Shield synchronous grouting slurry suitable for water-rich stratum and preparation method thereof
Patent Information
- Application Number
- CN202611394137.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-09
- Publication Date
- 2026-10-09
AI Technical Summary
[0003]然而，在地下水位高、渗透性强的复杂地质中，传统浆液体系面临客观挑战
本发明中植酸聚多巴胺改性膨润土与铝硅酸盐改性粉体可形成协同增效作用，植酸聚多巴胺改性剂可有效改善天然膨润土分散性差、保水吸附能力弱、与胶凝组分相容性不佳的缺陷，使植酸聚多巴胺改性膨润土充分发挥保水增稠优势，提升浆液整体粘聚性能，有效抵御富水高压地层中地下水的冲刷与稀释，而铝硅酸盐改性粉体可加快浆液硬化进程，显著提升固结体早期强度。
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Figure CN122878076A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building materials technology, specifically to a grout suitable for synchronous grouting of shield tunnels in water-rich strata and its preparation method. Background Technology
[0002] In shield tunnel construction, synchronous grouting is a key process for controlling ground deformation and preventing surface subsidence. Currently, for water-rich strata, the industry mostly uses a grout system based on cement, fly ash, and bentonite, adjusting the water-to-solid ratio or adding conventional thickeners to meet basic pumping and filling requirements.
[0003] However, in complex geological conditions with high groundwater levels and high permeability, traditional grout systems face objective challenges. On the one hand, the grout is easily washed away and diluted by groundwater upon injection, leading to the loss of effective cementing components and insufficient anti-dispersion performance. On the other hand, conventional physical blending modification can only achieve simple mixing of components, resulting in a high grout bleeding rate, slow early strength development, and weak interfacial bonding between the consolidated body and the surrounding soil.
[0004] Therefore, the core problem that current technology urgently needs to solve is: how to improve the water dispersion and erosion resistance of grout in water-rich environments, while taking into account its rheological stability and early mechanical properties, so as to ensure the integrity and long-term durability of the grout consolidation body. Summary of the Invention
[0005] The purpose of this invention is to provide a grout suitable for synchronous grouting of shield tunnels in water-rich strata and its preparation method, so as to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing grout suitable for synchronous grouting in shield tunneling in water-rich strata includes the following steps: S1. Weigh out 400-500 parts of cement, 100-200 parts of fly ash, 600-800 parts of manufactured sand and 20-40 parts of phytic acid polydopamine modified bentonite by weight, and dry mix them to obtain dry mix. S2. Weigh 600-900 parts of water, add 2-6 parts of aluminosilicate modified powder, stir evenly to obtain a dispersion; S3. Add the dispersion to the dry mixture and perform wet mixing to obtain the initial slurry; S4. Let the initial grout stand and mature, and then remix it a second time to obtain a grout suitable for synchronous grouting of shield tunnels in water-rich strata.
[0007] Preferably, the preparation method of the phytic acid polydopamine modified bentonite includes the following steps: S11. Sodium-based bentonite is vacuum dried for 12-24 hours under vacuum conditions of -0.08~-0.1MPa and temperature of 70-90℃, then crushed and passed through a 200-300 mesh sieve to obtain pretreated bentonite. S12. Mix the pretreated bentonite with phytic acid polydopamine modifier evenly to obtain a bentonite mixture. S13. Add the bentonite mixture to zirconia ball milling media and dry ball mill at a speed of 800-1200 r / min for 60-120 min to obtain phytic acid polydopamine modified bentonite.
[0008] Preferably, the method for preparing the aluminosilicate modified powder includes the following steps: S21. Mix water glass solution and metakaolin dispersion, and react at 60-80℃ for 2-4 hours to obtain reaction sol; S22. The reaction sol is centrifuged and washed 2-3 times at a speed of 8000-10000 r / min, dried at a temperature of 40-60℃ for 12-24 h, and ground through a 400-600 mesh sieve to obtain aluminosilicate modified powder.
