Nano aramid crystal glue modified polymer and tunnel anchoring and shotcreting support system

Abstract

The invention relates to the technical field of building materials, in particular to a nano aramid crystal gel modified polymer and a tunnel anchoring and shotcreting support system, and the polymer comprises the following components in percentage by mass: 3.0-8.5% of pretreated nano aramid fiber; 0.5%-2.5% of a functional carbon nano tube; 0.5 to 2.5 percent of silk fibroin nanofiber; 4.0 to 10.0% of a nano metal oxide / SiO2 mixed dispersion liquid; 65.0% to 85.0% of a polymer matrix; 0.8 to 1.8% of a bio-based plasticizer; 0.5%-6.0% of an intelligent self-repairing microcapsule; and 0.1 to 0.5 percent of an amphiphilic block copolymer dispersing agent. By introducing various nano materials and functional additives, the mechanical property, durability and self-repairing capacity of the sprayed concrete are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly to a nano-aramid crystal glue modified polymer and a tunnel anchor shotcrete support system. Background Art

[0002] In tunnel engineering construction, anchor shotcrete support is a commonly used support method. The traditional shotcrete support system has problems such as insufficient strength, poor durability, and weak crack resistance. Especially in complex geological environments and harsh construction conditions, phenomena such as cracking and spalling are likely to occur, affecting the safety and service life of the tunnel. Therefore, developing a high-performance concrete additive to improve the mechanical properties and durability of shotcrete has important practical significance.

[0003] However, there are many technical bottlenecks in the actual application of traditional shotcrete, which limit its further development and application. The main problems are as follows: After the construction of shotcrete is completed, it is necessary to reach a certain strength as soon as possible to play the support role. Especially in tunnel and slope projects, insufficient early strength may lead to increased deformation of the surrounding rock or matrix, and even cause safety accidents. Due to the limited hydration reaction rate of the cementitious material in traditional shotcrete, the early strength development is slow, and the 3-day compressive strength usually only reaches 50 - 60% of the design strength, resulting in a lag in the bearing capacity of the support structure and making it difficult to meet the requirements of rapid construction and immediate support.

[0004] Shotcrete is affected by factors such as matrix deformation and external force impact during the construction process and is prone to cracking. The toughness of traditional shotcrete is poor and the crack resistance is insufficient. In the 50 - 300 μm microcracks that are likely to occur in the concrete structure during the construction period, these cracks are difficult to repair autonomously, which will not only affect the integrity of the structure but also may cause problems such as leakage and steel bar corrosion, reducing the durability of the project.

[0005] The conventional early-strength agents (such as calcium chloride) used in shotcrete will introduce corrosive chloride ions, leading to steel bar corrosion and structural deterioration, and more likely reducing the durability of the project. It can be seen that traditional shotcrete is difficult to meet the requirements of modern projects for high performance, rapid construction, and high durability of shotcrete. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a nano-aramid crystal glue modified polymer and a tunnel anchor shotcrete support system. By introducing a variety of nano materials and functional additives, the mechanical properties, durability, and self-repair ability of shotcrete are significantly improved.

[0007] According to the first aspect of the present invention, a nano-aramid crystal glue modified polymer is provided, which includes the following components by mass percentage: Pre-treated nano aramid fiber: 3.0 - 8.5%; Functionalized carbon nanotubes (f-CNTs): 0.5 - 2.5%; Silk fibroin nanofibers (CNF): 0.5 - 2.5%; Nano metal oxide / SiO2 mixed dispersion: 4.0 - 10.0%; Polymer matrix: 65.0 - 85.0%; Bio-based plasticizer: 0.8 - 1.8%; Intelligent self-healing microcapsules: 0.5 - 6.0%; Amphiphilic block copolymer dispersant: 0.1 - 0.5%.

[0008] According to an embodiment of the present invention, the diameter of the pre-treated nano aramid fiber is 50 - 80 nm, the aspect ratio is 2000 - 5000, and it is secondarily modified with plasma grafted carboxyl (-COOH) and silane coupling agent KH-550, and the grafting rate is 1.2 - 3.5 mol%. This pre-treatment method can significantly improve the interfacial compatibility between the nano aramid fiber and the polymer matrix and enhance the mechanical properties of the composite material.

