Carbonizable shield soil-based light flow-state solidified soil and preparation method of carbonizable shield soil-based light flow-state solidified soil

Abstract

The invention provides carbonizable shield soil base light flow state solidified soil and a preparation method thereof.The preparation method comprises the following steps that the water content of shield soil is adjusted to be 1.9-2.2 times of the liquid limit of the shield soil, and shield slurry is obtained; adding industrial solid wastes such as steel slag, carbide slag, blast furnace slag and cement into the shield slurry to obtain an initial mixture; according to the leaching concentration of the surfactant in the shield soil, whether an air entraining agent needs to be added into the initial mixture or not is judged; if yes, an air entraining agent, a foam stabilizer and a defoaming agent are dissolved in water to prepare carbon dioxide foam, the carbon dioxide foam is added into the initial mixture, and light flow-state solidified soil is obtained; if not, adding a foam stabilizer into the initial mixture, uniformly stirring to obtain a first mixture, and uniformly exploding carbon dioxide gas into the first mixture to obtain light flow-state solidified soil; the flow diameter of the light flow state solidified soil is larger than 16 cm, and the density is smaller than 1.35 g / cm < 3 >; and carrying out cast-in-place construction on the light flow-state solidified soil.

Description

Technical Field

[0001] The present invention belongs to the technical field of civil engineering materials, and particularly relates to a carbonizable shield soil-based lightweight fluidized solidified soil and a preparation method thereof. Background Art

[0002] Shield soil refers to the waste soil and rock fragments generated when a shield machine excavates underground space. Usually, it is disposed of by open-air stacking or landfill. However, the surfactant contained in shield soil is difficult to dry in the sun, has high fluidity, and there are potential safety hazards such as landslides when a large amount is piled up; landfill will cause surfactant to pollute water bodies. Therefore, there is an urgent need to provide a method for harmless treatment of shield soil.

[0003] Fluidized solidified soil is a new type of geotechnical engineering material. It can be obtained by taking soil on-site, adding a curing agent and other additives, and stirring to obtain a mixture with a certain fluidity. After pouring, filling, and curing, it solidifies into a new type of engineering material with certain strength, water stability, low permeability, and long-term stability. However, the main component of the curing agent is mostly 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 lightweight fluidized solidified soil, using shield soil and industrial solid waste as the main components, and preparing lightweight fluidized solidified soil by injecting carbon dioxide to meet the requirements of engineering trench backfill construction is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a carbonizable shield soil-based lightweight fluidized solidified soil and a preparation method thereof to solve at least one of the above technical problems.

[0006] To achieve the above object, the first aspect of the present invention provides a preparation method of a carbonizable shield soil-based lightweight fluidized solidified soil. The preparation method includes the following steps: adjusting the water content of the shield soil to 1.9 - 2.2 times the liquid limit of the shield soil to obtain shield mud; adding industrial solid waste to the shield mud and stirring evenly to obtain an initial mixture, where the addition amount of the industrial solid waste is 20 - 30% of the dry weight of the shield mud; judging whether it is necessary to add an air-entraining agent to the initial mixture according to the leaching concentration of the surfactant in the shield soil; when the leaching concentration ≤ 20mg / 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 evenly to obtain lightweight fluidized solidified soil; when the leaching concentration > 20mg / L, adding a foam stabilizer to the initial mixture, stirring evenly to obtain a first mixture, and uniformly injecting carbon dioxide gas into the first mixture to obtain lightweight fluidized solidified soil; performing on-site pouring construction on the lightweight fluidized solidified soil; wherein, the flow diameter of the lightweight fluidized solidified soil is greater than 16cm, and the density of the lightweight fluidized solidified soil is less than 1.35g / cm 3 .

[0007] In the first aspect, 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).

[0008] In the first aspect, the preparation of carbon dioxide foam by dissolving the air-entraining agent, foam stabilizer and defoaming agent in water includes: respectively weighing the air-entraining agent, foam stabilizer and defoaming agent, and dissolving them in water to obtain a mixed solution; injecting carbon dioxide gas into the mixed solution through a bubble generator, and the aeration pressure is 0.3 - 0.5MPa to obtain carbon dioxide foam; 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; the diameter of the carbon dioxide foam is 100 - 200μm.

