A shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions, and its preparation method and application

Abstract

A shotcrete interface reinforcement mortar for use in cold-region tunnel water seepage conditions, and its preparation method and application, belong to the field of shotcrete technology. Its raw materials are as follows: cement, water, calcium salt, phase-change temperature control component, modified silane coupling agent, fine aggregate, liquid alkali-free quick-setting agent and water reducer, wherein the phase-change temperature control component is a mixture of emulsion polymer powder and adhesive, and the modified silane coupling agent is a nanomaterial-modified silane coupling agent. The present invention is specifically aimed at how to effectively improve the bonding strength and water penetration resistance of shotcrete in low-temperature environments when cold-region tunnels are facing low-temperature water seepage construction environments. This new idea not only focuses on solving key problems such as the decrease in concrete bonding strength and susceptibility to freeze-thaw damage, which are common in tunnel construction in cold regions, but also aims to fundamentally improve the bonding condition between concrete and construction surface through refined surface treatment technology, and enhance its ability to resist structural damage caused by low temperature and water penetration.

Description

Technical Field

[0001] The present invention relates to the technical field of shotcrete, and in particular to a shotcrete interface reinforcement mortar for use in water seepage conditions in cold-region tunnels, and a preparation method and application thereof. Background Art

[0002] Shotcrete, a highly efficient concrete construction technique, can quickly and evenly apply concrete to surfaces to be reinforced or repaired. It is particularly well-suited for initial tunnel support and slope stabilization and repair. The application of this technology not only significantly improves project construction efficiency and effectively reduces labor and material costs, but also ensures compliance with project quality and safety standards. Therefore, shotcrete plays a vital role in building and infrastructure construction. In high-altitude areas, winter tunnel construction often faces extreme temperature fluctuations, accompanied by severe water seepage, and even ice formation on the rock surface, which is extremely detrimental to construction. Low temperatures and water seepage not only hinder the early strength development of shotcrete, making it difficult to meet rapid construction and strength requirements, but also lead to unstable initial support due to water freezing and the retardation of hydration reactions within the concrete. Therefore, for tunnels in cold regions facing low temperatures and water seepage, effectively improving the bond strength and frost resistance of shotcrete can help ensure construction quality and safety, and provide strong support for the long-term stability and service life of the tunnel.

[0003] In order to reduce the rebound rate of shotcrete in tunnels with water seepage in cold regions, in-depth and systematic research on existing technologies has been conducted. These studies not only focus on the optimization of concrete mix ratios, but also cover multiple aspects such as construction control, equipment maintenance, and the application of new materials. For example, the Chinese patent application with publication number CN114853419 A discloses a low-rebound shotcrete for high-altitude railway tunnels and its preparation method. The rebound rate of shotcrete is greatly reduced by modifying mineral admixtures and modified fibers, making the rebound rate of shotcrete less than 12%, reducing a large amount of resource waste and achieving green and low-carbon construction. However, the fiber materials and admixtures used are prone to cause problems such as high viscosity of the concrete mixture and poor collapse resistance, which is not conducive to actual spraying.

[0004] Chinese patent application publication number CN115611585 A discloses a C25 anti-corrosion shotcrete for water-rich surrounding rock in tunnels, as well as its preparation and application methods. When applied to water-rich surrounding rock, this method effectively prevents voids and falling concrete, thereby improving construction quality and project safety. It also reduces concrete rebound, achieving energy savings and environmental benefits. However, relying solely on the toughening and strengthening effects of components like silica fume and polypropylene fiber, its practicality on low-temperature, humid rock surfaces remains to be determined.

[0005] Chinese patent application publication number CN118724540 A discloses a low-shrinkage, high-freeze-resistant shotcrete, its preparation method, and its application. Specifically, the invention discloses a low-shrinkage, high-freeze-resistant shotcrete made from solid waste materials. This method effectively promotes the resource and high-value utilization of solid waste, significantly reduces the volume shrinkage of shotcrete during the curing process, and significantly enhances its resistance to damage from low-temperature freeze-thaw cycles. However, while this solution significantly enhances low-temperature frost resistance, it does not consider the construction rebound rate under low-temperature water seepage conditions.

