Composite grouting material for water-rich fault fracture zone as well as preparation method and application of composite grouting material

Abstract

The invention relates to the technical field of grouting reinforcement materials, in particular to a composite grouting material for a water-rich fault fracture zone and a preparation method and application of the composite grouting material. The composite grouting material comprises water, compound cement, slag, an exciting agent, a water-resistant dispersing agent, a water reducing agent and a defoaming agent, the water-cement ratio of the water to the compound cement is (0.8-1.2): 1; the compound cement is obtained by compounding Portland cement and sulphoaluminate cement according to a mass ratio of (3-2): 1. The reasonable proportion is designed according to the water-rich degree of the fault fracture zone and the strength of the surrounding rock, solid waste resource utilization is achieved by doping the superfine slag powder with the increased proportion, the property of the grout is adjusted so as to achieve the water dispersibility resistance of grouting and the strength of a reinforcing body, and the stratum stability is improved.

Description

Technical Field

[0001] This invention relates to the field of grouting reinforcement materials, specifically to a composite grouting material for water-rich fault fracture zones, its preparation method, and its application. Background Technology

[0002] In construction engineering, especially in tunnel engineering, water-rich fault fracture zones are a common adverse geological phenomenon. They are characterized by fractured and low-strength rock masses leading to poor surrounding rock stability, frequent groundwater activity, and seismic sensitivity, which can pose significant safety hazards to the construction and subsequent maintenance of engineering projects.

[0003] To ensure the construction safety and performance of engineering structures meet design standards, grouting materials are needed to reinforce water-rich fault fracture zones. This involves effectively filling the fissures and pores in the strata with grout, which then solidifies into a unified whole, thereby improving the stability of the surrounding rock. Based on the characteristics of water-rich fault fracture zones, grouting materials need good water erosion resistance, suitable setting time, and high strength of the solidified rock to ensure effective reinforcement. However, existing grouting materials, such as ordinary cement, have poor water erosion resistance. To improve this resistance, cement-water glass composites are commonly used; however, the solidified body with added water glass has poor durability, seriously affecting safety during construction. Furthermore, grouting requires the use of more expensive dual-liquid grouting pumps, making the process complex, and other related grouting properties often fail to meet the performance requirements for effective reinforcement of water-rich fault fracture zones. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a composite grouting material for water-rich fault fracture zones, its preparation method, and its application. This solves the technical problems of poor water erosion resistance and poor durability of existing grouting materials and cement-water glass double-slurry solidified bodies. Furthermore, the grouting material of this invention also achieves solid waste resource utilization and reduces carbon emissions by incorporating slag powder.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a composite grouting material for water-rich fault fracture zones, comprising water, compound cement, slag, activator, anti-water dispersant, water-reducing agent, and defoamer; The water-cement ratio of the water to the composite grouting material is 0.8~1.2∶1; The amount of slag added accounts for 40% to 70% of the mass of the compound cement; The amount of the activator added is 4% to 6% of the mass of the compound cement; The amount of the anti-water dispersant agent added accounts for 0.6% to 0.8% of the mass of the compound cement; The water-reducing agent is added at a rate of 0.3% to 0.5% of the mass of the compound cement. The amount of defoamer added is 1% to 1.4% of the mass of the compound cement; The compound cement is obtained by mixing silicate cement and sulfoaluminate cement in a mass ratio of 3 to 2:1.

[0006] The composite grouting material of this invention does not contain water glass. By compounding cement and solid waste slag, and with the assistance of other reagents, the composite grouting material exhibits excellent resistance to water dispersibility and solidification strength, improving formation stability and ensuring construction safety. Compared to existing technologies using silicate cement, this invention adds sulfoaluminate cement, whose main mineral components are anhydrous calcium sulfoaluminate and dicalcium silicate. During hydration, anhydrous calcium sulfoaluminate reacts rapidly with gypsum to generate ettringite and aluminum hydroxide gel. These products can form a needle-like crystal framework structure within hours, providing early mechanical support; the aluminum hydroxide gel fills the pores, jointly enhancing early strength. Thus, tunnel excavation can be carried out immediately after grouting, improving construction efficiency. By adding slag, a solid waste material whose main mineral components are calcium oxide, silicon dioxide, and aluminum oxide, the aqueous solution becomes strongly alkaline and provides silicon ions under the action of an activator. This causes the active silicon dioxide and aluminum oxide in the slag to dissolve into silicate and aluminate ions. Calcium ions combine with silicate ions to form calcium-silicon-hydrate gel (CSH), which constitutes the main strength framework of the material. Aluminate ions combine with calcium and silicate ions to form aluminum-containing calcium aluminosilicate hydrate (CASH) gel, which fills the pores and improves the density. This process enables the resource utilization of slag solid waste and reduces carbon emissions.

[0007] In a preferred embodiment of the present invention, the anti-water dispersant is methyl hydroxyethyl cellulose, which has good compatibility with other external admixtures. Its polymer network structure can trap the gel formed by cement and slag powder, forming a stable spatial structure, thereby improving the compaction rate and strength of the grout.

[0008] In a preferred embodiment of this invention, the defoamer is a polyether-modified organosilicon liquid defoamer with a pH value of 6-8. It is a polyether-siloxane copolymer obtained by introducing polyether segments into siloxane molecules. Through the synergistic effect of hydrophobic and hydrophilic dual segments, it interferes with the elasticity of the liquid film, causing bubbles to lose their self-repairing ability and collapse. Furthermore, the dense molecular film formed on the slurry surface by the co-construction of polyether and organosilicon can hinder gas diffusion into the liquid film, preventing the formation of new bubbles. This defoamer has the characteristics of rapid defoaming, long foam suppression time, low dosage, low cost, and wide application range.

[0009] In a preferred embodiment of the present invention, the slag is S95 mineral powder.

[0010] In a preferred embodiment of the present invention, the activator is composed of calcium hydroxide and calcium silicate in a mass ratio of 1 to 1.2:1.

[0011] In a preferred embodiment of the present invention, the water-reducing agent is a polycarboxylate water-reducing agent.

[0012] In a preferred embodiment of the present invention, the composite grouting material further includes an early-strength agent, which accounts for 0.5% to 4% of the mass of the compound cement. Since the surrounding rock strength in water-rich fault fracture zones is relatively low, adding an early-strength agent can significantly improve the early strength of the reinforced solid after grouting, thereby enhancing the stability of the reinforced surrounding rock.

[0013] In a preferred embodiment of the present invention, the early-strength agent is obtained by compounding triethanolamine, aluminum sulfate, and calcium nitrite in a mass ratio of 0.02~0.04:1.2~1.5:1. The early-strength agent obtained by compounding the three components is superior to the early-strength agent of a single component.