[0010] In the first aspect, adding a foam stabilizer to the initial mixture, stirring evenly to obtain a first mixture, and uniformly injecting carbon dioxide gas into the first mixture includes: weighing the foam stabilizer, where the mass of the foam stabilizer is 0.03-0.08% of the dry weight of the shield mud; adding the foam stabilizer to the initial mixture and stirring evenly to obtain a first mixture; uniformly injecting carbon dioxide gas into the first mixture through a bubble generator, and the bubble diameter generated by the carbon dioxide gas is 100-200 μm, the gas injection pressure is 0.5-0.7 MPa, and the gas injection volume is 3% of the volume of the shield mud.

[0011] In the first aspect, after the on-site pouring construction of the lightweight flowable solidified soil, it further includes: after the lightweight flowable solidified soil is poured, covering it with a plastic film or non-woven geotextile and spraying water for moisture conservation for 7 days.

[0012] The second aspect of the present invention provides a carbonizable lightweight flowable solidified soil for shield soil foundation, and the lightweight flowable solidified soil includes the following components: shield mud, 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 mud, 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; wherein, the flow diameter of the lightweight flowable solidified soil is greater than 16 cm, and the density of the lightweight flowable solidified soil is less than 1.35 g / cm 3 。

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

[0014] In the second aspect, 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).

[0015] In the second aspect, the air-entraining agent includes at least one of sodium lauryl polyoxyethylene ether sulfate and sodium dodecylbenzenesulfonate; the foam stabilizer includes at least one of silicone resin polyether emulsion, alkyl dimethyl amine oxide, alkyl alkanolamide, lauryl alcohol, and lauroyl diethanolamine; the defoaming agent includes one of polyvinyl alcohol and polyether alcohol.

[0016] Beneficial effects:

[0017] A preparation method of carbonizable shield soil-based lightweight fluidized solidified soil provided by the present invention. First, adjust the moisture content of the shield soil to 1.9 - 2.2 times the liquid limit of the shield soil to obtain shield slurry. Second, add industrial solid waste to the shield slurry and adjust the addition amount of the industrial solid waste to 20 - 30% of the dry weight of the shield slurry, so that the industrial solid waste can be used as a curing agent to modify the shield slurry and improve the comprehensive performance of the shield slurry, thereby obtaining an initial mixture. Then, according to the concentration of the surfactant in the shield soil, determine whether it is necessary to add an air-entraining agent to the initial mixture. The air-entraining agent can improve the fluidity of the initial mixture and make it easy to be stirred and mixed evenly. When an air-entraining agent needs to be added, dissolve the air-entraining agent, stabilizer and defoaming agent in water to prepare carbon dioxide foam, and add the carbon dioxide foam to the initial mixture and stir evenly to obtain lightweight fluidized solidified soil. The carbon dioxide foam can not only solidify the harmful substances in the shield slurry and industrial waste, but also control the size of the bubble diameter during the reaction process. When an air-entraining agent does not need to be added, add a foam stabilizer to the initial mixture, stir evenly to obtain a first mixture, and uniformly explode carbon dioxide gas into the first mixture to obtain lightweight fluidized solidified soil. The pre-added foam stabilizer can control the diameter of the bubbles generated by the carbon dioxide gas in the mixture, and at the same time, the generated carbonate can solidify the harmful substances in the shield slurry and industrial waste. Finally, the flow diameter of the obtained lightweight fluidized solidified soil is greater than 16 cm, and the density is less than 1.35 g / cm 3 , and the lightweight fluidized solidified soil is subjected to on-site pouring construction, which can be used as solidified soil to backfill engineering trenches or as building materials. The present invention mainly injects carbon dioxide into the shield slurry and industrial solid waste, and at the same time combines the surfactant or air-entraining agent, foam stabilizer and defoaming agent in the shield slurry itself to adjust the size of the bubble diameter during the reaction process, so as to prepare lightweight fluidized solidified soil with excellent performance, and efficiently utilize the difficult-to-treat surfactant in the shield slurry, reduce the treatment process of the shield slurry, and improve the utilization efficiency of the shield slurry.