[0009] Preferably, the preparation method of the phytic acid polydopamine modifier includes the following steps: S111. Dissolve dopamine hydrochloride in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution and react for 12-24 hours at a temperature of 25-35℃ and a stirring speed of 200-400 r / min to obtain a polydopamine dispersion. S112. Add phytic acid aqueous solution dropwise to polydopamine dispersion, and add sodium hydroxide solution with a mass fraction of 4%~12% to maintain the pH value of the system at 8.0-8.5. React at a temperature of 50-70℃ for 6-12 hours to obtain a reaction mixture. S113. The reaction mixture is placed in a dialysis bag with a molecular weight cutoff of 3000-5000 Da and dialyzed for 48-72 hours. Then, it is freeze-dried at a temperature of -50~-40℃ and a vacuum degree of 10-20 Pa for 24-48 hours to obtain phytic acid polydopamine modifier.
[0010] Preferably, the cement is one or a mixture of two of PO 42.5 or PO 52.5 silicate cement; The fly ash is Grade I or Grade II fly ash; The settling and ripening time in step S4 is 15-30 minutes.
[0011] Preferably, the mass ratio of the pretreated bentonite to the phytic acid polydopamine modifier is (5-10):1; The ball-to-material ratio of the bentonite mixture to the zirconia ball milling media is (10-20):1.
[0012] Preferably, the water glass solution has a modulus of 2.2-2.5 and a mass fraction of 20-30%. The mass fraction of the metakaolin is 5-10%.
[0013] Preferably, the pH value of the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution is 8.2-8.8; The amount of dopamine hydrochloride added is 3-8% of the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution; The phytic acid aqueous solution has a mass fraction of 50%-70%; The mass ratio of the phytic acid aqueous solution to the polydopamine dispersion is (0.5-2):1.
[0014] Preferably, the dry mixing speed is 200-300 r / min and the time is 2-5 min; The wet mixing speed is 200-400 r / min, and the time is 5-8 min; The secondary mixing speed is 200-400 r / min, and the time is 3-5 min.
[0015] A grout suitable for synchronous grouting of shield tunnels in water-rich strata was prepared by the above-mentioned method.
[0016] Compared with the prior art, the beneficial effects of the present invention are: In this invention, phytic acid polydopamine modified bentonite and aluminosilicate modified powder can form a synergistic effect. The phytic acid polydopamine modifier can effectively improve the defects of natural bentonite, such as poor dispersibility, weak water retention and adsorption capacity, and poor compatibility with cementing components. This allows the phytic acid polydopamine modified bentonite to fully exert its water retention and thickening advantages, improve the overall cohesive performance of the slurry, and effectively resist the scouring and dilution of groundwater in water-rich and high-pressure formations. Meanwhile, the aluminosilicate modified powder can accelerate the hardening process of the slurry and significantly improve the early strength of the solidified body.
[0017] The two materials work together to give the grout both excellent pumpability and erosion resistance. After entering the stratum, it can quickly build up strength, taking into account both construction performance and reinforcement effect. It effectively controls stratum deformation, reduces surface settlement, and is suitable for the long-term use of shield tunneling synchronous grouting in water-rich strata. Attached Figure Description
[0018] Figure 1 This is a flow chart illustrating the preparation process of the synchronous grouting slurry for shield tunneling in water-rich strata, as described in this invention. Figure 2 This is a process flow diagram for preparing phytic acid polydopamine modified bentonite according to the present invention; Figure 3 This is a flow chart of the preparation process of the aluminosilicate modified powder of the present invention; Figure 4 This is a process flow diagram for preparing the phytic acid polydopamine modifier of the present invention; Figure 5 The image shows the physical sample of phytic acid polydopamine modified bentonite prepared in Example 3 of this invention. Figure 6 Here is a photograph of the aluminosilicate modified powder prepared in Example 3 of this invention; Figure 7 This is a physical image of the grout prepared in Example 3 of the present invention, suitable for synchronous grouting of shield tunnels in water-rich strata. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Please see Figures 1-7 The present invention provides a technical solution: I. Preparation method of auxiliary reagents 1. Preparation of Tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution For example, to prepare a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.2: accurately weigh 12.11g of tris(hydroxymethyl)aminomethane solid into a beaker, add 800g of deionized water, stir magnetically until completely dissolved, then add more deionized water until the total mass of the solution is 1000g, shake well, and you will get a tris(hydroxymethyl)aminomethane aqueous solution. Weigh 12g of concentrated hydrochloric acid, slowly add it dropwise to an appropriate amount of deionized water, add more deionized water until the total mass of the solution is 100g, shake well, and you will get a dilute hydrochloric acid solution. Immerse the pH meter probe in an aqueous solution of tris(hydroxymethyl)aminomethane and add dilute hydrochloric acid solution dropwise while stirring until the pH of the solution stabilizes at 8.2. This yields the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with the desired pH.
