High-strength inorganic airtight reinforcing material and preparation method thereof

Abstract

The invention relates to the technical field of inorganic materials, in particular to a high-strength inorganic airtight reinforcing material and a preparation method of the high-strength inorganic airtight reinforcing material. The component A comprises the following components in parts by mass: 35-45 parts of silicate superfine cement, 10-15 parts of pozzolanic superfine cement, 10-15 parts of fly ash, 5-10 parts of bentonite, 4-5 parts of silica fume, 0.2-0.5 part of microfibers, 2-5 parts of a waterproof agent and 0.5-1 part of a water reducing agent; the component B comprises the following components in parts by weight: 10-15 parts of water glass, 2-5 parts of silica sol, 0.2-0.5 part of an anti-salt agent and water; a component C: 0.5-1 part of environmental response type functional microspheres; through combination of the environmental response type functional microspheres and the inorganic reinforcing material, when the grouting material is applied to water-absorbing rock stratum geology, a water loss path can be blocked, water migration can be reduced, the water loss rate of the grouting material can be effectively controlled, and the situation of swelling instability caused by excessive water absorption of a rock stratum is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic materials, and in particular to a high-strength inorganic closed reinforcement material and a preparation method thereof. Background Art

[0002] During tunnel construction, the rock formations on the excavation surface need to be pre-reinforced to prevent construction safety risks caused by rock collapse and groundwater infiltration. The commonly used rock reinforcement method is generally a combination of anchor rods and reinforcement slurry. The anchor rods are driven into the rock formations around the excavation surface, and then the pre-mixed reinforcement slurry is injected into the anchor rods. It penetrates into the surrounding rock formations through the holes on the anchor rods, and forms a grip with the rock formation after solidification. It has high-strength reinforcement capabilities, and the slurry that penetrates into sheets also has a sealing effect on groundwater.

[0003] When constructing tunnel projects in water-absorbing rock formations, due to the special composition of the water-absorbing rock formations, they can easily absorb moisture from the grouting materials, causing the water in the slurry to be lost too quickly, seriously affecting the water-cement ratio and workability of the slurry. In addition, the rock formations that absorb a lot of water can easily expand and become unstable, causing deformation, cracking or spalling of the surrounding rock. In severe cases, collapse in the tunnel can occur, affecting construction safety.

[0004] Therefore, in order to solve the above problems, a reinforcement material can be designed to effectively prevent the rock strata from absorbing water under the geological conditions of water-absorbing rock strata, thereby improving the safety of tunnel construction under such geological conditions. Summary of the Invention

[0005] In order to overcome the problem that the grouting reinforcement materials used in tunnel construction projects in the geological environment of water-absorbing rock strata are easily absorbed by the rock strata, which not only causes the loss of moisture in the grouting materials and affects their chemical properties, but also leads to the redistribution of stress within the rock structure and even causes deformation, cracking or spalling of the surrounding rock, affecting the safety of tunnel construction.

[0006] The technical solution of the present invention is: a high-strength, waterproof, closed reinforcement material, composed of the following components in parts by mass: component A: 35-45 parts of silicate ultrafine cement, 10-15 parts of pozzolanic ultrafine cement, 10-15 parts of fly ash, 5-10 parts of bentonite, 4-5 parts of silica fume, 0.2-0.5 parts of fine fibers, 2-5 parts of waterproofing agent and 0.5-1 part of water reducer; component B: 10-15 parts of water glass, 2-5 parts of silica sol and 0.2-0.5 parts of salt-resistant agent, water; component C: 0.5-1 part of environmentally responsive functional microspheres.

[0007] Preferably, the silicate ultrafine cement is P·O 52.5 grade cement, the pozzolanic ultrafine cement is P·P 42.5 grade cement, and the fly ash loss on ignition is ≤8%.

