Method for preparing lightweight fillers, railway substructure and method for laying thereof

Abstract

The application discloses a preparation method of light filler, a railway roadbed structure and a laying method of the railway roadbed structure. The preparation method comprises the following steps: raw materials and proportioning: a liquid foaming agent which is composed of silicate cement, fly ash, hollow glass microbeads, polycarboxylic acid water reducing agent, alkyl sulfonic acid alkali metal salt and hydrolyzed protein in a mass ratio; a preparation process of the light filler, comprising the following steps: dilution and foaming of the foaming agent; mixing and stirring; forming and curing; light filler bulk density design: accurate calculation of the total volume of mixed dry materials, the total volume of required water and the quality of light filler foam, and determination of the design density of the light filler. The application can realize rapid repair and emergency response, adapt to extreme environment, improve structural stability, enhance durability, improve heat and sound insulation performance, balance light weight and high strength, and is environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-speed railway subgrade engineering, in particular to a preparation method of light filler, a railway subgrade structure and a laying method thereof. BACKGROUND

[0002] Faster running speed puts higher requirements on the smoothness and stability of the line. The structural vibration caused by high-speed railway vehicles is transmitted outward through the subgrade to the surrounding ground, which not only endangers the safety performance of the wheel-rail system itself, but also has an adverse effect on the durability of the high-speed railway subgrade structure. There are various types of vibration reduction measures for high-speed railway subgrades, but the effects are uneven, and generally there is the shortcoming of high cost but not obvious effect.

[0003] A large number of studies on subgrade fillers show that the deformation of the bed surface layer and the bed bottom layer can account for more than 50% of the total deformation of the entire subgrade. With the rapid development of high-speed railways, the study of the strength and deformation characteristics of high-speed railway subgrade fillers has become a hot issue. The use of shock absorption and isolation materials can effectively reduce the deformation behavior of high-speed railway subgrades under dynamic load. If a new type of shock absorption and isolation filler can be developed and widely applied to the subgrade materials of high-speed railways, achieving industrialization and popularization, this problem will be solved to a great extent. At present, the assembly structure and construction technology have become one of the important trends in the development of railway engineering construction. The existing light high-strength concrete and other materials can play a role in strengthening the performance of the subgrade through mechanical foaming effect in the construction of high-speed railway subgrades. Good integrity and low permeability coefficient can reduce subgrade diseases. However, as an assembly mechanism filler, how to uniformly improve its basic mechanical properties, vibration reduction performance, corrosion resistance, durability and other properties still needs further research and demonstration.

[0004] Prior art scheme:

[0005] (1) A construction method for municipal road and abutment backfill based on light filler (CN110219216B)

[0006] China Railway No. 16 Bureau Group Co., Ltd. discloses a construction method for municipal road and abutment backfill based on light filler, which comprises the following steps: mixing and stirring cement, light aggregate and water to obtain cement slurry; using a foaming machine to fully foam a foaming agent to obtain foam; mixing the obtained foam and the cement slurry to obtain light filler; directly pumping the obtained light filler and pouring in a segmented manner; within 3-12 hours after pouring the light filler, maintaining the light filler by covering with grass pulp, reed mat, burlap, sawdust, wet soil or wet sandy soil and watering, and the maintenance time of the light filler is not less than 7 days. The construction method applies light filler to municipal road and abutment backfill, which improves the problem of uneven settlement of the subgrade and the bridge; and the installation of a single-layer steel wire mesh in the light filler improves the integrity of the light filler.

[0007] (2) A lightweight filler for bridge arch filling (CN107265953B)

[0008] A lightweight filler for bridge arch filling invented by Southeast University is composed of the following mass parts: 500-600 parts of PⅡ52.5 or 42.5 cement, 60-240 parts of lithium slag, 2-3 parts of foaming agent, 3-4 parts of water reducing agent, 10-30 parts of alkali-resistant glass fiber, 2-5 parts of emulsion waterproof agent, 12-100 parts of styrene-acrylic emulsion powder, 1-3 parts of thickening agent, and 250-300 parts of water. After the lightweight filler is poured for 28 days, a silane hybrid silicone waterproof coating is impregnated on the surface of the lightweight filler concrete. This method uses cement, lithium slag, water, water reducing agent, styrene-acrylic emulsion powder, alkali-resistant glass fiber, fluorosilicone acrylate emulsion waterproof agent, etc. to prepare the lightweight filler, and impregnates a silane hybrid silicone waterproof coating on the surface of the lightweight filler. Compared with ordinary lightweight fillers, the strength is higher, the water absorption and settlement rate are greatly reduced, and the durability is significantly enhanced. It can be used as a bridge arch filler to solve the problems of high water absorption, serious settlement, and poor durability of ordinary lightweight fillers.