[0021] The preparation method for tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solutions of other pH values is the same, only the amount of dilute hydrochloric acid solution added is adjusted to achieve the target pH value.
[0022] 2. Preparation of sodium hydroxide solution For example, to prepare a 4% sodium hydroxide solution: accurately weigh 40.0g of sodium hydroxide solid into a beaker, add 960g of deionized water, and stir until homogeneous (the dissolution process is highly exothermic and requires cooling with a cold water bath). This will give you a 4% sodium hydroxide solution.
[0023] The preparation method for sodium hydroxide solutions of other mass fractions (such as 8% and 12%) is the same. The amount of material added can be adjusted according to the mass ratio of solute to solvent (for example, to prepare an 8% solution: weigh 80.0g of sodium hydroxide and add 920g of deionized water).
[0024] 3. Preparation of metakaolin dispersion Taking the preparation of a 7% metakaolin dispersion as an example: accurately weigh 70g of metakaolin powder and place it in a stirring container, add 930g of deionized water, stir evenly, and obtain a uniformly suspended metakaolin dispersion.
[0025] The preparation methods for other concentrations (5%, 10%) are the same, with the amounts of metakaolin and deionized water adjusted proportionally.
[0026] 4. Preparation of phytic acid aqueous solution For example, to prepare a 60% phytic acid aqueous solution: place 600g of phytic acid stock solution in a container, add 100g of deionized water, and stir to mix thoroughly. Other concentrations (50%, 70%) can be prepared using the same method, adjusting the amounts of stock solution and deionized water proportionally.
[0027] II. Example 1 (I) Preparation of phytic acid polydopamine modifier S111. Add 30g of dopamine hydrochloride to 1000g of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.2, and react for 12h at a temperature of 25℃ and a stirring speed of 200r / min to obtain a polydopamine dispersion.
[0028] S112. Weigh 515g of 50% phytic acid aqueous solution and slowly add it dropwise to the polydopamine dispersion. During the dropwise addition, add 4% sodium hydroxide solution dropwise simultaneously to maintain the pH of the system at 8.0. After the dropwise addition is complete, continue stirring the reaction at 50℃ for 6 hours to obtain the reaction mixture.
[0029] S113. Transfer the reaction mixture to a dialysis bag with a molecular weight cutoff of 3000 Da. Use deionized water as the dialysis medium and change the dialysis solution every 6 hours for 8 dialysis cycles. After dialysis, remove the product from the dialysis bag and place it in a freeze dryer. Freeze-dry the product for 24 hours at a temperature of -50℃ and a vacuum of 10 Pa to obtain the phytic acid polydopamine modifier. Seal and store for later use.
[0030] (II) Preparation of phytic acid-polydopamine modified bentonite S11. Place 200g of sodium-based bentonite in a vacuum drying oven and vacuum dry it for 12h under the conditions of vacuum degree of -0.08MPa and temperature of 70℃. After taking it out, crush it with an air jet mill and pass it through a 200-mesh sieve to obtain pretreated bentonite.
[0031] S12. Place 100g of pretreated bentonite and 20g of phytic acid polydopamine modifier in a three-dimensional mixer and mix evenly to obtain a bentonite mixture.
[0032] S13. Add 60g of bentonite mixture to a zirconia ball mill jar, then add 600g of zirconia ball milling media, and perform dry ball milling at 800r / min for 60min. After ball milling, sieve out the zirconia balls to obtain phytic acid polydopamine modified bentonite, and seal and store it for later use.
[0033] (III) Preparation of aluminosilicate modified powder S21. Mix 400g of water glass solution with a modulus of 2.2 and a mass fraction of 20% with 200g of metakaolin dispersion with a mass fraction of 5%, and stir continuously at 60℃ for 2 hours to obtain a reaction sol.
