A synchronous grouting material for high water pressure ultra-large shield tunnels and its preparation method

Abstract

This invention discloses a synchronous grouting material for high-water-pressure ultra-large shield tunnels and its preparation method, belonging to the technical field of cement-based materials. The synchronous grouting material for high-water-pressure ultra-large shield tunnels consists of two components, A and B. Component A is cement slurry, including cement, bentonite, highly active mineral admixtures, viscosity modifiers, stabilizers, and water; component B is a water glass solution. The volume ratio of component A to component B is 10–13:1. The synchronous grouting material of this invention has good water dispersibility, slow gel time, fast setting time, and high water erosion resistance. The gel time and setting time of the slurry are controllable and adjustable, avoiding slurry blockage and quickly and effectively filling the gap between the tunnel segments and the surrounding soil. Simultaneously, the slurry exhibits good cohesion in water-rich environments and is not prone to segregation and dispersion, meeting the performance requirements of synchronous grouting materials for high-water-pressure, ultra-large-diameter shield tunnels.

Description

Technical Field

[0001] This invention belongs to the field of grouting material technology, specifically relating to a synchronous grouting material for high water pressure ultra-large shield tunnels and its preparation method. Background Technology

[0002] With the accelerating pace of urbanization, major cities are actively constructing subway tunnels and river-crossing passages to alleviate urban traffic congestion and promote intercity development and cooperation. These projects often utilize shield tunneling, resulting in a continuous increase in the diameter of shield tunnels. Compared to traditional shield tunnels, the increased diameter leads to a significant increase in buoyancy after the tunnel segments are assembled and exit the shield tail. This can cause severe segment uplift and cracking, while also threatening shield attitude control. The shield machine is prone to "head-bumping" during excavation, and excessive shield attitude deviation can further complicate segment assembly, causing misalignment or even damage, severely impacting tunnel waterproofing and subsequent operational safety.

[0003] For ultra-large diameter shield tunnels, the spacing between grouting ports is much greater than that of ordinary subway shield tunnels. If the setting time of the grouting material is too short, it can easily lead to blockage of the grouting pipes and increased construction difficulty. If the setting time is too long, it can cause the tunnel segments to float after detaching from the shield tail. In water-rich environments such as highly permeable strata, water-rich karst strata, and water-rich rock strata with well-developed fissures, the gaps at the shield tail are filled with groundwater, which can easily cause dilution of the grouting slurry during synchronous grouting operations. This leads to significant changes in parameters such as the water-cement ratio of the slurry, resulting in underwater dispersion of the grouting material, prolonged setting time, and severely insufficient later strength. Simultaneously, the lost cementitious material can pollute nearby water bodies, causing serious impacts on the ecological environment. Synchronous grouting at the shield tail plays a crucial role in controlling segment floatation, reducing ground settlement, transferring loads, and constructing the first waterproof and seepage-resistant barrier. Ultra-large diameter shield tunnels in water-rich environments place even higher demands on the quality of synchronous grouting at the shield tail.

[0004] Synchronous grouting materials are generally classified into single-component grouts and two-component grouts according to the grouting method. Single-component grouts have better fluidity but a longer setting time, which is not conducive to segment buoyancy resistance. Two-component grouts have a faster setting time, which is beneficial to segment buoyancy resistance. Currently, in practical engineering applications, the setting time of two-component grouts is mainly controlled by adjusting the properties and dosage of water glass. However, its setting time is difficult to control precisely, and pipe blockage is a common problem during actual construction, limiting its widespread application in shield tunnel engineering. At the same time, two-component grouts also have the problem of excessively fast gelation time. After the A and B grouts are mixed, they reach a physical gel state within tens of seconds or even several seconds, losing fluidity. According to relevant literature, retarders such as tartaric acid and sodium citrate can be introduced to adjust the gel time of two-component grouts. However, retarders mainly affect the setting time by influencing the hydration of cement and other cementitious components, and have little effect on the physical gel time of the grout, thus failing to achieve the purpose of adjusting the gel time of the grout.

