Soil dispersant for shield construction and preparation method thereof

Abstract

The application discloses a soil dispersing agent for shield construction and a preparation method thereof. The soil dispersing agent is composed of a compound A and sulfonated succinic acid di-zinc ester sodium. The structural formula of the compound A is shown in the description. The soil dispersing agent is prepared by compounding two components. One is a non-polar hydrophilic group with negative charge, and the other is an oleophilic carbon hydrogen chain. The soil dispersing agent can promote wetting modification, reduce interfacial tension and enhance electrostatic force, improve the space steric hindrance effect, reduce apparent viscosity and improve dispersing effect.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and specifically to a soil dispersant for tunnel boring machine (TBM) construction and its preparation method. Background Technology

[0002] When tunnel boring machines (TBMs) are constructed in certain complex geological formations, especially in water-rich sandy layers and complex strata, they encounter a series of problems such as mudslides, sand inrushes, crusting, and blockages. These problems cause difficulties in advancement, severe cutter wear, and even engineering accidents such as tunnel collapse and ground subsidence. The most effective way to solve these problems is to improve the soil. Among the commonly used soil conditioners, foaming agents are the most advanced to date. TBM foaming agents are compounded from surfactants, stabilizers, reinforcing agents, and dispersants, with water as the carrier. In TBM construction, foamed soil conditioners are prepared by mixing foaming agents with water in a certain proportion to obtain a foaming agent solution.

[0003] The dispersant is mainly composed of surfactants and powerful penetrants. Through penetration, the molecules of the shield mudstone dispersant quickly enter the soil, rapidly dispersing and separating large pieces of soil. It can quickly and powerfully peel off and remove mud clumps, making the drill bit or the inner surface of the pipe clean and solving problems such as mud cake on the shield machine cutterhead.

[0004] Research on foaming agents and penetrants in my country is currently in its early stages, with immature technology and reliance on imports. Existing patents cover dispersants with generally poor performance, offering limited effectiveness in dispersing clay; their formulations are complex, difficult to prepare, and detrimental to production. Summary of the Invention

[0005] The purpose of this invention is to address the problems of unsatisfactory practical effects and complex formulation of existing soil dispersants by providing a soil dispersant for shield tunneling and its preparation method.

[0006] To achieve the above objectives, the present invention provides a soil dispersant for shield tunneling construction, which is composed of compound A and sodium dioctyl sulfosuccinate, wherein the structural formula of compound A is:

[0007]

[0008] Optionally, compound A is prepared by esterification of sodium hydroxyethyl sulfonate and oxalic acid.

[0009] Optionally, the raw materials of the soil dispersant, by weight, include:

[0010]

[0011] The present invention also provides a method for preparing the above-mentioned soil dispersant for shield tunneling construction, comprising:

[0012] Step 1: Using oxalic acid and sodium hydroxyethyl sulfonate as raw materials and concentrated sulfuric acid as a catalyst, compound A is prepared;

[0013] Step 2: After the reaction in Step 1 is complete, adjust the pH to weakly alkaline, separate and purify to obtain compound A;

[0014] Step 3: Compound A is compounded with sodium dioctyl sulfosuccinate to obtain a soil dispersant.

[0015] Optionally, in step two, sodium hydroxide is added to adjust the pH to a slightly alkaline state.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention addresses the problems of unsatisfactory performance and complex formulation of existing soil dispersants by providing a soil dispersant for tunnel boring machine (TBM) construction and its preparation method. Based on sodium dioctyl sulfonate (T50), a high-performance dispersant is prepared by compounding it with a penetrating component made from sodium hydroxyethyl sulfonate and oxalic acid in a certain proportion. The two components exhibit a synergistic effect, improving the dispersion performance.

[0018] The dispersant of this invention can adsorb onto the surface of solid particles, reducing the surface tension between the solid and liquid, and making the surface of the aggregated solid particles easier to wet. Through the action of electrostatics, van der Waals forces, or hydrogen bonds on the particle clusters, the dispersant causes the particle clusters to permeate with water, generating osmotic pressure, reducing the adhesion between particle clusters and the mechanical effort required for breakage, thereby gradually achieving the dispersing effect of the dispersant on the particle clusters. A bilayer structure is formed on the surface of the solid particles; the polar end of the outer layer of the dispersant has a strong affinity for water, increasing the degree to which the solid particles are wetted by water, while the solid particles are separated by electrostatic repulsion.

[0019] The preparation process of this invention is simple, and it has good dispersibility, permeability, and foaming properties, and has low metal corrosivity. It can effectively improve the problem of mud cake formation on the cutterhead of tunnel boring machines and improve construction efficiency. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below. 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.

