Capillary crystallization type grouting material as well as preparation method and application thereof

Abstract

The invention provides a capillary crystalline grouting material as well as a preparation method and application thereof, and belongs to the technical field of tunnel engineering grouting materials. The components comprise ordinary Portland cement, XYPEX, nano SiO2, a polycarboxylate superplasticizer and water; the method comprises the following steps: uniformly mixing Portland cement and XYPEX to obtain a master batch; the preparation method comprises the following steps: adding nano SiO2 into water, uniformly stirring, stirring at a high speed by using a glass rod, and dispersing by using ultrasonic waves to obtain a solution A; adding the polycarboxylate superplasticizer into the residual water, and uniformly mixing to obtain a solution B; and mixing the solution A and the solution B with the master batch in three times to prepare the capillary crystalline grouting material. The capillary crystalline grouting material is subjected to numerical simulation, a heat-fluid-solid coupling model is established, the influence rule of the porosity, the hydraulic gradient and the environment temperature on the capillary crystalline grouting material is analyzed, and the application scene of the capillary crystalline grouting material is determined. The problems that in the prior art, impermeability is insufficient, durability is poor, environment friendliness is not achieved, and adaptability to complex working conditions is poor are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering grouting materials, in particular to a permeable crystallization grouting material and a preparation method and application thereof. Background Art

[0002] In shield tunnel construction, grouting behind the lining is the main step in ensuring structural stability and waterproof performance. Currently, the commonly used traditional grouting materials mainly include cement-based slurry, water glass slurry and chemical slurry. Among them, although cement-based slurry is economical and durable, its anti-permeability is limited and it is prone to leakage in water-rich or high-water-pressure strata; water glass slurry sets quickly, but shrinks significantly after hardening, and its structural stability is insufficient under long-term service; although chemical slurry has excellent fluidity, most of it contains harmful chemical components, which may cause environmental pollution during construction, and its long-term mechanical properties decay significantly. In addition, traditional materials generally have poor adaptability to complex geological conditions. For example, in sand layers with high permeability coefficients or strata with developed fractures, slurry is prone to loss and it is difficult to form an effective consolidation body, resulting in a significant increase in the risk of water leakage in the later stages of the tunnel.

[0003] However, the emergence of cement-based permeable crystalline waterproofing materials (CCCW) has provided a new approach to solving the above problems. With its self-healing ability and environmentally friendly properties, it has shown potential in the field of tunnel waterproofing. However, there are still key technical bottlenecks when using CCCW alone: on the one hand, it lacks nano-scale filling components, making it difficult to effectively reduce the porosity of the consolidated body, resulting in limited improvement in strength and impermeability; on the other hand, existing technologies have insufficient research on the synergistic mechanism between nanomaterials and CCCW, making it impossible to achieve performance optimization through material compounding. In addition, the design of traditional grouting materials relies on empirical trial mixing and lacks quantitative analysis of multi-physical field coupling conditions. For example, the influence of parameters such as porosity, hydraulic gradient, and ambient temperature on material properties has not been systematically studied, resulting in the inability to accurately predict the applicability of materials under different geological and climatic conditions through scientific models. The definition of engineering application scenarios relies on subjective judgment, and construction risk control lacks a theoretical basis.

[0004] Therefore, in order to effectively prevent and control water leakage disasters in tunnel projects, there is an urgent need for a grouting material with excellent strength, excellent impermeability, simple preparation process and environmental friendliness to solve the technical bottlenecks of traditional materials under complex working conditions and improve the reliability and sustainability of tunnel projects. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a permeable crystallization grouting material and its preparation method and application. The obtained grouting material has the characteristics of excellent strength, excellent impermeability, simple preparation process and environmental friendliness, and accurately determines its application scenarios in tunnel synchronous grouting projects, solving the problems of insufficient impermeability, poor durability, environmental unfriendliness and poor adaptability to complex working conditions of traditional grouting materials.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A permeable crystallization grouting material, the permeable crystallization grouting material is composed of the following components:

[0008] Ordinary Portland cement;

[0009] XYPEX, the mass of which is 2.0% to 4.0% of the ordinary Portland cement;

[0010] Nano-SiO2, the mass of which is 0.5% to 1.5% of the ordinary Portland cement;

[0011] Polycarboxylate high-efficiency water reducer, the mass of which is 0.25% to 0.35% of the ordinary Portland cement;

[0012] Water, wherein the mass ratio of water to ordinary Portland cement is 0.35-0.45:1.0.

