Underground roadway waterproof supporting structure and waterproof supporting method thereof

Abstract

An underground roadway waterproof supporting construction method comprises the following steps that anchor rods are constructed on the surface of a to-be-supported roadway after drainage, and a first reinforcing mesh and a second reinforcing mesh are installed on the constructed anchor rods; reinforcing ribs are arranged on the first reinforcing mesh at intervals; the second reinforcing mesh comprises a layer of reinforcing mesh sheet and a layer of mining flame-retardant plastic mesh, and the mining flame-retardant plastic mesh is located between the first reinforcing mesh and the reinforcing mesh sheet; a first material is sprayed on the surface of the second reinforcing mesh to construct a supporting layer, grouting holes are reserved in the supporting layer, and the supporting layer is used for providing high-strength waterproof anti-seepage support for the roadway; after the supporting layer is finally set, grouting of a second material is conducted between the supporting layer and the surface of the roadway to be supported through the grouting holes so as to construct a buffer layer, and the buffer layer is used for providing buffer for deformation and movement of the roadway; a gap between every two adjacent supporting layers serves as an expansion joint, and a back-attached type waterproof structure and / or a middle-buried type water bag waterproof structure are / is constructed at the expansion joints.

Description

Technical Field

[0001] The present invention relates to the technical field of support, and in particular to a waterproof support structure for underground roadways and a waterproof support construction method therefor. Background Art

[0002] An underground roadway is a passageway excavated for mining hoisting, transportation, ventilation, drainage, power supply, etc. during underground mining. The cross-sectional shape of the roadway is mostly arched, trapezoidal or rectangular, and circular, elliptical or horseshoe-shaped for soft surrounding rocks.

[0003] During the support construction process of current underground roadways, especially in projects such as mines, tunnels, and subways, the water damage problem has always been a major factor affecting the safety, stability and construction progress of the project. This is because as the mining depth of the underground roadway increases continuously, the geological conditions are complex and changeable, and various water sources such as groundwater, fissure water, and precipitation may penetrate into the roadway, affecting the stability of the support structure and bringing construction difficulties. The water damage is mainly reflected in the following aspects: seepage and water accumulation. The underground roadway is easily penetrated by groundwater and surface water, resulting in water accumulation in the roadway, affecting construction safety and the working environment of personnel. Water pressure influence. Especially in high water level areas, the osmotic pressure of water may exert great pressure on the roadway support structure, even causing support failure. Geological deformation caused by water damage. The penetration of water may cause softening or swelling of the surrounding soil and rock, further causing roadway collapse or stratum instability.

[0004] During the construction process of underground roadways, waterproof measures often rely on simple physical isolation means, such as setting up drainage systems and using waterproof coatings during construction. However, these measures usually have limited effects and are difficult to solve the influence of deep groundwater penetration and high water pressure on the roadway structure, which urgently needs to be solved. Summary of the Invention

[0005] In order to solve the above problems, an underground roadway waterproof support structure and a waterproof support construction method therefor are provided in the embodiments of the present application, which can achieve rapid support while having better anti-seepage and waterproof performance.

[0006] To this end, the following technical solutions are adopted in the embodiments of the present application:

[0007] In a first aspect, an underground roadway waterproof support construction method is provided in an embodiment of the present application, including the following steps: constructing bolts on the surface of the roadway to be supported after draining water and installing a first steel mesh and a second steel mesh on the constructed bolts; wherein, reinforcing ribs are arranged at intervals on the first steel mesh; the mesh size of the second steel mesh is smaller than that of the first steel mesh, and the second steel mesh includes a layer of steel mesh and a layer of mine-use anti-flammable and anti-static plastic mesh, and the mine-use anti-flammable and anti-static plastic mesh is located between the first steel mesh and the steel mesh.

