Preparation method of a magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels

Abstract

The present invention relates to the technical field of the preparation of cement-based materials, and specifically discloses a preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel: (1) Mix metakaolin with a solution containing Mg<supgt;2+< / supgt;, add an alkali solution, then calcine, and grind the calcined product to obtain activated metakaolin. (2) Mix municipal solid waste incineration fly ash with phosphoric acid, dry, then mix with an alkali solution and dry again to obtain activated fly ash. (3) Mix the activated metakaolin with dead-burned magnesia powder and fly ash to form an alkaline component. Mix phosphate, retarder and activated fly ash to form an acidic component. (4) Mix the magnesium phosphate cement-based material containing the alkaline component and the acidic component with mixing water, etc., to obtain the grouting material. The grouting material prepared by the present invention has the technical advantages of rapid hardening and early strength, excellent impermeability performance, good slurry stability, strong toughness, being beneficial to avoiding the floating of segments, improving the structural performance of the filling layer, and ensuring the service safety of the subsea tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of cement-based materials, and particularly to a preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel. Background Art

[0002] The shield method has been gradually widely used in the construction of subsea tunnels. During the construction process, in order to effectively control the formation and maintain the stable segment structure, the means of synchronous grouting is usually adopted. Synchronous grouting is a construction method in which a slurry is injected into the shield tail gap through the grouting holes reserved at the shield tail, which can timely fill the annular gap between the segment and the formation. The filling layer formed after the slurry solidifies and hardens together with the surrounding rock and the segment maintains the stability of the subsea tunnel and ensures the service safety of the subsea tunnel.

[0003] Traditional synchronous grouting materials are usually inert slurries. Such grouting materials have problems such as a long setting time, low early strength of the formed filling layer, and the floating of segments due to the segregation phenomenon of solid components in the slurry, resulting in a reduction in the overall structural strength of the tunnel. In addition, a long setting time will also bring serious segregation problems, resulting in poor slurry stability. Moreover, in the face of the complex service environment of subsea tunnels, the filling layer formed by traditional synchronous grouting materials is easily eroded by seawater, resulting in strength loss, which has an adverse impact on the service safety of subsea tunnels. Summary of the Invention

[0004] In view of the above problems, the present invention provides a preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel. The grouting material obtained by this method has technical advantages such as rapid hardening and early strength, excellent impermeability performance, and good slurry stability. Specifically, the technical solution of the present invention is as follows.

[0005] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel includes the following steps:

[0006] (1) Mix metakaolin uniformly with a solution containing Mg 2+ and then add an alkali solution and mix uniformly. Calcine the obtained metakaolin, and then grind the calcined product to obtain activated metakaolin.

[0007] (2) Mix municipal solid waste incineration fly ash uniformly with phosphoric acid and then perform a drying treatment. Then mix the obtained pretreated fly ash uniformly with an alkali solution and perform a drying treatment again to obtain activated fly ash.

[0008] (3) Mix the activated metakaolin, dead-burned magnesia powder, and fly ash uniformly to form an alkaline component for standby. Mix phosphates, a retarder, and the activated fly ash uniformly to form an acidic component for standby.

[0009] (4) Take the following raw materials: magnesium phosphate cement-based material, fine aggregate, fiber, toughening agent, stabilizer, defoaming agent, water reducing agent, and mixing water. The magnesium phosphate cement-based material is formed by the alkaline component and the acidic component. Mix the above raw materials evenly to obtain the magnesium phosphate cement-based synchronous grouting material.

[0010] Further, in step (1), the solid-liquid ratio of the metakaolin to the Mg 2+ solution is 1 g: 2 - 3.5 ml. The mass fraction of the Mg 2+ solution is 10 - 20%. Optionally, the Mg 2+ solution includes at least one of magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium bicarbonate solution, etc.

[0011] Further, in step (1), the molar ratio of OH - provided by the alkali solution to Mg 2+ is 2.2 - 2.5:1. Optionally, the alkali solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, etc.

[0012] Further, in step (1), the calcination temperature is 550 - 700 °C, and the time is 60 - 70 min.

[0013] Further, in step (1), the fineness of the activated metakaolin is 200 - 300 mesh.

