High-toughness and high-durability tmb wall back gravel grouting material and preparation method thereof

Abstract

The application relates to the technical field of building engineering, and more specifically to a high-toughness and high-durability TBM wall-back gravel grouting material and a preparation method thereof.A high-toughness and high-durability TBM wall-back gravel grouting material comprises the following raw materials in parts by weight: 800-1000 parts of fine sand, 30-50 parts of bentonite, 100-200 parts of fly ash, 400-600 parts of Portland cement, 70-100 parts of gypsum, 70-100 parts of modified rubber particles, 5-10 parts of an early strength agent and 400-600 parts of water; the modified rubber particles are grafted with hydroxyl groups and sulfur groups.The high-toughness and high-durability TBM wall-back gravel grouting material has excellent toughness and aging resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of building engineering, and more particularly to a high-toughness and high-durability TBM-wall-back gravel grouting material and a preparation method thereof. BACKGROUND

[0002] In recent years, the number of tunnels built by using the shield method in China gradually increases, many tunnel projects are distributed in high-intensity seismic areas, and shield tunnels are prone to be damaged to different degrees under strong earthquakes, but due to the complex location of the tunnels, the repair work of the tunnels is also difficult to carry out, therefore, in order to improve the safety of the tunnels under strong earthquakes, it is necessary to carry out the shock absorption technology research of the shield tunnels.

[0003] Synchronous grouting is a key link in the construction of shield tunnels, and the selection of the grouting material is also crucial, for this, the applicant considers that rubber particles are added in the grouting material, the toughness of the grouting material is improved through the buffering effect of the rubber particles, and thus an excellent shock absorption effect is obtained, however, due to the weak bonding of the interface transition zone between the rubber particles and the grouting material matrix, the toughness of the grouting material still needs to be improved. SUMMARY

[0004] In order to improve the interface between the rubber particles and the grouting material, so that the toughness of the grouting material is still insufficient, the application provides a high-toughness and high-durability TBM-wall-back gravel grouting material and a preparation method thereof.

[0005] In the first aspect, the application provides a high-toughness and high-durability TBM-wall-back gravel grouting material, which adopts the following technical scheme:

[0006] A high-toughness and high-durability TBM-wall-back gravel grouting material comprises the following raw materials by weight: 800-1000 parts of fine sand, 30-50 parts of bentonite, 100-200 parts of fly ash, 400-600 parts of Portland cement, 70-100 parts of gypsum, 70-100 parts of modified rubber particles, 5-10 parts of early strength agent and 400-600 parts of water; the modified rubber particles are grafted with hydroxyl groups and sulfur groups.

[0007] Preferably, the preparation method of the modified rubber particles is as follows:

[0008] Firstly, the rubber particles are soaked in 5% sodium hydroxide solution for 20-30 hours, then washed with water, and then added to 5% potassium permanganate solution, and the pH value of the solution is adjusted to 2-3 by sulfuric acid; then, the solution is heated to 50-70°C, and the oxidation reaction is stirred for 1-3 hours, during which the pH value is always controlled at 2-3 by 5% potassium permanganate solution and sulfuric acid, then washed with water, and finally soaked in sodium bisulfite solution for 1-2 hours at a soaking temperature of 50-70°C, and finally dried to obtain modified rubber particles.

[0009] In this application, the surface of the rubber particles is modified by oxidation agent sulfonation, which promotes the introduction of a large number of hydroxyl groups, carbon groups and sulfonic acid groups on the surface of the rubber particles. The introduction of these polar groups significantly improves the hydrophilicity of the rubber, improves the interface relationship between the rubber and the cement, and further promotes the adhesion strength between the rubber and the cement, thereby further improving the toughness of the TBM backfill gravel grouting material.

[0010] Preferably, the rubber particles include the following raw materials by weight: 90-110 parts of styrene-butadiene rubber, 4-6 parts of zinc oxide, 1-3 parts of stearic acid, 1-3 parts of sulfur, and 1-2 parts of an anti-aging accelerator, which is attapulgite loaded with 2-mercaptobenzimidazole derivatives, and contains selenium compounds and promoting groups in the anti-aging accelerator.

[0011] Although the addition of rubber particles can effectively improve the toughness of the TBM backfill gravel grouting material, due to the existence of factors such as tunnel vibration and climate, the TBM backfill gravel grouting material will continue to be subjected to thermal and oxidative aging, thereby causing the toughness of the TBM backfill gravel grouting material to decrease after long-term use.