[0013] Preferably, the ordinary Portland cement is of PO 42.5 grade, accounting for 80% to 90% of the permeable crystallization grouting material.

[0014] The present invention also provides a method for preparing the above-mentioned infiltration crystallization grouting material, comprising the following steps:

[0015] S1. Mix ordinary Portland cement and XYPEX in proportion to obtain a masterbatch;

[0016] S2, adding nano-SiO2 to 50% water and stirring, stirring with a glass rod and then ultrasonically dispersing to obtain solution A;

[0017] S3, adding polycarboxylate superplasticizer to the remaining water and stirring evenly to obtain solution B;

[0018] S4. Mixing the solution A and the solution B with the masterbatch three times, stirring for 5 minutes after each mixing, to obtain the infiltration crystallization grouting material.

[0019] Preferably, in S1, the stirring rate of the ordinary Portland cement and XYPEX after mixing is 70-100 rpm, and the stirring time is 2-5 min.

[0020] Preferably, in S2, the ultrasonic dispersion time is 10 to 15 minutes.

[0021] Preferably, in S3, the stirring time after the polycarboxylate high-efficiency water reducer is added to the remaining water is 5 to 10 minutes.

[0022] The present invention also provides an application of the above-mentioned permeable crystallization grouting material, which is applied to tunnel synchronous grouting projects. A thermal-fluid-solid coupling model is established through COMSOL numerical simulation to analyze the influence of porosity, hydraulic gradient, and temperature on the material and determine the application scenario.

[0023] Preferably, a thermal-fluid-solid coupling model is established by COMSOL numerical simulation software, the influence of porosity on the permeable crystallization grouting material is analyzed, and the accurate characterization of the model is determined; wherein the porosity is set to 10%, 15%, 20%, 25%, 30%, and 35%, and the porosity decrease values of 10%, 43%, and 63% correspond to single doping of 3% XYPEX, single doping of 1% nano-SiO2, and combined doping of 3% XYPEX and 1% nano-SiO2, respectively.

[0024] Preferably, a thermal-fluid-solid coupling model is established by COMSOL numerical simulation software to analyze the influence of hydraulic gradient on the permeable crystallization grouting material and determine the geological environment of the grouting material; wherein the hydraulic gradient is divided into:

[0025] Low hydraulic gradient levels I to VI: 0.1%, 0.15%, 0.3%, 0.5%, 0.7%, 0.9%;

[0026] Medium hydraulic gradient levels I to VI: 1%, 1.5%, 3%, 5%, 7%, 9%;

[0027] High hydraulic gradient levels I to VI: 15%, 30%, 50%, 70%, 90%.

[0028] Preferably, a thermal-fluid-solid coupling model is established by COMSOL numerical simulation software to analyze the effect of temperature on the infiltration crystallization grouting material and determine the temperature environment of the grouting material; wherein the temperature is set to:

[0029] Low temperature level I to VI: -20℃, -15℃, -10℃, -5℃, 0℃, 5℃;

[0030] Normal temperature levels I to VI: 10°C, 14°C, 18°C, 22°C, 26°C, 29°C;

[0031] High temperature levels I to VI: 30℃, 35℃, 40℃, 45℃, 50℃, 55℃.

[0032] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0033] The present invention adopts water and silicate cement in a mass ratio of (0.35-0.45):1.0, and utilizes the characteristics of silicate cement such as good durability, high strength and non-toxicity to achieve economical, practical and environmentally friendly effects; by adding 0.25% to 0.35% of polycarboxylic acid high-efficiency water-reducing agent to the silicate cement, the negative charge of the molecular chain causes the cement particles to repel, disperse the particles to reduce agglomeration, and improve the fluidity of the slurry; by adding 0.5% to 1.5% of nano-SiO2 to the silicate cement, the pore filling structure and crystal nucleation effect, the pozzolanic properties and the Ca( OH)2 reaction, reducing the accumulation of Ca(OH)2 in the interface transition zone, and enhancing the density and strength of the grouting material; by adding 2.0% to 4.0% of XYPEX to silicate cement, its active substances undergo condensation crystallization reaction in a humid environment to generate crystals to fill pores and cracks, and through the catalysis-complexation-precipitation reaction mechanism, insoluble crystals and CSH gel are generated to fill the pores, thereby improving the density, strength and impermeability of the material; by conducting a series of slurry basic performance tests, the slurry performance parameters when different raw material addition amounts are determined to meet different engineering conditions and requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a flow chart of a method for preparing a permeable crystallization grouting material according to the present invention;

