A permeable shock-absorbing and frost-proof lightweight soil material and structural type

Abstract

The present invention belongs to the technical field of tunnel engineering, and particularly relates to a water-permeable, shock-absorbing, and anti-freezing lightweight soil material and a structural type. The water-permeable, shock-absorbing, and anti-freezing lightweight soil material prepared by the present invention is composed of cement, fine sand, foam, carbon fiber, water-absorbing resin, and thickener, and contains a large number of pore structures inside. The material realizes the conductive and heat-generating function through carbon fiber, which can prevent water from accumulating and freezing in the drainage channels and entrance and exit areas inside the tunnel under low temperature conditions; the porous structure of the material gives it lightness and excellent water permeability, which can quickly drain the accumulated water in the tunnel structure; in addition, this porous characteristic enables it to effectively absorb and disperse vibration energy under the action of traffic dynamic loads, thereby improving the seismic performance of the tunnel. This innovative material has significant advantages in water permeability, shock absorption, and anti-freezing, and provides reliable protection for the long-term stability and safety of the tunnel structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel engineering, and in particular relates to a water-permeable, shock-absorbing and anti-freezing lightweight soil material and a structural type. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] With the rapid advancement of tunnel construction, tunnel construction is gradually extending into complex geological conditions and variable hydrological environments. In these projects, seasonal fluctuations in groundwater levels and the long-term effects of traffic dynamic loads often have a significant impact on tunnel structures. Periodic changes in water levels can cause fatigue damage at tunnel segment interfaces, leading to leakage problems. At the same time, the vibrations generated by traffic dynamic loads, when transmitted to the surrounding soil, may cause local soil liquefaction, increasing the risk of tunnel structure stability. In addition, winter temperatures at tunnel entrances and exits in northern China are below zero degrees Celsius, making snow and ice accumulation prone to damage structural components.

[0004] To address these issues, researchers have proposed a series of technical solutions encompassing drainage design, vibration-damping materials, and antifreeze technologies. However, these solutions often focus on addressing a single technical issue within soil tunnels, failing to meet the long-term safety requirements inherent in complex hydrogeological and climatic conditions, coupled with traffic loads. Therefore, it is necessary to develop a new tunnel filling material that combines drainage, vibration-damping, and antifreeze properties. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a permeable, shock-absorbing and anti-freezing lightweight soil material and structural type. The filling material prepared by the present invention has the functions of permeability, shock absorption and anti-freezing, and can be used in the tunnel filling ditch area. It can achieve efficient drainage and effectively alleviate traffic accidents caused by interface leakage and water accumulation; effectively absorb and disperse vibration energy, reduce vehicle vibration-induced tunnel structure fatigue damage and soil liquefaction and other diseases; built-in heating pipes can avoid problems such as filling ditch drainage failure caused by freezing in winter.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A first aspect of the present invention provides a permeable shock-absorbing and anti-freezing lightweight soil material, the raw material composition of which includes, by weight: 20.20 to 47.19 parts of cement, 3.37 to 20.93 parts of fine sand, 1.6 to 3.73 parts of foam, 0.04 to 0.43 parts of carbon fiber, 0.27 to 1.59 parts of water-absorbing resin, 0.02 to 0.05 parts of thickener, and 8.76 to 22.28 parts of water.

[0008] Preferably, the cement is selected from one or more of ordinary Portland cement, white cement, aluminate cement, blast furnace slag cement, a mixture of Portland cement and mineral powder, and quick-setting cement.

[0009] Preferably, the fine sand is selected from one of natural fine sand, artificial fine sand and river sand, and has a particle size of 0.075-1 mm, more preferably 0.2-0.6 mm.

[0010] Preferably, the foam is produced by physical foaming in a foaming machine through an air compressor, and the foam density is 42.5-65 kg / m 3 ; Further preferably, the foaming agent is selected from one or more of animal protein foaming agents, plant protein foaming agents and complex surfactants.

[0011] Preferably, the water-absorbing resin is selected from one or more of polyacrylic acid water-absorbing resins, polyvinyl alcohol water-absorbing resins, starch graft copolymer water-absorbing resins, cellulose-based water-absorbing resins, natural polymer water-absorbing resins and organic-inorganic composite water-absorbing resins.

[0012] Preferably, the thickener is selected from one or more of carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose (HPMC) and methyl cellulose (MC).

[0013] The second aspect of the present invention provides a method for preparing the above-mentioned permeable shock-absorbing and anti-freezing lightweight soil material, which is specifically: first, the water-absorbing resin absorbs water to a gel state to obtain a water-absorbing resin gel, and the foam is whipped, and then water, cement, fine sand and carbon fiber are mixed and stirred until the slurry is uniform to obtain a cement slurry, the water-absorbing resin gel is added to the cement slurry to obtain a uniform slurry, and finally the whipped foam and thickener are added to the slurry and stirred to obtain a mixture, which is the permeable shock-absorbing and anti-freezing lightweight soil material.

[0014] Preferably, the preparation process of the cement slurry is carried out by stirring at 300-400 r / min for 60-120 s; further preferably, the preparation process of the cement slurry is carried out by stirring at 360 r / min for 90 s.

[0015] Preferably, the preparation process of the uniform slurry is carried out by stirring at 100-200 r / min for 30-90 s; further preferably, the preparation process of the cement slurry is carried out by stirring at 180 r / min for 60 s.

