High-flow-state grouting material suitable for water-rich stratum and preparation method of high-flow-state grouting material

Abstract

The invention relates to a high-flow-state grouting material suitable for a water-rich stratum and a preparation method, and the high-flow-state grouting material is prepared from the following components in parts by weight: 16 to 24 parts of Portland cement, 24 to 36 parts of fly ash, 42 to 58 parts of fine sand, 0.08 to 0.17 part of polyacrylamide, 0.15 to 0.3 part of viscosity-reducing polycarboxylic acid water reducing agent, 0.16 to 0.33 part of hydroxypropyl methyl cellulose, 3.2 to 4.5 parts of light magnesium oxide and 1 to 2.5 parts of calcium formate. With the adoption of the grouting material and the preparation method disclosed by the invention, the requirements of giving consideration to both pumping fluidity and anti-scouring performance are met.

Description

Technical Field

[0001] This invention relates to the field of underground engineering technology, specifically to a high-fluidity grouting material and its preparation method suitable for water-rich strata. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Synchronous grouting is a necessary step in shield tunneling. As the geological environment of tunnel projects becomes increasingly complex, the requirements for grouting materials and equipment also increase. In some karst formations with well-developed groundwater, high-velocity flowing water is often present. Under these conditions, the retention rate of conventional grout is significantly reduced, necessitating adaptive and targeted modifications to the grout by increasing adhesion viscosity and reducing setting time. However, high-viscosity grout increases pipeline resistance and exacerbates pipeline wear during pumping. Simultaneously, it increases the load on pumping equipment, raising power requirements, and prolonged high-load operation may lead to equipment failure, affecting construction progress. For fast-setting grouts, they are prone to accumulation or blockage in pipelines, resulting in uneven grouting and reduced construction quality and efficiency.

[0004] Most existing grouting materials suitable for karst water-moving strata are difficult to simultaneously meet the requirements of pumpability and erosion resistance. Preparing grout materials that meet multiple engineering performance requirements such as good pumpability, water erosion resistance, and reliable consolidation strength is a technical problem that urgently needs to be solved in the field of shield tunneling construction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-fluidity grouting material and its preparation method suitable for water-rich strata. While meeting the engineering requirements of erosion resistance and high retention rate after injection into the strata, this invention solves the problem of difficult transportation or even pipeline blockage caused by excessive viscosity of the erosion grout.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, embodiments of the present invention provide a high-fluidity grouting material suitable for water-rich strata, comprising, by weight, the following components: 16-24 parts silicate cement, 24-36 parts fly ash, 42-58 parts fine sand, 0.08-0.17 parts polyacrylamide, 0.15-0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.16-0.33 parts hydroxypropyl methylcellulose, 3.2-4.5 parts light magnesium oxide, 1-2.5 parts calcium formate, 3.2-6.8 parts calcium-based bentonite, and 90-110 parts water.

[0007] Optionally, the specific surface area of ​​the silicate cement is 450-600 m². 2 / kg.

[0008] Optionally, the specific surface area of ​​the fly ash is 250-450 m². 2 / kg, fly ash can fill the pores of slurry through the micro-aggregate effect, thereby improving the overall impermeability.

[0009] Optionally, the fine sand uses sand particles with a particle size range of 0.6-1.18 mm.

[0010] Optionally, the polyacrylamide is anionic with a molecular weight of 12 million to 18 million Da. By using polyacrylamide, the anti-segregation and uniformity of the slurry under low water-cement ratio conditions are improved.

[0011] Optionally, hydroxypropyl methylcellulose is a cold-water soluble type with a viscosity of 180,000-220,000 mPa·s. By using hydroxypropyl methylcellulose, the viscosity and anti-dispersibility of the slurry in water are improved.

[0012] Optionally, the purity of the light magnesium oxide and calcium formate is analytical grade. The use of calcium formate and light magnesium oxide can improve the early strength of the stone body and maintain volume stability during the hydration process. Calcium formate can also reduce the slurry setting time and improve the pumpability of the slurry.

[0013] Optionally, the preparation method of the viscosity-reducing polycarboxylate superplasticizer is as follows: Step 1: According to the weight parts, mix 10-14 parts of methacrylic acid and 6-10 parts of butyl methacrylate in 35-45 parts of deionized water, stir evenly, and prepare solution A; take 2-4 parts of 2-mercaptoethanol and 6-8 parts of ethylene glycol dimethacrylate, mix them in 28-32 parts of deionized water, stir evenly, and prepare solution B.