[0012] 2-mercaptobenzimidazole derivatives can prevent the aging of rubber, and the mechanism is that 2-mercaptobenzimidazole derivatives can react with free radicals in rubber molecules, thereby neutralizing free radicals and stabilizing rubber molecules, preventing further oxidation and decomposition, and at the same time, 2-mercaptobenzimidazole derivatives can also maintain good anti-aging performance in high temperature and humid environment.

[0013] Selenium compounds can form stable chemical bonds with rubber molecules, thereby improving the intermolecular interaction between rubber and other components, and further improving the mechanical properties, anti-aging properties and electrical conductivity of rubber products. When used in combination with 2-mercaptobenzimidazole derivatives, the prepared rubber products will have more excellent anti-aging properties.

[0014] In addition, the introduction of hydroxyl and sulfur groups requires the oxidation of the surface of the rubber particles, and the presence of 2-mercaptobenzimidazole derivatives will limit the occurrence of oxidation, and the surface of the attapulgite contains a large number of pores, which can load 2-mercaptobenzimidazole derivatives, thereby playing a slow-release effect, reducing the influence of 2-mercaptobenzimidazole derivatives on the modification of rubber particles, and also playing an anti-aging role in the later use of the grouting material.

[0015] Preferably, the promoting group is a dithiocarbamic acid group.

[0016] Although selenium compounds can react with double bonds in rubber like sulfur compounds to form cross-linked structures, and even have more excellent aging resistance and stability, compared with sulfur compounds, the vulcanization speed of selenium compounds is slower, and the introduction of dithiocarbamic acid groups can exist as an auxiliary accelerator, thereby accelerating the progress of rubber vulcanization.

[0017] Specifically, the dithiocarbamic acid group molecule contains two interacting thioether bonds, and in the vulcanization process, the two thioether bonds are first broken, one sulfur atom reacts with a hydrogen atom in the rubber molecule to generate mercaptan, and the other sulfur atom reacts with a hydrogen atom in another rubber molecule to generate disulfide, and finally the mercaptan and disulfide react with hydrogen atoms to generate vulcanized rubber.

[0018] Preferably, the preparation method of the anti-aging accelerator is:

[0019] Dissolve 3-5 g of 2-mercaptobenzimidazole-selenium compound in 20-40 ml of anhydrous ethanol, then add 18-22 ml of an ethanol-water mixture containing 0.7-0.9 g of sodium hydroxide, the mass ratio of the two in the ethanol-water mixture is 1:1, stir at room temperature until clear, then cool the solution to 0°C, then add 5-6 ml of carbon disulfide-ethanol solution at a rate of 2 s / drop, the volume ratio of carbon disulfide to ethanol is 15:100, continue stirring for 20-40 min after the addition is completed, finally add 2-3 ml of 4-methylpiperidine, then stand for 5-10 min, then add 50 ml of iodine-potassium iodide aqueous solution at a rate of 1 s / drop, the concentration of iodine is 50.8 g / L, the concentration of potassium iodide is 50 g / L, after the addition is completed, add 4-8 g of attapulgite and continue stirring for 1-2 h, finally filter, wash, and dry by suction filtration to obtain the anti-aging accelerator.

[0020] Preferably, the preparation method of the 2-mercaptobenzimidazole-selenium compound is as follows: 2-4 g of 2-mercaptobenzimidazole is dissolved in 150-250 ml of anhydrous ethanol at room temperature, stirring continues until it is clear, then 15-25 ml of selenium dioxide-anhydrous ethanol solution is slowly added dropwise, the concentration of the selenium dioxide-anhydrous ethanol solution is 0.05 g / ml, the dropwise adding speed is 2 s / drop, the reaction temperature is controlled at 40-60 DEG C, after the dropwise adding is completed, stirring continues for 1-2 h, and finally filtration, washing, vacuum filtration and drying are performed to obtain the 2-mercaptobenzimidazole-selenium compound.

[0021] Preferably, the preparation method of the rubber particles is as follows:

[0022] The styrene-butadiene rubber is plasticized in an internal mixer, after being uniformly mixed, the styrene-butadiene rubber is transferred to a two-roll open mill for processing, zinc oxide, stearic acid, anti-aging accelerator and sulfur are added one by one during the processing, and after each addition, the mixture is uniformly mixed, and cutting, tumbling, extrusion and bubble removal are continuously performed during the mixing; after the mixing is completed, the styrene-butadiene rubber compound is placed in a dry environment for 20-30 h, and finally the rubber particles are obtained by cutting.