[0034] S22. Transfer the reaction sol to a centrifuge tube, centrifuge and wash twice at 8000 r / min, and dry at 40℃ for 12 h to obtain aluminosilicate modified powder, which is then sealed and stored for later use.
[0035] (iv) Preparation of grout suitable for synchronous grouting of shield tunnels in water-rich strata S1. Weigh 400 parts of PO 42.5 silicate cement, 100 parts of Grade II fly ash, 600 parts of manufactured sand (fineness modulus 2.3, particle size 0.15-1.18mm) and 20 parts of phytic acid polydopamine modified bentonite, put them into a twin-shaft forced mixer, and stir at 200r / min for 2min to obtain a uniform dry mix.
[0036] S2. Weigh 600 parts of deionized water and 2 parts of aluminosilicate modified powder, mix them evenly to obtain a dispersion.
[0037] S3. Slowly add the dispersion to the dry mixture obtained in step S1, and wet mix at a speed of 200 r / min for 5 min to obtain the initial slurry.
[0038] S4. Let the initial grout stand for 15 minutes to mature, and then remix it for 3 minutes at a speed of 200 r / min to obtain a grout suitable for shield tunneling in water-rich strata.
[0039] III. Example 2 (I) Preparation of phytic acid polydopamine modifier S111. Add 80g of dopamine hydrochloride to 1000g of a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.8, and react for 24h at a temperature of 35℃ and a stirring speed of 400r / min to obtain a polydopamine dispersion.
[0040] S112. Weigh 2160g of 50% phytic acid aqueous solution and slowly add it dropwise to the polydopamine dispersion. During the dropwise addition, add 12% sodium hydroxide solution dropwise simultaneously to maintain the pH of the system at 8.5. After the dropwise addition is complete, continue stirring the reaction at 70℃ for 12h to obtain the reaction mixture.
[0041] S113. Transfer the reaction mixture to a dialysis bag with a molecular weight cutoff of 5000 Da. Use deionized water as the dialysis medium and change the dialysis solution every 6 hours for 12 dialysis cycles. After dialysis, remove the product from the dialysis bag and place it in a freeze dryer. Freeze-dry the product at -40℃ and 20Pa for 48 hours to obtain the phytic acid polydopamine modifier. Seal and store for later use.
[0042] (II) Preparation of phytic acid-polydopamine modified bentonite S11. Place 400g of sodium-based bentonite in a vacuum drying oven and vacuum dry it for 24h under the conditions of -0.1MPa and 90℃. After taking it out, crush it with an air jet mill and pass it through a 300-mesh sieve to obtain pretreated bentonite.
[0043] S12. Place 200g of pretreated bentonite and 20g of phytic acid polydopamine modifier in a three-dimensional mixer and mix evenly to obtain a bentonite mixture.
[0044] S13. Add 110g of bentonite mixture to a zirconia ball mill jar, then add 2200g of zirconia ball milling media, and perform dry ball milling at 1200r / min for 120min. After ball milling, sieve out the zirconia balls to obtain phytic acid polydopamine modified bentonite, and seal and store it for later use.
[0045] (III) Preparation of aluminosilicate modified powder S21. Mix 600g of water glass solution with a modulus of 2.5 and a mass fraction of 30% with 200g of metakaolin dispersion with a mass fraction of 10%, and stir continuously at 80℃ for 4h to obtain a reaction sol.
[0046] S22. Transfer the reaction sol to a centrifuge tube, centrifuge and wash three times at 10000 r / min, and dry at 60℃ for 24 h to obtain aluminosilicate modified powder, which is then sealed and stored for later use.
[0047] (iv) Preparation of grout suitable for synchronous grouting of shield tunnels in water-rich strata S1. Weigh 500 parts of PO 42.5 silicate cement, 200 parts of Grade II fly ash, 800 parts of manufactured sand (fineness modulus 3.0, particle size 0.15-1.18mm), and 40 parts of phytic acid polydopamine modified bentonite. Put them into a twin-shaft forced mixer and stir at 300r / min for 5min to obtain a uniform dry mix.