[0014] Step 2: According to the weight parts, mix 95-105 parts of methyl allyl polyoxyethylene ether and 55-65 parts of deionized water to form a mixed solution, and start heating to 60℃-70℃ while stirring. While stirring, add the prepared solution A dropwise to the mixed solution at a set first constant rate. During the dropwise addition, keep the reaction temperature at 60℃-70℃ and continue stirring.

[0015] Step 3: Dissolve 1.2-1.6 parts of potassium persulfate in 24-32 parts of deionized water. During the dissolution process, heat the water to 55-60°C and stir continuously to obtain a saturated potassium persulfate solution. Then, gradually add the saturated potassium persulfate solution dropwise to the mixed solution formed in Step 2, while continuing to stir and heat.

[0016] Step 4: Add solution B dropwise to the mixed solution formed in step 3 at the set second constant rate, continue stirring the mixed solution and keep the temperature at 60℃-70℃ until the reaction is complete.

[0017] Step 5: After the reaction is complete, the mixed solution is gradually cooled to room temperature, the pH value of the mixed solution is adjusted to neutral, and the cooled mixture is filtered to obtain the viscosity-reducing polycarboxylate superplasticizer product. Optionally, the first constant rate ensures that the dropping time of liquid A is less than 1 hour, and the second constant rate ensures that the dropping time of liquid B is less than 30 minutes.

[0018] Secondly, embodiments of the present invention provide a method for preparing a high-fluidity grouting material suitable for water-rich strata as described in the first aspect, comprising the following steps: Weigh out 75-85 parts water, 16-24 parts silicate cement, 24-36 parts fly ash, 42-58 parts fine sand, 0.15-0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.08-0.17 parts polyacrylamide, 0.16-0.33 parts hydroxypropyl methylcellulose, 1-2.5 parts calcium formate, and 3.2-4.5 parts light magnesium oxide by weight, mix thoroughly to form a flowing mortar, and then pump the flowing mortar. Weigh out 3.2-6.8 parts by weight of calcium-based bentonite and 15-25 parts by weight of water, mix thoroughly to make bentonite slurry, and then pump the bentonite slurry. Before injection into the formation, the completed bentonite slurry and flowing mortar are thoroughly mixed to form an injection slurry, which is then injected into the formation.

[0019] The beneficial effects of this invention are as follows: The grouting material and preparation method of the present invention involve pumping a flowing mortar containing a viscosity-reducing polycarboxylate superplasticizer over long distances. This significantly reduces the slurry viscosity during long-distance pumping, thereby significantly improving fluidity and pumpability, achieving high-flow pumping. Before injection into the formation, bentonite slurry and flowing mortar are mixed. Calcium-based bentonite is used to deactivate the viscosity-reducing groups, achieving high viscosity and resistance to dynamic water, or high retention under dynamic water conditions. This allows the slurry viscosity to increase and the anti-dispersion level to recover after long-distance pumping, ensuring erosion resistance and achieving high retention rate, thus balancing the requirements of pumping flow performance and erosion resistance. Detailed Implementation

[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] As described in the background section, most existing grouting materials suitable for karst strata with dynamic water flow are difficult to meet the requirements of both pumping performance and erosion resistance. In order to address the above problems, this application proposes a grouting material suitable for karst strata with dynamic water flow.

[0023] In a typical embodiment of this application, the high-fluidity grouting material suitable for water-rich strata is composed of the following components by weight: 16-24 parts silicate cement, 24-36 parts fly ash, 42-58 parts fine sand, 0.08-0.17 parts polyacrylamide, 0.15-0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.16-0.33 parts hydroxypropyl methylcellulose, 3.2-4.5 parts light magnesium oxide, 1-2.5 parts calcium formate, 3.2-6.8 parts calcium-based bentonite, and 90-110 parts water.

[0024] The silicate cement has a specific surface area of ​​450-600 m². 2 / kg, preferably 500 m 2 / kg, initial setting time is 55min.

[0025] The specific surface area of ​​the fly ash is 250-450 m². 2 / kg, preferably 350 m 2 / kg.

[0026] The fine sand uses sand particles with a particle size range of 0.6-1.18 mm, preferably 0.9 mm.

[0027] The polyacrylamide is anionic with a molecular weight of 12 million to 18 million Da, preferably 15 million Da. Hydroxypropyl methylcellulose is a cold-water soluble type with a viscosity of 180,000-220,000 MPa·s, preferably 200,000 MPa·s.

[0028] The purity grade of the light magnesium oxide and calcium formate is analytical grade.

