A gap filling material and method for tunnel segments and full precast track bed structures

Abstract

This invention discloses a filling material and method for the gap between tunnel segments and precast track bed structures, belonging to the field of rail transit technology. It comprises the following components in parts by weight: 15-20 parts of calcined magnesium oxide, 10-20 parts of potassium dihydrogen phosphate, 0-20 parts of fly ash, 20-25 parts of water, 3-5 parts of borax, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 30-40 parts of fine sand. This filling material, under its own weight or pressure, can densely fill the gaps between precast components, forming a high-strength structural filler with good interfacial curing and rigid connection. It can provide an effective protective layer for the connectors between precast components, thus protecting the precast components and their connectors.

Description

Technical Field

[0001] This invention belongs to the field of rail transit technology, specifically relating to a material and method for filling the gap between tunnel segments and fully prefabricated track bed structures. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Prefabricated assembly technology has rapidly developed and been applied in the field of rail transit. It has been used to construct prefabricated subway station structures, prefabricated segment tunnel structures using the shield tunneling method, and prefabricated slab track structures. This technology aligns with the concept of green construction and effectively reduces the impact of rail transit construction on the urban environment and traffic. Prefabricated components can be produced in factories in a standardized and industrialized manner, offering advantages such as high quality control, fewer on-site construction procedures, minimal impact on the construction environment, high degree of mechanization, and low on-site labor requirements. This reduces labor costs and safety risks, improves construction efficiency, shortens the construction period, and significantly enhances the social and economic benefits of engineering projects.

[0004] However, the inventors discovered that urban rail transit projects using prefabricated assembly construction, in addition to the connectors between components, also have structural gaps between prefabricated components due to factors such as production errors of the components themselves, assembly errors caused by the construction process, and deformation errors caused by uneven external forces. Under normal construction conditions, the gap range is about 0-10mm, or even larger, exceeding the range of errors caused by normal construction. Especially in the gap between shield tunnels and fully prefabricated track bed structures, when water enters the gap, it is easy to cause corrosion of the connectors. At the same time, during operation, the long-term reciprocating load of trains causes repeated contact between the concrete surfaces of the prefabricated components, which can lead to damage to the concrete surfaces of the contacting prefabricated components. In severe cases, it can affect the durability of the prefabricated component structure and the safety of line operation during long-term service. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a filling material and method for gaps between tunnel segments and prefabricated track bed structures. This involves preparing a high-strength filling material suitable for the rigid connection and curing of gaps between prefabricated components. Under its own weight or pressure, the filling material can densely fill the gaps between prefabricated components (the gap range is approximately 0-10mm under normal construction conditions), forming a high-strength structural filler with good interface curing and rigid connection. This addresses the structural integrity issues arising from gap filling in prefabricated assembled components and provides an effective protective layer for the connectors between prefabricated components, thus protecting the prefabricated components and their connectors. This provides a crucial interface curing and rigid connection high-strength structural filler for shield tunnel segments and prefabricated track bed structures, enabling rapid integrated construction of shield tunnels and prefabricated track bed components. Ultimately, this achieves the goal of a tunnel integrated prefabricated assembly system with excellent structural integrity and durability.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a filling material for the gap between tunnel segments and a fully prefabricated track bed structure, comprising the following components in parts by weight:

[0008] 15-20 parts of recalcined magnesium oxide, 10-20 parts of potassium dihydrogen phosphate, 0-20 parts of fly ash, 20-25 parts of water, 3-5 parts of borax, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 30-40 parts of fine sand.

[0009] As a further technical solution, the recalcined magnesia contains more than 80% magnesia, has a calcination temperature of 1600–1700℃, and a specific surface area of ​​235–255 m². 2 / kg.

[0010] As a further technical solution, the potassium dihydrogen phosphate is of analytical grade and has a particle size of less than 100 mesh.

[0011] As a further technical solution, the fly ash is grade F fly ash, with more than 70% of the fly ash having a particle size of less than 45 μm and a calcareous content of less than 7%.

[0012] As a further technical solution, the polyvinyl alcohol has a medium degree of polymerization and a molecular weight of 120,000 to 150,000.