[0014] Further, in step (2), the solid-liquid ratio of the waste incineration fly ash to phosphoric acid is 1 g: 1 - 1.5 ml. Optionally, the mass fraction of the phosphoric acid is 5 - 15%.

[0015] Further, in step (2), the temperature of the drying treatment is 70 - 90 °C, and the time is 40 - 50 min to reduce the moisture in the waste incineration fly ash.

[0016] Further, in step (2), the solid-liquid ratio of the pretreated fly ash to the alkali solution is 1 g: 1 - 2 ml, and the mass fraction of the alkali solution is 10 - 18%. Optionally, the alkali solution includes at least one of potassium hydroxide, potassium bicarbonate, ammonium bicarbonate solution, etc.

[0017] Further, in step (2), the temperature of the re-drying treatment is 40 - 60 °C, and the time is 80 - 110 min.

[0018] Further, in step (3), the weight ratio of the activated metakaolin, dead-burned magnesia powder, and fly ash is 25 - 40 parts: 60 - 90 parts: 30 - 50 parts.

[0019] Further, in step (3), the weight ratio of the phosphate, retarder, and activated fly ash is 20-45 parts: 4.5-12 parts: 5-15 parts. Optionally, the phosphate includes at least one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, etc. The retarder includes at least one of boric acid, borax, zinc sulfate, etc.

[0020] Further, in step (4), the mass ratio of the basic component to the acidic component is 3-5:1.

[0021] Further, in step (4), the stabilizer is formed by cellulose, nano-SiO2, triethanolamine, and sodium silicate in a mass ratio of 0.1-0.5:1-5:0.1-0.5:0.05-0.5. Optionally, the cellulose includes at least one of hydroxypropyl methylcellulose, hydroxymethylcellulose, hydroxypropyl cellulose, etc. This stabilizer can effectively improve the stability of the grouting material of the present invention and alleviate the above-mentioned problem of segment floating.

[0022] Further, in step (4), the proportions of the components in the raw materials are as follows: 150-200 parts by weight of magnesium phosphate cement-based material, 50-80 parts by weight of fine aggregate, 1-5 parts by weight of fiber, 1-3 parts by weight of toughening agent, 1-10 parts by weight of stabilizer, 0.2-1 part by weight of defoaming agent, 3-10 parts by weight of water reducing agent, and 40-60 parts by weight of mixing water.

[0023] Further, in step (4), the toughening agent includes at least one of ethylene / vinyl acetate copolymer powder (EVA) powder, styrene-butadiene rubber powder, etc.

[0024] Further, in step (4), the fiber includes at least one of carbon fiber, polyvinyl alcohol fiber, polyethylene fiber, polypropylene fiber, etc. Optionally, the length of the fiber is 2-4 mm and the diameter is 5-10 μm.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] The synchronous grouting material for reinforcing subsea shield tunnels in the present invention uses a magnesium phosphate cement-based material as the main cementitious component, which features a fast setting rate and high early strength of the filling material formed after hardening. Meanwhile, the organic film formed by the toughening agent not only increases the toughness of the filling material, improves the anti-deformation ability of the material, but also enhances the water resistance and impermeability of the material, thus better ensuring the service safety of the subsea tunnel. Additionally, the magnesium phosphate cement-based synchronous grouting material of the present invention also adds a stabilizer formed by the cellulose, nano-SiO2, triethanolamine, and water glass, enabling the grouting material prepared in the present invention to have high stability, avoiding the segregation phenomenon of the material caused by the floating of solid raw materials such as dead-burned magnesia due to their own gravity, thereby preventing the segment from floating and enhancing the structural performance of the filling material. This is because the cellulose and nano-SiO2 in the stabilizer can adhere to the surface of larger particles to play a role in dispersion, lifting and suspension, improving the stability of the grouting material and preventing the aggregation and sedimentation of particles. The triethanolamine not only promotes the hydration reaction of the cement material as a catalyst but also helps to improve the material uniformity, ensuring the full hydration of the cement material. The water glass can increase the viscosity of the material, further preventing the solid-liquid stratification phenomenon.