[0008] Using P·O 52.5 grade silicate ultrafine cement (which can provide early strength of grouting materials) and P·P42.5 grade pozzolanic ultrafine cement (pozzolanic ultrafine cement has good late strength development and is suitable for use in water-absorbing rock geology that requires long-term stability, and its chemical stability such as salt resistance is also good) as the skeleton of the cementitious material, it can reduce the hydration heat, improve durability, corrosion resistance and impermeability (in actual application, silicate ultrafine cement can also be partially replaced by sulphoaluminate cement clinker, and volcanic ash ultrafine cement can be replaced by adding mineral powder). To a certain extent, It can also improve the salt resistance and rapid setting properties of the grouting material, reduce the amount of water absorbed by the water-absorbing rock formation in the grouting material, and fly ash with a loss on ignition of ≤8% can effectively improve the workability of the grouting material (too high a loss on ignition will affect the strength and durability of the grouting material, and fly ash with a lower loss on ignition can help maintain the good workability and fluidity of the grouting material, making it easier to pump and fill tiny cracks. It also helps to improve the density and impermeability of the slurry, enhance the durability of the overall structure, and is particularly suitable for the reinforcement of water-absorbing rock formations) and improve the later strength.

[0009] Preferably, the bentonite is sodium bentonite, with a montmorillonite content of ≥80% and a CEC of 70-100 meq / 100g.

[0010] Compared with calcium-based bentonite, sodium-based bentonite has a stronger water absorption and expansion capacity. It can absorb water several times its own weight to form a stable gel-like substance with good suspension stability and viscosity. It is more suitable for the water-absorbing rock formations that require high airtightness in the present invention, and provides the grouting material with high expansion and water retention (it is worth noting that the dosage needs to be strictly controlled during the preparation process to avoid excessive water absorption. In actual applications, it can also partially replace organic bentonite to improve salt resistance).

[0011] Preferably, the silica fume has a silica content of ≥85% and a specific surface area of ​​≥17,000 cm 2 / g, water content ≤3%.

[0012] By filling the tiny gaps between cement particles with highly active silica fume to form a dense structure, the compressive and tensile strengths of the grouting material after solidification can be enhanced, and the impermeability and strength of the grouting material can be improved (in actual applications, it can be partially replaced by nano-silica to obtain a smaller particle size and a better filling effect).

[0013] Preferably, the microfiber is a composite fiber composed of polypropylene fiber and steel fiber, wherein the polypropylene fiber accounts for 60% to 70% of the total microfiber content, and the steel fiber accounts for 30% to 40% of the total microfiber content.

[0014] The composite fiber composed of polypropylene fiber (which has good chemical stability and is not easily damaged in the salt environment of water-absorbing rock formations) and steel fiber can enhance the crack resistance and tensile strength of the grouting material after solidification. It can also reduce the shrinkage cracks caused by changes in ambient temperature after the grouting material is solidified, prevent the segregation and water exudation of the grouting material, and reduce the amount of water absorbed by the water-absorbing rock formation in the grouting material. At the same time, the addition of steel fiber can also produce mechanical bite between the grouting anchor rod and improve the bonding degree between the grouting material and the anchor rod.

[0015] Preferably, the waterproofing agent is a cement-based penetrating crystallization waterproofing agent, and the water reducer is a polycarboxylic acid water reducer.

[0016] Penetrating crystallization type waterproofing agent can form a crystal layer in the grouting material to ensure the material's impermeability. It can generate insoluble crystals through chemical reactions to fill tiny cracks and has a certain self-healing ability. It not only forms a waterproof layer on the surface of the cement substrate, but also penetrates into the interior of the cement substrate to provide deeper protection. It is suitable for tunnel underground projects in the water-absorbing rock environment of the present invention. The polycarboxylate water-reducing agent has high water reduction efficiency and good collapse resistance. It ensures the fluidity of the grouting material while greatly reducing water consumption (fundamentally reducing the absorption of water in the slurry by the water-absorbing rock formation). During the grouting process, it prevents the slurry from becoming viscous and affecting the pressure output of the pumping equipment.

[0017] Preferably, the water glass modulus is 2.0 to 3.5, the density is 40 to 42° Bé, the silica sol particle size is 10 to 20 nanometers, the pH value is 7 to 9, and the solid content is 25% to 30%.