[0029] The basic components of the grout are silicate cement, fly ash, and fine sand, providing essential performance characteristics. Fly ash fills grout pores through the micro-aggregate effect, improving overall impermeability. Polyacrylamide is used to improve the grout's anti-segregation and uniformity under low water-cement ratio conditions; hydroxypropyl methylcellulose improves the grout's viscosity and anti-dispersion properties in water; calcium formate and light magnesium oxide enhance the early strength of the aggregate and maintain volume stability during hydration. Calcium formate also reduces grout setting time and improves pumpability. A viscosity-reducing polycarboxylate superplasticizer significantly reduces grout viscosity during long-distance pumping, significantly improving fluidity and pumpability. Calcium-based bentonite is used to prepare bentonite grout, which can increase grout viscosity and restore anti-dispersion levels after long-distance pumping, and further accelerate cement hydration.

[0030] The raw materials and mass fractions of the viscosity-reducing polycarboxylate superplasticizer are as follows: 95-105 parts of methyl allyl polyoxyethylene ether, 55-65 parts of deionized water, 1.2-1.6 parts of potassium persulfate, and solutions A and B.

[0031] Solution A consists of 10-14 parts methacrylic acid, 6-8 parts butyl methacrylate, and 35-45 parts deionized water. Solution B consists of 2-mercaptoethanol, 6-8 parts ethylene glycol dimethacrylate, and 28-32 parts deionized water.

[0032] The preparation method is as follows: Step 1: According to the weight parts, mix 10-14 parts of methacrylic acid and 6-10 parts of butyl methacrylate in 35-45 parts of deionized water, stir evenly, and prepare solution A; take 2-4 parts of 2-mercaptoethanol and 6-8 parts of ethylene glycol dimethacrylate, mix them in 28-32 parts of deionized water, stir evenly, and prepare solution B.

[0033] Step 2: According to the weight parts, add 95-105 parts of methyl allyl polyoxyethylene ether and 55-65 parts of deionized water to the reactor to form a mixed solution, and start heating to 60℃-70℃. While stirring, add the prepared solution A dropwise to the mixed solution in the reactor at a set first constant rate. During the dropwise addition, maintain the reaction temperature at 60℃-70℃ and continue stirring. Control the dropwise addition time to 1 hour to ensure that the reaction proceeds uniformly.

[0034] Step 3: Dissolve 1.2-1.6 parts of potassium persulfate in 24-32 parts of deionized water. During the dissolution process, heat the water to 55-60°C and stir continuously to prepare a saturated potassium persulfate solution. Then, gradually add the saturated potassium persulfate solution dropwise to the mixed solution formed in Step 2, while continuing to stir and heat.

[0035] Step 4: Add solution B dropwise to the mixed solution formed in step 3 in the reactor at a set second constant rate. The dropwise addition time is controlled within 30 minutes. Continue stirring the mixed solution and keep the temperature at 60℃-70℃ until the reaction is complete. In this embodiment, the reaction time is 3-5 hours.

[0036] Step 5: After the reaction is complete, the mixed solution is gradually cooled to room temperature (20-30℃). An alkaline substance, such as sodium bicarbonate or sodium hydroxide, is added to adjust the pH of the mixed solution to neutral (pH 6-7). After cooling, the mixture is filtered to remove unreacted impurities to obtain the viscosity-reducing polycarboxylate superplasticizer. The first constant rate ensures that the dripping time of liquid A is less than 1 hour, and the second constant rate ensures that the dripping time of liquid B is less than 30 minutes.

[0037] Another typical embodiment of this application provides a method for preparing a high-fluidity grouting material suitable for water-rich strata, comprising the following steps: Weigh out 75-85 parts water, 16-24 parts silicate cement, 24-36 parts fly ash, 42-58 parts fine sand, 0.15-0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.08-0.17 parts polyacrylamide, 0.16-0.33 parts hydroxypropyl methylcellulose, 1-2.5 parts calcium formate, and 3.2-4.5 parts light magnesium oxide by weight, mix thoroughly to form a flowing mortar, and then pump the flowing mortar. Weigh out 3.2-6.8 parts by weight of calcium-based bentonite and 15-25 parts by weight of water, mix thoroughly to make bentonite slurry, and then pump the bentonite slurry. Before injection into the formation, the completed bentonite slurry and flowing mortar are thoroughly mixed to form an injection slurry, which is then injected into the formation.

[0038] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions of this application will be described in detail below with reference to specific embodiments and comparative examples.

