Flexible anti-seepage shield tunnel synchronous grouting material and preparation method and application thereof

Abstract

The present application belongs to the field of shield tunnel engineering materials and underground structure vibration reduction and isolation technology, and relates to a flexible anti-seepage shield tunnel synchronous grouting material, a preparation method and application thereof. The material takes emulsified asphalt as a continuous phase, is compounded with cement, fine aggregate, water reducing agent and special soil (bentonite), and further introduces a cellulose stabilizer. Modified emulsified asphalt is used as necessary, and modified toughening components for asphalt phase can be compounded. Compared with the prior art, the material can realize continuous and dense backfilling and naturally form an excellent water-tight barrier after being injected into a shield tail gap. Through stable components and dispersion process, flocculation, segregation and bleeding are inhibited, and the slurry has good pumpability, diffusivity and suitable setting time within the construction window. After the slurry solidifies, a composite grouting layer is formed, which can effectively absorb and dissipate energy under seismic or uneven deformation conditions, provide cushioning for segments and reduce stress concentration, so as to realize the synergistic improvement of shock absorption and crack resistance and long-term anti-seepage.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel engineering materials and underground structure vibration reduction and isolation technology, and in particular to a flexible seepage-proof shield tunnel synchronous grouting material, its preparation method and application. Background Technology

[0002] Due to its advantages such as high construction efficiency and minimal ground disturbance, the shield tunneling method has been widely used in underground engineering projects such as urban rail transit, integrated utility tunnels, and tunnels crossing rivers and seas. After the shield advances and the segments are assembled, an annular shield tail gap is formed on the outside of the segments. If this gap is not backfilled in a timely, uniform, and dense manner within the construction window, it can easily lead to ground relaxation and surface subsidence, uneven stress on the segments, and deviations in their orientation. It can also provide potential channels for subsequent leakage. Therefore, the synchronous grouting material must simultaneously meet the requirements of being pumpable, diffusible, having low bleeding, and hardening in a timely manner. Existing synchronous grouting materials are mostly cement-based systems or cement-water glass and other fast-setting systems. Although the raw materials are readily available and the early strength development is relatively fast, the elastic modulus after curing is high, the overall rigidity is relatively high and the brittleness is large. Under the conditions of seismic action, differential settlement or uneven deformation, stress concentration is easily generated and cracking and interface debonding are induced. The seismic energy dissipation capacity is insufficient, which leads to the degradation of durability and leakage risk. At the same time, in order to obtain sufficient fluidity, the water-cement ratio is often increased or a large amount of admixtures are introduced, resulting in bleeding segregation, incomplete filling and performance fluctuation. The fast-setting system is also sensitive to temperature and proportion, and the on-site controllability and reproducibility are poor.

[0003] To adapt to high-intensity earthquake zones and vibration-sensitive scenarios, shield tunnels urgently need a backfill layer that forms on the outside of the tunnel segments that is "supportable, deformable, and energy-dissipating" in order to reduce the input of ground motion and traffic vibration and improve the overall structural toughness. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems by providing a flexible seepage-proof shield tunnel synchronous grouting material, its preparation method, and its application. Specifically, it is an emulsified asphalt-cement composite grouting material for use behind the synchronous grouting wall of a flexible seepage-proof shield tunnel, along with its preparation method and application. The emulsified asphalt-cement composite synchronous grouting material proposed in this invention uses emulsified asphalt as the continuous phase. The asphalt phase naturally possesses watertight properties for waterproofing film formation and pore sealing, forming a continuous and stable seepage barrier within the tail gap. Simultaneously, through the synergistic effect of viscoelastic energy dissipation from the organic phase and cementitious load-bearing capacity from the inorganic phase, the hardened body exhibits moderate strength, lower elastic modulus, and stronger deformation adaptability, providing buffer energy dissipation and inhibiting cracking under seismic and uneven deformation conditions. Furthermore, by combining cellulose stabilizers, special soils, and dispersion processes for stable compatibility control, flocculation, segregation, and bleeding can be effectively suppressed, ensuring pumpability and diffusion performance during construction and achieving continuous and dense filling of the tail gap, thus balancing flexible earthquake resistance and long-term watertight durability.

[0005] The objective of this invention is achieved through the following technical solution: The first objective of this invention is to provide a flexible anti-seepage shield tunnel synchronous grouting material, the basic components of which are: emulsified asphalt, cement, fine aggregate, water-reducing agent, and special soil, and further include a cellulose stabilizer as a stabilizing and regulating component.

[0006] Furthermore, the special soil includes bentonite.

[0007] Furthermore, the components of the synchronous grouting material satisfy the following mass ratio relationship: Cement / Emulsified Asphalt = 35%–60% Fine aggregate / emulsified asphalt = 40~60%, Water-reducing agent / cement ratio: 0.2~1.0% Bentonite / emulsified bitumen = 2~6%.

[0008] More preferably, the components of the synchronous grouting material satisfy the following mass ratio: cement / emulsified asphalt = 35%~60%; fine aggregate / emulsified asphalt = 50%; water-reducing agent / cement = 0.5%; bentonite / emulsified asphalt = 4.0%.

[0009] Furthermore, the cellulose stabilizer is added at a dosage of 0.05% to 2.0% based on the mass of emulsified asphalt (cellulose stabilizer / emulsified asphalt = 0.05% to 2.0%), which is used to improve the stability and interfacial compatibility of the emulsion phase and inhibit flocculation, segregation and bleeding, thereby improving the batch consistency of the on-site mixing and pumping process and enhancing the compactness and water tightness of the filling.

[0010] Furthermore, the synchronous grouting material uses emulsified asphalt as the continuous phase and cement as the cementitious phase.

[0011] Furthermore, the emulsified asphalt continuous phase possesses natural seepage-proof properties such as waterproof film formation and pore sealing. Through the dispersion regulation of water-reducing agents and the thickening and stabilization of special soils, the synergy between fluidity and anti-segregation stability within the construction window is achieved, and the hardened body maintains moderate strength, low elastic modulus, and viscoelastic energy-dissipating characteristics. On this basis, cellulose-based stabilizers are further introduced to enhance the stability and interfacial compatibility of the emulsified phase, inhibit flocculation and segregation bleeding, and asphalt phase modification toughening components can be optionally added to construct a multiphase energy-dissipating structure. If necessary, tensile crack-resistant fibers and / or self-healing components can be optionally added to improve crack resistance and long-term water tightness.

[0012] Furthermore, the emulsified asphalt is unmodified emulsified asphalt or modified emulsified asphalt.

[0013] Furthermore, the special soil also includes red clay; by mass ratio, red clay / emulsified asphalt = 1~5%, preferably red clay / emulsified asphalt = 1.0%~3.0%. The introduction of red clay into the special soil is used to further regulate the thixotropy, anti-bleeding stability and structural recovery ability under pumping shear of the system.

[0014] Furthermore, the cement is PO42.5 ordinary Portland cement.

[0015] Furthermore, the fine aggregate is natural quartz sand with a mesh size of 60-110.

[0016] Furthermore, the synchronous grouting material also includes vitrified microspheres; the vitrified microspheres, based on emulsified asphalt, are added at a concentration of 5% to 15% by mass.

[0017] Furthermore, natural quartz sand can be compounded with vitrified microspheres to reduce the elastic modulus of the hardened body and improve its deformation adaptability.