[0016] Preferably, the mixture is prepared by stirring at 100-200 r / min for 30-90 s; further preferably, the cement slurry is prepared by stirring at 180 r / min for 60 s.

[0017] The third aspect of the present invention provides an application of the above-mentioned permeable shock-absorbing and anti-freezing lightweight soil material in the field of tunnels and underground engineering.

[0018] The fourth aspect of the present invention provides a high-efficiency drainage structure for tunnels, comprising the permeable shock-absorbing and antifreeze lightweight soil material described in the first aspect, wherein the permeable shock-absorbing and antifreeze lightweight soil material is filled in the filling ditch of the high-efficiency drainage structure for tunnels.

[0019] Preferably, the high-efficiency drainage structure for the tunnel further includes a longitudinal drainage pipe, a water collection ditch, a filling ditch and a filter screen;

[0020] Among them, the longitudinal drainage pipe is arranged on the surrounding rock of the arch wall on both sides of the tunnel; the water collection ditch is arranged between the tunnel invert arch and the track; the filling ditch is arranged between the water collection ditch and the tunnel arch foot, and is symmetrically arranged on both sides of the water collection ditch; the filter is arranged at the connection between the roads on both sides of the track, the filling ditch and the surrounding rock of the arch wall on both sides.

[0021] Preferably, the tunnel high-efficiency drainage structure is arranged in the tunnel within a range of ≥50 m from the entrance.

[0022] It is further preferred that heating rods are evenly laid every 0.5 to 1 m in the filling ditch within the tunnel entrance and poured into the foam lightweight soil. Electric heating can effectively prevent water accumulation and freezing in the filling ditch, thereby ensuring the smooth flow and safety of the tunnel drainage channel and driving road.

[0023] Further preferably, the heating rods are arranged in a regular array in the plane of the filling groove, specifically in two rows with longitudinal spacing; the heating rods are evenly spaced in the row (transverse) and column (longitudinal) directions and meet the design requirement of a spacing of 0.5 to 1 meter.

[0024] Further preferably, when the temperature is below 0°C, the power supply device can be turned on to quickly heat the filled permeable shock-absorbing and antifreeze lightweight soil material.

[0025] Preferably, the outside of the tunnel surrounding rock where the longitudinal drainage pipe is located also includes a cast-in-place base and anti-backward push stones.

[0026] Preferably, the length of the filter is 0.8 to 1.2 m, preferably 1 m. After the surface water on the road is initially filtered through the filter, it seeps into the filling ditch and is discharged into the collection ditch.

[0027] Further preferably, the filter screen is made of a corrosion-resistant, wear-resistant high-strength material, and the filter screen aperture is set at 0.5~2 mm.

[0028] Further preferably, drainage holes are provided on both sides of the ditch every 1.5 to 2 m along the track direction, with a diameter of 8 to 10 cm, and are arranged at intervals up and down along the side walls of the ditch to enhance drainage efficiency and ensure that accumulated water in the permeable shock-absorbing and antifreeze lightweight soil material can quickly flow into the ditch.

[0029] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0030] (1) The permeable, shock-absorbing, and anti-freezing lightweight soil material provided by the present invention can effectively absorb and disperse vibration energy under the action of traffic dynamic loads, thereby preventing the tunnel structure from being subjected to fatigue damage caused by dynamic load impacts and reducing the risk of liquefaction of the surrounding soil.

[0031] (2) The permeable shock-absorbing and anti-freezing lightweight soil material provided in this application has excellent water permeability and can quickly drain the accumulated water in the tunnel, preventing the long-term damage to the tunnel caused by water pressure accumulation and ensuring traffic safety.

[0032] (3) The permeable, shock-absorbing and anti-freezing lightweight soil material provided by the present invention can effectively prevent water from accumulating and freezing in a low-temperature environment, thereby ensuring the smooth flow of the drainage system under low-temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the high-efficiency drainage structure for tunnels designed for the present invention;

[0034] Figure 2 It is a schematic diagram of the arrangement of drainage holes of the present invention.

[0035] Among them, 101-cast-in-place base; 102-anti-rockfall prevention; 103-longitudinal drainage pipe; 104-drainage ditch; 105-filling ditch; 106-filter; 107-drainage hole; 108-drainage ditch side wall; 109-heating rod. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise clearly indicated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprising" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations;

[0038] Explanation of terms: The terms "connected", "connected", etc. in the present invention should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection, a direct connection, or an indirect connection through an intermediate medium, an internal connection between two elements, or an interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] As mentioned above, existing technical solutions often focus on solving a single technical problem in soil tunnels, failing to meet the long-term safety requirements under the complex hydrogeological and climatic conditions and the coupled effects of traffic dynamic loads. Therefore, this paper proposes a new tunnel filling material that combines drainage, shock absorption, and antifreeze functions, and also designs the tunnel structure accordingly.

[0040] The first typical embodiment of the present invention provides a permeable shock-absorbing and anti-freezing lightweight soil material, whose raw material composition includes, by weight: 20.20~47.19 parts of cement, 3.37~20.93 parts of fine sand, 1.6~3.73 parts of foam, 0.04~0.43 parts of carbon fiber, 0.27~1.59 parts of water-absorbing resin, 0.02~0.05 parts of thickener, and 8.76~22.28 parts of water.

[0041] In one or more examples of this embodiment, the cement is selected from one or more of ordinary Portland cement, white cement, aluminate cement, blast furnace slag cement, a mixture of Portland cement and mineral powder, and quick-setting cement.