[0023] In a second aspect, the application provides a preparation method of a high-toughness and high-durability TBM back-wall gravel grouting material, which adopts the following technical scheme:

[0024] A preparation method of a high-toughness and high-durability TBM back-wall gravel grouting material is as follows:

[0025] Fine sand, bentonite, fly ash, Portland cement, gypsum, modified rubber particles, early strength agent and water are added to a mortar mixer, and stirring is performed for 2-5 min; then, the grouting pressure is set to 0.4-0.8 MPa, the flow rate is controlled at 50-120 L / min, four-point simultaneous grouting is adopted at the shield tail, the upper-to-lower ratio is 6.5:3.5, and the injection rate is 125-150%.

[0026] In summary, the application has the following beneficial effects:

[0027] 1. In the application, the surface of the rubber particles is modified by oxidation agent sulfonation, which promotes the introduction of a large number of hydroxyl groups, carbon groups and sulfonic acid groups on the surface of the rubber particles. The introduction of these polar groups significantly improves the hydrophilicity of the rubber, improves the interface relationship between the rubber and the cement, and further promotes the significant improvement of the bonding strength between the rubber and the cement, thereby further improving the toughness of the TBM back-wall gravel grouting material.

[0028] 2. Although the addition of rubber particles can effectively improve the toughness of the TBM back-wall gravel grouting material, due to the existence of factors such as tunnel vibration and climate, the TBM back-wall gravel grouting material will continue to be subjected to thermal and oxidative aging, thereby causing the toughness of the TBM back-wall gravel grouting material to decrease after long-term use;

[0029] 2-mercaptobenzimidazole derivatives can prevent the aging of rubber, the mechanism is that 2-mercaptobenzimidazole derivatives can react with free radicals in rubber molecules, thereby neutralizing free radicals and stabilizing rubber molecules, preventing further oxidation and decomposition, at the same time, 2-mercaptobenzimidazole derivatives can also maintain good anti-aging performance in high temperature and humid environment;

[0030] Selenium compounds can form stable chemical bonds with rubber molecules, thereby improving the intermolecular interaction between rubber and other components, and further improving the mechanical properties, aging resistance and electrical conductivity of rubber products. When used with 2-mercaptobenzimidazole derivatives, the prepared rubber products will have more excellent aging resistance.

[0031] The introduction of hydroxyl and sulfur groups requires oxidation treatment of the surface of rubber particles, and the presence of 2-mercaptobenzimidazole derivatives will limit oxidation. The surface of attapulgite contains a large number of pores, which can load 2-mercaptobenzimidazole derivatives, thereby achieving a slow-release effect, reducing the influence of 2-mercaptobenzimidazole derivatives during the modification of rubber particles, and also playing an anti-aging role during the later use of grouting materials.

[0032] 4、Although selenium compounds, like sulfur compounds, can react with double bonds in rubber to form cross-linked structures, and even have more excellent aging resistance and stability, compared with sulfur compounds, the vulcanization speed of selenium compounds is slower, and the introduction of dithiocarbamic acid groups can exist as an auxiliary accelerator, thereby accelerating the vulcanization process of rubber;

[0033] Specifically, the dithiocarbamic acid group molecule contains two interacting thioether bonds. During vulcanization, the two thioether bonds are first broken, one sulfur atom reacts with a hydrogen atom in a rubber molecule to form a mercaptan, and the other sulfur atom reacts with a hydrogen atom in another rubber molecule to form a disulfide. Finally, mercaptan and disulfide react with hydrogen atoms to form vulcanized rubber. DETAILED DESCRIPTION

[0034] The present application is further described in conjunction with Examples 1-6 and Comparative Example 1.

[0035] Fine sand CAS: 14808-60-7; bentonite CAS: 1302-78-9; fly ash Ⅱ; Portland cement CAS: 1327-39-5; gypsum CAS: 10101-41-4; early strength agent Xinzhuyuan Chemical Calcium formate; attapulgite CAS: 1337-76-4;

[0036] Potassium iodide, zinc oxide, stearic acid, and sulfur were purchased from Dongguan Fosite Rubber.