[0009] These two lightweight filler subgrade structures still have some defects and challenges in actual application. The following is the main defect analysis of the lightweight filler full bed subgrade and the lightweight filler bed subgrade:

[0010] Cracking problem caused by structural stiffness difference:

[0011] In the application of lightweight filler materials in highway bridge transition sections, when the lower structure has stiffness difference or uneven deformation, especially on the foundation with weak bearing capacity, it is easy to cause instability of the overall structure. This instability first forms cracks in the lower structure, then the cracks extend to the top, and then may cause damage to the overall structure. Due to the lower elastic modulus of lightweight filler compared with traditional concrete, this difference exacerbates the risk of uneven settlement.

[0012] Quality and paving requirements of graded crushed stone:

[0013] When the lightweight filler bed subgrade uses graded crushed stone as the surface layer, it puts forward higher requirements for the quality and paving technology of the crushed stone. The uniformity and thickness control of the crushed stone layer are crucial to the stability and drainage performance of the overall subgrade. If the crushed stone layer is not evenly paved or the drainage design is improper, it may cause water accumulation, thereby affecting the stability and durability of the subgrade.

[0014] High cost problem:

[0015] The production and transportation costs of lightweight fillers are generally higher than traditional concrete materials. In addition, the construction techniques of these subgrade structures require higher technical requirements, professional equipment and technical personnel. These factors together can significantly increase the cost of the entire road project, especially in large-scale infrastructure construction.

[0016] Vulnerability in harsh weather conditions:

[0017] Lightweight filler subgrade in harsh weather conditions, especially in rainy and snowy weather, extreme low temperature and repeated freeze-thaw cycle conditions, its performance may be affected. Under these conditions, the integrity of the subgrade structure and function may be damaged, leading to cracks, settlement or other subgrade diseases. Especially in winter, freeze-thaw cycle can cause micro-damage to lightweight filler structure, which in turn affects its macro performance.

[0018] Insufficient ability to quickly open:

[0019] When the subgrade is subjected to devastating damage such as collapse, washout, submersion, etc., due to the special structure and material properties of lightweight filler subgrade, its ability to quickly open and repair is relatively weak. This type of subgrade structure requires precise material matching and construction technology, and once damaged, the repair process may be both complex and time-consuming, affecting the rapid recovery of the road for use.

[0020] In summary, although these two types of lightweight filler subgrade structures perform well in many ways, there are still a series of challenges and limitations in their practical application. SUMMARY

[0021] The purpose of the present invention is to provide a shock-absorbing lightweight filler for rapid assembly block-type railway subgrade structure. This shock-absorbing lightweight filler focuses on the scientific configuration of the internal filler and the layered design of the shock-absorbing lightweight filler subgrade. The first layer of the rapid assembly block-type railway subgrade is filled with hollow glass microsphere lightweight filler, and the second / third layer is filled with solid waste collaborative lightweight filler. In this structure, the use of hollow glass microspheres is a key innovation. The uniform distribution of hollow glass microspheres in lightweight filler can effectively absorb and disperse these vibration waves, thereby reducing the impact on the railway subgrade, prolonging the service life of the subgrade, and providing a smoother ride experience for train passengers. In addition, this design method also takes into account environmental sustainability. The use of hollow glass microspheres, rubber particles and fly ash not only improves the performance of the material, but also is an environmentally friendly choice, as these materials can be recycled and reused from waste glass materials, tires and slag, thereby reducing the burden on the environment.