[0018] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically gives the specific embodiments of the present invention. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0020] Figure 1 This is a flowchart of a preparation method for a carbonizable shield soil-based lightweight fluidized solidified soil in the present invention. Detailed implementation manners

[0021] The following will specifically elaborate on the present invention in combination with the detailed implementation manners and embodiments, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these detailed implementation manners and embodiments are used to illustrate the present invention rather than limit the present invention.

[0022] Throughout the specification, unless otherwise specifically stated, the terms used herein should 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 meanings as those generally understood by those skilled in the art to which the present invention pertains. In case of any contradiction, this specification shall prevail.

[0023] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or by existing methods.

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

[0025] The shield soil not only contains surfactants but also contains foaming agents. When preparing lightweight fluidized solidified soil using shield soil as a raw material, not only can the addition amounts of air-entraining agents, foam stabilizers, and defoaming agents be reduced, but also the shield soil can be "turned waste into treasure" to achieve the resource utilization of the shield soil. Among them, the main components of the foaming agent include foaming components, foam stabilizing components, and functional components; the foaming components are the main components of the foaming agent, responsible for generating foam, and their quality and ratio directly affect the foam generation amount and stability of the foaming agent; the foam stabilizing components are responsible for increasing the stability and durability of the foam and preventing premature decomposition or failure during use; the functional components are added according to specific requirements, such as preservatives, antifreeze agents, etc., to improve the overall performance of the foaming agent.

[0026] In addition, by incorporating carbon dioxide bubbles on the basis of the fluidized solidified soil, not only can lightweight fluidized solidified soil be formed, which has a lighter density and better fluidity, reduces the load on the lower foundation structure, and improves the sealing effect, but also the gelling effect can be strengthened to achieve carbon utilization and carbon sequestration.

[0027] Based on this, the present invention proposes a method for preparing lightweight fluidized solidified soil by using shield soil and industrial solid waste as the main components and injecting carbon dioxide, so as to meet the requirements of engineering trench backfilling construction.

[0028] Please refer to Figure 1, the present invention provides a preparation method of carbonizable shield soil-based lightweight fluidized solidified soil, and the preparation method includes the following steps: adjusting the water content of the shield soil to 1.9-2.2 times the liquid limit of the shield soil to obtain shield slurry; adding industrial solid waste to the shield slurry and stirring evenly to obtain an initial mixture, and the addition amount of the industrial solid waste is 20-30% of the dry weight of the shield slurry; judging whether an air-entraining agent needs to be added to the initial mixture according to the concentration of the surfactant in the shield soil; when the leaching concentration ≤ 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 evenly to obtain lightweight fluidized solidified soil; when the leaching concentration > 20 mg / L, adding a foam stabilizer to the initial mixture, stirring evenly to obtain a first mixture, and uniformly injecting carbon dioxide gas into the first mixture to obtain lightweight fluidized solidified soil; performing on-site pouring construction on the lightweight fluidized solidified soil; wherein, the flow diameter of the lightweight fluidized solidified soil is greater than 16 cm, and the density of the lightweight fluidized solidified soil is less than 1.35 g / cm 3 .

