Carbonizable shield soil base light fluid solidified soil and preparation method thereof

Abstract

The application provides a carbonizable shield soil base light fluid solidified soil and a preparation method thereof, and the preparation method comprises the following steps: adjusting the water content of shield soil to 1.9-2.2 times of the liquid limit of the shield soil to obtain shield mud; adding industrial solid wastes such as steel slag, carbide slag, blast furnace slag and cement into the shield mud to obtain an initial mixture; according to the leaching concentration of the surfactant in the shield soil, it is judged whether an air entraining agent needs to be added into the initial mixture; if yes, the air entraining agent, foam stabilizer and defoaming agent are dissolved in water to prepare carbon dioxide foam, and the carbon dioxide foam is added into the initial mixture to obtain the light fluid solidified soil; if no, the foam stabilizer is added into the initial mixture and stirred uniformly to obtain a first mixture, and carbon dioxide gas is uniformly blown into the first mixture to obtain the light fluid solidified soil; the light fluid solidified soil has a flow diameter greater than 16 cm and a density less than 1.35 g / cm 3 ; and the light fluid solidified soil is subjected to on-site pouring construction.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of civil engineering materials, and particularly relates to a carbonizable shield soil-based light fluidity solidified soil and a preparation method thereof. BACKGROUND

[0002] Shield soil refers to waste soil and rock fragments generated when a shield machine excavates underground space, and is usually treated by open-air stacking or landfill. However, the surfactant contained in the shield soil is difficult to dry, has great fluidity, and is prone to landslides when stacked in large quantities, which poses a safety hazard. Landfilling of the shield soil will lead to pollution of water bodies by the surfactant. Therefore, there is an urgent need to provide a method for harmless treatment of the shield soil.

[0003] Fluidity solidified soil is a new type of geotechnical engineering material, which is obtained by adding a solidifying agent and other additives to soil taken from the site and stirring the mixture to obtain a mixture with certain fluidity. After pouring or filling and curing, the mixture is solidified into a new type of engineering material with certain strength, water stability, low permeability and long-term stability. However, the main component of the solidifying agent is cement, which is a high-carbon emission material and is not conducive to environmental protection.

[0004] Therefore, how to provide a preparation method of a carbonizable shield soil-based light fluidity solidified soil, which uses shield soil and industrial solid waste as main components and prepares light fluidity solidified soil by injecting carbon dioxide, to meet the requirements of engineering trench backfill construction, is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0005] The present application aims to provide a carbonizable shield soil-based light fluidity solidified soil and a preparation method thereof, which at least solve the above technical problem.

[0006] To achieve the above object, the present application provides a preparation method of carbonizable shield soil-based light fluid solidified soil, which comprises the following steps: adjusting the water content of shield soil to 1.9-2.2 times of the liquid limit of the shield soil to obtain shield mud; adding industrial solid waste to the shield mud and stirring uniformly to obtain an initial mixture, wherein the addition amount of the industrial solid waste is 20-30% of the dry weight of the shield mud; judging whether an air entraining agent needs to be added to the initial mixture according to the leaching concentration of surfactant in the shield soil; when the leaching concentration is ≤20 mg / L, dissolving the air entraining agent, foam stabilizer and defoaming agent in water to prepare carbon dioxide foam, and adding the carbon dioxide foam to the initial mixture and stirring uniformly to obtain light fluid solidified soil; when the leaching concentration is >20 mg / L, adding foam stabilizer to the initial mixture and stirring uniformly to obtain a first mixture, and uniformly blowing carbon dioxide gas into the first mixture to obtain light fluid solidified soil; and performing on-site pouring construction on the light fluid solidified soil; wherein the flow diameter of the light fluid solidified soil is greater than 16 cm, and the density of the light fluid solidified soil is less than 1.35 g / cm 3 .

[0007] In the first aspect, the industrial solid waste comprises steel slag, carbide slag, blast furnace slag and cement, and the mass ratio of the steel slag, the carbide slag, the blast furnace slag and the cement is (3-4):(2-3):(2-3):(0-2).

[0008] In the first aspect, the dissolving of the air entraining agent, foam stabilizer and defoaming agent in water to prepare carbon dioxide foam comprises: weighing the air entraining agent, foam stabilizer and defoaming agent respectively and dissolving them in water to obtain a mixed solution; blowing carbon dioxide gas into the mixed solution through a bubble generator to obtain carbon dioxide foam, wherein the blowing pressure is 0.3-0.5 MPa; wherein the mass of the air entraining agent is 0.03-0.08% of the dry weight of the shield mud, the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the shield mud, and the mass of the defoaming agent is 0.01-0.03% of the dry weight of the shield mud.

[0009] In the first aspect, the volume of the carbon dioxide foam is 0-3% of the volume of the shield mud, and the diameter of the carbon dioxide foam is 100-200 μm.

