Mixed type shield synchronous grouting material and grouting process

Abstract

The invention provides a mixed type shield synchronous grouting material and a grouting process, and relates to the technical field of building materials, the grouting material is composed of fast hydration Portland cement, activated aluminosilicate minerals, nanometer silicon powder, bentonite, a reversible thixotropic polymer, a delayed hydration agent, coated calcium aluminate fast setting powder and a coated silicate gel precursor. The early-stage reaction is inhibited by delaying hydration, and a controllable solidification sequence of slurry from a flowable stage, a rearrangement structure stage to a rapid solidification stage is realized by breaking a membrane under the action of temperature or pressure gradient. In the process, by monitoring the conductivity, the concentration of Ca < 2 + > / Mg < 2 + > and the temperature in real time, the adding amount of an additive and grouting parameters are automatically adjusted, so that the stable diffusivity of the material is kept and the curing speed is accelerated under different stratum conditions. The solidified body forms a C-S-H, C-A-S-H and N-A-S-H gel interpenetrating network, the permeability coefficient is low, the water dispersion resistance is high, and the shield grouting quality and the tunnel structure safety can be remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a hybrid shield tunnel synchronous grouting material and grouting process. Background Technology

[0002] In shield tunnel construction, the gap between the cutterhead and the tunnel segments needs to be filled promptly through synchronous grouting to maintain ground stability, control surface settlement, and ensure the segment orientation. However, traditional cement-based or cement-bentonite synchronous grouting materials generally suffer from insufficient diffusivity, susceptibility to groundwater runoff, low early strength, and uncontrollable solidification. In water-rich sandy environments, the grout often leaks due to ion exchange and high permeability pathways; in cohesive soils, it is prone to uneven filling or voids due to premature setting. Furthermore, traditional grouting systems typically cannot automatically adjust the solidification reaction based on changes in formation ion strength, pressure gradient, and temperature, resulting in grouting effectiveness dependent on manual experience and poor stability. Current technology has not yet provided a hybrid grouting material and process that can automatically adjust the solidification process under different geological conditions, form a dense and stable solidified body, and achieve intelligent control. Summary of the Invention

[0003] Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a hybrid shield tunnel synchronous grouting material and grouting process, which solves the problems of existing technologies.

[0005] Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a hybrid shield tunneling synchronous grouting material, wherein the grouting material comprises:

[0007] 15-25 parts of fast-hydrating silicate cement;

[0008] 8–15 parts activated aluminosilicate minerals;

[0009] 1-3 parts nano-silicon powder;

[0010] 4 to 7 parts bentonite;

[0011] 0.2–0.5 parts of reversible thixotropic polymer;

[0012] 0.05–0.10 parts of delayed hydration agent;

[0013] 1-3 parts of coated calcium aluminate quick-setting powder;

[0014] 0.5–1 part of coated silicate gel precursor;

[0015] Delayed hydration agents inhibit the hydration of cement and aluminosilicate minerals within 0 to 20 minutes. Coated calcium aluminate fast-setting powder and coated silicate precursors enter the film-breaking stage within 20 to 60 minutes and produce a rapid gel reaction, so that the slurry forms a controllable solidification sequence consisting of "flowable stage - rearranged structure stage - rapid solidification stage".

[0016] Preferably, the coating thickness of the coated calcium aluminate rapid-setting powder is 2-20 μm, and the material is selected from polyvinyl alcohol, aliphatic wax or thermoplastic acrylic emulsion; by adjusting the coating thickness and melting point, the film breaking time of the coated particles is controlled by the coupling of three factors: temperature, pressure and pH, thereby achieving an adjustable film breaking window of 20-60 minutes.

[0017] Preferably, the activated aluminosilicate minerals inhibit the early-stage reaction under the action of a delayed hydration agent. When the coated silicate precursor breaks down, the Si-O released by the precursor... - and Al-O - Upon entering the solution, it induces the formation of an inorganic gel network dominated by CASH / NASH, which interpenetrates with the CSH network generated by the later silicate hydration, forming a composite microstructure with "early water-resistant properties + later load-bearing capacity".

