock mass that supports the foundation of a building. As the foundation of a building structure, its stability directly determines the safety and durability of the superstructure. In civil engineering, the foundation soil and rock we usually deal with are not ideal homogeneous materials, but a three-phase system composed of solid particles, pore water, and gas. Foundation soil and rock anti-seepage curing agent is a chemical preparation that binds loose soil into a whole material through chemical action. At present, the mainstream technical routes are divided into inorganic, organic, and composite types. Inorganic curing agents are represented by cement, lime, fly ash, and sodium silicate. The principle is to use sodium silicate to react with calcium ions in a volcanic ash reaction to generate calcium silicate gel to fill the pores. Organic curing agents are represented by epoxy resin and unsaturated polyester resin. They have strong adhesion and good waterproof properties. Composite curing agents attempt to combine inorganic and organic materials.

[0003] Existing methods for preparing foundation soil and rock seepage prevention and solidification agents still have some problems. Traditional solidification agents use a large amount of calcium chloride as an early strength agent. Excessive chloride ions can not only corrode building steel bars, but also migrate in the soil, causing salinization. Therefore, those skilled in the art provide a method for preparing foundation soil and rock seepage prevention and solidification agents to solve the problems mentioned in the background art. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing a foundation soil and rock impermeable curing agent, which solves the problem that traditional curing agents use large amounts of calcium chloride as an early strength agent, and excessive chloride ions not only corrode building steel bars but also migrate in the soil, causing salinization.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a foundation soil and rock anti-seepage solidification agent, comprising the following steps: S1. Preparation of biomimetic mineralized base liquid: 15-20 parts sodium silicate, 3-5 parts nano-metakaolin, 0.5-1 parts polycarboxylate superplasticizer, and 1-2 parts polyaspartic acid-silane coupling agent hybrid are mixed by weight; wherein, the hybrid is prepared by side-linking γ-aminopropyltriethoxysilane with polyaspartic acid, and the solid content of the mixed system is controlled to be 35%-45%, and the pH value is 11.5-12.5; S2. Preparation of sustained-release initiator: by weight, 30-50 parts of unsaturated polyester resin, 5-8 parts of cage-type polysilsesquioxane modified maleic anhydride, 1-2 parts of benzoyl peroxide and 2-4 parts of pH-responsive microcapsules are mixed, wherein the grafting rate of POSS in the POSS-MA is 15%-20%, and polyether flexible segments with a number average molecular weight of 400-600 are introduced into the molecular chain. S3. Prepare an ion trapping agent by mixing 10-15 parts aluminum sulfate, 3-5 parts modified retardant, and 1-2 parts organosilicon waterproofing agent by weight, wherein the interlayer spacing of the modified retardant is increased to 2.0-2.5 nm. S4. In-situ gradient solidification: The biomimetic mineralization base liquid component and the slow-release initiator component are injected into the soil layer through a two-liquid grouting system at a volume ratio of 1:(0.8-1.2). Subsequently, the ion capture agent component is cut in through high-pressure rotary jetting, and the aluminum ions react with silicates to form an interpenetrating network structure.

[0006] Preferably, the preparation and mechanism of action of the polyaspartic acid-silane coupling agent hybrid in step S1 are as follows: Polyaspartic acid with a molecular weight of 2000-4000 was heated to 75-85℃ under nitrogen protection, and γ-aminopropyltriethoxysilane was added dropwise. The reaction was carried out at a constant temperature for 4-6 hours. After hydrolysis in the biomimetic mineralization base liquid component, the silanol groups of the hybrid undergo a de-alcohol condensation reaction with the aluminum hydroxyl groups on the surface of nano-metakaolin to form a Si-O-Al chemical bond bridge. The bond energy of this chemical bond is greater than that of conventional physical adsorption, thereby improving the early skeleton strength. Using this hybrid as a molecular bridge, it is endowed with an amphiphilic structure through a grafting reaction at 75-85℃. After hydrolysis in the alkaline base liquid, the silanol group at one end can undergo a de-alcohol condensation reaction with the aluminum hydroxyl groups on the surface of nano-metakaolin to form a Si-O-Al covalent bridge with a bond energy as high as 443 kJ / mol. Compared with the existing technology that relies solely on physical adsorption or van der Waals forces, the advantage of this chemical bonding is that it firmly anchors the solidifier to the soil skeleton, making it less prone to detachment even under groundwater erosion or dynamic loads. This significantly improves the early skeleton strength and water dispersibility of the foundation, solving the problem of the solidifier being easily diluted and lost in water-rich soft strata.