[0018] Specifically considering the needs of water-absorbing rock formations, water glass with a modulus of 2.5 to 3.0 is selected to ensure a faster setting speed and facilitate rapid solidification with water-absorbing rock formations. Water glass reacts with silicate ultrafine cement and volcanic ash ultrafine cement to form calcium silicate gel, which improves early strength and provides rapid solidification and adhesion properties for grouting materials. Taking into account the needs of water-absorbing rock formations, neutral or weakly alkaline silica sol with a pH value of 7 to 9 can avoid adverse effects on other components and help adjust the pH value of the overall slurry to prevent excessive alkalinity from causing expansion or other problems. A solid content of 20% to 30% can provide sufficient active ingredients without significantly increasing the viscosity of the slurry. Nano-silica sol fills the micro-cracks in the water-absorbing rock formation, improves the density of the rock formation after grouting, and can also enhance impermeability and durability.

[0019] Preferably, the environmentally responsive functional microspheres are sodium alginate microspheres, and the anti-salt agents are hydroxymethyl cellulose and calcium silicate.

[0020] Sodium alginate microspheres are used in water-absorbent rock formations in low-salt environments (calcium ion cross-linked microspheres or polyacrylamide-based microspheres can also be used in actual applications). Through their property of expanding when exposed to water to form a sealing layer, a physical barrier is formed. By occupying the pore space of the rock formation, the loss of slurry water is reduced, and the sealing effect of the rock formation after the grouting material is cured is improved. At the same time, hydroxymethyl cellulose and calcium silicate are needed as salt-resistant agents to retain water in a low-salt environment, forming a double barrier with the sodium alginate microspheres.

[0021] Preferably, the environmentally responsive functional microspheres are chitosan composite microspheres, and the anti-salt agent is acrylamide copolymer and EDTA.

[0022] Chitosan composite microspheres are used in water-absorbing rock formations in high-salt environments (sodium alginate microspheres cannot be used at this time, as they will shrink or dehydrate due to osmosis in a high-salt environment, causing them to lose their ability to expand or even release water, which may in turn aggravate the rock formation's absorption of slurry water. In actual applications, salt-resistant cross-linked polyelectrolyte microspheres can also be used). These microspheres have good salt resistance and can work synergistically with acrylamide copolymers and EDTA to thicken and resist salt, doubly inhibit salt ion interference, and stabilize the structure of chitosan composite microspheres.

[0023] The present invention provides a method for preparing a high-strength, non-combustible, sealed reinforcement material, which comprises the following steps:

[0024] S101: pre-treating the water glass, including adding EDTA chelating agent at a rate of 0.05% to 0.1% of the mass of the water glass, stirring for 10 to 15 minutes, standing and filtering, and storing the water glass solution at room temperature;

[0025] By adding EDTA to chelate metal ions (such as Fe 3+ 、Al 3+ ), can reduce the turbidity of water glass and improve the stability of water glass. In practical applications, citric acid can also be used instead of EDTA, which is more environmentally friendly. The water glass that has been treated with impurities can further avoid adverse chemical reactions caused by impurities or reduce the stability of the slurry.

[0026] S102: pre-treating the silica sol, including adding activated carbon at a rate of 0.2% to 0.5% of the mass of the silica sol, stirring for 30 minutes, filtering, reserving the silica sol solution, and adding a small amount of NaOH or citric acid to adjust the pH value of the silica sol to a range of 7 to 9;

[0027] By adding activated carbon, impurities in the silica sol are adsorbed, and the pH is adjusted to avoid colloid precipitation and ensure the dispersibility of the silica sol. In practical applications, ultrasonic treatment can also be used to disperse and remove tiny particle impurities in the silica sol to improve the purity of the solution.

[0028] S103: Pre-treating the bentonite, including mixing the bentonite with water and stirring for 30 minutes to form a uniform slurry for later use;

[0029] Pre-treating the bentonite in advance can ensure its uniform dispersion and prevent stratification after the slurry is prepared.

[0030] S104: Pre-treating the microfibers, including wetting the surface with an active agent or spraying water;

[0031] Using an activator or spray water to wet the fine fibers can effectively prevent fiber agglomeration caused by static electricity. The activator can specifically be a silane coupling agent or other materials.

[0032] S105: Selecting appropriate environmentally responsive functional microspheres according to the salinity of the water-absorbing rock formation and pre-treating the environmentally responsive functional microspheres, including dispersing the microspheres in water, adding a silane coupling agent, and stirring at a speed of 50-150 rpm until the microspheres are completely dispersed without agglomeration, thereby obtaining component C material;

[0033] The adhesion between the environmentally responsive functional microspheres and the A component material and the B component material can be improved by stirring and dispersing, thereby preventing the microspheres from settling.