[0048] S2. Weigh 900 parts of deionized water and add 6 parts of aluminosilicate modified powder, mix evenly to obtain a dispersion.
[0049] S3. Slowly add the dispersion obtained in step S2 to the dry mixture obtained in step S1, and wet mix at a speed of 400 r / min for 8 min to obtain the initial slurry.
[0050] S4. Let the initial grout stand for 30 minutes to mature, and then remix it for 5 minutes at a speed of 400 r / min to obtain a grout suitable for shield tunneling synchronous grouting in water-rich strata.
[0051] IV. Example 3 (I) Preparation of phytic acid polydopamine modifier S111. Add 50g of dopamine hydrochloride to 1000g of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with pH=8.2, and react for 18h at a temperature of 30℃ and a stirring speed of 300r / min to obtain a polydopamine dispersion.
[0052] S112. Weigh 1050g of 50% phytic acid aqueous solution and slowly add it dropwise to the polydopamine dispersion. During the dropwise addition, add 8% sodium hydroxide solution dropwise simultaneously to maintain the pH of the system at 8.2. After the dropwise addition is complete, continue stirring the reaction at 60℃ for 9 hours to obtain the reaction mixture.
[0053] S113. Transfer the reaction mixture to a dialysis bag with a molecular weight cutoff of 4000 Da. Use deionized water as the dialysis medium and change the dialysis solution every 6 hours for 10 dialysis cycles. After dialysis, remove the product from the dialysis bag and place it in a freeze dryer. Freeze-dry the product for 36 hours at a temperature of -45℃ and a vacuum of 15 Pa to obtain the phytic acid polydopamine modifier. Seal and store for later use.
[0054] (II) Preparation of phytic acid-polydopamine modified bentonite S11. Place 300g of sodium-based bentonite in a vacuum drying oven and vacuum dry it for 18h under the conditions of vacuum degree of -0.09MPa and temperature of 80℃. After taking it out, crush it with an air jet mill and pass it through a 250-mesh sieve to obtain pretreated bentonite.
[0055] S12. Place 150g of pretreated bentonite and 20g of phytic acid polydopamine modifier in a three-dimensional mixer and mix evenly to obtain a bentonite mixture.
[0056] S13. Add 85g of the bentonite mixture to a zirconia ball mill jar, then add 1275g of zirconia ball milling media, and perform dry ball milling at 1000 r / min for 90 min. After ball milling, sieve out the zirconia balls to obtain phytic acid polydopamine modified bentonite, seal and store for later use. For details on the appearance of the obtained phytic acid polydopamine modified bentonite, see [link to product description]. Figure 5 .
[0057] (III) Preparation of aluminosilicate modified powder S21. Mix 500g of water glass solution with a modulus of 2.2 and a mass fraction of 25% with 200g of metakaolin dispersion with a mass fraction of 7%, and stir continuously at 70℃ for 3h to obtain a reaction sol.
[0058] S22. Transfer the reactive sol to a centrifuge tube, centrifuge and wash twice at 9000 r / min, and dry at 50℃ for 18 h to obtain aluminosilicate modified powder. Store in a sealed container for later use. See attached image for the appearance of the prepared aluminosilicate modified powder. Figure 6 .
[0059] (iv) Preparation of grout suitable for synchronous grouting of shield tunnels in water-rich strata S1. Weigh 450 parts of PO 42.5 silicate cement, 150 parts of Grade II fly ash, 700 parts of manufactured sand (fineness modulus 2.6, particle size 0.15-1.18mm) and 30 parts of phytic acid polydopamine modified bentonite, put them into a twin-shaft forced mixer, and stir at 250r / min for 4min to obtain a uniform dry mix.
[0060] S2. Weigh 750 parts of deionized water and add 4 parts of aluminosilicate modified powder, mix evenly to obtain a dispersion.
[0061] S3. Slowly add the dispersion obtained in step S2 to the dry mixture obtained in step S1, and wet mix at a speed of 300 r / min for 8 min to obtain the initial slurry.
[0062] S4. Let the initially mixed grout stand for 22 minutes to mature, then remix it at 300 r / min for 4 minutes to obtain a grout suitable for synchronous grouting of shield tunnels in water-rich strata. See the attached image for details of the prepared synchronous grout for shield tunneling in water-rich strata. Figure 7 .