[0010] In the first aspect, the adding of the foam stabilizer into the initial mixture, stirring to be uniform to obtain a first mixture, and uniformly blowing carbon dioxide gas into the first mixture include: weighing the foam stabilizer, the mass of the foam stabilizer being 0.03-0.08% of the dry weight of the shield slurry; adding the foam stabilizer into the initial mixture, stirring to be uniform to obtain a first mixture; and uniformly blowing carbon dioxide gas into the first mixture by a bubble generator, the diameter of the bubbles generated by the carbon dioxide gas being 100-200 microns, the blowing pressure of the gas being 0.5-0.7 MPa, and the volume of the gas blown being 3% of the volume of the shield slurry.

[0011] In the first aspect, after the in-situ pouring construction of the light fluidified solidified soil, the light fluidified solidified soil is covered by a plastic film or a non-woven geotextile, and is watered and maintained for 7 days.

[0012] The second aspect of the present application provides a carbonizable shield soil-based light fluidified solidified soil, which comprises the following components: shield slurry, industrial solid waste, air entraining agent, foam stabilizer, defoaming agent and carbon dioxide; the carbon dioxide is used to generate bubbles; the adding amount of the industrial solid waste is 20-30% of the dry weight of the shield slurry, the mass of the air entraining agent is 0.03-0.08% of the dry weight of the shield slurry, the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the shield slurry, and the mass of the defoaming agent is 0.01-0.03% of the dry weight of the shield slurry; wherein the flow diameter of the light fluidified solidified soil is greater than 16 cm, and the density of the light fluidified solidified soil is less than 1.35 g / cm 3 .

[0013] In the second aspect, the shield slurry is prepared by adjusting the water content of shield soil, and the water content of the shield slurry is 1.9-2.2 times of the liquid limit of the shield soil.

[0014] In the second aspect, the industrial solid waste comprises steel slag, carbide slag, blast furnace slag and cement, and the mass ratio of the steel slag, the carbide slag, the blast furnace slag and the cement is (3-4):(2-3):(2-3):(0-2).

[0015] In the second aspect, the air entraining agent comprises at least one of sodium fatty alcohol polyoxyethylene ether sulfate and sodium dodecyl benzene sulfonate; the foam stabilizer comprises at least one of silicone polyether emulsion, alkyl dimethyl amine oxide, alkyl alcohol amide, lauryl alcohol and lauryl diethanolamide; and the defoaming agent comprises one of polyvinyl alcohol and polyether alcohol.

[0016] Beneficial effects:

[0017] The application provides a preparation method of carbonizable shield soil base light fluid solidified soil, first, the water content of the shield soil is adjusted to 1.9-2.2 times of the liquid limit of the shield soil, and shield mud is obtained; second, industrial solid waste is added into the shield mud, and the addition amount of the industrial solid waste is adjusted to 20-30% of the dry weight of the shield mud, so that the industrial solid waste can be used as a solidifying agent to modify the shield mud and improve the comprehensive performance of the shield mud, thereby obtaining initial mixture; then, according to the concentration of the surfactant in the shield soil, it is judged whether an air entraining agent needs to be added into the initial mixture; the air entraining agent can improve the fluidity of the initial mixture, so that the initial mixture is easy to be stirred and mixed uniformly; when the air entraining agent needs to be added, the air entraining agent, a stabilizing agent and a defoaming agent are dissolved in water to prepare carbon dioxide foam, and the carbon dioxide foam is added into the initial mixture and stirred uniformly to obtain light fluid solidified soil; the carbon dioxide foam can not only solidify harmful substances in the shield mud and the industrial waste, but also control the size of the bubbles in the reaction process; when the air entraining agent does not need to be added, a foam stabilizer is added into the initial mixture, and after being stirred uniformly, a first mixture is obtained, and carbon dioxide gas is uniformly generated in the first mixture to obtain light fluid solidified soil; the foam stabilizer can control the size of the bubbles generated by the carbon dioxide gas in the mixture, and the generated carbonate can solidify harmful substances in the shield mud and the industrial waste; finally, the light fluid solidified soil has a flow diameter greater than 16 cm and a density less than 1.35 g / cm 3 The light fluid solidified soil can be used for on-site pouring construction, can be used for backfilling of engineering trenches as solidified soil, and can be used as building materials.

[0018] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, the application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the following will specifically describe the embodiments of the application. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical scheme in the embodiments or prior art of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0020] Figure 1 Flow chart of the preparation method of a carbonizable shield soil-based light fluidized solidified soil in the present application. DETAILED DESCRIPTION

[0021] The advantages and various effects of the present application will be more clearly presented hereinafter in conjunction with specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, rather than limit the present application.

[0022] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. If there is a contradiction, the present specification takes precedence.

[0023] Unless otherwise specifically indicated, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or obtained by existing methods.