[0014] This invention provides a method for preparing the above-mentioned composite grouting material, comprising the following steps: Weigh each raw material according to its mass percentage; After adding water-reducing agent and alkali activator to water and stirring, then adding compound cement and slag and stirring, then adding defoamer and anti-water dispersing agent and stirring, a composite grouting material is obtained. Alternatively, water-reducing agent and alkali activator can be added to water and stirred, then compound cement and slag can be added and stirred, followed by defoamer, anti-water dispersing agent and early strength agent, and stirred to obtain composite grouting material.

[0015] This invention provides an application of the above-mentioned composite grouting material as a grouting agent in the reinforcement treatment of water-rich fault fracture zones. The composite grouting material is injected into the formation through a single-liquid grouting pump at a grouting pressure of 1.2 to 1.3 times the pore water pressure.

[0016] Compared with the prior art, the present invention has the following beneficial effects.

[0017] This invention utilizes a composite cement made by blending silicate cement and sulfoaluminate cement at a mass ratio of 3-2:1. This effectively improves the slurry's water separation rate, shortens initial and final setting times, and reduces slurry shrinkage. Compared to using silicate cement alone, sulfoaluminate cement, during hydration, rapidly reacts its anhydrous calcium sulfoaluminate with gypsum to form ettringite and aluminum hydroxide gel, providing early mechanical support and early strength. By adding slag, a solid waste material, the active silica and aluminum oxide in the slag dissolve into silicate and aluminate ions under the action of an activator. Calcium ions combine with silicate ions to form calcium-silica-hydrate gel, which fills the pores, thereby improving density and effectively enhancing the utilization of slag. By mixing water and compound cement at a water-cement ratio of 0.8 to 1.2:1, the setting time can be shortened and the strength of the aggregate can be controlled. Furthermore, by controlling the amount of other reagents, the resulting composite grouting material has excellent mechanical properties and resistance to water dispersion. It also has advantages such as good fluidity, controllable grouting time, low water separation rate, and reasonable consistency. The solidified body obtained after grouting has significant early strength characteristics and high strength, which effectively improves the stability of the formation. Excavation can be carried out immediately after grouting, improving construction efficiency and ensuring the safety of engineering construction. Attached Figure Description

[0018] Figure 1 The following are graphs showing the effects of different component addition amounts on the setting time of composite grouting materials: (a) shows the effect of water-cement ratio on setting time; (b) shows the effect of mineral powder content on setting time; (c) shows the effect of alkali activator content on setting time; (d) shows the effect of cellulose content on setting time; (e) shows the effect of water-reducing agent content on setting time; and (f) shows the effect of defoamer content on setting time.

[0019] Figure 2 The following are graphs showing the effects of different component addition amounts on the fluidity of composite grouting materials: (a) shows the effect of water-cement ratio on fluidity, (b) shows the effect of mineral powder content on fluidity, (c) shows the effect of alkali activator content on fluidity, (d) shows the effect of cellulose content on fluidity, (e) shows the effect of water-reducing agent content on fluidity, and (f) shows the effect of defoamer content on fluidity.

[0020] Figure 3 Figures showing the effects of different component addition amounts on the water scour resistance of composite grouting materials are provided. Among them, (a) is the water-cement ratio, (b) is the mineral powder content, (c) is the alkali activator content, (d) is the cellulose content, (e) is the water-reducing agent content, and (f) is the defoamer content.

[0021] Figure 4 The following diagrams illustrate the effects of different component addition amounts on the strength of the composite grouting material: (a) shows the effect of water-cement ratio on the strength of the grout, (b) shows the effect of mineral powder content on the strength of the grout, (c) shows the effect of alkali activator content on the strength of the grout, (d) shows the effect of cellulose content on the strength of the grout, (e) shows the effect of water-reducing agent content on the strength of the grout, and (f) shows the effect of defoamer content on the strength of the grout.

[0022] Figure 5 The figure shows the effect of early strength agent on the gelation time of slurry.

[0023] Figure 6 The figure shows the effect of early strength agent on the compressive strength of the consolidated body.

[0024] Figure 7 Images of fractured rock mass are shown, where (a) is an image of the grouting and solidification of the fractured rock mass, and (b) is an image of the core sample taken out. The sample refers to the prepared core sample, and the original core sample refers to the core sample taken out after drilling.

[0025] Figure 8 The diagram shows the characteristic changes in seepage pressure of the composite grouting material at different measuring points; among them, (a) is the stress-strain curve of the solid under 0.3MPa water pressure, (b) is the stress-strain curve of the solid under 0.2MPa water pressure, and (c) is the stress-strain curve of the solid under 0MPa water pressure.

[0026] Figure 9 This is a curve showing the stress variation of the shear strength of the composite grouting material.

[0027] Figure 10 This is a graph showing the characteristic changes in seepage pressure at different measuring points.

[0028] Figure 11 The figures show the final pore pressure values ​​at the end of grouting under different water pressure conditions; (a) shows the final pore pressure values ​​at the end of grouting under a water pressure of 0.2 MPa; (b) shows the final pore pressure values ​​at the end of grouting under a water pressure of 0.3 MPa; in the figures, C1~C8 represent measuring points.

[0029] Figure 12 This is a graph showing the final values ​​of seepage pressure at measuring points under different water pressure conditions.

[0030] Figure 13 The images show CT scan slices of composite grouting material samples; (a) is CT scan slice 1, (b) is CT scan slice 2, and (c) is CT scan slice 3. In the images, 1 represents the bottom of the sample, 2 represents the lower middle part of the sample, 3 represents the upper middle part of the sample, and 4 represents the top of the sample.

[0031] Figure 14 The images are CT scan reconstructions of composite grouting material samples; (a) is the top reconstruction, (b) is the side reconstruction, and (c) is the bottom reconstruction.

[0032] Figure 15 The effect of modeling a numerical model.

[0033] Figure 16 This is a schematic diagram of the grouting simulation state.

[0034] Figure 17 The figure shows the grout diffusion length during the grouting process and the numerical simulation results. Detailed Implementation

[0035] To address the aforementioned technical problems, this invention provides a composite grouting material, its preparation method, and its application. The technical solution and embodiments of this invention will now be described in detail with reference to the accompanying drawings.

[0036] The present invention will now be described in detail through specific embodiments. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] The raw materials and components used in the following embodiments are as follows.

[0038] In the following examples, the English translation is as follows: Methyl hydroxyethyl cellulose is referred to as HEMC.