[0029] Specifically, for the preparation method of carbonizable shield soil-based lightweight fluidized solidified soil provided by the present invention, first, adjust the water content of the shield soil to 1.9-2.2 times the liquid limit of the shield soil to obtain shield slurry; secondly, add industrial solid waste to the shield slurry and adjust the addition amount of the industrial solid waste to 20-30% of the dry weight of the shield slurry, so that the industrial solid waste can be used as a curing agent to modify the shield slurry and improve the comprehensive performance of the shield slurry, thereby obtaining an initial mixture; then, judge whether an air-entraining agent needs to be added to the initial mixture according to the concentration of the surfactant in the shield soil. The air-entraining agent can improve the fluidity of the initial mixture and make it easy to stir and mix evenly. When an air-entraining agent needs to be added, dissolve the air-entraining agent, stabilizer and defoaming agent in water to prepare carbon dioxide foam, and add the carbon dioxide foam to the initial mixture and stir evenly to obtain lightweight fluidized solidified soil. The carbon dioxide foam can not only solidify the harmful substances in the shield slurry and industrial waste, but also control the size of the bubble diameter in the reaction process; when an air-entraining agent does not need to be added, add a foam stabilizer to the initial mixture, stir evenly to obtain a first mixture, and uniformly inject carbon dioxide gas into the first mixture to obtain lightweight fluidized solidified soil. The pre-added foam stabilizer can control the diameter of the bubbles generated by the carbon dioxide gas in the mixture, and at the same time, the generated carbonate can solidify the harmful substances in the shield slurry and industrial waste; finally, the obtained lightweight fluidized solidified soil has a flow diameter greater than 16 cm and a density less than 1.35 g / cm 3, and the lightweight fluidized solidified soil is poured on-site for construction. It can be used as solidified soil for backfilling engineering trenches or as building materials. The present invention mainly prepares excellent-performance lightweight fluidized solidified soil by injecting carbon dioxide into shield mud and industrial solid waste, and at the same time adjusting the bubble diameter size during the reaction by combining the surfactant or air-entraining agent, foam stabilizer and defoaming agent in the shield mud itself, and efficiently utilizes the difficult-to-treat surfactant in the shield mud, reduces the treatment process of the shield mud, and improves the utilization efficiency of the shield mud.

[0030] It should be added that in the present invention, shield soil includes shield mud, shield dried soil and shield muck. The shield mud is at the bottom of the sedimentation tank at the shield construction site or the muck treatment plant. The shield dried soil is the dried soil after screening and dehydration treatment at the shield construction site or the muck treatment plant. The shield muck is the shield muck with a sand content of less than 50% produced during earth pressure balance construction and does not require screening treatment.

[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] Those skilled in the art can understand that using steel slag, carbide slag, blast furnace slag and cement as the solidifying agent in this embodiment can improve the performance of shield mud, and at the same time consume industrial solid waste to achieve the recycling of waste resources. Among them, the content of metal oxides such as calcium and magnesium in steel slag and carbide slag is relatively high, which can form stable carbonates with carbon dioxide, thereby solidifying harmful substances in shield mud; the pozzolanic activity of blast furnace slag and cement is relatively high, which can react with calcium oxide to generate hydrates with hydraulic cementing ability, thereby improving the strength of the solidified soil. In a specific embodiment, cement may not be used, reducing carbon emissions during the production process.

[0033] In some possible embodiments, the preparation of carbon dioxide foam by dissolving the air-entraining agent, foam stabilizer and defoaming agent in water includes: respectively weighing the air-entraining agent, foam stabilizer and defoaming agent, and dissolving them in water to obtain a mixed solution; injecting carbon dioxide gas into the mixed solution through a bubble generator, and the aeration pressure is 0.3 - 0.5 MPa to obtain carbon dioxide foam; 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 mud; the diameter of the carbon dioxide foam is 100-200 μm.

[0035] This is because the air-entraining agent can improve the workability, water retention and cohesion of the mud mixture by introducing a large number of tiny air bubbles, and enhance the fluidity, frost resistance and durability of the mud mixture; the foam stabilizer can prevent the air bubbles formed by the air-entraining agent and carbon dioxide from breaking; the defoaming agent can convert large air bubbles into small air bubbles, making the bubble sizes uniform and facilitating the reaction process.

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

[0037] Those skilled in the art can understand that when the shield mud contains a surfactant, the surfactant can be used as an air-entraining agent, and a foam stabilizer is added at the same time, so that the air bubbles generated by the injected carbon dioxide are in the range of 100-200 μm, efficiently utilizing the surfactant in the shield mud that is difficult to treat and realizing the recycling of resources.

[0038] In some possible embodiments, after the lightweight flowable solidified soil is cast on site, it further includes: after the lightweight flowable solidified soil is cast, covering it with a plastic film or non-woven geotextile and sprinkling water for moisture conservation for 7 days.