[0039] Example 1 This embodiment provides a high-fluidity grouting material suitable for water-rich strata, comprising 20 parts silicate cement, 30 parts fly ash, 42 parts fine sand, 0.13 parts polyacrylamide, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.24 parts hydroxypropyl methylcellulose, 3.9 parts light magnesium oxide, 1.7 parts calcium formate, 5 parts calcium-based bentonite, and 100 parts water.

[0040] The raw materials and weight fractions of the viscosity-reducing polycarboxylate superplasticizer are as follows: 100 parts of methyl allyl polyoxyethylene ether, 60 parts of solution A, 40 parts of solution B, a saturated potassium persulfate solution containing 1.4 parts of potassium persulfate, and 60 parts of deionized water. Solution A includes 12 parts of methacrylic acid, 8 parts of butyl methacrylate, and 40 parts of deionized water. Solution B includes 3 parts of 2-mercaptoethanol, 7 parts of ethylene glycol dimethacrylate, and 30 parts of deionized water.

[0041] The preparation method of viscosity-reducing polycarboxylate superplasticizer is as follows: Step 1: Take 12 parts methacrylic acid and 8 parts butyl methacrylate, mix them in 40 parts deionized water, and stir until homogeneous to prepare solution A; take 3 parts 2-mercaptoethanol and 7 parts ethylene glycol dimethacrylate, mix them in 30 parts deionized water, and stir until homogeneous to prepare solution B. Add 100 parts methyl allyl polyoxyethylene ether and 60 parts deionized water to the reactor, and start heating to 60-70℃ while maintaining stirring.

[0042] Step 2: While heating and stirring, add the prepared solution A dropwise to the reactor at a constant rate. The dropping time should be controlled within 1 hour to ensure uniform reaction; during the dropping process, maintain the reaction temperature at 60-70℃ and continue stirring.

[0043] Step 3: After all solution A has been added, completely dissolve 1.4 parts of potassium persulfate in 28 parts of deionized water to make a saturated potassium persulfate solution. Then, gradually add the solution to the reactor while continuing to stir and heat.

[0044] Step 4: Add solution B dropwise into the reactor at a constant rate, controlling the addition time to within 30 minutes. The reaction temperature should still be maintained at 60-70°C. Continue heating and stirring the material in the reactor, maintaining the temperature at 60-70°C, for 3-5 hours until the reaction is complete.

[0045] Step 5: After the reaction is complete, stop heating and gradually cool to room temperature. Then, add a small amount of alkaline substance (such as sodium bicarbonate or sodium hydroxide) as needed to adjust the pH of the solution to neutral (pH 6-7). After cooling, filter the mixture to remove unreacted impurities, obtaining the viscosity-reducing polycarboxylate superplasticizer product.

[0046] The preparation method of the grouting material is as follows: Weigh out 80 parts water, 20 parts silicate cement, 30 parts fly ash, 42 parts fine sand, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.13 parts polyacrylamide, 0.24 parts hydroxypropyl methylcellulose, 1.7 parts calcium formate, and 3.9 parts light magnesium oxide by weight. Mix them thoroughly at the grouting mixing station in the shield tunnel section to make a flowing mortar. Then pump the flowing mortar. Weigh out 5 parts calcium-based bentonite and 20 parts water by weight, mix them thoroughly at the shield tunnel mixing station or the shield machine grouting system to make bentonite slurry, and then pump the bentonite slurry. Before injection into the stratum, the bentonite slurry and flowing mortar that have been pumped are thoroughly mixed evenly in the storage tank of the shield grouting system to form the injection slurry. Then, the injection slurry is injected into the target stratum using a plunger pump.

[0047] Example 2 This embodiment provides a high-fluidity grouting material suitable for water-rich strata, comprising 24 parts silicate cement, 36 parts fly ash, 50 parts fine sand, 0.15 parts polyacrylamide, 0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.3 parts hydroxypropyl methylcellulose, 4 parts light magnesium oxide, 2 parts calcium formate, 3.2 parts calcium-based bentonite, and 110 parts water.

[0048] The raw materials and weight fractions of the viscosity-reducing polycarboxylate superplasticizer are as follows: 95 parts methyl allyl polyoxyethylene ether, 60 parts solution A, 40 parts solution B, 1.4 parts potassium persulfate, and 60 parts deionized water. Solution A includes 10 parts methacrylic acid, 8 parts butyl methacrylate, and 40 parts deionized water. Solution B includes 3 parts 2-mercaptoethanol, 7 parts ethylene glycol dimethacrylate, and 30 parts deionized water.

