High-performance shield support mud, preparation method and application thereof

Abstract

The application provides a high-performance shield support mud and a preparation method and application thereof, and comprises A component, B component and C component materials, the A component comprises the following raw materials: modified calcium bentonite 60-70 parts, quartz sand 25-35 parts, SMAS-AA-St block copolymer dispersant 0.1-0.3 parts, curing aid 5-8 parts; the B component is a polymer emulsion with a mass concentration of 2-5%, and the C component is water glass with a Baume degree of 35-45. Compared with the prior art, the components of the application are synergistic with each other, have a low initial viscosity, and the support mud after solidification has excellent waterproofness and high shear strength. In the shield construction, the shield support mud can play a good supporting role when encountering seepage water and sandstone soft rock zones, is not easy to be diluted by water, has certain water blocking and lubricating properties, can well prevent water gushing, ground subsidence and shield machine planting head and the like, and improves the safety protection performance.

Description

Technical Field

[0001] This invention belongs to the field of shield tunneling engineering materials, specifically relating to a high-performance shield support mud, its preparation method, and its application, which can be widely used in shield tunneling construction. Background Technology

[0002] With the rapid development of urbanization and the increasing number of infrastructure projects such as subways, underground utility tunnels, and water diversion tunnels, shield tunneling is being used more and more widely.

[0003] The shield tunneling method uses a tunnel boring machine (TBM) to excavate and advance, and then lining the tunnel at the tail end to construct a tunnel. It is a fully mechanized construction method belonging to the cut-and-cover method, suitable for constructing tunnels in soft aquifers, especially under rivers, seabeds, and urban centers. The head excavates the foundation layer, while the tail rapidly assembles the permanent tunnel lining. The entire process is automated, reducing the labor intensity of workers, offering fast excavation speeds, and high safety, making it a promising field in underground engineering.

[0004] However, during tunnel boring machine (TBM) construction, it is inevitable to encounter soft rock and water seepage areas. Since the diameter of the TBM cutterhead is larger than the diameter of the shield body, the diameter of the hole formed after the cutterhead excavates is larger than the diameter of the shield body behind it. This creates a cavity around the shield body. If the soil has poor bearing capacity and the cavity is not filled with filler material in time, it can easily cause ground subsidence, resulting in serious safety accidents such as ground collapse, building collapse, and underground pipeline rupture.

[0005] Therefore, during tunnel boring machine (TBM) construction, a filling material is typically pumped into the cavity using the TBM's pumping equipment. However, commonly used sodium-based or calcium-based bentonite slurries have poor load-bearing capacity and insufficient waterproofing. While water-hardening materials such as cement slurry, which offer better load-bearing capacity and waterproofing, can be rapidly hardened by adding accelerators to achieve the desired support, the resulting cement paste can cause severe wear on the cutting tools and the shield. Therefore, there is an urgent need to develop a TBM support mud that not only has high load-bearing capacity and good waterproofing but also does not harden. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance shield tunneling support mud and its preparation method. It adopts a novel three-component support mud, and the mixed shield tunneling support mud has high support force and shear strength, and does not solidify or harden. When the shield tunneling machine encounters water seepage and soft rock areas such as sandstone, the shield tunneling support mud can play a good supporting role. It is not easily diluted by water, has certain water-blocking and lubricating properties, and can effectively prevent water inrush, ground subsidence, and shield machine head collapse, thereby improving safety performance.

[0007] Another objective of this invention is to provide an application of high-performance shield support mud for shield tunneling construction, especially for shield tunneling projects such as subways, underground utility tunnels, and tunnel water diversion.

[0008] The specific technical solution of this invention is as follows:

[0009] A high-performance shield tunneling support mud, comprising components A, B, and C;

[0010] Component A includes the following raw materials:

[0011]

[0012] In component A:

[0013] The modified calcium-based bentonite has a particle size of 200-325 mesh. The mesh size of the bentonite ensures its reactivity with water glass. If the mesh size is too coarse, the specific surface area is low and the reactivity is poor. If the mesh size is too fine, dispersion is difficult and the initial slurry viscosity is high.