[0063] V. Comparative Examples Comparative Example 1 The only difference between this comparative example and Example 3 is that the phytic acid polydopamine modified bentonite is replaced with an equal amount of unmodified pretreated sodium bentonite. The other raw material types, amounts, and preparation steps are the same as in Example 3.
[0064] Comparative Example 2 The only difference between this comparative example and Example 3 is that no aluminosilicate modified powder is added; the other raw material types, amounts, and preparation steps are the same as in Example 3.
[0065] Comparative Example 3 The difference between this comparative example and Example 3 is that: an equal amount of pretreated sodium-based bentonite is used instead of phytic acid polydopamine modified bentonite, and the use of aluminosilicate modified powder is cancelled. The other raw material types, amounts and preparation steps are the same as in Example 3.
[0066] VI. Performance Testing Methods The following performance tests were conducted on the grouts suitable for synchronous grouting of shield tunnels in water-rich strata prepared in Examples 1-3 and Comparative Examples 1-3: (1) Initial fluidity: Tested according to GB / T 2419-2005 "Method for Determination of Flowability of Cement Mortar" to reflect the pumping fluidity of the slurry.
[0067] (2) Bleeding rate: Tested in accordance with GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", reflecting the rheological stability and water retention and anti-segregation ability of the slurry.
[0068] (3) Compressive strength: Standard test blocks were made in accordance with GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The compressive strength at 3d and 28d was tested under standard curing conditions to reflect the early and late mechanical properties of the grout.
[0069] (4) Underwater molding strength retention rate (water dispersibility): The mixed slurry was directly injected into an underwater environment with a water depth of 50cm to form test blocks. After curing for 28 days, the underwater compressive strength was tested; at the same time, standard molded test blocks were made in the air and tested for 28-day compressive strength. The ratio of the two (underwater molding strength / standard molding strength × 100%) was calculated. The higher the value, the stronger the slurry's resistance to water dispersibility and erosion in a water-rich environment.
[0070] VII. Performance Test Results The performance test results of the synchronous grouting slurries for shield tunneling in water-rich strata prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1: Table 1: Performance Test Results As shown in Table 1, the performance of Examples 1-3, which simultaneously added phytic acid polydopamine modified bentonite and aluminosilicate modified powder, was superior to that of Comparative Examples 1-3, which used only a single component or no modified component. The combination of the two modified materials can achieve synergistic performance improvement.
[0071] The comparison shows that when phytic acid-polydopamine modified bentonite was missing (Comparative Example 1), the slurry bleeding rate increased to 6.8% and the underwater molding strength retention rate decreased to 58.4%, indicating that the modified bentonite can reduce slurry bleeding and improve the slurry's ability to resist groundwater scouring and dilution. When aluminosilicate modified powder was missing (Comparative Example 2), the slurry's 3-day compressive strength decreased to 1.5 MPa and its 28-day compressive strength decreased to 8.2 MPa, indicating that aluminosilicate modified powder can accelerate the slurry hardening speed and improve the strength of the solidified body. When neither of the two modified materials was added (Comparative Example 3), the slurry bleeding rate increased to 8.5%, the underwater molding strength retention rate was only 45.2%, and the 3-day and 28-day compressive strengths decreased significantly, proving that the combination of the two types of materials can simultaneously improve the slurry's water retention, scouring resistance, and hardening strength.
[0072] In summary, the grout provided by this invention for simultaneous shield tunneling in water-rich strata, through the synergistic effect of phytic acid-modified polydopamine bentonite and aluminosilicate-modified powder, not only endows the grout with suitable pumpability and extremely low bleeding rate, ensuring rheological stability during construction, but more importantly, it significantly improves the grout's resistance to water dispersion and erosion in water-rich environments, and can rapidly establish early strength, ensuring the long-term mechanical properties and durability of the consolidated body. This grout is suitable for the stringent working conditions of simultaneous shield tunneling in water-rich strata, effectively controlling stratum deformation and reducing surface settlement, and has extremely high engineering application value and promising prospects for promotion.