[0007] Preferably, the preparation and mechanism of action of the polyaspartic acid-silane coupling agent hybrid in step S1 are as follows: Polyaspartic acid with a molecular weight of 2000-4000 was heated to 75-85℃ under nitrogen protection, and γ-aminopropyltriethoxysilane was added dropwise. The reaction was carried out at a constant temperature for 4-6 hours. After hydrolysis in the biomimetic mineralized base liquid component, the silanol groups of the hybrid undergo a de-alcoholization condensation reaction with the aluminum hydroxyl groups on the surface of nano-kaolin, forming Si-O-Al chemical bonds that bridge the gap. The bond energy of these chemical bonds is greater than that of conventional physical adsorption, thereby enhancing the early skeleton strength. When POSS-MA is dispersed in an alkaline sodium silicate solution, the polyether segments undergo conformational extension, physically enveloping the silicate ion clusters like countless tiny molecular beads, generating a huge steric hindrance effect that physically blocks the contact and condensation of silicate ions. The macroscopic manifestation of this microscopic mechanism is that the viscosity of the system changes by less than 10% within 2 hours, and the rheological index remains stable in the pseudoplastic range of 0.85-0.95. Its advantage is that it gives the grout excellent pumpability, preventing sedimentation and stratification during static storage, and avoiding the defects of the acidic components causing a sharp increase in viscosity and making construction impossible, as pointed out in the original rejection decision, thus ensuring the engineering feasibility of long-distance grouting.

[0008] Preferably, the wall material of the pH-responsive microcapsules in step S2 is a polyurea-polyurethane copolymer, and 0.5-1.5 wt% of nano-montmorillonite sheets are interspersed in the gaps of the wall material network. The microcapsules have a wall thickness controlled at 1-3 μm and swell and rupture when the pH value is greater than 10.5. Before rupture, they can withstand the grouting pipeline pressure of 0.8-1.2 MPa, preventing the grout from prematurely gelling due to high pressure during transportation. 0.5-1.5 wt% of nano-montmorillonite sheets are interspersed in the polyurea-polyurethane copolymer wall material network. The sheet barrier effect of montmorillonite significantly increases the shell density, enabling it to withstand the grouting pipeline pressure of 0.8-1.2 MPa. At the same time, the chemical properties of the wall material allow it to remain dense in a storage state with pH < 10.5. Once injected into a soil layer with pH > 10.5, it swells and ruptures. The advantage of this design is that it achieves an intelligent control mode where mixing on the ground does not react, and solidification only occurs after underground injection. This effectively prevents the grout from prematurely gelling in the nozzle or pipeline, ensuring construction safety. At the same time, by controlling the release timing of the accelerator, the solidification reaction process is precisely controlled.

[0009] Preferably, zinc or magnesium ions are intercalated in the interlayer domains of the modified retto soil described in step S3. During the solidification process, zinc or magnesium ions are slowly released in the alkaline soil environment and react with silicates and aluminum ions to form zinc-aluminum hydrotalcite or magnesium-aluminum hydrotalcite phases. The layered structure of the hydrotalcite phase fills the microcracks in the soil, reducing the chloride ion migration coefficient of the solidified soil to below 500 coulombs. Using Leto soil with an intercalation treatment that expands the interlayer spacing to 2.0-2.5 nm as an "ion prison," zinc or magnesium ions intercalated in the interlayer domains undergo in-situ mineralization reactions with silicates and aluminum ions in the alkaline soil environment to generate zinc-aluminum or magnesium-aluminum hydrotalcite phases with a layered structure. This hydrotalcite phase has extremely strong anion exchange capacity, which can firmly lock free harmful ions in the interlayer and reduce the chloride ion migration coefficient of the solidified soil to an extremely low level of below 500 coulombs. This not only blocks the electrochemical corrosion path of chloride ions on building steel bars, but also fills the microcracks in the soil like a nano-band-aid, giving the foundation the ability to self-repair microcracks.

[0010] Preferably, the grouting pressure of the dual-liquid grouting system in step S4 is controlled at 0.5-1.5 MPa, and the initial setting time of the grout is controlled at 15-30 minutes. Furthermore, the unsaturated polyester resin selected is a bisphenol A type unsaturated polyester resin with an acid value of 20-35 mgKOH / g, ensuring that the wetting angle between the resin and silicate interface is less than 30 degrees, thereby improving the interfacial bonding force. Based on the synergistic effect of interfacial chemistry and rheological dynamics, a pressure range of 0.5-1.5MPa can overcome the soil pore resistance to ensure effective diffusion of the grout, while preventing soil splitting or surface heave due to excessive pressure. Combined with an initial setting time window of 15-30 minutes, it provides sufficient safety margin for construction operations. The resin with this specific acid value range is selected because the acid value directly determines the polarity and hydrophilicity of the resin molecules. The acid value of 20-35 mgKOH / g ensures that the surface tension of the resin matches that of the silicate solution, making its wetting angle with soil particles less than 30 degrees, achieving a spreading effect similar to water on a lotus leaf. Thus, while wetting the soil without dead corners, a dense bonding layer is formed with silicate through Si-OC chemical bonds, completely eliminating interfacial pores, significantly improving the impermeability level, and preventing capillary water rise.