[0027] In addition, the present invention uses a magnesium phosphate cement-based material prepared by combining the alkaline component formed by the reactive metakaolin, dead-burned magnesia powder, and fly ash with the acidic component formed by phosphate, retarder, and activated fly ash. The addition of the modified metakaolin and activated fly ash can make the structure of the filling material formed after the hardening of the magnesium phosphate cement-based material more dense, improve the impermeability while enhancing the mechanical properties, and at the same time realize the resource utilization of waste incineration fly ash. This is because: First, the present invention uses a solution containing Mg 2+ and an alkali solution to treat the metakaolin, thereby forming magnesium hydroxide on the metakaolin particles, which is converted into magnesia after calcination treatment, so that magnesia is loaded on the metakaolin particles to form reactive metakaolin. Meanwhile, under the action of the alkaline component provided by the alkali solution and high-temperature calcination, the inert mineral phase of the metakaolin depolymerizes to form an active structure [AlO4] 5-etc., which can react with the sodium silicate in the stabilizer to form calcium aluminosilicate hydrate (C-A-S-H) gel components, helping to better combine metakaolin particles with other materials and improve the strength of the filling material. In addition, in the present invention, the municipal solid waste incineration fly ash is pretreated with phosphoric acid first, so as to convert the heavy metal elements in the fly ash into phosphates for solidification and prevent them from being secondarily dissolved and polluting the marine environment after entering the filling material. Further, the present invention uses an alkali solution to treat the above fly ash, so as to form phosphates by reacting the residual phosphoric acid in the fly ash with the alkali solution and load them on the fly ash to form activated fly ash. After using it as a raw material of the magnesium phosphate cement-based material, it can carry out a hydration reaction with the dead-burned magnesia in the alkaline component and the magnesia on the metakaolin. At the same time, the metakaolin can also carry out a hydration reaction with the phosphate in the acidic component by using its magnesia, so that the metakaolin and fly ash have the same type of reaction activity as the hydration reaction of the magnesium phosphate cement, enabling the metakaolin and fly ash to not only play a role in densifying the hydration products of the magnesium phosphate cement, but also be cemented together with the hydration products of the magnesium phosphate cement through the gel hydration products formed by their hydration reactions, improving the strength of the formed filling material. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0029] Figure 1 It is a sample diagram of the magnesium phosphate cement-based synchronous grouting material prepared for the following Example 1.

[0030] Figure 2 It is a compressive strength test diagram for the following Example 1.

[0031] Figure 3 It is an impermeability and erosion resistance test diagram for the following Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer.

[0033] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to persons skilled in the art. The reagents or raw materials used in the present invention can be obtained by conventional means. Unless otherwise specified, the reagents or raw materials used in the present invention are used in accordance with the conventional methods in the art or in accordance with the product instructions. In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the present invention. The technical solution of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0034] Example 1

[0035] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel includes the following steps:

[0036] (1) Mix metakaolin with a magnesium sulfate solution with a mass fraction of 15% at a solid-liquid ratio of 1 g: 3 ml and stir evenly. Then add sodium hydroxide solution and stir evenly according to the molar ratio of OH - to Mg 2+ of 2.3: 1 to obtain pretreated metakaolin. Heat the pretreated metakaolin to 650 °C and keep it warm for 60 min. Cool the obtained calcined product to room temperature and then grind it, and then pass through a 300-mesh sieve to obtain activated metakaolin for standby.

[0037] (2) Mix municipal solid waste incineration fly ash with phosphoric acid with a mass fraction of 10% at a solid-liquid ratio of 1 g: 1.5 ml, let it stand for 20 min, and then dry it at 80 °C for 45 min to obtain pretreated fly ash. Mix the pretreated fly ash with a potassium hydroxide solution with a mass fraction of 15% at a ratio of 1 g: 2 ml and stir evenly, and then dry it at 50 °C for 90 min to obtain activated fly ash for standby.

[0038] (3) Mix the activated metakaolin prepared in this example, dead-burned magnesia powder, and fly ash evenly at a ratio of 30 parts by weight: 80 parts by weight: 40 parts by weight to form an alkaline component for standby.