[0042] In one or more examples of this embodiment, the fine sand is selected from one of natural fine sand, artificial fine sand and river sand, and has a particle size of 0.075-1 mm, more preferably 0.2-0.6 mm.

[0043] In one or more embodiments of this embodiment, the foam is produced by physical foaming in a foaming machine through an air compressor, and the foam density is 42.5-65 kg / m 3 ; Further preferably, the foaming agent is selected from one or more of animal protein foaming agents, plant protein foaming agents and complex surfactants.

[0044] In one or more examples of this embodiment, the water-absorbing resin is selected from one or more of polyacrylic acid water-absorbing resins, polyvinyl alcohol water-absorbing resins, starch graft copolymer water-absorbing resins, cellulose-based water-absorbing resins, natural polymer water-absorbing resins and organic-inorganic composite water-absorbing resins.

[0045] In one or more examples of this embodiment, the thickener is selected from one or more of carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose (HPMC) and methyl cellulose (MC).

[0046] The second typical embodiment of the present invention provides a preparation method for the above-mentioned permeable shock-absorbing and anti-freezing lightweight soil material, which is specifically: first, the water-absorbing resin absorbs water to a gel state to obtain a water-absorbing resin gel, and the foam is whipped, and then water, cement, fine sand and carbon fiber are mixed and stirred until the slurry is uniform to obtain a cement slurry, and the water-absorbing resin gel is added to the cement slurry to obtain a uniform slurry, and finally the whipped foam and thickener are added to the slurry and stirred to obtain a mixture, which is the permeable shock-absorbing and anti-freezing lightweight soil material.

[0047] In one or more examples of this embodiment, the cement slurry is prepared by stirring at 300-400 r / min for 60-120 s.

[0048] In one or more examples of this embodiment, the uniform slurry is prepared by stirring at 100-200 r / min for 30-90 s.

[0049] In one or more examples of this embodiment, the mixture is prepared by stirring at 100-200 r / min for 30-90 s.

[0050] A third typical embodiment of the present invention provides an application of the above-mentioned permeable shock-absorbing and anti-freezing lightweight soil material in the field of tunnels and underground engineering.

[0051] The fourth typical embodiment of the present invention provides a high-efficiency drainage structure for tunnels, comprising the above-mentioned permeable shock-absorbing and antifreeze lightweight soil material, wherein the permeable shock-absorbing and antifreeze lightweight soil material is filled in the filling ditch of the high-efficiency drainage structure for tunnels.

[0052] In one or more embodiments of this embodiment, the high-efficiency drainage structure for tunnels further includes a longitudinal drainage pipe, a water collection ditch, a filling ditch, and a filter screen;

[0053] Among them, the longitudinal drainage pipe is arranged on the surrounding rock of the arch wall on both sides of the tunnel; the water collection ditch is arranged between the tunnel invert arch and the track; the filling ditch is arranged between the water collection ditch and the tunnel arch foot, and is symmetrically arranged on both sides of the water collection ditch; the filter is arranged at the connection between the roads on both sides of the track, the filling ditch and the surrounding rock of the arch wall on both sides.

[0054] In one or more embodiments of this implementation mode, the tunnel high-efficiency drainage structure is arranged in the tunnel within a range of ≥50 m from the entrance.

[0055] In one or more embodiments of this implementation mode, heating rods are evenly laid every 0.5 to 1 m in the filling ditch within the tunnel entrance and poured into foam lightweight soil. Electric heating can effectively prevent water accumulation and freezing in the filling ditch, thereby ensuring the smooth flow and safety of the tunnel drainage channel and driving road.

[0056] In one or more embodiments of this embodiment, the heating rods are arranged in a regular array in the plane of the filling groove, specifically in two rows with longitudinal spacing; the heating rods are evenly spaced in the row (horizontal) and column (longitudinal) directions and meet the design requirement of a spacing of 0.5 to 1 meter.

[0057] In one or more embodiments of this implementation mode, when the air temperature is below 0°C, the power supply device can be turned on to quickly heat the filled permeable shock-absorbing and antifreeze lightweight soil material.

[0058] In one or more embodiments of this implementation mode, the outer side of the tunnel surrounding rock where the longitudinal drainage pipe is located also includes a cast-in-place base and anti-backward push stones.

[0059] In one or more embodiments of this implementation mode, the length of the filter screen is 0.8~1.2 m, preferably 1 m. After the surface water on the road is initially filtered through the filter screen, it seeps into the filling ditch and is discharged into the collection ditch.

[0060] In one or more examples of this implementation mode, the filter screen is made of a high-strength material that is corrosion-resistant and wear-resistant, and the filter screen aperture is set to 0.5-2 mm.

[0061] In one or more embodiments of this implementation, drainage holes are set every 1.5~2 m on both sides of the ditch along the track direction. The diameter of the drainage holes is 8~10 cm and they are arranged at intervals up and down along the side walls of the ditch to enhance drainage efficiency and ensure that the accumulated water in the permeable shock-absorbing and anti-freezing lightweight soil material can quickly flow into the ditch.

[0062] In one or more embodiments of this implementation mode, the water-based shock-absorbing and anti-freezing lightweight soil material is paved by cast-in-place. First, cement, fine sand, water, foam, carbon fiber, water-absorbing resin and thickener are fully mixed in proportion to form a uniform slurry. The slurry is then poured directly into the tunnel filling ditch or entrance and exit paving area to tightly combine the material with the structural foundation. After pouring, wet curing is carried out, and the general curing period is 7-10 days.