[0006] Chinese patent publication number CN118754581 A discloses a fast-setting, erosion-resistant shotcrete for water-rich tunnels, as well as its preparation method and application. Specifically, the patent discloses a method for preparing fast-setting, erosion-resistant shotcrete for water-rich tunnels by adding modified microsilica fume, a thickener admixture, and asphalt-based carbon fibers. This method effectively prevents various types of tunnel water inrush. However, this method inevitably increases the viscosity of the shotcrete and the construction difficulty, and it also requires the use of an accelerated-setting admixture with a more effective setting accelerator.

[0007] Chinese patent publication number CN108756939 B discloses a system and method for heating the sprayed concrete and accelerator used in shotcrete construction. Pressurized air and / or accelerator heated by a heating device are mixed with the materials in the concrete sprayer and then sprayed through a nozzle to complete the construction. By heating the sprayed concrete and accelerator, the amount of accelerator used can be effectively reduced, the final setting time can be shortened, the rebound effect can be reduced, and work efficiency can be improved. However, this method involves modifying the wet sprayer, and the insulation effect of air pressure / concrete temperature rise time needs to be explored.

[0008] Therefore, there is an urgent need to develop a shotcrete construction method suitable for tunnels in cold regions with water seepage. This method, while ensuring the construction performance of shotcrete, also addresses the problems of poor concrete setting and increased concrete rebound at low temperatures. This ensures construction quality and safety, and provides strong guarantees for the long-term stability and service life of the tunnel. Summary of the Invention

[0009] Technical problem to be solved: In response to the problems of poor adhesion and high rebound rate of shotcrete in the prior art under water seepage conditions in cold regions, the present invention provides a shotcrete interface reinforcement mortar for use in water seepage conditions in cold region tunnels, as well as a preparation method and application thereof. It is specifically designed for cold region tunnels facing low-temperature water seepage construction environments, and can effectively improve the bonding strength of shotcrete and reduce the rebound rate of shotcrete.

[0010] Technical solution: The first object of the present invention is to provide a shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions, wherein the raw materials are proportioned as follows by mass: 480-520 parts of cement, 160-180 parts of water, 20-40 parts of calcium salt, 2-10 parts of temperature control component, 4-8 parts of modified silane coupling agent, 800-900 parts of fine aggregate, 30-45 parts of liquid alkali-free accelerating agent and 4-6 parts of water reducing agent, wherein the calcium salt is at least one of calcium sulfate, calcium formate and calcium acrylate. One method comprises the following steps: a temperature control component is a mixture of emulsion polymer powder and an adhesive, the mass ratio of the emulsion polymer powder to the adhesive is 0.8-1.2:1.6-2.4, the modified silane coupling agent is a nanomaterial-modified silane coupling agent, the nanomaterial is at least one of nano-silicon dioxide, nano-aluminum oxide, nano-calcium carbonate and nano-titanium oxide, and the silane coupling agent is tetraethoxysilane, γ-aminopropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane or tridecafluorooctyltrimethoxysilane.

[0011] The calcium salt in the present invention is at least one of calcium sulfate, calcium formate and calcium acrylate. Preferably, the calcium salt is calcium acrylate. The polar groups -COOCa and -OH in calcium acrylate can react with the Ca in cement. 2+ 、Al 3+ When added to the interface reinforcement mortar, it aggregates on the rock surface and further forms a network system, overlapping with another network system formed by concrete, thus strengthening the bonding strength between the tunnel construction surface and the concrete.

[0012] Preferably, the cement is ordinary Portland cement with a strength grade of ≥42.5.

[0013] Preferably, the fine aggregate is machine-made sand, river sand or mixed sand.

[0014] As a preference, the fine aggregate fineness modulus is 2.7-3.2, the mud content is less than 0.5%, the water absorption rate is less than 0.5%, and the apparent density is 2600-2650 kg / m 3 , bulk density is 1500-1550 kg / m 3 .

[0015] Preferably, the liquid alkali-free quick-setting agent is a high-activity aluminum phase fluorine-free alkali-free quick-setting agent, and the water reducer is a polycarboxylic acid high-efficiency water reducer.

[0016] Furthermore, the polycarboxylic acid high-efficiency water-reducing agent has a water-reducing efficiency greater than 20% and a solid content of 15-20%.

[0017] Preferably, the high-activity aluminum phase fluorine-free and alkali-free quick-setting agent has an initial setting time of <3 min, a final setting time of <10 min, and a 1-day mortar compressive strength of >10 MPa, which is much higher than the performance requirements of the enterprise standard GB / T 35159-2017 for quick-setting agents.

