Synchronous grouting material, preparation method thereof and application of synchronous grouting material in subsea tunnel shield construction

Abstract

The invention provides a synchronous grouting material, a preparation method thereof and application of the synchronous grouting material in subsea tunnel shield construction, and belongs to the technical field of building materials. The material system comprises a cementing material, sand, mixing water and an additive; the cementing material is composed of Portland cement clinker, calcined clay, limestone powder, nano silicon dioxide and calcium sulfate coagulation regulating components, wherein the calcined clay and the limestone powder are compounded according to a certain mass ratio; the nano silicon dioxide is introduced in the form of a water-phase pre-dispersed suspension. Through cooperative regulation and control of the LC3 composite gel system and the nano silicon dioxide, the stability, the pumpability and the early bearing capacity of the slurry can be improved while the use amount of the clinker is reduced, the long-term durability in the marine environment is improved, and the slurry is suitable for synchronous grouting of subsea tunnel shield construction.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a synchronous grouting material, its preparation method, and its application in shield tunneling of submarine tunnels. Background Technology

[0002] Synchronous grouting is used to fill the annular gap between the tunnel lining segments and the ground, in order to support the surrounding strata, control surface subsidence, and inhibit groundwater infiltration. In subsea tunnel engineering, grouting materials often face stringent requirements such as high external water pressure, chloride and sulfate ion erosion, long-distance pumping, and the need to quickly form load-bearing capacity after injection.

[0003] Existing synchronous grouting materials mostly use ordinary Portland cement (OPC) as the main cementing material, which has problems such as large clinker consumption and high carbon emissions. Furthermore, in marine erosion environments, its long-term impermeability and erosion resistance still have room for improvement. In addition, as the construction distance increases, the rheological stability of the grout becomes more susceptible to temperature changes, raw material fluctuations, and pumping shear, potentially leading to bleeding, segregation, or pipe blockage, thus affecting the grout fullness and the load-bearing capacity after ring formation.

[0004] Limestone calcined clay cement (LC3) uses calcined clay and limestone powder to synergistically replace part of the clinker, which can significantly reduce carbon emissions. However, in practical applications, the LC3 system may have problems such as slow early hydration, high water demand, and sensitivity to rheology and stability, making it difficult to simultaneously meet the comprehensive requirements of synchronous grouting for pumpability, low bleeding rate, and early bearing capacity.

[0005] Nano-silica can serve as a nucleus and active silicon source, promoting early reactions and improving microstructure, but it is prone to agglomeration and has poor dispersion stability. Direct dry mixing or insufficient dispersion may lead to increased water demand, decreased fluidity, or performance fluctuations. Therefore, it is necessary to develop an LC3-based synchronous grouting material suitable for submarine tunnel conditions, taking into account both low carbon emissions, environmental friendliness, and construction adaptability, and to provide its engineering preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a synchronous grouting material, its preparation method, and its application in the construction of submarine tunnel shield tunnels. This invention addresses the technical problems of existing synchronous grouting materials used in submarine tunnel shield construction, such as poor pumpability, high risk of bleeding and segregation, poor early bearing capacity and durability, high clinker consumption, and high carbon emissions.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a synchronous grouting material, comprising the following components: cementitious material, sand, mixing water, and additives; The mass ratio of the cementitious material to the sand is 1:0.15~0.35; The mass ratio of the cementitious material to the mixing water is 1:0.28~0.60; The dosage of the admixture is 0.05~1.0% of the mass of the cementitious material; The admixtures include polycarboxylate superplasticizers.

[0008] Furthermore, the cementitious material is composed of the following components by mass fraction: 8-90% silicate cement clinker, 6-58% calcined clay, 3-29% limestone powder, 0.5-2.5% nano-silica, and 0.3-4.5% calcium sulfate setting modifier.

[0009] Furthermore, the mass ratio of the calcined clay to the limestone powder is 1.5~2.5:1.

[0010] Furthermore, the calcium sulfate setting agent includes one or more of gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum.

[0011] Furthermore, the average particle size of the nano-silica is 10~100nm.

[0012] Furthermore, the flow cone time of the synchronous grouting material is 17~40s.

[0013] This invention provides a method for preparing the above-mentioned synchronous grouting material, comprising the following steps: Step 1) Dry mix silicate cement clinker, calcined clay, limestone powder and calcium sulfate setting agent according to the proportion, then add sand and continue dry mixing to obtain dry mix; Step 2) After mixing nano-silica and mixing water, pre-disperse the mixture to obtain a nano-silica suspension; Step 3) Mix the nano-silica suspension, dry mix and additives, and stir to obtain the synchronous grouting slurry.