[0034] S201: Weigh silicate ultrafine cement, pozzolanic ultrafine cement, fly ash, bentonite, and silica fume according to their mass fractions, pour the materials into a high-speed mixer, and mix them at a speed of 800-1000 rpm for 10-15 minutes to ensure uniformity;

[0035] S202: Add the pretreated microfibers to the high-speed mixer in 2 to 3 batches, with an interval of 5 to 10 minutes between each batch to ensure uniform dispersion;

[0036] Adding microfibers in batches can prevent agglomeration and improve dispersion efficiency.

[0037] S203: Add a waterproofing agent and a water reducing agent to a high-speed mixer and stir for 5 minutes at a speed of 800-1000 rpm to obtain component A material;

[0038] S301: Mix water glass and silica sol in proportion, stir for 2 minutes, and rotate at 300-500 rpm;

[0039] (Be careful to avoid vigorous stirring that may damage the silica sol nanoparticles, 300 rpm is preferred)

[0040] S302: Disperse the anti-salt agent in water, add it to the mixed solution in S301, and stir until dissolved to obtain component B material;

[0041] (It is worth noting that the anti-salt agent needs to be completely dissolved to avoid local overdose. In practical applications, the anti-salt agent can be pre-dissolved in an ethanol-water mixed solvent before adding for better uniformity. The B component material needs to be sealed and stored away from light to avoid prolonged contact with air.)

[0042] S401: slowly adding the component A material obtained in S203 to the component B material obtained in S302, stirring for 5 minutes at a speed of 300-500 rpm to initially form a slurry;

[0043] S402: Slowly pour the component C material obtained in S105 into the slurry obtained in S401, and continue stirring for 10 to 15 minutes at a speed of 300 to 500 rpm to ensure uniform distribution of the microspheres;

[0044] (It is worth noting that component C needs to be added last to avoid premature reaction of the microspheres and protect the activity of the microspheres. In practical applications, a lower shear rate, such as 300 rpm, is preferred to prevent damage to the microspheres.)

[0045] S501: Adjust the water-cement ratio according to the fluidity of the slurry until the slump of the slurry is 180-220 mm to obtain a high-strength, waterproof, closed reinforcement material.

[0046] Control the slump of the grouting material to ensure fluidity. In practical applications, rheology regulators such as bentonite can be used to assist in adjustment.

[0047] Beneficial effects of the present invention:

[0048] 1. By combining environmentally responsive functional microspheres with inorganic reinforcement materials, when applied to water-absorbing rock formations, it can block the path of water loss, reduce water migration, effectively control the water loss rate of grouting materials, and prevent the rock formation from swelling and becoming unstable due to excessive water absorption;

[0049] 2. The water in the slurry is not easily absorbed by the water-absorbing rock formation, which further maintains the stability of the water-cement ratio of the water in the slurry and the solid phase material, avoiding insufficient hydration of cement or cementitious materials due to premature water loss, thereby improving the compressive strength and tensile strength;

[0050] 3. Pre-treatment with microfibers, water glass and silica sol can avoid material agglomeration, improve dispersion and further enhance the workability of grouting materials;

[0051] 4. When the grouting material provided by the present invention is used in combination with an anchor rod, the anchor rod, the rock layer and the grout form a continuous bonding surface, which significantly improves the pull-out resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Shown is a flow chart of the preparation method of the high-strength, invisible, closed reinforcement material of the present invention. DETAILED DESCRIPTION

[0053] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0054] The numerical ranges herein are understood to specifically disclose every intervening value between the upper and lower limits of the range. Each smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in that stated range is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0055] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0056] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0057] All “parts” described in the following examples are “parts by mass”.

[0058] The invention discloses a high-strength, waterproof, closed reinforcement material, which is composed of the following components in parts by mass: component A: 35-45 parts of silicate ultrafine cement, 10-15 parts of pozzolanic ultrafine cement, 10-15 parts of fly ash, 5-10 parts of bentonite, 4-5 parts of silica fume, 0.2-0.5 parts of microfiber, 2-5 parts of waterproofing agent and 0.5-1 part of water reducer; component B: 10-15 parts of water glass, 2-5 parts of silica sol, 0.2-0.5 parts of salt-resistant agent and water; component C: 0.5-1 part of environmentally responsive functional microspheres.