[0024] The general idea of the present application is as follows:

[0025] The shield soil not only contains a surfactant, but also contains a foaming agent. When the light fluidized solidified soil is prepared by using the shield soil as a raw material, not only the addition amount of the air entraining agent, the foam stabilizer and the defoaming agent can be reduced, but also the shield soil can be "waste to treasure", realizing the resource utilization of the shield soil. Among them, the main components of the foaming agent include a foaming component, a foam stabilizing component and a functional component; the foaming component is the main component of the foaming agent, responsible for generating foam, and its quality and ratio directly affect the foam production and stability of the foaming agent; the foam stabilizing component is responsible for increasing the stability and durability of the foam, preventing premature decomposition or failure during use; the functional component is added according to specific needs, such as preservatives, antifreeze agents, etc., to improve the overall performance of the foaming agent.

[0026] In addition, by mixing carbon dioxide bubbles into the fluidized solidified soil, not only can the light fluidized solidified soil be formed to have lighter density and better fluidity, reduce the load on the underlying foundation structure, and improve the sealing effect, but also the cementing effect can be strengthened, realizing carbon utilization and carbon sequestration.

[0027] Based on this, the present application proposes a light fluidized solidified soil prepared by using the shield soil and the industrial solid waste as main components and injecting carbon dioxide, so as to meet the requirements of the engineering trench backfill construction.

[0028] Please refer to Figure 1The application provides a preparation method of a carbonizable shield soil-based light fluid solidified soil, and the preparation method comprises the following steps: adjusting the water content of shield soil to 1.9-2.2 times of the liquid limit of the shield soil to obtain shield mud; adding industrial solid waste into the shield mud and stirring uniformly to obtain an initial mixture, and the addition amount of the industrial solid waste is 20-30% of the dry weight of the shield mud; judging whether an air entraining agent needs to be added into the initial mixture according to the concentration of a surfactant in the shield soil; when the leaching concentration is less than or equal to 20 mg / L, dissolving the air entraining agent, a foam stabilizer and a defoaming agent in water to prepare carbon dioxide foam, and adding the carbon dioxide foam into the initial mixture and stirring uniformly to obtain the light fluid solidified soil; when the leaching concentration is greater than 20 mg / L, adding the foam stabilizer into the initial mixture and stirring uniformly to obtain a first mixture, and uniformly blasting carbon dioxide gas into the first mixture to obtain the light fluid solidified soil; and pouring and constructing the light fluid solidified soil on site, wherein the flow diameter of the light fluid solidified soil is greater than 16 cm, and the density of the light fluid solidified soil is less than 1.35 g / cm 3 .

[0029] Specifically, the preparation method of the carbonizable shield soil-based light fluid solidified soil provided by the application firstly adjusts the water content of shield soil to 1.9-2.2 times of the liquid limit of the shield soil to obtain shield mud; secondly, industrial solid waste is added into the shield mud, and the addition amount of the industrial solid waste is adjusted to 20-30% of the dry weight of the shield mud, so that the industrial solid waste can be used as a solidifying agent to modify the shield mud and improve the comprehensive performance of the shield mud, thereby obtaining an initial mixture; then, whether an air entraining agent needs to be added into the initial mixture is judged according to the concentration of a surfactant in the shield soil, the flowability of the initial mixture can be improved by the air entraining agent, so that the initial mixture is easy to stir and mix uniformly; when the air entraining agent needs to be added, the air entraining agent, a stabilizer and a defoaming agent are dissolved in water to prepare carbon dioxide foam, and the carbon dioxide foam is added into the initial mixture and stirred uniformly to obtain the light fluid solidified soil, the carbon dioxide foam can not only solidify harmful substances in the shield mud and the industrial waste, but also control the size of the bubble diameter in the reaction process; when the air entraining agent does not need to be added, a foam stabilizer is added into the initial mixture and stirred uniformly to obtain a first mixture, and carbon dioxide gas is uniformly blasted into the first mixture to obtain the light fluid solidified soil, the foam stabilizer added in advance can control the diameter of the bubbles generated by the carbon dioxide gas in the mixture, and the generated carbonate can solidify harmful substances in the shield mud and the industrial waste; finally, the flow diameter of the obtained light fluid solidified soil is greater than 16 cm, and the density of the light fluid solidified soil is less than 1.35 g / cm 3The light fluid solidified soil is solidified on site, can be used for backfilling of the solidified soil in the engineering trench, and can be used as a building material. The light fluid solidified soil with excellent performance is prepared by injecting carbon dioxide into shield mud and industrial solid waste, and adjusting the bubble diameter size in the reaction process by combining the surfactant or air entraining agent, foam stabilizer and defoaming agent in the shield mud, and the difficult-to-handle surfactant in the shield mud is efficiently utilized, the treatment process of the shield mud is reduced, and the utilization efficiency of the shield mud is improved.