[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing grout suitable for synchronous grouting of shield tunnels in water-rich strata, characterized in that, Includes the following steps: S1. Weigh out 400-500 parts of cement, 100-200 parts of fly ash, 600-800 parts of manufactured sand and 20-40 parts of phytic acid polydopamine modified bentonite by weight, and dry mix them to obtain dry mix. S2. Weigh 600-900 parts of water, add 2-6 parts of aluminosilicate modified powder, stir evenly to obtain a dispersion; S3. Add the dispersion to the dry mixture and perform wet mixing to obtain the initial slurry; S4. Let the initial grout stand and mature, and then remix it a second time to obtain a grout suitable for synchronous grouting of shield tunnels in water-rich strata.
2. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 1, characterized in that, The preparation method of the phytic acid polydopamine modified bentonite includes the following steps: S11. Sodium-based bentonite is vacuum dried for 12-24 hours under vacuum conditions of -0.08~-0.1MPa and temperature of 70-90℃, then crushed and passed through a 200-300 mesh sieve to obtain pretreated bentonite. S12. Mix the pretreated bentonite with phytic acid polydopamine modifier evenly to obtain a bentonite mixture. S13. Add the bentonite mixture to zirconia ball milling media and dry ball mill at a speed of 800-1200 r / min for 60-120 min to obtain phytic acid polydopamine modified bentonite.
3. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 1, characterized in that, The preparation method of the aluminosilicate modified powder includes the following steps: S21. Mix water glass solution and metakaolin dispersion, and react at 60-80℃ for 2-4 hours to obtain reaction sol; S22. The reaction sol is centrifuged and washed 2-3 times at a speed of 8000-10000 r / min, dried at a temperature of 40-60℃ for 12-24 h, and ground through a 400-600 mesh sieve to obtain aluminosilicate modified powder.
4. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 2, characterized in that, The preparation method of the phytic acid polydopamine modifier includes the following steps: S111. Dissolve dopamine hydrochloride in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution and react for 12-24 hours at a temperature of 25-35℃ and a stirring speed of 200-400 r / min to obtain a polydopamine dispersion. S112. Add phytic acid aqueous solution dropwise to polydopamine dispersion, and add sodium hydroxide solution with a mass fraction of 4%~12% to maintain the pH value of the system at 8.0-8.
5. React at a temperature of 50-70℃ for 6-12 hours to obtain a reaction mixture. S113. The reaction mixture is placed in a dialysis bag with a molecular weight cutoff of 3000-5000 Da and dialyzed for 48-72 hours. Then, it is freeze-dried at a temperature of -50~-40℃ and a vacuum degree of 10-20 Pa for 24-48 hours to obtain phytic acid polydopamine modifier.
5. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 1, characterized in that, The cement is one or a mixture of two of PO 42.5 or PO 52.5 silicate cement; The fly ash is Grade I or Grade II fly ash; The settling and ripening time in step S4 is 15-30 minutes.
6. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 2, characterized in that, The mass ratio of the pretreated bentonite to the phytic acid polydopamine modifier is (5-10):1; The ball-to-material ratio of the bentonite mixture to the zirconia ball milling media is (10-20):
1.
7. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 3, characterized in that, The water glass solution has a modulus of 2.2-2.5 and a mass fraction of 20-30%. The mass fraction of the metakaolin is 5-10%.
8. The method for preparing a synchronous grouting slurry for shield tunneling in water-rich strata according to claim 4, characterized in that, The pH value of the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution is 8.2-8.8; The amount of dopamine hydrochloride added is 3-8% of the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution; The phytic acid aqueous solution has a mass fraction of 50%-70%; The mass ratio of the phytic acid aqueous solution to the polydopamine dispersion is (0.5-2):
1.
9. The method for preparing a synchronous grouting fluid for shield tunneling in water-rich strata according to claim 1, characterized in that, The dry mixing speed is 200-300 r / min, and the time is 2-5 min; The wet mixing speed is 200-400 r / min, and the time is 5-8 min; The secondary mixing speed is 200-400 r / min, and the time is 3-5 min.
10. A grout suitable for synchronous grouting of shield tunnels in water-rich strata, characterized in that, The grout suitable for synchronous grouting of shield tunnels in water-rich strata is prepared by the preparation method described in any one of claims 1-9.