[0039] The polycarboxylate superplasticizer, a high-efficiency polycarboxylate superplasticizer, was purchased from Shandong Yousuo Chemical Technology Co., Ltd., designated as PC. The fatty alcohol defoamer was purchased from Guangdong Tianfeng Defoamer Co., Ltd., model DP-622, hereinafter referred to as DP-622. The polyether-modified silicone defoamer was purchased from Guangdong Tianfeng Defoamer Co., Ltd., model PDA, hereinafter referred to as PDA. The methyl hydroxyethyl cellulose was purchased from Hebei Renqiu Pengyu Chemical Co., Ltd., with a viscosity of 5W.

[0040] 1. Determination of compound cement.

[0041] Cement has advantages such as high strength, good durability, non-toxicity, ease of use, and reasonable price. Blending sulfoaluminate cement and silicate cement can improve the grout's water separation rate, shorten initial and final setting times, and reduce grout shrinkage. Therefore, blended cement materials were used as the grout base material in the experiment. The cement used in the experiment was all from Shandong Zhucheng Jiuqi Building Materials Co., Ltd., including silicate cement and sulfoaluminate cement, mixed in a 3:1 mass ratio. Its chemical composition, mineral composition, and basic physical properties are shown in Tables 1 and 2 below.

[0042] Table 1. Mineral composition and chemical composition of cement Note: P·O42.5 indicates silicate cement, R·SAC42.5 indicates sulfoaluminate cement, and - indicates that it does not contain this item. The same applies below.

[0043] Table 2 Basic Physical Properties of Cement 2. Determination of slag.

[0044] The slag in this embodiment is slag powder, a fine powder material processed from industrial by-products. It can be used as a new type of admixture for high-performance concrete, thereby achieving the purpose of solid waste utilization. The slag used in this embodiment comes from Henan Wodemei Environmental Protection Technology Co., Ltd. The slag powder S95 was selected and tested by Henan Risheng Comprehensive Testing Co., Ltd. to obtain its basic physical properties and mass fractions, as shown in Tables 3 and 4 below.

[0045] Table 3. Mass fractions of slag powder Table 4 Basic physical properties of slag powder The S95 slag powder used in this invention meets the relevant index requirements specified in GB / T18046-2017 "Granulated blast furnace slag powder for use in cement, mortar and concrete".

[0046] 3. Determination of other reagents.

[0047] Anti-water dispersants are mainly classified into two categories: inorganic and organic. Inorganic dispersants can improve the anti-water dispersibility of slurry by increasing its viscosity and cohesion. Organic dispersants are divided into synthetic and natural types. Natural dispersants mainly include starch, sugars, and plant gum derivatives, while synthetic dispersants mainly include polyacrylamide and cellulose. Among them, the synthetic organic polymeric anti-water dispersant methyl hydroxyethyl cellulose is a non-ionic cellulose ether that is soluble in water and has water-retaining and thickening effects in cement slurry. This type of cellulose also has good compatibility with other admixtures. In this embodiment of the invention, HEMC is used as an anti-water dispersant to regulate the slurry's dispersibility. To improve the slurry's injectability, a high-efficiency water-reducing agent is used to optimize its flowability. The water-reducing agent used is polycarboxylate high-efficiency water-reducing agent, which has good applicability to mixed mortar, improves slurry flowability, and enhances the early and late strength of the slurry. The technical performance indicators of polycarboxylate high-efficiency water-reducing agent are shown in Table 5.

[0048] Table 5 PC Technical Performance Indicators Defoamers DP-621, DP-622, and PDA were used to compare their defoaming performance, aggregate strength, and flowability of cement slurry. In the defoamer selection test, the water-cement ratio of the water to the compound cement was 0.8. Based on the mass of the compound cement as 100%, the following components were used: 40% slag powder, 0.4% 5W cellulose ether, 0.3% water-reducing agent, 4% activator, and 1% defoamer. The defoamers used were DP-621, DP-622, and PDA. The defoaming performance, aggregate strength, and flowability of these three defoamers were tested and discussed. The results of the tests yielded the characteristics of the three slurries, and the effects of the three defoamers on the slurry are shown in Table 6. The defoaming performance in the table is based on specimens with intermediate splitting after stone formation. The number of larger pores per unit area is calculated to be ≥0.8m. The fluidity is measured by a slurry flowability tester to determine the slurry spread. The slurry stone strength is compared by measuring the compressive strength of the specimens under standard curing conditions (temperature 20℃±2℃, humidity above 90%, curing for 3 days) using a pressure testing machine with a range of 80kN.

[0049] Table 6. Statistics on the properties of slurry Note: / indicates that the item is not included.

[0050] Table 6 shows that the addition of the three defoamers to the slurry can absolutely change the slurry properties. All three defoamers in Table 6 have good compatibility with the anti-dispersion slurry. After adding the defoamers, the slurry fluidity is improved to a certain extent without reducing the fluidity loss over time. Specifically, the DP-622 slurry showed a 6.58% increase in 3-day stone compressive strength compared to the control group, while the PDA slurry had the highest fluidity at 21.6 cm, an increase of 29.34%. The defoaming performance of all three slurries was greater than the control group, with PDA > DP-621 > DP-622. Through comparison, the PDA polyether modified silicone defoamer has the advantages of more significant defoaming effect, higher stone strength, and better fluidity. The following examples use the PDA polyether modified silicone defoamer as the chemical defoaming agent for the anti-dispersion slurry.

[0051] The following is a detailed description of a composite grouting material for water-rich fault fracture zones, its preparation method, and its application.

[0052] The experiment used silicate cement, sulfoaluminate cement and slag powder as the main materials. By studying the influence of the relevant proportions of admixtures on the material properties, a better grouting slurry, namely composite grouting material, was obtained. The composite grouting material has good mechanical properties and water dispersibility, as well as good fluidity, controllable grouting time, low water separation rate and reasonable consistency. The specific process is as follows.

[0053] 1. Determine the composition of each component through experiments.

[0054] 1.1 Experimental Design: Orthogonal experiments were conducted to study the gelation time, fluidity, water separation rate, water scourability, and aggregate strength of the grout under multiple factor combinations. The focus was on the water scourability, fluidity, and mechanical strength of the aggregate, thereby optimizing the high-performance cement-based grout. The levels of each factor are shown in Table 7, and the experimental results are shown in Table 8. Range analysis was used for data processing and analysis of the orthogonal experiments. K i The horizontal symbol is i The sum of the corresponding experimental data; k i for K i / s , s The number of levels in any column; R For the worst, R=max(k i )-min(k i ) The larger the range, the more significant the result; conversely, the smaller the range, the less significant the result.

[0055] Table 7. Table of Experimental Factors and Their Levels Table 8. Results of the Orthogonal Experiment 1.2 Results.