[0063] Raw materials and functions:

[0064] Water-absorbent resin: During the material preparation stage, the water-absorbent resin absorbs water and expands. During the hydration and molding phase, it releases water to promote the hydration reaction, reducing its volume. This process leaves large cavities within the material, creating a rich pore structure that helps enhance the material's water permeability and shock absorption. Furthermore, the water-absorbent resin exhibits water-swelling properties and low-temperature stability, absorbing and retaining water and slowing its freezing rate. Furthermore, after absorbing water and expanding, the water-absorbent resin forms a gel, enhancing its elasticity. When subjected to traffic dynamic loads, the water-absorbent resin effectively disperses and blocks the propagation of vibration energy.

[0065] Foam: Foam provides the material with a large amount of pore structure, which can effectively reduce the density of the material and increase its water permeability, allowing moisture to be quickly removed.

[0066] Carbon fiber: When carbon fiber is combined with other components as a reinforcing material, the connectivity of the pores within the material will be increased by overlapping each other, forming a water-permeable connection channel and improving the water permeability effect; at the same time, carbon fiber has high tensile strength and elastic modulus, which can significantly improve the overall mechanical properties of the material, and form a microscopic elastic response area within the material, which can absorb and convert part of the vibration energy into internal heat, thereby reducing the transmission efficiency of vibration to the tunnel structure; in addition, carbon fiber has good electrical and thermal conductivity, which can quickly transfer the heat of the heating pipe to the surrounding material, and then use the conducted heat to prevent moisture from freezing at the entrance and exit of the tunnel.

[0067] As described above, the permeable, shock-absorbing and anti-freezing lightweight soil material prepared by the present invention realizes the three major functions of water permeability, shock absorption and anti-freezing through the interaction of various components. The synergistic effect of various components in the material not only improves the overall performance of the material, but also enables it to have excellent adaptability and versatility under different environmental conditions, thereby providing long-term and stable guarantees for engineering applications such as tunnels. The proportions of the various components of the material can be adjusted according to the actual needs of the tunnel project to meet the water permeability and shock absorption requirements under different environmental conditions.

[0068] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0069] Examples 1 to 4: This example provides four types of permeable, shock-absorbing, and frost-proof lightweight soil materials. The raw material ratios are shown in Table 1. The preparation method includes the following steps:

[0070] 1) The water-absorbing resin is pre-absorbed to a gel state and foamed by a foaming machine;

[0071] 2) Pour water, cement, fine sand, and carbon fiber into a mixing bucket in sequence and stir with a handheld mixer at 360 r / min for 90 s until the slurry is uniform.

[0072] 3) Pour the prepared water-absorbing resin gel according to the weight proportions described in the first aspect into the stirred cement slurry, and stir with a handheld stirrer at 180 rpm for 60 seconds to form a uniform slurry;

[0073] 4) Add the whipped foam and thickener according to the weight proportions described in the first aspect, and stir thoroughly with a handheld blender at 180 rpm for 60 seconds to obtain the product.

[0074] The raw material ratios (parts by weight) of the lightweight soil materials prepared in specific Examples 1 to 4 are shown in Table 1:

[0075] Table 1

[0076]

[0077] Comparative Examples 1 to 21: This comparative example provides a series of permeable shock-absorbing and antifreeze lightweight soil materials. The proportions of the raw materials are shown in Table 2. The difference from Example 1 lies in the differences in components and parts, and the specific preparation methods are the same.

[0078] The raw material ratios (parts by weight) of the lightweight soil materials prepared in specific comparative examples 1 to 21 are shown in Table 2:

[0079] Table 2

[0080]

[0081] Example 5: This example provides a highly efficient drainage structure

[0082] like Figure 1As shown, the efficient drainage structure includes a longitudinal drainage pipe 103, a water collection ditch 104, a filling ditch 105, and a filter 106. The longitudinal drainage pipe 103 is installed on the surrounding rock of the tunnel arch wall on both sides; the water collection ditch 104 is installed between the tunnel invert arch and the track; the filling ditch 105 is installed between the water collection ditch 104 and the tunnel arch foot, and is filled with the permeable, shock-absorbing and anti-freezing lightweight soil material prepared in Examples 1 to 4 of the present invention. The filling ditch 105 is symmetrically arranged on both sides of the water collection ditch 104; and the filter 106 is installed at the junction of the road on both sides of the track, the filling ditch, and the surrounding rock of the arch wall on both sides.

[0083] When water accumulation or seepage occurs inside the tunnel, the seepage water around the tunnel is directly discharged into the collecting ditch 104 through the longitudinal drainage pipe 103; the water accumulated on both sides of the road can seep into the filling ditch 105 through the filter screen 106. Due to the excellent permeability of the permeable shock-absorbing and anti-freezing lightweight soil, the water can quickly enter the collecting ditch 104 through the filling ditch 105 and be discharged from the tunnel area in a centralized manner.

[0084] In the above solution, drainage holes 107 (such as 10 cm in diameter) are provided on the side walls 108 of the ditch 104 at intervals of 2 meters along the road direction. Figure 2 These drainage holes are arranged at intervals up and down the side wall of the ditch to ensure that the accumulated water can flow quickly into the ditch 104.

[0085] The filter screen 106 in this experimental example is set above the filling ditch 105 on both sides of the road at the tunnel pipe interface, which is used to efficiently collect and guide the surface water on the road. It can effectively filter out the mud and impurities in the water and prevent them from entering the permeable lightweight soil filling ditch, thereby ensuring the smooth flow of the drainage system.