[0022] The technical solution disclosed by the present invention is as follows:

[0023] A preparation method of a shock-absorbing lightweight filler, characterized by:

[0024] Step 1: raw materials and proportioning

[0025] The liquid foaming agent comprises silicate cement, fly ash, hollow glass microbeads, polycarboxylic acid water reducer, alkali metal salt of alkyl sulfonic acid and hydrolyzed protein, and is composed of the raw materials in a mass ratio.

[0026] Step 2: preparation process of the lightweight filler, comprising: dilution and foaming of the foaming agent; mixing and stirring; molding and curing;

[0027] Step 3: design of the unit weight of the lightweight filler

[0028] The total volume of the mixed dry material, the total volume of the required water and the mass of the lightweight filler foam are accurately calculated, and the design density of the lightweight filler is determined.

[0029] The application further discloses an assembled base block type railway roadbed structure, characterized in that the railway roadbed structure comprises, from top to bottom, a waterproof layer, an assembled base block type railway roadbed and a foundation; the assembled base block type railway roadbed is arranged above the foundation and is provided with a waterproof layer formed by pouring asphalt concrete; and the railway roadbed is composed of base blocks made of the above-mentioned vibration-damping type lightweight filler.

[0030] The application further discloses a railway roadbed, characterized in that the railway roadbed is composed of the above-mentioned assembled base block type railway roadbed structure, and the base block structure is in the form of a cuboid or a square.

[0031] The application further discloses a laying method of a railway roadbed, and the railway roadbed is the above-mentioned railway roadbed, characterized in that the method comprises the following steps.

[0032] Laying of the bottom layer base blocks:

[0033] The third design unit weight base block is used; the corresponding hoisting device is used to lay the bottom layer base blocks one by one or simultaneously in the line direction; the third design unit weight base block is used for the bottom layer base blocks; when the bottom layer base blocks are laid, the flatness and stability of the base blocks are paid attention to, so that each base block is correctly placed and aligned; after the bottom layer base blocks are laid for a certain distance, the middle layer base blocks are laid;

[0034] Laying of the middle layer base blocks:

[0035] The second design unit weight base block is used for the middle layer base blocks; the hoisting device is used to place the pre-assembled middle layer base blocks on the bottom layer base blocks in sequence according to the same number of the bottom layer base blocks; during the laying process, the lower concave table of the middle layer base blocks is ensured to be correctly embedded with the upper convex table of the bottom layer base blocks; after the middle layer base blocks are laid, the upper layer base blocks are continuously laid in the same way;

[0036] Laying of the upper layer base blocks:

[0037] The upper base block uses the first design to assemble the bottom, middle and upper base blocks in a predetermined order and method; the assembled section of roadbed is connected to the previously laid roadbed section using a lifting device, with the base blocks fitting together in a concave-convex manner.

[0038] The assembly of the overall roadbed is complete:

[0039] Repeat the above steps until the entire railway roadbed is laid; during the laying process, continuously check the fitting quality and stability of each layer of base blocks to ensure the uniformity and continuity of the entire railway roadbed.

[0040] Advantages

[0041] 1. Quick repair and emergency response: The addition of hollow glass microbeads makes lightweight fillers more easily and quickly laid and cured in emergency situations, which is particularly important for repairing railway roadbeds or emergency response in disaster situations.

[0042] 2. Adapt to extreme environments: The addition of hollow glass microbeads improves the stability of lightweight fillers under extreme temperature and humidity conditions, making them more suitable for use in variable environmental conditions.

[0043] 3. Improve structural stability: The addition of hollow glass microbeads can increase the overall stability of lightweight fillers. This stability is crucial for high-speed railway roadbeds, especially when subjected to the vibration and impact of high-speed trains for a long time.

[0044] 4. Enhance durability: Hollow glass microbeads have properties such as chemical corrosion resistance and wear resistance, which make lightweight fillers with this material have better long-term durability. For railway roadbeds, this means less maintenance and longer service life.

[0045] 5. Improve thermal and sound insulation performance: Hollow glass microbeads have good thermal and sound insulation properties, which are particularly important for improving the environmental quality along the railway and reducing noise pollution.

[0046] 6. Balance of lightweight and high strength: The addition of hollow glass microbeads improves the compressive strength of lightweight fillers while maintaining their lightweight properties. This is particularly important for railway roadbeds that need to bear heavy trains.

