Tunnel crack self-adaptive plugging material, preparation method and application thereof

Abstract

The present application belongs to the technical field of waterproofing and leakage stopping of underground engineering, and particularly relates to a tunnel existing crack self-adaptive leakage stopping material and a preparation method and application thereof. The tunnel existing crack self-adaptive leakage stopping material comprises component A and component B, the mass ratio of the component A to the component B is (5-8):1, the component A comprises modified epoxy emulsion 30-40 parts, functional monomer 15-25 parts, nano composite filler 8-15 parts, expansion accelerator 5-10 parts, dispersing agent 1-3 parts and deionized water 10-20 parts in terms of mass fraction, and the component B comprises latent curing agent 40-60 parts, nano catalyst 5-10 parts, slow-release carrier 20-30 parts and defoaming agent 1-2 parts in terms of mass fraction. The present application solves the technical problems that the conventional leakage stopping material is difficult to penetrate into fine cracks, is easily washed away under high-pressure water flow and has insufficient bonding strength with crack wall surface, and realizes adaptive plugging and long-acting water stopping effect for cracks with different widths and different water contents.

Description

Technical Field

[0001] This invention belongs to the field of waterproofing and leak sealing technology for underground engineering, specifically relating to an adaptive leak sealing material for existing cracks in tunnels, its preparation method and application, which is particularly suitable for sealing and repairing cracks in tunnel structures with high water content and complex geological conditions. Background Technology

[0002] During long-term operation, tunnel projects are affected by a combination of factors such as changes in geological conditions, structural stress and deformation, and fluctuations in surrounding rock pressure. Existing cracks are prone to form in the structure, which can lead to groundwater leakage. In severe cases, this can affect the stability of the tunnel structure and the safety of its operation.

[0003] To address tunnel crack leakage, existing sealing materials are mainly classified into three categories: cement-based materials, chemical grouting materials, and expandable polymers. Cement-based materials are widely used due to their low cost and ease of application, but their poor fluidity makes it difficult to penetrate deep into minute cracks, limiting their sealing effect to the surface and failing to achieve deep water stoppage. Chemical grouting materials, such as acrylamide polymers, while possessing good penetration properties, are highly toxic, posing poor environmental compatibility and significant ecological risks in underground engineering, making them unsuitable for increasingly stringent environmental protection requirements. Expandable polymers, although capable of filling cracks through volume expansion, rely primarily on a single physical expansion mechanism. Under high-pressure flowing water, these materials are easily washed away, and their adhesion strength to the crack walls is insufficient, resulting in unreliable long-term sealing effects and a high risk of secondary leakage.

[0004] In summary, existing sealing materials have varying degrees of defects in terms of fluidity, environmental friendliness, erosion resistance, and bonding strength, making it difficult to fully meet the long-term sealing requirements of tunnel cracks under complex geological conditions. Summary of the Invention

[0005] To address the problems in existing technologies, this invention provides an adaptive sealing material for existing tunnel cracks, its preparation method, and its application. This invention constructs a stepped sealing mechanism of "penetration-expansion-curing-sealing" through the synergistic effect of composite multiphase materials. This material is not only environmentally friendly and has adjustable strength, but also has excellent erosion resistance, enabling long-term sealing of cracks.

[0006] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides an adaptive sealing material for existing cracks in tunnels, comprising component A and component B; wherein the mass ratio of component A to component B is (5~8):1; Component A, by mass parts, comprises: 30-40 parts of modified epoxy emulsion, 15-25 parts of functional monomer, 8-15 parts of nanocomposite filler, 5-10 parts of swelling promoter, 1-3 parts of dispersant, and 10-20 parts of deionized water. Component B, by weight, comprises: 40-60 parts of latent curing agent, 5-10 parts of nano-catalyst, 20-30 parts of slow-release carrier, and 1-2 parts of defoamer.

[0007] Preferably, the modified epoxy emulsion is prepared by grafting epoxy resin with carboxyl-terminated butadiene-acrylonitrile rubber.

[0008] Preferably, the functional monomers include hydroxypropyl methacrylate and N-vinylpyrrolidone, and the mass ratio of hydroxypropyl methacrylate to N-vinylpyrrolidone is (3~5):1.

[0009] Preferably, the nanocomposite filler comprises nano-silica and montmorillonite modified with silane coupling agent KH-560, and the mass ratio of the nano-silica to the montmorillonite modified with silane coupling agent KH-560 is 1:(2~3). Preferably, the swelling promoter is polyacrylic acid grafted chitosan.

[0010] Preferably, the latent curing agent is a microencapsulated amine curing agent; the core of the microencapsulated amine curing agent is an amine curing agent, and the encapsulation material of the microencapsulated amine curing agent is polyurea-formaldehyde resin.

[0011] Preferably, the nanocatalyst is a supported nano zinc oxide; the supported nano zinc oxide includes activated carbon and nano zinc oxide supported on the activated carbon.

[0012] Preferably, the slow-release carrier is bentonite; the dispersant is sodium polycarboxylate; and the defoamer is an organosilicone defoamer.