[0086] The fill trench 105 in this experimental example exhibits excellent shock absorption properties. When subjected to traffic loads or other vibrations, it undergoes slight deformation and compression, effectively absorbing and dissipating vibration energy, preventing the direct transmission of shock waves to the tunnel structure and surrounding soil. Furthermore, the material's relative softness effectively cushions vibration impacts, reducing the risk of liquefaction in the tunnel structure and surrounding soil.

[0087] In this experimental example, the filling trench 105 can also generate heat through power, effectively preventing water from freezing and ensuring the smooth flow of the drainage system. Furthermore, heating rods 109 are placed within the filling trench 105 at the tunnel entrance and exit. The synergistic effect of the heating rods and the material further prevents ice from forming on the road surface and drainage channel in low-temperature environments, providing more reliable winter drainage and traffic safety for the tunnel structure.

[0088] In this solution, heating rods 109 are evenly spaced every 0.5 to 1 meter within the filling trench 105 within 50 meters of the tunnel entrance and exit. These rods, when electrically heated, raise the internal temperature of the material in low or icy conditions, effectively preventing water from accumulating and freezing. In snowy or icy weather, the heating rods work in conjunction with the self-heating, permeable, shock-absorbing, and antifreeze lightweight soil material to rapidly melt snow and ice, ensuring driving safety and reducing the risks associated with winter icing.

[0089] Test Example 1: Based on the high-efficiency drainage structure type for tunnels set in Example 5, this test example tests the relevant performance of the permeable, shock-absorbing and anti-freezing lightweight soil materials prepared in Examples 1 to 4 and Comparative Examples 1 to 21, as shown in Table 3:

[0090] Table 3

[0091]

[0092] From the data analysis in Table 3, we can get:

[0093] Compared to Example 1, Examples 2-4, while meeting basic industry requirements for water permeability, frost resistance, and shock absorption (lower dynamic modulus values ​​indicate better shock absorption) (according to the relevant requirements of the "Highway Subgrade Design Code," when foamed lightweight soil is used for roadbed filling, the compressive strength must be no less than 0.8 MPa), still lack the right balance of properties. Example 2 has lower water permeability, and its frost resistance and shock absorption performance are inferior to those of Example 1, but its compressive strength is enhanced. Example 3, while having higher water permeability, has significantly decreased shock absorption and compressive strength, failing to meet the engineering load requirements. Example 4 only meets basic frost resistance requirements, while water permeability, shock absorption, and strength are all reduced. Therefore, the components and amounts added in Example 1 are optimally controlled, achieving simultaneously high water permeability, high frost resistance, high shock absorption, and high compressive strength. In contrast, the modifications in Examples 2-4, while improving some properties, often lead to degradation of others, demonstrating that the ratios of the components must be precisely controlled to meet the comprehensive material performance requirements under complex working conditions. (2) Compared with Example 1, Comparative Examples 1 to 6 investigated the component carbon fibers:

[0094] a) Comparative Example 1, which omitted carbon fibers, showed significant decreases in water permeability, antifreeze performance, and strength compared to Example 1, while its shock absorption performance was slightly improved. During the curing process of the permeable, shock-absorbing, antifreeze lightweight soil material, the supporting effect of carbon fibers prevents occlusion of micropores due to collapse or material shrinkage, ensuring a high effective porosity within the material. Furthermore, carbon fibers possess a certain degree of water conductivity, guiding water migration along the fiber distribution path, thereby forming a more efficient drainage network. The absence of carbon fibers, however, deprives the material of this reinforced network structure, significantly reducing water permeability. Furthermore, carbon fibers have strong electrical and thermal conductivity. Without them, the material cannot effectively and evenly transfer heat from the heating tubes, resulting in a decrease in antifreeze performance. However, due to the reduced overall rigidity of the material, it can absorb more vibration energy under dynamic loads, resulting in a slight improvement in shock absorption performance. Comparative Example 2, which added a small amount of carbon fibers, showed some improvement in its antifreeze performance and compressive strength. This is due to the small amount of carbon fibers acting as a "bridging" within the matrix, enhancing the internal microstructural stability of the material and improving the distribution and connectivity of the pores. In Comparative Example 3, adding excessive carbon fiber significantly improved the antifreeze performance, but the excess fiber tended to clumping inside the material, obstructing the water permeability. Furthermore, the fiber clumping effect caused stress concentration within the material, resulting in a decrease in compressive strength.

[0095] b) While maintaining the total number of components unchanged, Comparative Example 4, which omitted carbon fibers, showed slight improvements in water permeability, shock absorption, and strength compared to Comparative Example 1, but with a slight decrease in strength. This is because the addition of foam and water-absorbing resin increased porosity, thereby improving water permeability and the material's cushioning capacity. Simultaneously, the water-absorbing resin readily absorbed water to form a flexible gel, reducing the amount of free water in the pores and improving the material's antifreeze properties. However, the absence of carbon fibers deprived the material of the supportive reinforcement network, resulting in a weakening of its compressive strength. Comparative Example 5, which added a small amount of carbon fibers, improved its antifreeze properties and compressive strength, but slightly decreased its water permeability and shock absorption properties. The addition of a small amount of carbon fibers partially restored the reinforcing structure, improving the material's rigidity and stability. However, due to the high content of foam and water-absorbing resin, the small amount of carbon fibers failed to overlap within the material and form a sufficiently effective water-conducting structure, resulting in a slight decrease in water permeability. Comparative Example 6, which added an excessive amount of carbon fibers while significantly reducing the amount of foam and water-absorbing resin, improved its antifreeze properties and compressive strength, but decreased its water permeability and shock absorption properties. The high thermal conductivity of carbon fiber helps to quickly and evenly disperse temperature in low-temperature environments, reducing the risk of localized frost damage. However, due to the reduction in foam and water-absorbing resin content, the porosity of the material is greatly reduced, and its water permeability and shock absorption performance are reduced.