[0037] Styrene butadiene rubber SBR1502 Dongguan Siqi Rubber;

[0038] Sodium hydroxide, potassium permanganate, sulfuric acid, ethanol, caustic soda, iodine, potassium iodide, sodium bisulfite, 2-mercaptobenzimidazole, selenium dioxide, carbon disulfide were purchased from Shanghai Maikelin Biochemical Technology Co.

[0039] A high-toughness and high-durability TBM wall back gravel grouting material comprises the following raw materials by mass: 900 kg of fine sand, 40 kg of bentonite, 150 kg of fly ash, 500 kg of Portland cement, 90 kg of gypsum, 80 kg of modified rubber particles, 7 kg of early strength agent, and 500 kg of water.

[0040] The preparation method of the high-toughness and high-durability TBM wall back gravel grouting material is as follows: the fine sand, bentonite, fly ash, Portland cement, gypsum, modified rubber particles, early strength agent, and water are added to a mortar mixer, and the stirring time is 4 min; then the grouting pressure is set to 0.6 MPa, the flow rate is controlled at 100 L / min, the shield tail four-point simultaneous grouting is adopted, the upper and lower part ratio is 6.5:3.5, and the injection rate is 125-150%.

[0041] The modified rubber particles are grafted with hydroxyl and sulfur groups, and the preparation method of the modified rubber particles is as follows:

[0042] First, the rubber particles are soaked in a 5% sodium hydroxide solution for 24 h, then washed with water, then added to a 5% potassium permanganate solution, and the pH value of the solution is adjusted to 3 by sulfuric acid; then, the solution is heated to 60℃, and the oxidation reaction is stirred for 2 h, during which the pH value is controlled at 3 by 5% potassium permanganate solution and sulfuric acid, then washed with water, and finally soaked in a sodium bisulfite solution for 2 h at a soaking temperature of 60℃, and finally dried to obtain the modified rubber particles.

[0043] The rubber particles comprise the following raw materials by mass: 100 g of styrene butadiene rubber, 5 g of zinc oxide, 2 g of stearic acid, and 2 g of sulfur.

[0044] The preparation method of the rubber particles is as follows: the styrene butadiene rubber is plasticized in an internal mixer, and after mixing uniformly, the styrene butadiene rubber is transferred to a two-roll open mill for processing, and the zinc oxide, stearic acid, and sulfur are added one by one during the processing, and after each addition, the mixture is mixed uniformly, and cutting, tumbling, extrusion, and bubble removal are continuously performed during the mixing process; after the mixing is completed, the styrene butadiene rubber compound is left to stand in a dry environment for 24 h, and finally the rubber particles are obtained by cutting.

[0045] The difference from Example 1 is that the rubber particles comprise the following raw materials by mass: 100 g of styrene butadiene rubber, 5 g of zinc oxide, 2 g of stearic acid, 2 g of sulfur, and 1.5 g of anti-aging accelerator.

[0046] The preparation method of the rubber particles is as follows: plasticizing the styrene-butadiene rubber in an internal mixer, transferring the styrene-butadiene rubber to a two-roll open mill after uniform mixing, adding zinc oxide, stearic acid, sulfur and an anti-aging accelerator one by one during the processing, and fully mixing after each addition, continuously cutting, tumbling, extruding and bubble removal during the mixing process; after the mixing is completed, the styrene-butadiene rubber compound is left to stand in a dry environment for 24 h, and finally the rubber particles are obtained by cutting.

[0047] The anti-aging accelerator contains a 2-mercaptobenzimidazole derivative and a selenide, and the preparation method of the anti-aging accelerator is as follows:

[0048] At room temperature, 3 g of 2-mercaptobenzimidazole is dissolved in 200 ml of anhydrous ethanol, continuously stirred until clear, and then 20 ml of a selenium dioxide-anhydrous ethanol solution is slowly added dropwise, the concentration of the selenium dioxide-anhydrous ethanol solution is 0.05 g / ml, the dropwise addition speed is 2 s / drop, the reaction temperature is controlled at 50°C, after the dropwise addition is completed, continuous stirring is carried out for 2 h, and finally filtration, washing and vacuum filtration drying are carried out to obtain the anti-aging accelerator.