[0005] Furthermore, the common practice to address the poor water dispersibility of shield tail grouting materials is to introduce anti-dispersing admixtures to increase particle cohesion. These admixtures are typically cellulose ethers and acrylic flocculants, which, while enhancing the underwater anti-dispersibility of the grout, also significantly affect its fluidity and setting time. In summary, to address the urgent needs for high fluidity, rapid setting, and anti-dispersibility in synchronous grouting materials, and to solve key technical challenges arising from changes in the service environment, it is imperative to develop a synchronous grouting material suitable for high-water-pressure ultra-large shield tunnels. Summary of the Invention

[0006] To address the issues of flowability, dispersibility, gel time, and setting time in existing synchronous grouting materials, this invention provides a synchronous grouting material for high-water-pressure, ultra-large diameter shield tunnels. This grouting material consists of two components, A and B, where component A is cement grout and component B is a water glass solution. The gel time and setting time of the grouting material described in this invention are controllable and adjustable, effectively preventing grout blockage and enabling rapid filling of the gap between the tunnel segments and the surrounding soil. Simultaneously, the grout exhibits excellent resistance to water dispersibility and high resistance to water erosion in water-rich environments, ensuring that the grout does not disperse or segregate underwater. This meets the performance requirements of synchronous grouting materials for high-water-pressure, ultra-large diameter shield tunnels.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A synchronous grouting material for high water pressure ultra-large shield tunnels is composed of two components, A and B. Component A is cement grout, which includes cement, bentonite, highly active mineral admixtures, viscosity modifiers, stabilizers and water. Component B is water glass solution.

[0009] The mass ratio of each component in the A-component cement slurry is as follows:

[0010]

[0011] The stabilizer comprises a thickening component, an ion precipitation component, and a retarding component.

[0012] The water glass solution of component B has a Baumé degree of 30–40° and a modulus of 3.2.

[0013] The volume ratio of component A to component B is 10 to 13:1.

[0014] The highly active mineral additive is selected from any one or a mixture of two of metakaolin and kaolin.

[0015] The viscosity modifier is any one or a mixture of two of the following: fine ceramsite powder and attapulgite.

[0016] The size of the ceramsite fine powder is <80μm.

[0017] The cement is a mixture of any two or three of the following: ordinary Portland cement, sulfoaluminate cement, and aluminate cement. It must contain Portland cement, and the Portland cement content must be no less than 70% of the total cement mass.

[0018] The thickening component is one or a mixture of two of water-soluble cellulose ethers and bio-gels.

[0019] The precipitated component is one or a mixture of sodium aluminate, sodium sulfate, sodium sulfite, and sodium phosphate.

[0020] The retarding component is one or more of sodium saccharide, sodium citrate, tartaric acid, ammonium dihydrogen phosphate, and sodium tripolyphosphate.

[0021] The mass ratio of the thickening component, ion precipitation component, and retarding component in the stabilizer is 3-5:2-6:2-5.

[0022] This invention also provides a method for preparing the synchronous grouting material for high water pressure ultra-large shield tunnels, which specifically includes the following steps:

[0023] (1) Add water and bentonite material according to the mass ratio and stir at high speed to obtain a uniformly dispersed bentonite suspension.

[0024] (2) Add the stabilizer to the prepared bentonite suspension, stir evenly, and then add cement, highly active mineral admixture and viscosity modifier material all at once, stir evenly to obtain component A;

[0025] (3) The synchronous grouting material can be prepared by directly mixing and blending the cement slurry component A and the water glass component B.

[0026] The beneficial effects of this invention are:

[0027] This invention addresses the specific requirements of grouting materials for high-water-pressure ultra-large shield tunnels. By introducing highly active mineral admixtures, viscosity modifiers, and stabilizers, the viscosity, ionic state, and hydration activity of component A cement grout are controlled. This ensures that component A exhibits good performance stability, moderate viscosity, and controllable hydration process before mixing with component B. Furthermore, by adjusting the mixing ratio of components A and B, the bleeding rate, gel time, setting time, and water dispersibility of the grouting material are improved. Ultimately, this invention achieves slow gelation and rapid setting of the grout, excellent water dispersibility and water erosion resistance. It solves many problems in existing grouting material preparation technologies, such as the inability to coordinate gelation and setting times, poor underwater water dispersibility resistance, and the need for secondary grouting. It effectively fills the voids between the tunnel segments and the surrounding soil, while also helping to control segment floating and deformation, ensuring high-quality, stable, and efficient project progress. Detailed Implementation

[0028] The embodiments of the present invention will now be described in detail. However, the present invention can be implemented in many different forms, and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the various embodiments of the invention and various modifications suitable for particular intended applications.