[0096] (3) Compared with Example 1, comparative examples 7 to 12 investigated the component foams:

[0097] 1) Comparative Example 7, which did not incorporate foam, exhibited high compressive strength but poor water permeability, frost resistance, and shock absorption. This is because the lack of foam resulted in a lower porosity within the material, reducing the channels for water drainage. Simultaneously, the material's rigidity increased, and it lacked a flexible buffer structure to absorb and disperse vibration energy, resulting in weak shock absorption. After a small amount of foam was added to Comparative Example 8, the porosity and flexibility of the material increased, significantly improving its water permeability, frost resistance, and shock absorption. After an excessive amount of foam was added to Comparative Example 9, the material's porosity was too high, its structure was loose, and its compressive strength decreased significantly, failing to meet basic load-bearing capacity requirements.

[0098] 2) While maintaining the total component count, Comparative Example 10, without the addition of foam, showed improved water permeability, antifreeze, and shock absorption compared to Comparative Example 7, but significantly reduced compressive strength. This is because, without the addition of foam, its content was distributed between the carbon fibers and the water-absorbing resin. The addition of the water-absorbing resin, through water absorption and expansion, optimized the pore structure, enhanced the material's flexibility, and further improved its antifreeze and shock absorption properties. The addition of carbon fibers further enhanced thermal conductivity, contributing to improved antifreeze performance. However, the lack of foam resulted in insufficient internal porosity, while the excess water-absorbing resin reduced rigidity, ultimately leading to a significant decrease in compressive strength. Comparative Example 11, with the addition of a small amount of foam, showed improved water permeability and shock absorption. The increased pore structure facilitated water drainage, while also enhancing flexibility and better absorbing and dissipating vibration energy. However, the low amount of foam and the high ratio of fiber to water-absorbing resin limited the uniformity of the material's internal pore structure, hindering the full fiber reinforcement effect. The flexible cushioning capacity of the water-absorbing resin was also limited, resulting in a relatively small improvement in shock absorption. In Comparative Example 12, the addition of excessive foam increased the material's porosity, making it more flexible under dynamic loads and thus improving its shock absorption performance. However, due to the insufficient fiber and water-absorbing resin content, a sufficient reinforcing network could not be formed, and its thermal conductivity and antifreeze properties were not demonstrated. Furthermore, while foam alone improved shock absorption, the lack of the reinforcing support of fiber and the regulating effect of water-absorbing resin resulted in a relatively small improvement in the material's mechanical properties.

[0099] (4) Compared with Example 1, Comparative Examples 13 to 18 investigated the component water-absorbing resins:

[0100] a) Comparative Example 13 exhibits reduced water permeability and antifreeze performance due to the lack of water-absorbing resin. Water-absorbing resin, by swelling upon absorbing water, fills the uneven micropores within the material and improves pore distribution and connectivity, thereby forming more effective water-permeable channels. Without the addition of water-absorbing resin, the material's pore structure is poorly regulated, hindering water penetration and drainage, significantly reducing water permeability. Furthermore, in low-temperature environments, the absence of water-absorbing resin deprives the material of its ability to mitigate ice expansion pressure and prevent water freezing, significantly degrading its antifreeze performance. Comparative Example 14, with the addition of a small amount of water-absorbing resin, significantly improves water permeability, antifreeze performance, and shock absorption. The water-absorbing resin, by forming a flexible gel structure, enhances the material's stability in low-temperature environments and improves its ability to absorb and buffer vibration energy. Comparative Example 15, with the addition of an excessive amount of water-absorbing resin, exhibits further improvements in water permeability and shock absorption, but significantly reduces antifreeze performance and compressive strength. Excessive water-absorbing resin swelling can cause the material to become too loose, weakening its overall rigidity and load-bearing capacity. In addition, too much water-absorbing resin can easily cause the material to absorb excessive water, resulting in uneven expansion force, increasing the risk of freeze-thaw damage at low temperatures, and ultimately leading to a decrease in antifreeze performance.

[0101] b) While maintaining the total number of components unchanged, Comparative Example 16, which omitted the water-absorbing resin, showed improvements in the material's water permeability, antifreeze performance, and shock absorption compared to Comparative Example 13. This is due to the increased porosity and flexibility of the foam, and the carbon fibers' thermal conductivity and reinforcing properties effectively compensating for the lack of antifreeze performance caused by the absence of the water-absorbing resin. However, the lack of gelation by the water-absorbing resin limited the improvement in antifreeze performance. Comparative Example 17, which added a small amount of water-absorbing resin, saw improvements in all material properties. However, due to the relatively high amounts of foam and fiber added, while the mechanical properties of the material were enhanced, the excessive fiber concentration led to overly concentrated heat conduction channels, limiting the improvement in antifreeze performance. Comparative Example 18, which added an excessive amount of water-absorbing resin, further improved water permeability and shock absorption, but the material was too soft, resulting in a loose and brittle structure and a significant decrease in compressive strength, making it unable to meet engineering load-bearing requirements. Furthermore, due to the low fiber content, an effective reinforcement network could not be formed, resulting in a lack of sufficient thermal conductivity to evenly distribute heat in low-temperature environments, limiting further improvements in antifreeze performance.