[0011] In step S4, the high-pressure jet spraying speed is 10-20 r / min and the lifting speed is 5-15 cm / min. This allows the aluminum sulfate in the ion scavenger to react with the biomimetic mineralization base liquid to form a silica-alumina gel in the soil pores, creating a gradient structure that is dense on the outside and tough on the inside. The surface porosity is less than 5%, and the deep porosity is controlled at 15%-20%. Utilizing the difference in shear force field generated by the 10-20 r / min rotation speed and the 5-15 cm / min lifting speed, the ion scavenger is distributed in the soil with a concentration gradient that is high on the outside and low on the inside. This results in the formation of a dense silica-alumina gel waterproof layer with a porosity of less than 5% on the surface, while the deep layer retains a tough resin skeleton with a porosity of 15%-20%. The advantage of this heterogeneous structure, which is dense on the outside and tough on the inside, is that it balances the surface layer's resistance to plant root penetration and weathering, as well as the deep layer's flexibility to adapt to uneven foundation settlement. This avoids the structural cracking caused by excessive brittleness in traditional homogeneous solidified soil.

[0012] The solidified soil contains particles with microscopic core and shell structures. The core-shell structure uses modified rettoitite as the core and zinc-aluminum hydrotalcite as the shell. The soil skeleton is composed of interwoven calcium silicate whiskers with a length of 5-20 μm and an aspect ratio greater than 10. The surface of the whiskers is adsorbed with POSS-MA polyether segments to form a nano-lubricating layer. The soil spontaneously assembles to form a multi-scale reinforcing structure. That is, microscopic core-shell particles with modified rettoitite as the core and zinc-aluminum hydrotalcite as the shell are used as fillers and are interspersed in the three-dimensional skeleton composed of interwoven calcium silicate whiskers with a length of 5-20 μm and an aspect ratio greater than 10. The surface of the whiskers is adsorbed with POSS-MA polyether segments to form a nano-lubricating layer. The advantage of this microstructure is that it achieves a combination of rigidity and flexibility in mechanical properties. The calcium silicate whiskers provide high-strength support similar to steel bars, while the nano-lubricating layer and core-shell particles endow the material with certain slip and deformation capabilities, so that the foundation does not undergo brittle fracture under heavy loads, which greatly improves the safety reserve of the foundation.

[0013] (III) Beneficial Effects This invention provides a method for preparing a foundation soil and rock anti-seepage solidification agent. It has the following beneficial effects: 1. In this invention, calcium chloride is completely abandoned, and aluminum sulfate and modified rettoiter are used in combination to reduce the chloride ion migration coefficient to below 500 coulombs by utilizing the layered hydrotalcite phase, which fundamentally blocks the electrochemical corrosion path of chloride ions on building steel bars and avoids soil salinization.

[0014] 2. In this invention, zinc / magnesium ions intercalated between modified soil layers generate hydrotalcite nano-bandages in situ in an alkaline environment, filling micro-cracks in the soil. This not only physically seals the pores but also permanently locks in harmful free ions through ion exchange, achieving long-term ecological protection.

[0015] 3. In this invention, Si-O-Al covalent bonds formed by polyaspartic acid hybrids replace chloride ions to promote coagulation, thereby achieving early skeleton reinforcement in a completely chloride-free environment and solving the problem of later strength reduction caused by excessive chloride ions in traditional curing agents.

[0016] 4. In this invention, the heterogeneous structure with a dense outer layer and a tough inner layer physically isolates the invasion of external salts, while the internal core-shell structure adsorbs and fixes internal free ions. This dual protection completely eliminates the risk of steel corrosion and soil degradation caused by chloride ion migration. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: This invention provides a method for preparing a foundation soil and rock impermeable solidifying agent, comprising the following steps: S1. Preparation of biomimetic mineralized base solution: By weight, mix 15-20 parts of sodium silicate, 3-5 parts of nano-metakaolin, 0.5-1 parts of polycarboxylate superplasticizer, and 1-2 parts of polyaspartic acid-silane coupling agent hybrid. The hybrid is prepared by side-linking γ-aminopropyltriethoxysilane with polyaspartic acid. The solid content of the mixture is controlled at 35%-45%, and the pH value is 11.5-12.5.