[0059] Simulation experiment material 1: gypsum mixed with bentonite (simulating low permeability rock formation), the material ratio includes 80% gypsum powder + 20% sodium bentonite (simulating the microporous structure of water-absorbing rock formation), the mixture is added with water and stirred into slurry, and cast into a specimen (size: 100×100×100mm 3 ), and used after natural curing for 7 days. The material was immersed in 3% NaCl solution (low salt environment simulation).

[0060] Simulation experiment material 2: bentonite + saline soil (simulating high permeability saline rock formation), the material ratio includes 50% sodium-based bentonite + 50% saline soil (containing 10% NaCl), added with water to form a slurry, cast into a specimen, and used after natural curing for 7 days. The material was soaked in 10% NaCl solution (high salt environment simulation).

[0061] Example 1

[0062] Preparation of high-strength, waterproof, closed reinforcement materials:

[0063] Material formula:

[0064] Component A: 40 parts of silicate ultrafine cement (PO 52.5), 12 parts of pozzolanic cement (P P 42.5), 12 parts of fly ash, 7 parts of sodium bentonite, 4.5 parts of silica fume, 0.3 parts of microfiber (60% polypropylene + 40% steel fiber), 3 parts of waterproofing agent, and 0.7 parts of water reducer.

[0065] Component B: 12 ​​parts of water glass, 3.5 parts of silica sol, 0.2 parts of salt-resistant agent (hydroxymethyl cellulose + calcium silicate);

[0066] Component C: 0.5 parts of sodium alginate microspheres.

[0067] The above material formula is mixed according to the preparation method of high-strength, non-toxic, closed reinforcement material to obtain grouting material 1.

[0068] Experimental steps:

[0069] The surface of the anchor rod (Φ25 mm, L=6 m) was cleaned and installed in alignment with the simulation experimental material 1. Grouting equipment was used to inject the grouting material 1 into the simulation experimental material 1 through the anchor rod at a pressure of 0.3 to 0.5 MPa.

[0070] Experimental test indicators:

[0071] Water loss rate: 5.5-6% one hour after grouting;

[0072] Strength: 28-day compressive strength 56-58MPa, tensile strength 6.5-7MPa;

[0073] Crack resistance: Microscopic observation of crack width ≤ 0.05mm;

[0074] Anchor bond strength: The pull-out test shows that the anchor pull-out strength is ≥ 1.1 times the design value (design value 100kN);

[0075] Rock formation properties: The water absorption rate of the simulated experimental material 1 is 7.8-8%, and the expansion rate is 2.9-3%.

[0076] Example 2

[0077] Preparation of high-strength, waterproof, closed reinforcement materials:

[0078] Material formula:

[0079] Component A: 40 parts of silicate ultrafine cement (PO 52.5), 12 parts of pozzolanic cement (P P 42.5), 12 parts of fly ash, 7 parts of sodium bentonite, 4.5 parts of silica fume, 0.3 parts of microfiber (60% polypropylene + 40% steel fiber), 3 parts of waterproofing agent, and 0.7 parts of water reducer.

[0080] Component B: 12 ​​parts of water glass, 3.5 parts of silica sol, 0.5 parts of salt-resistant agent (hydroxymethyl cellulose + calcium silicate);

[0081] Component C: 1.0 part of sodium alginate microspheres.

[0082] The above material formula is mixed according to the preparation method of high-strength, non-toxic, closed reinforcement material to obtain grouting material 2.

[0083] Experimental steps:

[0084] The surface of the anchor rod (Φ25mm, L=6m) was cleaned and installed in alignment with the simulation experimental material 1. Grouting material 2 was injected into the simulation experimental material 1 through the anchor rod at a pressure of 0.3-0.5MPa using grouting equipment.

[0085] Experimental test indicators:

[0086] Water loss rate: 3-3.6% one hour after grouting;

[0087] Strength: 28-day compressive strength 65-68MPa, tensile strength 8.5-8.7MPa;

[0088] Crack resistance: Microscopic observation of crack width ≤ 0.05mm;

[0089] Anchor bond strength: The pull-out test shows that the anchor pull-out strength is ≥ 1.3 times the design value (design value 100kN);

[0090] Rock formation properties: The water absorption rate of the simulated experimental material 1 is 5-5.4%, and the expansion rate is 1.5-1.6%.