[0029] To verify the superior performance of the synchronous grouting material of the present invention, the following embodiments and comparative experiments were conducted, with the comparative experiments based on the composition of the synchronous grouting material in Example 1. The preparation methods of the synchronous grouting material in the embodiments and comparative examples of the present invention are as follows:

[0030] First, pour the weighed water into a mixing pot, then add bentonite material and stir for 3-4 minutes using a high-speed mixer to obtain a uniformly dispersed bentonite suspension. Add the stabilizer to the prepared bentonite suspension and stir for about 1 minute. Finally, add the cement, highly active mineral admixture, and viscosity modifier material all at once, and stir for another 1-2 minutes to obtain the required two-liquid slurry component A. Then, directly mix the cement slurry component A with the water glass component B until they are evenly combined. The volume ratio of component A to component B is used to prepare the synchronous grouting material.

[0031] In Examples 1-10 and Comparative Examples 1-8, the ordinary silicate cement used was Helin P·O 42.5 silicate cement, and the early-strength cement was a 1:1 mixture of 52.5 sulfoaluminate cement and CA70 aluminate cement. Sodium-based bentonite with a density of 2.56 g / cm³ and a moisture content of 10-12% was used. Metakaolin was used as the high-activity mineral admixture. A sodium silicate aqueous solution with a Baume degree of 40° and a modulus of 3.2 was selected. The viscosity modifier was a mixture of ceramsite powder and attapulgite, with the specific proportions shown in Table 1. The ceramsite powder had a particle size of 75 μm. The specific proportions of each component in the synchronous grouting material are shown in Table 1, and the composition of each component in the stabilizer is shown in Table 2.

[0032] The components and contents of the synchronous grouting materials in each embodiment and comparative example are shown in Table 1.

[0033] Table 1. Components and contents of synchronous grouting materials in Examples 1-10 and Comparative Examples 1-8

[0034]

[0035]

[0036] Table 2. Stabilizer components in synchronous grouting materials of Examples 1-10 and Comparative Examples 1-8.

[0037] Thickening components Precipitated components Retarding components Example 1 Water-soluble cellulose ethers Sodium aluminate tartaric acid Example 2 bio-glue Sodium sulfate Sodium citrate Example 3 Water-soluble cellulose ethers Sodium sulfite Ammonium dihydrogen phosphate Example 4 bio-glue Sodium phosphate Sodium tripolyphosphate Example 5 Water-soluble cellulose ethers Sodium aluminate Sodium sugar Example 6 bio-glue Sodium aluminate tartaric acid Example 7 Water-soluble cellulose ethers Sodium sulfate Sodium citrate Example 8 bio-glue Sodium sulfite Ammonium dihydrogen phosphate Example 9 Water-soluble cellulose ethers Sodium phosphate Sodium tripolyphosphate Example 10 bio-glue Sodium sulfate Sodium citrate Comparative Example 1 none none none Comparative Example 2 Water-soluble cellulose ethers Sodium aluminate tartaric acid Comparative Example 3 Water-soluble cellulose ethers Sodium aluminate tartaric acid Comparative Example 4 Water-soluble cellulose ethers Sodium aluminate tartaric acid Comparative Example 5 Water-soluble cellulose ethers Sodium aluminate tartaric acid Comparative Example 6 Water-soluble cellulose ethers Sodium aluminate tartaric acid Comparative Example 7 Water-soluble cellulose ethers Sodium aluminate tartaric acid Comparative Example 8 Water-soluble cellulose ethers none tartaric acid

[0038] Application Examples

[0039] The synchronous grouting materials obtained in Examples 1-10 and the comparative synchronous grouting materials obtained in Comparative Examples 1-8 were tested for grout bleeding rate, gel time, setting time, compressive strength, and water-to-land strength ratio. Bleeding rate was tested using the method described in T-CECS563-2018 "Technical Specification for Application of Synchronous Grouting Materials in Shield Tunneling," using a 250mL graduated cylinder to test the bleeding rate of liquid A of the two-component grout after 3 hours. The gel time was tested using the inverted cup method, i.e., the time when liquids A and B, after mixing, form a gel and exhibit a "cup-hanging" phenomenon. Setting time was determined using the setting time test method in JGJ / T 70-2009 "Standard for Basic Performance Test Methods of Building Mortar," using a 30mm² probe. 2 A penetration resistance of 15N is considered a sign that the grout has reached the settling state. Compressive strength was tested using a φ50mm*100mm mold, demolded after 24 hours, and then cured in water. Compressive strength was tested after 1 day, 28 days, and 90 days. The water-to-land strength ratio was tested using the method specified in T-CECS563-2018, "Technical Specification for Application of Synchronous Grouting Materials in Shield Tunneling".