[0036] Figure 2 This is the SEM test result diagram of the grouting material provided by the present invention under the curing condition of 28 days; wherein, Figure 2 (a) is the SEM test result of 5μm and 2μm cement paste (WP) samples under the condition of curing for 28 days; Figure 2 (b) is the SEM test result of the 5μm and 2μm samples with the best ratio (Z1) under the curing condition of 28 days; Figure 2 (c) is the SEM test result of single-doped nano-silica (X0) 5μm and 2μm samples under the condition of curing for 28 days; Figure 2 (d) is the SEM test result of 5μm and 2μm samples of single-doped XYPEX (N0) under the condition of curing for 28 days;

[0037] Figure 3Schematic diagram of mesh division of COMSOL numerical simulation geometric model provided by the present invention;

[0038] Figure 4 The Darcy velocity cross-sectional distribution diagram under different initial porosity conditions provided by the present invention; wherein, Figure 4 (a) is the Darcy velocity cross-section distribution diagram at an initial porosity of 10%. Figure 4 (b) is the Darcy velocity cross-section distribution diagram at an initial porosity of 15%. Figure 4 (c) is the Darcy velocity cross-section distribution diagram at an initial porosity of 20%. Figure 4 (d) is the Darcy velocity cross-section distribution diagram at an initial porosity of 25%. Figure 4 (e) is the Darcy velocity cross-section distribution diagram at an initial porosity of 30%. Figure 4 (f) in the figure is the Darcy velocity cross-section distribution diagram at an initial porosity of 35%. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 As shown, the present invention provides a method for preparing a permeable crystallization grouting material, comprising the following steps:

[0042] S1. Mix ordinary Portland cement and XYPEX in proportion to obtain a masterbatch;

[0043] The stirring rate of the ordinary Portland cement and XYPEX after mixing is 70-100 rpm, and the stirring time is 2-5 minutes.

[0044] S2, adding nano-SiO2 to 50% water and stirring, stirring with a glass rod and then ultrasonically dispersing to obtain solution A;

[0045] Wherein, the ultrasonic dispersion time is 10 to 15 minutes.

[0046] S3, adding polycarboxylate superplasticizer to the remaining water and stirring evenly to obtain solution B;

[0047] The stirring time after the polycarboxylate high-efficiency water reducer is added to the remaining water is 5 to 10 minutes.

[0048] S4. Mixing the solution A and the solution B with the masterbatch three times, stirring for 5 minutes after each mixing, to obtain the infiltration crystallization grouting material.

[0049] According to the above content, the infiltration crystallization grouting material consists of the following components:

[0050] Ordinary Portland cement; the ordinary Portland cement is of PO 42.5 grade, accounting for 80% to 90% of the permeable crystallization grouting material.

[0051] XYPEX is a permeable crystalline waterproofing material, which is added at a rate of 2.0% to 4.0% of Portland cement. It contains a variety of active substances, such as the active substance (Ca(OR-OH)2), which undergoes a polycondensation and crystallization reaction in a humid environment to form water-insoluble crystals [OR]. 2n , which can fill the pores and cracks in the solid body, making the solid body structure more compact; at the same time, after the silicate cement is hydrated, a large amount of Ca 2+ , Ca(OH)2, dicalcium silicate (C2S) and tricalcium silicate (C3S) and other substances. The active substances in XYPEX will enter the pores of the consolidated body through the effects of osmotic pressure, capillary pressure and concentration difference and react with Ca in the pore solution. 2+ , Ca(OH)2, C2S and C3S react to form water-insoluble needle-shaped ettringite (AFt) and calcium silicate hydrate (CSH) gel to fill the pores.