[0056] 1) Gelation time range analysis: The measured data of slurry gelation time are shown in Table 9 and... Figure 1 It can be seen that the water-cement ratio has the most significant impact on the setting time of the slurry, and the order of importance is: water-cement ratio > cellulose > alkali activator > water-reducing agent > defoamer > mineral powder content.

[0057] Table 9. Analysis of the range of gelation time Depend on Figure 1 It can be seen that as the water-cement ratio increases, the gelling time increases continuously, although the rate of increase decreases slightly. There are optimal values ​​for the mineral powder content and defoamer content, which are 55% and 1.2%, respectively. Under the orthogonal experimental design scheme, the gelling time of the grout is controlled between 40 min and 160 min, with the design time consistently above 40 min. This allows for a wide adjustment range, enabling the selection of different gelling time ratios based on actual engineering conditions to meet the needs of the dynamic water grouting process.

[0058] 2) Fluidity range analysis: The results of the slurry fluidity test data are shown in Table 10 and... Figure 2The chart shows that the water-cement ratio has the most significant impact on the fluidity of the slurry, while the mineral powder content has the least impact. The order of importance is: water-cement ratio > cellulose > water-reducing agent > alkali activator > defoamer > mineral powder content.

[0059] Table 10. Analysis of Extremely Poor Liquidity Depend on Figure 2 It can be seen that the six factors—water-cement ratio, mineral powder content, alkali activator, cellulose, water-reducing agent, and defoamer—significantly affect the fluidity of the slurry. With increasing water-cement ratio, the fluidity of the slurry continuously increases, but the rate of increase decreases. The fluidity of the slurry increases with increasing water-reducing agent content, showing an approximately linear change. The addition of alkali activator and cellulose reduces the fluidity of the slurry, and the decrease is significant with increasing content. There are optimal content values ​​for both mineral powder and defoamer, which are 55% and 1.2%, respectively. In terms of slurry flowability, using a higher water-cement ratio and a lower cellulose content can significantly improve the fluidity of the slurry. Based on the above results, the composite slurry fluidity reaches over 20 cm, which can meet the requirements of practical engineering operations.

[0060] 3) Analysis of extremely poor resistance to water erosion: The results of the slurry water erosion test are shown in Table 11 and... Figure 3 The analysis of the charts shows that the water-cement ratio has the most significant impact on the slurry's resistance to water erosion, followed by cellulose, while the alkali activator dosage has the least impact. The order of importance is: water-cement ratio > cellulose > mineral powder dosage > defoamer > water-reducing agent > alkali activator.

[0061] Table 11 Analysis of Extremely Poor Resistance to Explosion Depend on Figure 3 It can be seen that as the water-cement ratio and mineral powder content increase, the water-dispersibility of the slurry gradually decreases. The dispersibility of cellulose and alkali activator increases with increasing content, and the optimal value for defoamer is 1.2%. In terms of water-dispersibility, reducing the water-cement ratio and adding cellulose can significantly improve the water-dispersibility of the slurry. The water-dispersibility of slurries with different combinations varies greatly, and the choice can be made according to the actual project.

[0062] 4) Analysis of the range of stone strength: The strength data of the slurry-formed stone body are shown in Table 12 and... Figure 4 Therefore, it can be seen that the water-cement ratio has the most significant impact on the strength of the slurry aggregate, followed by the amount of alkali activator, and the amount of mineral powder has the least impact. The order of importance is: water-cement ratio > alkali activator > cellulose > defoamer > water-reducing agent > mineral powder.

[0063] Table 12 Analysis of Strength Variation of Grout Stones Depend on Figure 4 It is known that the water-cement ratio is the most significant factor affecting the strength of the cement paste; a higher water-cement ratio results in lower strength. The appropriate water-cement ratio can be selected based on the specific engineering requirements. Alkali activators have a secondary effect on the mechanical properties of hardened cement paste. The dosage of activators positively promotes the strength of the cement paste. Activators act on the cementitious materials, providing calcium hydroxide and increasing the alkalinity of the materials, thus promoting the rapid hydration of slowly reacting substances such as mineral powder, and also providing a greater amount of free SiO3. 2- Plasma is generated, thus forming a gel that facilitates slurry hardening. With increasing cellulose content, the strength of the slurry aggregate decreases. This is because while cellulose can improve the water erosion resistance of cement-based slurry, it also has significant surface activity, generating numerous air bubbles during mixing, thus altering the slurry density and reducing the mechanical properties of the aggregate. Defoamer significantly improves the mechanical properties of the slurry aggregate with increasing dosage. This is because defoamer weakens the bubble film layer through its own properties, causing the bubble film to rupture at a critical thickness, increasing slurry density and enhancing aggregate strength. The effects of mineral powder and water-reducing agent dosages on the strength of the slurry aggregate are relatively insignificant; with increasing dosage, the aggregate strength decreases slightly, with both showing essentially the same effect. From the perspective of aggregate strength, a water-reducing agent dosage of 0.4% is the preferred value.

[0064] 5) Determining the Optimal Scheme: By reasonably adjusting the grout mix proportion and selecting appropriate water-cement ratios and admixture dosages such as cellulose, the strength range of the slurry body can be measured to be 4MPa~15MPa. Considering the grout characteristics and the operability of general grouting equipment, the optimal mix proportion scheme is selected for further experimental research, aiming to optimize the early strength characteristics of the grout by adding an early strength agent, thereby enabling the grout to meet the requirements of rapid grouting. The optimal scheme is applicable to geological conditions of water-rich fault fracture zones, and the mix proportion scheme is shown in Table 13.

[0065] Table 13 Optimal Mixture Proportion Scheme 2. Univariate experimental analysis of early strength agent.

[0066] For fault fracture zones, in addition to meeting strength requirements, it is particularly important to improve their early strength and accelerate their gelation time to shorten the waiting time from grouting reinforcement to excavation. Through the aforementioned orthogonal experimental design, an optimal scheme was proposed for further research. In the optimal scheme, the amount of sulfoaluminate cement is relatively low, and the 7-day strength of the grout is 14.82 MPa and 9.38 MPa, respectively, meeting the grouting strength requirements. The gelation time of the optimal scheme is around 70 minutes, which is relatively long, and the early strength growth is slow. Therefore, it is considered to add admixtures to accelerate the hardening speed of the cement grout, improve its early strength, and shorten the early gelation time. Early strength agents can significantly improve the early strength of the grout and rapidly enhance its early mechanical properties. Triethanolamine, aluminum sulfate, and calcium nitrite were selected as single admixtures and composite admixtures in cement-based optimal grouts, and the applicability of the three early strength agents with the optimal grouts was studied.