[0013] As a further technical solution, the polypropylene fiber has a coarseness of 5-10 dtex and a fiber length of 2-5 cm; the fine sand has a diameter of 0.1-0.25 mm and a moisture content of no more than 6%.

[0014] Secondly, the present invention also provides a method for preparing the gap filling material between tunnel segments and fully prefabricated track bed structure as described above, comprising the following steps:

[0015] Remove debris from the gaps between the shield tunnel segments and the fully prefabricated track bed structure;

[0016] Mix 15-20 parts of reburned magnesium oxide, 3-5 parts of borax, 30-40 parts of fine sand, 0-20 parts of fly ash, and 15-20 parts of water to form slurry A;

[0017] Mix 10-20 parts of potassium dihydrogen phosphate, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 5-8 parts of water to form slurry B.

[0018] Mix slurry A and slurry B thoroughly to form a filling material;

[0019] The mixture of slurry A and slurry B is poured into the gap between the shield tunnel segments and the prefabricated structural components, and the gap is filled by gravity flow or pressure-assisted grouting.

[0020] As a further technical solution, during the preparation of slurry A, heating and stirring are carried out at a temperature of 95-105℃.

[0021] As a further technical solution, during the preparation of slurry B, the mixture is stirred at a speed of 100-120 r / min for 2-5 min to form slurry B.

[0022] Thirdly, the present invention also provides the application of the material described above for filling the gap between tunnel segments and fully prefabricated track bed structures in civil engineering.

[0023] The beneficial effects of the present invention are as follows:

[0024] The gap-filling material of the present invention for the space between shield tunnel segments and fully prefabricated track bed structure, through the combined action of the above material components, can form a filling material with good injectability, crack resistance, and permeability coefficient. It can solve the structural integrity problem after gap filling of fully prefabricated assembled components. At the same time, it can provide an effective protective layer for the connectors between prefabricated components, which is beneficial to protecting the prefabricated components and their connectors. It provides an important interface-curing rigid connection structure for shield tunnel segments and fully prefabricated track bed structure, which is an important link in realizing the integrated full assembly and rapid construction of shield tunnel and fully prefabricated track bed and other assembled components, and achieves the goal of excellent integrity of the fully prefabricated combined structure.

[0025] Currently, the traditional cast-in-place track foundation construction suffers from slow concrete mixing, transportation, and on-site pouring speeds. This invention addresses the problem of filling the gaps between shield tunnel segments and the fully prefabricated track structure using a filling material. This allows for factory production of the fully prefabricated track structure components, ensuring high quality and precision. Mechanized transportation and hoisting operations significantly reduce labor intensity. Modular on-site assembly greatly reduces construction steps, resulting in fast construction speed, high precision, and excellent performance. It significantly shortens the time required for traditional on-site concrete mixing, transportation, pouring, and curing, and can be combined with mechanized shield tunneling machine assembly equipment to achieve immediate assembly after segment completion. Mechanized assembly construction of track bed foundations can effectively overcome the disadvantages of existing cast-in-place track bed foundation construction, such as multiple construction steps, high labor intensity of manual main operations, difficulty in controlling construction accuracy, and slow construction speed. It realizes the rapid construction of all prefabricated assembly of track bed structure components, maximizes the speed, efficiency and high quality of track bed structure construction, establishes a rapid construction system for the full prefabrication and assembly of the main components of shield tunnels, and conforms to the green development concept of prefabrication industrialization, assembly, energy conservation and emission reduction in the construction industry. It promotes the high-quality and sustainable development of prefabricated structures in the field of urban rail transit from the source. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0027] Figure 1 This is a schematic diagram illustrating the cooperation between the shield tunnel segments and the fully prefabricated track bed structure of the present invention;

[0028] In the diagram: the spacing or dimensions between parts have been exaggerated to show their positions; the diagram is for illustrative purposes only.

[0029] Among them, 1-shield tunnel segment; 2-fully prefabricated track bed structure unit; 3-connector between prefabricated structures; 4-interface gap filling material. Detailed Implementation

[0030] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] As described in the background section, there are certain structural gaps between precast components. Existing filling materials usually have the disadvantages of poor interfacial bonding and long time interval between initial and final setting. They cannot meet the requirements of high-strength rigid connection between precast reinforced concrete components under long-term cyclic loads to form a structure with excellent integrity. In order to address the above problems, this application proposes a filling material for the gap between shield tunnel segments and fully precast track structure.