[0030] It should be noted that, in the present application, the shield soil includes shield mud, shield dry soil and shield slag soil, the shield mud is at the bottom of a sedimentation tank in a shield construction site or a slag soil treatment plant, the shield dry soil is dry soil treated by screening and dewatering in the shield construction site or the slag soil treatment plant, and the shield slag soil is shield slag soil with a sand content of less than 50% and without screening treatment generated during earth pressure balance construction.

[0031] In some possible embodiments, the industrial solid waste includes steel slag, carbide slag, blast furnace slag and cement, and the mass ratio of the steel slag, the carbide slag, the blast furnace slag and the cement is (3-4):(2-3):(2-3):(0-2).

[0032] As can be understood by those skilled in the art, the steel slag, the carbide slag, the blast furnace slag and the cement are used as the solidifying agent in the present embodiment, the performance of the shield mud can be improved, and the industrial solid waste is consumed, thereby realizing the recycling of waste resources. The content of metal oxides such as calcium and magnesium in the steel slag and the carbide slag is relatively high, can form stable carbonates with carbon dioxide, and thereby solidify harmful substances in the shield mud; the blast furnace slag and the cement have relatively high pozzolanic activity, can react with calcium oxide to generate hydrates with hydraulic cementitious properties, and thereby improve the strength of the solidified soil body. In specific embodiments, the cement can not be used, and the carbon emission in the production process is reduced.

[0033] In some possible embodiments, the dissolving of the air entraining agent, the foam stabilizer and the defoaming agent in water to prepare carbon dioxide foam includes: respectively weighing the air entraining agent, the foam stabilizer and the defoaming agent, and dissolving them in water to obtain a mixed solution; and injecting carbon dioxide gas into the mixed solution through a bubble generator, the gas explosion pressure is 0.3-0.5 MPa, and the carbon dioxide foam is obtained; wherein the mass of the air entraining agent is 0.03-0.08% of the dry weight of the shield mud, the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the shield mud, and the mass of the defoaming agent is 0.01-0.03% of the dry weight of the shield mud.

[0034] In some possible embodiments, the volume of the carbon dioxide foam is 0-3% of the volume of the shield slurry; and the diameter of the carbon dioxide foam is 100-200 microns.

[0035] This is because the air entraining agent can improve the workability, water retention and cohesiveness of the slurry mixture by introducing a large number of micro-bubbles, improve the fluidity, frost resistance and durability of the slurry mixture; the foam stabilizer can prevent the bubbles formed by the air entraining agent and carbon dioxide from breaking; and the defoaming agent can convert large bubbles into small bubbles, so that the bubble size is uniform, which is conducive to the progress of the reaction.

[0036] In some possible embodiments, the adding the foam stabilizer to the initial mixture and stirring uniformly to obtain a first mixture, and uniformly blasting carbon dioxide gas into the first mixture comprises: weighing the foam stabilizer, the mass of the foam stabilizer being 0.03-0.08% of the dry weight of the shield slurry; adding the foam stabilizer to the initial mixture and stirring uniformly to obtain a first mixture; and uniformly blasting carbon dioxide gas into the first mixture by a bubble generator, the diameter of the bubbles generated by the carbon dioxide gas being 100-200 microns, the blasting pressure being 0.5-0.7 MPa, and the volume of the blasting gas being 3% of the volume of the shield slurry.

[0037] Those skilled in the art can understand that when the surfactant is contained in the shield slurry, the surfactant can be used as the air entraining agent, and the foam stabilizer is added at the same time, so that the bubbles generated by the injected carbon dioxide are in the range of 100-200 microns, the surfactant which is difficult to handle in the shield slurry is efficiently utilized, and the recycling of resources is realized.

[0038] In some possible embodiments, after the in-situ pouring construction of the light fluidified solidified soil, the light fluidified solidified soil is covered by a plastic film or a non-woven geotextile and is watered and maintained for 7 days.

[0039] Since the light fluidified solidified soil is a new type of engineering material, has certain strength, water stability, low permeability and durability, and is used as a soil material to backfill a trench, the construction method is simple and easy to operate.

[0040] Based on a general inventive concept, the second aspect of the present application provides a carbonizable shield soil-based light fluidified solidified soil, which comprises the following components: shield slurry, industrial solid waste, air entraining agent, foam stabilizer, defoaming agent and carbon dioxide; the carbon dioxide is used to generate bubbles; the addition amount of the industrial solid waste is 20-30% of the dry weight of the shield slurry, the mass of the air entraining agent is 0.03-0.08% of the dry weight of the shield slurry, the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the shield slurry, and the mass of the defoaming agent is 0.01-0.03% of the dry weight of the shield slurry; wherein the flow diameter of the light fluidified solidified soil is greater than 16 cm, and the density of the light fluidified solidified soil is less than 1.35 g / cm 3 .