[0049] The preparation method of viscosity-reducing polycarboxylate superplasticizer is as follows: Step 1: Take 10 parts methacrylic acid and 8 parts butyl methacrylate, mix them in 40 parts deionized water, and stir until homogeneous to prepare solution A; take 3 parts 2-mercaptoethanol and 7 parts ethylene glycol dimethacrylate, mix them in 30 parts deionized water, and stir until homogeneous to prepare solution B. Add 95 parts methyl allyl polyoxyethylene ether and 60 parts deionized water to the reactor, and start heating to 60-70℃ while maintaining stirring.

[0050] Step 2: While heating and stirring, add the prepared solution A dropwise to the reactor at a constant rate. The dropping time should be controlled within 1 hour to ensure uniform reaction; during the dropping process, maintain the reaction temperature at 60-70℃ and continue stirring.

[0051] Step 3: After all solution A has been added, dissolve 1.4 parts of potassium persulfate in 28 parts of deionized water to make a saturated potassium persulfate solution, and then gradually add it dropwise into the reactor while continuing to stir and heat.

[0052] Step 4: Add solution B dropwise into the reactor at a constant rate, controlling the addition time to within 30 minutes. The reaction temperature should still be maintained at 60-70°C. Continue heating and stirring the material in the reactor, maintaining the temperature at 60-70°C, for 3-5 hours until the reaction is complete.

[0053] Step 5: After the reaction is complete, stop heating and gradually cool to room temperature. Then, add a small amount of alkaline substance (such as sodium bicarbonate or sodium hydroxide) as needed to adjust the pH of the solution to neutral (pH 6-7). After cooling, filter the mixture to remove unreacted impurities, obtaining the viscosity-reducing polycarboxylate superplasticizer product.

[0054] The preparation method of the grouting material is as follows: Weigh out 85 parts water, 24 parts silicate cement, 36 parts fly ash, 50 parts fine sand, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.13 parts polyacrylamide, 0.24 parts hydroxypropyl methylcellulose, 1.7 parts calcium formate, and 3.9 parts light magnesium oxide by weight. Mix them thoroughly at the grouting mixing station in the shield tunnel section to make a flowing mortar. Then pump the flowing mortar. Weigh out 3.2 parts calcium-based bentonite and 25 parts water by weight, mix them thoroughly at the shield tunnel mixing station or the shield machine grouting system to make bentonite slurry, and then pump the bentonite slurry. Before injection into the stratum, the bentonite slurry and flowing mortar that have been pumped are thoroughly mixed evenly in the storage tank of the shield grouting system to form the injection slurry. Then, the injection slurry is injected into the target stratum using a plunger pump.

[0055] Example 3 This embodiment provides a high-fluidity grouting material suitable for water-rich strata, comprising 16 parts silicate cement, 36 parts fly ash, 58 parts fine sand, 0.17 parts polyacrylamide, 0.15 parts viscosity-reducing polycarboxylate superplasticizer, 0.33 parts hydroxypropyl methylcellulose, 4.5 parts light magnesium oxide, 2.5 parts calcium formate, 6.8 parts calcium-based bentonite, and 90 parts water.

[0056] The raw materials and weight fractions of the viscosity-reducing polycarboxylate superplasticizer are as follows: 100 parts of methyl allyl polyoxyethylene ether, 60 parts of solution A, 40 parts of solution B, a saturated potassium persulfate solution containing 1.4 parts of potassium persulfate, and 60 parts of deionized water. Solution A includes 12 parts of methacrylic acid, 8 parts of butyl methacrylate, and 40 parts of deionized water. Solution B includes 3 parts of 2-mercaptoethanol, 7 parts of ethylene glycol dimethacrylate, and 30 parts of deionized water.

[0057] The preparation method of viscosity-reducing polycarboxylate superplasticizer is as follows: Step 1: Take 12 parts methacrylic acid and 8 parts butyl methacrylate, mix them in 40 parts deionized water, and stir until homogeneous to prepare solution A; take 3 parts 2-mercaptoethanol and 7 parts ethylene glycol dimethacrylate, mix them in 30 parts deionized water, and stir until homogeneous to prepare solution B. Add 100 parts methyl allyl polyoxyethylene ether and 60 parts deionized water to the reactor, and start heating to 60-70℃ while maintaining stirring.

[0058] Step 2: While heating and stirring, add the prepared solution A dropwise to the reactor at a constant rate. The dropping time should be controlled within 1 hour to ensure uniform reaction; during the dropping process, maintain the reaction temperature at 60-70℃ and continue stirring.