[0018] Preferably, the reversible thixotropic polymer is used when the shear rate changes from 0 s⁻¹. -1 Increase to 100s -1 When shearing is applied, the viscosity decreases by 30%–60%, but recovers to 80%–95% of its original viscosity within 5 minutes. Furthermore, its chain segments contain weakly coordinating Ca. 2+ The side bases enable it to form an enhanced temporary network in water-rich, high-ion-strength formations, thereby improving the grout's resistance to water dispersion.

[0019] Preferably, the ion-responsive polymer is reacted with Ca. 2+ / Mg 2+ The coordination constant is in 10 2 ~10 3 In the L / mol range, when Ca in the aquifer water 2+ When the concentration is greater than 50 mg / L, the initial setting time of the grout is shortened by 20% to 40%. 2+ When the concentration is below 10 mg / L, the initial setting time is extended by 10% to 30%, thereby achieving automatic adjustment of the setting rate based on the formation ion strength.

[0020] Preferably, the microstructure of the grouting material satisfies the following characteristics:

[0021] The pore size of the gel network is mainly distributed in the range of 10–500 nm;

[0022] The ratio of CASH phase to CSH phase is between 1:1 and 1:3;

[0023] Nano-silica powder forms uniformly dispersed secondary cementing points in the gel phase, enhancing the microstructure density of the hardened body, with a permeability coefficient K≤1×10⁻⁶. -11 m / s

[0024] Preferably, the grouting process includes the following steps:

[0025] Sp1, real-time measurement of formation water conductivity and Ca 2+ / Mg 2+ Concentration and temperature;

[0026] Sp2. The dosage of delayed hydration agent and ion-responsive polymer is automatically adjusted based on conductivity and ion concentration.

[0027] Sp3. Real-time adjustment of grouting speed to control the grouting material to maintain a low viscosity diffusion stage in the shield tail gap for 20 to 60 minutes;

[0028] Sp4 triggers a rapid gelation reaction between calcium aluminate quick-setting powder and silicate precursor by coating particles to break the membrane, causing the slurry to gradually harden from the tail of the shield to the outer edge to form a continuous and dense solid.

[0029] Preferably, the membrane rupture of the coated particles is triggered by the following two conditions:

[0030] A. When the internal temperature of the solidified body rises above 25-35°C, the coating softens and ruptures.

[0031] B. When the slurry pressure gradient is greater than 0.05-0.15 MPa, the coating stress ruptures.

[0032] The system monitors the time of film rupture in real time through temperature and pressure sensors to achieve controllability of the solidification curve.

[0033] Preferably, the real-time controlled grouting speed is in the range of 20-80 L / min, so that the grout forms a diffusion front length of 2-6 cm in the shield tail gap, ensuring that the rheological network dominated by the thixotropic polymer is established first, and then the inorganic gel network solidifies sequentially behind the diffusion front, thereby forming a solidified body with gradient density.

[0034] Preferably, the hardware components of the grouting process include:

[0035] An ion monitoring module is used to measure Ca in the grouting environment in real time. 2+ / Mg 2+ concentration;

[0036] Grouting pump speed and pressure control module;

[0037] The membrane rupture process monitoring module includes temperature and pressure sensors;

[0038] The data processing controller is used to adjust the dosage ratio of delayed hydration agent, ion-responsive polymer and water based on monitoring data, and to control the grouting speed and pressure.

[0039] The controller executes a preset "solidification program curve" to enable the grouting material to achieve a controllable solidification process under the on-site geological conditions.

[0040] Beneficial effects

[0041] This invention provides a hybrid shield tunneling synchronous grouting material and grouting process. It has the following beneficial effects:

[0042] 1. This invention utilizes the synergistic effect of delayed hydration agents, reversible thixotropic polymers, coated calcium aluminate fast-setting powder, and coated silicate gel precursors to automatically transition the grouting material in a "flowable-rearrangeable-rapid solidification" sequence, adapting to the diffusion and solidification requirements of different strata without manual adjustment. The system can adjust the solidification process in real time based on stratum ionic strength, temperature, and pressure gradients, maintaining stable grouting quality under varying permeability conditions, such as water-rich sand layers and soft plastic clay layers, significantly improving the adaptability and controllability of shield tunneling construction.