[0047] 7. Environmentally friendly: Hollow glass microbeads as an environmentally friendly material, its application meets the current demand for sustainable construction. The use of this material helps to reduce the impact on the environment, while improving the overall sustainability of railway construction projects. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Sectional view of the assembled base block type railway roadbed structure with rectangular and cubic configurations

[0049] The subgrade consists of three layers: 1-foundation, 1-1-foundation section length 40m, 1-2-foundation width 30m, 1-3-foundation section height 5m; 2-three-layer prefabricated block-type railway subgrade, 2-1-top layer block, 2-2-middle layer block, 2-3-base layer block; and 3-waterproof layer. Rectangular and square components do not affect the selection of fill material; the fill material is only related to the layer level. Specifically, 2-1-top layer block uses the first design density block, 2-2-middle layer block uses the second design density block, and 2-3-base layer block uses the third design density block. Detailed Implementation

[0050] To achieve the above objectives, the vibration-damping lightweight filler for the prefabricated block-type railway subgrade structure filler of the present invention adopts the following technical solution:

[0051] A method for preparing vibration-damping lightweight filler for prefabricated modular railway subgrade structures is disclosed. This method, through specific raw material ratios and production processes, aims to achieve efficient and stable vibration reduction effects and ensure the long-term durability of the railway subgrade structure. The following is a detailed description of the technical solution of this invention:

[0052] I. Raw Material and Proportioning Design

[0053] (1): The raw materials include ordinary silicate cement (strength grade 42.5), fly ash, 15-85μm hollow glass microspheres, polycarboxylate superplasticizer (water reduction rate greater than 20%), and liquid foaming agent composed of alkali metal salts of alkyl sulfonates and hydrolyzed proteins in a mass ratio of 0.2%-0.4%.

[0054] (2): The raw material weighing covers silicate cement, hollow glass microspheres and water to ensure that each component is accurately configured as required.

[0055] II. Preparation process of lightweight filler

[0056] 1. Dilution and foaming of the foaming agent: Using type A01 foaming agent, mix it with water at the optimal dilution ratio and then pour it into the storage tank. Pressurize it to 0.5MPa using an air compressor, control the mixing ratio of the foaming agent and air, and generate foam of ideal density.

[0057] 2. Mixing: Put the proportioned cement into the mixing pot and stir for 2 minutes. Then add the dissolved water-reducing agent and water, and continue stirring for 3-5 minutes. Next, add the pre-made foam and stir until the foam and slurry are evenly mixed.

[0058] 3. Molding and curing: The mixed foamed lightweight soil is poured into specimens, covered with a film, and then transferred to a curing room (temperature controlled at 20±2.0℃) for natural curing until the strength required for demolding is reached.

[0059] III. Lightweight Packing Material Bulk Density Design

[0060] The total volume of the mixed dry materials, the total volume of water required, and 1m³ 3 Precise calculation of the mass of lightweight filler foam, and determination of the design density of lightweight filler.

[0061] Bulk density design of lightweight packing materials:

[0062] (1) Calculate the total volume of the mixed dry materials

[0063] (2) Calculate the total volume of water required.

[0064] (3) Calculate 1m 3 The foam quality method for lightweight fillers is as follows:

[0065]

[0066] (4) Calculate the bulk density of the lightweight filler.

[0067] ρ s =S a m c

[0068] m w =Bm c

[0069] ρ s —Design density of lightweight filler;

[0070] S a --The mass determined by the total dry material and the total non-evaporated matter of the product after the specified curing period for lightweight fillers.

[0071] The coefficient is 1.2 for ordinary Portland cement;

[0072] m c —Cement weight (kg);

[0073] m w —The mass of water (kg);

[0074] B—Water-to-binder ratio.

[0075] IV. Design of Prefabricated Modular Railway Subgrade Structure

[0076] The railway subgrade structure of the present application comprises, from top to bottom, a waterproof layer, an assembled base block type railway subgrade, and a foundation. The assembled base block type railway subgrade is located above the foundation, and a waterproof layer made of poured asphalt concrete is provided above it. The railway subgrade is composed of base blocks made of foam lightweight soil material prefabricated in a factory, and the base block structure can be in the form of a cuboid or a cube. The assembled base block type railway subgrade uses a simple and fast single-point mortise and tenon joint connection method, i.e., the base blocks are directly fitted and connected as a whole without the need for additional processing.