[0019] S2. Preparation of sustained-release initiator: By weight, 30-50 parts of unsaturated polyester resin, 5-8 parts of cage-type polysilsesquioxane-modified maleic anhydride, 1-2 parts of benzoyl peroxide and 2-4 parts of pH-responsive microcapsules are mixed, wherein the grafting rate of POSS in POSS-MA is 15%-20%, and polyether flexible segments with a number average molecular weight of 400-600 are introduced into the molecular chain.

[0020] S3. Prepare an ion trapping agent by mixing 10-15 parts aluminum sulfate, 3-5 parts modified retardant, and 1-2 parts organosilicon waterproofing agent by weight, thereby increasing the interlayer spacing of the modified retardant to 2.0-2.5 nm.

[0021] S4. In-situ gradient solidification: The biomimetic mineralization base liquid component and the slow-release initiator component are injected into the soil layer through a two-liquid grouting system at a volume ratio of 1:(0.8-1.2). Subsequently, the ion capture agent component is cut in through high-pressure rotary jetting, and the aluminum ions react with silicates to form an interpenetrating network structure.

[0022] The preparation and mechanism of action of the polyaspartic acid-silane coupling agent hybrid in step S1 are as follows: Polyaspartic acid with a molecular weight of 2000-4000 was heated to 75-85℃ under nitrogen protection, and γ-aminopropyltriethoxysilane was added dropwise. The reaction was carried out at a constant temperature for 4-6 hours.

[0023] After hydrolysis in the biomimetic mineralization base liquid component, the silanol groups of the hybrid undergo a de-alcoholization condensation reaction with the aluminum hydroxyl groups on the surface of nano-metakaolin, forming a Si-O-Al chemical bond bridge. The bond energy of this chemical bond is greater than that of conventional physical adsorption, thereby improving the early skeleton strength. Using this hybrid as a molecular bridge, it is endowed with an amphiphilic structure through a grafting reaction at 75-85℃. After hydrolysis in the alkaline base liquid, the silanol group at one end can undergo a de-alcoholization condensation reaction with the aluminum hydroxyl groups on the surface of nano-metakaolin, forming a Si-O-Al covalent bridge with a bond energy as high as 443 kJ / mol. Compared with the existing technology that relies solely on physical adsorption or van der Waals forces, the advantage of this chemical bonding is that it firmly anchors the solidifier to the soil skeleton, making it less prone to detachment even under groundwater erosion or dynamic loads. This significantly improves the early skeleton strength and water dispersibility of the foundation, solving the problem of the solidifier being easily diluted and lost in water-rich soft strata.

[0024] The preparation and mechanism of action of the polyaspartic acid-silane coupling agent hybrid in step S1 are as follows: Polyaspartic acid with a molecular weight of 2000-4000 was heated to 75-85℃ under nitrogen protection, and γ-aminopropyltriethoxysilane was added dropwise. The reaction was carried out at a constant temperature for 4-6 hours.

[0025] After hydrolysis in the biomimetic mineralized base liquid component, the silanol groups of the hybrid undergo a de-alcoholization condensation reaction with the aluminum hydroxyl groups on the surface of nano-kaolinite, forming Si-O-Al chemical bonds that bridge the gap. The bond energy of these chemical bonds is greater than that of conventional physical adsorption, thereby enhancing the early skeleton strength. When POSS-MA is dispersed in an alkaline sodium silicate solution, the polyether segments undergo conformational extension, physically enveloping the silicate ion clusters like countless tiny molecular beads, generating a huge steric hindrance effect that physically blocks the contact and condensation of silicate ions. The macroscopic manifestation of this microscopic mechanism is that the viscosity of the system changes by less than 10% within 2 hours, and the rheological index remains stable in the pseudoplastic range of 0.85-0.95. Its advantage is that it gives the grout excellent pumpability, preventing sedimentation and stratification during static storage, and avoiding the defects of the acidic components causing a sharp increase in viscosity and making construction impossible, as pointed out in the original rejection decision, thus ensuring the engineering feasibility of long-distance grouting.

[0026] In step S2, the wall material of the pH-responsive microcapsules is a polyurea-polyurethane copolymer, and 0.5-1.5 wt% of nano-montmorillonite sheets are interspersed in the gaps of the wall material network.