[0039] Since the lightweight flowable solidified soil is a new type of engineering material with certain strength, water stability, low permeability and durability, when it is used as a soil material for backfilling trenches, the construction method is simple and easy to operate.

[0040] Based on a general inventive concept, the second aspect of the present invention provides a carbonizable shield soil-based lightweight fluidized solidified soil, and the lightweight fluidized solidified soil comprises the following components: shield mud, 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 mud, 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; wherein, the flow diameter of the lightweight fluidized solidified soil is greater than 16 cm, and the density of the lightweight fluidized solidified soil is less than 1.35 g / cm 3 .

[0041] Specifically, a carbonizable shield soil-based lightweight fluidized solidified soil provided by the present invention comprises the following components: shield mud, industrial solid waste, air-entraining agent, foam stabilizer, defoaming agent and carbon dioxide. Taking the shield mud as the main component of the lightweight fluidized solidified soil and the industrial solid waste as the solidifying agent, the strength of the shield mud is improved by the industrial solid waste. At the same time, the diameter of the bubbles generated by the carbon dioxide is controlled by the air-entraining agent, the foam stabilizer and the defoaming agent, so as to provide a reaction site for the formation of carbonates by the carbon dioxide with calcium and magnesium in the shield mud and the industrial solid waste, so as to solidify its harmful substances; further, the surfactant in the shield mud can be fully utilized as the air-entraining agent, reducing the addition of raw materials and the treatment process of the shield mud. The present invention uses carbon dioxide as the bubble generating component, which can effectively solidify the harmful substances in the shield mud. Using the industrial solid waste as the solidifying agent can improve the strength of the solidified soil, realize the recycling of waste resources, and effectively reduce carbon emissions.

[0042] Combined with the second aspect of the present application, the shield mud is made by adjusting the moisture content of the shield soil, and the moisture content of the shield mud 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 moisture content of the shield mud to be 1.9-2.2 times the liquid limit of the shield soil, the reaction process can be adjusted, so as to adjust the flow diameter and density of the lightweight fluidized solidified soil.

[0044] Combined with the second aspect of the present application, 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).

[0045] Combined with the second aspect of the present application, the air-entraining agent includes at least one of sodium lauryl ether sulfate and sodium dodecylbenzenesulfonate; the foam stabilizer includes at least one of silicone resin polyether emulsion, alkyl dimethylamine oxide, alkyl alkanolamide, lauryl alcohol, and lauroyl diethanolamine; the defoaming agent includes one of polyvinyl alcohol and polyether alcohol.

[0046] In a specific embodiment, sodium lauryl ether sulfate is selected as the air-entraining agent. Sodium lauryl ether sulfate has strong wetting and dispersibility, and rich foaming power. It is suitable for scenarios that require a large amount of foam. When used as an air-entraining agent in solidified soil, it can improve the water retention and cohesion during the raw material mixing process, and improve the durability and frost resistance of the solidified soil; the foam stabilizer can increase the viscosity of foaming, reduce the force under external force, so that the foam is finer and more uniform; the defoaming agent has excellent defoaming ability, stable chemical properties, and high safety. In addition, since shield mud is generated by a shield machine during the excavation of underground space, surfactants may be added during the excavation process to improve the excavation efficiency. Therefore, the shield mud may contain untreated surfactants. In a specific embodiment, the operator can add corresponding air-entraining agents, foam stabilizers, and defoaming agents according to the types of surfactants in the shield mud.

[0047] The following further elaborates the present application in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions noted in the following embodiments are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0048] Example 1

[0049] The shield soil selected in this embodiment is the dried mud cake after dehydration treatment at the shield construction site, and the leaching concentration of the surfactant is 362 mg / L. The detection method of the surfactant leaching concentration: after leaching the dried mud cake and water at a solid-liquid ratio of 1:10, the concentration of the surfactant in the leachate is detected; the preparation method of the carbonizable shield soil-based lightweight fluid solidified soil thus prepared specifically includes the following steps:

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

[0051] (2) Select steel slag, carbide slag, and blast furnace slag with a mass ratio of 4:3:3 as industrial solid wastes, add the industrial solid wastes to the shield mud, and the addition amount of the industrial solid wastes is 30% of the dry weight of the shield mud, and stir evenly to obtain an initial mixture;

[0052] (3) Add a foam stabilizer to the initial mixture. The mass of the foam stabilizer is 0.03% of the dry weight of the shield mud. Stir evenly to obtain the first mixture.