[0067] Calcium nitrite dissolves in water and can increase the calcium content. 2+ Ion concentration promotes the precipitation of calcium hydroxide, thereby increasing the production of ettringite and accelerating the hydration and hardening of cementitious grout. Triethanolamine, due to the presence of unshared electrons in its molecular structure, can form relatively stable complexes with metal ions in cementitious grout, thus promoting the formation of ettringite, accelerating the formation of hydration products, and shortening the grout setting and hardening time. Composite agent M combines the advantages of the above-mentioned early-strength agents, accelerating the destruction of the hydration protective film, shortening the induction time, greatly promoting the setting and hardening speed of cement, improving its early mechanical strength, and shortening the setting time.

[0068] The experimental designs were as follows: Group 1: Triethanolamine alone; Group 2: Calcium nitrite alone; Group 3: Composite agent M, prepared by mixing triethanolamine, aluminum sulfate, and calcium nitrite, wherein triethanolamine accounted for 0.03% of the mass of the mixed cement, aluminum sulfate accounted for 1.5% of the mass of the mixed cement, and calcium nitrite accounted for 1% of the mass of the mixed cement. The specific test results for each design are shown in Tables 14 and 15. Figure 5 and Figure 6 .

[0069] Table 14. Settling Time Test Values Table 15 Compressive Strength Test Values From Table 14 and Figure 5It can be seen that both triethanolamine and calcium nitrite can reduce the setting time of the slurry, and this reduction continues with the increase of the dosage of the early-strength agent. The effect of the composite early-strength agent M on the setting time is basically consistent with the trend of the single-dosage group. After the dosage of the composite early-strength agent M exceeds 1%, it shows significantly better properties than other single-dosage groups. When the dosage of each early-strength agent is 2%, compared with the control group, the reduction of triethanolamine and calcium nitrite is 29.33% and 30.67%, respectively, while that of the composite early-strength agent M is 42.67%. The composite early-strength agent M increases the early-strength time by 13.34% and 12% compared with triethanolamine and calcium nitrite, respectively. At the same time, when the dosage is 3% and 4%, the composite early-strength agent M is better than the single-dosage group. Therefore, it can be concluded that the composite early-strength agent is better than triethanolamine and calcium nitrite, indicating that the composite early-strength agent M has good applicability to the selected slurry and can give full play to the early-setting effect.

[0070] When the dosage of composite early-strength agent M is 0.5%, the setting time is reduced by 4% compared to the control group. When the dosage is increased to 3% and 4%, the gelation time is 33 min and 27 min, respectively, which are reduced by 56% and 64% compared to the control group. When the dosage of composite early-strength agent M is 2%, the setting time is reduced by 42.6% compared to the control group, which is the largest reduction, at 29.51%. Therefore, in terms of setting time, a dosage of 2% of composite early-strength agent M is the preferred value.

[0071] From Table 15 and Figure 6 It can be seen that the compressive strength of the composite early-strength agent M increases continuously with the increase of the early-strength agent dosage. When the dosage exceeds 3%, a downward trend occurs, but it is still much stronger than the blank test group. The strength change trend of single-doped triethanolamine and single-doped calcium nitrite is basically similar. With the increase of dosage to 3%, the strength increase is the largest, and then the strength growth is slow and basically remains unchanged. When the early-strength agent dosage is 0.5%, the compressive strength of single-doped triethanolamine and single-doped calcium nitrite is 11.23 MPa and 10.31 MPa, respectively. When the dosage increases to 3%, their compressive strengths are 15.15 MPa and 12.19 MPa, respectively, an increase of 34.91% and 18.24%. When the dosage was 3%, compared to the control group, the strength increases by 49.85% and 20.57% for single-doped triethanolamine and single-doped calcium nitrite, respectively. The composite early-strength agent M was 70.03% greater than that of single-doped triethanolamine and single-doped calcium nitrite, by 20.18 and 49.46 percentage points, respectively. Under other dosage conditions, the composite early-strength agent M was also superior to single-doped triethanolamine and single-doped calcium nitrite, and it reached its optimal value at a dosage of 3%. Therefore, in terms of strength, the composite early-strength agent M is superior to single-doped triethanolamine and single-doped calcium nitrite.

[0072] Based on the above analysis results, taking compressive strength as the main indicator and referring to the setting time control range, it is recommended to use a 2% dosage of composite early strength agent M to improve the early strength of the selected slurry.

[0073] 3. Test on the effect of grouting reinforcement in fault fracture zones.

[0074] To analyze the effect of grouting on the mechanical properties of fractured rock masses, a grouting simulation test was conducted on fault fractured zones, including three working conditions: pore water pressure of 0 MPa, 0.2 MPa, and 0.3 MPa. After the grouting reinforcement test, the grout-reinforced solidified material in the fault fractured zone was cured in a chamber for 3 days and wrapped in plastic wrap for 4 days, for a total of 7 days, before undergoing a uniaxial compression test. Core samples were taken from the consolidated body using a core drilling rig, with a core diameter of 50 mm. Core sampling was performed in areas with high grouting integrity. See [link to core sampling details]. Figure 7 Three core samples were randomly selected from each grouting test group, and the average value of the data from each group was taken as the result of the uniaxial compressive strength test of the reinforced body.

[0075] Because the surface of the core extracted during actual core drilling is uneven, a grinding machine is used to cut and grind it after core extraction. According to the requirements of rock mechanics test specifications, the height-to-diameter ratio is 2:1 and h=100mm.

[0076] The uniaxial compressive strength test of the reinforced body was conducted on a universal testing machine. Before loading, the loading parameters needed to be set after grinding the specimen. Displacement control was used for loading, with the loading rate set to 1 mm / min. After setting the parameters and placing the core specimen in the center of the loading plate, the loading plate was lowered to approximately 1 mm from the core specimen by controlling the loading plate switch. The loading test was then conducted using a computer-programmed procedure, and the loading process parameters were recorded by computer until the specimen failed. The test data was then exported for analysis.

[0077] During the uniaxial compressive strength test, the stress-strain curve of the stone core sample was recorded, such as... Figure 8 As shown in the figure below, the grouting effect of the fractured rock mass varies with the water pressure in the water-rich fractured zone, but all the stress-strain curves go through the compaction stage, elastic stage, yielding stage and plastic stage.