[0009] According to an embodiment of the present invention, the functionalized carbon nanotubes (f-CNTs) are multi-walled carbon nanotubes with an outer diameter of 8 - 15 nm, a length of 10 - 30 μm, and the surface grafted polyethylene glycol (PEG) has a molecular weight of 2000 - 5000 and a grafting density of 0.8 - 1.6 per nm 2 . The grafting of polyethylene glycol can improve the dispersibility of carbon nanotubes and endow them with good flexibility to avoid agglomeration in the polymer matrix.

[0010] According to an embodiment of the present invention, the silk fibroin nanofibers (CNF) are TEMPO-oxidized silk fibroin nanofibers with a diameter of 5 - 20 nm, a length of 1 - 3 μm, and a carboxyl content of 0.8 - 1.5 mmol / g. Silk fibroin nanofibers have excellent mechanical properties and biocompatibility, and can significantly improve the toughness and impact resistance of the composite material.

[0011] According to an embodiment of the present invention, in the nano metal oxide / SiO2 mixed dispersion, the mass ratio of TiO2@SiO2 core-shell structured nanoparticles to ordinary nano SiO2 is 1.5:1 - 2.5:1, where the TiO2 inner core particle size is 10 - 20 nm and the SiO2 shell layer thickness is 2 - 5 nm. Such core-shell structured nanoparticles can effectively improve the optical properties and weather resistance of the composite material.

[0012] Through the synergistic strengthening effect of nano-aramid fibers and TiO2@SiO2 core-shell particles, the 3-day strength is increased by 35-50%, effectively solving the problem of support timeliness. After the nano-aramid fibers (with a diameter of 50-80 nm) are grafted with carboxyl groups by plasma, the interfacial binding energy with the PVA / PAA matrix is increased by 2.3 times. f-CNTs (8-15 nm) and silk fibroin nanofibers form a "fiber-tubular" interlocking structure, generating a bridging effect during crack propagation. The TiO2@SiO2 core-shell particles (with a 10-20 nm inner core) serve as nucleation sites during the cement hydration process, accelerating the formation of C-S-H gel.

[0013] According to an embodiment of the present invention, the polymer matrix is a blend system of polyvinyl alcohol (PVA) and polyacrylic acid (PAA), where the degree of polymerization of polyvinyl alcohol is 1700-2400, the degree of alcoholysis is 88-99%, the molecular weight of polyacrylic acid is 80000-150000, and the mass ratio of polyvinyl alcohol to polyacrylic acid is 6:4-8:2. This blend system has good film-forming properties and mechanical properties, and can form a uniform composite structure with nanomaterials.

[0014] According to an embodiment of the present invention, the bio-based plasticizer is a cardanol-based epoxy plasticizer with an epoxy value of 0.25-0.45 eq / 100 g and a viscosity (at 25°C) of 800-1500 mPa·s. The use of the bio-based plasticizer can not only improve the flexibility of the composite material but also reduce the impact on the environment.

[0015] According to an embodiment of the present invention, the intelligent self-healing microcapsules have a melamine resin-polyurethane double-layer shell structure, with the outer melamine resin layer having a thickness of 0.5-1.0 μm, the inner polyurethane layer having a thickness of 0.2-0.5 μm, the core material being a mixture of epoxy resin E-51 and microencapsulated dicyandiamide curing agent in a mass ratio of 100:8-100:12, the microcapsule particle size being 20-50 μm, and the encapsulation efficiency being ≥90%. These microcapsules can release the curing agent when the material is damaged, realizing the self-healing function.

[0016] The melamine resin outer shell (0.5-1.0 μm) used in the present invention provides alkaline environment tolerance (stability at pH > 14), the polyurethane inner layer (0.2-0.5 μm) ensures controllable rupture during mechanical damage, and the microencapsulated dicyandiamide curing agent (particle size 2-5 μm) and epoxy resin E-51 form a latent curing system. The innovatively designed double-layer shell microcapsules precisely release the epoxy resin / curing agent system during crack propagation, achieving a mechanical property recovery of >85% within 48 hours, far exceeding the 60% repair rate of traditional materials.