[0043] 2. After curing, the material of this invention forms an interpenetrating network structure composed of CSH, CASH, NASH gels and nano-silicon secondary binders. The gel pore size is mainly distributed in the range of 10–500 nm, and the permeability coefficient can be as low as 1 × 10⁻⁶. -11 m / s. Compared with traditional cement-based grouting materials, this invention has higher resistance to water diffusion in high-permeability formations and better diffusion and filling effects in low-permeability viscous formations. It can form a continuous and dense solidified body, effectively reducing the risks of shield tail leakage, segment attitude drift and void formation.

[0044] 3. This invention constructs an automated grouting system combining ion monitoring, membrane rupture monitoring, and pump speed and pressure control, which can acquire Ca in real time. 2+ / Mg 2+ Information such as concentration, conductivity, temperature, and pressure gradient is collected and processed by a controller to execute a preset solidification program curve, enabling precise control of the grout's diffusion length, rheological properties, film breaking time, and curing process. This system effectively avoids problems such as premature solidification, excessive diffusion, or insufficient consolidation, ensuring the stability of the grout layer and the continuity of construction, thereby improving shield tunneling efficiency and construction safety. Attached Figure Description

[0045] Figure 1 This is a flowchart of the hybrid shield tunnel synchronous grouting process of the present invention;

[0046] Figure 2This is a schematic diagram of the hybrid shield tunnel synchronous grouting system of the present invention;

[0047] Figure 3 This is a diagram showing the overall microstructure of the present invention;

[0048] Figure 4 This is a microstructure diagram of Embodiment 2 of the present invention;

[0049] Figure 5 This is a microstructure diagram of Embodiment 3 of the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific Implementation Example 1:

[0052] like Figures 1 to 3 As shown, a hybrid shield tunneling synchronous grouting material comprises 15-25 parts rapid-hydrating silicate cement, 8-15 parts activated aluminosilicate minerals, 1-3 parts nano-silica powder, 4-7 parts bentonite, 0.2-0.5 parts reversible thixotropic polymer, 0.05-0.10 parts delayed hydration agent, 1-3 parts coated calcium aluminate rapid-setting powder, and 0.5-1 part coated silicate gel precursor, and may further incorporate 0.1-0.3 parts ion-responsive polymer. The rapid-hydrating silicate cement is preferably rapid-hardening silicate cement or sulfoaluminate cement, with a fineness controlled within a specific surface area of ​​400-600 square meters per kilogram, ensuring rapid formation of CSH gel during the later hydration stage, providing medium- and long-term compressive strength and dimensional stability for the consolidated body. Activated aluminosilicate minerals can be selected from metakaolin, oligomer precursors, or highly active fly ash. The particle size is preferably such that over 90% of the particles are less than 20 micrometers in diameter. Through alkali activation and the participation of calcium ions, an inorganic gel network mainly composed of CASH and NASH gels is formed, playing a dual role in the system as early-stage water dispersion resistance and mid-stage load-bearing framework. Nano-silica powder with a particle size preferably between 20 and 100 nanometers is uniformly dispersed in the slurry in powder or silica sol form. It provides numerous nucleation sites during the hydration process of cement and aluminosilicate minerals, promoting secondary hydration and secondary cementation. This concentrates the pore size distribution of the cementitious system within the 10-100 nanometer range, improving the overall microstructure's density and impermeability.

[0053] The bentonite used is sodium-based or modified calcium-based bentonite, with a swelling index preferably greater than or equal to 15 ml / 2g. Through the water absorption and swelling characteristics of its layered mineral structure and the bridging effect of its plate-like particles, it increases the yield stress and static viscosity of the grout, significantly reducing bleeding rate and segregation tendency, and forms a multi-level physical network with the reversible thixotropic polymer. The reversible thixotropic polymer is preferably a water-soluble polymer containing carboxyl or amide groups, such as partially hydrolyzed polyacrylamide or acrylic acid-acrylamide copolymer. The polymer's viscosity decreases by 30 to 60 percentage points when the shear rate increases from zero per second to one hundred per second, and recovers to 80% to 95% of its original viscosity within five minutes after shear is removed. Side groups that can weakly coordinate with calcium ions are introduced into the chain segment structure, enabling the polymer to form a reinforced temporary network through ionic cross-linking in water-rich, high-ionic-strength formations. This significantly improves the grout's resistance to water dispersion and loss near the shield tail gap and the outer edge of the tunnel segments. The delayed hydration agent is an organic retarder such as citrate, tartrate or gluconate. It forms a temporary passivation layer by complexing with calcium and aluminum ions on the surface of cement and activated aluminosilicate minerals. This inhibits the hydration reaction of cement and aluminosilicate minerals within a period of 0 to 20 minutes after grouting, keeping the grout system in a flowable stage dominated by the physical network of bentonite and thixotropic polymers, thus giving the grout sufficient pumpability and diffusivity.