[0018] Furthermore, the water-reducing agent is one or more of the following: naphthalene-based water-reducing agent, polycarboxylate-based water-reducing agent, melamine-based water-reducing agent, and aminosulfonic acid-based water-reducing agent.

[0019] Furthermore, the cellulose stabilizer includes carboxymethyl cellulose and / or cellulose ether.

[0020] Furthermore, the unmodified emulsified asphalt is one or more of anionic emulsified asphalt, cationic emulsified asphalt, and nonionic emulsified asphalt.

[0021] More preferably, the unmodified emulsified asphalt is a cationic slow-cracking fast-curing emulsified asphalt with a solid content greater than or equal to 55%.

[0022] Furthermore, the modified emulsified asphalt is a modified emulsified asphalt obtained by secondary emulsification and shearing composite of thermally modified matrix asphalt and stable emulsion, in order to improve the continuous phase's resistance to demulsification, segregation and batch stability under high powder impact and pumping shear conditions.

[0023] Furthermore, the stabilized emulsion includes special soil, emulsifier, and cellulose stabilizer.

[0024] Furthermore, in the stabilized emulsion, the mass ratio of special soil, emulsifier and cellulose stabilizer is (10-20):(2-6):1.

[0025] Furthermore, the mass ratio of the thermally modified matrix asphalt to the stabilized emulsion is (60-70):(40-30).

[0026] Furthermore, the thermally modified base asphalt is petroleum asphalt AC90.

[0027] Furthermore, the bentonite is sodium-based bentonite.

[0028] Furthermore, the synchronous grouting material also includes an asphalt phase modification and toughening component; the asphalt phase modification and toughening component, based on emulsified asphalt, has a content of 1% to 9% by mass fraction.

[0029] Furthermore, the asphalt phase modified toughening component is selected from one or more of SBS, rubber particles, polyether polyols, and nano-rubber powder.

[0030] Furthermore, the asphalt phase modification toughening component is preferably premixed with emulsified asphalt before being added as powder to construct a multiphase energy-dissipating toughening structure and improve seismic energy dissipation and crack resistance.

[0031] Furthermore, the synchronous grouting material also includes tensile crack-resistant fibers; the tensile crack-resistant fibers, by mass fraction based on cement, are added at a level of 0.05% to 0.5%. These tensile crack-resistant fibers are used to improve the crack resistance and toughness of the hardened body and reduce the risk of micro-crack penetration, thereby enhancing long-term seepage prevention reliability.

[0032] Furthermore, the tensile-crack-resistant fiber is one or more of polypropylene fiber, PE fiber, polyvinyl alcohol fiber, and alkali-resistant glass fiber.

[0033] Furthermore, the synchronous grouting material also includes a self-healing component; the self-healing component, based on cement, is added at a concentration of 1% to 10% by mass.

[0034] Furthermore, the self-healing component is selected from one or more of hollow glass fibers, acetal polymer solutions, and pozzolanic silicate cement. The self-healing component is used to enhance the self-sealing ability of microcracks and long-term watertightness.

[0035] Furthermore, the acetal polymer solution is a polyvinyl butyral (PVB) solution.

[0036] The second objective of this invention is to provide a method for preparing a flexible seepage-proof shield tunnel synchronous grouting material, the method comprising the following steps: (1) Raw material preparation: Weigh the components of the synchronous grouting material according to the proportion; (2) Pre-dispersion and stabilization of continuous phase: Water-reducing agent is added to emulsified asphalt, and after stirring and dispersing, cellulose stabilizer is added and stirring is continued to obtain a continuous phase system; (3) Premixing and adding powder: After the cement and fine aggregate are premixed evenly, they are added in batches to the continuous phase system obtained in step (2). First, stir at low speed, then switch to medium and high speed to obtain a mixed system. (4) Special soil stabilization treatment: Add special soil to the mixture obtained in step (3) and stir continuously to obtain slurry, which is the synchronous grouting material.

[0037] Further, before step (1), the modified emulsified asphalt can be prepared by adding special soil, emulsifier and cellulose stabilizer to the aqueous phase to prepare a stable emulsion. The base asphalt is thermally modified and then subjected to secondary emulsification and shearing compounding with the stable emulsion to obtain modified emulsified asphalt, which is then used as the continuous phase raw material for subsequent mixing.

[0038] Further, step (1) specifically includes the following process: when modified emulsified asphalt is used, weigh the modified emulsified asphalt, cement, fine aggregate, water-reducing agent, and the special soil and / or cellulose stabilizer that need to be added; when modified emulsified asphalt is not used, weigh the emulsified asphalt, cement, fine aggregate, water-reducing agent, special soil, and cellulose stabilizer; if necessary, weigh the asphalt phase modified toughening component, tensile crack-resistant fiber, and / or self-healing component. The special soil and cellulose stabilizer introduced during the preparation of the modified emulsified asphalt are included in the total amount of the corresponding components in the final synchronous grouting material, and the subsequent addition amount is determined according to the difference between the target ratio and the amount introduced.

[0039] Furthermore, in step (2), the water-reducing agent is added dropwise, and after addition, the mixture is continuously stirred until the system is uniform, so as to reduce the cohesive resistance of the mixing system and improve the fluidity stability.

[0040] Further, step (2) specifically includes the following process: placing the emulsified asphalt in a pre-dispersion container and starting the stirring, adding the water-reducing agent and dispersing it fully, then adding the cellulose stabilizer and continuing stirring until a uniform and stable continuous phase system is formed; when using asphalt phase modified toughening components, it is preferable to premix them with the emulsified asphalt continuous phase first.

[0041] Furthermore, in step (3), the low-speed stirring rate is 300-600 rpm, and the medium-high speed stirring rate is 800-1200 rpm.

[0042] Furthermore, in step (3), the medium-high speed mixing time is not less than 2 minutes. The medium-high speed mixing time after cement and fine aggregate are added to the emulsified asphalt continuous phase is not less than 2 minutes, so as to ensure that the powder is fully wetted and uniformly dispersed and to reduce the performance dispersion caused by agglomeration.

[0043] Furthermore, in step (3), the total time for low-speed stirring and medium-high-speed stirring is 2 to 10 minutes.

[0044] Further, step (3) specifically includes the following process: after the cement and fine aggregate are pre-dry mixed evenly, they are added in batches to the continuous phase system obtained in step (2). First, the powder is fully wetted by low-speed stirring, and then the stirring is switched to medium-high speed for no less than 2 minutes to make the cement and fine aggregate evenly dispersed. When a self-healing component is used, it is preferred to add it after dry mixing with cement / fine aggregate.

[0045] Furthermore, in step (4), the continuous stirring time is 3 to 15 minutes.

[0046] Further, step (4) specifically includes the following process: adding special soil to the system and stirring continuously for no less than 3 minutes until the slurry is uniform and there is no obvious agglomeration or segregation.

[0047] Furthermore, the total mixing time of the raw materials is no less than 5 minutes, and a mixing regime combining low-speed wetting dispersion and medium-high-speed homogenization dispersion is adopted to reduce agglomeration and improve batch consistency.

[0048] Furthermore, when the synchronous grouting material includes an asphalt phase modified toughening component, the asphalt phase modified toughening component is premixed with the emulsified asphalt before the water-reducing agent is added to the emulsified asphalt.