[0017] According to an embodiment of the present invention, the amphiphilic block copolymer dispersant is of the PEO-PPO-PEO type, with a molecular weight of 8000-15000 and a PEO content of 60-80 wt%. This dispersant can effectively disperse nanomaterials, prevent their agglomeration, and improve the uniformity and stability of the composite material.

[0018] The epoxy group of the cardanol-based plasticizer undergoes a ring-opening reaction with the hydroxyl group of PVA. The PEO-PPO-PEO dispersant adsorbs nanomaterials and polymer matrix respectively through the block structure. The KH-550 silane coupling agent forms a Si-O-Si crosslinking network on the surface of nano-aramid fibers, and a three-dimensional barrier network is constructed by silk fibroin nanofibers and f-CNTs, reducing the chloride ion permeability coefficient by 60-80% and increasing the service life by more than 3 times.

[0019] According to the second aspect of the present invention, a tunnel anchor shotcrete support system is provided. The nano-aramid crystal glue modified polymer as described above is used as an additive for shotcrete, with a dosage of 1.0-3.0 wt%, and a microwave-infrared synergistic process is used for treatment.

[0020] According to an embodiment of the present invention, the microwave-infrared synergistic process includes: Microwave stage: frequency 2.45 GHz, power density 1.0-2.5 kW / m 3 , duration 1.0-2.5 h; Infrared stage: wavelength 3-5 μm, temperature 60-85 °C, relative humidity 60-80%, duration 4.0-8.0 h.

[0021] According to an embodiment of the present invention, the shotcrete also contains 0.05-0.15% of the retarder sodium gluconate and 0.01-0.03% of the air-entraining agent sodium dodecyl sulfate; When the concrete is damaged by microcracks of 0.1-0.3 mm, the self-healing efficiency of the intelligent self-healing microcapsules is ≥85% within 48 h, and the compressive strength recovery rate after 28 d of repair is ≥90%.

[0022] According to an embodiment of the present invention, the TiO2@SiO2 core-shell structured nanoparticles endow the concrete surface with photocatalytic performance. Under standard light conditions (AM1.5, 100 mW / cm 2 ), the degradation efficiency of NOx is ≥70%, and the degradation efficiency of methyl orange is ≥65%; The nano-aramid crystal glue modified polymer increases the 3d compressive strength of the concrete by 35-50%, the 28d flexural strength by 25-40%, and reduces the chloride ion permeability coefficient by 60-80%.

[0023] According to an embodiment of the present invention, the working performance of the shotcrete satisfies: slump 160 - 200 mm, spread 450 - 550 mm, initial setting time 3 - 5 h, final setting time 6 - 8 h; The support system can be normally constructed in an environment with a temperature of -20°C to 60°C and a relative humidity of 30 - 95%.

[0024] In the present invention, the addition of nano - aramid fibers, functionalized carbon nanotubes, and silk fibroin nanofibers significantly improves the compressive strength, tensile strength, and impact resistance of the shotcrete. Experiments show that the compressive strength of the shotcrete incorporated with nano - aramid crystal gum modified polymer can be increased by 30% - 50%, the tensile strength is increased by 20% - 30%, and the impact resistance is increased by 40% - 60%.

[0025] In the present invention, the use of nano - metal oxide / SiO2 mixed dispersion and bio - based plasticizer improves the weather resistance, chemical corrosion resistance, and freeze - thaw resistance of the shotcrete. The TiO2@SiO2 core - shell structure nanoparticles can effectively block ultraviolet rays and reduce the aging of the material; the bio - based plasticizer can improve the flexibility of the material and prevent cracking caused by dry shrinkage.

[0026] The addition of intelligent self - healing microcapsules in the present invention endows the shotcrete with self - healing ability. When the material is damaged by micro - cracks, the microcapsules rupture and release the curing agent, which reacts with the epoxy resin to form a new polymer network, repair the cracks, and extend the service life of the material.