[0014] The modification process of the modified calcium-based bentonite is as follows: calcining the calcium-based bentonite at 150-200℃ for 1±0.2h;

[0015] The quartz sand is 100-120 mesh quartz sand; if the quartz sand particle size is too large, it will precipitate in the initial slurry, so it is necessary to control the quartz sand to be 100-120 mesh quartz sand.

[0016] The preparation method of the SMAS-AA-St block copolymer dispersant includes the following steps:

[0017] 1) Mix sodium methallyl sulfonate and water, heat to a certain temperature, and add oxidizing agent and chain transfer agent as a base material;

[0018] 2) Add acrylic acid solution and reducing agent solution to the base material simultaneously. After adding all the solution, keep the material warm.

[0019] 3) Maintain the heat preservation conditions, then add the oxidant, stir, and simultaneously add styrene and reducing agent solutions dropwise. After the addition is complete, maintain the heat preservation.

[0020] 4) Add alkali to adjust the pH to 7-8 to obtain SMAS-AA-St block copolymer dispersant.

[0021] Sodium methyl methacrylate (SMAS) is abbreviated as SMAS, acrylic acid is abbreviated as AA, and styrene is abbreviated as St.

[0022] The mass ratio of acrylic acid and styrene in the sodium methacrylate sulfonate and acrylic acid solution is 4.5-5.5:20-25:5-10;

[0023] The mass ratio of sodium methacrylate sulfonate, water, oxidant and chain transfer agent in step 1) is 4.5-5.5: 40-50: 0.5-2.5: 0-0.05;

[0024] The oxidant mentioned in steps 1) and 3) is hydrogen peroxide, i.e., an aqueous solution of hydrogen peroxide, with a mass concentration of 27.5%.

[0025] The heating mentioned in step 1) refers to heating to 35-55℃ under stirring conditions;

[0026] The chain transfer agent mentioned in step 1) is 3-mercaptopropionic acid;

[0027] In step 2), the mass ratio of acrylic acid in the acrylic acid solution to reducing agent in the reducing agent solution is 20-25: 0.045-0.08;

[0028] Step 2) The acrylic solution is obtained by mixing 20-25 parts by weight of acrylic acid and 10-15 parts by weight of water until homogeneous;

[0029] The reducing agent mentioned in steps 2) and 3) is sodium dioctyl sulfosuccinate E51;

[0030] In step 2), the reducing agent solution refers to the solution obtained by mixing 0.045-0.08 parts of reducing agent and 5-10 parts of water by mass until homogeneous.

[0031] In step 2), the acrylic acid solution is dripped over 2-2.5 hours, and the reducing agent solution is dripped over 2.5-3.0 hours; the reducing agent solution dripping time is 0.5 hours longer than the acrylic acid solution dripping time; after the dripping is completed, the solution is kept warm for 25-35 minutes.

[0032] In step 3), the mass ratio of the reducing agent in the oxidizing agent, styrene, and reducing agent solution is: 0.3-1.0 : 5-10 : 0.025-0.035;

[0033] The reducing agent solution in step 3) refers to the solution obtained by mixing 0.025-0.035 parts of reducing agent and 5-10 parts of water by mass until homogeneous.

[0034] In step 3), the styrene is added over 1-1.5 hours, and the reducing agent solution is added over 1.5-2.0 hours; the reducing agent solution takes 0.5 hours longer to add than the styrene; after the addition is complete, the solution is kept warm for 2 ± 0.1 hours.

[0035] In step 4), the alkali is a sodium hydroxide solution with a concentration of 30%-40%;

[0036] In step 4), a SMAS-AA-St block copolymer dispersant liquid with a solid content of 30-40% is prepared; as needed, a powdered SMAS-AA-St block copolymer dispersant is prepared by spray drying.