[0032] In a typical embodiment of the present invention, a filling material for the gap between tunnel segments and fully prefabricated track bed structure is proposed, the material components of which include calcined magnesium oxide, potassium dihydrogen phosphate, fly ash, water, borax, polyvinyl alcohol, alkyl sulfonate, polypropylene fiber and fine sand.

[0033] Specifically, the filling material is composed of the following components and mass ratios in parts by weight: 15-20 parts of calcined magnesium oxide, 10-20 parts of potassium dihydrogen phosphate, 0-20 parts of fly ash, 20-25 parts of water, 3-5 parts of borax, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 30-40 parts of fine sand. This formulation forms a filling material for the gap between shield tunnel segments and the fully prefabricated track bed structure. This material features rapid setting, good interfacial adhesion, high early strength, good durability, and strong impact resistance, significantly improving the stability of train tracks.

[0034] In the preferred embodiment, the recalcined magnesium oxide is a yellow powder with a magnesium oxide content greater than 80%, a calcination temperature of 1600–1700℃, and a specific surface area of ​​235–255 m². 2 / kg, with a more preferred specific surface area of ​​245m². 2 / kg.

[0035] In the preferred embodiment, the potassium dihydrogen phosphate is of analytical grade, in powder form, and has a particle size of less than 100 mesh.

[0036] In the preferred embodiment, the fly ash is grade F fly ash, with more than 70% of the fly ash having a particle size less than 45 μm and a calcareous content of less than 7%.

[0037] In the preferred embodiment, the water is tap water.

[0038] In the preferred embodiment, the borax is in powder form with a particle size of 100 mesh.

[0039] In the preferred embodiment, polyvinyl alcohol can be of medium degree of polymerization, with a molecular weight of 120,000 to 150,000.

[0040] In the preferred embodiment, alkyl sulfonate is used as a plasticizer, which can significantly reduce the fluidity of the filling material and ensure the compactness of the slurry.

[0041] In the preferred embodiment, the polypropylene fibers have a thickness of 5-10 dtex and a fiber length of 2-5 cm.

[0042] In the preferred embodiment, the fine sand has a diameter between 0.1 and 0.25 mm and a moisture content not exceeding 6%.

[0043] Because existing filling materials usually have the disadvantages of poor overall performance of interfacial bonding and long time interval between initial and final setting, they are generally used for interfacial bonding between reinforced concrete structural members, but are not suitable for forming a prefabricated composite structural system with excellent integrity and durability through high-strength rigid connection between fully prefabricated reinforced concrete members under long-term cyclic load.

[0044] The inventors discovered in their experimental research that by adding F-grade fly ash in a reasonable proportion, the acid-base neutralization reaction characteristics of phosphate cement can be fully utilized to activate the fly ash with alkali, which is beneficial to improving the overall strength of the filling material, improving the workability of the fresh mixture, reducing the heat of hydration, and thus reducing material costs.

[0045] The inventors also discovered that adding polyvinyl alcohol in a reasonable proportion can significantly improve the impermeability of the filling material. Polyvinyl alcohol can prolong the setting time of the grout to a certain extent, improve the workability of the grout, and form a film structure between each set layer, significantly reducing the porosity of the filling material, thereby improving the impermeability of the grout.

[0046] The inventors also discovered that polypropylene fibers can effectively enhance the crack resistance of the stone body, thereby improving its impact resistance during train operation and significantly reducing the durability and impermeability of the stone body.

[0047] The inventors also discovered that alkyl sulfonates can effectively improve the fluidity of slurry and increase the density of slurry injection.

[0048] This filling material, through the combined action of the above components, can form a filling material with good injectability, good crack resistance, and excellent permeability; none of these components can be omitted.

[0049] This filling material can be used to fill the pre-existing pores in precast reinforced concrete structures and the gaps between precast structural components.