[0008] Spray a first material on the surface of the second steel mesh to construct a support layer, and reserve grouting holes on the support layer. The support layer is used to provide high-strength and stable support for the roadway;

[0009] After the support layer has finally set, grout a second material between the support layer and the surface of the roadway to be supported through the grouting holes to construct a buffer layer. The buffer layer is used to provide buffering for the deformation and movement of the roadway;

[0010] The gap between two adjacent support layers serves as an expansion joint, and a back-bonded waterproof structure and / or an embedded water bag waterproof structure is constructed at the expansion joint;

[0011] Among them, the first material includes the following components in parts by weight: 20-60 parts of cement, 10-15 parts of vitrified microspheres, 1-10 parts of waterproof agent, 1-5 parts of composite expansion material, 20-40 parts of admixture, 0.5-1.5 parts of water reducing agent, 1-5 parts of early strength agent, 2-4 parts of thixotropic agent, 80-120 parts of high-strength aggregate, 3-6 parts of accelerating agent, 5-15 parts of modified polyvinyl alcohol fiber, and 10-30 parts of water;

[0012] The preparation method of the modified polyvinyl alcohol fiber includes the following steps:

[0013] Soak the polyvinyl alcohol fiber in a sodium hydroxide solution, stir for 1-3 h, wash with water, then immerse it in absolute ethanol, soak for 1-2 h, and dry to obtain a modified fiber precursor;

[0014] Ultrasonically disperse the carbon nanotubes in ethanol, then add the modified fiber precursor, stir for 1-2 h, and dry to obtain a modified fiber intermediate;

[0015] Dissolve graphene oxide in acetic acid, then add the modified fiber intermediate, stir for 2-5 h, and then dry to obtain the modified polyvinyl alcohol fiber;

[0016] The weight ratio of the polyvinyl alcohol fiber, carbon nanotubes, and graphene oxide is 1:(0.5-0.8):(0.4-0.6).

[0017] In this embodiment, bolt construction is carried out on the roadway surface. The bolts firmly fix the roadway structure, providing a stable foundation for subsequent support. A first steel mesh and a second steel mesh are installed on the bolts. The first steel mesh plays a role in enhancing the overall structure, while the second steel mesh increases the anti-permeability performance through a fine grid design and the addition of a composite flame-retardant plastic mesh. The grid size of the second steel mesh is smaller than that of the first steel mesh, which can effectively reduce the possibility of water penetration and increase the waterproofness of the roadway structure. A first material is sprayed on the second steel mesh to form a solid support layer, which provides high-strength stable support. After the support layer is cured, a second material is injected to form a buffer layer. The function of the buffer layer is to provide appropriate space for the deformation of the roadway and relieve pressure, preventing structural instability caused by water damage. Expansion joints are formed between the support layers, and waterproof structures such as back-mounted waterproof structures and / or embedded water bag waterproof structures are installed at the expansion joints to further enhance the protection ability against water damage. The first material contains various components such as cement, vitrified microspheres, waterproof agents, and composite expansion materials, and has excellent strength, anti-permeability, and rapid setting characteristics. The first material in this technical solution also includes modified polyvinyl alcohol fibers, which have been specially treated, including soaking, drying, and adding reinforcing materials such as carbon nanotubes and graphene oxide, and can significantly improve the anti-permeability performance and strength of the material. Through the double-layer steel mesh and the special waterproof support layer, the penetration of water sources can be effectively isolated, preventing water damage to the roadway structure. The combination of the support layer and the buffer layer can effectively relieve the deformation of the roadway caused by groundwater pressure and soil deformation, thereby improving the overall stability of the roadway. The rapid setting and reinforcing materials can significantly shorten the construction time, improve the construction efficiency, and ensure smooth construction in complex environments. Through the application of modified polyvinyl alcohol fibers and nanotechnology, the water resistance, anti-permeability, and corrosion resistance of the material can be significantly improved, ensuring long-term stable use. This underground roadway waterproof support method provides a multi-level waterproof solution. By combining means such as bolt support, steel mesh structure, special materials, and buffer layer, the problems brought by water damage in underground roadway construction can be effectively solved. Through the application of modified polyvinyl alcohol fibers, the waterproof performance and durability of the material are improved, and at the same time, the safety and construction efficiency of the roadway structure are improved through innovative design.