[0039] (4) Mix potassium dihydrogen phosphate, borax, and the activated fly ash prepared in this example evenly at a ratio of 40 parts by weight: 10 parts by weight: 10 parts by weight to form an acidic component. Mix the alkaline component and the acidic component at a mass ratio of 4: 1 and stir evenly to obtain a magnesium phosphate cement-based material for standby.

[0040] (5) Mix hydroxypropyl methylcellulose, nano-SiO2, triethanolamine, and water glass evenly at a mass ratio of 0.2: 3: 0.35: 0.25 to form a stabilizer for standby.

[0041] (6) Take the following raw materials in parts by weight: 180 parts of the magnesium phosphate cement-based material prepared in this example, 70 parts of 50-mesh machine-made sand fine aggregate, 3 parts of carbon fiber (length 3 mm, diameter 10 μm), 2 parts of toughening agent (ethylene / vinyl acetate copolymer rubber powder (EVA), model 5010N, purchased from Wacker Chemical (China) Co., Ltd.), 6 parts of stabilizer, 0.8 parts of defoaming agent (tributyl phosphate, purchased from Chengdu Clone Chemical Reagent Factory), 7 parts of polycarboxylic acid water reducer, and 50 parts of mixing water.

[0042] (7) First, stir the magnesium phosphate cement-based material, machine-made sand fine aggregate, fiber, and toughening agent for 3 minutes, then add the stabilizer and stir for 2 minutes. After completion, add the defoamer, water reducer, and mixing water and stir for 2 minutes to obtain the magnesium phosphate cement-based synchronous grouting material.

[0043] Performance Test:

[0044] 1. The stability of the magnesium phosphate cement-based synchronous grouting material prepared in this embodiment is tested. The specific method is as follows: if there is no water precipitation before the grouting material hardens, and the color of the side of the test piece is uniform, it is defined as "good stability". If there is no water precipitation before the grouting material hardens, and the bottom and top of the test piece are uneven in color, it is defined as "good stability". If there is water precipitation before the grouting material hardens, it is defined as "poor stability".

[0045] 2. The magnesium phosphate cement-based synchronous grouting material prepared in this embodiment is poured into a mold to form a mold, and then the molded specimen is demoulded and naturally cured for 1 day. Then, according to the "Test Method for Cement Mortar Strength (ISO Method)" (GB / T17671-2021), a universal press is used to test the 1d compressive strength of the obtained specimen (such as Figure 2 as shown).

[0046] 3. The anti-seepage and anti-corrosion properties of the test pieces prepared by the magnesium phosphate cement-based synchronous grouting material prepared in this embodiment are tested. The specific method is: the test pieces of the same batch prepared by the above method are placed in artificially prepared simulated seawater (the configuration of the simulated seawater refers to Alexander.A, that is, each 1L of water contains 24.53g of NaCl, 5.20g of MgCl2, 4.09g of Na2SO4, and 1.16g of CaCl2) and immersed (as shown in FIG. Figure 3 As shown), the compressive strength was tested after 3 days. The strength retention rate is the ratio of the compressive strength of the specimen after seawater immersion to the 1d compressive strength. The higher the compressive strength and strength retention rate after seawater immersion, the stronger the anti-seepage and erosion resistance of the magnesium phosphate cement-based synchronous grouting material. The test results of the above performance indicators are shown in the following table.

[0047]

[0048] Example 2

[0049] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel, comprising the following steps:

[0050] (1) Mix metakaolin with a 20% by mass magnesium nitrate solution at a solid-liquid ratio of 1 g: 2 ml and stir evenly. Then add potassium hydroxide solution according to the molar ratio of OH - to Mg 2+ of 2.5:1 and stir evenly to obtain pretreated metakaolin. Heat the pretreated metakaolin to 550 °C and keep it warm for 70 min. After cooling the obtained calcined product to room temperature, grind it and then pass through a 200-mesh sieve to obtain activated metakaolin for standby.

[0051] (2) Mix municipal solid waste incineration fly ash with 15% by mass phosphoric acid at a solid-liquid ratio of 1 g: 1.0 ml, let it stand for 20 min, and then dry it at 70 °C for 50 min to obtain pretreated fly ash. Mix the pretreated fly ash with 18% by mass ammonium bicarbonate solution at a ratio of 1 g: 1.0 ml, stir evenly, and then dry it at 40 °C for 110 min to obtain activated fly ash for standby.