[0054] The coating thickness of the coated calcium aluminate rapid-setting powder is two to twenty micrometers. The core is made of calcium aluminate clinker or high-alumina cement fine powder. The coating is formed by spray drying or dry spraying, using polyvinyl alcohol, aliphatic wax, or thermoplastic acrylic emulsion as the coating material. By adjusting the coating thickness and the melting point or glass transition temperature of the coating material, the film breaking time of the coated particles is designed to be simultaneously controlled by three factors: temperature, pressure, and slurry pH. This allows the calcium aluminate core to break down within a predetermined window in the second stage after grouting, within twenty to sixty minutes. Under localized temperature rise and pressure gradient conditions, it rapidly participates in the hydration reaction, generating calcium-aluminum hydrate gel and establishing an early rigid framework. The coated silicate gel precursor uses silica sol, metasilicate solution or low modulus water glass as the core, and forms a coating layer of two to twenty micrometers thick through polyvinyl alcohol, aliphatic wax or acrylic emulsion. The coating parameters are designed in coordination with the calcium aluminate particles. When the coating layer breaks down, the negatively charged silicon and aluminum oxide species released by the precursor enter the liquid phase and undergo a polymerization reaction with the silicon and aluminum components dissolved from the activated aluminosilicate minerals. This induces the formation of an inorganic gel network mainly composed of CASH gel and NASH gel. In a later stage, it interpenetrates and cross-links with the CSH gel network generated by the hydration of fast-hydrated silicate cement, forming a composite microstructure that has both early water dispersibility and mid-to-late-stage load-bearing capacity.

[0055] The ion-responsive polymer is designed as a water-soluble polymer containing coordinating groups such as carboxyl and sulfonic acid groups. Its coordination constant with calcium and magnesium ions is controlled in the range of 10^2 to 10^3 liters per mole. When the mass concentration of calcium ions in the formation water is greater than 50 mg / L, the polymer segments form more cross-linking points with calcium ions, increasing the apparent viscosity and local gelation degree of the system. The initial setting time of the grout is shortened by 20 to 40 percentage points compared with the baseline conditions, which is beneficial for the rapid formation of erosion-resistant structures in water-rich sand layers or limestone fractured strata. When the calcium ion concentration in the formation water is less than 10 mg / L and the conductivity is low, the degree of cross-linking of the polymer weakens, the system maintains a longer flowable time, and the initial setting time is extended by 10% to 30% compared with the baseline. This is beneficial for obtaining more sufficient diffusion and filling effects in soft plastic clay layers, thereby achieving automatic adjustment of the setting rate based on the formation ion strength.

[0056] The microstructure of the cured grouting material meets the following characteristics: the pore size of the gel network, measured by mercury indentation and nitrogen adsorption methods, is mainly distributed in the range of 10 to 500 nanometers, with a significant reduction in macroscopic continuous pores and a refinement and folding of the seepage path; the volume fraction ratio of the CASH gel phase to the CSH gel phase, characterized by X-ray diffraction and thermal analysis, is controlled in the range of 1:1 to 1:3, ensuring that the aluminosilicate gel skeleton and the silicate hydration skeleton work together to provide both good water erosion resistance and sufficient compressive modulus; under scanning electron microscopy, the nano-silica powder appears as spherical or clustered secondary cementing points uniformly dispersed in the gel phase, forming a secondary cementing layer at the interface with the primary CSH gel, significantly improving the continuity of the gel phase and interfacial adhesion, thereby enabling the overall permeability coefficient of the hardened body to reach a level of 1 x 10 -11 m / s or lower, meeting the requirements of high impermeability and high density between the outer ring soil and the tunnel segments of the shield tunnel.