[0018] Preferably, the emulsion polymer powder is polyvinyl acetate powder, vinyl acetate-ethylene powder or styrene-butadiene emulsion polymer powder, and the adhesive is acrylic adhesive, polyurethane adhesive or organic silicone adhesive.

[0019] Furthermore, the emulsion polymer powder is vinyl acetate-ethylene powder, and the adhesive is an acrylate adhesive. The temperature-control component can form a high-strength silicone gel cluster layer within the interface-reinforced mortar. When the ambient temperature approaches the phase change point of the phase change material (<10°C), the phase change material solidifies and releases a large amount of heat, slowing down temperature changes.

[0020] Preferably, the preparation method of the nanomaterial-modified silane coupling agent is as follows: adding nanomaterial and deionized water in a mass ratio of 0.5-1.5:15-25 to a reaction container, performing hydrothermal treatment at 70-90° C. and constant temperature stirring at 1000 r / min for 4-7 hours, then adding the hydrothermally treated nanomaterial and silane coupling agent in a mass ratio of 1.2-1.4:0.8-1.2 to the reaction container, and stirring at a constant temperature of 500 r / min for 20-24 hours at 20-30° C. to obtain the nanomaterial-modified silane coupling agent.

[0021] Furthermore, nano-calcium carbonate was selected as the nanomaterial. Tridecafluorooctyltrimethoxysilane was selected as the silane coupling agent. Hydrolysis of the silane coupling agent produces methanol, which is detrimental to the hydration of cement particles. The silane coupling agent modified with nano-calcium carbonate hydrolyzes in an alkaline environment to produce silanol groups. These silanol groups further undergo a dehydration condensation reaction with alkaline substances in the concrete, forming stable silicon-oxygen bonds and improving interfacial adhesion. Furthermore, the strong hydrophobicity of tridecafluorooctyltrimethoxysilane prevents water erosion from the tunnel's seeping rock walls on the hardened mortar / concrete.

[0022] A second object of the present invention is to provide a method for preparing the above-mentioned shotcrete interface reinforcement mortar for use in water seepage conditions in cold-region tunnels, comprising the following steps: adding cement, calcium salt, fine aggregate, water, and a water reducer into a mixer and stirring uniformly; then adding a temperature control component and a modified silane coupling agent into the mixer and continuing to stir until uniformly mixed; then loading the mixed mortar into a concrete sprayer; adding a liquid alkali-free accelerating setting agent at the nozzle; and then spraying the mortar for construction.

[0023] The third object of the present invention is to provide the use of the above-mentioned shotcrete interface reinforcement mortar for cold region tunnel water seepage conditions as a construction material for interface reinforcement mortar under cold region tunnel water seepage conditions. During construction, the shotcrete interface reinforcement mortar for cold region tunnel water seepage conditions except for the liquid alkali-free quick-setting agent is loaded into a concrete spraying machine, the liquid alkali-free quick-setting agent is added at the nozzle, and sprayed 1 to 2 cm to the cold region tunnel construction surface to complete the interface reinforcement mortar construction.

[0024] Beneficial effects: (1) The polar groups (-COOCa and -OH) in the calcium salt of the present invention, especially in the calcium acrylate, can react with the ions (Ca 2+ 、Al 3+ ) reacts, forming a network system on the rock surface that overlaps with the concrete network. This interaction significantly strengthens the bond between the tunnel construction surface and the concrete, enhancing the overall structural stability and durability. The nanomaterial-modified silane coupling agent hydrolyzes in an alkaline environment to generate silanol groups, which undergo a dehydration condensation reaction with alkaline substances in the concrete to form stable silicon-oxygen bonds, thereby strengthening the interfacial adhesion. Simultaneously, the highly hydrophobic components in the modified silane coupling agent effectively hinder the erosion of water from the tunnel's seeping rock walls on the hardened mortar / concrete, protecting the structure from moisture damage. The temperature-controlling components in the interface-reinforcing mortar solidify at low temperatures near the phase transition point, releasing significant heat and slowing temperature fluctuations. This temperature-stabilizing effect helps mitigate the negative impact of temperature fluctuations on the mortar / concrete structure, improving its stability and durability, which is particularly important in extreme climates.