[0091] Example 3

[0092] Preparation of high-strength, waterproof, closed reinforcement materials:

[0093] Material formula:

[0094] Component A: 40 parts of silicate ultrafine cement (PO 52.5), 12 parts of pozzolanic cement (P P 42.5), 12 parts of fly ash, 7 parts of sodium bentonite, 4.5 parts of silica fume, 0.3 parts of microfiber (60% polypropylene + 40% steel fiber), 3 parts of waterproofing agent, and 0.7 parts of water reducer.

[0095] Component B: 12 ​​parts of water glass, 3.5 parts of silica sol, 0.2 parts of salt-resistant agent (acrylamide copolymer + EDTA);

[0096] Component C: 0.5 parts of chitosan microspheres.

[0097] The above material formula is mixed according to the preparation method of high-strength, non-toxic, closed reinforcement material to obtain grouting material 3.

[0098] Experimental steps:

[0099] The surface of the anchor rod (Φ25mm, L=6m) was cleaned and installed in alignment with the simulation experimental material 2. Grouting material 3 was injected into the simulation experimental material 2 through the anchor rod at a pressure of 0.3-0.5MPa using grouting equipment.

[0100] Experimental test indicators:

[0101] Water loss rate: 8.6-9% one hour after grouting;

[0102] Strength: 28-day compressive strength 51-52 MPa, tensile strength 5.5-6.0 MPa;

[0103] Crack resistance: Microscopic observation of crack width ≤ 0.05mm;

[0104] Anchor bond strength: The pull-out test shows that the anchor pull-out strength is ≥ 1.05 times the design value (design value 100kN);

[0105] Rock formation properties: The water absorption rate of the simulated experimental material 2 is 13.6-14%, and the expansion rate is 4.8-5%.

[0106] Example 4

[0107] Preparation of high-strength, waterproof, closed reinforcement materials:

[0108] Material formula:

[0109] Component A: 40 parts of silicate ultrafine cement (PO 52.5), 12 parts of pozzolanic cement (P P 42.5), 12 parts of fly ash, 7 parts of sodium bentonite, 4.5 parts of silica fume, 0.3 parts of microfiber (60% polypropylene + 40% steel fiber), 3 parts of waterproofing agent, and 0.7 parts of water reducer.

[0110] Component B: 12 ​​parts of water glass, 3.5 parts of silica sol, 0.2 parts of anti-salt agent (acrylamide + EDTA);

[0111] Component C: 1.0 part of chitosan microspheres.

[0112] The above material formula is mixed according to the preparation method of high-strength, non-toxic, closed reinforcement material to obtain grouting material 4.

[0113] Experimental steps:

[0114] The surface of the anchor rod (Φ25 mm, L=6 m) was cleaned and installed in alignment with the simulation experimental material 1. Grouting equipment was used to inject the grouting material 4 into the simulation experimental material 2 through the anchor rod at a pressure of 0.3 to 0.5 MPa.

[0115] Experimental test indicators:

[0116] Water loss rate: 5-5.8% one hour after grouting;

[0117] Strength: 28-day compressive strength 60-62MPa, tensile strength 7.5-7.8MPa;

[0118] Crack resistance: Microscopic observation of crack width ≤ 0.05mm;

[0119] Anchor bond strength: The pull-out test shows that the anchor pull-out strength is ≥ 1.20 times the design value (design value 100kN);

[0120] Rock formation properties: The water absorption rate of the simulated experimental material 1 is 10-10.8%, and the expansion rate is 3-3.2%.

[0121] Key experimental performance analysis of each embodiment:

[0122] 1. With reference to Examples 1 and 2, under a low-salt environment:

[0123]

[0124]

[0125] Based on the comparative analysis of Example 1 and Example 2, hydroxymethyl cellulose and calcium silicate form a microporous sealing layer in a low-salt environment, reducing water loss and salt ion penetration, and improving the density of the material. The sodium alginate microspheres swell when exposed to water to form a physical sealing layer, reducing the water loss rate (an average decrease of 2.45%), and adsorbing a small amount of salt in the rock formation through ion exchange, thereby inhibiting expansion (the rock formation expansion rate is halved). The rapid hydration reaction of the sodium alginate microspheres and the synergistic effect of the salt-repellent agent significantly improve the interface stability between the rock formation and the grouting material.