[0014] Furthermore, in step 2), the pre-dispersion is performed under ultrasonic conditions, with an ultrasonic frequency of 20–60 kHz and a pre-dispersion time of 10–40 min.

[0015] Furthermore, in step 3), the mixing includes two stages: pre-stirring and stirring. The pre-stirring speed is 130~150 r / min, and the time is 30~60 s. The stirring is high-speed stirring, with a speed of 270~300 r / min and a time of 2~6 min.

[0016] The present invention also provides an application of the above-mentioned synchronous grouting material in synchronous grouting during shield tunneling construction of submarine tunnels.

[0017] The beneficial effects of this invention are: Compared with existing OPC-based synchronous grouting materials or LC3 slurries without effective dispersion of nano-silica, the present invention has at least the following beneficial effects: Low carbon: By partially replacing clinker with calcined clay and limestone powder, the amount of clinker used is reduced, thereby reducing the carbon emissions related to the materials.

[0018] Stability: After pre-dispersion in the aqueous phase, nano-silica works synergistically with the LC3 system to reduce bleeding and inhibit segregation, thereby improving the rheological stability during long-distance pumping.

[0019] Early coagulation: The nucleation and activity effects of nano-silica help promote early hydration and structural densification, which is beneficial for the rapid formation of load-bearing capacity after injection.

[0020] Durability: The hydration products and refined pore structure generated by the LC3 system are beneficial to improving impermeability and resistance to erosion ion penetration, making it suitable for marine erosion environments. Detailed Implementation

[0021] This invention provides a synchronous grouting material, comprising the following components: cementitious material, sand, mixing water, and additives; The mass ratio of the cementitious material to the sand is 1:0.15~0.35; The mass ratio of the cementitious material to the mixing water is 1:0.28~0.60; The dosage of the admixture is 0.05~1.0% of the mass of the cementitious material; The admixtures include polycarboxylate superplasticizers.

[0022] In this invention, the mass ratio of the cementitious material to the sand is preferably 1:0.18~0.30.

[0023] In this invention, the mass ratio of the gelling material to the mixing water is preferably 1:0.28~0.60.

[0024] In this invention, the amount of the admixture is preferably 0.10 to 0.80% of the mass of the cementitious material, and more preferably 0.50%.

[0025] In this invention, the cementitious material is composed of the following components by mass fraction: 8-90% silicate cement clinker, preferably 15-60%; 6-58% calcined clay, preferably 20-40%; 3-29% limestone powder, preferably 10-20%; 0.5-2.5% nano-silica, preferably 1.0-2.0%; and 0.3-4.5% calcium sulfate setting modifier, preferably 1.0-3.8%.

[0026] In this invention, the silicate cement clinker includes clinker sources that can be conventional silicate cement clinker or clinker sources provided by ordinary silicate cement (e.g., P·O 42.5 or P·O 52.5).

[0027] In this invention, the calcined clay is preferably obtained by calcining kaolin at 650-850°C.

[0028] In this invention, the limestone powder is preferably composed of calcium carbonate with a content of ≥85%.

[0029] In this invention, the sand is preferably quartz sand or manufactured sand, and the manufactured sand meets the particle size distribution requirements for shield tunneling synchronous grouting.

[0030] In this invention, the nano-silica is preferably nano-silica sol or powder, and more preferably powder.

[0031] In this invention, as a preferred embodiment, when the nano-silica is in powder form, it is pre-dispersed in an aqueous phase to form a suspension.

[0032] In this invention, the mass ratio of calcined clay to limestone powder is 1.5~2.5:1, preferably 1.8~2.3:1.

[0033] In this invention, the calcium sulfate setting agent includes one or more of gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum, preferably gypsum dihydrate or gypsum hemihydrate, and more preferably gypsum dihydrate.

[0034] In this invention, the average particle size of the nano-silica is 10~100nm, preferably 20~80nm.

[0035] In this invention, the flow cone time of the synchronous grouting material is 17~40s, preferably 20~35s, and more preferably 25~30s.

[0036] In this invention, by adjusting the yield of the water-reducing agent and the amount of mixing water, the slurry material can meet the target fluidity and stability.