[0041] Specifically, the carbonizable shield soil-based light fluidified solidified soil provided by the present application comprises the following components: shield slurry, industrial solid waste, air entraining agent, foam stabilizer, defoaming agent and carbon dioxide. The shield slurry is used as the main component of the light fluidified solidified soil, and the industrial solid waste is used as a solidifying agent. The strength of the shield slurry is improved by the industrial solid waste, and the diameter of the bubbles generated by the carbon dioxide is controlled by the air entraining agent, the foam stabilizer and the defoaming agent. Thus, a reaction site is provided for the carbon dioxide to form carbonates with calcium and magnesium in the shield slurry and the industrial solid waste, so as to solidify the harmful substances. Further, the surfactant in the shield slurry can be fully utilized as the air entraining agent, the addition of raw materials is reduced, and the processing procedure of the shield slurry is reduced. The carbon dioxide is used as a bubble generating component, which can effectively solidify the harmful substances in the shield slurry. The industrial solid waste is used as a solidifying agent, which can improve the strength of the solidified soil, realize the recycling of waste resources, and effectively reduce carbon emissions.

[0042] In combination with the second aspect of the present application, the shield slurry is prepared by adjusting the water content of the shield soil, and the water content of the shield slurry is 1.9-2.2 times the liquid limit of the shield soil.

[0043] Those skilled in the art can understand that by controlling the water content of the shield slurry to be 1.9-2.2 times the liquid limit of the shield soil, the reaction progress can be adjusted, so as to adjust the flow diameter and the density of the light fluidified solidified soil.

[0044] In combination with the second aspect of the present application, the industrial solid waste comprises steel slag, carbide slag, blast furnace slag and cement, and the mass ratio of the steel slag, the carbide slag, the blast furnace slag and the cement is (3-4):(2-3):(2-3):(0-2).

[0045] In combination with the second aspect of the present application, the air entraining agent includes at least one of sodium fatty alcohol ether sulfate and sodium dodecyl benzene sulfonate; the foam stabilizer includes at least one of silicone polyether emulsion, alkyl dimethyl amine oxide, alkyl alcohol amide, lauryl alcohol and lauryl diethanolamide; and the defoaming agent includes one of polyvinyl alcohol and polyether alcohol.

[0046] In specific embodiments, sodium fatty alcohol ether sulfate is selected as the air entraining agent, which has strong wetting and dispersing properties and abundant foaming power, and is suitable for scenarios requiring a large amount of foam. When used as an air entraining agent in solidified soil, it can improve the water retention and cohesiveness during raw material mixing, and improve the durability and frost resistance of the solidified soil. The foam stabilizer can improve the viscosity of the foam and reduce the stress under external force, thereby making the foam more uniform and fine. The defoaming agent has excellent defoaming ability, is chemically stable, and is highly safe. In addition, since shield mud is generated by a shield machine during excavation of underground space, a surfactant may be added during excavation to improve the excavation efficiency. Therefore, the shield mud may contain untreated surfactant. In specific embodiments, the operator can supplement the corresponding air entraining agent, foam stabilizer and defoaming agent according to the type of surfactant in the shield mud.

[0047] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods in the following examples are not specified, and generally follow the national standards. If there is no corresponding national standard, the general international standard, conventional conditions, or the conditions recommended by the manufacturer are followed.

[0048] Example 1

[0049] In this embodiment, the shield soil is a dried mud cake obtained by dehydration treatment at a shield construction site, and the leaching concentration of the surfactant is 362 mg / L. The detection method of the leaching concentration of the surfactant is as follows: the dried mud cake and water are leached at a solid-liquid ratio of 1:10, and then the concentration of the surfactant in the leaching solution is detected. The preparation method of the carbonizable shield soil-based light fluidized solidified soil prepared in this way specifically includes the following steps:

[0050] (1) The water content of the shield soil is adjusted to 2 times the liquid limit to obtain shield mud;

[0051] (2) Steel slag, carbide slag and blast furnace slag are selected as industrial solid waste at a mass ratio of 4:3:3, and the industrial solid waste is added to the shield mud, and the addition amount of the industrial solid waste is 30% of the dry weight of the shield mud, and the mixture is stirred uniformly to obtain an initial mixture;

[0052] (3) adding a foam stabilizer to the initial mixture, the mass of the foam stabilizer being 0.03% of the dry weight of the shield mud, and stirring uniformly to obtain a first mixture;

[0053] (4) uniformly exploding carbon dioxide gas into the first mixture through a bubble generator, the explosion pressure being 0.7 MPa, the explosion volume being 3% of the volume of the shield mud, the diameter of the bubbles generated by the carbon dioxide gas being 100-200 μm, and the density of the light fluidized solidified soil being 1.28 g / cm 3 , the flow diameter being 18 cm;

[0054] (5) pouring the light fluidized solidified soil into a trench for on-site pouring, and immediately covering with a plastic film or a non-woven geotextile after pouring is completed, and maintaining moisture by watering for 7 days.