[0018] Specifically, during the preparation process of the modified polyvinyl alcohol fibers, the PVA fibers are surface-treated by immersing them in a sodium hydroxide solution, enabling them to form a better bond with the subsequent carbon nanotubes and graphene oxide. The sodium hydroxide solution can disrupt the surface structure of the PVA fibers, increasing the surface roughness and thus enhancing the adhesion of the subsequent modifiers (such as carbon nanotubes and graphene oxide). Water washing is to remove the residual sodium hydroxide and avoid affecting the subsequent steps. The immersion step in absolute ethanol helps remove moisture and maintain the surface state of the fibers suitable for further treatment with carbon nanotubes. The dispersibility of carbon nanotubes is a key factor affecting their modification effect. Due to the poor hydrophilicity and strong agglomeration of carbon nanotubes, ultrasonic dispersion can effectively break the aggregation of carbon nanotubes, dispersing them into monomers or small clusters, thereby improving their compatibility with polyvinyl alcohol fibers. Dispersing carbon nanotubes in ethanol is a reasonable choice. Ethanol as a solvent can not only help disperse carbon nanotubes but also dissolve impurities that are not easily soluble in water. Then it is mixed with the modified fiber precursor, and stirring is carried out to evenly attach the carbon nanotubes to the fiber surface. Graphene oxide is an excellent nanomaterial with strong hydrophilicity and good dispersibility, capable of enhancing the mechanical properties, electrical conductivity, etc. of the material. Here, the purpose of using acetic acid to dissolve graphene oxide is to improve the dispersibility of graphene oxide through an acidic solvent and reduce the aggregation of graphene sheets. After adding the modified fiber intermediate, stirring is carried out to evenly coat the graphene oxide on the fiber surface and form a composite structure with the carbon nanotubes, thereby enhancing the modification effect. The mass ratio of polyvinyl alcohol fibers, carbon nanotubes, and graphene oxide is 1:0.5 - 0.8:0.4 - 0.6. The polyvinyl alcohol fibers are the main component, and the carbon nanotubes and graphene oxide are used as additives. The ratios of carbon nanotubes and graphene oxide are respectively between 0.5 - 0.8 and 0.4 - 0.6. Such a ratio can ensure the optimization of the properties of the composite material. Adjusting the ratios of carbon nanotubes and graphene oxide can affect properties such as the mechanical properties of the final composite material. A reasonable ratio design helps improve various properties of the composite material, such as its anti-seepage, anti-cracking, and mechanical properties, while ensuring the properties of the fiber matrix.

[0019] In addition, due to the different physical shapes such as the appearance morphology, internal structure, surface properties, and particle gradation of the modified polyvinyl alcohol fiber, vitrified microspheres, waterproofing agent, and composite expansion material, a morphological effect can be generated. The sizes of different morphologies intersect with each other. The modified polyvinyl alcohol fiber has a special-shaped structure, which can adhere to the materials with each other and play the role of aggregate. Moreover, the size of the modified polyvinyl alcohol fiber is small, and it is easy to form a dense random network, playing the role of a reinforcing bar. The spherical solid vitrified microspheres can improve the dispersion performance of the modified polyvinyl alcohol fiber and make the fiber adhere tightly to the cement. The above components are evenly distributed in the concrete to form an interactive network, effectively reducing the generation of concrete pores, improving the impermeability, and preventing the generation and development of cracks. At the same time, the addition of the above components can play a micro-aggregate effect. The modified polyvinyl alcohol fiber, vitrified microspheres, waterproofing agent, and composite expansion material are evenly distributed in the cement paste, reducing the pores of the concrete, not only improving the toughness of the concrete but also inhibiting the generation of microcracks. These effects greatly improve the mechanical and impermeability properties of the concrete.

[0020] It can be understood that the second material for constructing the buffer layer can be a material with good elasticity and compressive strength, which can effectively absorb and disperse stress. For example, lightweight foam concrete prepared with lightweight aggregates (such as expanded perlite, ceramsite, or rubber particles) can reduce the weight of the overall structure while providing a good buffering effect. Mineral admixtures play a role in filling and refining particles in the concrete, increasing the density and strength of the material. The thixotropic agent can increase the viscosity and plasticity of the concrete, enabling the second concrete material to achieve good slurry adhesion with the substrate and improving the spraying construction performance of the second concrete material. The addition of the accelerating agent and early-strength agent enables this construction method to achieve rapid connection of construction processes, improve construction efficiency, shorten the construction period, and balance construction efficiency and support stability.

[0021] As an implementable embodiment, the weight ratio of the polyvinyl alcohol fiber, carbon nanotube, and graphene oxide is 1:0.6:0.5. After verification by the inventor, at this ratio, the modified polyvinyl alcohol has better flexibility, thereby improving its compatibility with the concrete matrix. It can keep the mixed concrete evenly in its original state and stable, and reduce the shrinkage and expansion of the system. When sprayed on the side wall or top of the underground roadway, it has good stability and is not prone to delamination. When cracks are generated in the concrete due to hydration heat, it can bridge microcracks, control the crack width, improve the compressive strength of the matrix, and also inhibit the development of cracks, improve its impermeability and waterproof performance, and improve the load-bearing capacity and compressive strength of the concrete.