[0052] (3) Mix the activated metakaolin prepared in this example, dead-burned magnesia powder, and fly ash evenly according to the ratio of 25 parts by weight: 60 parts by weight: 30 parts by weight to form an alkaline component for standby.

[0053] (4) Mix ammonium dihydrogen phosphate, boric acid, and the activated fly ash prepared in this example evenly according to the ratio of 20 parts by weight: 4.5 parts by weight: 5 parts by weight to form an acidic component. Mix the alkaline component and the acidic component according to a mass ratio of 3:1 and stir evenly to obtain a magnesium phosphate cement-based material for standby.

[0054] (5) Mix carboxymethyl cellulose, nano-SiO2, triethanolamine, and water glass evenly according to a mass ratio of 0.1: 1: 0.1: 0.05 to form a stabilizer for standby.

[0055] (6) By weight, take the following raw materials: 150 parts of the magnesium phosphate cement-based material prepared in this example, 50 parts of 80-mesh machine-made sand fine aggregate, 1 part of polyvinyl alcohol fiber (length 4 mm, diameter 10 μm), 1 part of toughening agent (styrene-butadiene rubber powder, purchased from Wacker Chemical (China) Co., Ltd.), 1 part of stabilizer, 0.2 part of defoaming agent (tributyl phosphate, purchased from Chengdu Kelong Chemical Reagent Factory), 3 parts of polycarboxylate water reducer, and 40 parts of mixing water.

[0056] (7) First, stir the magnesium phosphate cement-based material, manufactured sand fine aggregate, fiber, and toughening agent for 2 minutes, and then add the stabilizer and stir for 1 minute. After completion, add the defoaming agent, water reducing agent, and mixing water and stir for 2 minutes to obtain the magnesium phosphate cement-based synchronous grouting material.

[0057] Using the same method as in Example 1 above, test the performance indicators of the magnesium phosphate cement-based synchronous grouting material prepared in this example. The results are shown in the following table.

[0058]

[0059] Example 3

[0060] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel includes the following steps:

[0061] (1) Mix metakaolin and a 10% mass fraction magnesium acetate solution according to a solid-liquid ratio of 1 g: 3.5 ml and stir evenly. Then, add ammonia water according to a molar ratio of OH - to Mg 2+ of 2.2: 1 and stir evenly to obtain pretreated metakaolin. Heat the pretreated metakaolin to 700 °C and keep it warm for 60 minutes. After cooling the obtained calcined product to room temperature, grind it and then pass it through a 250-mesh sieve to obtain activated metakaolin for standby.

[0062] (2) Mix municipal solid waste incineration fly ash and 5% mass fraction phosphoric acid according to a solid-liquid ratio of 1 g: 1.5 ml, let it stand for 20 minutes, and then dry it at 90 °C for 40 minutes to obtain pretreated fly ash. Mix the pretreated fly ash and a 10% mass fraction potassium bicarbonate solution according to a ratio of 1 g: 2.0 ml, stir evenly, and then dry it at 60 °C for 80 minutes to obtain activated fly ash for standby.

[0063] (3) Mix the activated metakaolin prepared in this example, dead-burned magnesia powder, and fly ash according to a ratio of 45 parts by weight: 90 parts by weight: 50 parts by weight to form an alkaline component for standby.

[0064] (4) Mix ammonium dihydrogen phosphate, zinc sulfate, and the activated fly ash prepared in this example according to a ratio of 45 parts by weight: 12 parts by weight: 15 parts by weight to form an acidic component. Mix the alkaline component and the acidic component according to a mass ratio of 5: 1 and stir evenly to obtain the magnesium phosphate cement-based material for standby.

[0065] (5) Mix hydroxypropyl cellulose, nano-SiO2, triethanolamine, and water glass according to a mass ratio of 0.5: 5: 0.5: 0.5 and stir evenly to form a stabilizer for standby.