[0013] Secondly, the present invention provides a method for preparing an adaptive sealing material for existing cracks in tunnels, comprising the following steps: Preparation of component A: Weigh 15 to 25 parts of functional monomer, 1 to 3 parts of dispersant and 10 to 20 parts of deionized water, mix them and stir until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 30 to 40 parts of modified epoxy emulsion were added dropwise under stirring. Stirring was continued to form a homogeneous emulsion. 8 to 15 parts of nanocomposite filler and 5 to 10 parts of swelling promoter were added sequentially to the homogeneous emulsion. The mixture was heated and stirred to react. After cooling to room temperature, component A was obtained. Preparation of component B: Under a nitrogen atmosphere, 40 to 60 parts of latent curing agent, 5 to 10 parts of nano-catalyst and 20 to 30 parts of slow-release carrier are mixed, stirred and ultrasonically dispersed to obtain a second mixed solution. Add 1 to 2 parts of defoamer to the second mixed solution and continue stirring until there are no obvious bubbles to obtain component B; The components A and B are mixed evenly at a mass ratio of (5~8):1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0014] Thirdly, this invention provides an application of an adaptive sealing material for existing tunnel cracks in the repair and waterproofing of cracks in tunnels and underground engineering.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs an adaptive plugging system with a step-like response characteristic through the synergistic effect of components A and B. Specifically, component A, using a modified epoxy emulsion as the film-forming substrate, endows the cured material with excellent flexibility and interfacial compatibility with the crack wall, effectively avoiding secondary cracking caused by the excessive brittleness of traditional epoxy materials; the introduction of functional monomers provides sufficient crosslinking sites for the system and enhances the stability of the material in aqueous media, ensuring that the expansion process proceeds in an orderly manner within a controllable range; the nanocomposite filler forms a strong bond with the matrix through surface chemical modification, improving the overall mechanical strength while refining the microstructure using the nano-size effect, significantly enhancing the material's impermeability; the expansion promoter utilizes the synergistic swelling effect of carboxyl and amino groups in the molecular chain upon contact with water to achieve a gradual increase in material volume with an adjustable expansion rate, avoiding secondary damage to cracks caused by excessively rapid expansion. The latent curing agent in component B employs a microencapsulated structure, delaying the curing reaction after the material has fully penetrated deep into the crack. Combined with the layered physical adsorption of the slow-release carrier, this achieves dual regulation of curing time. The nano-catalyst further densifies the cured product, and the addition of an antifoaming agent ensures the uniformity and defect-free filling of the mixed slurry. This invention solves the technical problems of traditional sealing materials, such as difficulty in penetrating fine cracks, susceptibility to erosion under high-pressure water flow, and insufficient adhesion strength to crack walls. It achieves adaptive sealing and long-lasting water-stopping effects for cracks of different widths and moisture contents. Detailed Implementation

[0016] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0017] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0018] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0019] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0020] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0021] The first objective of this invention is to provide an adaptive sealing material for existing cracks in tunnels, comprising component A and component B; wherein the mass ratio of component A to component B is (5~8):1; Component A, by mass parts, comprises: 30-40 parts of modified epoxy emulsion, 15-25 parts of functional monomer, 8-15 parts of nanocomposite filler, 5-10 parts of swelling promoter, 1-3 parts of dispersant, and 10-20 parts of deionized water. Component B, by weight, comprises: 40-60 parts of latent curing agent, 5-10 parts of nano-catalyst, 20-30 parts of slow-release carrier, and 1-2 parts of defoamer.

[0022] For example, the modified epoxy emulsion is made by grafting epoxy resin with carboxyl-terminated nitrile butadiene rubber. It utilizes the active carboxyl groups at the ends of the nitrile butadiene rubber molecular chains to chemically react with the epoxy and hydroxyl groups on the epoxy resin molecular chains, thereby introducing flexible rubber segments into the rigid epoxy resin skeleton in the form of chemical bonds, forming a graft copolymer that combines the elasticity of rubber and the adhesiveness of epoxy resin. Furthermore, the epoxy value of the modified epoxy emulsion is controlled at 0.4~0.6 eq / 100g, ensuring that the modified epoxy resin retains sufficient active epoxy groups to participate in subsequent curing and crosslinking reactions, ensuring a strong chemical bond between the material and the crack wall. The introduction of flexible segments significantly reduces the brittleness of the cured epoxy, allowing it to absorb energy through the microscopic deformation of the rubber phase when subjected to minor deformations caused by geological changes or vehicle loads in the tunnel structure, effectively preventing the formation of secondary leakage channels due to brittle cracking of the cured material.

[0023] Furthermore, the method for preparing the modified epoxy emulsion is as follows: Using E-51 type epoxy resin with an epoxy value of 0.48~0.54 eq / 100g as the base material, it is added to a reaction vessel equipped with a mechanical stirrer and thermometer. Stirring is started and the temperature is heated to 80~85℃. After the system temperature stabilizes, carboxyl-terminated nitrile rubber is slowly added to the system. The molecular weight of the carboxyl-terminated nitrile rubber is controlled at 3000~5000, the carboxyl content is 1.8~2.2 mmol / g, and the amount added accounts for 12% of the mass of epoxy resin. After the addition is completed, the temperature is continued to rise to 88~90℃ and maintained at this temperature for 2.5h. During the reaction, the epoxy value is sampled and tested every 30min until the epoxy value drops to the target range of 0.4~0.6 eq / 100g, at which point the reaction is terminated. Heating is stopped and the material is allowed to cool naturally to room temperature to obtain a brownish-yellow viscous modified epoxy emulsion. The product needs to be sealed and stored in the dark for later use.

[0024] For example, the functional monomers include hydroxypropyl methacrylate (purity ≥98%) and N-vinylpyrrolidone (purity ≥99%), and the mass ratio of hydroxypropyl methacrylate to N-vinylpyrrolidone is (3~5):1. Hydroxypropyl methacrylate provides good crosslinking sites, while N-vinylpyrrolidone enhances the stability of the material in aqueous media and ensures the controllability of the expansion process.

[0025] Specifically, hydroxypropyl methacrylate contains both vinyl double bonds and active hydroxyl groups in its molecular structure. The vinyl double bonds can participate in free radical polymerization or undergo ring-opening reactions with epoxy groups during the curing process, providing sufficient cross-linking sites for the material system to form a three-dimensional network structure. The hydroxyl groups can chemically bond or hydrogen bond with the residual epoxy groups in the modified epoxy emulsion and the hydroxyl groups on the crack walls, thereby significantly enhancing the interfacial adhesion. N-vinylpyrrolidone, due to the presence of a highly polar lactam structure in its molecule, has excellent water solubility and water absorption and retention capabilities. When the material is injected into water-containing cracks, this component can form hydrogen bond complexes with water molecules, which on the one hand delays the dilution and erosion of the uncured material by water, and on the other hand induces the orderly distribution of water molecules during the formation of the curing network, avoiding microscopic defects caused by local water accumulation, thereby enhancing the structural stability of the cured product in the aqueous medium.