[0027] In the present invention, the use of microwave - infrared synergistic process to treat the shotcrete can accelerate the hydration reaction of the concrete, shorten the curing time, and improve the early strength. At the same time, the addition of retarder and air - entraining agent can improve the workability and impermeability of the concrete, and reduce the segregation and bleeding phenomena during construction.

[0028] Both the bio - based plasticizer and silk fibroin nanofibers used in the present invention are renewable resources, which conform to the development trend of green building materials and reduce environmental pollution. Detailed implementation manners

[0029] The embodiment of the present application is directed to a nano - aramid crystal gum modified polymer and a tunnel shotcrete support system.

[0030] Example 1 Components and mass percentages: Pre - treated nano - aramid fibers: 3.0% Functionalized carbon nanotubes: 2.5% Silk fibroin nanofibers: 2.5% Nano - metal oxide / SiO2 mixed dispersion: 4.0% Polymer matrix: 85.0% Bio - based plasticizer: 1.8% Intelligent self - healing microcapsules: 0.5% Amphiphilic block copolymer dispersant: 0.1%

[0031] Example 2 Components and mass percentages: Pre - treated nano - aramid fiber: 8.5% Functionalized carbon nanotubes: 0.5% Silk fibroin nanofibers: 0.5% Nano - metal oxide / SiO2 mixed dispersion: 10.0% Polymer matrix: 65.0% Bio - based plasticizer: 0.8% Intelligent self - healing microcapsules: 6.0% Amphiphilic block copolymer dispersant: 0.5%

[0032] Example 3 Components and mass percentages: Pre - treated nano - aramid fiber: 5.0% Functionalized carbon nanotubes: 1.5% Silk fibroin nanofibers: 1.5% Nano - metal oxide / SiO2 mixed dispersion: 7.0% Polymer matrix: 75.0% Bio - based plasticizer: 1.2% Intelligent self - healing microcapsules: 3.5% Amphiphilic block copolymer dispersant: 0.3%

[0033] Example 4 Components and mass percentages: Pre - treated nano - aramid fiber: 6.0% Functionalized carbon nanotubes: 1.0% Silk fibroin nanofibers: 2.0% Nano - metal oxide / SiO2 mixed dispersion: 8.0% Polymer matrix: 72.0% Bio - based plasticizer: 1.0% Intelligent self - healing microcapsules: 4.0% Amphiphilic block copolymer dispersant: 0.4%

[0034] Example 5 Components and mass percentages: Pre - treated nano - aramid fiber: 7.0% Functionalized carbon nanotubes: 2.0% Silk fibroin nanofiber: 1.0% Nano metal oxide / SiO2 mixed dispersion: 9.0% Polymer matrix: 70.0% Bio-based plasticizer: 1.5% Smart self-repairing microcapsules: 5.0% Amphiphilic block copolymer dispersant: 0.2%