[0037] The general chemical structural formula of the SMAS-AA-St block copolymer dispersant is:

[0038]

[0039] The curing aid is one of calcium chloride, barium chloride, potassium aluminum sulfate, barium hydroxide, sodium fluorosilicate, and silicon phosphate.

[0040] Component B is a polymer emulsion with a mass concentration of 2-5%;

[0041] The polymer emulsion is one of pure acrylic emulsion, silicone acrylic emulsion, polyurethane emulsion, or styrene acrylic emulsion.

[0042] The C component is water glass with a Baume degree of 35-45.

[0043] The mass ratio of components A, B, and C is 1:2.0-3.0:0.1-0.25.

[0044] This invention provides a method for preparing high-performance shield tunneling support mud, comprising the following steps:

[0045] After mixing the raw materials of component A in the formula evenly, add the raw materials of component B in the formula evenly, stir evenly, then add component C under stirring conditions and stir quickly to obtain the final product.

[0046] The addition time for component B should be controlled at 1-3 min; the addition time for component C should be controlled at 10-30 s.

[0047] The term "uniform mixing" refers to mixing for 5-10 minutes with a mixing speed of ≥80 rpm.

[0048] The rapid stirring time is 9-11 seconds.

[0049] This invention provides an application of high-performance shield tunneling support mud for shield tunneling projects, especially for shield tunneling projects such as subways, underground utility tunnels, and tunnel water diversion projects.

[0050] The application method is as follows:

[0051] S1. The modified calcium-based bentonite, quartz sand, SMAS-AA-St block copolymer dispersant, and curing aid are placed in a dry mixing equipment and stirred evenly to obtain component A.

[0052] S2. Place component A in a mixing device, turn on the mixing, slowly add the amount of component B in the formula to component A, and stir for 5-10 minutes to obtain a flowable uniform slurry (1).

[0053] S3. Component C and mud (1) are simultaneously injected into the outside of the tunnel boring machine through the grouting pump and the mixer on the tunnel boring machine via the grouting hole to fill the gap around the tunnel boring machine.