[0059] Step 3: After all solution A has been added, completely dissolve 1.4 parts of potassium persulfate in 28 parts of deionized water to make a saturated potassium persulfate solution. Then, gradually add the solution to the reactor while continuing to stir and heat.

[0060] Step 4: Add solution B dropwise into the reactor at a constant rate, controlling the addition time to within 30 minutes. The reaction temperature should still be maintained at 60-70°C. Continue heating and stirring the material in the reactor, maintaining the temperature at 60-70°C, for 3-5 hours until the reaction is complete.

[0061] Step 5: After the reaction is complete, stop heating and gradually cool to room temperature. Then, add a small amount of alkaline substance (such as sodium bicarbonate or sodium hydroxide) as needed to adjust the pH of the solution to neutral (pH 6-7). After cooling, filter the mixture to remove unreacted impurities, obtaining the viscosity-reducing polycarboxylate superplasticizer product.

[0062] The preparation method of the grouting material is as follows: Weigh out 75 parts water, 16 parts silicate cement, 36 parts fly ash, 58 parts fine sand, 0.15 parts viscosity-reducing polycarboxylate superplasticizer, 0.17 parts polyacrylamide, 0.33 parts hydroxypropyl methylcellulose, 2.5 parts calcium formate, and 4.5 parts light magnesium oxide by weight. Mix them thoroughly at the grouting mixing station in the shield tunnel section to make a flowing mortar. Then pump the flowing mortar. Weigh out 6.8 parts calcium-based bentonite and 15 parts water by weight, mix them thoroughly at the shield tunnel mixing station or the shield machine grouting system to make bentonite slurry, and then pump the bentonite slurry. Before injection into the stratum, the bentonite slurry and flowing mortar that have been pumped are thoroughly mixed evenly in the storage tank of the shield grouting system to form the injection slurry. Then, the injection slurry is injected into the target stratum using a plunger pump.

[0063] Comparative Example 1 A grouting material, by mass fraction, comprises the following components: 20 parts silicate cement, 30 parts fly ash, 40 parts fine sand, 0.13 parts polyacrylamide, 0.24 parts hydroxypropyl methylcellulose, 3.9 parts light magnesium oxide, 1.7 parts calcium formate, 5 parts calcium-based bentonite, and 100 parts water.

[0064] The above-mentioned parts of silicate cement, fly ash, fine sand, polyacrylamide, hydroxypropyl methylcellulose, light magnesium oxide, calcium formate and 80 parts of water are mixed and stirred evenly to make pumping slurry; the above-mentioned parts of calcium-based bentonite are mixed and stirred evenly with 20 parts of water to make bentonite slurry.

[0065] After pumping, the pumping slurry and bentonite slurry are mixed and stirred evenly before being injected into the formation to form an injection slurry, which is then injected into the formation.

[0066] Comparative Example 2: A grouting material, by mass fraction, comprises the following components: The ingredients are: 20 parts silicate cement, 30 parts fly ash, 40 parts fine sand, 0.13 parts polyacrylamide, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.24 parts hydroxypropyl methylcellulose, 3.9 parts light magnesium oxide, 1.7 parts calcium formate, and 100 parts water. The material composition of the viscosity-reducing polycarboxylate superplasticizer is the same as in Example 1.

[0067] The above-mentioned parts of silicate cement, fly ash, fine sand, polyacrylamide, hydroxypropyl methylcellulose, light magnesium oxide, calcium formate and 80 parts of water are mixed and stirred evenly to make pumping slurry, also known as injection slurry.

[0068] Comparative Example 3: A grouting material, by mass fraction, comprises the following components: The ingredients are: 20 parts silicate cement, 30 parts fly ash, 40 parts fine sand, 0.13 parts polyacrylamide, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 3.9 parts lightweight magnesium oxide, 5 parts calcium-based bentonite, and 100 parts water. The material composition of the viscosity-reducing polycarboxylate superplasticizer is the same as in Example 1.

[0069] The above-mentioned parts of silicate cement, fly ash, fine sand, polyacrylamide, light magnesium oxide, calcium formate and 80 parts of water are mixed and stirred evenly to make pumping slurry; the above-mentioned parts of calcium-based bentonite are mixed and stirred evenly with 20 parts of water to make bentonite slurry.

[0070] After pumping, the pumping slurry and bentonite slurry are mixed and stirred evenly before being injected into the formation to form an injection slurry, which is then injected into the formation.