[0053] (4) Uniformly blast carbon dioxide gas into the first mixture through a bubble generator. The blasting pressure is 0.7 MPa, and the blasting volume is 3% of the volume of the shield mud. The diameter of the bubbles generated by the carbon dioxide gas is 100 - 200 μm, obtaining a lightweight fluidized solidified soil with a density of 1.28 g / cm 3 and a flow diameter of 18 cm.

[0054] (5) Inject the lightweight fluidized solidified soil into the trench for on-site pouring. After pouring is completed, immediately cover it with a plastic film or non-woven geotextile and sprinkle water for moisturizing curing for 7 days.

[0055] After detection, 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 the dried mud cake after dehydration treatment at the shield construction site. The leaching concentration of the surfactant is 127 mg / L. The detection method for the leaching concentration of the surfactant: After leaching the dried mud cake and water at a solid-liquid ratio of 1:10, detect the concentration of the surfactant in the leaching solution. The preparation method of the carbonizable shield soil-based lightweight fluidized solidified soil thus prepared specifically includes the following steps:

[0058] (1) Adjust the water content of the shield soil to 2 times its liquid limit to obtain shield mud.

[0059] (2) Select steel slag, carbide slag, blast furnace slag, and cement with a mass ratio of 4:3:3:2 as industrial solid wastes. Add the industrial solid wastes to the shield mud. The addition amount of the industrial solid wastes is 30% of the dry weight of the shield mud. Stir evenly to obtain the initial mixture.

[0060] (3) Add a foam stabilizer to the initial mixture. The mass of the foam stabilizer is 0.05% of the dry weight of the shield mud. Stir evenly to obtain the first mixture.

[0061] (4) Uniformly blast carbon dioxide gas into the first mixture through a bubble generator. The blasting pressure is 0.5 - 0.7 MPa, and the blasting volume is 3% of the volume of the shield mud. The diameter of the bubbles generated by the carbon dioxide gas is 100 - 200 μm, obtaining a second mixture with a flow diameter not less than 16 cm but a density higher than 1.35 g / cm 3 .

[0062] (5) Prepare carbon dioxide foam. Dissolve an air-entraining agent, a foam stabilizer, and an antifoaming 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 antifoaming agent is 0.01% of the dry weight of the shield mud. Introduce carbon dioxide gas into the mixed solution through a bubble generator at a gas-introducing pressure of 0.3 MPa to obtain carbon dioxide foam with a diameter of 100 - 200 μm.

[0063] Add the carbon dioxide foam to the second mixture. The volume of the carbon dioxide foam is 1% of the volume of the shield mud, and stir evenly to obtain lightweight fluidized solidified soil with a density of 1.2 g / cm 3 and a flow diameter of 18.5 cm.

[0064] (6) Inject the lightweight fluidized solidified soil into the trench for on-site pouring. After pouring is completed, immediately cover it with a plastic film or non-woven geotextile and sprinkle water for moisture conservation for 7 days.

[0065] After testing, the carbon dioxide utilization rate is 70%, and the strength of the material soil after 28 days is 0.64 MPa.

[0066] Example 3

[0067] The shield soil selected in this example is the dried mud cake after dehydration treatment at the shield construction site, and the leaching concentration of surface activity is less than 20 mg / L. The preparation method of the carbonizable shield soil-based lightweight fluidized solidified soil specifically includes the following steps:

[0068] (1) Adjust the water content of the shield soil to 2 times its liquid limit to obtain shield mud.