[0049] The difference from Example 2 is that the anti-aging accelerator is attapulgite loaded with a 2-mercaptobenzimidazole derivative, and the anti-aging accelerator contains a selenide.

[0050] The preparation method of the anti-aging accelerator is as follows:

[0051] At room temperature, 3 g of 2-mercaptobenzimidazole is dissolved in 200 ml of anhydrous ethanol, continuously stirred until clear, and then 20 ml of a selenium dioxide-anhydrous ethanol solution is slowly added dropwise, the concentration of the selenium dioxide-anhydrous ethanol solution is 0.05 g / ml, the dropwise addition speed is 2 s / drop, the reaction temperature is controlled at 50°C, after the dropwise addition is completed, 6 g of attapulgite is added, continuous stirring is carried out for 2 h, and finally filtration, washing and vacuum filtration drying are carried out to obtain the anti-aging accelerator.

[0052] The difference from Example 3 is that the anti-aging accelerator also contains a dithiocarbamic acid group.

[0053] The preparation method of the anti-aging accelerator is as follows:

[0054] Dissolve 4 g of 2-mercapto benzimidazole-selenide in 30 ml of anhydrous ethanol, then add 120 ml of an ethanol-water mixture containing 0.8 g of sodium hydroxide, the mass ratio of the two in the ethanol-water mixture is 1:1, stir at room temperature until clear, then cool the solution to 0°C, then add 6 ml of carbon disulfide-ethanol solution at a rate of 2 s / drop, the volume ratio of carbon disulfide to ethanol is 15:100, continue stirring for 30 min after the addition is complete, finally add 3 ml of 4-methylpiperidine, then stand for 8 min, then add 50 ml of an aqueous solution of iodine-potassium iodide at a rate of 1 s / drop, the concentration of iodine is 50.8 g / L, the concentration of potassium iodide is 50 g / L, after the addition is complete, add 6 g of attapulgite and continue stirring for 2 h, finally filter, wash, vacuum filter and dry to obtain the anti-aging accelerator.

[0055] The preparation method of 2-mercapto benzimidazole-selenide is as follows:

[0056] Dissolve 3 g of 2-mercapto benzimidazole in 200 ml of anhydrous ethanol at room temperature, continue stirring until clear, then slowly add 20 ml of selenium dioxide-anhydrous ethanol solution at a rate of 2 s / drop, the concentration of the selenium dioxide-anhydrous ethanol solution is 0.05 g / ml, control the reaction temperature at 50°C, continue stirring for 2 h after the addition is complete, finally filter, wash, vacuum filter and dry to obtain 2-mercapto benzimidazole-selenide.

[0057] The difference between Example 4 and the present example is that the addition amounts of the components of the high-toughness and high-durability TBM wall post-gravel grouting material are different, as shown in Table 1.

[0058] Table 1: Addition amounts of components of high-toughness and high-durability TBM wall post-gravel grouting material in Example 4-Example 6

[0059]

[0060] The difference between Example 1 and the present example is that the surface of the rubber particles is no longer modified, i.e., there are no hydroxyl groups and sulfur groups on the surface of the rubber particles.

[0061] I. Compressive strength test

[0062] Take three samples from each of Example 1-Example 6 and Comparative Example 1, then test the compressive strength of the above samples according to GB / T50123-2019 “Geotechnical Test Code”, obtain the 7-day compressive strength and take the average value.

[0063] II. Anti-aging performance test

[0064] Three samples were taken from each of the examples 1-6 and the comparative example 1, and then placed in a M115 thermal oxidation aging oven with an aging temperature of 100 DEG C and an aging time of 24 hours. Then, the compressive strength of the samples after aging was tested again according to GB / T50123-2019 “Geotechnical Test Code”. Finally, the compressive strength change amount was calculated.

[0065] The compressive strength change amount = (7-day compressive strength - 7-day compressive strength after aging) / 7-day compressive strength x 100%.

[0066] The test data is shown in Table 2.

[0067] Table 2 Test data table of examples 1-6 and the comparative example 1

[0068]

[0069] According to the examples 1 and the comparative example 1 and in combination with Table 2, it can be seen that the 7-day compressive strength of the example 1 is significantly improved, but the compressive strength change amount is also significantly improved, which shows that the introduction of hydroxyl and sulfur groups can effectively improve the toughness of the TBM backfill gravel grouting material, but also affects the aging resistance of the TBM backfill gravel grouting material.