[0026] For example, the nanocomposite filler includes nano-silica (particle size 20~30nm, specific surface area 150~200m²). 2 The nano-silica ( / g) and montmorillonite modified with silane coupling agent KH-560 (particle size ≤2μm, and the amount of modifier is 5% of the mass of montmorillonite), and the mass ratio of the nano-silica to the montmorillonite modified with silane coupling agent KH-560 is 1:(2~3). The synergistic effect of the two not only avoids the defects of easy agglomeration and uneven dispersion of single nanofillers, but also forms a denser and more uniform micro-network structure inside the material through the dual mechanism of chemical bonding and physical filling. Thus, while improving the overall mechanical strength, it significantly enhances the material's water penetration resistance and long-term durability.

[0027] Specifically, nano-silica, due to its small particle size, large specific surface area, and rich silanol groups on the surface, can effectively fill the molecular-level voids in the polymer network. Through the nano-size effect, it refines the microstructure of the cured product. At the same time, its surface hydroxyl groups can react chemically with the epoxy and hydroxyl groups in the matrix to form chemical bonds, thereby significantly improving the material's density and mechanical strength. Montmorillonite, as a natural nano-mineral with a layered silicate structure, after being modified with the silane coupling agent KH-560, has increased interlayer spacing and its interlayer surface changes from hydrophilic to lipophilic. After the alkoxy group at one end of the coupling agent molecule hydrolyzes, it condenses with the hydroxyl groups on the surface of the montmorillonite layer to form covalent bonds. The epoxy or amino functional groups at the other end can participate in the curing reaction of the matrix resin, thereby allowing montmorillonite to be uniformly dispersed in the polymer matrix in the form of exfoliation or intercalation, forming a physical barrier structure. This effectively extends the penetration path of water and corrosive media, significantly improving the material's impermeability.

[0028] For example, the swelling promoter is polyacrylic acid grafted with chitosan, and the grafting rate is not less than 30%. The amino groups abundant in the chitosan molecular chain protonate upon contact with water, becoming positively charged, resulting in molecular chain extension and initial water absorption and swelling. The grafted polyacrylic acid segments contain a large number of carboxyl groups, which ionize under neutral and alkaline conditions, generating a negative charge. This further enhances the electrostatic repulsion within and between the molecular chains. Simultaneously, the hydrogen bonds formed between the carboxyl groups and water molecules significantly improve hydration capacity. The synergistic effect of these two factors at the molecular level enables the copolymer to produce a significant volume expansion effect upon contact with water. Furthermore, the expansion rate can be precisely controlled by adjusting the grafting rate, avoiding excessive compressive stress on the crack wall caused by excessively rapid instantaneous volume expansion, thus preventing secondary damage. Ultimately, this achieves a sealing effect of gradual filling and moderate compaction of the material within the crack.

[0029] For example, the latent curing agent is a microencapsulated amine curing agent; the core of the microencapsulated amine curing agent is an amine curing agent (such as ethylenediamine), the encapsulation material of the microencapsulated amine curing agent is polyurea formaldehyde resin, and the average particle size of the microcapsules is controlled within the range of 5~15μm. This invention isolates the highly reactive amine curing agent from the external environment through the physical barrier effect of the capsule material, maintaining the curing agent's chemical inertness during material storage and delivery before injection into the crack, thus preventing premature contact with the epoxy groups in component A and subsequent pre-curing reaction. When component B containing microcapsules is mixed with component A and injected into the crack, water in the mixed slurry gradually permeates into the microcapsules. Although the polyurea-formaldehyde resin capsule material is insoluble in water, it has a certain degree of hydrophilicity and permeability. Water molecules permeate through the capsule wall, dissolving the amine curing agent in the capsule core and forming a locally high-concentration solution inside the capsule. As the permeation process continues, the concentration difference between the inside and outside of the capsule drives the dissolved curing agent molecules to slowly diffuse through the capsule wall into the epoxy resin system outside the capsule, thereby achieving delayed release and gradual supply of the curing agent.

[0030] For example, the nanocatalyst is a supported nano-zinc oxide; the supported nano-zinc oxide includes activated carbon and nano-zinc oxide supported on the activated carbon, and the loading of nano-zinc oxide is in the range of 10% to 15%. The activated carbon support itself has a certain adsorption and enrichment effect on amine curing agents and epoxy resins, which can attract reactant molecules to form local high-concentration micro-regions around the nano-zinc oxide, thereby significantly improving the initiation efficiency and reaction rate of the curing reaction; during the curing process, the nano-zinc oxide can also act as a heterogeneous nucleation site, inducing the orderly arrangement and growth of the cured products around it, refining the microstructure of the cured products through the physical template effect of nanoscale, transforming the originally potentially coarse cross-linked network structure into a more uniform and fine micromorphology.

[0031] For example, the sustained-release carrier is bentonite, whose crystal structure consists of two layers of silicon-oxygen tetrahedra sandwiching a layer of aluminum-oxygen octahedra, forming a typical 2:1 layered structure. When bentonite is introduced into component B as a sustained-release carrier, its layered structure is used to perform secondary adsorption and delayed diffusion of the amine curing agent and nanocatalyst released from the microcapsules. That is, when the microcapsules begin to release the curing agent under the action of moisture, the released curing agent molecules and catalyst particles are immediately adsorbed or intercalated by the surrounding bentonite sheets. Due to the confinement effect between the bentonite layers and the physical barrier effect of the sheets on the diffusion path, the actual contact between the curing agent and the catalyst and its reaction with the epoxy groups in component A are further delayed, thereby forming a dual regulation on the time scale with the capsule wall permeation mechanism of the microcapsules. In addition, the slow-release effect of bentonite is adjustable. Different crack lengths require different penetration times for the material. Short cracks need to solidify quickly to prevent material loss, while long cracks require a longer penetration time to ensure deep filling. By adjusting the amount of bentonite and its ratio with microcapsules, the sealing needs of cracks of different lengths can be met.

[0032] For example, the dispersant is sodium polycarboxylate (molecular weight 20,000~30,000), which is a highly efficient anionic surfactant in aqueous systems. It plays a dispersing and stabilizing role by virtue of its comb-type copolymer molecular structure. The sodium carboxylate anchoring groups in the molecular chain are tightly adsorbed onto the surface of the nanocomposite filler and modified epoxy emulsion particles through electrostatic interaction, while the polyether side chains extending into the aqueous phase form a three-dimensional barrier through steric hindrance. The electrostatic repulsion and steric hindrance generated by the synergy of the two can effectively overcome the van der Waals attraction between particles, prevent the agglomeration and sedimentation of fine components such as nano silica and modified montmorillonite, and keep the entire component A system in a uniform and stable suspension state during storage and grouting.