[0035] Example 6 Components and mass percentage: Pretreated nano-aramid fiber: 4.0% Functionalized carbon nanotubes: 1.8% Silk fibroin nanofibers: 1.2% Nano metal oxide / SiO2 mixed dispersion: 6.0% Polymer matrix: 78.0% Bio-based plasticizer: 1.4% Smart self-repairing microcapsules: 4.5% Amphiphilic block copolymer dispersant: 0.3% Comparative Example 1 Components and mass percentage (smart self-repairing microcapsules missing): Pretreated nano-aramid fiber: 5.0% Functionalized carbon nanotubes: 1.5% Silk fibroin nanofiber: 1.5% Nano metal oxide / SiO2 mixed dispersion: 7.0% Polymer matrix: 75.0% Bio-based plasticizer: 1.2% Amphiphilic block copolymer dispersant: 0.3% Comparative Example 2 Components and mass percentage (lacking functionalized carbon nanotubes): Pretreated nano-aramid fiber: 5.0% Silk fibroin nanofiber: 1.5% Nano metal oxide / SiO2 mixed dispersion: 7.0% Polymer matrix: 75.0% Bio-based plasticizer: 1.2% Smart self-repairing microcapsules: 3.5% Amphiphilic block copolymer dispersant: 0.3% Comparative Example 3 Components and mass percentage (using ordinary nano-SiO2 instead of TiO2@SiO2 core-shell structure nanoparticles): Pre-treated aramid nanofibers: 5.0% Functionalized carbon nanotubes: 1.5% Silk fibroin nanofibers: 1.5% Nanometal oxide / ordinary nano-SiO2 mixed dispersion: 7.0% Polymer matrix: 75.0% Bio-based plasticizer: 1.2% Intelligent self-healing microcapsules: 3.5% Amphiphilic block copolymer dispersant: 0.3% Comparative Example 4 Components and mass percentages (without adding bio-based plasticizer): Pre-treated aramid nanofibers: 5.0% Functionalized carbon nanotubes: 1.5% Silk fibroin nanofibers: 1.5% Nanometal oxide / SiO2 mixed dispersion: 7.0% Polymer matrix: 76.2% Intelligent self-healing microcapsules: 3.5% Amphiphilic block copolymer dispersant: 0.3% Experimental Example: In order to verify the performance of the aramid nanofiber crystal glue modified polymer in the tunnel anchor shotcrete support system in the above examples and comparative examples, systematic test detections were carried out. The following are the detailed test detection processes and results.

[0036] According to the formulations of each example and comparative example, aramid nanofibers, functionalized carbon nanotubes, silk fibroin nanofibers, nanometal oxide / SiO2 mixed dispersion, polymer matrix, bio-based plasticizer, intelligent self-healing microcapsules and amphiphilic block copolymer dispersant were mixed in proportion. The mixture was added to C30 shotcrete, and after stirring evenly, it was formed into standard specimens (150 mm × 150 mm × 150 mm cubes).

[0037] Treatment was carried out using a microwave-infrared synergistic process: microwave stage (frequency 2.45 GHz, power density 1.5 kW / m 3 , duration 2 h), infrared stage (wavelength 3 - 5 μm, temperature 75 °C, relative humidity 70%, duration 6 h).

[0038] 1. Mechanical property test: Compressive strength: Using a universal material testing machine, the compressive strengths at 3 d and 28 d were measured respectively under standard curing conditions (20 ± 2 °C, relative humidity above 95%).

[0039] Flexural strength: Similarly, under standard curing conditions, the flexural strength at 28 days was measured.

[0040] Tensile strength: Using the splitting tensile test method, the tensile strength at 28 days was measured.

[0041] Impact resistance: Using a pendulum impact testing machine, the impact resistance of the concrete was measured. The above results are shown in Table 1.

[0042]

[0043] Recovery rate of compressive strength after 28-day repair: The recovery rates of compressive strength after 28-day repair for all examples were above 90%, meeting the requirement (≥90%), indicating that the repaired concrete had a high strength recovery ability. The recovery rate of compressive strength after 28-day repair for Comparative Example 1 was only 30%, far lower than that of the examples. Although Comparative Examples 2, 3, and 4 had a certain recovery rate, they were significantly lower than those of the examples, indicating that each component had an important influence on the overall performance.

[0044] Increase in 3-day compressive strength: The increase range of 3-day compressive strength in the examples was 38% - 45%, meeting the requirement (35% - 50%), showing that the nano-aramid crystal gum modified polymer significantly improved the early strength. Comparative Example 1 only increased by 20%, far lower than that of the examples. Although Comparative Examples 2, 3, and 4 had some improvement, they were not as good as the examples, indicating that the roles of functionalized carbon nanotubes, TiO2@SiO2 core-shell structure nanoparticles, and bio-based plasticizers cannot be ignored.

[0045] Increase in 28-day flexural strength: The increase range of 28-day flexural strength in the examples was 28% - 35%, meeting the requirement (25% - 40%), indicating that the nano-aramid crystal gum modified polymer significantly enhanced the flexural performance of the concrete. Comparative Example 1 only increased by 15%, far lower than that of the examples. Although Comparative Examples 2, 3, and 4 had some increase, they were not as good as the examples, indicating that the synergistic effect of each component was crucial for enhancing the flexural performance.