[0057] The grouting process includes the following steps. Sp1: Online sensors, positioned at the front of the tunnel boring machine or in the synchronous grouting circulation loop, measure in real time the conductivity of the formation water, the concentrations of calcium and magnesium ions, and the temperature of the grout and the surrounding environment. Sensor data is sent to the data processing controller at 10-60 second intervals to reflect the formation permeability characteristics and ion environment of the current tunneling section. Sp2: Based on the deviation of the conductivity and ion concentration from preset thresholds, the data processing controller automatically adjusts the dosage of delayed hydration agent and ion-responsive polymer in the grouting mother liquor. For example, when the conductivity is high and the calcium ion concentration exceeds 50 mg / L, the dosage of delayed hydration agent is reduced by a predetermined ratio, while the dosage of ion-responsive polymer is increased, thereby shortening the initial setting time and improving early gelation. Conversely, when the conductivity and calcium ion concentration are low, the dosage of delayed hydration agent is increased, while the dosage of ion-responsive polymer is decreased, extending the flowability and rearrangement time of the grout, achieving automatic adjustment to adapt to different formation conditions.

[0058] Sp3, through frequency conversion adjustment of grouting pump speed and control of pipeline back pressure, achieves real-time adjustment of grouting speed within the range of 20 to 80 liters per minute. Based on the grouting pressure curve and existing empirical relationships, it controls the effective diffusion front length of grout in the shield tail gap to be stable within the range of 2 to 6 centimeters. During this stage, the large-scale hydration reaction of fast-hydrating silicate cement and activated aluminosilicate minerals is inhibited by the action of delayed hydration agent. The physical thixotropic network formed by bentonite and reversible thixotropic polymer undertakes the main bearing and stabilization functions, allowing the grout to fully diffuse and rearrange in the shield tail gap and surrounding soil pores. In Sp4, when the internal temperature of the grout increases by more than 25 to 35 degrees Celsius due to the combined effect of hydration heat release and ambient temperature, the coating material, such as polyvinyl alcohol film or aliphatic wax layer, softens and undergoes local rupture due to the internal and external pressure difference. When the pressure gradient formed by the grout in the shield tail space exceeds 0.05 to 0.15 MPa, the coating will also experience stress rupture due to shear stress and normal stress concentration. After the coating particles rupture, the calcium aluminate fast-setting powder and silicate precursor are rapidly released into the grout. The calcium aluminate fast-setting powder rapidly hydrates in a high pH environment to generate calcium aluminum hydrate. The silicon and aluminum oxide species released by the silicate precursor induce the formation of CASH and NASH gel networks, which interpenetrate and grow with the CSH gel network generated by the subsequent hydration of the fast-hydrated silicate cement. This allows the grout to complete the solidification sequence from the flowable stage to the rearranged structure stage and then to the rapid solidification stage from the shield tail side to the outer edge, ultimately forming a continuous and dense solidified layer between the outer ring of the tunnel segment and the surrounding strata.

[0059] To implement the above process, the hardware system for the grouting process includes an ion monitoring module, a grouting pump speed and pressure control module, a membrane rupture process monitoring module, and a data processing controller. The ion monitoring module is equipped with a conductivity sensor, calcium and magnesium ion selective electrodes, and a temperature compensation unit to measure the concentration of calcium and magnesium ions and conductivity in the grouting environment in real time, and maintains measurement accuracy through automatic cleaning and periodic calibration. The grouting pump speed and pressure control module uses a screw pump or plunger pump with a frequency converter driver, and installs inlet and outlet pressure sensors at key locations in the grouting pipeline to achieve closed-loop pressure control and flow regulation. The membrane rupture process monitoring module includes temperature sensors located near the shield tail gap and the grouting space, and pressure sensors to monitor changes in pressure gradient. By continuously collecting temperature and pressure changes over time, it identifies the time window and spatial range for membrane rupture of the coated particles. The data processing controller, implemented through an industrial computer or programmable logic controller, comprehensively analyzes the data collected by the above modules. Based on the preset solidification program curve, it adjusts the addition ratio of delayed hydration agent, ion-responsive polymer, and water replenishment in real time. At the same time, it issues commands to adjust the speed and pressure settings of the grouting pump, so that the grouting material can still complete the transition from the flowable stage, the rearrangeable structure stage, and the rapid solidification stage in a predetermined time and spatial sequence under different geological conditions and different shield tunneling conditions. This achieves a controllable solidification process in the on-site geological environment and ensures the quality of synchronous grouting of the shield and the safety of the tunnel structure. Specific Implementation Example 2:

[0061] like Figure 4 As shown, based on the technical solution of specific embodiment one, further application examples are given:

[0062] The tunnel section passes through a water-rich upper sand layer with a high water content and a permeability coefficient of 1×10⁻⁶. -3 Up to 5×10 -3 m / s, Ca in formation water 2+ With a concentration of approximately 68-92 mg / L and an electrical conductivity of approximately 1.4-1.8 mS / cm, the grout is highly susceptible to loss, segregation, and excessive diffusion without protection. This section requires the rapid formation of an anti-water-spreading network at the shield tail to prevent the grout from being dispersed by groundwater, while simultaneously achieving rapid shield tail sealing to improve the segment attitude control capability.

[0063] The mixing ratio system provided in the technical solution is adopted:

[0064] Rapidly hydrated silicate cement: 20 parts; activated aluminosilicate minerals: 12 parts; nano-silica powder: 2 parts; bentonite: 5 parts; reversible thixotropic polymer: 0.4 parts; delayed hydration agent: 0.05 parts (due to Ca...) 2+ (High, quantity adjusted to low); Coated calcium aluminate quick-setting powder: 2 parts; Coated silicate gel precursor: 0.8 parts; Ion-responsive polymer: 0.25 parts; Water-to-gel ratio: 0.55.

[0065] The monitoring data 30 minutes before grouting is as follows:

[0066] index numerical values System Response <![CDATA[Ca 2+ Concentration 75mg / L Triggering a shortened initial setting process <![CDATA[Mg 2+ Concentration 22mg / L Moderate impact electrical conductivity 1.6 mS / cm Determined to be a highly permeable environment Formation water temperature 18°C No additional adjustments required

[0067] The system automatically adjusts the dosage of delayed hydration agent to decrease by 20% and the dosage of ion-responsive polymer to increase by 25%.

[0068] Grouting process:

[0069] (1) Stage 1: 0-15 minutes (high flow, diffusible):

[0070] The grouting rate was set at 65 L / min. The diffusion front was monitored at approximately 5.2 cm. Thixotropic network dominated viscosity recovery, and the grout maintained good diffusivity. No segregation or bleeding was observed.

[0071] (2) Phase Two: 15-30 minutes (Rearrangeable Structure Phase):

[0072] With the infiltration of groundwater and Ca 2+ Enhanced coordination leads to the formation of local crosslinking points in the reversible thixotropic polymer, as monitored by the system.

[0073] The slurry viscosity increased by 28% compared to its outlet state. The local pH value increased from 12.2 to 12.6. The formation seepage direction became consistent, and the diffusion range tended to stabilize. The delayed hydration agent began to degrade, but the system still had no risk of premature setting.

[0074] (3) Stage 3: 30-55 minutes (membrane rupture and rapid gelation reaction):

[0075] The temperature accumulated from hydration to 26.3°C, and the pressure gradient reached 0.11 MPa, satisfying the dual triggering conditions, causing the coating layer to rupture: the calcium aluminum hydrate formed the initial gel framework within 10 minutes; the silicate precursor released Si-O. - This significantly accelerates CASH gel formation; the CSH gel begins to interpenetrate with the inorganic gel network.

[0076] At this point: the initial setting time was measured to be 46 minutes (approximately 35% shorter than the baseline), the gel's erosion resistance was significantly enhanced, and no long-distance slurry loss was observed in the sand layer.

[0077] The compressive strength at 6 hours reached 0.48 MPa; the strength at 28 days reached 3.1 MPa; and the permeability coefficient was 8.7 × 10⁻⁶. - 12 m / s; the grouting density at the shield tail is >99%, and the segment attitude deviation is reduced by 42% compared to the previous ring; there was no instance of grout being carried away by groundwater or the need for secondary grouting.