[0033] For example, the defoamer is an organosilicon defoamer (30% effective ingredient content). With its extremely low surface tension and extremely low solubility in the aqueous phase, it can quickly spread at the gas-liquid interface during the mixing of component B and component A and the grouting process, destroying the elasticity of the bubble film wall and promoting the merging and rupture of bubbles, thereby efficiently removing the micro bubbles introduced by the dispersant, nanofiller and stirring process.

[0034] The second objective of this invention is to provide a method for preparing an adaptive sealing material for existing cracks in tunnels, comprising the following steps: Preparation of component A: Weigh 15-25 parts of functional monomer, 1-3 parts of dispersant and 10-20 parts of deionized water, mix them and stir at a stirring rate of 600-800 r / min for 10-15 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 30 to 40 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 8 to 12 mL / min under stirring conditions of 350 to 500 r / min. Stirring was continued for 15 to 20 min to form a homogeneous emulsion. Add 8 to 15 parts of nanocomposite filler and 5 to 10 parts of swelling promoter to the homogeneous emulsion in sequence. Then heat the system to 50 to 60°C and stir at a constant temperature of 400 to 600 r / min for 30 to 40 min to allow the components to react and disperse fully. After the reaction is completed, cool naturally to room temperature to obtain component A. Preparation of component B: Under nitrogen atmosphere protection, 40-60 parts of latent curing agent, 5-10 parts of nano catalyst and 20-30 parts of slow-release carrier are mixed and ultrasonic dispersion is started simultaneously under stirring at 200-300 r / min, ultrasonic power is controlled at 300-500W, dispersion treatment is performed for 10-15 min to obtain the second mixed solution. Add 1 to 2 parts of defoamer to the second mixed solution and continue stirring for 5 to 10 minutes until no obvious bubbles are present to obtain component B. The components A and B are mixed evenly at a mass ratio of (5~8):1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0035] In this invention, component A is prepared using a combination of controlled-rate dripping and gradient stirring, effectively preventing phase separation between the modified epoxy emulsion and the functional monomers. The heating reaction promotes the chemical bonding between the nanofiller and the matrix. Component B is dispersed under nitrogen protection combined with ultrasonic assistance, ensuring the integrity of the microencapsulated curing agent and the nanoscale uniform distribution of each powder component. The preparation process of this invention is simple, easy to operate, and highly repeatable. The resulting material can quickly initiate a step-by-step sealing mechanism of penetration-expansion-curing during use, fully leveraging the synergistic effect between the components and significantly improving the adaptive sealing effect and long-term stability of existing tunnel cracks.

[0036] The third objective of this invention is to provide an adaptive sealing material for existing tunnel cracks in the repair and waterproofing of cracks in tunnels and underground engineering. This invention can fully utilize the material's stepped response mechanism to cope with the complex and variable leakage environment of underground engineering. When the material is injected into existing cracks in the tunnel lining, its low initial viscosity and excellent wetting properties allow it to preferentially penetrate into the deep areas of micro-cracks. Subsequently, the expansion promoter triggers controllable volume growth under water conditions, forming an initial compression filling of the crack. At the same time, the microencapsulated curing agent gradually releases active components under the dual regulation of moisture and slow-release carrier, initiating a curing reaction that transforms the expanded filler into a solidified layer with high bonding strength and structural density. This process enables the material to adapt to changes in crack width, moisture content differences, and water pressure fluctuations, without the need for frequent adjustments to construction parameters for different working conditions. Compared to traditional sealing materials that rely solely on a single expansion or curing mechanism and struggle to balance penetration depth and sealing density, this invention's material, when applied in tunnel engineering, effectively addresses the rapid loss under high-pressure water inrush conditions. Simultaneously, it maintains stable volume and strength in alternating wet and dry environments, achieving a strong interface bond through excellent affinity with damp substrates, preventing repeated leakage due to secondary cracking. Applying this material to the treatment of tunnel construction joints, expansion joints, and irregular network cracks significantly improves the integrity and durability of the waterproofing layer, extends the maintenance cycle of the tunnel structure, and reduces leakage control costs during operation. It is particularly suitable for underground engineering environments with complex geological conditions, significant water pressure variations, and frequent vibration loads.

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0039] Example Example 1: Sealing of 1-2mm wide damp cracks in railway tunnels Material preparation: Weigh 18 parts of hydroxypropyl methacrylate, 4.5 parts of N-vinylpyrrolidone, 1.5 parts of sodium polycarboxylate and 14 parts of deionized water, mix them and stir at a stirring rate of 600 r / min for 10 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 32 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 8 mL / min under stirring at 350 r / min. Stirring was continued for 15 min to form a homogeneous emulsion. Five parts of nano-silica, 10 parts of montmorillonite modified with silane coupling agent KH-560, and 6 parts of polyacrylic acid grafted chitosan were added sequentially to the homogeneous emulsion. The system was then heated to 50°C and stirred at a constant temperature of 400 r / min for 30 min to allow the components to react and disperse fully. After the reaction was completed, the system was naturally cooled to room temperature to obtain component A. Under nitrogen atmosphere protection, 45 parts of microencapsulated amine curing agent (core is ethylenediamine, capsule material thickness is 1~2μm, average particle size is 8μm), 6 parts of supported nano zinc oxide and 28 parts of bentonite were mixed and ultrasonic dispersion was started simultaneously under stirring at 200r / min, ultrasonic power was controlled at 300W, dispersion treatment was performed for 10min to obtain the second mixed solution. Add 1 part of organosilicon defoamer to the second mixed solution and continue stirring for 5 minutes until no obvious bubbles are present to obtain component B; The components A and B are mixed evenly at a mass ratio of 8:1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0040] Construction Process: The crack was found to be a linear seepage line with a width of 1.2mm. During base treatment, the surface was cleaned with a wire brush, rinsed with a high-pressure water gun, and dried with a hot air blower (moisture content 7%). Grouting nozzles were arranged at 25cm intervals and sealed with quick-drying sealant. Grouting parameters were set with an initial pressure of 1.8MPa and a flow rate of 60mL / min, and the process was carried out in three stages: during the seepage stage, the pressure was 1.1MPa for 10 minutes; during the expansion stage, the pressure was increased to 1.8MPa until grout appeared from adjacent nozzles; and during the pressure replenishment stage, the pressure was increased to 2.0MPa for 5 minutes to consolidate. The surface was allowed to cure for 5 hours at an ambient temperature of 20℃. After removing the grouting nozzles, the surface was repaired with polymer mortar.