[0027] The microcapsule wall thickness is controlled at 1-3 μm, and it swells and ruptures when the pH value is greater than 10.5. Before rupture, it can withstand the grouting pipeline pressure of 0.8-1.2 MPa, preventing the grout from prematurely gelling due to high pressure during transportation. 0.5-1.5 wt% of nano-montmorillonite sheets are interspersed in the polyurea-polyurethane copolymer wall material network. The sheet barrier effect of montmorillonite significantly increases the shell density, enabling it to withstand the grouting pipeline pressure of 0.8-1.2 MPa. At the same time, the chemical properties of the wall material are utilized to keep it dense in the storage state at pH < 10.5. Once injected into the soil layer at pH > 10.5, it swells and ruptures. The advantage of this design is that it achieves an intelligent control mode of no reaction when mixed on the ground and solidification only when injected underground, effectively preventing the grout from prematurely gelling in the nozzle or pipeline, ensuring construction safety. At the same time, by controlling the release time of the accelerator, the solidification reaction process is precisely controlled.

[0028] In step S3, zinc or magnesium ions are intercalated in the interlayer domains of the modified rettos.

[0029] During the solidification process, zinc or magnesium ions are slowly released in the alkaline soil environment and react with silicates and aluminum ions to form zinc-aluminum hydrotalcite or magnesium-aluminum hydrotalcite phases. The layered structure of the hydrotalcite phase fills the microcracks in the soil, reducing the chloride ion migration coefficient of the solidified soil to below 500 coulombs. Using Leto soil with intercalation treatment to expand the interlayer spacing to 2.0-2.5 nm as an "ion prison," zinc or magnesium ions intercalated in the interlayer domains undergo in-situ mineralization reactions with silicates and aluminum ions in the alkaline soil environment to generate zinc-aluminum or magnesium-aluminum hydrotalcite phases with a layered structure. This hydrotalcite phase has extremely strong anion exchange capacity, which has the advantage of being able to firmly lock free harmful ions in the interlayer, reducing the chloride ion migration coefficient of the solidified soil to an extremely low level of below 500 coulombs. This not only blocks the electrochemical corrosion path of chloride ions on building steel bars, but also uses the layered structure to fill the microcracks in the soil like a nano-band-aid, giving the foundation the ability to self-repair microcracks.

[0030] In step S4, the grouting pressure of the dual-liquid grouting system is controlled at 0.5-1.5 MPa, and the initial setting time of the grout is controlled at 15-30 minutes.

[0031] Furthermore, the unsaturated polyester resin selected is a bisphenol A type unsaturated polyester resin with an acid value of 20-35 mgKOH / g, ensuring that the wetting angle between the resin and silicate interface is less than 30 degrees, thus improving the interfacial bonding force. Based on the synergistic effect of interfacial chemistry and rheological dynamics, a pressure range of 0.5-1.5MPa can overcome the soil pore resistance to ensure effective diffusion of the grout, while preventing soil splitting or surface heave due to excessive pressure. Combined with an initial setting time window of 15-30 minutes, it provides sufficient safety margin for construction operations. The resin with this specific acid value range is selected because the acid value directly determines the polarity and hydrophilicity of the resin molecules. The acid value of 20-35 mgKOH / g ensures that the surface tension of the resin matches that of the silicate solution, making its wetting angle with soil particles less than 30 degrees, achieving a spreading effect similar to water on a lotus leaf. This allows for thorough wetting of the soil without dead corners, while forming a dense bonding layer with silicate through Si-OC chemical bonds, completely eliminating interfacial pores, significantly improving the impermeability level, and preventing capillary water rise.

[0032] In step S4, the high-pressure jet grouting speed is 10-20 r / min and the lifting speed is 5-15 cm / min. This causes the aluminum sulfate in the ion capture agent to react with the biomimetic mineralization base liquid to form a silica-alumina gel in the soil pores, creating a gradient structure that is dense on the outside and tough on the inside. The surface porosity is less than 5%, and the deep porosity is controlled at 15%-20%. Utilizing the difference in shear force field generated by the 10-20 r / min rotation speed and the 5-15 cm / min lifting speed, the ion capture agent is distributed in the soil with a concentration gradient that is high on the outside and low on the inside. This results in the formation of a dense silica-alumina gel waterproof layer with a porosity of less than 5% on the surface, while the deep layer retains a tough resin skeleton with a porosity of 15%-20%. The advantage of this heterogeneous structure, which is dense on the outside and tough on the inside, is that it takes into account both the surface layer's resistance to plant root penetration and weathering, and the deep layer's flexible adaptability to uneven settlement of the foundation, avoiding the structural cracking caused by excessive brittleness in traditional homogeneous solidified soil.

[0033] The solidified soil contains particles with microscopic core and shell structures.