[0077] Through this series of carefully designed process flows and structural designs, the vibration-reducing lightweight filler of the present application not only provides the advantages of light weight and high vibration reduction in the railway subgrade structure, but also greatly improves the construction efficiency and structural stability through the design of assembled base blocks. In addition, considering the environmental impact and cost effectiveness, the present application provides an economical and environmentally friendly railway infrastructure construction solution. Through precise proportioning of materials, strict control of the preparation process, and meticulous maintenance and performance testing, the present application can effectively improve the overall performance of the railway subgrade, providing an innovative technical solution for modern railway construction.

[0078] The present embodiment provides three types of vibration-reducing lightweight fillers, each comprising the following raw materials in weight fractions: The first design has a bulk density of 800 (Kg / m 3 ) and is composed of the following mass fractions: cement 600-616 (kg / m 3 ), hollow glass microbeads 49-50 (kg / m 3 ), water 308 (kg / m 3 ), foaming agent 12-18 (g / m 3 ), water reducing agent 30-40 (g / m 3 ), and foam 1.746 (m 3 / m 3 ).

[0079] The second design has a bulk density of 400 (Kg / m 3 ) and is composed of the following mass fractions: cement 316 (kg / m 3 ), rubber particles 16 (kg / m 3 ), water 166 (kg / m 3 ), foam 0.873 (m 3 / m 3 ), foaming agent 6-9 (g / m 3 ), and water reducing agent 15-20 (g / m 3 ).

[0080] The third design has a bulk density of 400 (Kg / m 3 ) and is composed of the following mass fractions: cement 266 (kg / m 3 ), fly ash 67 (kg / m 3), water 133 (kg / m 3 ), foam 0.873 (m 3 / m 3 ), foaming agent 10-15 (g / m 3 ), water-reducing agent 25-35 (g / m 3 ).

[0081] The following requirements are made for the base block mold:

[0082] After the pouring of the test piece is completed, cover the film, move the test piece into the curing room (20 ± 2.0℃) for natural curing, and then remove the mold when the strength reaches the removal requirement.

[0083] The laying method of the assembled base block type railway subgrade structure involves using precast base blocks with different unit weights and specific laying sequences and methods to achieve efficient assembly and stability of the railway subgrade structure. The detailed construction steps for laying precast base blocks are as follows:

[0084] Laying of the bottom layer base blocks:

[0085] Use the corresponding lifting device to lay the bottom layer base blocks individually or simultaneously in multiple numbers along the line direction. The bottom layer base blocks use the third design unit weight base blocks, which have high stability and carrying capacity. When laying the bottom layer base blocks, pay attention to the flatness and stability of the base blocks to ensure correct placement and alignment of each base block. After laying a certain distance of bottom layer base blocks, start laying the middle layer base blocks.

[0086] Laying of the middle layer base blocks:

[0087] The middle layer base blocks use the second design unit weight base blocks, which strike a balance between light weight and strength. Use the lifting device to place the pre-assembled middle layer base blocks on top of the bottom layer base blocks in the same number as the bottom layer base blocks. During the laying process, ensure that the lower recesses of the middle layer base blocks correctly fit into the upper protrusions of the bottom layer base blocks to ensure the tight connection and overall stability of the structure. After completing the laying of the middle layer base blocks, continue to lay the upper layer base blocks in the same way.

[0088] Laying of the upper layer base blocks:

[0089] The upper layer base blocks use the first design unit weight base blocks, which usually have lighter weight for easy laying and adjustment. Assemble the bottom layer, middle layer, and upper layer base blocks according to the predetermined sequence and method. Use the lifting device to connect the assembled section of the subgrade with the previously laid subgrade section in the way of recess-protrusion fitting of the base blocks.

[0090] Completion of the assembly of the overall subgrade:

[0091] The above steps are repeated until the entire railway subgrade is laid. During the laying process, the quality of the embedding and stability of each layer of base blocks are constantly checked to ensure the uniformity and continuity of the entire railway subgrade.