[0049] Furthermore, when the synchronous grouting material includes tensile crack-resistant fibers, the tensile crack-resistant fibers are preferably introduced slowly and evenly in step (2) while the continuous phase is under low-speed stirring. Specifically, the tensile crack-resistant fibers are introduced in step (2) as follows: while the emulsified asphalt continuous phase is under low-speed stirring, the tensile crack-resistant fibers are slowly added in small amounts and evenly, and stirring is continued until the fibers are fully wetted and there are no visible fiber agglomerations. Then, the cement and fine aggregates in step (3) are pre-dry mixed evenly and added in batches. The criterion for complete dispersion is that there are no visible fiber agglomerations and no floating fiber bundles in the grout.

[0050] Furthermore, when the synchronous grouting material includes a self-healing component, the self-healing component, cement, and fine aggregate are pre-dry mixed evenly.

[0051] The third objective of this invention is to provide an application of a flexible seepage-proof shield tunnel synchronous grouting material, which is used for synchronous grouting backfilling of the shield tail voids on the outer side of the shield tunnel segments. Furthermore, the application includes the following process: Synchronous grouting material is used for synchronous grouting backfilling of the shield tail gap outside the shield tunnel segment. After being injected into the shield tail gap outside the shield tunnel segment, it forms a continuous and dense filling layer and a watertight barrier is formed by the asphalt phase. After hardening, it constitutes a composite grouting layer with both load-bearing capacity and flexible energy dissipation characteristics and good watertightness.

[0052] Furthermore, before using the synchronous grouting material for synchronous grouting backfilling of the shield tail voids on the outside of the shield tunnel segments, degassing and pressure stabilization can be selected. Specifically, the process includes the following: In order to reduce pumping pulsation and pore defects caused by air entrapment, the grout is depressurized, degassed, and stabilized before discharge of the synchronous grouting material.

[0053] Furthermore, degassing is carried out within the range of -0.25 to -0.35 MPa to reduce air entrainment and improve pumping stability and the compactness of the hardened body, thereby further enhancing water tightness.

[0054] Furthermore, the thickness of the shield tail void in the synchronous grouting application is 8-20cm. After the grouting hardens, a continuous composite layer is formed on the outside of the segment, which provides energy-dissipating buffer under earthquake and uneven deformation conditions and forms a stable watertight barrier based on the asphalt phase, thereby achieving a synergistic improvement in seismic energy dissipation and seepage prevention and watertightness.

[0055] Furthermore, the synchronous grouting material meets the workability and stability requirements of grouting behind the shield wall, and the preferred control indicators are: consistency 8-12cm, fluidity 20-25cm, water bleeding rate <5%, and setting time 12-18h.

[0056] The technical concept of this invention is as follows: This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method, and its application. The synchronous grouting material includes at least emulsified asphalt, cement, fine aggregate, water-reducing agent, and bentonite (sodium-based bentonite). The emulsified asphalt is one or more of anionic emulsified asphalt, cationic emulsified asphalt, and nonionic emulsified asphalt, preferably cationic slow-cracking and fast-setting emulsified asphalt. Further, it includes a cellulose stabilizer for emulsified phase stabilization and interfacial compatibility control, and may further include asphalt phase modification and toughening components to improve toughness and energy dissipation capacity. If necessary, it may also include a self-healing component to enhance microcrack self-sealing and long-term watertightness. Furthermore, it may include tensile crack-resistant fibers to reduce the risk of hardened body cracking and enhance anti-seepage reliability.

[0057] (1) Parameter range of key component allocation ratio: The synchronous grouting material is based on the quality of emulsified asphalt and meets the following mass ratios: cement / emulsified asphalt = 35%~60%; fine aggregate / emulsified asphalt = 50%; water-reducing agent / cement = 0.5%; bentonite / emulsified asphalt = 4.0%. Further, the cellulose stabilizer is preferably carboxymethyl cellulose and / or cellulose ether, and its dosage based on the mass of emulsified asphalt is preferably 0.05% to 2.0%, used to improve the system's anti-flocculation, anti-segregation, and anti-bleeding capabilities and reduce performance drift; the asphalt phase modification toughening component is preferably one or more of SBS, rubber particles, polyether polyol, or nano-rubber powder, and its dosage based on the mass of emulsified asphalt is preferably 0.5% to 15%, used to improve the toughness and energy dissipation capacity of the hardened body and make the elastic modulus easier to control within a range conducive to deformation coordination; the self-healing component is preferably 0.1% to 5% based on the mass of cement, used to improve the self-sealing of microcracks and long-term watertightness; further, the tensile crack-resistant fiber is preferably 0.05% to 0.5% based on the mass of cement, and the tensile crack-resistant fiber is one or more of polypropylene fiber, PE fiber, polyvinyl alcohol fiber, or alkali-resistant glass fiber, used to improve crack resistance and reduce leakage risks.

[0058] (2) Main steps of the preparation method (S1-S5): S1: Weigh the emulsified asphalt and place it in a mixing pot and start stirring. It is preferable to add the water-reducing agent first and make it fully dispersed in the emulsified asphalt. At the same time, introduce the cellulose stabilizer slowly and stir until uniform to form a stable continuous phase system. When using asphalt phase modified toughening components, it is preferable to premix them with the emulsified asphalt continuous phase before adding the powder to ensure that the toughening components are uniformly distributed in the asphalt phase and form a stable viscoelastic energy-consuming phase.

[0059] S2: Add cement mortar and fine aggregate to the emulsified asphalt continuous phase in batches. First, stir at low speed to fully wet the powder, then switch to medium-high speed and continue stirring for no less than 2 minutes to obtain a uniform asphalt-cement premixed slurry.

[0060] S3: Add sodium bentonite to the system and continue stirring for at least 3 minutes until the slurry is uniform and stable, with no obvious agglomeration or segregation; when using self-healing components, it is preferable to add them together with cement / fine aggregate after premixing to improve dispersion uniformity; when using tensile crack-resistant fibers, it is preferable to introduce them by slow dispersion to avoid agglomeration and improve crack resistance.

[0061] S4: For specific applications: obtain flexible seepage-proof shield tunnel synchronous grouting material, transport it to the shield synchronous grouting system, inject it into the outer tail gap of the tunnel segment for grouting, and form a flexible composite grouting layer after hardening; further, in order to improve pumping stability and reduce air-entrapment pore defects, the grout can be depressurized, degassed and stabilized before pumping to improve filling density and enhance water tightness.

[0062] Furthermore, the unmodified emulsified asphalt is BC-1 cationic slow-cracking fast-setting emulsified asphalt with a solid content of 58.7% and a application rate of 0.5-0.6 kg / m³. 2 Further, the cement is preferably PO42.5 ordinary Portland cement. Further, the fine aggregate is preferably natural sand with a mesh size of 60-110 mesh. Further, the bentonite is preferably sodium-based bentonite. Further, the water-reducing agent is preferably one or more of naphthalene-based, polycarboxylate-based, melamine-based, or aminosulfonic acid-based water-reducing agents. Further, it is preferred that the water-reducing agent / cement ratio is 0.5%, and the bentonite / emulsified asphalt ratio is 4.0%. Strength and flexibility are balanced by adjusting the cement / emulsified asphalt ratio to 35%–60% to adapt to different formation permeability and construction window requirements. Simultaneously, anti-segregation stability and energy dissipation capacity are adjustable through cellulose-based stabilizers and / or modified toughening components, and crack resistance and watertight durability are improved through tensile crack fibers and / or self-healing components. Furthermore, the preferred feeding sequence is "continuous phase pre-dispersion (emulsified asphalt + water-reducing agent + stabilizer and / or toughening component) → batch addition of powder (cement and fine aggregate) → special soil stabilization treatment (bentonite)". Furthermore, the preferred mixing time after adding cement is 2–10 min; the preferred mixing time after adding bentonite is 3–15 min; the total mixing time is preferably no less than 5 min to ensure uniformity and stability, and to improve the reproducibility of on-site mixing. Furthermore, to meet the general construction requirements for grouting behind the shield tunnel wall, the grout is preferably controlled as follows: consistency 8–12 cm, fluidity 20–25 cm, bleeding rate <5%, and setting time 12–18 h.