[0078] Depend on Figure 8As shown in (a), the stress-strain curve under 0.3 MPa water pressure is relatively smooth and regular, exhibiting four distinct stages. In the compaction stage, the strain is small, only 0.3 mm, followed by an elastic stage. During the elastic stage, the stress-strain curve shows an approximately linear increase, and the elastic modulus of the rock mass is calculated to be 1.27 GPa based on this stress-strain curve. When the yield stage is reached, the peak stress is 11.82 MPa, and the strain is 1.05 mm. After the peak stress, the test results in failure, showing a decreasing stress trend. The stress continuously decreases with increasing strain, and the decreasing trend becomes increasingly pronounced, with the magnitude gradually increasing. The strength decreases relatively slowly after the peak, with significant ductility and a residual strength of approximately 2 MPa. These phenomena indicate that the failure under 0.3 MPa water pressure is primarily brittle failure, with good ductility in the later plastic stage, exhibiting significant deformation capacity, and demonstrating good and reliable grouting effect.

[0079] Depend on Figure 8 As shown in (b), the stress-strain curve under 0.2 MPa water pressure exhibits significant fluctuations, but still shows four distinct stages of change. The main reason for this is that during the grouting reinforcement test, uneven mixing of the grout or the presence of air bubbles trapped inside the reinforced body during grout diffusion led to localized weakening during uniaxial compression, resulting in slight oscillations and shifts in strength. The peak strength was 10.22 MPa, corresponding to a strain of 1.2 mm. After the peak strength, the stress decreased sharply to the residual strength, which was approximately 2.4 MPa, indicating significant brittle failure. This phenomenon may be due to the lengthy compaction phase in the early stages of the test, which allowed for the complete densification of internal micropores and air bubbles, resulting in a denser structure. After reaching the peak strength, the brittle failure characteristics became more pronounced, and the stress changed rapidly after the peak strength. These phenomena indicate that the failure under 0.2 MPa water pressure was significantly brittle, with relatively small deformation and good overall rigidity. The calculated elastic modulus for this condition was 1.13 GPa.

[0080] Depend on Figure 8As shown in (c), the stress-strain curve fluctuates significantly under 0 MPa water pressure, and the four stages of change are quite complex. A stress step occurs in the elastic stage. The reason for this is that there is no pressure inside the model box during grouting, and the high grouting pressure results in large pores in the grouted solid, leading to random grout diffusion and low density. After the stress step compaction, the strength increases sharply, with a strain of approximately 1.9 mm at the stress step, indicating a relatively large strain. Calculations based on the elastic stage show an elastic modulus of 0.51 GPa under this condition. The peak strength is 9.46 MPa, corresponding to a strain of 2.8 mm. After the peak strength, the stress decreases sharply to another yield step. This is because the solid contains some nodule areas, leading to strength concentration and the formation of a residual stress step. The final residual strength value is approximately 2.0 MPa, gradually stabilizing. The above phenomena indicate that the pressure during grouting under 0MPa water pressure should not be too high, and the grouting rate should not be too fast. Otherwise, the grout may spread widely and become more random, which may result in voids in the reinforced body that are not filled by the grout, and the grouting effect will be slightly worse.

[0081] The compressive strength of the grouting solid is one of the key indicators for evaluating the grouting effect, and its strength varies under different water head heights. Analysis of the above figures shows that the peak compressive strength at 0.3 MPa water pressure is 11.82 MPa. Under 0.2 MPa and 0 MPa water pressures, the uniaxial compressive strengths are 10.22 MPa and 9.46 MPa, respectively. The compressive strength at 0.3 MPa water pressure is approximately 15.66% and 24.95% higher than that at 0.2 MPa and 0 MPa water pressures, respectively, and the strength at 0.2 MPa water pressure is 8.04% higher than that at 0 MPa water pressure. With increasing grouting water pressure, the compressive strength of the solid continuously increases, and the rate of increase continues to expand. This indicates that when using a superior grouting slurry to reinforce fault fracture zones under high water pressure, the slurry exhibits excellent water dispersibility. It also demonstrates that grouting pressure significantly impacts the grouting effect; lower-pressure grouting schemes can be used in formations with lower pressure to mitigate the porosity and defects generated by high-pressure grouting. When formation water pressure is high, high-pressure grouting methods can be employed to allow more grout to penetrate into micro-fractures, increasing the density of the fractured rock mass. High-pressure compaction and compression of the fractured formation can achieve excellent grouting results.

[0082] After the fault fracture zone is reinforced with water-dispersible grout, the shear strength of the grouted body needs to be determined during tunnel stability analysis. Therefore, core samples were tested again, and the shear strength results of the grouted body under stress in different directions are shown in Table 16. Figure 9 As shown.

[0083] Table 16 Shear Strength of Grouted Solids Depend on Figure 9 The stress variation and fitting curve of shear strength show that the shear strength of the grout increases linearly with the continuous increase of normal stress. From the above analysis, the linear fitting curve is... The linear fit has a high correlation, with a correlation coefficient of R0. 2 The value was 0.9951, indicating a reliable and good fitting effect. Considering the intercept and slope of the fitting curve based on the strength change data obtained from shear tests as the cohesion and internal friction angle of the grouting solid, the internal friction angle of the grouting solid was found to be 36.9°, and the cohesion was 0.36 MPa.

[0084] 4. Analysis of seepage pressure distribution characteristics.

[0085] To understand the changes in pore water pressure around the grouting pipe within the fractured zone of the water-rich fault during grouting, continuous pore water pressure monitoring was conducted. This section focuses on analyzing the seepage pressure distribution characteristics during grouting at water pressures of 0.2 MPa and 0.3 MPa. Through integrated data analysis, the arrangement of piezometer measuring points exhibits a roughly symmetrical pattern. Here, measuring points M7, M2, and M1 at a water pressure of 0.20 MPa are selected for characteristic analysis; see [link to relevant documentation] for details. Figure 10 Other piezometers take the stable maximum value to obtain the piezoresistive pressure distribution, as shown below. Figure 11 As shown.

[0086] In the experiment, the entire grouting process was dynamic. Before data acquisition, the data from the data acquisition instrument were all at 0 kPa after automatic balancing. After the initial pressure application, the changes in the data acquisition instrument and the seepage pressure gauge were reasonable. There were certain fluctuations in grouting during the experiment, especially when the seepage pressure collected by the static data acquisition instrument reached three-quarters of the final pressure. Even when the final grouting pressure was reached, the data still fluctuated.