[0070] The reason is that in the present application, the surface of the rubber particles is modified by oxidation and sulfonation, which promotes the introduction of a large number of hydroxyl, carbon and sulfonic groups on the surface of the rubber particles. The introduction of these polar groups significantly improves the hydrophilicity of the rubber, improves the interface relationship between the rubber and the cement, and further promotes the bonding strength between the rubber and the cement, thereby further improving the toughness of the TBM backfill gravel grouting material.

[0071] At the same time, the method of oxidation modification also changes the internal structure of the rubber particles in the TBM backfill gravel grouting material, thereby accelerating the aging of the rubber particles, and further affecting the durability of the TBM backfill gravel grouting material.

[0072] According to the examples 1 and 2 and in combination with Table 2, it can be seen that the 7-day compressive strength of the example 2 is significantly improved compared with the example 1, and at the same time, the compressive strength change amount of the example 2 is also significantly reduced, which shows that the use of the aging resistance promoter can improve the durability of the TBM backfill gravel grouting material while effectively improving the toughness of the TBM backfill gravel grouting material.

[0073] The reason is that the 2-mercapto benzimidazole derivative can prevent the aging of rubber, and the mechanism is that the 2-mercapto benzimidazole derivative can react with free radicals in the rubber molecule, thereby neutralizing the free radicals and stabilizing the rubber molecule, preventing further oxidation and decomposition, and at the same time, the 2-mercapto benzimidazole derivative can also maintain good anti-aging performance in high temperature and humid environment.

[0074] Selenium can form a stable chemical bond with rubber molecules, thereby improving the intermolecular interaction between rubber and other components, and further improving the mechanical properties, aging resistance and electrical conductivity of the rubber product, and after being used with the 2-mercapto benzimidazole derivative, the prepared rubber product will have more excellent aging resistance.

[0075] As can be seen from Examples 2 and 3 and in combination with Table 2, although the 7-day compressive strength of Example 3 has no change, the compressive strength change amount of Example 3 is significantly reduced, which shows that the addition of palygorskite can effectively improve the durability of the TBM backfill gravel injection material.

[0076] The reason may be that the introduction of hydroxyl and sulfur groups requires oxidation treatment of the surface of the rubber particles, and the presence of 2-mercapto benzimidazole derivative will limit the oxidation, and the surface of palygorskite contains a large number of pores, which can load 2-mercapto benzimidazole derivative, thereby playing a slow-release effect, reducing the influence of 2-mercapto benzimidazole derivative on the modification of rubber particles, and also playing an anti-aging role in the later use of the injection material.

[0077] As can be seen from Examples 3 and 4 and in combination with Table 2, compared with Example 3, the 7-day compressive strength of Example 4 is obviously improved, but the compressive strength change amount of Example 4 is basically unchanged, which shows that the introduction of dithio carbamate group can further improve the toughness of the TBM backfill gravel injection material.

[0078] The reason is that although selenium, like sulfur, can react with double bonds in rubber to form a cross-linked structure, and even has more excellent aging resistance and stability, compared with sulfur, the vulcanization speed of selenium is slower, and the introduction of dithio carbamate group can exist as an auxiliary accelerator, thereby accelerating the vulcanization process of rubber, thereby improving the mechanical strength and stability of the rubber particles.

[0079] Specifically, the dithio carbamic acid group contains two interaction thioether bonds in the molecule, in the vulcanization process, the two thioether bonds are first broken, one of the sulfur atoms reacts with the hydrogen atoms in the rubber molecules to generate mercaptan, the other sulfur atom reacts with the hydrogen atoms in another rubber molecule to generate disulfide, and finally the mercaptan and disulfide react with the hydrogen atoms to generate vulcanized rubber.

[0080] It can be seen from the embodiments 4-6 and in combination with Table 2 that the 7-day compressive strength or the compressive strength change amount of the embodiments 5-6 is obviously deteriorated compared with the embodiment 4, thus indicating that when the components of the TBM backfill gravel grouting material are prepared by using the adding amount of the embodiment 4, the TBM backfill gravel grouting material prepared has better toughness and durability.