[0050] In another typical embodiment of the present invention, a method for preparing the filling material as described above is proposed, comprising the following steps:

[0051] Step 1: Use high-pressure cleaning equipment to remove dust, water and other debris from the gap between the shield tunnel segments and the fully prefabricated track bed structure;

[0052] Step 2: Mix 15-20 parts of reburned magnesium oxide, 3-5 parts of borax, 30-40 parts of fine sand, 0-20 parts of fly ash, and 15-20 parts of water to form slurry A;

[0053] Step 3: Mix 10-20 parts of potassium dihydrogen phosphate, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 5-8 parts of water to form slurry B;

[0054] Step 4: Mix slurry A and slurry B thoroughly to form the filling material;

[0055] Step 5: Pour the mixture of slurry A and slurry B into the gap between the shield tunnel segment and the prefabricated structural component. Fill the gap between the shield tunnel segment and the prefabricated structural component by gravity flow or pressure-assisted grouting. After 24 hours, it reaches 80% of the strength value, and after 3 days, it reaches 100% of the strength value.

[0056] Furthermore, during the preparation of slurry A, heating and stirring are carried out at a temperature of 95-105℃, preferably 100℃.

[0057] Furthermore, during the preparation of slurry B, the mixture is stirred at a speed of 100-120 r / min for 2-5 min to form slurry B, preferably at a speed of 100 r / min for 5 min.

[0058] In another typical embodiment of the present invention, the application of the filling material as described above in civil engineering is also provided.

[0059] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments and comparative examples.

[0060] Example 1:

[0061] A filling material for the gap between shield tunnel segments and precast track bed structure, by weight, is: calcined magnesium oxide: potassium dihydrogen phosphate: fly ash: water: borax: polyvinyl alcohol: alkyl sulfonate: polypropylene fiber: fine sand = 1:0.75:0.75:1:0.15:0.01:0.01:0.01:1.5.

[0062] Its preparation method includes the following steps:

[0063] 1) Weigh out the corresponding amounts of calcined magnesium oxide, potassium dihydrogen phosphate, fly ash, water, borax, polyvinyl alcohol, alkyl sulfonate, polypropylene fiber, and fine sand according to the proportions and set aside.

[0064] 2) Mix calcined magnesium oxide, borax, fine sand, fly ash and water to form slurry A. Heat and stir in a reactor at 100°C until the slurry is uniform to form slurry A.

[0065] 3) Mix potassium dihydrogen phosphate, polyvinyl alcohol, alkyl sulfonate, polypropylene fiber and water to form slurry B. Stir the mixture in a mixer at 100 r / min for 5 min to form slurry B.

[0066] 4) After thoroughly mixing grout A and grout B, a filling material is formed for the gap between the tunnel segments and the fully precast track bed structure. The formed grouting material is then poured into 20-30m... 3 Pour the material into the mold at a pouring speed of / h. After the outer surface of the material has initially set, apply a finishing coat. Let it stand in a dry and ventilated place indoors for 1-2 hours before demolding. After demolding, place it in a standard curing room with a temperature of (23±3)℃ and a relative humidity of over 95% for 3 days and 28 days.

[0067] Example 2:

[0068] A filling material for the gap between shield tunnel segments and prefabricated track bed structure, by weight, is composed of: calcined magnesium oxide: potassium dihydrogen phosphate: fly ash: water: borax: polyvinyl alcohol: alkyl sulfonate: polypropylene fiber: fine sand = 1:0.75:0.5:1:0.15:0.01:0.01:0.01:1.

[0069] Its preparation method includes the following steps:

[0070] 1) Weigh out the corresponding amounts of calcined magnesium oxide, potassium dihydrogen phosphate, fly ash, water, borax, polyvinyl alcohol, alkyl sulfonate, polypropylene fiber, and fine sand according to the proportions and set aside.

[0071] 2) Mix calcined magnesium oxide, borax, fine sand, fly ash and water to form slurry A. Heat and stir in a reactor at 100°C until the slurry is uniform to form slurry A.

[0072] 3) Mix potassium dihydrogen phosphate, polyvinyl alcohol, alkyl sulfonate, polypropylene fiber and water to form slurry B. Stir the mixture in a mixer at 100 r / min for 5 min to form slurry B.