[0087] analyze Figure 11 It can be seen that when the grouting pressure is 0.3 MPa, the pressure distribution characteristics are basically the same as when the grouting pressure is 0.2 MPa. The seepage pressure value increases significantly with the continuous increase of the grouting pressure, showing a significant upward trend. The closer to the grouting pipe, the higher the seepage pressure. This is because there is still a certain distance between the grouting pipe and the piezometer measuring point, and the fractured rock mass generates viscous resistance of the grout. The farther away from the grouting pipe, the slower the increase in seepage pressure, and the increase rate gradually decreases. The pressure values ​​at the same distance from the grouting pipe and the piezometer measuring point are almost the same, showing a symmetrical distribution trend on the left and right sides of the grouting pipe. Comparing the data of the upper and lower parts of the grouting pipe, the pressure value of the upper part of the grouting pipe fluctuates more than that of the lower part, but not significantly. This may be because when the grout is squeezed out along the perforated hole, the squeezing pressure gradually decreases as the perforation hole of the grouting perforation pipe extends. During the squeezing process, the grout mainly diffuses radially along the grouting perforation pipe, and due to gravity, the grout has a certain downward seepage tendency. The final value data of the piezometer are summarized below. Figure 12.

[0088] Analyzing the specific experimental data, when the grouting pressure was 0.2 MPa, the final seepage pressure at measuring point C7 was 369.7 kPa, which was 66.6 kPa and 103.4 kPa higher than measuring points C2 and C3, respectively, representing increases of 21.97% and 38.83%. When the grouting pressure was 0.3 MPa, the pressure at measuring point C7 increased by 12.18% and 18.12% compared to C2 and C3, respectively. Analyzing the data values ​​on both sides of the grouting pipe, the error values ​​were all around 1%, indicating that the grouting pipe basically exhibited a left-right symmetrical trend. The grouting pressure was 0.2 MPa. At a pressure of 0.3 MPa, the difference between measuring point C9 and measuring point C7 was 1.57%, the difference between measuring point C8 and measuring point C2 was 9.63%, and the difference between measuring point C3 and measuring point C1 was 16.01%. At a grouting pressure of 0.3 MPa, the error between the upper and lower measuring points of the grouting pipe was within 10%, and the final pressure value showed some variation. At a grouting pressure of 0.2 MPa, the difference between the upper and lower measuring points was larger than that at 0.3 MPa. This may be due to the existence of a certain boundary effect in the model test chamber, which gradually decreases as the grouting pressure increases.

[0089] Based on the above description of characteristics and data analysis, the grouting process is consistent with the actual grouting situation, indicating that the grouting test process has good rationality and scientific validity.

[0090] To explore the specific situation of the grout filling the internal pores of the reinforced body, analyze the connection between the grout and solid particles, and thus characterize the grouting reinforcement effect, the contact between the magma and rock interfaces was observed by using slice diagrams and model reconstruction to analyze the internal reinforcement mechanism of the grouting reinforced body from a microscopic perspective.

[0091] Figure 13 This is a CT scan cross-section of the grouting reinforced body. Analysis of the image shows that the grout-rock interface within the reinforced body is tightly connected, with no obvious voids, inclusions, cracks, looseness, or stratification. The grout is evenly distributed between the rock masses, forming a good contact zone throughout the circumference. No segregation or stratification occurred during the grouting process, from completion to hardening and reaching its final strength, indicating good overall stability. While the presence of some argillaceous gravel within the rock mass could potentially cause loose bonding between the grout and the rock, forming voids in the reinforced area, CT scan analysis shows no large voids, indicating good compatibility between the grout and the rock mass and the argillaceous gravel. Qualitative analysis of the cross-section reveals spherical pore structures in some areas of the grout. This is mainly due to uneven mixing during the experiment, which prevented the defoamer from fully functioning, causing the air bubbles originally present in the grout to solidify and harden, resulting in spherical pores. However, these trace pores did not form interconnected fracture structures and had little impact on the overall grouting reinforcement effect.

[0092] Figure 14This is a reconstructed image of the CT scan results for grouting reinforcement. Analysis of the CT scan reconstruction results shows that the grout has a significant encapsulating effect on the rock mass, and the rock mass is evenly distributed within the grout. This fully demonstrates the grout's excellent resistance to water dispersion, its resistance to dilution by groundwater, and its ability to effectively fill the voids in the fractured rock mass. Furthermore, the grout's contact with the fractured rock fragments is tight. From a microscopic perspective, this indicates that the proposed preferred grout has good usability in water-rich fault fracture zones and provides excellent reinforcement for fractured rock masses.

[0093] 5. Numerical simulation analysis of slurry diffusion characteristics in fractured zones using PFC.

[0094] 5.1 Assumptions of the Particle Flow Method

[0095] During the experiment, the fractured rock mass was a discontinuous granular medium. To better investigate the diffusion state of the grout under the supporting working conditions, numerical simulation was performed using the particle flow software PFC based on discrete element theory. Circular spheres were used to simulate the rock mass being grouted. An explicit calculation method was employed to observe the diffusion effect caused by the grout's compression and infiltration within the rock mass. The results were compared macroscopically with those from the grouting test, reflecting the phenomena of grout infiltration and diffusion during the experimental process. The particle flow numerical calculation method is based on the following fundamental assumptions:

[0096] (1) The rock particles in the fault fracture zone are regarded as small balls in PFC.

[0097] (2) The granules are rigid bodies, that is, the deformation of the granules themselves is ignored.

[0098] (3) The contact between particles is point contact.

[0099] (4) Ignore the overlap effect of the particles during the calculation process.

[0100] (5) Different mechanical parameters are set according to different contact modes, without considering the cohesive force between particle flows.

[0101] (6) Boundary displacement is not considered, and the displacement of the boundary caused by the collision of the small ball is ignored.

[0102] 5.2 PFC Numerical Model Construction.

[0103] Based on the size of the grouting test formation simulation platform, the particle flow model boundary was determined using a scale proportional to the model test. A three-dimensional model was used for grouting simulation design, with dimensions of length × width × height = 1.1m × 0.6m × 0.5m. The `ballgenerate` command was used to generate small spheres. Spheres of different diameters were generated according to the parameters of the fractured rock mass being grouted in the test, without considering overlap between spheres; the particles were assumed to be uniform. Both the ball-ball contact mode and the ball-facet contact mode in the model adopted the liner model. The linear contact model specifies an elastic relationship between relative displacement and contact force, and a corresponding relationship exists between stiffness and force in the model. This model was used to simulate the fractured rock mass being grouted. The numerical modeling results are shown in [link to numerical model]. Figure 15 .