[0021] This invention prepares a permeation component raw material A by reacting sodium hydroxyethyl sulfonate with oxalate esterification, and then combines it with sodium dioctyl sulfosuccinate (T50) to form a high-performance dispersant.

[0022]

[0023] The main raw materials of this invention, by weight, are as follows:

[0024]

[0025] Preparation steps:

[0026] Oxalic acid and sodium hydroxyethyl sulfonate, weighed in a specific molar ratio, are added to a three-necked flask equipped with a thermometer, a nitrogen protection device, and a condenser. Concentrated sulfuric acid is added as a catalyst, and the mixture is heated to a specified time using a magnetic stirring program before stopping the heating.

[0027] After the reaction is complete, allow it to cool naturally, add sodium hydroxide, control the pH to be slightly alkaline, and separate and purify the crude product to finally obtain the desired dispersant component A.

[0028] The final shield tunneling dispersant is obtained by compounding T50 and dispersant component A in a certain proportion. Adding a foaming agent can prepare a dispersible foaming agent. The foaming agent of this invention is a commercially available conventional foaming agent.

[0029] Example 1

[0030] Raw material formula, by mass parts:

[0031] 40 parts of T50 (sodium dioctyl sulfosuccinate)

[0032] 25 parts of sodium hydroxyethyl sulfonate

[0033] 12 parts oxalic acid

[0034] 1 part concentrated sulfuric acid

[0035] 2 parts sodium hydroxide

[0036] Preparation steps:

[0037] 1. Add oxalic acid and sodium hydroxyethyl sulfonate weighed in a certain molar ratio to a three-necked flask equipped with a thermometer, nitrogen protection device and condenser, add concentrated sulfuric acid as a catalyst, and heat up to the specified time by magnetic stirring and then stop heating.

[0038] 2. After the reaction is complete, allow it to cool naturally, add sodium hydroxide, control the pH to be slightly alkaline, and separate and purify the crude product to finally obtain the desired dispersant component A.

[0039] 3. The final shield tunneling dispersant is obtained by compounding T50 and dispersant component A in a certain proportion, and the pH is controlled at a weakly acidic level.

[0040] Example 2

[0041] Raw material formula, by mass parts:

[0042]

[0043] Preparation steps:

[0044] 1. Add oxalic acid and sodium hydroxyethyl sulfonate weighed in a certain molar ratio to a three-necked flask equipped with a thermometer, nitrogen protection device and condenser, add concentrated sulfuric acid as a catalyst, and heat up to the specified time by magnetic stirring and then stop heating.

[0045] 2. After the reaction is complete, allow it to cool naturally, add sodium hydroxide, control the pH to be slightly alkaline, and separate and purify the crude product to finally obtain the desired dispersant component A.

[0046] 3. The final shield tunneling dispersant is obtained by compounding T50 and dispersant component A in a certain proportion, and the pH is controlled at a weakly acidic level.

[0047] Example 3

[0048] By mass parts

[0049]

[0050] Preparation steps:

[0051] 1. Add oxalic acid and sodium hydroxyethyl sulfonate weighed in a certain molar ratio to a three-necked flask equipped with a thermometer, nitrogen protection device and condenser, add concentrated sulfuric acid as a catalyst, and heat up to the specified time by magnetic stirring and then stop heating.

[0052] 2. After the reaction is complete, allow it to cool naturally, add sodium hydroxide, control the pH to be slightly alkaline, and separate and purify the crude product to finally obtain the desired dispersant component A.

[0053] 3. The final shield tunneling dispersant is obtained by compounding T50 and dispersant component A in a certain proportion, and the pH is controlled at a weakly acidic level.

[0054] Comparative Example 1

[0055] Raw material formula, by mass parts:

[0056]

[0057] Preparation steps:

[0058] 1. Add oxalic acid and sodium hydroxyethyl sulfonate weighed in a certain molar ratio to a three-necked flask equipped with a thermometer, nitrogen protection device and condenser, add concentrated sulfuric acid as a catalyst, and heat up to the specified time by magnetic stirring and then stop heating.

[0059] 2. After the reaction is complete, allow it to cool naturally, add sodium hydroxide, control the pH to be slightly alkaline, and separate and purify the crude product to finally obtain the desired dispersant component A.

[0060] 3. The final shield tunneling dispersant is obtained by compounding T50 and dispersant component A in a certain proportion, and the pH is controlled at a weakly acidic level.

[0061] Comparative Example 2

[0062] Raw material formula, by mass parts:

[0063]

[0064] Preparation steps:

[0065] 1. Add oxalic acid and sodium hydroxyethyl sulfonate weighed in a certain molar ratio to a three-necked flask equipped with a thermometer, nitrogen protection device and condenser, add concentrated sulfuric acid as a catalyst, and heat up to the specified time by magnetic stirring and then stop heating.