[0063] Compared with the prior art, the present invention has the following advantages: 1) To address the common problems of existing shield tunnel synchronous grouting materials, such as excessive stiffness of the hardened body, insufficient energy dissipation capacity, incoordination between lining and stratum deformation under earthquake or uneven deformation conditions, easy segregation and bleeding of grout, difficulty in balancing workability and stability, and insufficient replicability of on-site processes, this invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method, and its application. This material is based on an emulsified asphalt-cement composite system, with emulsified asphalt as the continuous phase. It utilizes the natural anti-seepage properties of the asphalt phase in waterproof film formation and pore sealing. While ensuring continuous and dense backfilling of the tail gap and the formation of a watertight barrier, it introduces stable components and interfacial compatibility regulation to ensure that the emulsified phase remains uniformly dispersed and inhibits flocculation, segregation, and bleeding under high powder impact and pumping shear conditions. At the same time, asphalt phase modification and toughening components can be optionally added to construct a multiphase viscoelastic energy dissipation structure. If necessary, self-healing components and / or tensile crack-resistant fibers can be added to improve crack resistance and microcrack self-sealing ability, thereby achieving a synergistic improvement in seismic energy dissipation and anti-seepage durability.

[0064] 2) This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method and application. The material has good pumpability and diffusivity within the construction window. After being injected into the tail gap, it hardens to form a grouting layer with certain strength, low elastic modulus and significant viscoelastic energy dissipation. It can provide buffer for the tunnel segments and reduce the risk of stress concentration caused by ground vibration and differential deformation. At the same time, it maintains a continuous and dense watertight structure in the tail gap, inhibiting the formation of leakage channels, thereby improving the adaptability and safety reliability of the flexible anti-seepage shield tunnel under earthquake and uneven deformation.

[0065] 3) This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method and application. It adopts an emulsified asphalt-cement composite system and can further introduce asphalt phase modification toughening components. The hardened body forms a multiphase structure of "cementing load-bearing + viscoelastic energy dissipation + toughening synergy". It has moderate strength and controllable elastic modulus. The material's deformation capacity and energy dissipation capacity are significantly improved. It can provide buffer for the tunnel segments and improve deformation coordination under earthquake or uneven deformation, thereby improving the seismic toughness and service reliability of the structure.

[0066] 4) This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method, and its application. It uses emulsified asphalt as a continuous phase to form a waterproof film structure and seal pores and interfaces, which can build a continuous and stable watertight barrier in the tail gap. At the same time, through the thickening and stabilizing effect of bentonite, the dispersion and regulation of water-reducing agent, and the interfacial compatibility and structural stabilization effect of cellulose stabilizer, the anti-flocculation and anti-segregation ability of the grout is significantly enhanced, the risk of bleeding and segregation is reduced, making the backfill more compact and further improving the long-term watertight durability. In addition, the combination of self-healing components and / or tensile crack-resistant fibers can reduce the risk of microcrack penetration and leakage.

[0067] 5) This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method and application. Based on a clear proportioning window, through continuous phase pre-dispersion, batch wetting and homogenization of powder, and optional degassing and pressure stabilization processes, the material mixing uniformity, pumping stability and batch consistency are improved, enhancing the on-site engineering replicability and construction controllability of the shield tunnel.

[0068] 6) This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method and application. Within the proportion range of this invention, the 28-day unconfined compressive strength of the hardened body can reach 3.44-6.31 MPa, which can meet the support and stability requirements of the shield grouting layer. At the same time, by controlling the flexible phase and toughening phase, the deformation incoordination problem caused by the excessively high modulus of the traditional rigid grouting layer is avoided, and the crack resistance and energy dissipation stability are improved, reducing the risk of leakage in the later stage.

[0069] 7) This invention provides a flexible anti-seepage shield tunnel synchronous grouting material, its preparation method and application. The material can be adjusted with reference to the general construction performance targets of shield wall grouting (consistency 8-12cm, fluidity 20-25cm, water bleeding rate <5%, setting time 12-18h), which can better adapt to different strata permeability and construction rhythm, reduce the risks of pipe blockage, grout leakage or insufficient filling, and provide more reliable material and process guarantee for flexible grouting that takes into account both seismic resistance and energy dissipation and watertight seepage prevention under complex working conditions. Detailed Implementation

[0070] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0071] Any preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0072] The numerous details listed in this specification are merely intended to provide the reader with a thorough understanding of one or more aspects of the invention, which can be achieved even without these specific details. Furthermore, the performance test data in the following embodiments are exemplary data (used to illustrate the relationship between proportions and performance, and the technical effects achievable by the invention), and are not the only experimental results for any specific project or sample; in actual engineering applications, these results can be verified and corrected based on raw material batches, ambient temperature and humidity, stirring and pumping conditions, etc.

[0073] As described in the background section, traditional cement-based synchronous grouting materials have high elastic modulus after curing, are generally stiff and brittle. Under conditions of seismic action, differential settlement, or deformation of soft and hard strata, they are prone to stress concentration and inducing cracking and leakage. Furthermore, the grout is prone to segregation and bleeding within the construction window, making it difficult to balance stability and workability, and resulting in insufficient on-site reproducibility.

[0074] To address the aforementioned issues, this invention provides a flexible seepage-proof shield tunnel synchronous grouting material, which is an emulsified asphalt-cement composite system, comprising at least emulsified asphalt, cement, fine aggregate, water-reducing agent, and sodium-based bentonite. Furthermore, a cellulose stabilizer is introduced to enhance the stability of the emulsified phase and interfacial compatibility. Preferably, an asphalt phase-modifying toughening component is also introduced to construct a multiphase energy-dissipating structure. If necessary, a self-healing component and / or tensile-crack-resistant fiber are introduced to improve the self-sealing of microcracks and long-term watertightness. This allows the grouting layer to meet support requirements while possessing a lower modulus and stronger energy-dissipating buffering capacity, achieving synergistic effects of earthquake resistance and seepage prevention.