[0025] (2) The technical solution of the present invention integrates advanced material modification, surface pretreatment technology and environmental adaptability design, aiming to ensure that even under extremely harsh cold-zone tunnel climate conditions, shotcrete can exhibit excellent bonding stability and outstanding frost resistance. This innovation not only provides solid technical support for the safe construction and long-term stable operation of tunnel projects, but also opens up new paths for the construction of other key infrastructure such as bridges, water conservancy hubs, and underground integrated pipelines in cold regions, showing an extremely broad and potential application prospect. With the further development and promotion of this technology, it is expected to play an immeasurable positive role in improving the quality of facility construction in cold regions, accelerating construction progress, and reducing maintenance costs. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to specific embodiments.

[0027] In order to more fully illustrate the core concept and application effects of the present invention, we will provide a detailed description with reference to specific embodiments. The raw materials in this embodiment are all commercially available, and the manufacturers and related models are as follows:

[0028] The cement was purchased from Southwest Cement Co., Ltd., model P·O 42.5 cement. The water reducer and liquid alkali-free accelerating admixture were both purchased from Jiangsu Subote New Materials Co., Ltd., model PCA®-Ⅰ series polycarboxylate high-efficiency water reducer and SBT-N(Ⅱ) liquid accelerating admixture, respectively. The fine aggregate was river sand with a fineness modulus of 2.9, a mud content of <0.5%, a water absorption rate of <0.5%, and an apparent density of 2630 kg / m 3 , bulk density is 1525 kg / m 3 The coarse aggregate is single-particle crushed stone with a size of 5-10 mm.

[0029] The calcium acrylate was purchased from Hubei Xinghengye Technology Co., Ltd.; the vinyl acetate-ethylene powder was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd.; the acrylic adhesive was purchased from Dongguan Guangnong Adhesive Co., Ltd.; the tridecafluorooctyltrimethoxysilane was purchased from Hangzhou Jessica Chemical Co., Ltd.; and the nano-calcium carbonate was purchased from Hubei Huifu Nanomaterials Co., Ltd.

[0030] The preparation method of the interface reinforcement mortar in Examples 1 to 7 and Comparative Examples 1 to 5 is as follows:

[0031] 1. Prepare a modified silane coupling agent by adding nano-calcium carbonate and deionized water in a mass ratio of 1:12 into a flask, stirring at 85°C and 1000 r / min for 6 hours for hydrothermal reaction, then add the hydrothermally treated nano-calcium carbonate and the silane coupling agent tridecafluorooctyltrimethoxysilane into the flask in a mass ratio of 1.2:1, stirring at 25°C and 500 r / min for 22 hours to obtain a nanomaterial-modified silane coupling agent.

[0032] 2. Prepare the temperature control component by mixing vinyl acetate-ethylene powder and acrylic adhesive in a mass ratio of 1:2 to complete the preparation process.

[0033] 3. Add the weighed cement, calcium salt (calcium acrylate), fine aggregate, water, and water reducer into the mixer and stir at a stirring speed of 20 r / min for 90 seconds until uniform. Then add the temperature control component and modified silane coupling agent and continue stirring for 30 seconds until uniform.

[0034] 4. Load the prepared interface reinforcement mortar into the concrete spraying machine, add the accelerating agent at the nozzle, and spray 1~2cm to the tunnel construction surface to complete the interface reinforcement mortar construction.

[0035] The preparation method of shotcrete for the tunnel construction surface is as follows: the same batch of raw materials as the interface reinforcement mortar in the embodiment: cement, fine aggregate, coarse aggregate, water and water reducing agent are added to a mixer and mixed evenly, and then loaded into a concrete wet spraying machine, and an accelerator is added at the nozzle. The concrete is sprayed to the designed thickness of the tunnel construction surface (15 cm). The concrete is completely hardened within 30 minutes, and the shotcrete construction is completed to obtain the cold region tunnel construction surface.

[0036] Tables 1 and 2 below show the raw material components and mix ratio parameters of the interface reinforcement mortar and shotcrete provided in the examples and comparative examples.

[0037] Table 1 Raw material components of interface reinforcement mortar in comparative examples and examples (kg / m 3 )

[0038]

[0039] Table 2 Raw material composition of shotcrete (tunnel construction surface) in comparative examples and examples (kg / m 3 )

[0040]

[0041] The preparation methods of Examples 1 to 7 and Comparative Examples 1 to 4 are the same, except that the components in the interface reinforcement mortar are changed, while the shotcrete used has the same mix ratio.