[0041] Test results: No leakage was observed during the 24-hour water pressure test (0.3MPa). Core sampling showed a bonding strength of 3.8MPa and a surface flatness error of 2mm, meeting the operational requirements of railway tunnels.

[0042] Example 2: Repair of 3-5mm wide cracks in highway tunnels with water inflow Material preparation: Weigh 20 parts of hydroxypropyl methacrylate, 5 parts of N-vinylpyrrolidone, 2.5 parts of sodium polycarboxylate and 17 parts of deionized water, mix them and stir at a stirring rate of 700 r / min for 12 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 38 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 10 mL / min under stirring conditions of 400 r / min. Stirring was continued for 18 min to form a homogeneous emulsion. Add 3 parts of nano-silica, 9 parts of montmorillonite modified with silane coupling agent KH-560, and 9 parts of polyacrylic acid grafted chitosan to the homogeneous emulsion in sequence. Then heat the system to 55°C and stir at a constant temperature of 500 r / min for 35 min to allow the components to react and disperse fully. After the reaction is completed, cool naturally to room temperature to obtain component A. Under nitrogen atmosphere protection, 55 parts of microencapsulated amine curing agent (core is ethylenediamine, capsule material thickness is 1~2μm, average particle size is 5μm), 9 parts of supported nano zinc oxide and 22 parts of bentonite were mixed and ultrasonic dispersion was started simultaneously under stirring at 250r / min, ultrasonic power was controlled at 400W, dispersion treatment was performed for 12min to obtain the second mixed solution. Add 1.8 parts of organosilicon defoamer to the second mixed solution and continue stirring for 8 minutes until no obvious bubbles are present to obtain component B; The components A and B are mixed evenly at a mass ratio of 5:1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0043] Construction Process: For a 4mm wide water-seeping crack, a 6mm deep V-shaped groove was first chiseled along the crack. After temporary water control with quick-setting cement, grouting nozzles (spaced 15cm apart) were installed. Component A was preheated in a 50℃ water bath, and component B was mixed in proportion using a dual-liquid grouting pump after passing through an 80-mesh sieve. The initial pressure was set at 5MPa, and the flow rate at 90mL / min. A segmented grouting method was adopted (each segment 1.2m): the pressure was 3MPa during the infiltration period, gradually increasing to 5MPa during the expansion period, and reaching 5.5MPa during the pressure replenishment period. Curing was carried out at an ambient temperature of 15℃ for 8 hours, with electric blankets used for insulation during low-temperature periods.

[0044] Test results: No leakage was observed during the 30-minute impermeability test, the chloride ion penetration depth was 3.2 mm, and the bond strength was 4.2 MPa, meeting the durability requirements under vibration loads in highway tunnels.

[0045] Example 3: Sealing of dry microcracks in subway tunnels with a width of <0.5mm Material preparation: Weigh 20 parts of hydroxypropyl methacrylate, 5 parts of N-vinylpyrrolidone, 2 parts of sodium polycarboxylate and 14 parts of deionized water, mix them and stir at a stirring rate of 800 r / min for 15 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 35 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 12 mL / min under stirring conditions of 500 r / min. Stirring was continued for 20 min to form a homogeneous emulsion. Add 3 parts of nano-silica, 9 parts of montmorillonite modified with silane coupling agent KH-560, and 7 parts of polyacrylic acid grafted chitosan to the homogeneous emulsion in sequence. Then heat the system to 60°C and stir at a constant temperature of 600 r / min for 40 min to allow the components to react and disperse fully. After the reaction is completed, cool naturally to room temperature to obtain component A. Under a nitrogen atmosphere, 50 parts of microencapsulated amine curing agent (with ethylenediamine as the core, a capsule material thickness of 1-2 μm, and an average particle size of 15 μm), 7 parts of supported nano zinc oxide, and 25 parts of bentonite were mixed and ultrasonically dispersed simultaneously under stirring at 300 r / min with the ultrasonic power controlled at 500 W for 15 min to obtain a second mixed solution. Add 1.5 parts of organosilicon defoamer to the second mixed solution and continue stirring for 10 minutes until no obvious bubbles are present to obtain component B; The components A and B are mixed evenly at a mass ratio of 7:1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0046] Construction process: The crack width was 0.3mm and the surface was dry. After grinding the base layer, it was purged with compressed air. The grouting nozzles were spaced 35cm apart. Grouting began 3 hours after the sealant had cured. The initial pressure was 1.5MPa, the flow rate was 50mL / min, the pressure was maintained at 0.9MPa during the penetration period, increased to 1.5MPa during the expansion period, and then pressurized to 1.6MPa. The surface was allowed to cure at 25℃ for 4 hours. After removing the grouting nozzles, the surface was directly sanded.

[0047] Test results: No obvious repair marks on the surface, flatness error of 1mm, core bonding strength of 3.6MPa, meeting the standards for refined repair of subway tunnels.