[0069] (2) Select steel slag, carbide slag, blast furnace slag, and cement with a mass ratio of 4:3:3:2 as industrial solid wastes. Add the industrial solid wastes to the shield mud. The addition amount of the industrial solid wastes is 20% of the dry weight of the shield mud, and stir evenly to obtain an initial mixture.

[0070] (3) Prepare carbon dioxide foam. Dissolve an air-entraining agent, a foam stabilizer, and an antifoaming agent 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 antifoaming agent is 0.03% of the dry weight of the shield mud. Introduce carbon dioxide gas into the mixed solution through a bubble generator at a gas-introducing pressure of 0.7 MPa to obtain carbon dioxide foam with a diameter of 100 - 200 μm.

[0071] (4) Add the carbon dioxide foam to the initial mixture. The volume of the carbon dioxide foam is 3% of the volume of the shield mud, and stir evenly to obtain lightweight fluidized solidified soil with a density of 1.26 g / cm 3, lightweight flowable solidified soil with a flow diameter of 19 cm;

[0072] (5) Inject the lightweight flowable solidified soil into the trench for on-site pouring. After pouring is completed, immediately cover it with plastic film or non-woven geotextile and sprinkle water for moisture conservation for 7 days.

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

[0074] Comparative Example 1

[0075] In this comparative example, compared with Example 1, step (3) is omitted, and the other steps remain unchanged. The density of the obtained lightweight flowable solidified soil is 1.46 g / cm 3 . This is because, without the addition of a foam stabilizer, the bubbles in the initial mixture are extremely easy to burst, resulting in the overflow of carbon dioxide gas and an increase in the density of the obtained solidified soil.

[0076] Comparative Example 2

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

[0078] Comparative Example 3

[0079] In this comparative example, compared with Example 1, the addition amount of industrial solid waste is 10% of the dry weight of shield mud, and the other steps remain unchanged. The strength of the soil body of the obtained lightweight flowable solidified soil after 28 days is 0.28 MPa. This is because, with a relatively small addition amount of industrial solid waste, there are fewer hydration products and carbonation products, and the cementing effect is weakened, resulting in a decrease in the strength of the soil body after the solidified soil is poured.

[0080] Comparative Example 4

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

[0082] Comparative Example 5

[0083] In this comparative example, compared with Example 1, carbide slag and blast furnace slag with a mass ratio of 3:3 were selected as industrial solid wastes, and the remaining steps remained unchanged. After testing, the utilization rate of carbon dioxide was 38%. This is because only carbide slag and blast furnace slag were added in this comparative example, and the content of metal oxides such as calcium and magnesium was low, resulting in a low utilization rate of carbon dioxide.

[0084] Comparative Example 6

[0085] In this comparative example, compared with Example 1, the moisture content of the shield soil was adjusted to 1.8 times its liquid limit, and the remaining steps remained unchanged. The flow diameter of the lightweight fluidized solidified soil obtained was 15 cm. This is because the moisture content of the shield mud was low, resulting in a high concentration of industrial solid wastes in the initial mixture. The hydration reaction was intense, and the consistency of the initial mixture became larger, thus reducing the flow diameter of the solidified soil.

[0086] Comparative Example 7

[0087] In this comparative example, compared with Example 1, the moisture content of the shield soil was adjusted to 2.3 times its liquid limit, and the remaining steps remained unchanged. After the lightweight fluidized solidified soil was poured, the soil strength at 28 d was 0.27 MPa. This is because the excessive moisture content of the shield mud led to a low density of the solidified soil, thus 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) By using carbon dioxide gas, the present invention can not only solidify harmful substances in the shield mud, but also reduce carbon emissions during the production process;

[0090] (2) The present invention uses industrial solid wastes such as steel slag, carbide slag, blast furnace slag and cement as curing agents to modify the shield mud, and obtains lightweight fluidized solidified soil with excellent performance, realizing the recycling of waste resources;

[0091] (3) The present invention can make full use of the surfactant in the shield mud that has not been treated, thereby reducing the treatment process of the shield mud and realizing the harmless treatment of the shield mud.

[0092] Finally, it should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0093] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention.