[0081] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A high-toughness, high-durability TBM wall backfill grouting material, characterized in that, The raw materials include the following parts by weight: 800-1000 parts fine sand, 30-50 parts bentonite, 100-200 parts fly ash, 400-600 parts silicate cement, 70-100 parts gypsum, 70-100 parts modified rubber granules, 5-10 parts early strength agent, and 400-600 parts water; the modified rubber granules are grafted with hydroxyl and sulfonyl groups; The rubber granules comprise the following raw materials in parts by weight: 90-110 parts styrene-butadiene rubber, 4-6 parts zinc oxide, 1-3 parts stearic acid, 1-3 parts sulfur and 1-2 parts aging accelerator, wherein the aging accelerator is attapulgite loaded with 2-mercaptobenzimidazole derivative, and the aging accelerator contains selenide and accelerating groups. The promoting group is a dithiocarbamate group.

2. The high-toughness, high-durability TBM wall backfill grouting material according to claim 1, characterized in that, The method for preparing the modified rubber particles is as follows: First, the rubber granules are soaked in a 5% sodium hydroxide solution for 20-30 hours, then washed with water. Next, a 5% potassium permanganate solution is added, and the pH of the solution is adjusted to 2-3 with sulfuric acid. Then, the solution is heated to 50-70℃ and stirred for 1-3 hours for oxidation reaction. During this period, the pH is maintained at 2-3 with the 5% potassium permanganate solution and sulfuric acid. After washing with water, the rubber granules are soaked in a sodium bisulfite solution for 1-2 hours at a soaking temperature of 50-70℃. Finally, they are dried to obtain modified rubber granules.

3. The high-toughness, high-durability TBM wall backfill grouting material according to claim 1, characterized in that, The method for preparing the anti-aging accelerator is as follows: Dissolve 3-5g of 2-mercaptobenzimidazole-selenide in 20-40ml of anhydrous ethanol, then add 18-22ml of an ethanol-water mixture containing 0.7-0.9g of caustic soda (mass ratio of ethanol to water: 1:1). Stir at room temperature until clear, then cool the solution to 0℃. Next, add 5-6ml of carbon disulfide-ethanol solution at a rate of 2s / drop (volume ratio of carbon disulfide to ethanol: 15:100). After the addition is complete, continue stirring for 20-40min. Finally, add 2-3ml of 4-methylpiperidine and let stand for 5-10min. Then, add 50ml of iodine-potassium iodide aqueous solution at a rate of 1s / drop (iodine concentration: 50.8g / L, potassium iodide concentration: 50g / L). After the addition is complete, add 4-8g of attapulgite and continue stirring for 1-2h. Finally, filter, wash, and dry to obtain the anti-aging accelerator.

4. The high-toughness, high-durability TBM wall backfill grouting material according to claim 3, characterized in that, The preparation method of the 2-mercaptobenzimidazole-selenide is as follows: at room temperature, 2-4 g of 2-mercaptobenzimidazole is dissolved in 150-250 ml of anhydrous ethanol and stirred continuously until clear. Then, 15-25 ml of selenium dioxide-anhydrous ethanol solution with a concentration of 0.05 g / ml and a dropping rate of 2 s / drop are slowly added dropwise. The reaction temperature is controlled at 40-60℃. After the addition is completed, the mixture is stirred continuously for 1-2 h. Finally, the mixture is filtered, washed, and dried to obtain 2-mercaptobenzimidazole-selenide.

5. The high-toughness, high-durability TBM wall backfill grouting material according to claim 1, characterized in that, The method for preparing the rubber granules is as follows: Styrene-butadiene rubber (SBR) is plasticized in an internal mixer and then transferred to a two-roll mill for processing. During the processing, zinc oxide, stearic acid, aging accelerator, and sulfur are added one by one, and the mixture is thoroughly mixed after each addition. During the mixing process, cutting, tumbling, extrusion, and defoaming are continuously carried out. After the mixing is completed, the SBR compound is allowed to stand in a dry environment for 20-30 hours, and finally granulated to obtain rubber granules.

6. A method for preparing a high-toughness, high-durability TBM wall backfill grouting material according to any one of claims 1-5, characterized in that, Its preparation method is as follows: Add fine sand, bentonite, fly ash, silicate cement, gypsum, modified rubber granules, early strength agent and water to the mortar mixer and mix for 2-5 minutes. Then set the grouting pressure to 0.4-0.8 MPa, control the flow rate at 50-120 L / min, and use four points of simultaneous grouting at the shield tail, with an upper and lower part ratio of 6.5:3.5 and an injection rate of 125-150%.

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