[0055] It is detected that the carbon dioxide utilization rate is 75%, and the strength of the material soil body after 28 days is 0.67 MPa.

[0056] Example 2

[0057] The shield soil selected in this example is a dried mud cake after dehydration treatment at a shield construction site, and the leaching concentration of the surfactant is 127 mg / L. The method for detecting the leaching concentration of the surfactant is as follows: after the dried mud cake and water are leached at a solid-liquid ratio of 1:10, the concentration of the surfactant in the leaching liquid is detected. The method for preparing the carbonizable shield soil-based light fluidized solidified soil prepared in this way specifically includes the following steps:

[0058] (1) adjusting the water content of the shield soil to 2 times the liquid limit to obtain shield mud;

[0059] (2) selecting steel slag, carbide slag, blast furnace slag and cement with a mass ratio of 4:3:3:2 as industrial solid waste, adding the industrial solid waste to the shield mud, the addition amount of the industrial solid waste being 30% of the dry weight of the shield mud, and stirring uniformly to obtain an initial mixture;

[0060] (3) adding a foam stabilizer to the initial mixture, the mass of the foam stabilizer being 0.05% of the dry weight of the shield mud, and stirring uniformly to obtain a first mixture;

[0061] (4) uniformly exploding carbon dioxide gas into the first mixture through a bubble generator, the explosion pressure being 0.5-0.7 MPa, the explosion volume being 3% of the volume of the shield mud, the diameter of the bubbles generated by the carbon dioxide gas being 100-200 μm, and the second mixture having a flow diameter of not less than 16 cm and a density higher than 1.35 g / cm 3 ;

[0062] (5) preparing carbon dioxide foam, dissolving air entraining agent, foam stabilizer and defoaming agent in water to obtain a mixed solution, the mass of the air entraining agent is 0.03% of the dry weight of the shield mud, the mass of the foam stabilizer is 0.03% of the dry weight of the shield mud, and the mass of the defoaming agent is 0.01% of the dry weight of the shield mud; carbon dioxide gas is exploded into the mixed solution through a bubble generator, the explosion pressure is 0.3 MPa, and the carbon dioxide foam is obtained, the diameter of the carbon dioxide foam is 100-200 μm;

[0063] The carbon dioxide foam is added into the second mixture, the volume of the carbon dioxide foam is 1% of the volume of the shield mud, and the mixture is stirred uniformly, so that the light-weight fluidified solidified soil with a density of 1.2 g / cm 3 , a flow diameter of 18.5 cm is obtained.

[0064] (6) The light-weight fluidified solidified soil is poured into a trench for on-site pouring, and immediately after pouring, the light-weight fluidified solidified soil is covered with a plastic film or a non-woven geotextile and is watered and maintained for 7 days.

[0065] It is detected that the carbon dioxide utilization rate is 70%, and the strength of the material soil body after 28 days is 0.64 MPa.

[0066] Example 3

[0067] The shield soil selected in the embodiment is a dried mud cake after dehydration treatment on a shield construction site, and the leaching concentration of the surface activity is less than 20 mg / L. The preparation method of the carbonizable shield soil-based light-weight fluidified solidified soil specifically includes the following steps:

[0068] (1) The water content of the shield soil is adjusted to 2 times the liquid limit, and a shield mud is obtained.

[0069] (2) Steel slag, carbide slag, blast furnace slag and cement with a mass ratio of 4:3:3:2 are selected as industrial solid wastes, and the industrial solid wastes are added into the shield mud, and the addition amount of the industrial solid wastes is 20% of the dry weight of the shield mud, and the mixture is stirred uniformly, so that an initial mixture is obtained.

[0070] (3) Carbon dioxide foam is prepared, air entraining agent, foam stabilizer and defoaming agent are dissolved in water to obtain a mixed solution, the mass of the air entraining agent is 0.08% of the dry weight of the shield mud, the mass of the foam stabilizer is 0.08% of the dry weight of the shield mud, and the mass of the defoaming agent is 0.03% of the dry weight of the shield mud; carbon dioxide gas is exploded into the mixed solution through a bubble generator, the explosion pressure is 0.7 MPa, and the carbon dioxide foam is obtained, the diameter of the carbon dioxide foam is 100-200 μm;

[0071] (4) The carbon dioxide foam is added into the initial mixture, the volume of the carbon dioxide foam is 3% of the volume of the shield mud, and the mixture is stirred uniformly, so that the light-weight fluidified solidified soil with a density of 1.26 g / cm 3lightweight fluidified stabilized soil with a flow diameter of 19 cm;

[0072] (5) The lightweight fluidified stabilized soil is injected into the trench for in-situ pouring. After pouring, the soil is immediately covered with plastic film or non-woven geotextile and watered for 7 days for curing.