[0075] This invention relates to a flexible seepage-proof shield tunnel synchronous grouting material, its preparation method, and its application. The material uses emulsified asphalt as the continuous phase, compounded with cement, fine aggregate, water-reducing agent, and special clay (bentonite). The cement / emulsified asphalt ratio is 35%–60%, fine aggregate / emulsified asphalt ratio is 50%, water-reducing agent / cement ratio is 0.5%, and bentonite / emulsified asphalt ratio is 4.0%. Cellulose stabilizers are further introduced, and modified emulsified asphalt is used when necessary to improve the stability and interfacial compatibility of the emulsified phase. It can also be compounded with asphalt phase modification and toughening components to construct a multiphase energy-dissipating structure. Due to the continuous film-forming and waterproof sealing properties of the asphalt phase itself, this material, after being injected into the shield tail void, can achieve continuous and dense backfilling and naturally form an excellent watertight barrier. Simultaneously, the stabilizing components and dispersion process inhibit flocculation, segregation, and bleeding, ensuring that the grout has good pumpability, diffusivity, and a suitable setting time within the construction window. After the grout solidifies, it forms a composite grouting layer with moderate strength, low elastic modulus and viscoelastic energy dissipation characteristics. It can effectively absorb and dissipate energy under earthquake or uneven deformation conditions, provide buffer for the tunnel segments and reduce stress concentration, thereby achieving a synergistic improvement in shock absorption, crack resistance and long-term seepage prevention.

[0076] In this process, emulsified asphalt exists in the slurry as micro-emulsified droplets. After the slurry solidifies, the emulsified asphalt phase can form multi-scale flexible energy-dissipating units. Combined with the skeletal load-bearing effect of the cementitious phase, it results in a hardened body with moderate strength, low elastic modulus, and viscoelastic energy-dissipating characteristics. Cellulose stabilizers and bentonite work together to significantly inhibit flocculation, segregation, and bleeding, and improve filling density. Toughening components can further improve toughness and crack resistance and energy dissipation capacity. Self-healing components and tensile crack-resistant fibers can reduce the risk of crack penetration and enhance the long-term reliability of the watertight barrier, thereby providing buffer energy dissipation for the tunnel segments and reducing leakage risks under seismic and uneven deformation conditions.

[0077] To facilitate the description of proportion control, the following parameters are used in this invention: C / A represents the mass ratio of cement to emulsified asphalt (%); F / A represents the mass ratio of fine aggregate to emulsified asphalt (%); R / C represents the mass ratio of water-reducing agent to cement (%); B / A represents the mass ratio of bentonite to emulsified asphalt (%); S / A represents the mass ratio of cellulose stabilizer to emulsified asphalt (%); T / A represents the mass ratio of asphalt phase modification toughening component to emulsified asphalt (%); H / C represents the mass ratio of self-healing component to cement (%); P / C represents the mass ratio of tensile crack-resistant fiber to cement (%). The following examples all use 2000 g of emulsified asphalt as a baseline, and achieve a synergistic match of workability, stability, strength, flexibility, energy dissipation, and watertightness by adjusting C / A and compounding S / A, T / A, H / C, and P / C.

[0078] The emulsified asphalt (unmodified emulsified asphalt) is preferably cationic slow-cracking and fast-setting emulsified asphalt; the cement is preferably PO42.5 ordinary Portland cement; the fine aggregate is preferably 60-110 mesh natural quartz sand; the water-reducing agent is preferably naphthalene-based water-reducing agent; the bentonite is preferably sodium-based bentonite; the cellulose stabilizer is preferably carboxymethyl cellulose and / or cellulose ether; the asphalt phase modification and toughening component is preferably SBS and / or rubber particles; the self-healing component is preferably a microcapsule-type self-healing agent; and the tensile crack-resistant fiber is preferably PE fiber.

[0079] To make the objectives, technical solutions, and advantages of this invention clearer, the following description, in conjunction with preferred embodiments, further illustrates the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, all of which should fall within the protection scope of this invention. The details listed in the specification are for facilitating understanding of one or more aspects of the invention and are not intended to limit the invention. Furthermore, the performance test data in the following embodiments are exemplary data, used to illustrate the variation patterns between proportions, processes, and performance, as well as the technical effects achievable by this invention; in actual engineering applications, these can be verified and corrected based on raw material batches, ambient temperature and humidity, stirring and pumping conditions, etc.

[0080] As described in the background section, traditional cement-based synchronous grouting materials have high elastic modulus after curing, are generally stiff and brittle. Under conditions of seismic action, differential settlement, or deformation of soft and hard strata, they are prone to stress concentration, which can induce cracking and interface debonding, resulting in insufficient seismic energy dissipation. At the same time, the grout is prone to segregation and bleeding within the construction window, making it difficult to balance stability and workability. The mixing and pumping process is sensitive to the process, and its on-site reproducibility is insufficient.

[0081] To address the aforementioned issues, this invention provides a flexible, seepage-proof shield tunnel synchronous grouting material, which is an emulsified asphalt-cement composite system, comprising at least emulsified asphalt, cement, fine aggregate, water-reducing agent, and sodium-based bentonite. Furthermore, a cellulose-based stabilizer is introduced to enhance the stability and interfacial compatibility of the emulsified phase. Preferably, asphalt phase modification and toughening components are also introduced to construct a multiphase viscoelastic energy-dissipating structure. If necessary, self-healing components and / or tensile-resistant fibers are introduced to improve crack resistance and microcrack self-sealing capability. It should be noted that the emulsified asphalt, as a continuous phase, inherently possesses waterproof film-forming and pore-sealing properties, forming a continuous watertight structure within the tail gap. This invention, through stabilization control and the synergistic effect of toughening / self-healing, enables the grouting layer to meet support requirements while possessing a lower modulus and stronger energy-dissipating buffering capacity, further improving long-term watertight reliability and achieving a synergistic improvement in seismic energy dissipation and natural seepage prevention.

[0082] The material composition of each embodiment and comparative example is shown in Tables 1 and 2.

[0083] Unless otherwise specified, all raw materials used in the following embodiments of the present invention were purchased commercially. The unmodified emulsified asphalt was BC-1 cationic slow-cracking fast-setting emulsified asphalt purchased from Xinxiang Tantou Road & Bridge Engineering Co., Ltd., with a solid content of 58.7%; the base asphalt for the modified emulsified asphalt was petroleum asphalt AC90 purchased from Fenyangtang (Shanghai) Industrial Co., Ltd.; and the cement was PO42.5 ordinary Portland cement purchased from Conch Cement Plant, with a specific surface area of ​​320 m². 2 / kg, 28-day compressive strength is 48MPa; fine aggregate is natural quartz sand purchased from Heyuan Wanchuan Quartz Development Co., Ltd., with a particle size of 60-110 mesh; water-reducing agent is naphthalene-based water-reducing agent purchased from Shanghai Chenqi Chemical Technology Co., Ltd., in brownish-yellow powder form; sodium-based bentonite is sodium-based bentonite purchased from Henan Xuanran Mineral Products Co., Ltd., with a particle size of 200-325 mesh, montmorillonite content of 60%, and density of 120g / cm³. 3 The red clay used was purchased from Sichuan Detai Industrial Co., Ltd. In this embodiment, sodium carboxymethyl cellulose (CMC) was specifically used as the cellulose stabilizer, purchased from Dongguan Ruiheng Mineral Products Co., Ltd., with a viscosity of 550 mPa·s, a degree of substitution of 0.9, and a density of 0.8 g / cm³. 3 In this embodiment, the asphalt phase modification and toughening component specifically uses SBS, purchased from Shenzhen Suyuan Industrial Co., Ltd. The self-healing component uses polyvinyl butyral (PVB) solution, purchased from Fenyangtang (Shanghai) Industrial Co., Ltd.; the tensile crack-resistant fiber uses PE fiber (ultra-high molecular weight polyethylene fiber), purchased from Shanghai Jinfujia New Materials Co., Ltd., with an elongation at break of 3.3%, a tensile strength of 3500 MPa, and a length of 9.00 mm.