[0052] Further, refer to Figure 2 In (a), (b), (c) and (d), XYPEX active substances can play a catalytic-complexation-precipitation reaction mechanism, catalytic acceleration: some active substances provide CO3 2- and SiO3 2- The components can react with cement hydration products CH, C2 S It reacts chemically with C3S to form some insoluble crystals, such as CS-gel, CaSiO3 and CaCO3. The crystals generated by these reactions help to improve the density and stability of cement-based materials. However, other active substances do not directly participate in the formation of these crystals, but promote further reactions between unhydrated cement particles and existing hydration products through catalysis to generate more CSH gel. Ultimately, the CSH gel generated by these reactions fills the pores and cracks, thereby reducing the porosity and significantly improving the strength and overall stability of the material. In the cement system, the active substances can react with the Ca in the cement system.2+ Forming complexes. When these complexes come into contact with water, further chemical reactions will occur. When the complexes react with CO3 in water 2- and SiO3 2- When the ions meet, these anions will react with the Ca 2+ Competitive effects occur, ultimately leading to Ca 2+ By this process, the active substances not only help to regulate the Ca content in cement, but also 2+ The distribution of cement can also promote the formation of sediments, which help to enhance the density of cement-based materials and further improve their stability and durability.

[0053] Furthermore, the active substance has the ability to undergo polycondensation reaction and can self-polymerize to form [OR] 2n Type crystals, the reaction formula is as follows:

[0054] 2nCa(OR-OH)2→2[OR] 2n +2nCa(OH)2

[0055] In the absence of moisture, the active substances remain dormant and inactive. However, upon contact with water, they are reactivated, using water molecules as carriers to continue penetrating and diffusing into the cementitious material. Once inside the cementitious material, the active substances interact with cement particles or cement hydration products, continuing to catalyze reactions, promoting complexation reactions and forming precipitated crystals. This recurring crystallization process ensures the continued strengthening effect of the cementitious material.

[0056] Nano-SiO2 is a highly effective nanomaterial, with an incorporation rate of 0.5% to 1.5% of Portland cement. Nano-SiO2 not only effectively reduces or partially fills the pore structure within the composite slurry, but also exhibits a unique nucleation effect and pozzolanic properties, reacting chemically with the Ca(OH)2 produced during cement hydration. This reduces Ca(OH)2 accumulation in the interface transition zone, thereby enhancing the density of the grouting material. Nano-SiO2 primarily serves as a filler in permeable crystallization grouting materials.

[0057] Polycarboxylic acid high-efficiency water-reducing agent is a beige powdery substance, and its addition mass is 0.25% to 0.35% of silicate cement. The molecular chain of polycarboxylic acid high-efficiency water-reducing agent carries a large amount of negative charge. These negative charges can produce a strong repulsive effect on the surface of cement particles, thereby effectively dispersing cement particles, reducing coagulation and agglomeration between particles, and thus improving the fluidity of the slurry.

[0058] Water, wherein the mass ratio of water to ordinary Portland cement is 0.35-0.45:1.0.

[0059] The following experiments were conducted with nano-SiO2 (NS) at 0.5%, 1%, and 1.5% of the Portland cement mass; XYPEX at 2%, 3%, and 4% of the Portland cement mass; and polycarboxylate superplasticizer (PCS) at 0.25%, 0.3%, and 0.35% of the Portland cement mass. Water-cement ratios were selected at 0.3, 0.4, and 0.45.

[0060] First, the viscosity of the slurry of the infiltrative crystallization grouting material provided by the present invention was measured. The infiltrative crystallization slurry was prepared into slurries of different proportions, and the viscosity of the slurry was measured with reference to JJG1002-2005, "Verification Procedure for Rotational Viscometers." An NDJ-8S digital rotational viscometer was used, with rotor No. 1 selected and the speed controlled at 6 r / min. After turning on the power, the needle reading was allowed to stabilize, and the data was recorded. The specific slurry viscosity values are shown in Table 1.

[0061] Table 1 Slurry viscosity measurement results

[0062]

[0063] It can be seen from Table 1 that the order of influence of slurry viscosity is: NS dosage > XYPEX dosage > water-cement ratio > PCS dosage.

[0064] Secondly, the slurry setting time of the permeable crystallization grouting material provided by the present invention was measured. The permeable crystallization slurry was prepared into slurries of different proportions, and the initial setting time and final setting time of the slurry were measured with reference to GB / T1346-2001 "Test Method for Water Consumption, Setting Time and Stability of Cement Standard Consistency". The setting time is determined by the depth of the Vicat test needle inserted into the slurry volume. The initial setting time is the time required for the initial setting test needle to sink to 4±1mm from the bottom plate; the final setting time is the time required when the final setting test needle sinks to 0.5mm from the slurry surface and cannot leave a mark on the specimen. The specific slurry setting time is shown in Table 2.