[0073] The carbon dioxide utilization rate is 73%, and the soil strength of the material after 28 days is 0.57 MPa.

[0074] Comparative Example 1

[0075] In this comparative example, step (3) is omitted compared with Example 1, and the rest of the steps remain unchanged. The density of the obtained lightweight fluidified stabilized soil is 1.46 g / cm 3 . This is because, without the addition of a foam stabilizer, the bubbles in the initial mixture are easily broken, causing carbon dioxide gas to overflow, and the density of the obtained stabilized soil increases.

[0076] Comparative Example 2

[0077] In this comparative example, the amount of industrial solid waste added is 40% of the dry weight of the shield slurry compared with Example 1, and the rest of the steps remain unchanged. The flow diameter of the obtained lightweight fluidified stabilized soil is 16 cm. This is because the addition of industrial solid waste is relatively large, the hydration reaction is more intense, and the consistency of the initial mixture is larger, resulting in a decrease in the flow diameter of the stabilized soil.

[0078] Comparative Example 3

[0079] In this comparative example, the amount of industrial solid waste added is 10% of the dry weight of the shield slurry compared with Example 1, and the rest of the steps remain unchanged. The soil strength of the obtained lightweight fluidified stabilized soil after 28 days is 0.28 MPa. This is because the amount of industrial solid waste added is relatively small, the hydration products and carbonation products are less, and the cementation effect is weakened, resulting in a decrease in the soil strength of the stabilized soil after pouring.

[0080] Comparative Example 4

[0081] In this comparative example, steel slag and calcium carbide slag with a mass ratio of 4:3 are selected as industrial solid waste compared with Example 1, and the rest of the steps remain unchanged. The soil strength of the obtained lightweight fluidified stabilized soil after 28 days is 0.21 MPa. This is because, as a blast furnace slag and cement containing pozzolanic activity, they are not added in this comparative example, resulting in almost no hydration products and only a small amount of carbonation products, and the cementation effect is weakened, resulting in a decrease in the soil strength of the stabilized soil after pouring.

[0082] Comparative Example 5

[0083] In the present comparative example, compared with example 1, the carbide slag and blast furnace slag with a mass ratio of 3:3 are selected as the industrial solid waste, and the remaining steps are unchanged. It is detected that the utilization rate of carbon dioxide is 38%. This is because, in the present comparative example, only the carbide slag and blast furnace slag are added, and the content of metal oxides such as calcium and magnesium is low, resulting in a low utilization rate of carbon dioxide.

[0084] Comparative example 6

[0085] In the present comparative example, compared with example 1, the water content of the shield soil is adjusted to 1.8 times the liquid limit, and the remaining steps are unchanged. The flow diameter of the lightweight fluidified solidified soil obtained is 15 cm. This is because the water content of the shield mud is low, resulting in a high concentration of industrial solid waste in the initial mixture, a violent hydration reaction, and a large consistency of the initial mixture, thereby reducing the flow diameter of the solidified soil.

[0086] Comparative example 7

[0087] In the present comparative example, compared with example 1, the water content of the shield soil is adjusted to 2.3 times the liquid limit, and the remaining steps are unchanged. The strength of the soil body of the lightweight fluidified solidified soil obtained is 0.27 MPa after pouring is completed. This is because the high water content of the shield mud results in a low density of the solidified soil, thereby reducing the strength of the solidified soil after pouring.

[0088] In summary, compared with the prior art, the present application has the following advantages:

[0089] (1) The present application uses carbon dioxide gas, which not only solidifies the harmful substances in the shield mud, but also reduces carbon emissions during production;

[0090] (2) The present application uses industrial solid waste such as steel slag, carbide slag, blast furnace slag and cement as a solidifying agent to modify the shield mud, and obtains a lightweight fluidified solidified soil with excellent performance, thereby realizing the recycling of waste resources;

[0091] (3) The present application can fully utilize the untreated surfactant in the shield mud, thereby reducing the treatment process of the shield mud and realizing the harmless treatment of the shield mud.

[0092] Finally, it should be noted that the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or equipment.

[0093] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims include all such modifications and variations as fall within the scope of the present application.

[0094] It is apparent that those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. It is therefore intended that the present application cover all such changes and modifications that are within its scope.