[0066] (6) Take the following raw materials by weight: 200 parts of the magnesium phosphate cement-based material prepared in this example, 80 parts of 40-mesh machine-made sand fine aggregate, 5 parts of polyethylene fiber (length 2 mm, diameter 5 μm), 3 parts of toughening agent (composed of EVA rubber powder and styrene-butadiene rubber powder in a mass ratio of 1:3, and the rubber powder is purchased from Wacker Chemical (China) Co., Ltd.), 10 parts of stabilizer, 1 part of defoaming agent (tributyl phosphate, purchased from Chengdu Kelong Chemical Reagent Factory), 10 parts of polycarboxylate water reducer, and 60 parts of mixing water.

[0067] (7) First, stir the magnesium phosphate cement-based material, machine-made sand fine aggregate, fiber, and toughening agent for 3 min, and then add the stabilizer and stir for 2 min. After completion, add the defoaming agent, water reducer, and mixing water and stir for 2 min to obtain the magnesium phosphate cement-based synchronous grouting material.

[0068] Use the same method as in Example 1 above to test the performance indicators of the magnesium phosphate cement-based synchronous grouting material prepared in this example, and the results are shown in the following table.

[0069]

[0070] Example 4

[0071] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel is the same as that in Example 1 above, except that the magnesium phosphate cement-based material in this example is prepared by the following method:

[0072] (1) Mix metakaolin with a 15% mass fraction of magnesium sulfate solution at a solid-liquid ratio of 1 g:3 ml and stir evenly to obtain pretreated metakaolin. Heat the pretreated metakaolin to 650 °C and keep it warm for 60 min. After cooling the obtained calcined product to room temperature, grind it and then pass through a 300-mesh sieve to obtain activated metakaolin for standby.

[0073] (2) Mix the activated metakaolin prepared in this example, dead-burned magnesia powder, and fly ash evenly in a ratio of 30 parts by weight: 80 parts by weight: 40 parts by weight to form an alkaline component for standby.

[0074] (3) Mix the alkaline component prepared in this example and the acidic component prepared in Example 1 above at a mass ratio of 4:1 and stir evenly to obtain the magnesium phosphate cement-based material.

[0075] Use the same method as in Example 1 above to test the performance indicators of the magnesium phosphate cement-based synchronous grouting material prepared in this example, and the results are shown in the following table.

[0076]

[0077] Example 5

[0078] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel, comprising the following steps:

[0079] (1) By weight, take the following raw materials: 180 parts of the magnesium phosphate cement-based material prepared in Example 1 above, 70 parts of 50-mesh machine-made sand fine aggregate, 3 parts of carbon fiber (length 3 mm, diameter 10 μm), 2 parts of toughening agent (ethylene / vinyl acetate copolymer powder (EVA), model 5010N, purchased from Wacker Chemical (China) Co., Ltd.), 0.8 part of defoaming agent (tributyl phosphate, purchased from Chengdu Kelong Chemical Reagent Factory), 7 parts of polycarboxylate water reducer, and 50 parts of mixing water.

[0080] (2) First, stir the magnesium phosphate cement-based material, the machine-made sand fine aggregate, the fiber, and the toughening agent for 3 min, and then add the defoaming agent, the water reducer, and the mixing water and stir for 2 min to obtain the magnesium phosphate cement-based synchronous grouting material.

[0081] The same method as in Example 1 above was used to test the performance indexes of the magnesium phosphate cement-based synchronous grouting material prepared in this example, and the results are shown in the following table.

[0082]

[0083] Example 6

[0084] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel is the same as that in Example 3 above, except that the magnesium phosphate cement-based material in this example is prepared by the following method:

[0085] (1) Mix metakaolin with a 10% mass fraction of magnesium acetate solution according to a solid-liquid ratio of 1 g: 3.5 ml and stir evenly. Then add ammonia water according to a molar ratio of OH - to Mg 2+ of 2.2:1 and stir evenly to obtain pretreated metakaolin. Heat the pretreated metakaolin to 70 °C and keep it warm for 60 min, grind the obtained product and pass it through a 250-mesh sieve to obtain activated metakaolin for standby.