[0092] Through the above steps, the assembled base block railway subgrade structure of the present application can be efficiently assembled while ensuring the stability and durability of the structure. This laying method not only improves the construction efficiency, but also reduces the construction cost and time. In addition, this method provides a flexible construction scheme suitable for different types of railway infrastructure construction, especially in complex terrain or situations requiring rapid construction. Through precise design and strict construction management, the long-term stability and reliability of the railway subgrade can be ensured, providing an innovative technical solution for modern railway construction.

[0093] The addition of hollow glass microspheres in the application of lightweight fillers plays a positive role in many aspects, especially in the construction and maintenance of railway subgrades. First of all, the lightweight nature of this material makes it easier to quickly lay and solidify lightweight fillers in emergency situations such as disaster response or rapid repair. This is particularly important for maintaining the integrity and functionality of the railway subgrade in emergency situations. At the same time, hollow glass microspheres also improve the stability of concrete under extreme temperature and humidity conditions, making it more suitable for dealing with changing environmental conditions, which is particularly important for railway construction and maintenance in complex climates.

[0094] In addition, hollow glass microspheres also have a positive impact on the structural stability and durability of lightweight fillers. Lightweight fillers with the addition of this material exhibit higher stability under the long-term vibration and impact of high-speed trains, which is crucial for the safety and reliability of high-speed railway subgrades. In addition, the chemical corrosion resistance and wear resistance of hollow glass microspheres provide lightweight fillers with longer service life and less maintenance requirements, which is a great advantage for long-term railway subgrade maintenance and economic benefits.

[0095] Finally, the application of hollow glass microspheres also helps to improve the thermal and acoustic insulation performance of lightweight fillers, which is very important for improving the environmental quality along the railway and reducing noise pollution. At the same time, as an environmentally friendly material, the application of hollow glass microspheres in railway construction meets the current demand for sustainable development, helping to reduce the environmental impact of construction projects. By adding hollow glass microspheres to lightweight fillers, a balance between lightweight and high strength can be achieved, which is crucial for railway subgrades carrying heavy trains, while also improving the environmental friendliness and sustainability of the entire railway construction project.

[0096] The application proposes a new type of damping light filler applied to the rapid assembly type railway subgrade structure base block. This damping light filler mainly focuses on realizing effective absorption and mitigation of railway operation vibration through scientific configuration of internal filler. In this structure, the use of hollow glass microbeads is a key innovation point. These microbeads have unique structural characteristics, i.e. specific hollow nature on the micro level, which can provide excellent damping function for the light filler. The light weight characteristics of hollow glass microbeads not only reduce the overall structure weight, but also bring better elasticity and compression resilience to the light filler due to the existence of internal cavities. The above advantages show that the use of hollow glass microbeads can reduce the performance loss of the material under dynamic load, and provides a new idea for the performance optimization design of the subgrade material and the performance improvement of the structure.

[0097] In summary, the design method of the damping light filler in the assembly type subgrade structure of the application can not only improve the damping performance of the material by introducing hollow glass microbeads as the key filler, but also considers the economy and environmental sustainability, and provides an innovative and practical solution for the high-quality green and sustainable development of modern railway engineering.

[0098] The above shows and describes the basic principles, main features and advantages of the application. It should be understood by those skilled in the art that the application is not limited by the above examples, and the above examples and descriptions in the specification are only the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection required by the application is defined by the appended claims and their equivalents.