[0054] To achieve good support strength and waterproofing performance in the supporting mud, this invention employs a multi-component synergistic effect to achieve both support and waterproofing. Ordinary calcium-based or sodium-based bentonite reacts slowly with water glass, resulting in a solidified material with low support strength. Therefore, this invention uses high-temperature activated and modified calcium-based bentonite. Firing natural bentonite at different temperatures can sequentially remove surface adsorbed water, interlayer water, and structural water. However, excessively high temperatures can make the bentonite too hydrophobic and porous, increasing water demand and reducing initial fluidity. Furthermore, when the baking temperature exceeds 600℃, the high temperature can damage the bentonite structure, significantly altering its properties. Therefore, this invention controls the baking temperature of bentonite at 150-200℃, causing the bentonite to lose some of the surface adsorbed water and interlayer water in its structural channels without changing its crystalline structure, thus appropriately increasing the specific surface area and ultimately... The increased reactivity of bentonite with water glass significantly improved the reaction rate and the supporting strength of the solidified material. However, due to the strong water molecule adsorption capacity of the interlayer structure of montmorillonite crystals, and the increased specific surface area of ​​the modified bentonite, the amount of water adsorbed when mixed with water was greater, resulting in poorer initial slurry fluidity. To ensure the slurry composed of components A and B can be smoothly injected into the outside of the tunnel boring machine (TBM) through the grouting pump and the mixer on the TBM via the grouting holes, the slurry needs to have low viscosity, i.e., good fluidity. Therefore, to achieve better initial slurry fluidity, this invention employs a linear SMAS-AA-St copolymer polycarboxylate dispersant, which has better dispersibility than common inorganic dispersants such as sodium tripolyphosphate and sodium hexametaphosphate, ensuring a low initial slurry viscosity that can be smoothly pumped into the cavity created by the TBM. Electrostatic repulsion and steric hindrance are the two main effects of dispersants on particle dispersion. Both effects depend on the adsorption of dispersant molecules onto the particle surface. Commonly available comb-type polycarboxylate dispersants, due to their short main chains and numerous long branches, exhibit weak adsorption to layered bentonite particles, resulting in minimal impact on the zeta potential of colloidal particles in bentonite slurry and insignificant dispersion. In contrast, linear SMAS-AA-St copolymer polycarboxylate dispersants, with their longer main chains, can firmly adsorb onto the surface of lamellar bentonite particles through line-to-surface bonding. This achieves electrostatic repulsion and steric hindrance, effectively dispersing the flocculated state of bentonite, releasing free water, and improving fluidity. The SMAS-AA-St copolymer polycarboxylic acid dispersant contains a large number of anionic carboxylic acid groups introduced by AA, which can interact with the cationic groups on the surface of bentonite, so that the dispersant is firmly adsorbed on the bentonite particles. In order to improve the dispersion effect, SMAS is introduced in this invention. SMAS not only provides strong polar anionic sulfonic acid groups to improve electrostatic repulsion, but also acts as a chain transfer agent, making the molecular weight of the synthesized dispersant more uniform.Simultaneously, the introduction of a styrene hydrophobic structure into the dispersant molecule enhances its affinity with the polymer in component B of this invention, and also improves its hydrophobicity after the bentonite reacts and solidifies with component C, the curing agent. However, commonly used random copolymers exhibit irregular distribution of hydrophilic and hydrophobic structures, failing to achieve synergistic effects and even interfering with each other, thus affecting dispersion ability. Therefore, from the perspective of polymer molecular structure, the use of a block copolymer structure, with its separated hydrophilic and hydrophobic structures and multiple anchoring groups positioned close to each other, allows for better interaction with colloidal particles in the bentonite slurry, resulting in tight and persistent adsorption and preventing dispersant molecule desorption, which is highly beneficial for the dispersant effect. Furthermore, styrene, as a hydrophobic monomer, also enhances its affinity with the polymer in component B of this invention. Therefore, this invention employs a sequential feeding method to prepare a block copolymer amphiphilic dispersant. To achieve superior support strength in the support mud, 100-120 mesh quartz sand was added as coarse aggregate, along with a curing agent to allow the water glass and bentonite to react more fully, forming a support structure with good load-bearing capacity. At the same time, a polymer emulsion with excellent waterproof properties was used to further improve the waterproofness of the support mud, thereby enhancing the safety performance of shield tunneling.

[0055] Compared with existing technologies, the high-performance novel shield tunneling support mud provided by this invention is made of three components, has a low initial viscosity, and incorporates a polymer emulsion with good waterproof properties, giving the solidified support mud superior waterproof properties and higher shear strength. When used in shield tunneling in areas with seepage water or soft sandstone and rock, this shield tunneling support mud can provide good support. Furthermore, it is not easily diluted by water and has certain water-blocking and lubricating properties, which can effectively prevent water inrush, surface subsidence, and shield machine head collapse, thereby improving safety performance. Attached Figure Description

[0056] Figure 1 This is a diagram showing the state of high-performance new shield tunneling mud after solidification.

[0057] Figure 2 This is a schematic diagram illustrating the load-bearing capacity of high-performance new shield tunneling mud after solidification. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0059] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0060] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0061] Examples 1-4

[0062] A high-performance shield tunneling support mud comprises the following raw materials in parts by weight, as shown in Table 1.

[0063] Comparative Examples 1-7

[0064] A high-performance shield tunneling support mud comprises the following raw materials in parts by weight, as shown in Table 1.

[0065] Table 1. Raw materials and parts by weight for each embodiment and comparative example.