[0102] (5) Compared with Example 1, Comparative Example 19 does not add carbon fiber and water-absorbing resin, and the other components and contents are consistent with Example 1; from the data comparison, it can be seen that the water permeability, antifreeze performance and shock absorption performance of the material are significantly reduced. This is mainly because the carbon fiber not only plays a reinforcing role in the material, but also improves the shock absorption and antifreeze performance by improving the pore distribution and forming a heat conduction network; the water-absorbing resin increases the internal porosity of the material by absorbing water and expanding, and at the same time inhibits water freezing in a low-temperature environment, thereby enhancing the antifreeze performance. In addition, when the water-absorbing resin and foam work together, they can further optimize the pore structure and balance the water permeability and shock absorption, while the carbon fiber can limit the deformation of the material and avoid the decline in mechanical properties due to excessive foam. Therefore, the synergistic effect of carbon fiber, water-absorbing resin and foam is crucial in improving the water permeability, antifreeze performance and shock absorption performance of the material. The lack of any one of these components will destroy this balance, resulting in a decline in material performance.

[0103] (6) Compared with Example 1, Comparative Example 20 does not add water-absorbing resin and foam, and the other components and contents are consistent with Example 1. From the data comparison, it can be seen that the lack of water-absorbing resin and foam leads to the reduction of various properties. Due to the lack of water-absorbing resin, the material loses the ability to absorb water and expand to form a gel in a low-temperature environment, and cannot effectively prevent water from freezing, and the antifreeze performance is significantly weakened. At the same time, the lack of water-absorbing resin also reduces the optimization effect of the pore structure, affecting the water permeability and shock absorption. The lack of foam further leads to a decrease in porosity, difficulty in water discharge, increased overall rigidity of the material, and decreased shock absorption. In addition, due to the synergistic effect of water-absorbing resin and foam, the structural continuity and bearing capacity of the material can be maintained while enhancing the water permeability and shock absorption. However, due to the lack of these two components, Comparative Example 20 shows problems such as insufficient water permeability, weak antifreeze performance, poor shock absorption effect, and limited strength improvement. This shows that the combination of water-absorbing resin and foam can improve the performance of the material while ensuring its applicability in actual engineering applications.

[0104] (7) Compared with Example 1, Comparative Example 21 does not add foam and carbon fiber, and the other components and contents are consistent with Example 1. From the data comparison, it can be seen that: without the addition of foam, the internal porosity of the material is significantly reduced, the water permeability is insufficient, and the flexible cushioning effect provided by the foam is lost, and the shock absorption performance deteriorates; without the addition of carbon fiber, the material loses the ability to enhance and disperse vibration energy, and the thermal conductivity is weakened, affecting the antifreeze performance. In addition, the synergistic effect of foam and carbon fiber can optimize the pore structure and improve the comprehensive performance of the material in Example 1, while Comparative Example 21, due to the lack of these two key components, shows problems of excessive rigidity and insufficient pore structure, resulting in a comprehensive decline in water permeability, antifreeze and shock absorption performance.

[0105] As described above, in Example 1, the synergistic effect between the foam, water-absorbing resin, and carbon fibers significantly enhances the various properties of the permeable, shock-absorbing, and frost-resistant lightweight soil. First, the addition of foam increases the material's porosity, effectively improving its water permeability. Simultaneously, the water-absorbing resin, through its expansion, improves the material's pore structure, enhancing its water permeability and improving its shock-absorbing properties. This combination ensures that the lightweight soil material possesses both high water permeability and excellent shock-absorbing properties.

[0106] Secondly, the synergistic effect of foam and carbon fiber enhances shock absorption performance. The foam provides greater deformation space, allowing the material to better absorb energy when subjected to vibration, while the addition of carbon fiber enhances the material's impact and crack resistance, making it more resilient under dynamic loads. This combination ensures the lightweight soil material's optimized shock absorption performance.

[0107] Finally, the synergistic effect of the water-absorbing resin and carbon fibers enhances frost resistance. The water-absorbing resin expands as it absorbs water, reducing damage to the material's structure when water freezes. The carbon fibers, on the other hand, enhance thermal conductivity, helping the material heat more evenly in low-temperature environments and preventing water from freezing in its pores. This combination of properties makes the lightweight soil material even more frost-resistant at low temperatures.

[0108] In summary, the synergistic effect between foam, water-absorbing resin and carbon fiber plays a positive role in enhancing the lightweight soil material, which not only optimizes its permeability and shock absorption, but also enhances its anti-freezing performance, making the material have stronger comprehensive performance and adapting to diverse engineering needs.

[0109] Therefore, through the permeable, shock-absorbing, and frost-resistant lightweight soil filling material and optimized drainage system design in this embodiment, the tunnel structure's drainage capacity, seismic resistance, and frost resistance are significantly improved. This structural type forms an efficient drainage channel at the tunnel bottom, allowing for the timely removal of accumulated water and preventing the accumulation of water pressure. Furthermore, the material absorbs and disperses the vibration energy generated by dynamic loads, enhancing the tunnel structure's seismic resistance and safety.