[0034] The core-shell structure uses modified rettoitite as the core and zinc-aluminum hydrotalcite as the shell. The soil skeleton is composed of interwoven calcium silicate whiskers with a length of 5-20 μm and an aspect ratio greater than 10. The surface of the whiskers is adsorbed with polyether segments of POSS-MA to form a nano-lubricating layer. The soil spontaneously assembles to form a multi-scale reinforcing structure. That is, the micro-core-shell particles with modified rettoitite as the core and zinc-aluminum hydrotalcite as the shell are used as fillers and are interspersed in the three-dimensional skeleton composed of interwoven calcium silicate whiskers with a length of 5-20 μm and an aspect ratio greater than 10. The surface of the whiskers is adsorbed with polyether segments of POSS-MA to form a nano-lubricating layer. The advantage of this microstructure is that it achieves a combination of rigidity and flexibility in mechanical properties. The calcium silicate whiskers provide high-strength support similar to steel bars, while the nano-lubricating layer and core-shell particles endow the material with certain slip and deformation capabilities, so that the foundation does not undergo brittle fracture under heavy loads, which greatly improves the safety reserve of the foundation.

[0035] Typical silty soil from a villa area, with a moisture content of approximately 55%, was used to prepare a biomimetic mineralization base solution by weight. This solution consisted of 18 parts sodium silicate (modulus 3.2), 4 parts nano-metakaolin, 0.8 parts polycarboxylate superplasticizer, and 1.5 parts polyaspartic acid-silane coupling agent hybrid (molecular weight 3000). The reaction temperature was 80℃. The solid content was controlled at 40%, and the pH value at 12.0. A slow-release initiator was then prepared by combining 40 parts bisphenol A type unsaturated polyester resin (acid value 28 mgKOH / g) and POSS-MA (grafted at 18%). An ion trapping agent was prepared by mixing 6 parts of benzoyl peroxide, 1.5 parts of benzoyl peroxide, and 3 parts of pH-responsive microcapsules with a wall thickness of 2 μm. A mixture of 12 parts of aluminum sulfate, 4 parts of zinc-intercalated modified rettoiter, and 1.5 parts of organosilicon waterproofing agent was then used. During construction, components A and B were injected into the soil layer at a volume ratio of 1:1 using a two-liquid grouting system (pressure 1.0 MPa). Subsequently, component C was rotary-jet-inserted at a lifting speed of 15 cm / min. After 28 days of curing, the unconfined compressive strength reached 4.5 MPa, the chloride ion migration coefficient was 320 coulombs, and the viscosity change rate of the grout within 2 hours was 7.8%, with no flocculation observed. Example 2: Seepage prevention and reinforcement for sandy backfill foundations A sandy backfill soil from a slope, characterized by high porosity and strong permeability, was used to prepare a biomimetic mineralization base solution. This solution consisted of 16 parts sodium silicate, 3 parts nano-kaolin, 0.5 parts polycarboxylate superplasticizer, and 1 part polyaspartic acid-silane coupling agent hybrid, with a solid content of 35% and a pH of 11.8. A slow-release initiator was prepared by mixing 35 parts unsaturated polyester resin, 5 parts POSS-MA, 1 part benzoyl peroxide, and 2 parts microcapsules containing nano-montmorillonite. An ion trapping agent was prepared by mixing 10 parts aluminum sulfate, 3 parts modified rettoiter with intercalated magnesium ions, and 1 part organosilicon waterproofing agent. During construction, high-pressure jet spraying (15 r / min) was used to react components C and A. After curing, the surface porosity was only 3.2%, and the deep porosity was 16.5%, forming a distinct dense outer and tough inner structure, with the permeability coefficient reduced to 1×10^-7. The temperature was 1000 cm / s, and due to the ion trapping effect of the modified retto soil, no free chloride ions were detected inside the soil, effectively preventing corrosion of surrounding metal pipelines.

[0036] Unless otherwise stated, all raw materials used in this technical solution are commercially available, and the specific specifications are as follows: Sodium silicate is selected from industrial-grade liquid water glass with a modulus of 3.1-3.4, a Baume degree of 38-42°Bé, a SiO2 content of ≥26%, and a Na2O content of ≥8.5%.

[0037] Nano-metakaolin is a highly active metakaolin prepared at a calcination temperature of 700-800℃, with a particle size D50 of 1-3μm and a specific surface area ≥15 m². 2 / g, Al2O3 content ≥40%.

[0038] Polyaspartic acid is selected from industrial-grade sodium polyaspartate with a molecular weight of 2000-4000 and a solid content of ≥40%.

[0039] γ-aminopropyltriethoxysilane, grade KH-550, purity ≥98%.

[0040] The modified rettolith was selected from rettolith produced in Zhongxiang, Hubei Province, which was modified by sodium ionization and had a cation exchange capacity (CEC) ≥60mmol / 100g. The interlayer spacing was expanded to 2.0-2.5nm by X-ray diffraction (XRD) (Cu target, scanning speed 2° / min).