Claims

1. A method for preparing a carbonizable lightweight fluidized solidified soil for shield tunneling, characterized in that, The preparation method includes the following steps: Adjust the moisture content of the shield soil to 1.9-2.2 times its liquid limit to obtain shield slurry; Industrial solid waste is added to the shield tunneling mud and stirred evenly to obtain an initial mixture. The amount of industrial solid waste added is 20-30% of the dry weight of the shield tunneling mud. Based on the leaching concentration of surfactant in the shield soil, determine whether it is necessary to add an air-entraining agent to the initial mixture; When the leaching concentration is ≤20mg / L, the air-entraining agent, foam stabilizer and defoamer are dissolved in water to prepare carbon dioxide foam, and the carbon dioxide foam is added to the initial mixture and stirred evenly to obtain lightweight fluidized solidified soil; When the leaching concentration is >20mg / L, a foam stabilizer is added to the initial mixture, and the mixture is stirred evenly to obtain a first mixture. Carbon dioxide gas is then uniformly released into the first mixture to obtain lightweight fluidized solidified soil. The lightweight fluidized solidified soil was poured on-site. The lightweight fluidized solidified soil has a flow diameter greater than 16 cm and a density less than 1.35 g / cm³. 3 ; The industrial solid waste includes steel slag, carbide slag, blast furnace slag and cement, and the mass ratio of the steel slag, carbide slag, blast furnace slag and cement is (3-4):(2-3):(2-3):(0-2).

2. The method for preparing carbonizable shield tunnel foundation lightweight fluidized solidified soil according to claim 1, characterized in that, The step of dissolving the air-entraining agent, foam stabilizer, and defoamer in water to prepare carbon dioxide foam includes: Weigh out the air-entraining agent, foam stabilizer, and defoamer separately, and dissolve them in water to obtain a mixture; Carbon dioxide gas is introduced into the mixture using a bubble generator at a pressure of 0.3-0.5 MPa to obtain carbon dioxide foam. The mass of the air-entraining agent is 0.03-0.08% of the dry weight of the shield tunneling mud, the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the shield tunneling mud, and the mass of the defoamer is 0.01-0.03% of the dry weight of the shield tunneling mud.

3. The method for preparing carbonizable shield tunnel foundation lightweight fluidized solidified soil according to claim 1 or 2, characterized in that, The volume of the carbon dioxide foam is 0-3% of the volume of the shield tunneling mud; the diameter of the carbon dioxide foam is 100-200μm; wherein the volume of the carbon dioxide foam is not zero.

4. The method for preparing carbonizable lightweight fluidized solidified soil for shield tunneling according to claim 1, characterized in that, The step of adding a foam stabilizer to the initial mixture, stirring evenly to obtain a first mixture, and uniformly releasing carbon dioxide gas into the first mixture includes: Weigh out the foam stabilizer, the mass of which is 0.03-0.08% of the dry weight of the tunnel boring machine slurry; Add the foam stabilizer to the initial mixture and stir until homogeneous to obtain the first mixture; Carbon dioxide gas is uniformly atomized into the first mixture using a bubble generator, and the diameter of the carbon dioxide gas bubbles is 100-200μm, the atomization pressure is 0.5-0.7MPa, and the atomization volume is 3% of the volume of the shield tunneling mud.

5. The method for preparing carbonizable shield tunnel foundation lightweight fluidized solidified soil according to claim 1, characterized in that, After the on-site pouring of the lightweight fluidized solidified soil, the method further includes: After the lightweight fluidized solidified soil is poured, it is covered with plastic film or non-woven geotextile and moisturized with water for 7 days.

6. A carbonizable lightweight fluidized solidified soil for shield tunneling, characterized in that, The lightweight fluidized solidified soil comprises the following components: tunnel boring machine slurry, industrial solid waste, air-entraining agent, foam stabilizer, defoamer, and carbon dioxide; the carbon dioxide is used to generate bubbles; the amount of industrial solid waste added is 20-30% of the dry weight of the tunnel boring machine slurry, the mass of the air-entraining agent is 0.03-0.08% of the dry weight of the tunnel boring machine slurry, the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the tunnel boring machine slurry, and the mass of the defoamer is 0.01-0.03% of the dry weight of the tunnel boring machine slurry. The lightweight fluidized solidified soil has a flow diameter greater than 16 cm and a density less than 1.35 g / cm³. 3 ; The shield tunneling mud is made by adjusting the moisture content of the shield soil, and the moisture content of the shield tunneling mud is 1.9-2.2 times the liquid limit of the shield soil; The industrial solid waste includes steel slag, carbide slag, blast furnace slag and cement, and the mass ratio of the steel slag, carbide slag, blast furnace slag and cement is (3-4):(2-3):(2-3):(0-2).

7. The carbonizable lightweight fluidized solidified soil for shield tunneling as described in claim 6, characterized in that, The air-entraining agent includes at least one of sodium fatty alcohol polyoxyethylene ether sulfate and sodium dodecylbenzene sulfonate; the foam stabilizer includes at least one of silicone polyether emulsion, alkyl dimethyl amine oxide, alkyl alcohol amide, lauryl alcohol, and lauroyl diethanolamine; and the defoamer includes one of polyvinyl alcohol and polyether alcohol.

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