[0022] As an implementable embodiment, the weight ratio of the modified polyvinyl alcohol fiber, vitrified microspheres, waterproofing agent, and composite expansion material in the first material is (5-10):(12-13):(5-7):(3-4).

[0023] In this embodiment, the composite expansion material fully improves the density of the concrete and effectively prevents the occurrence of shrinkage cracks in the concrete. Specifically, the addition of the modified polyvinyl alcohol fiber can reduce the number of defects such as cracks and voids in the concrete, thereby improving the impermeability and compressive strength of the concrete and enhancing the safety and structural stability of the support layer; the addition of vitrified microspheres can change the pore structure of the concrete and improve its physical properties; and the waterproofing agent causes a hydration reaction inside the concrete to improve the impermeability of the concrete. Through reasonable proportioning, the concrete with the optimal proportion is obtained, and its mechanical, waterproof and impermeability properties are comprehensively improved.

[0024] As an implementable embodiment, the weight ratio of the modified polyvinyl alcohol fiber, vitrified microspheres, waterproofing agent, and composite expansion material in the first material is 8:12:7:4.

[0025] In this embodiment, the modified polyvinyl alcohol fiber, vitrified microspheres, waterproofing agent, and composite expansion material with a ratio of 8:12:7:4 give full play to the advantages of each component, enhancing the waterproofness, impermeability, crack resistance, and structural stability of the waterproof support structure of the underground roadway.

[0026] Preferably, the particle size of the vitrified microspheres is 5-20 μm, and the vitrified microspheres are solid vitrified microspheres. The vitreous content of the fine vitrified microspheres is more than 90%, which can effectively fill between the cement particles and has a certain water-reducing and plasticizing effect. The solid vitrified microspheres have a smooth surface and a high porosity, which can effectively reduce the ability of water penetration. At the same time, they can form a dispersed pore structure in the cement-based material, enhancing the compressive performance of the composite material. The addition of fillers such as aramid nanofibers, flat glass fibers, graphene, and solid glass microspheres can produce a synergistic strengthening effect on the concrete.

[0027] As an implementable embodiment, the waterproofing agent includes sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid, and sodium dodecyl sulfate with a weight ratio of (30-60):(5-15):(1-5):(1-3).

[0028] In this embodiment, sodium metasilicate tetrahydrate can react with the calcium components in cement to form calcium silicate hydrate (C-S-H gel). These gels can fill the pores inside the cement, improve the compactness of the concrete, reduce the penetration path of water, and play a role in water isolation and anti-seepage. Anhydrous sodium carbonate mainly acts as an activator, which can promote the hydration reaction of sodium metasilicate tetrahydrate and enhance its reaction ability with other components in the cement. It can accelerate the crystallization process, help form dense crystals, and improve the waterproof effect. Ethylenediaminetetraacetic acid is a chelating agent. Its main role in cement-based permeable crystalline waterproof materials is to stabilize the reaction system, prevent the interference of metal ions (such as calcium, magnesium, etc.) or other adverse ions, thereby improving the stability and durability of the concrete. By binding with metal ions, ethylenediaminetetraacetic acid can effectively reduce the pores formed due to the precipitation of metal ions in the cement matrix, improve the compactness of the concrete, and thus enhance the impermeability. It can also help regulate the pH value in the cement paste, promote the reaction of calcium and silicon in the material, and improve the crystallization effect. Sodium dodecyl sulfate mainly acts as a dispersant in cement-based permeable crystalline waterproof materials. It can help improve the dispersibility of each component, enhance the fluidity and uniformity of the material. It can also help improve the adhesion between the cement and the waterproof material and enhance the construction performance of the material. In the waterproof material, sodium dodecyl sulfate can promote the interaction between each component, making a denser waterproof crystal network formed in the cement matrix.

[0029] As an achievable embodiment, the waterproof agent comprises sodium metasilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid, and sodium dodecyl sulfate in a weight ratio of (40 - 50):(10 - 15):(3 - 5):(1 - 3).

[0030] As an achievable embodiment, the waterproof agent comprises sodium metasilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid, and sodium dodecyl sulfate in a weight ratio of 45:10:4:2.

