CN108046653B

CN108046653B - External admixture for shield single-liquid synchronous grouting

Info

Publication number: CN108046653B
Application number: CN201711391812.3A
Authority: CN
Inventors: 田萌; 王伟山; 王绍华; 徐健; 冯中军
Original assignee: Shanghai Sunrise High Molecular Material Co ltd
Current assignee: Shanghai Sunrise High Molecular Material Co ltd
Priority date: 2017-12-21
Filing date: 2017-12-21
Publication date: 2020-07-07
Anticipated expiration: 2037-12-21
Also published as: CN108046653A

Abstract

The invention discloses an external admixture for shield single-fluid synchronous grouting, which comprises the following components in percentage by weight: 30-50% of polyacrylate, 0.5-10% of polycarboxylic acid superplasticizer, 1.0-5.0% of super-strong crystal nucleus early strength agent, 0.01-1.5% of bubble regulator, 0.01-1.5% of rheology regulator, 0.01-5% of retarder and the balance of water. The invention can be suitable for different grades of fly ash materials (such as F-type (low-calcium ash), C-type (high-calcium ash) or composite ash) and different types of molding sand (such as river sand, sea sand or machine-made sand), the obtained synchronous grouting slurry has high specific gravity, high initial shear strength, good long-term fluidity and good filling performance, and can better prevent the settlement of shield construction.

Description

External admixture for shield single-liquid synchronous grouting

Technical Field

The invention relates to an external admixture for a shield construction wall rear synchronous grouting material, and belongs to the field of filling materials of shield construction gaps.

Background

When the shield method is adopted for construction, because the outer diameter of the shield is larger than the outer diameter of the tunnel, after the tail of the shield machine is separated from the segment, an annular gap exists between the segment and the stratum, so that after the segment is assembled, a proper amount of grouting material with certain early strength and final strength is filled into the gap under certain grouting pressure to support the surrounding soil, reduce stratum loss and control ground settlement so as to ensure the safety of the tunnel structure and the surrounding environment.

The shield construction grout in Shanghai area generally adopts a single-liquid synchronous grouting system, and the single-liquid synchronous grouting material mainly comprises the following components in parts by weight: cement (lime or gypsum), fly ash, bentonite, medium and fine sand, admixture and the like, and can be divided into inert slurry and hardenable slurry according to whether the material contains the cement or not.

Lime, fly ash, sand and bentonite in synchronous grouting are bulk materials, the current low-calcium ash sources are relatively tense, and high-calcium ash can be considered to replace low-calcium ash. Moreover, the environmental protection requirement is more and more strict, the requirement on sand production is more and more strict, the river sand amount is less and the quality is poorer and more, the mud content is higher and more, the sea sand resource is rich, but the utilization rate of the sea sand in engineering is relatively lower, the high-calcium ash and the sea sand are used for replacing the low-calcium ash and the river sand respectively, and the slurry cost can be reduced on the premise of not influencing the slurry performance. When the high-calcium ash replaces the low-calcium ash, the initial shear strength cannot be achieved, and a serious problem occurs; the problem of obvious reduction of fluidity when the sea sand replaces the river sand is solved, and the pumping requirement cannot be met. And because bentonite, gypsum or lime and other materials are added into the single-liquid type slurry, the commercial synchronous grouting admixture is mainly composed of polycarboxylic acid, and the slurry has poor fluidity and serious bleeding when the materials are changed, and cannot meet the requirements of initial shear strength and long-term fluidity of the slurry. At present, high-calcium ash replaces low-calcium ash or sea sand replaces river sand, and a mature technical scheme is not provided in shield construction engineering.

Disclosure of Invention

The invention aims to provide an admixture for single-liquid synchronous grouting of a shield, aiming at the problems in the prior art, the admixture is added with a super-strong crystal nucleus early strength agent to improve the initial shear strength of synchronous grouting slurry, a rheological regulator is added to improve the bleeding problem of the slurry, and a good bubble regulator and a retarder are added, so that the inert slurry has construction performance for 20h, and the initial shear strength and the fluidity of the slurry meet the construction requirements in the shield construction process of replacing low-calcium ash with high-calcium ash or replacing river sand with sea sand, the construction is convenient, the construction cost can be reduced, and when the admixture is used for materials of different grades, the obtained slurry has good pumping performance and slurry stability.

The specific technical scheme for realizing the purpose of the invention is as follows:

the admixture for shield single-fluid synchronous grouting is prepared by mixing and stirring the following components in percentage by weight:

the super-strong crystal nucleus early strength agent is a semitransparent calcium silicate gel solution prepared by a precipitation method, soluble calcium salt and sodium silicate are used as raw materials, the calcium-silicon ratio is 0.8-2.0, and the particle size is 50-350 nm.

The external additive for synchronous grouting is characterized in that polyacrylate is a homopolymer of acrylic acid, or a binary or ternary copolymer of acrylic acid, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid, and the weight average molecular weight of the external additive is 10000-1000000.

The additive for single-liquid synchronous grouting is characterized in that the water reducing rate of the polycarboxylic acid superplasticizer is 20-30%, and the weight average molecular weight of the polycarboxylic acid superplasticizer is 10000-80000.

The external admixture for single-liquid synchronous grouting is characterized in that the rheological regulator is one or a mixture of hydroxypropyl xanthan gum, maltodextrin, hydroxyethyl cellulose and guar gum.