[0078] This system successfully suppressed the scouring of the grout by the sand layer water flow, accelerated the stabilization of the shield tail, and significantly improved the effect of synchronous grouting. Specific Implementation Example 3:

[0080] like Figure 5 As shown, based on the technical solutions of Specific Embodiment 1 and Specific Embodiment 2, further application examples are given:

[0081] The strata in the tunnel boring area are mainly soft plastic clay, which has poor self-stability but low permeability. 2+ With a concentration of only 6-12 mg / L and an electrical conductivity of 0.28-0.35 mS / cm, this type of formation is prone to problems such as insufficient grouting, incomplete diffusion, and excessively large voids in the later stages. The construction of this section needs to achieve long-term pumpability, flowability, and diffusion to prevent premature solidification of the grout before it has diffused.

[0082] Under this condition, the automatic adjustment module is adjusted as follows: the delayed hydration agent is increased to 0.10 parts; the ion-responsive polymer is reduced to 0.12 parts; other components are the same as in Specific Example 2. The purpose is to prolong the flowable phase and weaken the ion-induced acceleration effect.

[0083] Monitoring parameter: Ca 2+ 8 mg / L, Mg 2+ 6 mg / L, conductivity: 0.31 mS / cm, temperature: 15°C. The system, based on the preset curve, identified the environment as low-ion, low-permeability and entered the "extended diffusion program".

[0084] Grouting process Sp2-Sp4:

[0085] Phase 1: 0-25 minutes (Extended flow phase):

[0086] The grouting rate was set at 45 L / min to avoid excessive air incorporation. The diffusion front was approximately 3.4 cm, spreading into a "flattened ellipsoidal" structure. The physical thixotropic network provided the main structural stability. The clay layer exhibited slight adsorption, but did not significantly affect flowability. The delayed hydration agent effectively inhibited the early reaction between cement and aluminosilicate minerals.

[0087] Phase Two: 25-50 minutes (Rearrangement and Anti-segregation Phase):

[0088] The slurry viscosity increased by approximately 15% (lower than in the sand layer case, indicating a normal reaction). The controller dynamically adjusted the pump speed between 40-55 L / min. Due to the small porosity of the clay, diffusion was controlled by formation resistance, resulting in a stable but relatively uniform diffusion range. Diffusion was sufficient at this stage, and no visible premature setting occurred.

[0089] Phase 3: 50-90 minutes (film breaking and curing start):

[0090] The low ion layer results in a slow temperature rise, and the pressure gradient mainly comes from the shield tail clamping effect: the temperature changes slowly, rising from 15°C to 22°C; the pressure gradient rises to 0.13 MPa, which meets the conditions for membrane rupture.

[0091] The coating layer first ruptured at 62 minutes. After rupture, the calcium aluminum hydrate formed at a moderate rate, avoiding premature stiffening. NASH and CASH gels formed a uniform gel layer in the clay. CSH gel enhanced the overall strength in the later stage.

[0092] The initial setting time was approximately 78 minutes (significantly longer than that of the sand layer, meeting the design target); the 6-hour strength was 0.32 MPa; the 28-day strength was 2.7 MPa; and the permeability coefficient was 1.3 × 10⁻⁶. -11 m / s; uniform grouting density with no voids; subsequent segment posture remains stable with no secondary grouting required.

[0093] This grouting system successfully extended the flow time, achieved full diffusion, and cured smoothly after diffusion in clay strata, avoiding the problem of "premature hardening" and outperforming traditional cement-based synchronous grouting materials.

[0094] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a reference structure" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hybrid shield tunneling synchronous grouting material, characterized in that: The grouting material includes: 15-25 parts of fast-hydrating silicate cement; 8–15 parts activated aluminosilicate minerals; 1-3 parts nano-silicon powder; 4 to 7 parts bentonite; 0.2–0.5 parts of reversible thixotropic polymer; 0.05–0.10 parts of delayed hydration agent; 1-3 parts of coated calcium aluminate quick-setting powder; 0.5–1 part of coated silicate gel precursor; Delayed hydration agents inhibit the hydration of cement and aluminosilicate minerals within 0 to 20 minutes. Coated calcium aluminate fast-setting powder and coated silicate precursors enter the membrane breaking stage and produce a gel reaction within 20 to 60 minutes, enabling the slurry to form a controllable solidification sequence.