[0031] In this embodiment, the formula of the waterproof agent exerts the unique functions of each substance through reasonable component ratios, synergistically improving the performance of the waterproof material. Sodium metasilicate tetrahydrate improves the waterproofness and impermeability, anhydrous sodium carbonate adjusts the alkalinity, ethylenediaminetetraacetic acid enhances the stability and durability of the concrete, while sodium dodecyl sulfate optimizes the dispersibility and emulsification effect during construction. Overall, the waterproof agent formula has high waterproof efficiency, good construction performance, and cost-effectiveness, and is an excellent material suitable for underground buildings and waterproof projects.

[0032] As an implementable embodiment, the composite expansion material is formed by wrapping a core material with a coating material, and the coating material accounts for 1-4% of the weight of the core material; the core material comprises raw materials in the following parts by weight: 100 parts of fiber expansion agent, 10-15 parts of bentonite, 1-5 parts of potassium alum, and 4-8 parts of zeolite powder; the coating material comprises raw materials in the following parts by weight: 10-20 parts of sodium methacrylate, 2-5 parts of sodium alginate, and 5-10 parts of polyvinyl alcohol.

[0033] In this embodiment, the composite expansion material takes the core material as the core layer and the coating material as the shell layer to form the composite expansion material, which has the effect of slow-release expansion; as the service time of the concrete extends, the coating material of the composite expansion material gradually decomposes and the core material is gradually exposed. At this time, the fiber expansion agent and bentonite in the core material can play their roles of water absorption and expansion, crack resistance and impermeability, thereby inhibiting the development of cracks; potassium alum has gelling properties and can react with the moisture in the concrete to generate a colloidal substance, filling the concrete cracks and enhancing the continuity and durability of the material; zeolite has good adsorption properties and ion exchange effects, which can enhance the weather resistance and water resistance of the composite material and improve its long-term performance. For example, the gelling substance formed by zeolite powder in combination with the fiber expansion agent, bentonite and potassium alum is filled into the gaps of the concrete, thereby improving the compactness of the concrete to slow down the decline of the compressive strength of the concrete, thereby improving the durability of the concrete. Sodium methacrylate is a water-soluble polymer that can form a stable protective film on the material surface, enhancing the corrosion resistance and water resistance of the material, and at the same time promoting the uniformity of the expansion reaction. Sodium alginate has good bonding properties, which can enhance the adhesion of the coating material and improve the overall stability and durability of the composite expansion material. It can also improve the hydrolysis resistance of the composite material. Polyvinyl alcohol is a water-soluble synthetic polymer material that can improve the mechanical strength and tensile property of the coating layer and enhance the integrity and stability of the film formed during the expansion of the material.

[0034] Optionally, the fiber expansion agent is an MPC polymer fiber expansion agent, which is compounded from a redispersible polymer, a ternary expansion component, and high-strength polypropylene fibers, and has the functions of early strength, expansion, shrinkage compensation, and improving the crack resistance and impermeability of concrete. Since the monofilament fibers in the polymer fiber expansion agent are evenly distributed inside the concrete in a large quantity per unit volume, the microcracks will inevitably encounter the obstruction of the fibers during the development process, consuming most of the energy. The four components of CaO-MgO-Al2O3-SO3 form three different expansion sources, and their simultaneous hydration rates are different. During the formation of concrete, different micro-expansion forces in the early, middle, and late stages are established to resist the shrinkage forces at different times during the formation of concrete. Therefore, the cracks are difficult to develop further, thus achieving the effect of crack resistance. In particular, the addition of fibers is like adding a huge number of fine steel bars to the concrete, forming a secondary reinforcement effect in the concrete, enabling the expansion components to play more fully under restricted conditions. The superimposed effect makes the concrete more dense and stable; greatly weakens the cracking process and improves the fracture toughness of the concrete. The fibers are randomly distributed in the concrete to form a three-dimensional network structure, and the expansion components compensate for shrinkage. The redispersible polymer plays a role in bonding and hydrophobia. The superimposed effect generated by the three mutually complementary and complementary effects can greatly reduce cracks, control the appearance of harmful cracks, and give new vitality to the concrete.