[0126] 2. Referring to Examples 3 and 4, in a high-salt environment:

[0127] index Example 3 Example 4 Average change Water loss rate (%) 8.6～9.0 5.0～5.8 -3.4 Compressive strength (MPa) 51～52 60～62 +9.5 Tensile strength (MPa) 5.5～6.0 7.5～7.8 +1.9 Anchor pullout strength (kN) ≥105 ≥120 +15 Water absorption rate of rock layer (%) 13.6～14.0 10.0～10.8 -3.4 Rock expansion rate (%) 4.8～5.0 3.0～3.2 -1.8

[0128] Based on the comparative analysis of Example 3 and Example 4, acrylamide and EDTA form a chelating protective layer in a high-salt environment, inhibiting the erosion of salt ions on cement hydration and maintaining the strength of the material (compressive strength increased by 9.5%). Chitosan microspheres strengthen the material structure through cross-linking and curing in a high-salt environment, reducing the salt migration path and reducing the water absorption rate of the rock formation (an average decrease of 3.4%). The salt resistance of the chitosan microspheres and the synergistic effect of the salt-repellent agent effectively inhibit the expansion of the rock formation (the expansion rate is reduced by 40%).

[0129] Comparative analysis of the performance of traditional grouting materials and the grouting materials of the present invention:

[0130]

[0131]

[0132] Traditional cement-based slurry: high water loss rate (10% to 15%). The slurry loses water rapidly during the grouting process, resulting in premature solidification, inability to fully fill the pores in the rock formation, forming voids, reducing density, and rapid fluidity decay. It is difficult to penetrate deeply into complex rock structures, and weak areas are prone to exist at the interface between the anchor rod and the rock formation; the rock formation has a high water absorption rate (10% to 18%). After the slurry solidifies, the rock formation can still absorb a large amount of water, resulting in increased expansion pressure, causing structural instability, poor expansion inhibition, and salt (even at low concentrations) will aggravate the expansion of the rock formation (such as bentonite), which traditional cement cannot effectively block.

[0133] The high-strength, waterproof, closed reinforcement material provided by the present invention has a rock formation water absorption rate of only 5.0-5.4% (1 / 3 of traditional cement-based slurry) and an expansion rate of 1.5-1.6% (1 / 3 of traditional materials) in a low-salt environment. The rock formation water absorption rate in a high-salt environment is 10-10.8% (55% of traditional cement-based slurry) and the expansion rate is 3.0-3.2% (60% of traditional materials). Moreover, the synergistic effect of the environmentally responsive functional microspheres and the salt-resistant agent can still maintain the material strength in a high-salt environment (such as the compressive strength of 60-62 MPa in Example 4 vs. 40-50 MPa of traditional cement-based slurry), avoiding anchor failure caused by expansion. The present invention systematically solves the core problem of grouting reinforcement of water-absorbing rock formations through the synergistic effect of environmentally responsive functional microspheres, salt-resistant agents and refined pretreatment process. Its technical effect is significantly superior to traditional materials in terms of water loss control, expansion inhibition, mechanical properties, environmental adaptability and cost-effectiveness, providing a safer, more efficient and economical solution for tunnel engineering.

[0134] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A high-strength, invisible, closed reinforcement material, characterized in that: It is composed of the following ingredients in parts by mass: Component A: 35-45 parts of silicate ultrafine cement, 10-15 parts of pozzolanic ultrafine cement, 10-15 parts of fly ash, 5-10 parts of bentonite, 4-5 parts of silica fume, 0.2-0.5 parts of microfiber, 2-5 parts of waterproofing agent and 0.5-1 part of water reducing agent; Component B: 10-15 parts of water glass, 2-5 parts of silica sol, 0.2-0.5 parts of anti-salt agent, and water; Component C: 0.5 to 1 part of environmentally responsive functional microspheres.

2. The high-strength, invisible, sealing reinforcement material according to claim 1, characterized in that: The silicate ultrafine cement is P·O 52.5 grade cement, the pozzolanic ultrafine cement is P·P 42.5 grade cement, and the fly ash loss on ignition is ≤8%.