[0048] Example 4 Material preparation: Weigh 12 parts of hydroxypropyl methacrylate, 4 parts of N-vinylpyrrolidone, 1 part of sodium polycarboxylate and 10 parts of deionized water, mix them and stir at a stirring rate of 650 r / min for 11 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 30 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 10 mL / min under stirring at 450 r / min. Stirring was continued for 17 min to form a homogeneous emulsion. Two parts of nano-silica, six parts of montmorillonite modified with silane coupling agent KH-560, and five parts of polyacrylic acid-grafted chitosan were added sequentially to the homogeneous emulsion. The system was then heated to 50°C and stirred at a constant temperature of 450 r / min for 35 min to allow the components to react and disperse fully. After the reaction was completed, the system was naturally cooled to room temperature to obtain component A. Under nitrogen atmosphere protection, 40 parts of microencapsulated amine curing agent (the core is ethylenediamine, the encapsulation material thickness is 1~2μm, and the average particle size is 10μm), 5 parts of supported nano zinc oxide and 20 parts of bentonite were mixed and ultrasonic dispersion was started simultaneously under stirring at 200r / min, the ultrasonic power was controlled at 450W, and the dispersion treatment was carried out for 15min to obtain the second mixed solution. Add 1 part of organosilicon defoamer to the second mixed solution and continue stirring for 5 minutes until no obvious bubbles are present to obtain component B; The components A and B are mixed evenly at a mass ratio of 5:1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0049] Example 5 Material preparation: Weigh 20 parts of hydroxypropyl methacrylate, 4 parts of N-vinylpyrrolidone, 2 parts of sodium polycarboxylate and 15 parts of deionized water, mix them and stir at a stirring rate of 750 r / min for 13 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 35 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 9 mL / min under stirring conditions of 400 r / min. Stirring was continued for 16 min to form a homogeneous emulsion. Add 3 parts of nano-silica, 7 parts of montmorillonite modified with silane coupling agent KH-560, and 8 parts of polyacrylic acid grafted chitosan to the homogeneous emulsion in sequence. Then heat the system to 52°C and stir at a constant temperature of 550 r / min for 35 min to allow the components to react and disperse fully. After the reaction is completed, cool naturally to room temperature to obtain component A. Under nitrogen atmosphere protection, 50 parts of microencapsulated amine curing agent (core is ethylenediamine, capsule material thickness is 1~2μm, average particle size is 12μm), 8 parts of supported nano zinc oxide and 25 parts of bentonite were mixed and ultrasonic dispersion was started simultaneously under stirring at 250r / min, ultrasonic power was controlled at 350W, dispersion treatment was performed for 12min to obtain the second mixed solution. Add 1.5 parts of organosilicon defoamer to the second mixed solution and continue stirring for 10 minutes until no obvious bubbles are present to obtain component B; The components A and B are mixed evenly at a mass ratio of 6:1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0050] Example 6 Material preparation: Weigh 12 parts of hydroxypropyl methacrylate, 3 parts of N-vinylpyrrolidone, 3 parts of sodium polycarboxylate and 20 parts of deionized water, mix them and stir at a stirring rate of 800 r / min for 14 min until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 40 parts of modified epoxy emulsion were slowly added dropwise at a dropping rate of 12 mL / min under stirring at 350 r / min. Stirring was continued for 20 min to form a homogeneous emulsion. Four parts of nano-silica, eight parts of montmorillonite modified with silane coupling agent KH-560, and ten parts of polyacrylic acid grafted chitosan were added sequentially to the homogeneous emulsion. The system was then heated to 60°C and stirred at a constant temperature of 600 r / min for 40 min to allow the components to react and disperse fully. After the reaction was completed, the system was naturally cooled to room temperature to obtain component A. Under nitrogen atmosphere protection, 60 parts of microencapsulated amine curing agent (core is ethylenediamine, capsule material thickness is 1~2μm, average particle size is 8μm), 10 parts of supported nano zinc oxide and 30 parts of bentonite were mixed and ultrasonic dispersion was started simultaneously under stirring at 300r / min, ultrasonic power was controlled at 500W, dispersion treatment was performed for 10min to obtain the second mixed solution; Add 2 parts of organosilicon defoamer to the second mixed solution and continue stirring for 10 minutes until no obvious bubbles are present to obtain component B; The components A and B are mixed evenly at a mass ratio of 8:1 to obtain the adaptive sealing material for existing cracks in the tunnel.

[0051] Example 7: Industrial production of adaptive sealing materials for existing tunnel cracks (1) Industrial production of modified epoxy emulsions Epoxy resin E-51 (epoxy value 0.48~0.54 eq / 100g) was selected as the base material and stored at 5m. 3 Before use, the stainless steel storage tank is filtered through a 5μm precision filter. The carboxyl-terminated nitrile butadiene rubber (CNBR, molecular weight 3000~5000, carboxyl content 1.8~2.2mmol / g) is crushed to a particle size ≤5mm and then fed into the metering silo via a screw conveyor.

[0052] Using 10m 3A stainless steel reactor (equipped with jacketed heating, anchor-type agitator, reflux condenser, and online epoxy value analyzer) was used to maintain a slight positive pressure of 0.02 MPa inside the reactor. 8000 kg of epoxy resin was added to the reactor, and the jacketed steam heating was turned on, with a heating rate controlled at 2℃ / min and a stirring rate of 300 r / min. When the temperature reached 80℃, 960 kg of CNBR (12% of the epoxy resin mass) was added through a metering screw, and the temperature was further increased to 88℃. The reaction was maintained at this temperature for 2.5 h, and the epoxy value was measured every 30 min using the online analyzer. The reaction was terminated when the epoxy value stabilized at 0.45~0.55 eq / 100g. The jacketed cooling water (25℃) was turned on to cool the mixture to below 40℃, and the emulsion was pumped to a 10 m³ emulsion storage tank (with agitator) using a gear pump (500 L / h) for later use, resulting in a brownish-yellow viscous modified epoxy emulsion.

[0053] (2) Industrial production of component A Raw material preparation: The functional monomers hydroxypropyl methacrylate (MHP) and N-vinylpyrrolidone (NVP) were stored separately at 2m³. 3 The cryogenic storage tank (5℃) is premixed in a static mixer at a mass ratio of 3:1 (MHP 1875kg, NVP 625kg, total 2500kg) before use; the nanocomposite filler is premixed in a twin-screw mixer (800r / min) at a mass ratio of 2:1 with KH-560 modified montmorillonite and nano silica for 30min (montmorillonite 800kg, silica 400kg, total 1200kg); the expansion accelerator (polyacrylic acid grafted chitosan, grafting rate 32%) is used after impurity removal by a 0.15mm vibrating screen; the dispersant is sodium polycarboxylate (molecular weight 20000~30000); deionized water is used.