2. The hybrid shield tunneling synchronous grouting material according to claim 1, characterized in that: The coating thickness of the coated calcium aluminate rapid-setting powder is 2-20 μm, and the material is selected from polyvinyl alcohol, aliphatic wax or thermoplastic acrylic emulsion; by adjusting the coating thickness and melting point, the film breaking time of the coated particles is controlled by the coupling of three factors: temperature, pressure and pH.

3. The hybrid shield tunneling synchronous grouting material according to claim 1, characterized in that: The activated aluminosilicate minerals, under the action of a delayed hydration agent, inhibit the early-stage reaction. When the coated silicate precursor breaks down, the Si-O released by the precursor... - and Al-O - Upon entering the solution, it induces the formation of an inorganic gel network dominated by CASH / NASH, which interpenetrates with the CSH network generated by the subsequent hydration of silicates.

4. The hybrid shield tunneling synchronous grouting material according to claim 1, characterized in that: The reversible thixotropic polymer, with a shear rate from 0 s... -1 Increase to 100s -1 When shearing is applied, the viscosity decreases by 30%–60%, but recovers to 80%–95% of its original viscosity within 5 minutes. Furthermore, its chain segments contain weakly coordinating Ca. 2+ The side bases.

5. The hybrid shield tunneling synchronous grouting material according to claim 1, characterized in that: The ion-responsive polymer and Ca 2+ / Mg 2+ The coordination constant is in the range of 10² to 10³ L / mol, when the Ca in the aquifer water is... 2+ When the concentration is greater than 50 mg / L, the initial setting time of the grout is shortened by 20% to 40%. 2+ When the concentration is below 10 mg / L, the initial setting time is prolonged by 10% to 30%.

6. The hybrid shield tunneling synchronous grouting material according to claim 1, characterized in that: The microstructure of the grouting material satisfies the following characteristics: The pore size of the gel network is mainly distributed in the range of 10–500 nm; The ratio of CASH phase to CSH phase is between 1:1 and 1:3; Nano-silica powder forms uniformly dispersed secondary cementing points in the gel phase.

7. The grouting process of a hybrid shield tunnel synchronous grouting material according to any one of claims 1-6, characterized in that: The grouting process includes the following steps: Sp1, real-time measurement of formation water conductivity and Ca 2+ / Mg 2+ Concentration and temperature; Sp2. The dosage of delayed hydration agent and ion-responsive polymer is automatically adjusted based on conductivity and ion concentration. Sp3. Real-time adjustment of grouting speed to control the grouting material to maintain a low viscosity diffusion stage in the shield tail gap for 20 to 60 minutes; Sp4 triggers a rapid gelation reaction between calcium aluminate quick-setting powder and silicate precursor by coating particles to break the membrane, causing the slurry to gradually harden from the tail of the shield to the outer edge to form a continuous and dense solid.

8. The grouting process of a hybrid shield tunnel synchronous grouting material according to claim 7, characterized in that: The membrane rupture of the coated particles is triggered by the following two conditions: A. When the internal temperature of the solidified body rises above 25-35°C, the coating softens and ruptures. B. When the slurry pressure gradient is greater than 0.05-0.15 MPa, the cladding stress ruptures.

9. The grouting process of a hybrid shield tunnel synchronous grouting material according to claim 7, characterized in that: The real-time controlled grouting speed is in the range of 20-80 L / min, so that the grout forms a diffusion front length of 2-6 cm in the shield tail gap. The rheological network dominated by thixotropic polymer is established first, and then the inorganic gel network solidifies sequentially behind the diffusion front to form a solidified body.

10. The grouting process of a hybrid shield tunnel synchronous grouting material according to claim 7, characterized in that: The hardware components of the grouting process include: An ion monitoring module is used to measure Ca in the grouting environment in real time. 2+ / Mg 2+ concentration; Grouting pump speed and pressure control module; The membrane rupture process monitoring module includes temperature and pressure sensors; The data processing controller is used to adjust the dosage ratio of delayed hydration agent, ion-responsive polymer and water based on monitoring data, and to control the grouting speed and pressure.

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