[0084] Comparative Example 1 This comparative example provides a cement-based synchronous grouting material, the formulation of which is shown in Table 2. The preparation method of the cement-based synchronous grouting material includes the following steps: First, water and water-reducing agent are added to a mixer equipped with a dispersing rotor and stirred at a low speed of 500 rpm for 2 minutes to form a homogeneous liquid phase. Then, cement, fine aggregate (natural quartz sand), and bentonite are added and stirred at 1000 rpm for 5 minutes to obtain a cement-based synchronous grouting material. This material provides rapid early support, but after curing, it has a high modulus and is relatively brittle, making it prone to cracking and leakage under earthquakes or differential deformation.

[0085] Comparative Example 2 This comparative example provides a synchronous grouting material, the formulation of which is shown in Table 2. The preparation method of the synchronous grouting material includes the following steps: (1) Weigh out the unmodified emulsified asphalt, cement, fine aggregate, water-reducing agent and bentonite according to Table 2.

[0086] (2) Add the unmodified emulsified asphalt to a mixer with a dispersing rotor and stir at a low speed of 500 rpm for 1 min; after adding the water-reducing agent, continue stirring at 500 rpm for 2 min to ensure that the water-reducing agent is fully dispersed in the continuous phase of the emulsified asphalt.

[0087] (3) After pre-dry mixing cement and fine aggregate for 1 minute, add them in equal amounts to the continuous phase system obtained in step (2) in three batches. Stir at 500 rpm for 30 seconds after each addition. After the three additions are completed, switch to 1000 rpm for 2 minutes to obtain a uniform premixed slurry.

[0088] (4) Add bentonite to the premixed slurry obtained in step (3) and continue stirring at 1000 rpm for 5 min until the slurry is uniform and stable with no obvious agglomeration or segregation, thus obtaining the synchronous grouting material. This comparative example does not add cellulose stabilizers and is used to characterize the basic properties of the system without stable compatibility control.

[0089] Comparative Example 3 This comparative example provides a flexible seepage-proof shield tunnel synchronous grouting material, the formulation of which is shown in Table 2. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: The preparation method is the same as in Example 1, except that no bentonite is added in this comparative example; only a cellulose-based stabilizer is added. Due to the lack of the thickening and stabilizing effect of bentonite, the system is more prone to bleeding and insufficient structural recovery during standing or pumping.

[0090] Comparative Example 4 This comparative example provides a synchronous grouting material, the formulation of which is shown in Table 2. The preparation method of the synchronous grouting material includes the following steps: The preparation method is the same as in Example 1, except that the cement / emulsified asphalt mass ratio is increased to 70% in this comparative example to characterize the problem of increased system modulus, decreased flexibility and energy consumption capacity when the cement content is too high.

[0091] Comparative Example 5 This comparative example provides a synchronous grouting material, the formulation of which is shown in Table 2. The preparation method of the synchronous grouting material includes the following steps: (1) Weigh out the unmodified emulsified asphalt, cement, fine aggregate, water-reducing agent, bentonite and cellulose stabilizer according to Table 2.

[0092] (2) Add the unmodified emulsified asphalt to the mixer and mix at a low speed of 500 rpm for 1 min.

[0093] (3) After pre-dry mixing cement and fine aggregate for 1 minute, add them to emulsified asphalt in three equal portions, stirring at 500 rpm for 30 seconds after each addition; after the three additions are completed, add water-reducing agent and stir for 1 minute, then add cellulose stabilizer and stir for 1 minute.

[0094] (4) After stirring the system at 1000 rpm for 2 min, add bentonite and continue stirring at 1000 rpm for 5 min to obtain synchronous grouting material.

[0095] This comparative example uses a different key feeding sequence than that of the present invention to characterize the impact of an unreasonable feeding sequence on the system's dispersion uniformity and anti-segregation stability.

[0096] Example 1 This embodiment provides a flexible seepage-proof shield tunnel synchronous grouting material, the formula of which is shown in Table 1. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: (1) Weigh out the unmodified emulsified asphalt, cement, fine aggregate, water-reducing agent, bentonite and cellulose stabilizer according to Table 1.

[0097] (2) Add the unmodified emulsified asphalt to a mixer with a dispersing rotor and stir at a low speed of 500 rpm for 1 min; add the water-reducing agent by dripping and continue stirring at 500 rpm for 2 min; then add the cellulose stabilizer and continue stirring at 500 rpm for 2 min to form a uniform and stable continuous phase system.

[0098] (3) After pre-dry mixing cement and fine aggregate for 1 minute, add them in equal amounts to the continuous phase system obtained in step (2) in three batches. After each addition, stir at 500 rpm for 30 seconds. After the three additions are completed, switch to 1000 rpm for 2 minutes to obtain a uniform premixed slurry.

[0099] (4) Add bentonite to the premixed slurry obtained in step (3) and continue stirring at 1000 rpm for 5 min until the slurry is uniform and stable, without obvious agglomeration and segregation, to obtain synchronous grouting material.

[0100] Example 2 This embodiment provides a flexible seepage-proof shield tunnel synchronous grouting material, the formula of which is shown in Table 1. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: The preparation method is the same as in Example 1, except that in step (4), red clay and bentonite are pre-dry mixed for 1 min and then added together to the premixed slurry, and stirred at 1000 rpm for 5 min. The introduction of red clay can further regulate the thixotropy, anti-bleeding stability and structural recovery ability under pump shear of the system.

[0101] Example 3 This embodiment provides a flexible seepage-proof shield tunnel synchronous grouting material, the formula of which is shown in Table 1. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: The preparation method is the same as in Example 1, except that in step (3), cement, fine aggregate and self-healing component are pre-mixed dry for 1 minute and then added to the continuous phase system obtained in step (2) in three equal amounts. The self-healing component can self-seal microcracks during service life, thereby improving long-term water tightness.

[0102] Example 4 This embodiment provides a flexible seepage-proof shield tunnel synchronous grouting material, the formula of which is shown in Table 1. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: The preparation method is the same as in Example 1, except that after the continuous phase system is prepared in step (2), the tensile crack-resistant fiber is slowly added in small amounts and evenly, and stirred at 500 rpm for 2 min to ensure that the fiber is fully wetted and there is no visible agglomeration. Then, the powder is added in step (3). The tensile crack-resistant fiber can inhibit crack propagation and penetration, further improving crack resistance and long-term watertight reliability.

[0103] Example 5 This embodiment provides a flexible seepage-proof shield tunnel synchronous grouting material, the formula of which is shown in Table 1. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: The preparation method is the same as in Example 1, except that in step (2), after adding the cellulose stabilizer and stirring evenly, the asphalt phase modified toughening component is added, and stirring is continued at 500 rpm for 2 minutes to ensure that the toughening component is evenly dispersed in the emulsified asphalt continuous phase, forming a continuous phase system containing stabilizer and toughening component. The toughening component can further improve the toughness and energy dissipation capacity of the hardened body, giving the grouting layer a better buffering effect under earthquakes or uneven deformation.