The external additive for single-liquid synchronous grouting is prepared by compounding an air entraining agent and a defoaming agent, wherein the air entraining agent is one or a mixture of sodium dodecyl sulfate, sodium cocoyl alanine, cocamidopropyl hydroxysultaine and sodium lauroyl sarcosinate; the defoaming agent is one or a mixture of organic silicon defoaming agent and modified polyether defoaming agent.

The external admixture for single-fluid synchronous grouting is characterized in that the retarder is one or a mixture of calcium gluconate, sodium citrate and potassium tartrate.

The admixture can meet the shield construction requirement of replacing low-calcium ash with high-calcium ash or replacing river sand with sea sand, has good fluidity and excellent performance, is convenient to construct, and can reduce the construction cost.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.

Wherein the sodium polyacrylate is sodium salt of acrylic acid homopolymer, polyacrylic acid/acrylamide salt is copolymer of acrylic acid and acrylamide, and poly AA/AMPS salt is copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid

The (AM/AMPS/AA) terpolymer is a copolymer of acrylic acid, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid; the polycarboxylic acid is a commercially available VIVID-500 polycarboxylic acid superplasticizer produced by Shanghai Sanrui high polymer materials GmbH, the water reducing rate of the polycarboxylic acid superplasticizer 1 is 25 percent, and the weight-average molecular weight is 43000; the water reducing rate of the polycarboxylic acid superplasticizer 2 is 29 percent, and the weight average molecular weight is 51000; the water reducing rate of the polycarboxylic acid superplasticizer 3 is 23 percent, and the weight average molecular weight is 48000.

Example 1

The hydroxypropyl xanthan gum powder is weighed according to the proportion, slowly added into water, stirred and dissolved, and then the other components are sequentially added to be fully dissolved.

Example 2

Firstly weighing hydroxypropyl xanthan gum and hydroxyethyl cellulose according to the proportion, slowly adding the hydroxypropyl xanthan gum and the hydroxyethyl cellulose into water, stirring and dissolving, and then sequentially adding other components to fully dissolve the hydroxypropyl xanthan gum and the hydroxyethyl cellulose.

Example 3

Firstly, weighing the poly (AA/AMPS) binary polymer according to the proportion, slowly adding the poly (AA/AMPS) binary polymer into water, stirring and dissolving, and then sequentially adding other components to fully dissolve the components.

Example 4

Firstly weighing the hydroxypropyl xanthan gum according to the proportion, slowly adding the hydroxypropyl xanthan gum into water, stirring and dissolving, and then sequentially adding other components to fully dissolve the hydroxypropyl xanthan gum.

Application example

The evaluation experiment of the admixture is carried out according to the mixture ratio in the table 1 by referring to the slump test method in GB/T50080-2016 Standard test method for the performance of common concrete mixture, and the result is shown in the table 2.

TABLE 1 reference mixing ratio of synchronous grouting slurry

Material	Sand	Fly ash	Bentonite clay	Lime	External mixing agent	Water (W)
							Mass/g	1180	300	50	80	3	285

TABLE 2 Performance of the simultaneous grouting slurries

As can be seen from Table 2, the slurry fluidity of examples 1 to 4 is better than that of the commercial competitive products at the same mixing amount, and the loss of fluidity of the commercial competitive products is large in the high calcium ash and the sea sand, while the admixture of the present invention has good fluidity in the high calcium ash and the fluidity in the sea sand is only slightly reduced. In addition, the bleeding rate of the slurry in examples 1 to 4 is less than 1.0%, the initial shear strength is greater than 300Pa, and the difference between the 20h slump and the initial slump is less than 5cm, so that the additive not only has good adaptability to materials, but also enables the slurry to have good long-term fluidity, and is an external additive for single-fluid synchronous grouting with excellent performance.

Claims

1. The admixture for shield single-fluid synchronous grouting is characterized by being prepared by mixing and stirring the following components in percentage by weight:

30 to 50% of polyacrylate,

0.5 to 10 percent of polycarboxylic acid superplasticizer,

1.0 to 5.0 percent of super-strong crystal nucleus early strength agent,

0.01 to 1.5 percent of bubble regulator,

0.01 to 1.5 percent of rheology regulator,

0.01 to 5 percent of retarder,

the balance of water;

the super-strong crystal nucleus early strength agent is a semitransparent calcium silicate gel solution prepared by a precipitation method, soluble calcium salt and sodium silicate are used as raw materials, the calcium-silicon ratio is 0.8-2.0, and the particle size is 50-350 nm;

the polyacrylate is a homopolymer of acrylic acid, or a binary or ternary copolymer of acrylic acid, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid, and the weight-average molecular weight of the polyacrylate is 10000-1000000;

the water reducing rate of the polycarboxylic acid superplasticizer is 20-30%, and the weight average molecular weight of the polycarboxylic acid superplasticizer is 10000-80000.

2. The admixture for single-fluid synchronous grouting of claim 1, wherein the rheology modifier is one or more of hydroxypropyl xanthan gum, maltodextrin, hydroxyethyl cellulose and guar gum.

3. The admixture for single-liquid synchronous grouting according to claim 1, wherein the bubble regulator is obtained by compounding an air-entraining agent and a defoaming agent, and the air-entraining agent is one or a mixture of sodium dodecyl sulfate, sodium cocoyl alanine, cocamidopropyl hydroxysultaine and sodium lauroyl sarcosinate; the defoaming agent is one or a mixture of more of an organic silicon defoaming agent and a modified polyether defoaming agent.

4. The admixture for single-fluid synchronous grouting according to claim 1, wherein the retarder is one or a mixture of calcium gluconate, sodium citrate and potassium tartrate.