[0054] Production steps: Using 20m 3 Multifunctional reactor (with bottom anchor paddle + top propeller paddle, jacket temperature control, online viscometer). Add 1500 kg of deionized water and 200 kg of dispersant to the reactor, and start stirring (400 r / min) for 10 min until completely dissolved. Pump in 3500 kg of the modified epoxy emulsion prepared in step (1) through a metering pump, and simultaneously pump in 2500 kg of premixed functional monomers. Adjust the stirring speed to 500 r / min and mix for 20 min. Add 1200 kg of nanocomposite filler and 700 kg of expansion promoter in sequence, close the reactor lid, heat the jacket to 55°C, increase the stirring speed to 600 r / min, and stir at a constant temperature for 35 min. Take a sample to test the viscosity, the target is 400~600 mPa·s. After passing the test, turn on the cooling water to cool down to 30°C, and pump it to 20 m³ / min through a screw pump. 3 The finished product container of component A (under nitrogen protection) yielded a grayish-white viscous component A.

[0055] (3) Industrial production of component B Raw material preparation: The latent curing agent (microencapsulated amine, core of which is ethylenediamine, encapsulation material is polyurea formaldehyde resin, average particle size 8μm) is pulverized to 5~15μm by an air jet mill and premixed with the slow-release carrier (sodium bentonite) at a mass ratio of 2:1 in a plow-type mixer for 1h (approximately 3333kg of curing agent and approximately 1667kg of bentonite, totaling 5000kg); the nano-catalyst (supported nano-zinc oxide / activated carbon, zinc oxide loading 12%) is vacuum dried (80℃, -0.08MPa) for 2h and then stored in a dry silo.

[0056] Production steps: using 10m 3 Plow-type mixer (with 5kW ultrasonic vibration device and nitrogen protection system). Add 5100kg of premixed curing agent-bentonite mixture (3400kg curing agent, 1700kg bentonite) to the mixer, and start nitrogen purging (flow rate 2m³ / h). 3 / h, 3min), ensuring oxygen content ≤0.5%. Add 800kg of nano-catalyst via vacuum feeder, turn on ultrasonic vibration (20kHz) and stirring (300r / min), disperse for 15min. Add 120kg of organosilicon defoamer, turn off ultrasonication, reduce stirring speed to 200r / min, mix for 10min. Sample and test particle size distribution (D50=8~12μm), after passing the test, feed into a 10m silane system via pneumatic conveying. 3 The finished product container of component B (moisture-proof design) yields a light gray powder of component B.

[0057] (4) Finished product blending and quality indicators A twin-screw dynamic mixer (2t / h capacity) was used to simultaneously feed components A and B at a 6:1 mass ratio via a metering pump (accuracy ±0.5%). The screw speed was 1500 r / min, the mixing time was 3 min, and the viscosity at the outlet was monitored online as 300~500 mPa·s. The mixed product was then automatically filled into 20kg polyethylene drums with PTFE inner walls, and a one-way exhaust valve was installed at the drum opening. Ten drums were randomly selected from each batch for testing. The performance indicators were: 30-minute expansion rate ≥150%, bonding strength ≥3.5 MPa, curing time at 25℃ 4~6 h, and storage stability for 6 months (5~30℃). The key control points of this production process included: epoxy value deviation of modified epoxy emulsion ≤±0.05eq / 100g, particle size ≥5μm ratio in component A ≤0.1%, oxygen content in the component B mixture ≤0.5%, and automatic calibration of the metering pump flow rate every 8 h.

[0058] Example 8: Construction method of adaptive sealing material for existing cracks in tunnels This embodiment provides a complete construction method for sealing and repairing existing tunnel cracks using the adaptive sealing material described in this invention. This method fully utilizes the "penetration-expansion-curing-sealing" characteristics of the material through a stepped grouting process, and is suitable for treating tunnel cracks with widths of 0.2~5mm, different leakage states, and complex geological conditions.

[0059] First, a crack width gauge is used to accurately survey the cracks, determine their width range, and mark their direction and branch distribution. A hollow hammer is used to tap the area within 10cm of the crack to determine if there is loose substrate or hollowness. The water leakage situation is recorded in detail, categorized as dripping, linear leakage, or jetting, and archived using digital imaging technology as a basis for construction. Equipment preparation includes a high-pressure grouting pump (working pressure 1.5~8MPa), a dedicated static mixer with a mixing ratio of 5~8:1, an electric drill (with a φ6mm drill bit), a wire brush, and an angle grinder. Auxiliary materials include copper grouting nozzles (φ8mm diameter), quick-drying epoxy resin sealant, transparent tape, and non-woven fabric. For material pretreatment, component A needs to be heated in a 50℃ water bath for 30 minutes and stirred evenly at 300r / min before use; component B needs to be filtered through an 80-mesh sieve after opening to remove any possible agglomerated particles; the ratio of component A to component B is determined according to the measured crack width. For wide cracks with a width ≥2mm, a 5:1 ratio is used to enhance the filling density, and for narrow cracks with a width <2mm, an 8:1 ratio is used to ensure sufficient penetration.

[0060] Use an angle grinder with a wire wheel to grind a 10cm area on both sides of the crack to thoroughly remove surface laitance, oil, and loose layers. Then, use a high-pressure water gun (2-3 MPa) to rinse the ground surface until a solid concrete base is exposed. Use a hot air blower at 60-80℃ to dry the surface, ensuring the base layer's moisture content is ≤8%. For cracks wider than 3mm, chisel out V-grooves 5-8mm deep and 60° at the crack's direction to increase material filling space. For areas where honeycomb structures may exist internally, drill holes at 30cm intervals to explore and mark potential hazard areas. Finally, use 0.5MPa compressed air to blow away dust from inside the crack, ensuring the leakage channels are unobstructed.

[0061] Arrange grouting nozzles along the crack direction, with horizontal crack spacing controlled at 30-40cm and vertical crack spacing controlled at 20-30cm. Grouting nozzles must be installed at crack intersections. For areas with severe leakage, reduce the spacing to 15cm and use a quincunx pattern. Drill holes at the marked points with an electric drill, with a drilling depth no less than the crack depth plus 2cm. Insert the grouting nozzles and ensure they are connected to the inside of the crack. For sealing, apply quick-drying epoxy sealant along the crack surface, 5cm wide and 2-3mm thick, covering the grouting nozzle base. For cracks with high leakage, temporarily seal with quick-setting cement first, and apply sealant after the surface dries. Cover the sealant with transparent tape for protection before it cures, and allow it to cure for at least 2 hours at 25℃.