[0104] Example 6 This embodiment provides a flexible seepage-proof shield tunnel synchronous grouting material, the formula of which is shown in Table 1. The preparation method of the flexible seepage-proof shield tunnel synchronous grouting material includes the following steps: (1) Preparation of modified emulsified asphalt: First, a stable emulsion was prepared. Bentonite, emulsifier, and sodium carboxymethyl cellulose were weighed at a mass ratio of 15:4:1, including 42g of bentonite, 11.2g of emulsifier, and 2.8g of sodium carboxymethyl cellulose. 644g of water was added, and the mixture was stirred at 500rpm for 30min at 60℃ to obtain 700g of stable emulsion. 1300g of base asphalt was heated to 145℃ and held for 30min, and then subjected to secondary emulsification and shearing compounding with the stabilized emulsion at a mass ratio of 65:35 to obtain 2000g of modified emulsified asphalt.

[0105] (2) Weigh the modified emulsified asphalt, cement, fine aggregate and water-reducing agent obtained in step (1) according to Table 1, and add 38g of bentonite and 3.2g of cellulose stabilizer to make the total amount of bentonite in the final system 80g and the total amount of cellulose stabilizer 6g.

[0106] (3) Add the modified emulsified asphalt to the mixer and stir at a low speed of 500 rpm for 1 min; add the water-reducing agent by dripping and continue stirring at 500 rpm for 2 min; then add the added cellulose stabilizer and continue stirring at 500 rpm for 2 min to form a uniform and stable continuous phase system.

[0107] (4) After pre-dry mixing cement and fine aggregate for 1 minute, add them in equal amounts to the continuous phase system obtained in step (3) in three batches. Stir at 500 rpm for 30 seconds after each addition. After the three additions are completed, switch to 1000 rpm for 2 minutes to obtain a uniform premixed slurry.

[0108] (5) Add the added bentonite to the premixed slurry obtained in step (4) and continue stirring at 1000 rpm for 5 min until the slurry is uniform and stable, without obvious agglomeration and segregation, to obtain the synchronous grouting material.

[0109] The introduction of modified emulsified asphalt can further improve the continuous phase's resistance to demulsification, segregation, and batch stability under high powder impact and pumping shear conditions.

[0110] The formulations of the examples and comparative examples are based on a mass of 2000g of emulsified asphalt. The formulations of the examples are shown in Table 1, and the formulations of the comparative examples are shown in Table 2.

[0111] Table 1. Formulation of synchronous grouting materials in the examples

[0112] Table 2 Comparative Example Synchronous Grouting Material Formulation

[0113] In Table 1, “2000g of emulsified asphalt” in Example 6 is modified emulsified asphalt.

[0114] In Table 1, the total amount of bentonite (80g) and cellulose stabilizer (6g) in Example 6 includes the sum of the amount introduced during the preparation stage of the modified emulsified asphalt and the amount added subsequently. Specifically, 42g of bentonite and 2.8g of sodium carboxymethyl cellulose were introduced during the preparation stage of the modified emulsified asphalt, and 38g of bentonite and 3.2g of sodium carboxymethyl cellulose were added during subsequent mixing.

[0115] Comparative Example 1 is a typical cement-based synchronous grouting material, used to demonstrate the problems of high stiffness, brittleness, and insufficient seismic energy dissipation after curing in traditional systems; Comparative Example 2 is used to characterize the basic properties of the emulsified asphalt-cement composite system without the introduction of cellulose-based stabilizers; Comparative Example 3 is used to characterize the problems of insufficient system stability and bleeding control without the addition of bentonite; Comparative Example 4 is used to characterize the problems of increased modulus and decreased deformation coordination of the hardened body when the cement / emulsified asphalt ratio deviates from the preferred range; Comparative Example 5 is used to characterize the impact of unreasonable key addition sequence on the uniformity and stability of the system. Examples 1 to 6 all contain cellulose-based stabilizers, used to characterize the effects of the basic formulation, red clay, self-healing components, tensile crack-resistant fibers, asphalt phase modified toughening components, and modified emulsified asphalt on material properties, respectively.

[0116] Application Examples Synchronous grouting process: The grout (synchronous grouting material) prepared in the above embodiments and comparative examples is pumped to the tail gap of the shield through the shield synchronous grouting pump for grouting; if necessary, a secondary grouting process can be combined to improve the filling density of the tail gap.

[0117] To verify the workability, setting and hardening characteristics, mechanical properties, and impermeability of the material of this invention, the following methods were used for testing: Flowability was determined according to GB / T 2419-2005, "Method for Determination of Flowability of Cement Mortar," using a flow table to record the expansion diameter in mm; Bleeding rate was determined according to Appendix A of T / DGGC 27—2024 / T / BAPE3—2024, "Technical Standard for Synchronous Grouting in Shield Tunneling," using the static setting method with a 250mL graduated cylinder, in mm; Setting time was determined according to GB / T 1346-2024, "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement," using a Vicat apparatus, recording the initial and final setting times in hours; Compressive strength was determined according to JGJ / T 70-2009, "Standard for Test Methods of Basic Performance of Building Mortar," using 70.7mm×70.7mm×70.7mm cubic specimens, measured for 28 hours. The compressive strength (d) is measured in MPa. The splitting tensile strength was determined according to GB / T 50081-2019, "Standard for Test Methods of Physical and Mechanical Properties of Concrete," using 100mm×100mm×100mm cubic specimens. The 28-day splitting tensile strength was measured in MPa. The water permeability coefficient was measured according to the water permeability test method in GB / T 50082-2024, "Standard for Test Methods of Long-Term Performance and Durability of Concrete," and the permeability coefficient k was measured in cm·s. -1 The smaller the value, the better the seepage prevention performance; the dynamic modulus E* is tested using an electro-hydraulic servo universal testing machine or a dynamic mechanical testing system under sinusoidal loading conditions of 20±2℃ and 10Hz, and the unit is MPa. The curing conditions are 20±2℃ and relative humidity not less than 90%.

[0118] Example test data for the embodiments are shown in Table 3, and example test data for the comparative examples are shown in Table 4.

[0119] Table 3 Performance test data of the embodiments

[0120] Table 4 Performance test data of the comparative example

[0121] As shown in Tables 3 and 4, under the premise of meeting the flow diffusion performance and setting time window required for synchronous grouting construction, Comparative Example 2 shows that the emulsified asphalt-cement composite system itself has certain low modulus and seepage prevention potential. However, in the absence of cellulose stabilizers, the system's anti-segregation stability and batch consistency are insufficient. In Example 1, after introducing cellulose stabilizers, the slurry bleeding rate was significantly reduced, indicating that cellulose stabilizers, as an essential technical feature, can effectively enhance the stability of the emulsion phase and interfacial compatibility, thereby improving low bleeding and tail gap filling density. Compared with Example 1, Comparative Example 3 shows that in the absence of bentonite, the system's thixotropy, structural recovery ability, and anti-bleeding stability decreased, indicating that bentonite has an irreplaceable thickening and stabilizing effect in this invention. Compared with Example 1, Comparative Example 4 shows that when the cement / emulsified asphalt ratio deviates from the preferred range, the dynamic modulus of the hardened body significantly increases, while the flexibility and energy dissipation capacity decrease, which is not conducive to the deformation coordination of shield tunnels under seismic or uneven deformation conditions. Comparative Example 5, compared with Example 1, shows that the key feeding sequence has a significant impact on the uniformity, stability and final performance of the system. The process sequence of "continuous phase pre-dispersion - powder added in three equal amounts in three batches - special soil stabilization treatment" described in this invention is more conducive to obtaining uniform and stable synchronous grouting materials.