[0041] The unsaturated polyester resin selected is bisphenol A type unsaturated polyester resin, with the acid value strictly controlled at 20-35 mgKOH / g and the viscosity (25℃) at 300-500 mPa·s.

[0042] The cage-type polysilsesquioxane (POSS) is selected from octaaminophenyl POSS with a purity ≥99%.

[0043] The test methods and evaluation standards adopted GB / T 1452—2005 for determining interlaminar peel strength, GB / T 2567—2008 for determining the flexural properties of resin castings, and ASTM D3410 for testing the compressive strength of composite materials. All samples were tested after being conditioned for 48 hours under standard conditions (23±2℃, 50±5%RH). The data were taken as the average of 5 repeated tests, and the deviation was controlled within ±3%.

[0044] The key performance indicators involved in this invention were all measured using the following national or industry standards to ensure the objectivity of the data: Unconfined compressive strength was determined according to the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), with specimen size of Φ50mm×100mm and loading rate of 1.0 mm / min.

[0045] The chloride ion migration coefficient (RCM method) is performed in accordance with Appendix B of the "Technical Specification for Corrosion Protection of Concrete Structures in Highway Engineering" (JTG / TB07-01-2006). Specifically, the solidified soil sample is cut into Φ100mm×50mm specimens, energized under a 30V DC electric field for 6 hours, and the chloride ion penetration depth is determined by silver nitrate titration. The chloride ion migration coefficient (unit: coulomb) is then calculated.

[0046] Porosity and microstructure were determined by mercury intrusion porosimetry (MIP), and the core-shell structure and whisker growth morphology inside the soil were observed by scanning electron microscopy (SEM, Hitachi SU8010).

[0047] The rheological properties of the slurry were measured using a rotational viscometer (NDJ-1 type) at a constant temperature of 25℃, and the initial viscosity and the rate of change over 2 hours were recorded.

[0048] Comparative Example 1 (Traditional Calcium Chloride Formula) Except for replacing “aluminum sulfate” in step S3 with an equal weight of “calcium chloride”, the other raw material ratios, preparation steps and curing conditions are exactly the same as in Example 1.

[0049] Results: After 28 days of curing, the chloride ion migration coefficient reached 1850 coulombs, and obvious salt blooming occurred in the soil. Three months after the steel bar test block was implanted, the surface corrosion rate exceeded 5%.

[0050] Comparative Example 2 (Bridging with missing hybrids) Except for omitting the "polyaspartic acid-silane coupling agent hybrid" in step S1 and replacing it with an equal weight of ordinary silane coupling agent KH-550, the other conditions are the same as in Example 1.

[0051] Results: In the simulation experiment of water-rich strata, the slurry was severely diluted by groundwater, the unconfined compressive strength of the solidified body was only 1.2 MPa, and obvious disintegration was observed.

[0052] Comparative Example 3 (Non-pH responsive initiation) Except for replacing the "pH-responsive microcapsules" in step S2 with directly mixed benzoyl peroxide, the other conditions are the same as in Example 1.

[0053] Result: The grout became locally gelled and blocked in the grouting pipe (pressure 0.8MPa), making long-distance pumping impossible.

[0054] It should be noted that when the solid content of the mixed system is controlled at 35% (or 45%) and the pH value is 11.5 (or 12.5), it is only necessary to adjust the grouting pressure in step S4 to 0.5MPa (or 1.5MPa) accordingly, and the technical effect of the present invention can still be achieved, with the unconfined compressive strength of the solidified soil fluctuating within ±5%.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a foundation soil and rock impermeable solidifying agent, characterized in that: Includes the following steps: S1. Preparation of biomimetic mineralized base liquid: 15-20 parts sodium silicate, 3-5 parts nano-metakaolin, 0.5-1 parts polycarboxylate superplasticizer, and 1-2 parts polyaspartic acid-silane coupling agent hybrid are mixed by weight; wherein, the hybrid is prepared by side-linking γ-aminopropyltriethoxysilane with polyaspartic acid, and the solid content of the mixed system is controlled to be 35%-45%, and the pH value is 11.5-12.5; S2. Preparation of sustained-release initiator: by weight, 30-50 parts of unsaturated polyester resin, 5-8 parts of cage-type polysilsesquioxane modified maleic anhydride, 1-2 parts of benzoyl peroxide and 2-4 parts of pH-responsive microcapsules are mixed, wherein the grafting rate of POSS in the POSS-MA is 15%-20%, and polyether flexible segments with a number average molecular weight of 400-600 are introduced into the molecular chain. S3. Prepare an ion trapping agent by mixing 10-15 parts aluminum sulfate, 3-5 parts modified retardant, and 1-2 parts organosilicon waterproofing agent by weight, wherein the interlayer spacing of the modified retardant is increased to 2.0-2.5 nm. S4. In-situ gradient solidification: The biomimetic mineralization base liquid component and the slow-release initiator component are injected into the soil layer through a two-liquid grouting system at a volume ratio of 1:(0.8-1.2). Subsequently, the ion capture agent component is cut in through high-pressure rotary jetting, and the aluminum ions react with silicates to form an interpenetrating network structure.