[0086] (2) Mix the activated metakaolin prepared in this example, the dead-burned magnesia powder, and the fly ash evenly according to a ratio of 45 parts by weight: 90 parts by weight: 50 parts by weight to form an alkaline component for standby.

[0087] (3) Mix the alkaline component prepared in this example and the acidic component prepared in Example 3 above according to a mass ratio of 5:1 and stir evenly to obtain the magnesium phosphate cement-based material.

[0088] The same method as in the above-mentioned Example 1 was used to test the performance indexes of the magnesium phosphate cement-based synchronous grouting material prepared in this example, and the results are shown in the following table.

[0089]

[0090] Example 7

[0091] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel is the same as that in the above-mentioned Example 2, except that the magnesium phosphate cement-based material in this example is prepared by the following method:

[0092] (1) The waste incineration fly ash and phosphoric acid with a mass fraction of 15% were mixed at a solid-liquid ratio of 1 g: 1.0 ml, and then left standing for 20 min, and then dried at 70 °C for 50 min to obtain pretreated fly ash, which was reserved for use.

[0093] (2) Ammonium dihydrogen phosphate, boric acid and the pretreated fly ash prepared in this example were mixed evenly at a ratio of 20 parts by weight: 4.5 parts by weight: 5 parts by weight to form an acidic component, which was reserved for use.

[0094] (3) The alkaline component prepared in the above-mentioned Example 2 and the acidic component prepared in this example were mixed at a mass ratio of 3:1 and stirred evenly to obtain the magnesium phosphate cement-based material.

[0095] The same method as in the above-mentioned Example 1 was used to test the performance indexes of the magnesium phosphate cement-based synchronous grouting material prepared in this example, and the results are shown in the following table.

[0096]

[0097] Example 8

[0098] A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel is the same as that in the above-mentioned Example 3, except that the magnesium phosphate cement-based material in this example is prepared by the following method:

[0099] (1) The waste incineration fly ash and sulfuric acid with a mass fraction of 5% were mixed at a solid-liquid ratio of 1 g: 1.5 ml, and then left standing for 20 min, and then dried at 90 °C for 40 min to obtain pretreated fly ash. The pretreated fly ash and a potassium bicarbonate solution with a mass fraction of 10% were mixed at a ratio of 1 g: 2.0 ml and stirred evenly, and then dried at 60 °C for 80 min to obtain activated fly ash, which was reserved for use.

[0100] (2) Mix ammonium dihydrogen phosphate, zinc sulfate, and the activated fly ash prepared in this example evenly in a ratio of 45 parts by weight: 12 parts by weight: 15 parts by weight to form an acidic component. Mix the alkaline component prepared in Example 3 above and the acidic component prepared in this example evenly by stirring at a mass ratio of 5:1 to obtain a magnesium phosphate cement-based material.

[0101] Use the same method as in Example 1 above to test the performance indicators of the magnesium phosphate cement-based synchronous grouting material prepared in this example. The results are shown in the following table.

[0102]

[0103] It can be seen from the test results of the above examples that, compared with other examples, the magnesium phosphate cement-based synchronous grouting materials prepared in Example 1, Example 2, and Example 3 have better early strength, stability, and waterproof and erosion-resistant properties, thus being able to better improve the safety of the submarine tunnel during service.

[0104] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a magnesium phosphate cement-based synchronous grouting material for a subsea shield tunnel, characterized in that, It includes the following steps: (1) Mix metakaolin with a solution containing Mg 2+ evenly, and then add an alkaline solution and mix evenly; calcine the obtained metakaolin, and then grind the calcined product to obtain activated metakaolin; (2) Mix the waste incineration fly ash with phosphoric acid and then perform a drying treatment. Then, mix the obtained pretreated fly ash with the alkali solution evenly and perform a drying treatment again to obtain the activated fly ash; (3) Mix the activated metakaolin, the dead-burned magnesia powder, and the fly ash in a weight ratio of 25-40 parts: 60-90 parts: 30-50 parts to form an alkaline component for standby; mix the phosphate, the retarder, and the activated fly ash in a weight ratio of 20-45 parts: 4.5-12 parts: 5-15 parts to form an acidic component for standby; (4) Take the following raw materials: 150-200 parts by weight of the magnesium phosphate cement-based material, 50-80 parts by weight of the fine aggregate, 1-5 parts by weight of the fiber, 1-3 parts by weight of the toughening agent, 1-10 parts by weight of the stabilizer, 0.2-1 part by weight of the defoaming agent, 3-10 parts by weight of the water reducing agent, and 40-60 parts by weight of the mixing water. The magnesium phosphate cement-based material is formed by the alkaline component and the acidic component in a mass ratio of 3-5:1; mix the above raw materials evenly to obtain the magnesium phosphate cement-based synchronous grouting material.