[0066]

[0067] The performance and specifications of the raw materials in each embodiment and comparative example are as follows:

[0068] The calcium-based bentonite has a particle size of 300 mesh. The modified calcium-based bentonite of Examples 1-2 and Comparative Examples 2-3 was baked at 150°C for 1 hour, and the modified calcium-based bentonite of Examples 3-4 and Comparative Examples 4-5 was baked at 200°C for 1 hour. The calcium-based bentonite used in Comparative Example 1 had a particle size of 300 mesh and was baked at 600℃ for 1 hour.

[0069] The curing aid is one of calcium chloride, barium chloride, potassium aluminum sulfate, barium hydroxide, sodium fluorosilicate, and silicon phosphate; wherein the curing aid in Example 1, Comparative Examples 1-2, and Comparative Examples 6 is calcium chloride; the curing aid in Example 2 and Comparative Example 3 is potassium aluminum sulfate; and the curing aid in Example 3-4 and Comparative Examples 4-5 is sodium fluorosilicate.

[0070] The concentration of component B in Examples 1-2 and Comparative Examples 1-2 was 2%; the concentration of component B in Examples 3-4, Comparative Examples 3, and Comparative Examples 5-6 was 5%.

[0071] The preparation method of the SMAS-AA-St block copolymer dispersant used in Example 1 is as follows:

[0072] 1) Mix 4.5 parts by weight of sodium methacrylate sulfonate (SMAS) and 50 parts by weight of water, stir and heat to 35°C;

[0073] 2) Mix 25 parts by weight of acrylic acid AA and 15 parts by weight of water until homogeneous to form solution A;

[0074] 3) 10 parts by weight of styrene St is solution B;

[0075] 4) Mix 0.08 parts by weight of reducing agent E51 and 10 parts by weight of water until homogeneous to obtain solution C;

[0076] 5) Mix 0.025 parts by weight of reducing agent E51 and 5 parts by weight of water until homogeneous to obtain solution D;

[0077] 6) After the system in step 1) is heated to 35°C, add 2.5 parts by weight of 27.5% hydrogen peroxide and 0.05 parts by weight of 3-mercaptopropionic acid. After stirring for 5 minutes, start adding solution A and solution C dropwise. Solution A is added over 2 hours and solution C is added over 2.5 hours. After the addition is complete, keep the system at 35°C for 0.5 hours.

[0078] 7) Keep warm at 35℃, add 0.3 parts by weight of hydrogen peroxide to the reaction solution in step 6), stir for 5 minutes and then start adding solution B and solution D dropwise. Control the addition of solution B to be completed in 1 hour and solution D to be completed in 1.5 hours; keep warm for 2 hours after the addition is completed.

[0079] 8) Neutralize with 12 parts by weight of 30% sodium hydroxide solution to pH 7 to obtain SMAS-AA-St block copolymer dispersant with a solid content of 35%.

[0080] 9) The liquid SMAS-AA-St block copolymer dispersant prepared in step 8) is spray-dried to obtain a powder dispersant.

[0081] The preparation method of the SMAS-AA-St block copolymer dispersant used in Example 2 is as follows:

[0082] 1) Mix 5.5 parts by weight of sodium methacrylate sulfonate (SMAS) and 40 parts by weight of water, stir and heat to 55°C;

[0083] 2) Mix 20 parts by weight of acrylic acid AA and 10 parts by weight of water until homogeneous to form solution A;

[0084] 3) Prepare solution B using 5 parts by weight of styrene St;

[0085] 4) Mix 0.045 parts by weight of reducing agent E51 and 5 parts by weight of water until homogeneous to obtain solution C;

[0086] 5) Mix 0.035 parts by weight of reducing agent E51 and 10 parts by weight of water until homogeneous to obtain solution D;

[0087] 6) After the system in step 1) is heated to 55°C, add 0.5 parts by weight of 27.5% hydrogen peroxide. After stirring for 10 minutes, start adding solution A and solution C dropwise. Solution A is added over 2.5 hours, and solution C is added over 3.0 hours. After the addition is complete, keep the system at 55°C for 0.5 hours.