[0037] This invention provides a method for preparing the above-mentioned synchronous grouting material, comprising the following steps: Step 1) Dry mix silicate cement clinker, calcined clay, limestone powder and calcium sulfate setting agent according to the proportion, then add sand and continue dry mixing to obtain dry mix; Step 2) After mixing nano-silica and mixing water, pre-disperse the mixture to obtain a nano-silica suspension; Step 3) Mix the nano-silica suspension, dry mix and additives, and stir to obtain the synchronous grouting slurry.

[0038] In this invention, in step 2), the pre-dispersion is performed under ultrasonic conditions, with the ultrasonic frequency being 20-60 kHz, preferably 30-50 kHz, and more preferably 35-45 kHz; the pre-dispersion time is 10-40 min, preferably 20-30 min, and more preferably 22-28 min.

[0039] In this invention, step 3) includes two stages of mixing: pre-stirring and stirring. The rotation speed of the pre-stirring is 130~150 r / min, preferably 140 r / min; the time is 30~60s, preferably 40~50s. The stirring is high-speed stirring, with a stirring speed of 270~300 r / min, preferably 285 r / min; the stirring time is 2~6 min, preferably 3~5 min.

[0040] In this invention, in step 3), the pre-mixing and high-speed mixing are preferably carried out using a planetary mortar mixer, and the purpose of high-speed mixing is to ensure thorough mixing.

[0041] The present invention also provides an application of the above-mentioned synchronous grouting material in synchronous grouting during shield tunneling construction of submarine tunnels.

[0042] In this invention, the application method of the synchronous grouting material in synchronous grouting during shield tunneling of submarine tunnels involves pumping and injecting the grout within a specified time window after mixing; injecting the grout into the annular void outside the tunnel segment through the synchronous grouting system at the tail of the shield, and ensuring full filling by using a dual control method of grouting pressure and injection volume; after injection, the grout gradually solidifies and hardens to form a support layer, reducing voids and inhibiting water seepage.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] A total of 1000 parts of cementitious materials were used. 600 parts of silicate cement clinker, 240 parts of calcined clay, 20 parts of gypsum dihydrate and 120 parts of limestone powder were dry-mixed in a mixer for 3 minutes. Then sand was added so that the mass ratio of sand to cementitious materials was 0.22. The mixture was dry-mixed for another 2 minutes to obtain the dry mix. 20 parts of nano-silica and mixing water (the mass ratio of mixing water to cementitious material is 0.40:1) were mixed and ultrasonically dispersed at 30 kHz for 20 min to obtain a nano-silica suspension. Then, it was mixed with dry mix and polycarboxylate superplasticizer (0.30% of the mass of cementitious material), stirred at low speed at 140 r / min for 30 s, and then stirred at high speed at 285 r / min for 3 min to obtain the synchronous grouting slurry.

[0046] Example 2

[0047] A total of 1000 parts of cementitious materials were used. 400 parts of silicate cement clinker, 360 parts of calcined clay, 40 parts of gypsum dihydrate and 180 parts of limestone powder were dry-mixed in a mixer for 3 minutes. Then sand was added so that the mass ratio of sand to cementitious materials was 0.25. The mixture was dry-mixed for another 2 minutes to obtain the dry mix. 20 parts of nano-silica and mixing water (the mass ratio of mixing water to cementitious material is 0.48:1) were mixed and ultrasonically dispersed at 30 kHz for 20 min to obtain a nano-silica suspension. Then, it was mixed with dry mix and polycarboxylate superplasticizer (mass of 0.50% of cementitious material) and stirred at low speed at 150 r / min for 30 s, and then stirred at high speed at 270 r / min for 3 min to obtain synchronous grouting slurry.

[0048] Example 3

[0049] A total of 1000 parts of cementitious materials were used. 455 parts of silicate cement clinker, 330 parts of calcined clay, 45 parts of gypsum dihydrate and 150 parts of limestone powder were dry-mixed in a mixer for 3 minutes. Then sand was added so that the mass ratio of sand to cementitious materials was 0.20. The mixture was dry-mixed for another 2 minutes to obtain the dry mix. 20 parts of nano-silica and mixing water (the mass ratio of mixing water to cementitious material is 0.35:1) were mixed and ultrasonically dispersed at 30 kHz for 20 min to obtain a nano-silica suspension. Then, it was mixed with dry mix and polycarboxylate superplasticizer (mass of 0.50% of the cementitious material) and stirred at low speed at 130 r / min for 30 s, and then stirred at high speed at 300 r / min for 3 min to obtain the synchronous grouting slurry.