[0042] Example 1

[0043] The interface strengthening mortar in this embodiment does not contain temperature control components and modified silane coupling agents.

[0044] Example 2

[0045] The interface strengthening mortar in this embodiment does not contain calcium acrylate and modified silane coupling agent.

[0046] Example 3

[0047] The interface strengthening mortar in this embodiment does not contain calcium acrylate and temperature control components.

[0048] Example 4

[0049] The interface reinforcement mortar in this embodiment does not contain a modified silane coupling agent.

[0050] Example 5

[0051] In this embodiment, the interface strengthening mortar does not contain calcium acrylate.

[0052] Example 6

[0053] In this embodiment, the interface strengthening mortar does not contain a temperature control component.

[0054] Example 7

[0055] This embodiment is a complete interface reinforcement mortar component.

[0056] Example 8

[0057] The same as Example 7, except that, in this example, 480 parts of cement, 160 parts of water, 20 parts of calcium salt, 2 parts of temperature control component, 4 parts of modified silane coupling agent, 800 parts of fine aggregate, 30 parts of liquid alkali-free quick-setting agent and 4 parts of water reducer are used.

[0058] Example 9

[0059] The same as Example 7, except that, in this example, 520 parts of cement, 180 parts of water, 40 parts of calcium salt, 10 parts of temperature control component, 8 parts of modified silane coupling agent, 900 parts of fine aggregate, 45 parts of liquid alkali-free quick-setting agent and 6 parts of water reducer are included.

[0060] Comparative Example 1

[0061] This comparative example does not contain interface reinforcing mortar.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that the calcium salt in this comparative example is calcium formate, while the calcium salt in Example 1 is calcium acrylate.

[0064] Comparative Example 3

[0065] This comparative example differs from Example 2 in the temperature-control components. The temperature-control component ratio (by mass) in Comparative Example 3 is: polypropylene acetate powder: silicone adhesive = 1:2. In Example 2, the temperature-control component ratio (by mass) is: vinyl acetate-ethylene powder: acrylic adhesive = 1:2.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 3 is that the silane coupling agent used in the modified silane coupling agent is different. The silane coupling agent in this comparative example uses tetraethoxysilane, while the silane coupling agent in Example 3 uses tridecafluorooctyltrimethylsilane.

[0068] Comparative Example 5

[0069] The difference between this comparative example and Example 7 is that the amounts (mass) of the calcium salt, the temperature control component and the modified silane coupling agent are different. In this comparative example, the ratio of calcium salt:temperature control component:modified silane coupling agent is 20:3:4, while in Example 7, the ratio of calcium salt:temperature control component:modified silane coupling agent is 25:5:6.

[0070] Performance testing:

[0071] To verify the low-temperature construction performance of the shotcrete interface reinforcement mortar for use in cold-region tunnel water seepage conditions, as well as its preparation method and application provided in the above-mentioned embodiments and comparative examples of the present invention, a bond strength test was conducted on core-drilled shotcrete with reference to Appendix M of the standard GB / T 50086-2015 "Technical Specification for Geotechnical Anchor and Shotcrete Support Engineering"; the anti-permeability performance of shotcrete was tested with reference to the water seepage height method in the standard GB / T 50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete"; the real-time temperature of the tunnel construction surface 10 minutes after the interface reinforcement mortar was sprayed was measured using a Leitai ST60+ infrared thermometer; and the actual rebound rate of shotcrete was tested with reference to Appendix G of the standard JGJ / T 372-2016 "Technical Specification for Application of Shotcrete".

[0072] Table 3 is a table showing various performance tests of tunnel interface reinforcement mortar composite shotcrete according to Examples 1 to 7 and Comparative Examples 1 to 5.

[0073] Table 3 Performance test of tunnel interface reinforcement mortar composite shotcrete

[0074]

[0075] Combining Example 1, Example 3, Example 6 and Comparative Example 1 and Comparative Example 2, it can be seen that the use of calcium acrylate has higher bonding strength than calcium formate, and the composite effect of calcium acrylate and modified silane coupling agent can enhance the bonding strength between shotcrete and tunnel rock formation.

[0076] Combining Examples 2, 4, and 5 with Comparative Examples 1 and 3, it can be seen that adding the temperature-control component can increase the construction surface temperature by approximately 10°C. Furthermore, the combination of vinyl acetate-ethylene powder and acrylic adhesive has even better temperature rise performance.