2. The preparation method of the magnesium phosphate cement-based synchronous grouting material for the subsea shield tunnel according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the metakaolin to the Mg-containing 2+ solution is 1 g: 2 - 3.5 ml; the mass fraction of the Mg-containing 2+ solution is 10 - 20%.

3. The preparation method of the magnesium phosphate cement-based synchronous grouting material for the subsea shield tunnel according to claim 1, wherein, In step (1), the Mg-containing 2+ solution includes at least one of magnesium sulfate solution, magnesium nitrate solution, magnesium acetate solution, and magnesium bicarbonate solution.

4. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, characterized in that, In step (1), the OH provided by the lye - and the Mg 2+ have a molar ratio of 2.2 to 2.5:

1.

5. The preparation method of the magnesium phosphate cement-based synchronous grouting material for submarine shield tunnels according to claim 1, characterized in that, In step (1), the alkali solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia water.

6. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, characterized in that, In step (1), the calcination temperature is 550-700 °C and the time is 60-70 min.

7. The preparation method of the magnesium phosphate cement-based synchronous grouting material for submarine shield tunnels according to claim 1, characterized in that, In step (1), the fineness of the activated metakaolin is 200-300 mesh.

8. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, characterized in that, In step (2), the solid-liquid ratio of the waste incineration fly ash to phosphoric acid is 1 g: 1-1.5 ml, and the mass fraction of the phosphoric acid is 5-15%.

9. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, characterized in that, In step (2), the temperature of the drying treatment is 70-90 °C and the time is 40-50 min.

10. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, wherein, In step (2), the solid-liquid ratio of the pretreated fly ash to the alkali solution is 1 g: 1-2 ml, and the mass fraction of the alkali solution is 10-18%.

11. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, wherein, The alkali solution includes at least one of potassium hydroxide, potassium bicarbonate, and ammonium bicarbonate solution.

12. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, characterized in that, In step (2), the temperature of the second drying treatment is 40-60 °C and the time is 80-110 min.

13. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to claim 1, wherein, In step (3), the phosphate includes at least one of potassium dihydrogen phosphate and ammonium dihydrogen phosphate.

14. The preparation method of the magnesium phosphate cement-based synchronous grouting material for submarine shield tunnels according to claim 1, characterized in that In step (3), the retarder includes at least one of boric acid, borax, and zinc sulfate.

15. The preparation method of the magnesium phosphate cement-based synchronous grouting material for the subsea shield tunnel according to claim 1, characterized in that, In step (4), the stabilizer is formed by cellulose, nano-SiO2, triethanolamine, and water glass in a mass ratio of 0.1-0.5: 1-5: 0.1-0.5: 0.05-0.

5.

16. The preparation method of the magnesium phosphate cement-based synchronous grouting material for submarine shield tunnels according to claim 15, characterized in that, The cellulose includes at least one of hydroxypropyl methylcellulose, hydroxymethylcellulose, and hydroxypropylcellulose.

17. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to any one of claims 1-16, characterized in that, In step (4), the toughening agent includes at least one of ethylene / vinyl acetate copolymer rubber powder and styrene-butadiene rubber powder.

18. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to any one of claims 1-16, characterized in that, In step (4), the fiber includes at least one of carbon fiber, polyvinyl alcohol fiber, polyethylene fiber, and polypropylene fiber.

19. The preparation method of the magnesium phosphate cement-based synchronous grouting material for subsea shield tunnels according to any one of claims 1-16, characterized in that, In step (4), the length of the fiber is 2-4 mm and the diameter is 5-10 μm.

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