[0050] Comparative Example 1

[0051] Unlike Example 1, in this comparative example, nano-silica was removed from the system to obtain a slurry.

[0052] Comparative Example 2

[0053] Unlike Example 1, in this comparative example, the nano-silica powder was added directly to the system without pre-dispersion to obtain a slurry.

[0054] Performance testing

[0055] First, nano-silica was dispersed in the mixing water using ultrasonic dispersion to form a uniform nano-silica suspension (NS–watersuspension). This suspension was then added to the dry cementitious material components during stirring to obtain the synchronous grouting slurry. A total of 18 formulations were prepared within the composition range declared in this application to verify the plasticity, stability, early hardening performance, and serviceability in water-bearing environments of the grouting material. Specifically, the flow cone method was used to test the fluidity of the synchronous grouting slurry; stability was assessed by the bleeding rate (%) after a specified settling time and by visual segregation observation; early performance was verified by the 1-day compressive strength under specified curing conditions; and durability in water-bearing service environments was evaluated by the 28-day water-land strength ratio (WLSR). Three representative formulations were selected, and the quantitative verification range of various properties of the resulting grouting materials is summarized in Table 1.

[0056] Table 1. Test data of slurries obtained under different raw material systems

[0057] The results in Table 1 show that the formulation disclosed in this invention can achieve a flow time within the pumpable range of the slurry material, a low bleeding rate, improved early strength, and a high strength retention rate (WLSR ≥ 80%) in an aqueous environment. All of these results support the usability of the material.

[0058] As can be seen from the above embodiments, the present invention provides a synchronous grouting material, its preparation method, and its application in shield tunneling of submarine tunnels. This material, while reducing clinker usage and carbon emissions, possesses adjustable working performance, lower risk of bleeding and segregation, good pumpability, high early bearing capacity, and durability adapted to marine erosion environments. According to Example 1 and Comparative Examples 1-2, the improvement in grout stability and early performance is insufficient, indicating that the introduction of nano-silica aqueous pre-dispersion and the LC3 system have a synergistic effect.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A synchronous grouting material, characterized in that, It includes the following components: cementitious materials, sand, mixing water, and additives; The mass ratio of the cementitious material to the sand is 1:0.15~0.35; The mass ratio of the cementitious material to the mixing water is 1:0.28~0.60; The dosage of the admixture is 0.05~1.0% of the mass of the cementitious material; The admixtures include polycarboxylate superplasticizers.

2. The synchronous grouting material according to claim 1, characterized in that, The cementitious material is composed of the following components by mass fraction: 8-90% silicate cement clinker, 6-58% calcined clay, 3-29% limestone powder, 0.5-2.5% nano-silica, and 0.3-4.5% calcium sulfate setting modifier.

3. The synchronous grouting material according to claim 2, characterized in that, The mass ratio of the calcined clay to limestone powder is 1.5~2.5:

1.

4. A synchronous grouting material according to claim 2 or 3, characterized in that, The calcium sulfate setting agent includes one or more of dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum.

5. The synchronous grouting material according to claim 2, characterized in that, The average particle size of the nano-silica is 10~100nm.

6. The synchronous grouting material according to claim 1, characterized in that, The flow cone time of the synchronous grouting material is 17~40s.

7. The method for preparing the synchronous grouting material according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1) Dry mix silicate cement clinker, calcined clay, limestone powder and calcium sulfate setting agent according to the proportion, then add sand and continue dry mixing to obtain dry mix; Step 2) After mixing nano-silica and mixing water, pre-disperse the mixture to obtain a nano-silica suspension; Step 3) Mix the nano-silica suspension, dry mix and additives, and stir to obtain the synchronous grouting slurry.

8. The method for preparing a synchronous grouting material according to claim 7, characterized in that, In step 2), the pre-dispersion is performed under ultrasonic conditions, with an ultrasonic frequency of 20–60 kHz and a pre-dispersion time of 10–40 min.

9. A method for preparing a synchronous grouting material according to claim 7 or 8, characterized in that, In step 3), the mixing includes two stages: pre-stirring and stirring. The pre-stirring speed is 130~150 r / min and the time is 30~60s. The stirring is high-speed stirring with a speed of 270~300 r / min and a time of 2~6min.

10. The application of the synchronous grouting material according to any one of claims 1 to 6 in synchronous grouting during shield tunneling construction of submarine tunnels.

Images