[0088] 7) At 55℃, add 1.0 part by weight of hydrogen peroxide to the reaction solution in step 6), stir for 10 min, and then start adding solution B and solution D dropwise. Solution B is added over 1.5 h and solution D is added over 2.0 h. After the addition is complete, keep warm for 2 hours.

[0089] 8) Neutralize with 15 parts by weight of 30% sodium hydroxide solution to pH 8 to obtain SMAS-AA-St block copolymer dispersant with a solid content of 37%.

[0090] 9) The 37% SMAS-AA-St block copolymer dispersant prepared in step 8) was spray-dried to obtain a powder dispersant.

[0091] The preparation method of the SMAS-AA-St block copolymer dispersant used in Example 3 is as follows:

[0092] 1) Mix 5.0 parts by weight of sodium methacrylate sulfonate (SMAS) and 45 parts by weight of water, stir and heat to 45°C;

[0093] 2) Mix 23 parts by weight of acrylic acid AA and 13 parts by weight of water until homogeneous to form solution A;

[0094] 3) 8 parts by weight of styrene St is solution B;

[0095] 4) Mix 0.06 parts by weight of reducing agent E51 and 8 parts by weight of water until homogeneous to obtain solution C;

[0096] 5) Mix 0.03 parts by weight of reducing agent E51 and 8 parts by weight of water until homogeneous to obtain solution D;

[0097] 6) After the system in step 1) is heated to 45°C, add 1.5 parts by weight of hydrogen peroxide and 0.03 parts by weight of 3-mercaptopropionic acid. After stirring for 8 minutes, start adding solution A and solution C dropwise. Solution A is added over 2 hours, and solution C is added over 2.5 hours. After the addition is complete, keep the system at 45°C for 0.5 hours.

[0098] 7) At 45℃, add 0.5 parts by weight of hydrogen peroxide to the reaction solution in step 6), stir for 8 minutes, and then start adding solution B and solution D dropwise. Solution B is added over 1 hour and solution D is added over 1.5 hours. After the addition is completed, keep warm for 2 hours.

[0099] 8) Neutralize with 13 parts by weight of 30% sodium hydroxide solution to pH 8 to obtain SMAS-AA-St block copolymer dispersant with a solid content of 36%.

[0100] 9) The liquid SMAS-AA-St block copolymer dispersant prepared in step 8) is spray-dried to obtain a powder dispersant.

[0101] The SMAS-AA-St block copolymer dispersant used in Example 4 is the same as that used in Example 3.

[0102] The preparation method of the SMAS-AA-St random copolymer dispersant used in Comparative Example 3 is as follows:

[0103] 1) Mix 5.0 parts by weight of sodium methacrylate sulfonate (SMAS) and 45 parts by weight of water, stir and heat to 45°C;

[0104] 2) Mix 23 parts by weight of acrylic acid AA and 13 parts by weight of water until homogeneous to form solution A;

[0105] 3) 8 parts by weight of styrene St is solution B;

[0106] 4) 0.09 parts by weight Reducing agent E51 and 16 parts by weight The water is stirred until homogeneous, resulting in solution C;

[0107] 6) After the system in step 1) is heated to 45°C, add 2.0 parts by weight of hydrogen peroxide and 0.03 parts by weight of 3-mercaptopropionic acid. After stirring for 8 minutes, start adding solutions A, B and C dropwise. Solutions A and B are added over 2 hours, and solution C is added over 2.5 hours. After the addition is complete, keep the system at this temperature for 2 hours.

[0108] 7) Neutralize to pH 8 with 13 parts by weight of 30% sodium hydroxide solution to obtain SMAS-AA-St with a solid content of 36%. Random copolymer dispersants .

[0109] 8) The liquid SMAS-AA-St block copolymer dispersant prepared in step 7) is spray-dried to obtain a powder dispersant.