[0071] Comparative Example 4 A grouting material, by mass fraction, comprises the following components: The ingredients are: 20 parts silicate cement, 30 parts fly ash, 40 parts fine sand, 0.13 parts polyacrylamide, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.24 parts hydroxypropyl methylcellulose, 3.9 parts lightweight magnesium oxide, 5 parts calcium-based bentonite, and 100 parts water. The material composition of the viscosity-reducing polycarboxylate superplasticizer is the same as in Example 1.

[0072] The above-mentioned parts of silicate cement, fly ash, fine sand, polyacrylamide, hydroxypropyl methylcellulose, light magnesium oxide and 80 parts of water are mixed and stirred evenly to make pumping slurry; the above-mentioned parts of calcium-based bentonite are mixed and stirred evenly with 20 parts of water to make bentonite slurry.

[0073] After pumping, the pumping slurry and bentonite slurry are mixed and stirred evenly before being injected into the formation to form an injection slurry, which is then injected into the formation.

[0074] Comparative Example 5 A grouting material, by mass fraction, comprises the following components: The ingredients are: 20 parts silicate cement, 30 parts fly ash, 40 parts fine sand, 0.13 parts polyacrylamide, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.24 parts hydroxypropyl methylcellulose, 1.7 parts calcium formate, 5 parts calcium-based bentonite, and 100 parts water. The material composition of the viscosity-reducing polycarboxylate superplasticizer is the same as in Example 1.

[0075] The above-mentioned parts of silicate cement, fly ash, fine sand, polyacrylamide, hydroxypropyl methylcellulose, calcium formate and 80 parts of water are mixed and stirred evenly to make pumping slurry; the above-mentioned parts of calcium-based bentonite are mixed and stirred evenly with 20 parts of water to make bentonite slurry.

[0076] After pumping, the pumping slurry and bentonite slurry are mixed and stirred evenly before being injected into the formation to form an injection slurry, which is then injected into the formation.

[0077] Comparative Example 6 A grouting material, by mass fraction, comprises the following components: The ingredients are: 20 parts silicate cement, 30 parts fly ash, 40 parts fine sand, 0.23 parts viscosity-reducing polycarboxylate superplasticizer, 0.24 parts hydroxypropyl methylcellulose, 3.9 parts light magnesium oxide, 1.7 parts calcium formate, 5 parts calcium-based bentonite, and 100 parts water. The material composition of the viscosity-reducing polycarboxylate superplasticizer is the same as in Example 1.

[0078] The above-mentioned parts of silicate cement, fly ash, fine sand, hydroxypropyl methylcellulose, light magnesium oxide, calcium formate and 80 parts of water are mixed and stirred evenly to make pumping slurry; the above-mentioned parts of calcium-based bentonite are mixed and stirred evenly with 20 parts of water to make bentonite slurry.

[0079] After pumping, the pumping slurry and bentonite slurry are mixed and stirred evenly before being injected into the formation to form an injection slurry, which is then injected into the formation.

[0080] The grouting materials obtained in the examples and comparative examples were tested. Referring to GB / T 10247-2008 "Viscosity Measurement Methods" (GB / T 10247-2008), the viscosity of the grout (pumped grout and injected grout) before and after the injection of bentonite grout was measured and denoted as I and II, respectively. Referring to the "Code for Acceptance of Construction Quality of Concrete Structures" (GB / T50204-2015), the 1-day compressive strength was measured. Referring to the "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement" (GB / T 1346-2011), the initial setting time of the grout was measured, and the results are shown in the table below. The injected grouts in the above examples were allowed to flow naturally from a truncated cone to form a disc, and a covering scouring test was conducted with a water flow velocity of 0.5 m / s to determine the dynamic water retention rate. The stone formation rate of the samples cured for 28 days was determined.

[0081] Performance data of grouting materials obtained from the examples and comparative examples

[0082] Comparing Comparative Example 1 with Example 1 shows that without the addition of viscosity-reducing polycarboxylate superplasticizer, the slurry viscosity is extremely high during pumping, making it impossible to solve the problem of long-distance pumping.

[0083] Comparing Comparative Example 2 with Example 1 shows that without the addition of calcium-based bentonite, the viscosity of the slurry injected into the formation is insufficient, and the retention rate is low under dynamic water conditions.

[0084] Comparing Comparative Example 3 with Example 1 shows that without the addition of hydroxypropyl methylcellulose, the insufficient viscosity of the slurry input to the formation results in an extremely low retention rate under dynamic water conditions, and the early strength development is slightly reduced.