[0065] Table 2 Slurry coagulation time measurement results

[0066]

[0067] As shown in Table 2, the order of influence on the initial setting time of the slurry is: NS dosage > XYPEX dosage > water-cement ratio > PCS dosage. The order of influence on the final setting time of the slurry is: NS dosage > XYPEX dosage > PCS dosage > water-cement ratio.

[0068] Next, the compressive strength of the slurry-consolidated form of the permeable crystallization grouting material provided by the present invention was measured. The permeable crystallization slurry was prepared into slurries with different proportions. The compressive strength of the slurry-consolidated forms after standard curing for 3 days, 7 days, and 28 days was measured with reference to GB / T 50081-2002, "Standard for Test Methods for Mechanical Properties of Ordinary Concrete." The specimens were sized 70.7 mm × 70.7 mm × 70.7 mm. After reaching the specified age, the specimens were loaded at a rate of 0.3 MPa / s on a TAW2000 universal testing machine, and the ultimate failure load was recorded. The compressive strength of the slurry-consolidated forms is shown in Table 3.

[0069] Table 3 Compressive strength test results of slurry consolidation body

[0070]

[0071] Table 3 shows that the order of influence on the compressive strength of the infiltrated crystallization slurry consolidation after 3 days of curing is: NS content > XYPEX content > water-cement ratio > PCS content. The order of influence on the compressive strength of the infiltrated crystallization slurry consolidation after 7 days of curing is: NS content > PCS content > XYPEX content > water-cement ratio. The order of influence on the compressive strength of the infiltrated crystallization slurry consolidation after 28 days of curing is: XYPEX content > NS content > PCS content > water-cement ratio.

[0072] Finally, the relative permeability coefficient of the slurry consolidation of the permeable crystallization grouting material of the present invention was measured. The permeable crystallization slurry was prepared into slurries of different proportions. The relative permeability coefficients of the slurry consolidation after 3 days, 7 days, and 28 days of standard curing were measured with reference to JGJ / T70-2009, "Standard for Test Methods for Basic Properties of Building Mortar." The specimens were sized 70 mm × 80 mm × 30 mm. Each group of six specimens was placed on an SS-15 mortar permeameter after reaching the required age. The specimens were loaded at a rate of 0.1 MPa / h. When three of the six mortar specimens began to seep water, the test was stopped and the water pressure at that time was recorded. The relative permeability coefficient of the slurry consolidation was calculated according to the formula provided below. The specific results are shown in Table 4.

[0073]

[0074] Where K r is the relative permeability coefficient, in cm / s; D m is the average water seepage height of the specimen, in cm; H is the water pressure, expressed as the height of the water column, in cm, 1MPa water pressure is expressed as 10200cm; t is the constant pressure time, in s; a is generally taken as 0.03.

[0075] Table 4 Relative permeability coefficient measurement results of slurry solidification body

[0076]

[0077] Table 4 shows that the order of influence on the relative permeability coefficient of the permeable crystallization slurry consolidation after 3 days of curing is: NS dosage > water-cement ratio > XYPEX dosage > PCS dosage. The order of influence on the relative permeability coefficient of the permeable crystallization slurry consolidation after 7 days of curing is: NS dosage > XYPEX dosage > PCS dosage > water-cement ratio. The order of influence on the relative permeability coefficient of the permeable crystallization slurry consolidation after 28 days of curing is: XYPEX dosage > PCS dosage > water-cement ratio > NS dosage.

[0078] According to Tables 1 to 4 above, the optimal basic formula combination is determined as: water-cement ratio of 0.4, XYPEX content of 3wt%, NS content of 1wt%, and PCS content of 0.3wt%.

[0079] Further, refer to Figure 3 and Figure 4 ,The thermal-fluid-solid coupling model was established by COMSOL numerical simulation software, and the influence of porosity on the infiltration crystallization grouting material was analyzed, and the accurate characterization of the model was determined. The porosity was set to: 10%, 15%, 20%, 25%, 30% and 35%, corresponding to Figure 4 (a), (b), (c), (d), (e) and (f); the porosity reduction is set to 10%, 43% and 63%, corresponding to single doping with 3% XYPEX, single doping with 1% nano-SiO2 and combined doping with 3% XYPEX and 1% nano-SiO2, respectively. The viscosity and density of water are set to standard values, with a viscosity of 1×10 -3 Ps·s, density is 1000kg / m 3 The results are shown in Table 5.