[0040] The slurry bleeding rate, gel time, setting time, compressive strength, and water-to-land strength ratio were tested respectively, and the test results are shown in Table 3.

[0041] Table 3. Test results of grouting materials in Examples 1-10 and comparative grouting materials in Comparative Examples 1-8.

[0042]

[0043] As can be seen from the data in Examples 1-10 in Table 3, the synchronous grouting material provided by the present invention can achieve controllable and adjustable gel time and setting time, as well as excellent resistance to water dispersibility and water erosion. It has the following performance indicators: bleeding rate <0.1%, gel time 50s~30min, setting time 2h~6h; 1d compressive strength (unconfined compressive strength) ≥500KPa, 28d strength ≥2.5MPa, 90d strength ≥4.0MPa; 28d water-land strength ratio >75%, 90d water-land strength ratio >65%. This grouting material is suitable for high water pressure ultra-large diameter shield tunnels.

[0044] As shown in Examples 1-4, while keeping the slurry composition and the dosage of other components constant, adjusting the relative dosage of the three components in the stabilizer can regulate the slurry gel time and setting time. Compared with Example 1, in Example 2, the dosage of the precipitating component of the stabilizer is reduced, while the dosages of the retarding and thickening components are increased, resulting in a shorter slurry gel time, a longer setting time, and a slight improvement in the water-to-land strength ratio. In Example 3, the dosages of the precipitating and thickening components of the stabilizer are increased, significantly extending the slurry gel time, but having little effect on the setting time. In Example 4, the dosages of the precipitating and retarding components of the stabilizer are further increased, significantly extending both the slurry gel time and setting time. The longer gel-setting time also reduces the early compressive strength of the slurry, but has little effect on the later strength and the water-to-land strength ratio.

[0045] Comparing the data of Comparative Examples 1-8 in Table 3 with the data of Example 1, it can be seen that the synchronous grouting material of the present invention regulates the slurry viscosity, solution ionic state and hydration activity of cement slurry by introducing highly active mineral admixtures, viscosity modifiers and stabilizers, and by adjusting the mixing ratio of component A and component B, a synchronous grouting material with synergistic slow gelation and fast setting, excellent water dispersibility and high water erosion resistance is prepared. However, these components influence each other in combination, rather than existing independently.

[0046] Comparing the data of Comparative Examples 1-8 in Table 3 with the data of Example 1, it can be seen that Comparative Example 1 lacks a stabilizer. The stabilizer mainly improves the stability of the slurry and adjusts the gel time and setting time of the slurry. Therefore, without the stabilizer, the slurry bleeding rate increases, the stability deteriorates, the resistance to water dispersibility is poor, the water-land strength ratio of the matrix decreases significantly, and the gel time and setting time of the slurry are significantly shortened. In actual application, the construction operation time is short and the risk of pipe blockage is easy to occur.

[0047] Comparative Example 2 lacks a viscosity modifier. A viscosity modifier further increases the viscosity of the slurry on the basis of the stabilizer, while having little effect on the slurry setting time. Therefore, the lack of a viscosity modifier increases the slurry bleeding rate and significantly reduces the water-to-land strength ratio of the matrix.

[0048] Comparative Example 3 lacks highly active mineral admixtures. The main function of highly active mineral admixtures is to change the type of hydration products of the slurry. The hydration products generated are mostly zeolite-like substances. Compared with conventional CH / CSH hydration products, zeolite-like substances have better water resistance. Therefore, the lack of highly active mineral admixtures results in poor water resistance of the grouting material and a decrease in the water-land strength ratio.

[0049] In Comparative Example 4, early-strength cement was lacking, and ordinary Portland cement was used entirely as a substitute. The formation of the early-stage rapid-setting structure of the two-liquid slurry mainly depends on the dissolution of tricalcium silicate in the cement to generate calcium ions. At the same time, silicate ions in water glass react with calcium ions to form gel. However, the content of tricalcium silicate in early-strength cement is extremely low or non-existent. Its main components are calcium sulfoaluminate or calcium aluminate. Under the promotion of ion precipitation components, it reacts with gypsum in cement to form ettringite, which is beneficial to shortening the setting time of the slurry. Therefore, the gel time of the slurry is shortened after the lack of early-strength cement, but the setting time is delayed.