[0110] The SMAS-AA-St block copolymer dispersant used in Comparative Examples 4-5 was the same as that used in Example 3.

[0111] The SMAS-AA-St block copolymer dispersant used in Comparative Examples 1 and 6 was the same as that used in Example 1.

[0112] The methods for preparing the support mud in each embodiment and comparative example are as follows:

[0113] S1. According to the formula, place the modified calcium-based bentonite, quartz sand, SMAS-AA-St block copolymer dispersant and curing aid into a dry mixing equipment and mix evenly to obtain premixed component A;

[0114] S2. Place the obtained premixed component A into the mixing equipment, turn on the mixing, add the formula amount of component B to component A, control the addition time of component B to 2 minutes, stir for 5 minutes, and obtain a flowable uniform mud slurry (1); the viscosity of mud slurry (1) will affect the shield tunneling construction. If it is too sticky, it will not be conducive to long-distance transportation. If it is too thin, it will settle and harden at the bottom, which will also not be conducive to transportation.

[0115] S3. Slowly add component C to the mud (1), control the addition time of component C to 20s, and stir quickly for 10s to obtain high-performance shield support mud.

[0116] The performance of the high-performance shield tunneling support mud prepared in the examples and comparative examples is shown in Table 2. The viscosity was tested using a rotational viscometer, and the shear strength was tested using a direct shear tester. The water resistance test and evaluation criteria were as follows: the support mud was impacted with a water flow of 0.2 MPa. If the support mud did not disperse, the water resistance was excellent; if the support mud dispersed but did not mix with the water, the water resistance was good; and if the support mud dispersed and mixed with the water, the water resistance was poor.

[0117] Table 2. Performance of the high-performance novel shield tunneling support mud prepared in each embodiment and comparative example.

[0118]

[0119]

[0120] The items underlined above do not meet the requirements of this invention.

[0121] The data above shows that the supporting mud provided in Examples 1-4 utilizes the multi-component synergistic effect designed in this invention. This not only gives the mud (1) a lower initial viscosity, facilitating pumping, but also introduces a polymer emulsion with good waterproof properties. The supporting mud, after solidification with water glass, exhibits higher viscosity and shear strength, resulting in superior load-bearing capacity and waterproofing (e.g., ...). Figures 1-2When encountering water seepage and soft rock areas during tunnel boring machine (TBM) construction, this TBM support mud provides excellent support and waterproofing, preventing water inrush, surface subsidence, and TBM head collapse, thus improving safety performance. In contrast, the bentonite in Comparative Example 1, after high-temperature baking, undergoes structural changes, becoming excessively hydrophobic and porous, increasing water demand, reducing initial fluidity, and losing its reactivity with water glass, resulting in low viscosity and poor shear strength in the support mud. Comparative Example 2 used comb-type polycarboxylate dispersant, a commonly used organic dispersant in cement concrete. However, due to the significant differences in the composition and crystal structure of bentonite compared to cement, and the fact that bentonite is a mineral with montmorillonite as its main component, and that the interlayer of the montmorillonite crystal structure has a very strong ability to adsorb water molecules, the dispersant effect was poor, and the viscosity of the mud (1) was high, affecting the pumping efficiency. Comb-type polycarboxylate dispersant, due to its short main chain and numerous and long branches, mostly bonded to the layered bentonite particles with a weak adsorption, and had little effect on the ζ-potential of colloidal particles in the bentonite mud, resulting in an insignificant dispersion effect. Furthermore, due to the poor dispersion effect, there was agglomeration among the bentonite particles, leading to poor reactivity with water glass and low viscosity and shear strength of the solidified support mud. Comparative Example 3 used a linear random copolymer dispersant, with the same component ratio as in Example 3, but the dispersion effect was significantly worse than in Example 3, and the viscosity of the mud (1) was slightly higher. In Comparative Example 4, the polymer emulsion of component B was replaced with water, resulting in a slight decrease in water resistance. In Comparative Example 5, the absence of added quartz sand reduced the supporting strength, and the initial viscosity also increased slightly due to the greater water adsorption capacity of the bentonite. Comparative Example 6 used unmodified commercially available calcium-based bentonite, resulting in a lower initial viscosity of the slurry (1), but poor reactivity with water glass, leading to lower viscosity and shear strength of the solidified supporting mud. Comparative Example 7 used only calcium-based bentonite and water to prepare the slurry, which was then solidified with water glass. The initial viscosity was high, but the viscosity and shear strength were low after solidification, indicating poor water resistance.