[0046] Increase in tensile strength: The increase range of tensile strength in the examples was 24% - 29%, meeting the requirement (20% - 30%), indicating that the nano-aramid crystal gum modified polymer significantly enhanced the tensile performance of the concrete. Comparative Example 1 only increased by 10%, far lower than that of the examples. Although Comparative Examples 2, 3, and 4 had some increase, they were not as good as the examples, indicating that the synergistic effect of each component was very important for enhancing the tensile performance.

[0047] Improved impact resistance: The range of improved impact resistance in the examples is 48% - 56%, meeting the requirements (40% - 60%), indicating that the nano - aramid crystal rubber - modified polymer significantly enhances the impact resistance of concrete. In Comparative Example 1, the improvement is only 20%, far lower than that of the examples. Although there are improvements in Comparative Examples 2, 3, and 4, they are not as good as those of the examples, indicating that the synergistic effect of each component is crucial for improving the impact resistance.

[0048] 2. Self - healing efficiency test: Under standard curing conditions, micro - crack damages of 0.1 - 0.3 mm are induced in the concrete specimens.

[0049] The damaged specimens are placed in a standard curing environment, and the crack closure situation within 48 hours is observed and recorded.

[0050] The compressive strength after repair is measured, and the self - healing efficiency and the recovery rate of compressive strength are calculated.

[0051] 3. Durability test: Chloride ion penetration coefficient: The chloride ion penetration coefficient of the concrete is measured using the electric flux method.

[0052] Workability: The slump, spread, initial setting time, and final setting time are measured. The above results are shown in Table 2.

[0053]

[0054] Self - healing efficiency: The self - healing efficiency of all examples is above 85%, meeting the requirements (≥85%), indicating that the intelligent self - healing microcapsules have good self - healing effects when the concrete is damaged by micro - cracks of 0.1 - 0.3 mm. In Comparative Example 1 (lacking intelligent self - healing microcapsules), the self - healing efficiency is only 20%, significantly lower than that of the examples. In Comparative Examples 2, 3, and 4, although there is a certain self - healing ability, the effect is not as good as that of the examples, indicating that the synergistic effect of each component is crucial for self - healing.

[0055] Reduction of chloride ion penetration coefficient: The range of reduction of chloride ion penetration coefficient in the examples is 68% - 76%, meeting the requirements (60% - 80%), indicating that the nano - aramid crystal rubber - modified polymer significantly reduces the chloride ion permeability of the concrete. In Comparative Example 1, the reduction is only 30%, far lower than that of the examples. Although there are reductions in Comparative Examples 2, 3, and 4, they are not as good as those of the examples, indicating that the synergistic effect of each component is very important for reducing the chloride ion permeability.

[0056] Working performance: The slump range of the example is 170 - 190 mm, the spread range is 470 - 520 mm, the initial setting time is 3.5 - 4.5 hours, and the final setting time is 6.5 - 7.5 hours, all of which meet the working performance requirements (slump 160 - 200 mm, spread 450 - 550 mm, initial setting time 3 - 5 h, final setting time 6 - 8 h). Although the working performance of the comparative example also basically meets the requirements, generally it is not as good as the example, especially in terms of spread and setting time, showing slightly worse performance.

[0057] Through comparative analysis, it can be seen that the nano - aramid crystal glue - modified polymer in the example significantly improves various performance indicators of the concrete, especially showing excellent performance in self - repair efficiency, compressive strength, flexural strength, tensile strength, impact resistance and durability. In contrast, due to the lack of some key components, the performance of the comparative example is significantly lower than that of the example, verifying the importance and synergy of each component in the composite material. These experimental results provide strong data support for optimizing the formula. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0058] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A nano-aramid crystal glue modified polymer, characterized in that, It comprises the following components by mass percentage: Pre-treated nano aramid fiber: 3.0 - 8.5%; Functionalized carbon nanotubes: 0.5 - 2.5%; Silk fibroin nanofibers: 0.5 - 2.5%; Nano metal oxide / SiO2 mixed dispersion: 4.0 - 10.0%; Polymer matrix: 65.0 - 85.0%; Bio-based plasticizer: 0.8 - 1.8%; Intelligent self-healing microcapsules: 0.5 - 6.0%; Amphiphilic block copolymer dispersant: 0.1 - 0.5%.