[0122] Example 2 shows that the introduction of red clay can further improve the system's thixotropy, anti-bleeding stability, and structural recovery capacity under pumping shear. Example 3 shows that the self-healing component can further improve the self-sealing ability of microcracks in the hardened body and its long-term watertight stability. Example 4 shows that the introduction of tensile crack-resistant fibers helps to inhibit crack propagation and penetration, thereby improving crack toughness and seepage prevention reliability. Example 5 shows that the asphalt phase modified toughening component can further reduce the dynamic modulus of the hardened body and improve its energy dissipation capacity, giving the grouting layer a better buffering effect under earthquakes and differential deformation. Example 6 shows that modified emulsified asphalt can further improve the stability of the continuous phase under high powder impact and pumping shear conditions, thereby improving grout homogeneity, low bleeding performance, and long-term watertightness.

[0123] In summary, this invention, through the system design of emulsified asphalt-cement composite + necessary stable phase control with cellulose stabilizers + bentonite stabilization treatment + optional red clay / self-healing components / tensile crack-resistant fibers / asphalt phase modified toughening components / modified emulsified asphalt, can maintain good pumpability and low bleeding while achieving moderate strength, low modulus, and higher energy consumption in the hardened body. Furthermore, relying on the natural impermeability of the asphalt continuous phase, it forms a continuous, dense, and long-term reliable watertight barrier, thereby better meeting the engineering needs of shield tunnels under complex conditions such as earthquakes, uneven deformation, and long-term leakage control.

[0124] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A flexible seepage-proof shield tunnel synchronous grouting material, characterized in that, The synchronous grouting material includes the following components: emulsified asphalt, cement, fine aggregate, water-reducing agent, special soil, and cellulose stabilizer; The special soil includes bentonite; The components of the synchronous grouting material satisfy the following mass ratio relationship: Cement / Emulsified Asphalt = 35%–60% Fine aggregate / emulsified asphalt = 40~60%, Water-reducing agent / cement ratio: 0.2~1.0% Bentonite / emulsified bitumen = 2~6%; Cellulose stabilizer / emulsified asphalt = 0.05%~2.0%.

2. The flexible seepage-proof shield tunnel synchronous grouting material according to claim 1, characterized in that, The synchronous grouting material uses emulsified asphalt as the continuous phase and cement as the cementitious phase; The emulsified asphalt is either unmodified emulsified asphalt or modified emulsified asphalt. The special soil also includes red clay; by mass ratio, red clay / emulsified asphalt = 1~5%; The cement is PO42.5 ordinary Portland cement; The fine aggregate is natural quartz sand with a mesh size of 60-110. The water-reducing agent is one or more of the following: naphthalene-based water-reducing agent, polycarboxylate-based water-reducing agent, melamine-based water-reducing agent, and aminosulfonic acid-based water-reducing agent. The cellulose stabilizers include carboxymethyl cellulose and / or cellulose ethers.

3. The flexible seepage-proof shield tunnel synchronous grouting material according to claim 2, characterized in that, The unmodified emulsified asphalt is one or more of anionic emulsified asphalt, cationic emulsified asphalt, and nonionic emulsified asphalt; The modified emulsified asphalt is obtained by secondary emulsification and shearing compounding of thermally modified base asphalt and stable emulsion. The stabilized emulsion includes special soil, emulsifier, and cellulose stabilizer; In the stabilized emulsion, the mass ratio of special soil, emulsifier and cellulose stabilizer is (10-20):(2-6):1; The mass ratio of the thermally modified matrix asphalt to the stabilized emulsion is (60-70):(40-30). The thermally modified base asphalt is petroleum asphalt AC90.

4. The flexible seepage-proof shield tunnel synchronous grouting material according to claim 1, characterized in that, The synchronous grouting material also includes asphalt phase modification and toughening components; The asphalt phase modification toughening component, based on emulsified asphalt, is added at a rate of 1% to 9% by mass. The asphalt phase modified toughening component is selected from one or more of SBS, rubber particles, polyether polyols and nano-rubber powders.

5. The flexible seepage-proof shield tunnel synchronous grouting material according to claim 1, characterized in that, The synchronous grouting material also includes tensile crack-resistant fibers; The tensile crack-resistant fiber, based on cement content, is added at a rate of 0.05% to 0.5% by mass. The tensile-crack-resistant fiber is one or more of polypropylene fiber, PE fiber, polyvinyl alcohol fiber, and alkali-resistant glass fiber.

6. The flexible seepage-proof shield tunnel synchronous grouting material according to claim 1, characterized in that, The synchronous grouting material also includes a self-healing component; The self-healing component, based on cement by mass fraction, is added at a rate of 1% to 10%. The self-healing component is selected from one or more of hollow glass fibers, acetal polymer solutions, and pozzolanic silicate cement.

7. A method for preparing a flexible seepage-proof shield tunnel synchronous grouting material as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Weigh the components of the synchronous grouting material according to the mixing ratio; (2) Add the water-reducing agent to the emulsified asphalt, stir and disperse it, then add the cellulose stabilizer and continue stirring to obtain a continuous phase system; (3) After the cement and fine aggregate are pre-dry mixed evenly, they are added in batches to the continuous phase system obtained in step (2). First, stir at low speed, then switch to medium and high speed to obtain a mixed system. (4) Add special soil to the mixture obtained in step (3) and continue stirring to obtain slurry, which is the synchronous grouting material.

8. The preparation method according to claim 7, characterized in that, In step (2), the water-reducing agent is added by dripping. In step (3), the low-speed stirring rate is 300-600 rpm, and the medium-high speed stirring rate is 800-1200 rpm; In step (3), the medium-high speed stirring time is not less than 2 minutes; In step (3), the total time for low-speed stirring and medium-high-speed stirring is 2 to 10 minutes; In step (4), the continuous stirring time is 3 to 15 minutes; When the synchronous grouting material includes an asphalt phase modified toughening component, the asphalt phase modified toughening component is premixed with the emulsified asphalt before the water-reducing agent is added to the emulsified asphalt. When the synchronous grouting material includes tensile crack-resistant fibers, the tensile crack-resistant fibers are introduced in step (2): when the emulsified asphalt continuous phase is in a low-speed stirring state, the tensile crack-resistant fibers are slowly added in small amounts and evenly sprinkled in, and the stirring is continued until the fibers are fully wetted and there are no visible fiber agglomerations. Then, the cement and fine aggregates in step (3) are pre-dry mixed evenly and added in batches until there are no visible fiber agglomerations and no floating fiber bundles in the grout. The dispersion is completed. When the synchronous grouting material includes a self-healing component, the self-healing component, cement, and fine aggregate are pre-dry mixed evenly.

9. The application of a flexible seepage-proof shield tunnel synchronous grouting material as described in any one of claims 1-6, characterized in that, The synchronous grouting material is used for synchronous grouting backfilling of the shield tail voids on the outside of the shield tunnel segments; The application includes the following process: Synchronous grouting material is used for synchronous grouting backfilling of the shield tail void outside the shield tunnel segment. After being injected into the shield tail void outside the shield tunnel segment, it forms a continuous and dense filling layer and a watertight barrier is formed by the asphalt phase. After hardening, it constitutes a composite grouting layer.

10. The application according to claim 9, characterized in that, Before using synchronous grouting material for synchronous grouting backfilling of the shield tail gap outside the shield tunnel segment, the grout is depressurized, degassed, and stabilized before being discharged.

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