[0080] Table 5 Average Darcy velocity under different porosity conditions

[0081]

[0082] As shown in Table 5, the initial porosity is 15% when the water-cement ratio is 0.4 and the polycarboxylate superplasticizer is 0.3%. The porosity decreases by 10%, 43% and 63% respectively when the XYPEX is added alone at 3%, the nano-SiO2 is added alone at 1% and the composite of XYPEX and nano-SiO2 is added at 3%. The average Darcy velocities of the three are: 14.5×10 -12 m / s, 2.7×10 -12 m / s, 2.2×10 - 12 m / s and 1.4×10 -12m / s, and the 28-day test data was 14.8×10 -12 m / s, 2.71×10 -12 m / s, 2.17×10 -12 m / s and 1.39×10 -12 m / s. By comparison, it was found that its error was between 0% and 3%, and the error rate was below 5%. This shows that the thermal-fluid-solid coupling model established by COMSOL numerical simulation software is accurate.

[0083] Furthermore, when the initial porosity reaches approximately 15%, the average Darcy velocity suddenly increases significantly. This phenomenon reveals that the effect of initial porosity on the Darcy velocity is not linear, but rather exhibits a threshold effect. When the porosity exceeds this critical value, the flow rate becomes more sensitive, indicating that the material's permeability undergoes a significant change at this stage.

[0084] Furthermore, to analyze the effect of hydraulic gradient on permeable crystallization grouting materials, the geological environment of the grouting materials was determined. The hydraulic gradient was set as low, medium, and high. The low hydraulic gradient was set in ascending order (I-VI): 0.1%, 0.15%, 0.3%, 0.5%, 0.7%, and 0.9%; the medium hydraulic gradient was also set in ascending order (I-VI): 1%, 1.5%, 3%, 5%, 7%, and 9%; and the high hydraulic gradient was set in ascending order (I-VI): 15%, 30%, 50%, 70%, and 90%. The results are shown in Table 6.

[0085] Table 6 Mean Darcy velocity under different hydraulic gradient conditions

[0086]

[0087] As can be seen from Table 6, under high hydraulic gradient conditions, the average value of the Darcy velocity is significantly higher than that under low and medium hydraulic gradient conditions, indicating that the permeable crystallization grouting material performs better under low and medium hydraulic gradient conditions. The reason is that under low and medium hydraulic gradient conditions, the flow rate of the fluid is relatively slow, which provides sufficient time for the chemical reaction of the crystallization material, allowing the crystallization product to fully fill the pore structure inside the material; in contrast, under high hydraulic gradient conditions, the rapid flow of the fluid results in insufficient crystallization reaction time, and the crystallization product cannot fully fill the pores, thereby reducing the material's anti-seepage effect. Therefore, from a practical application perspective, the permeable crystallization grouting material is more suitable for use in low or medium hydraulic gradient scenarios to ensure that its anti-seepage performance is fully utilized.

[0088] Furthermore, to analyze the effect of temperature on the permeable crystallization grouting material, the temperature environment of the grouting material was determined. The temperature settings were low, room temperature, and high temperature. The low temperature settings (I to VI) were as follows: -20°C, -15°C, -10°C, -5°C, 0°C, and 5°C; the room temperature settings (I to VI) were as follows: 10°C, 14°C, 18°C, 22°C, 26°C, and 29°C; and the high temperature settings (I to VI) were as follows: 30°C, 35°C, 40°C, 45°C, 50°C, and 55°C. The results are shown in Table 7.

[0089] Table 7 Average Darcy velocity under different temperature conditions

[0090]

[0091] As can be seen from Table 7, under room temperature conditions, the average value of the Darcy velocity is significantly lower than that in low and high temperature environments. The main reason is that under low temperature conditions, the chemical reaction rate slows down, resulting in slow formation of crystallization products, which makes it difficult to fully fill the pores. In addition, the flexibility of the material decreases under low temperature environments, and microcracks are easily generated, which increases the penetration path and thus reduces the impermeability; under high temperature conditions, the crystallization reaction rate accelerates. Although this is conducive to the formation of crystallization products, its excessively fast crystallization process will lead to uneven distribution of crystallization products, thereby generating stress concentration inside the material. Therefore, from the perspective of practical application, infiltration crystallization grouting materials are more suitable for use in room temperature environments to ensure that their impermeability performance is fully utilized.