[0077] Combining Example 3, Example 5, Example 6 and Comparative Example 1 and Comparative Example 4, it can be seen that the interfacial hydrophobic effect of the modified silane coupling agent can enhance the water penetration resistance of the shotcrete, and the use of tridecafluorooctyltrimethylsilane has stronger hydrophobicity than tetraethoxysilane.

[0078] Combining Examples 4 to 7 and Comparative Examples 1 and 5, it can be seen that the use of interface reinforcing mortar can increase the construction surface temperature, enhance the bond strength and water permeability resistance, and reduce the rebound rate of shotcrete. Reducing the amount of calcium salt, temperature control component and modified silane coupling agent will weaken these properties.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions, characterized in that: The raw materials are proportioned as follows by mass: 480-520 parts of cement, 160-180 parts of water, 20-40 parts of calcium salt, 2-10 parts of temperature control component, 4-8 parts of modified silane coupling agent, 800-900 parts of fine aggregate, 30-45 parts of liquid alkali-free quick-setting agent and 4-6 parts of water reducer, wherein the calcium salt is calcium acrylate, the temperature control component is a mixture of emulsion polymer powder and adhesive, the mass ratio of the emulsion polymer powder to the adhesive is 0.8-1.2:1.6-2.4, the emulsion polymer powder is vinyl acetate-ethylene powder, the adhesive is acrylate adhesive, the modified silane coupling agent is a nanomaterial modified silane coupling agent, the nanomaterial is nano calcium carbonate, and the silane coupling agent is tridecafluorooctyltrimethoxysilane.

2. The shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions according to claim 1, characterized in that: The cement is ordinary Portland cement with a strength grade of ≥42.

5.

3. The shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions according to claim 1, characterized in that: The fine aggregate is machine-made sand, river sand or mixed sand.

4. The shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions according to claim 3, characterized in that: Fine aggregate fineness modulus 2.7~3.2, mud content <0.5%, water absorption <0.5%, apparent density 2600-2650kg / m 3 , bulk density is 1500-1550 kg / m 3 .

5. The shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions according to claim 1, characterized in that: The liquid alkali-free quick-setting agent is a high-activity aluminum phase fluorine-free alkali-free quick-setting agent, and the water reducer is a polycarboxylic acid high-efficiency water reducer.

6. The shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions according to claim 5, characterized in that: The high-activity aluminum phase fluorine-free and alkali-free quick-setting agent has an initial setting time of less than 3 minutes, a final setting time of less than 10 minutes, and a 1-day compressive strength of the quick-setting agent mortar of more than 10 MPa.

7. The shotcrete interface reinforcement mortar for use in tunnel water seepage conditions in cold regions according to claim 1, characterized in that: The preparation method of the nanomaterial-modified silane coupling agent is as follows: adding nanomaterial and deionized water in a mass ratio of 0.5-1.5:15-25 into a reaction container, performing hydrothermal treatment at 70-90°C with constant temperature stirring at 1000 r / min for 4-7 hours, then adding the hydrothermally treated nanomaterial and silane coupling agent in a mass ratio of 1.2-1.4:0.8-1.2 into the reaction container, and stirring at a constant temperature of 20-30°C with 500 r / min for 20-24 hours to obtain the nanomaterial-modified silane coupling agent.

8. The method for preparing the sprayed concrete interface reinforcement mortar for use in cold region tunnel water seepage conditions according to any one of claims 1 to 7, characterized in that: The steps are as follows: add cement, calcium salt, fine aggregate, water and water reducer into the mixer and mix evenly, then add temperature control component and modified silane coupling agent into the mixer and continue to mix until evenly mixed, then load the mixed mortar into the concrete sprayer, add liquid alkali-free quick-setting agent at the nozzle, and start spraying construction.

9. Use of the shotcrete interface reinforcement mortar for cold region tunnel water seepage conditions according to any one of claims 1 to 7 as a construction material for interface reinforcement mortar for cold region tunnel water seepage conditions, characterized in that: During construction, the shotcrete interface reinforcement mortar for cold region tunnel seepage conditions, except for the liquid alkali-free quick-setting agent, is loaded into the concrete spraying machine, the liquid alkali-free quick-setting agent is added at the nozzle, and the mortar is sprayed 1 to 2 cm to the construction surface of the cold region tunnel to complete the interface reinforcement mortar construction.

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