3. The high-strength, invisible, sealing reinforcement material according to claim 1, characterized in that: The bentonite is sodium bentonite, the montmorillonite content is ≥80%, and the CEC is 70-100meq / 100g.

4. The high-strength, waterproof, sealing reinforcement material according to claim 1, characterized in that: The silica content of silica fume is ≥85%, and the specific surface area is ≥17000cm 2 / g, water content ≤3%.

5. The high-strength, waterproof, sealing reinforcement material according to claim 1, characterized in that: The microfiber is a composite fiber composed of polypropylene fiber and steel fiber, wherein the polypropylene fiber accounts for 60% to 70% of the total microfiber content, and the steel fiber accounts for 30% to 40% of the total microfiber content.

6. The high-strength, invisible, sealing reinforcement material according to claim 1, characterized in that: The waterproofing agent is a cement-based penetrating crystallization waterproofing agent, and the water reducer is a polycarboxylic acid water reducer.

7. The high-strength, invisible, sealing reinforcement material according to claim 1, characterized in that: The water glass modulus is 2.0 to 3.5, the density is 40 to 42°Bé, the silica sol particle size is 10 to 20 nanometers, the pH value is 7 to 9, and the solid content is 25% to 30%.

8. The high-strength, invisible, sealing reinforcement material according to claim 1, characterized in that: The environmentally responsive functional microspheres are sodium alginate microspheres, and the anti-salt agents are hydroxymethyl cellulose and calcium silicate.

9. The high-strength, invisible, sealing reinforcement material according to claim 1, characterized in that: The environmentally responsive functional microspheres are chitosan composite microspheres, and the salt-resistant agents are acrylamide copolymer and EDTA.

10. A method for preparing a high-strength, invisible, closed reinforcement material, characterized in that: The method for preparing the high-strength, waterproof, closed reinforcement material as claimed in claim 1 comprises the following steps: S101: pre-treating the water glass, including adding EDTA chelating agent at a rate of 0.05% to 0.1% of the mass of the water glass, stirring for 10 to 15 minutes, standing and filtering, and storing the water glass solution at room temperature; S102: pre-treating the silica sol, including adding activated carbon at a rate of 0.2% to 0.5% of the mass of the silica sol, stirring for 30 minutes, filtering, reserving the silica sol solution, and adding a small amount of NaOH or citric acid to adjust the pH value of the silica sol to a range of 7 to 9; S103: Pre-treating the bentonite, including mixing the bentonite with water and stirring for 30 minutes to form a uniform slurry for later use; S104: Pre-treating the microfibers, including wetting the surface with an active agent or spraying water; S105: Selecting appropriate environmentally responsive functional microspheres according to the salinity of the water-absorbing rock formation and pre-treating the environmentally responsive functional microspheres, including dispersing the microspheres in water, adding a silane coupling agent, and stirring at a speed of 50-150 rpm until the microspheres are completely dispersed without agglomeration, thereby obtaining component C material; S201: Weigh silicate ultrafine cement, pozzolanic ultrafine cement, fly ash, bentonite, and silica fume according to their mass fractions, pour the materials into a high-speed mixer, and mix them at a speed of 800-1000 rpm for 10-15 minutes to ensure uniformity; S202: Add the pretreated microfibers to the high-speed mixer in 2 to 3 batches, with an interval of 5 to 10 minutes between each batch to ensure uniform dispersion; S203: Add a waterproofing agent and a water reducing agent to a high-speed mixer and stir for 5 minutes at a speed of 800-1000 rpm to obtain component A material; S301: Mix water glass and silica sol in proportion and stir for 2 minutes at a speed of 300-500 rpm; S302: Disperse the anti-salt agent in water, add it to the mixed solution in S301, and stir until dissolved to obtain component B material; S401: slowly adding the component A material obtained in S203 to the component B material obtained in S302, stirring for 5 minutes at a speed of 300-500 rpm to initially form a slurry; S402: slowly pour the component C material obtained in S105 into the slurry obtained in S401, and continue stirring for 10 to 15 minutes at a speed of 300 to 500 rpm to ensure uniform distribution of the microspheres; S501: Adjust the water-cement ratio according to the fluidity of the slurry until the slump of the slurry is 180-220 mm to obtain a high-strength, waterproof, closed reinforcement material.

Images