[0073] 4) After thoroughly mixing grout A and grout B, a filling material is formed for the gap between the tunnel segments and the fully precast track bed structure. The formed grouting material is then poured into 20-30m... 3 Pour the material into the mold at a set pouring speed of / h. After the outer surface of the material has initially set, apply a finishing coat. Let it stand in a dry and ventilated place indoors for 1-2 hours before demolding. After demolding, place it in a standard curing room with a temperature of (23±3)℃ and a relative humidity of over 95% for 3 days and test its tensile and compressive strength.

[0074] Comparative Example 1:

[0075] The preparation method is the same as in Example 1, except that the polyvinyl alcohol content is 0.

[0076] Comparative Example 2:

[0077] The preparation method is the same as in Example 2, the only difference being that the polypropylene fiber content is 0.

[0078] Comparative Example 3:

[0079] The preparation method is the same as in Example 2, except that the alkyl sulfonate content is 0.

[0080] The performance of the filling materials prepared in Examples 1-2 and Comparative Examples 1-3 was tested, and the test results are shown in the table below:

[0081]

[0082] As can be seen from the parameters in the table, adding water glass and fly ash shortens the setting time and increases the interfacial adhesion of the prepared material; adding polyvinyl alcohol can significantly improve the freeze-thaw cycle resistance of the material; adding polypropylene fiber can significantly increase the tensile strength and thaw resistance of the filling structure; and adding alkyl sulfonate can effectively increase the rheological properties of the slurry, thereby improving the workability of the slurry.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A filling material for the gap between tunnel segments and a fully prefabricated track bed structure, characterized in that, It consists of the following components in parts by weight: 15-20 parts of recalcined magnesium oxide, 10-20 parts of potassium dihydrogen phosphate, 0-20 parts of fly ash, 20-25 parts of water, 3-5 parts of borax, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 30-40 parts of fine sand; The fly ash is Grade F fly ash, with more than 70% of the fly ash having a particle size smaller than 45 μm and a calcareous content of less than 7%. The polyvinyl alcohol used has a medium degree of polymerization and a molecular weight of 120,000 to 150,000. The fine sand has a diameter between 0.1 and 0.25 mm and a moisture content of no more than 6%.

2. The material for filling the gap between tunnel segments and the fully prefabricated track bed structure as described in claim 1, characterized in that, The recalcined magnesia contains more than 80% magnesia, is calcined at 1600-1700℃, and has a specific surface area of ​​235-255 m². 2 / kg.

3. The material for filling the gap between tunnel segments and the fully prefabricated track bed structure as described in claim 1, characterized in that, The potassium dihydrogen phosphate is of analytical grade and has a particle size of less than 100 mesh.

4. The material for filling the gap between tunnel segments and the fully prefabricated track bed structure as described in claim 1, characterized in that, The polypropylene fibers have a thickness of 5-10 dtex and a length of 2-5 cm.

5. The method for preparing the gap filling material between tunnel segments and fully prefabricated track bed structure as described in any one of claims 1-4, characterized in that, Includes the following steps: Remove debris from the gaps between the shield tunnel segments and the fully prefabricated track bed structure; Mix 15-20 parts of reburned magnesium oxide, 3-5 parts of borax, 30-40 parts of fine sand, 0-20 parts of fly ash, and 15-20 parts of water to form slurry A; Mix 10-20 parts of potassium dihydrogen phosphate, 0.1-0.3 parts of polyvinyl alcohol, 0.1-0.5 parts of alkyl sulfonate, 0.1-0.15 parts of polypropylene fiber, and 5-8 parts of water to form slurry B. Mix slurry A and slurry B thoroughly to form a filling material; The mixture of slurry A and slurry B is poured into the gap between the shield tunnel segments and the prefabricated structural components, and the gap is filled by gravity flow or pressure-assisted grouting.

6. The preparation method according to claim 5, characterized in that, During the preparation of slurry A, heating and stirring are carried out at a temperature of 95-105℃.

7. The preparation method according to claim 5, characterized in that, During the preparation of slurry B, stir at a speed of 100-120 r / min for 2-5 min to form slurry B.

8. The application of a material for filling the gap between tunnel segments and fully prefabricated track bed structures as described in any one of claims 1-4 in civil engineering.

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