[0110] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A permeable shock-absorbing and anti-freezing lightweight soil material, characterized in that: The raw material composition includes, by weight: 31.52 parts of cement, 7.88 parts of fine sand, 2.62 parts of foam, 0.16 parts of carbon fiber, 0.59 parts of water-absorbing resin, 0.03 parts of thickener, and 11.82 parts of water; The carbon fiber has electrical and thermal conductivity; The density of the foam is 42.5~65 kg / m 3 ; The preparation method of the water-permeable shock-absorbing and anti-freezing lightweight soil material is specifically as follows: first, water-absorbing resin is allowed to absorb water to a gel state to obtain water-absorbing resin gel, and foam is whipped; then, water, cement, fine sand and carbon fiber are mixed and stirred until the slurry is uniform to obtain cement slurry; the water-absorbing resin gel is added to the cement slurry to obtain a uniform slurry; finally, the whipped foam and thickener are added to the slurry and stirred to obtain a mixture, which is the water-permeable shock-absorbing and anti-freezing lightweight soil material.

2. The permeable shock-absorbing and antifreeze lightweight soil material according to claim 1, characterized in that: The cement is selected from one or more of ordinary Portland cement, white cement, aluminate cement, blast furnace slag cement, a mixture of Portland cement and mineral powder, and quick-setting cement; The fine sand is selected from one of natural fine sand, artificial fine sand and river sand, and has a particle size of 0.075-1 mm; The foam is produced by physical foaming in a foaming machine through an air compressor, and the foam density is 42.5-65 kg / m 3 ; The foaming agent is selected from one or more of animal protein foaming agents, plant protein foaming agents and composite surfactants; The water-absorbing resin is selected from one or more of polyacrylic acid water-absorbing resin, polyvinyl alcohol water-absorbing resin, starch graft copolymer water-absorbing resin, cellulose-based water-absorbing resin, natural polymer water-absorbing resin and organic-inorganic composite water-absorbing resin; The thickener is selected from one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose and methyl cellulose.

3. A method for preparing the permeable shock-absorbing and antifreeze lightweight soil material according to any one of claims 1 to 2, characterized in that: Specifically, the water-absorbing resin is firstly allowed to absorb water to a gel state to obtain a water-absorbing resin gel, and foam is then whipped. Then, water, cement, fine sand and carbon fiber are mixed and stirred until a slurry is uniform to obtain a cement slurry. The water-absorbing resin gel is added to the cement slurry to obtain a uniform slurry. Finally, the whipped foam and a thickener are added to the slurry and stirred to obtain a mixture, which is a water-permeable shock-absorbing and anti-freezing lightweight soil material. The cement slurry is prepared by stirring at 300-400 r / min for 60-120 s. The uniform slurry is prepared by stirring at 100-200 r / min for 30-90 s; The mixture is prepared by stirring at 100-200 r / min for 30-90 s.

4. Use of the permeable, shock-absorbing and anti-freezing lightweight soil material according to any one of claims 1 to 2 in the field of tunnels and underground engineering.

5. A high-efficiency drainage structure for a tunnel, characterized in that: It comprises the permeable shock-absorbing and antifreeze lightweight soil material according to any one of claims 1 to 2, and the permeable shock-absorbing and antifreeze lightweight soil material is filled in the filling ditch of the tunnel with a high-efficiency drainage structure.

6. The high-efficiency drainage structure for tunnels according to claim 5, characterized in that: The high-efficiency drainage structure for the tunnel also includes a longitudinal drainage pipe, a water collection ditch and a filter screen; Among them, the longitudinal drainage pipe is arranged on the surrounding rock of the arch wall on both sides of the tunnel; the water collection ditch is arranged between the tunnel invert arch and the track; the filling ditch is arranged between the water collection ditch and the tunnel arch foot, and is symmetrically arranged on both sides of the water collection ditch; the filter is arranged at the connection between the roads on both sides of the track, the filling ditch and the surrounding rock of the arch wall on both sides.

7. The high-efficiency drainage structure for tunnels according to claim 5, characterized in that: The tunnel uses a high-efficiency drainage structure type arranged in the tunnel within a range of ≥50 m from the entrance.

8. The high-efficiency drainage structure for tunnels according to claim 7, characterized in that: In the filling trench within the tunnel entrance, heating rods are evenly laid every 0.5 to 1 m and cast in the foam lightweight soil; the heating rods are arranged in a regular array in the plane of the filling trench, specifically in two rows with longitudinal spacing; the heating rods are evenly spaced in the row and column directions and meet the design requirement of 0.5 to 1 meter spacing; when the temperature is below 0°C, the power supply equipment is turned on to heat the permeable, shock-absorbing and anti-freezing lightweight soil material.

9. The high-efficiency drainage structure for a tunnel according to claim 6, characterized in that: The outside of the tunnel surrounding rock where the longitudinal drainage pipe is located also includes a cast-in-place base and anti-backward push stones; The length of the filter is 0.8~1.2 m. After the surface water on the road is initially filtered through the filter, it seeps into the filling ditch and is discharged into the collection ditch. The filter is made of high-strength material that is corrosion-resistant and wear-resistant, and the filter aperture is set at 0.5~2 mm.

10. The high-efficiency drainage structure for tunnels according to claim 6, characterized in that: Drainage holes are set every 1.5~2 m on both sides of the ditch along the track direction. The diameter of the drainage holes is 8~10 cm and they are arranged at intervals up and down along the side walls of the ditch to enhance drainage efficiency.

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