[0092] Therefore, by using the above-mentioned permeable crystallization grouting material and its preparation method and application, the obtained grouting material has the characteristics of excellent strength, excellent impermeability, simple preparation process and environmental friendliness, and accurately determines its application scenarios in tunnel synchronous grouting projects, solving the problems of insufficient impermeability, poor durability, environmental unfriendliness and poor adaptability to complex working conditions of traditional grouting materials.

[0093] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A permeable crystallization grouting material, characterized in that: The infiltration crystallization grouting material is composed of the following components: Ordinary Portland cement; XYPEX, the mass of which is 2.0% to 4.0% of the ordinary Portland cement; Nano-SiO2, the mass of which is 0.5% to 1.5% of the ordinary Portland cement; Polycarboxylate high-efficiency water reducer, the mass of which is 0.25% to 0.35% of the ordinary Portland cement; Water, wherein the mass ratio of water to ordinary Portland cement is 0.35-0.45:1.

0.

2. A permeation crystallization grouting material according to claim 1, characterized in that: The ordinary Portland cement is of PO 42.5 grade and accounts for 80% to 90% of the permeable crystallization grouting material.

3. A method for preparing the infiltration crystallization grouting material according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Mix ordinary Portland cement and XYPEX in proportion to obtain a masterbatch; S2, adding nano-SiO2 to 50% water and stirring, stirring with a glass rod and then ultrasonically dispersing to obtain solution A; S3, adding polycarboxylate superplasticizer to the remaining water and stirring evenly to obtain solution B; S4. Mixing the solution A and the solution B with the masterbatch three times, stirring for 5 minutes after each mixing, to obtain the infiltration crystallization grouting material.

4. The method for preparing a permeable crystallization grouting material according to claim 3, wherein: In S1, the stirring rate of the ordinary Portland cement and XYPEX after mixing is 70-100 rpm, and the stirring time is 2-5 minutes.

5. The method for preparing a permeable crystallization grouting material according to claim 3, wherein: In S2, the ultrasonic dispersion time is 10 to 15 minutes.

6. The method for preparing a permeable crystallization grouting material according to claim 3, wherein: In S3, the stirring time after the polycarboxylate high-efficiency water reducer is added to the remaining water is 5 to 10 minutes.

7. A use of the infiltration crystallization grouting material according to any one of claims 1 to 2, characterized in that: The permeable crystallization grouting material is used in tunnel synchronous grouting projects. A thermal-fluid-solid coupling model is established through COMSOL numerical simulation to analyze the influence of porosity, hydraulic gradient, and temperature on the material and determine the application scenario.

8. The use of a permeation crystallization grouting material according to claim 7, characterized in that: A thermal-fluid-solid coupling model was established using COMSOL numerical simulation software to analyze the effect of porosity on the permeable crystallization grouting material and determine the accurate characterization of the model; wherein the porosity was set to 10%, 15%, 20%, 25%, 30%, and 35%, and the porosity decrease values of 10%, 43%, and 63% corresponded to single doping with 3% XYPEX, single doping with 1% nano-SiO2, and combined doping with 3% XYPEX and 1% nano-SiO2, respectively.

9. The use of a permeation crystallization grouting material according to claim 7, characterized in that: The thermal-fluid-solid coupling model was established by COMSOL numerical simulation software to analyze the influence of hydraulic gradient on the permeable crystallization grouting material and determine the geological environment of the grouting material; wherein the hydraulic gradient is divided into: Low hydraulic gradient levels I to VI: 0.1%, 0.15%, 0.3%, 0.5%, 0.7%, 0.9%; Medium hydraulic gradient levels I to VI: 1%, 1.5%, 3%, 5%, 7%, 9%; High hydraulic gradient levels I to VI: 15%, 30%, 50%, 70%, 90%.

10. The use of a permeation crystallization grouting material according to claim 7, characterized in that: A thermal-fluid-solid coupling model was established using COMSOL numerical simulation software to analyze the effect of temperature on the infiltration crystallization grouting material and determine the temperature environment of the grouting material; wherein the temperature is set to: Low temperature level I to VI: -20℃, -15℃, -10℃, -5℃, 0℃, 5℃; Normal temperature levels I to VI: 10°C, 14°C, 18°C, 22°C, 26°C, 29°C; High temperature levels I to VI: 30℃, 35℃, 40℃, 45℃, 50℃, 55℃.

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