[0085] Comparing Comparative Example 4 with Example 1 shows that the early strength development of the material is slower when calcium formate is not added.

[0086] Comparing Comparative Example 5 with Example 1 shows that without the addition of light magnesium oxide, the early strength development of the material is slightly affected, while the stone volume is significantly affected.

[0087] Comparing Comparative Example 6 with Example 1 shows that without the addition of polyacrylamide, insufficient slurry viscosity leads to a significant reduction in retention rate under dynamic water conditions, which slightly affects the early strength development and final stone formation rate of the material.

[0088] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-fluidity grouting material suitable for water-rich strata, characterized in that, By weight, it consists of the following components: 16-24 parts silicate cement, 24-36 parts fly ash, 42-58 parts fine sand, 0.08-0.17 parts polyacrylamide, 0.15-0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.16-0.33 parts hydroxypropyl methylcellulose, 3.2-4.5 parts light magnesium oxide, 1-2.5 parts calcium formate, 3.2-6.8 parts calcium-based bentonite, and 90-110 parts water.

2. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, The specific surface area of ​​the silicate cement is 450-600 m². 2 / kg.

3. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, The specific surface area of ​​the fly ash is 250-450 m². 2 / kg.

4. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, The fine sand used has a particle size range of 0.6-1.18 mm.

5. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, The polyacrylamide is anionic with a molecular weight of 12 million to 18 million Da.

6. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, Hydroxypropyl methylcellulose is a cold-water soluble type with a viscosity of 180,000-220,000 MPa·s.

7. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, The purity grade of the light magnesium oxide and calcium formate is analytical grade.

8. The high-fluidity grouting material suitable for water-rich strata as described in claim 1, characterized in that, The preparation method of the viscosity-reducing polycarboxylate superplasticizer is as follows: Step 1: According to the weight parts, mix 10-14 parts of methacrylic acid and 6-10 parts of butyl methacrylate in 35-45 parts of deionized water, stir evenly, and prepare solution A; take 2-4 parts of 2-mercaptoethanol and 6-8 parts of ethylene glycol dimethacrylate, mix them in 28-32 parts of deionized water, stir evenly, and prepare solution B. Step 2: According to the weight parts, mix 95-105 parts of methyl allyl polyoxyethylene ether and 55-65 parts of deionized water to form a mixed solution, and start heating to 60℃-70℃ while stirring. While stirring, add the prepared solution A dropwise to the mixed solution at a set first constant rate. During the dropwise addition, keep the reaction temperature at 60℃-70℃ and continue stirring. Step 3: Dissolve 1.2-1.6 parts of potassium persulfate in 24-32 parts of deionized water. During the dissolution process, heat the water to 55-60℃ and stir constantly to prepare a saturated potassium persulfate solution. Then, a saturated potassium persulfate solution is gradually added dropwise to the mixed solution formed in step 2, while stirring and heating are continued.

9. Step 4: Add solution B dropwise to the mixed solution formed in step 3 at the set second constant rate, continue stirring the mixed solution and keep the temperature at 60℃-70℃ until the reaction is complete; Step 5: After the reaction is complete, the mixed solution is gradually cooled to room temperature, the pH value of the mixed solution is adjusted to neutral, and the cooled mixture is filtered to obtain the viscosity-reducing polycarboxylate superplasticizer product.

10. The high-fluidity grouting material suitable for water-rich strata as described in claim 8, characterized in that, The first constant rate ensures that the dripping time of liquid A is less than 1 hour, and the second constant rate ensures that the dripping time of liquid B is less than 30 minutes.

11. A method for preparing a high-fluidity grouting material suitable for water-rich strata according to any one of claims 1-9, characterized in that, Includes the following steps: Weigh out 75-85 parts water, 16-24 parts silicate cement, 24-36 parts fly ash, 42-58 parts fine sand, 0.15-0.3 parts viscosity-reducing polycarboxylate superplasticizer, 0.08-0.17 parts polyacrylamide, 0.16-0.33 parts hydroxypropyl methylcellulose, 1-2.5 parts calcium formate, and 3.2-4.5 parts light magnesium oxide by weight, mix thoroughly to form a flowing mortar, and then pump the flowing mortar. Weigh out 3.2-6.8 parts by weight of calcium-based bentonite and 15-25 parts by weight of water, mix thoroughly to make bentonite slurry, and then pump the bentonite slurry. Before injection into the formation, the completed bentonite slurry and flowing mortar are thoroughly mixed to form an injection slurry, which is then injected into the formation.

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