[0104] During the simulation, the `wall` command was used to establish a steel plate constraint around the perimeter. Water pressure was simulated using servo pressurization, allowing adjustment of the water pressure experienced by the particles during the calculation. This simulation was conducted under water-pressure-free engineering conditions. Simultaneously, the `wall geometry` command was used to create the grouting pipe model region, and the small spheres within the grouting pipe region were deleted. The grouting pipe was created using the `cylinder` command, forming the grouting pipe region. In the model, `domain` represents the model box size, and the command `model domaincondition stop` was set to stop the velocity of the small spheres upon collision with the `wall`, simulating the adhesion effect of the grout against the wall. The grout was simulated using rigid spheres with sufficiently small radii. The grouting speed was controlled by generating spheres with different velocities within the grouting pipe region. The grouting rate was determined by the grouting pressure, utilizing the relationship between the grouting rate and the initial velocity of the grout particles. The numerical calculation parameters used in the grouting test process were adopted, and micro-parameter calibration and conversion were performed with reference to relevant literature. The modeling parameters are shown in Table 17 below.

[0105] Table 17 Material Parameters for Numerical Simulation 5.3 Analysis and comparison of grout diffusion state.

[0106] Grout diffusion state analysis: The grout diffusion results were analyzed using a particle flow numerical calculation model. With continuous grouting circulation, grout particles permeate within the simulated particles of the fractured rock mass, filling the pores of the faulted fractured rock mass and further compacting the fractured rock mass by occupying space. At the start of grouting, the grout particles have a high velocity, being ejected and extruded along the grouting pipe area, diffusing rapidly to the surrounding area. As the distance from the grouting pipe area increases, the velocity gradually decreases, while the displacement gradually increases. This is basically consistent with the initial state of grouting during actual grouting tests. The grouting situation is shown in [the diagram]. Figure 16As small spherical particles are continuously generated within the grouting pipe area and extruded with a uniform initial velocity, they diffuse outwards, gradually filling the pores left by the fractured rock mass, thus compacting the rock mass and forming a coexistence of rock spherical particles and grout spherical particles. Through parameter construction, the viscosity coefficient of the grout spherical particles is set to simulate the velocity attenuation effect when the grout contacts the rock mass, simulating the resistance and viscosity force generated by the rock mass on the grout during grout infiltration. Observation of the overall grout diffusion shows that the grout diffusion state is basically consistent with the morphology of the grout-reinforced body removed during the grouting test. In the grouting termination state, the grout spherical particles are concentrated in the area near the grouting pipe, with some distributed in areas farther away, forming the grout-reinforced compacted zone C1, the grout-reinforced weakened zone C2, and the grout-reinforced edge zone C3, respectively. Due to their varying sizes, a small portion of the grout particles adhere to the wall, forming the adsorption zone C4. This state is consistent with the reinforcement situation encountered during the excavation of the reinforced body in the grouting test. The grouting-reinforced dense zone C1 is the effective reinforcement zone. This zone has a good reinforcement state and can form a high-strength, complete reinforced body. The grouting-reinforced weakened zone C2 has a relatively weak reinforcement effect and may have some pores that affect the reinforcement effect. Core sampling in this zone is prone to producing defective core samples. The grouting-reinforced edge zone C3 is the outermost edge of the grout extension. At this point, the grout distribution is relatively sparse, which can generate a small amount of cementing force, but core sampling is more difficult. This is basically consistent with the actual grouting excavation and core sampling situation.

[0107] Analysis of grout diffusion state: By observing the filling state between the grout spheres and the rock mass spheres, it can be found that the grout fills the spaces between the rock masses, seeps outward through the rock mass fissures, and some spheres are closely attached to the periphery of the rock mass spheres, which is roughly the same as the actual grout diffusion process. The grout diffusion lengths during the experimental grouting and numerical simulation grouting processes are summarized as follows: Figure 17 As shown. Due to the basic assumptions made in the numerical calculations, there are certain errors compared to the actual grouting process, with the basic error being within 15%. While some displacement changes in the numerical simulation are somewhat idealized, the overall grout diffusion characteristics and diffusion patterns are basically consistent with the simulation. This allows for a good comparison, confirming that the experimental process meets the theoretical grouting state and verifying the scientific validity and effectiveness of the grouting experiment.

[0108] The above description is merely a preferred embodiment of the present invention, and the specific embodiments described above are not intended to limit the present invention. Various modifications and variations can be made within the scope of the technical concept of the present invention. All refinements, modifications, or equivalent substitutions made by those skilled in the art based on the above description are within the scope of protection of the present invention.

Claims

1. A composite grouting material for water-rich fault fracture zones, characterized in that, Including water, compound cement, slag, activator, anti-water dispersant, water-reducing agent and defoamer; The water-cement ratio of the water to the composite cement is 0.8~1.2∶1; The amount of slag added accounts for 40% to 70% of the mass of the compound cement; The amount of the activator added is 4% to 6% of the mass of the compound cement; The amount of the anti-water dispersant agent added accounts for 0.6% to 0.8% of the mass of the compound cement; The water-reducing agent is added at a rate of 0.3% to 0.5% of the mass of the compound cement. The amount of defoamer added is 1% to 1.4% of the mass of the compound cement; The compound cement is obtained by mixing silicate cement and sulfoaluminate cement in a mass ratio of 3 to 2:

1.

2. The composite grouting material for water-rich fault fracture zones according to claim 1, characterized in that, The water-dispersible agent is methyl hydroxyethyl cellulose.

3. The composite grouting material for water-rich fault fracture zones according to claim 1, characterized in that, The defoamer is a polyether-modified organosilicon liquid defoamer with a pH value of 6-8.

4. The composite grouting material for water-rich fault fracture zones according to claim 1, characterized in that, The slag is S95 mineral powder.

5. The composite grouting material for water-rich fault fracture zones according to claim 1, characterized in that, The activator is composed of calcium hydroxide and calcium silicate in a mass ratio of 1 to 1.2:

1.

6. The composite grouting material for water-rich fault fracture zones according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent.

7. The composite grouting material for water-rich fault fracture zones according to claim 1, characterized in that, The composite grouting material also includes an early-strength agent, which accounts for 0.5% to 4% of the mass of the composite cement.

8. The composite grouting material for water-rich fault fracture zones according to claim 7, characterized in that, The early strength agent is prepared by compounding triethanolamine, aluminum sulfate and calcium nitrite in a mass ratio of 0.02~0.04:1.2~1.5:

1.

9. A method for preparing a composite grouting material for water-rich fault fracture zones as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Weigh each raw material according to its mass percentage; After adding water-reducing agent and alkali activator to water and stirring, then adding compound cement and slag and stirring, then adding defoamer and anti-water dispersing agent and stirring, a composite grouting material is obtained. Alternatively, water-reducing agent and alkali activator can be added to water and stirred, then compound cement and slag can be added and stirred, followed by defoamer, anti-water dispersing agent and early strength agent, and stirred to obtain composite grouting material.

10. The application of the composite grouting material for water-rich fault fracture zones as described in any one of claims 1 to 8 in the reinforcement and repair treatment of water-rich fault fracture zones.

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