[0094] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing carbonizable shield foundation lightweight fluidized solidified soil, characterized in that: The preparation method comprises the following steps: Adjusting the water content of the shield soil to 1.9-2.2 times the liquid limit of the shield soil to obtain shield slurry; Adding industrial solid waste to the shield mud and stirring evenly to obtain an initial mixture, wherein the amount of the industrial solid waste added is 20-30% of the dry weight of the shield mud; Determining whether it is necessary to add an air entraining agent to the initial mixture according to the leaching concentration of the surfactant in the shield soil; When the leaching concentration is ≤20 mg / 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 light fluidized solidified soil; When the leaching concentration is greater than 20 mg / L, a foam stabilizer is added to the initial mixture, and the mixture is stirred evenly to obtain a first mixture, and carbon dioxide gas is evenly exploded into the first mixture to obtain a light fluidized solidified soil; The lightweight fluidized solidified soil is poured on site; The flow diameter of the light fluidized solidified soil is greater than 16 cm, and the density of the light fluidized solidified soil is less than 1.35 g / cm 3 .

2. The method for preparing carbonizable shield foundation lightweight fluidized solidified soil according to claim 1, characterized in that: 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).

3. The method for preparing carbonizable shield foundation lightweight fluidized solidified soil according to claim 1, characterized in that: The step of dissolving the air entraining agent, the foam stabilizer and the defoamer in water to prepare the carbon dioxide foam comprises: Weigh air entraining agent, foam stabilizer and defoamer respectively, and dissolve them in water to obtain a mixed solution; Exploding carbon dioxide gas into the mixed liquid through a bubble generator at an explosion 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 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 defoamer is 0.01-0.03% of the dry weight of the shield mud.

4. The method for preparing carbonizable shield foundation lightweight fluidized solidified soil according to claim 1 or 3, characterized in that: The volume of the carbon dioxide foam is 0-3% of the volume of the shield mud; the diameter of the carbon dioxide foam is 100-200 μm.

5. The method for preparing carbonizable shield foundation lightweight fluidized solidified soil according to claim 1, characterized in that: The step of adding a foam stabilizer to the initial mixed material, stirring the mixture to obtain a first mixed material, and uniformly exploding carbon dioxide gas into the first mixed material comprises: Weighing a foam stabilizer, the mass of which is 0.03-0.08% of the dry weight of the shield mud; Adding the foam stabilizer to the initial mixed material, stirring evenly, to obtain a first mixed material; Carbon dioxide gas is uniformly exploded into the first mixture through a bubble generator, and the bubble diameter of the carbon dioxide gas is 100-200 μm, the explosion pressure is 0.5-0.7 MPa, and the explosion volume is 3% of the volume of the shield mud.

6. The method for preparing carbonizable shield foundation lightweight fluidized solidified soil according to claim 1, characterized in that: After the lightweight fluidized solidified soil is poured on site, the method further comprises: After the lightweight fluidized solidified soil is poured, it is covered with a plastic film or a non-woven geotextile and watered to maintain moisture for 7 days.

7. A carbonizable shield foundation lightweight fluidized solidified soil, characterized in that: The lightweight fluidized solidified soil comprises the following components: shield mud, 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 shield mud, 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 defoamer is 0.01-0.03% of the dry weight of the shield mud; The flow diameter of the light fluidized solidified soil is greater than 16 cm, and the density of the light fluidized solidified soil is less than 1.35 g / cm 3 .

8. The carbonizable shield foundation lightweight fluidized solidified soil according to claim 7, characterized in that: The shield slurry is produced by adjusting the water content of the shield soil. The water content of the shield slurry is 1.9-2.2 times the liquid limit of the shield soil.

9. The carbonizable shield foundation lightweight fluidized solidified soil according to claim 8, characterized in that: 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).

10. The carbonizable shield foundation lightweight fluidized solidified soil according to claim 7, 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 resin polyether emulsion, alkyl dimethyl amine oxide, alkyl alcohol amide, lauryl alcohol and lauroyl diethanolamine; the defoaming agent includes one of polyvinyl alcohol and polyether alcohol.

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