[0062] Grouting parameters are set according to crack width: initial pressure of 1.5-2 MPa for 0.2-1 mm cracks, 2-4 MPa for 1-3 mm cracks, and 4-6 MPa for cracks larger than 3 mm. Grouting flow rate is controlled at 50-100 mL / min, with lower values ​​for narrow cracks and higher values ​​for wide cracks. A dual-liquid grouting pump is used for automatic mixing, and the A and B components are mixed via a static mixer. The stepped grouting process is implemented in three stages: the first stage is the penetration period, starting from the lowest grouting nozzle, the pressure is gradually increased to 60% of the set value and maintained for 10 minutes, allowing the material to fully penetrate deep into the crack; the second stage is the expansion period, the pressure is increased to the set value, and the grout output from adjacent nozzles is observed. When the solid content of the outflowing grout reaches 80% or more, the current grouting nozzle is closed and the process switches to the next one; the third stage is the pressure replenishment period, after all grouting nozzles are completed, returning to the first grouting nozzle for secondary pressure replenishment, increasing the pressure by 10% and maintaining it for 5 minutes. When encountering jet-like leakage, first use a quick-setting sealing agent to temporarily seal it, and then proceed with grouting after the water pressure decreases; when encountering internal penetration of cracks, use the segmented grouting method, with each segment controlled within 1.5m in length, and proceed sequentially; when encountering a sudden drop in grouting pressure, immediately stop grouting and check for any channel connections, and supplement grouting nozzles if necessary.

[0063] After grouting, allow it to stand for 4-6 hours (at 25℃), during which time the grouting system must not be disturbed. If the ambient temperature is below 10℃, use an electric heating blanket for heat preservation and extend the curing time to 12 hours. During the curing period, closely observe the surface for any new water seepage points, and promptly re-grout if any problems are found. After complete curing, unscrew the grouting nozzle with a wrench, and grind the remaining part smooth with an angle grinder. Trim the surface of the grouting area and smooth it with polymer mortar to ensure it is flush with the original structural surface. After curing for 72 hours, sand the surface with sandpaper to prepare for the subsequent decorative layer construction.

[0064] Visual inspection requires no water leakage or obvious grouting marks on the surface. The repaired area should be tightly bonded to the original structure, without cracks or hollow areas, and the surface flatness error should be ≤3mm. Performance testing includes: core drilling (50mm diameter) to observe the interface bonding, with a bonding strength ≥3.5MPa; a 0.3MPa water pressure test on the repaired area, with no leakage after 30 minutes; and a chloride ion penetration test to verify durability, with a penetration depth ≤5mm. Through the above standardized construction methods, the stepped adaptive sealing characteristics of the material of this invention can be fully utilized to achieve a long-term water-stopping effect on existing tunnel cracks, making it suitable for crack repair projects under various alternating wet and dry conditions, vibration loads, and complex geological conditions.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-adaptive sealing material for existing cracks in tunnels, characterized in that, It includes component A and component B; the mass ratio of component A to component B is (5~8):1; Component A, by mass parts, comprises: 30-40 parts of modified epoxy emulsion, 15-25 parts of functional monomer, 8-15 parts of nanocomposite filler, 5-10 parts of swelling promoter, 1-3 parts of dispersant, and 10-20 parts of deionized water. Component B, by weight, comprises: 40-60 parts of latent curing agent, 5-10 parts of nano-catalyst, 20-30 parts of slow-release carrier, and 1-2 parts of defoamer.

2. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The modified epoxy emulsion is prepared by grafting epoxy resin with carboxyl-terminated butadiene-acrylonitrile rubber.

3. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The functional monomers include hydroxypropyl methacrylate and N-vinylpyrrolidone, and the mass ratio of hydroxypropyl methacrylate to N-vinylpyrrolidone is (3~5):

1.

4. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The nanocomposite filler comprises nano-silica and montmorillonite modified with silane coupling agent KH-560, and the mass ratio of nano-silica to montmorillonite modified with silane coupling agent KH-560 is 1:(2~3).

5. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The swelling promoter is polyacrylic acid grafted chitosan.

6. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The latent curing agent is a microencapsulated amine curing agent; the core of the microencapsulated amine curing agent is an amine curing agent, and the encapsulation material of the microencapsulated amine curing agent is polyurea-formaldehyde resin.

7. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The nanocatalyst is a supported nano zinc oxide; the supported nano zinc oxide includes activated carbon and nano zinc oxide supported on the activated carbon.

8. The self-adaptive sealing material for existing cracks in tunnels according to claim 1, characterized in that, The sustained-release carrier is bentonite; the dispersant is sodium polycarboxylate; and the defoamer is an organosilicon defoamer.

9. A method for preparing an adaptive sealing material for existing cracks in tunnels according to any one of claims 1 to 8, characterized in that, Includes the following steps: Preparation of component A: Weigh 15 to 25 parts of functional monomer, 1 to 3 parts of dispersant and 10 to 20 parts of deionized water, mix them and stir until completely dissolved to obtain the first mixed solution; The first mixed solution was placed in a reaction vessel, and 30 to 40 parts of modified epoxy emulsion were added dropwise under stirring. Stirring was continued to form a homogeneous emulsion. 8 to 15 parts of nanocomposite filler and 5 to 10 parts of swelling promoter were added sequentially to the homogeneous emulsion. The mixture was heated and stirred to react. After cooling to room temperature, component A was obtained. Preparation of component B: Under a nitrogen atmosphere, 40 to 60 parts of latent curing agent, 5 to 10 parts of nano-catalyst and 20 to 30 parts of slow-release carrier are mixed, stirred and ultrasonically dispersed to obtain a second mixed solution. Add 1 to 2 parts of defoamer to the second mixed solution and continue stirring until there are no obvious bubbles to obtain component B; The components A and B are mixed evenly at a mass ratio of (5~8):1 to obtain the adaptive sealing material for existing cracks in the tunnel.

10. The application of an adaptive sealing material for existing tunnel cracks according to any one of claims 1 to 8 in the repair and waterproofing of cracks in tunnels and underground engineering.