Claims

1. A method for laying railway subgrade, characterized in that, Includes the following steps: Laying out the bottom layer blocks: The third type of density base blocks are used; the corresponding hoisting equipment is used to lay the bottom layer base blocks one or more at the same time along the line direction; the bottom layer base blocks are the third type of density base blocks; when laying the bottom layer base blocks, attention should be paid to the flatness and stability of the base blocks to ensure that each base block is correctly placed and aligned; after laying a certain distance of bottom layer base blocks, the middle layer base blocks are laid. Laying of intermediate base blocks: The middle layer base blocks adopt the second type of density base blocks. Using a hoisting device, the pre-assembled middle layer base blocks are placed on the bottom base blocks in the same number as the bottom base blocks. During the laying process, ensure that the concave platform on the lower side of the middle layer base blocks and the convex platform on the upper side of the bottom base blocks are correctly engaged. After the middle layer base blocks are laid, continue to lay the upper base blocks in the same way. Laying of the upper base blocks: The upper layer uses the first type of design density base block. The bottom, middle and upper layers of base blocks are assembled in a predetermined order and method. A hoisting device is used to connect the assembled section of roadbed to the previously laid roadbed section in a way that the base blocks fit together in a front-to-back concave-convex manner. The overall roadbed assembly is complete: Repeat the above steps until the entire railway subgrade is laid; during the laying process, continuously check the fitting quality and stability of each layer of base blocks to ensure the uniformity and continuity of the entire railway subgrade. Vibration-damping lightweight filler, comprising the following raw materials by weight fraction: First design bulk density base block 800kg / m³ 3 It consists of the following components by weight: cement 600~616kg / m³ 3 Hollow glass microspheres 49-50 kg / m 3 Water 308kg / m 3 Foaming agent 12-18g / m³ 3 Water-reducing agent 30-40g / m 3 Foam 1.746m 3 / m 3 ; The second design uses a substrate block of 400 kg / m³. 3 It consists of the following components by weight: cement 316 kg / m³ 3 16kg / m of rubber granules 3 Water 166kg / m 3 Foam 0.873m 3 Foaming agent 6-9g / m³ 3 Water-reducing agent 15-20g / m³ 3 ; The third design uses a bulk density base of 400 kg / m³. 3 It consists of the following components by weight: cement 266 kg / m³ 3 fly ash 67kg / m³ 3 Water 133kg / m 3 Foam 0.873m 3 Foaming agent 10-15g / m³ 3 Water-reducing agent 25-35g / m³ 3 ; The railway subgrade is composed of prefabricated modular railway subgrade structures, and the structural form of the prefabricated modular blocks is cuboid or cubic; adjacent prefabricated modular blocks are connected by a single-point mortise and tenon joint. The prefabricated modular railway subgrade structure comprises, from top to bottom, a waterproof layer, a prefabricated modular railway subgrade, and a foundation; the prefabricated modular railway subgrade is located above the foundation, and a waterproof layer made of asphalt concrete is provided on top; the railway subgrade is composed of modules made by a prefabricated method for preparing vibration-damping lightweight filler. The preparation method of vibration-damping lightweight filler includes the following steps: Step 1: Raw materials and proportions: A liquid foaming agent composed of silicate cement, fly ash, hollow glass microspheres, polycarboxylate superplasticizer, alkali metal salts of alkyl sulfonates, and hydrolyzed proteins in a mass ratio; Step 2: The preparation process of lightweight filler, including dilution and foaming of the foaming agent; mixing and stirring; molding and curing; Step 3: Lightweight filler density design: Accurately calculate the total volume of the mixed dry material, the total volume of water required, and the foam mass of the lightweight filler, as well as determine the design density of the lightweight filler.

2. The method for laying railway subgrade according to claim 1, characterized in that: The silicate cement has a strength grade of 42.

5. It is composed of fly ash, 15-85μm hollow glass microspheres, polycarboxylate superplasticizer with a water reduction rate of more than 20%, and liquid foaming agent composed of alkali metal salt of alkyl sulfonate and hydrolyzed protein in a mass ratio of 0.2% to 0.4%.

3. The method for laying railway subgrade according to claim 1, characterized in that: The dilution and foaming process of the foaming agent is as follows: A01 type foaming agent is mixed with water according to the dilution ratio and then put into a storage tank; the air is pressurized to 0.5MPa by an air compressor to control the mixing ratio of the foaming agent and air, and foam of ideal density is generated.

4. The method for laying railway subgrade according to claim 3, characterized in that: The mixing process is as follows: put the proportioned cement into a mixing pot and stir for 2 minutes, then add the dissolved water-reducing agent and water, and continue stirring for 3-5 minutes; then add the pre-made foam and stir until the foam and slurry are evenly mixed.

5. The method for laying railway subgrade according to claim 4, characterized in that: The molding and curing process involves: pouring the mixed foamed lightweight soil into specimens, covering them with a film, transferring them to a curing room, controlling the temperature at 20±2.0℃, and allowing them to cure naturally until they reach the strength required for demolding.

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