[0122] The components of this invention work synergistically to give it a lower initial viscosity. The solidified support mud has better waterproof properties and higher shear strength. When used in shield tunneling in areas with water leakage or sandstone and soft rock, this shield support mud can provide good support. It is not easily diluted by water and has certain water-blocking and lubricating properties, which can effectively prevent water inrush, ground subsidence, and shield machine head collapse, thereby improving safety performance.

[0123] While this application has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of this application. Furthermore, various modifications can be made to the subject, spirit, and scope of this application to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of this application.

Claims

1. A high-performance shield tunneling support mud, characterized in that, The high-performance shield tunneling support mud comprises components A, B, and C. Component A includes the following raw materials: The modification process of the modified calcium-based bentonite is as follows: calcining the calcium-based bentonite at 150-200℃ for 1±0.2h; Component B is a polymer emulsion with a mass concentration of 2-5%; The C component is water glass with a Baume degree of 35-45; The preparation method of the SMAS-AA-St block copolymer dispersant includes the following steps: 1) Mix sodium methallyl sulfonate and water, heat to a certain temperature, and add oxidizing agent and chain transfer agent as a base material; 2) Add acrylic acid solution and reducing agent solution to the base material simultaneously. After adding all the solution, keep the material warm. 3) Add the oxidizing agent, stir, and then simultaneously add styrene and reducing agent solutions dropwise. After the addition is complete, keep the mixture warm. 4) Add alkali to adjust the pH to 7-8; this yields the SMAS-AA-St block copolymer dispersant. The mass ratio of acrylic acid and styrene in the sodium methacrylate sulfonate and acrylic acid solution is 4.5-5.5:20-25:5-10; The polymer emulsion is one of pure acrylic emulsion, silicone acrylic emulsion, polyurethane emulsion, or styrene acrylic emulsion.

2. The high-performance shield tunneling support mud according to claim 1, characterized in that, The mass ratio of sodium methacrylate sulfonate, water, oxidant and chain transfer agent in step 1) is 4.5-5.5: 40-50: 0.5-2.5: 0-0.

05.

3. The high-performance shield tunneling support mud according to claim 1, characterized in that, The heating mentioned in step 1) refers to heating to 35-55℃.

4. The high-performance shield tunneling support mud according to claim 1, characterized in that, In step 2), the mass ratio of acrylic acid in the acrylic acid solution to reducing agent in the reducing agent solution is 20-25: 0.045-0.

08.

5. The high-performance shield tunneling support mud according to claim 1, characterized in that, In step 3), the mass ratio of the oxidant, styrene and reducing agent in the reducing agent solution is: 0.3-1.0: 5-10: 0.025-0.

035.

6. The high-performance shield tunneling support mud according to claim 1 or 2, characterized in that, The mass ratio of components A, B, and C is 1:2.0-3.0:0.1-0.

25.

7. A method for preparing high-performance shield tunneling support mud according to any one of claims 1-6, characterized in that, The preparation method is as follows: after mixing the raw materials of component A in the formula evenly, slowly add the raw materials of component B in the formula evenly, stir evenly, and then slowly add component C under stirring conditions, and stir rapidly to obtain the final product.

8. The application of the high-performance shield tunneling support mud according to any one of claims 1-6, characterized in that, Used in shield tunneling projects.

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