2. The preparation method of the foundation soil and rock anti-seepage solidification agent according to claim 1, characterized in that: The preparation and mechanism of action of the polyaspartic acid-silane coupling agent hybrid described in step S1 are as follows: Polyaspartic acid with a molecular weight of 2000-4000 was heated to 75-85℃ under nitrogen protection, and γ-aminopropyltriethoxysilane was added dropwise. The reaction was carried out at a constant temperature for 4-6 hours. After the hybrid is hydrolyzed in the biomimetic mineralization base liquid component, its silanol groups undergo a de-alcoholization condensation reaction with the aluminum hydroxyl groups on the surface of nano-kaolin to form Si-O-Al chemical bonds that bridge the gap. The bond energy of these chemical bonds is greater than that of conventional physical adsorption energy, thereby improving the early skeleton strength.

3. The preparation method of the foundation soil and rock anti-seepage solidification agent according to claim 1, characterized in that: The preparation and rheological control mechanism of POSS-MA in step S2 are as follows: Dissolve octaaminophenyl POSS in anhydrous DMF, add maleic anhydride monomer and initiator AIBN, and carry out free radical graft polymerization at 65-75℃. The polyether flexible segments in the POSS-MA undergo conformational expansion in the alkaline environment of water glass, physically encapsulating silicate ion groups, so that the viscosity of the biomimetic mineralized base liquid component changes by less than 10% within 2 hours, and the slurry rheological index is maintained in the pseudoplastic fluid range of 0.85-0.

95.

4. The preparation method of the foundation soil and rock anti-seepage solidification agent according to claim 1, characterized in that: The wall material of the pH-responsive microcapsules in step S2 is a polyurea-polyurethane copolymer, and 0.5-1.5 wt% of nano-montmorillonite sheets are interspersed in the gaps of the wall material network. The wall thickness of the microcapsules is controlled at 1-3 μm, and they swell and rupture when the pH value is greater than 10.

5. Before rupture, they can withstand the grouting pipeline pressure of 0.8-1.2 MPa to prevent the grout from gelling prematurely due to high pressure during transportation.

5. The preparation method of the foundation soil and rock anti-seepage solidification agent according to claim 1, characterized in that: The modified retto soil described in step S3 has zinc or magnesium ions intercalated in the interlayer domains. During the solidification process, the zinc or magnesium ions are slowly released in the alkaline soil environment and react with silicates and aluminum ions to form zinc-aluminum hydrotalcite or magnesium-aluminum hydrotalcite phases. The layered structure of the hydrotalcite phases fills the microcracks in the soil, reducing the chloride ion migration coefficient of the solidified soil to below 500 coulombs.

6. The preparation method of the foundation soil and rock anti-seepage solidification agent according to claim 1, characterized in that: In step S4, the grouting pressure of the dual-liquid grouting system is controlled at 0.5-1.5 MPa, and the initial setting time of the grout is controlled at 15-30 minutes. Furthermore, the unsaturated polyester resin is selected from bisphenol A type unsaturated polyester resin with an acid value of 20-35 mgKOH / g to ensure that the wetting angle between the resin and the silicate interface is less than 30 degrees, thereby improving the interfacial bonding strength.

7. The preparation method of the foundation soil and rock anti-seepage solidification agent according to claim 1, characterized in that: In step S4, the high-pressure rotary jet has a rotation speed of 10-20 r / min and an lifting speed of 5-15 cm / min, which allows the aluminum sulfate in the ion capture agent to react with the biomimetic mineralization base liquid to form a silica-alumina gel in the soil pores, creating a gradient structure that is dense on the outside and tough on the inside. The surface porosity is less than 5%, and the deep porosity is controlled at 15%-20%.

8. A method for preparing a foundation soil and rock impermeable solidifying agent according to any one of claims 1 to 7, characterized in that: The solidified soil contains particles with microscopic core and shell structures. The core and shell structure uses modified retto soil as the core and zinc aluminum hydrotalcite phase as the shell. The soil skeleton is composed of interwoven calcium silicate whiskers with a length of 5-20 μm and an aspect ratio greater than 10. The surface of the whiskers is adsorbed with polyether segments of POSS-MA to form a nano-lubricating layer.