[0066] 2. After the reaction is complete, allow it to cool naturally, add sodium hydroxide, control the pH to be slightly alkaline, and separate and purify the crude product to finally obtain the desired dispersant component A.

[0067] 3. The final shield tunneling dispersant is obtained by compounding T50 and dispersant component A in a certain proportion, and the pH is controlled at a weakly acidic level.

[0068] Comparative Example 3

[0069] Only T50 was analyzed.

[0070] The above dispersant samples were subjected to performance testing, as detailed in the table below.

[0071]

[0072] Penetration force: Immerse a cotton disc in a dispersant solution of known concentration, and use a stopwatch to record the time required for the cotton disc to go from contacting the liquid surface to starting to settle. Take the average value of five measurements.

[0073] Kinematic viscosity: measured by a viscometer.

[0074] Metal corrosion resistance: In the laboratory at 25℃, 8cm standard iron nails are soaked in 50% diluted solution for 24 hours, dried, and then wiped with a cloth. The mass loss is calculated. If it does not exceed 1%, it is considered an excellent product; if it is greater than 1% but less than 1.5%, it is considered a qualified product.

[0075] Dispersion ability of cohesive soil: In the laboratory at 25℃, using a special dispersion ability testing device, a column of high-viscosity ceramic soil with a diameter of 1cm and a height of 4cm is placed into the device. The shield dispersant stock solution is prepared into a 10% diluted solution (by mass). If the high-viscosity ceramic soil column is completely dispersed in ≤30min, it is an excellent product; ≤40min is a good product; and ≤60min is a qualified product.

[0076] Foaming performance: In the laboratory at 25℃, the shield tunneling dispersant stock solution was prepared into a 2.5% diluted solution (mass ratio). 1000mL of this diluted solution was weighed into a 5000mL standard measuring cup and stirred continuously for 1 minute with a 50Hz mechanical stirrer. The foaming volume was recorded. A foaming volume ≥3500mL is considered an excellent product, a foaming volume ≥3000mL is considered a good product, and a foaming volume ≥2000mL is considered a qualified product.

[0077] The comparison of dispersant performance in the examples and comparative examples leads to the conclusion that the dispersant components A and T50 prepared by the esterification reaction of sodium hydroxyethyl sulfonate and oxalate have a synergistic effect, improving various properties of the dispersant. It has good dispersibility, permeability, and foaming properties, and low metal corrosivity. It can effectively improve problems such as mud cake formation on the cutterhead of the tunnel boring machine and improve construction efficiency.

[0078] The above performance comparison shows that the soil dispersant for shield tunneling provided by this invention has good permeability, low kinematic viscosity, low corrosivity to metal cutterheads, strong dispersibility in sticky soils, and excellent foaming performance.

[0079] To achieve stable dispersibility and uniform particle size, this invention, through experimental verification, fully considers factors such as chemical structure, hydrophilic-hydrophobic balance, molecular weight, and molecular weight distribution. These factors not only affect particle size and dispersion but also the dispersion stability of the target hydrophobic particles. The two-component dispersant of this invention consists of two parts: a nonpolar, negatively charged hydrophilic group and an oleophilic hydrocarbon chain. The hydrophobic portion (oleophilic hydrocarbon chain) of the dispersant is attracted to the surface of the hydrophobic particles, while the hydrophilic portion is solubilized by water. Both components contribute to dispersion, and their combined effect significantly enhances the dispersion. This dispersant can promote wettability modification, reduce interfacial tension and enhance electrostatic forces, improve steric hindrance, reduce apparent viscosity, and improve dispersibility.

[0080] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A soil dispersant for shield tunneling construction, characterized in that, Compound A and sodium sulfosuccinic acid dioctyl ester are compounded to form the soil dispersant, wherein the structural formula of the compound A is:

2. The soil dispersing agent for tunnel construction according to claim 1, wherein The compound A is prepared by esterification reaction of sodium hydroxyethyl sulfonate and oxalic acid.

3. The soil dispersing agent for tunnel construction according to claim 2, wherein The raw materials of the soil dispersant include, by mass fraction:

4. A method for producing the soil dispersant for a tunneling shield according to any one of claims 1 to 3, characterized by, The soil dispersant is prepared by the following steps: Step one: using oxalic acid and sodium hydroxyethyl sulfonate as raw materials, concentrated sulfuric acid as catalyst to prepare compound A; Step two: after the reaction in step one is completed, adjusting pH to weak alkaline, separating and purifying to obtain compound A; Step three: compounding compound A with sodium sulfosuccinic acid dioctyl ester to obtain the soil dispersant.

5. The method for producing a soil dispersant for a shield construction according to Claim 4, characterized by, In step two, sodium hydroxide is added to adjust pH to weak alkaline.

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