2. The nano aramid crystal gum modified polymer according to claim 1, wherein: The diameter of the pre-treated nano aramid fiber is 50 - 80 nm, the aspect ratio is 2000 - 5000, and it is secondarily modified by plasma grafting carboxyl - COOH and silane coupling agent KH-550, and the grafting rate is 1.2 - 3.5 mol%; The functionalized carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 8 - 15 nm, a length of 10 - 30 μm, the surface grafted polyethylene glycol has a molecular weight of 2000 - 5000, and the grafting density is 0.8 - 1.6 per nm².

3. The nano aramid crystal gum modified polymer according to claim 1, wherein: The silk fibroin nanofibers are TEMPO-oxidized silk fibroin nanofibers with a diameter of 5 - 20 nm, a length of 1 - 3 μm, and a carboxyl content of 0.8 - 1.5 mmol / g.

4. The nano aramid crystal gum modified polymer according to claim 1, wherein: In the nano metal oxide / SiO2 mixed dispersion, it is a mixed dispersion of TiO2@SiO2 core-shell structure nanoparticles and ordinary nano SiO2, wherein the mass ratio of TiO2@SiO2 core-shell structure nanoparticles to ordinary nano SiO2 is 1.5:1 - 2.5:1, and the inner core particle size of TiO2 is 10 - 20 nm, and the SiO2 shell layer thickness is 2 - 5 nm.

5. The nano aramid crystal gum modified polymer according to claim 1, wherein: The polymer matrix is a blend system of polyvinyl alcohol and polyacrylic acid, wherein the polymerization degree of polyvinyl alcohol is 1700 - 2400, the degree of alcoholysis is 88 - 99%, the molecular weight of polyacrylic acid is 80000 - 150000, and the mass ratio of polyvinyl alcohol to polyacrylic acid is 6:4 - 8:

2.

6. The nano aramid crystal gum modified polymer according to claim 1, wherein: The bio-based plasticizer is a cardanol-based epoxy plasticizer with an epoxy value of 0.25 - 0.45 eq / 100 g and a viscosity of 800 - 1500 mPa·s.

7. The nano aramid crystal gum modified polymer according to claim 1, wherein: The intelligent self-healing microcapsules have a melamine resin - polyurethane double-layer shell structure, the outer melamine resin layer thickness is 0.5 - 1.0 μm, the inner polyurethane layer thickness is 0.2 - 0.5 μm, the core material is a mixture of epoxy resin E-51 and microencapsulated dicyandiamide curing agent in a mass ratio of 100:8 - 100:12, the microcapsule particle size is 20 - 50 μm, and the encapsulation rate ≥ 90%; The amphiphilic block copolymer dispersant is of the PEO-PPO-PEO type, with a molecular weight of 8,000 - 15,000 and a PEO content of 60 - 80 wt%.

8. A tunnel shotcrete support system, characterized in that: The nano-aramid crystal rubber modified polymer described in any one of claims 1 - 7 is used as an additive for shotcrete, with a dosage of 1.0 - 3.0 wt%, and a microwave-infrared synergistic process is used for treatment.

9. The tunnel shotcrete support system according to claim 8, characterized in that: The microwave-infrared synergistic process is adopted, including: Microwave stage: frequency 2.45 GHz, power density 1.0 - 2.5 kW / m³, duration 1.0 - 2.5 h; Infrared stage: wavelength 3 - 5 μm, temperature 60 - 85 °C, relative humidity 60 - 80%, duration 4.0 - 8.0 h.

10. The tunnel shotcrete support system according to claim 8, characterized in that: The shotcrete also contains 0.05 - 0.15% of the retarder sodium gluconate and 0.01 - 0.03% of the air-entraining agent sodium dodecyl sulfate.

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