[0050] In Comparative Example 5, ordinary Portland cement was not used and all of them were replaced with early-strength cement. Compared with Example 1, the gel time and setting time of the two-liquid slurry were significantly delayed, the slurry was in a non-fluid state for a long time, the bleeding rate increased, the 1-day compressive strength was reduced, and the water-to-land strength ratio also decreased significantly.

[0051] In Comparative Example 6, the volume ratio of component A to component B was 8:1. The gel time, setting time, and compressive strength of the two-liquid slurry were all related to the ratio of components A and B. Generally, the higher the content of calcium ions and silicate ions in the slurry, the shorter the gel time and setting time, and the higher the compressive strength of the matrix. Therefore, compared with Example 1, it can be seen that reducing the volume ratio of components A to B to 8:1 means that while keeping the amount of component A unchanged, the amount of component B was increased. However, since component B is a water glass solution with a Baume degree of 30-40°, of which 60% is water, when components A and B are mixed, the water glass dilutes the A solution, increasing the spacing between solid particles in the slurry. The spatial flocculation structure cannot be formed immediately, and the gel time of the slurry is prolonged. However, due to the increase in the total amount of silicate ions, the setting time of the slurry is shortened, and its compressive strength gradually increases.

[0052] In Comparative Example 7, the volume ratio of component A to component B was 15:1. Compared with Example 1, while keeping the amount of component A unchanged, the amount of component B was reduced, thus shortening the gelation time of the slurry, prolonging the setting time, and reducing the compressive strength of the matrix.

[0053] In Comparative Example 8, the stabilizer lacked precipitating components. Compared to Example 1, the removal of precipitating components while keeping the dosage of other components in the stabilizer unchanged resulted in a significant reduction in the gelation time of the slurry, but other performance data of the slurry did not change significantly.

[0054] Although the invention has been shown and described with reference to specific embodiments, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the claims and their equivalents.

Claims

1. A synchronous grouting material for high-water-pressure ultra-large shield tunnels, characterized in that, It consists of two components, A and B. Component A is cement slurry, which includes cement, bentonite, highly active mineral admixtures, viscosity modifiers, stabilizers and water. Component B is water glass solution. The mass ratio of each component in the A-component cement slurry is as follows: 175-225 parts cement; 75-125 parts bentonite; 80-95 parts of highly active mineral additives; 5-15 parts viscosity modifier; Stabilizer 7-16 parts; 710-790 parts water; The highly active mineral additive is selected from any one or a mixture of two of metakaolin and kaolin. The viscosity modifier is any one or a mixture of two of the following: fine ceramsite powder and attapulgite. The stabilizer comprises a thickening component, an ion precipitation component, and a retarding component; The thickening component is one or a mixture of two of water-soluble cellulose ethers and bio-glue; The ion precipitate component is one or a mixture of sodium aluminate, sodium sulfate, sodium sulfite, and sodium phosphate. The retarding component is one or more of sodium saccharide, sodium citrate, tartaric acid, ammonium dihydrogen phosphate, and sodium tripolyphosphate; The volume ratio of component A to component B is 10~13:1; The cement is a mixture of any two or three of ordinary silicate cement, sulfoaluminate cement, and aluminate cement, wherein silicate cement accounts for no less than 70% of the cement mass.

2. The synchronous grouting material for high water pressure ultra-large shield tunnels according to claim 1, characterized in that, The water glass solution of component B has a Baumé degree of 30-40° and a modulus of 3.

2.

3. The synchronous grouting material for high water pressure ultra-large shield tunnels according to claim 1, characterized in that, The mass ratio of the thickening component, ion precipitation component, and retarding component in the stabilizer is 3-5:2-6:2-5.

4. The synchronous grouting material for high water pressure ultra-large shield tunnels according to claim 1, characterized in that, The size of the ceramsite fine powder is <80μm.

5. The method for preparing the synchronous grouting material for high water pressure ultra-large shield tunnels according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Add water and bentonite material according to the mass ratio and stir at high speed to obtain a uniformly dispersed bentonite suspension. (2) Add the stabilizer to the prepared bentonite suspension, stir evenly, and then add cement, highly active mineral admixture and viscosity modifier material all at once, stir evenly to obtain component A; (3) The synchronous grouting material can be prepared by directly mixing and blending the cement slurry component A and the water glass component B.

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