[0035] As an implementable embodiment, the composite expansion material is prepared by the following method: by weight, take 100 parts of fiber expansion agent, 10 - 15 parts of bentonite, 1 - 5 parts of potassium alum, and 4 - 8 parts of zeolite powder, grind and dry to obtain the core material;

[0036] Take 40 - 50 parts of sodium methacrylate and 2 - 5 parts of sodium alginate, add them to 200 - 300 parts of water, stir evenly, heat to 60 - 80 °C, keep stirring for 30 - 50 min, add 5 - 10 parts of polyvinyl alcohol, then raise the temperature to 85 - 90 °C, and stir at a speed of 3000 - 4000 r / min for 20 - 30 min to obtain the coating solution;

[0037] Put the core material into a coating granulator, spray the coating solution onto the core material. The rotation speed of the coating granulator is 15 - 20 r / min, the temperature is 60 - 70 °C, and the liquid spraying speed is 15 - 18 g / min. After coating, dry the obtained coated particles through hot air until completely cured, and then cool them at room temperature to obtain the composite expansion material.

[0038] In this embodiment, by reasonably selecting the core material and the coating material, an efficient composite expansion material can be designed. While ensuring its slow-release expansion effect, through reasonable material proportioning and preparation process, it can not only effectively improve the waterproof and impermeable properties of concrete, but also enhance its mechanical properties and durability, meeting the strict requirements for the performance of concrete in engineering.

[0039] In a second aspect, an underground roadway waterproof support structure is prepared by the underground roadway waterproof support method of the first aspect above, and includes a buffer layer and a support layer; wherein, the support layer is constructed of a first material, and the first material includes the following components in parts by weight: 20-60 parts of cement, 10-15 parts of vitrified microspheres, 1-10 parts of waterproof agent, 1-5 parts of composite expansion material, 20-40 parts of admixture, 0.5-1.5 parts of water reducing agent, 1-5 parts of early strength agent, 2-4 parts of thixotropic agent, 80-120 parts of high-strength aggregate, 3-6 parts of accelerating agent, 5-15 parts of modified polyvinyl alcohol fiber, and 10-30 parts of water; the preparation method of the modified polyvinyl alcohol fiber includes the following steps: soaking the polyvinyl alcohol fiber in a sodium hydroxide solution, stirring for 1-3 h, washing with water, then immersing it in absolute ethanol, soaking for 1-2 h, and drying to obtain a modified fiber precursor; ultrasonically dispersing carbon nanotubes in ethanol, then adding the modified fiber precursor, stirring for 1-2 h, and drying to obtain a modified fiber intermediate; dissolving graphene oxide in acetic acid, then adding the modified fiber intermediate, stirring for 2-5 h, and then drying to obtain the modified polyvinyl alcohol fiber; the weight ratio of the polyvinyl alcohol fiber, carbon nanotubes, and graphene oxide is 1:(0.5-0.8):(0.4-0.6).

[0040] As an implementable embodiment, the early strength agent includes acyloxy silane, sodium thiosulfate, and triethanolamine with a weight ratio of 3:4:2.

[0041] In this embodiment, acyloxysilane is used as a chemical modifier. Acyloxysilane can improve the adhesion between the cement paste and the aggregate, enhance the overall strength of the concrete, and form a silicon oxide structure during the cement hydration process, further enhancing the durability of the concrete. Sodium thiosulfate is usually used as an accelerator, which can promote the hydration reaction of cement, thereby increasing the early strength. It can react with calcium ions in the cement, increase the activity of cement particles, and thus accelerate the hardening process. As an organic base, triethanolamine can increase the rate of the cement hydration reaction, improve the fluidity and workability of the concrete. It can effectively reduce the initial viscosity of the concrete, making the improvement of the early strength more obvious. The early strength agent significantly increases the early strength of the concrete and improves its physical and mechanical properties through the synergistic effect of its components. This enables more efficient meeting of construction requirements in projects that require rapid forming. After verification, the early strength agent in the above proportion can promote the hydration reaction of cement, resulting in more hydration products (such as C-S-H gel) being generated early, thereby increasing the early strength. At the same time, it makes the microstructure of the concrete denser, reduces the porosity, and enhances the compressive strength.

[0042] As an implementable embodiment, the cement is P.O52.5 cement.

[0043] As an implementable embodiment, the admixture is mesoporous molecular sieve.

[0044] As an implementable embodiment, the water reducer is polycarboxylate water reducer.

[0045] As an implementable embodiment, the thixotropic agent includes nano-alumina fiber, nano-silica fiber and nano-carbon fiber with a weight ratio of 0.5:3:4.

[0046] As an implementable embodiment, the high-strength aggregate is quartz sand, and the particle size of the quartz sand is 1.0 - 1.8 mm.

[0047] In the third aspect, the embodiment of the present application also provides an application of an underground roadway waterproof support structure, and the support construction method can be applied to any one of the support of coal mine roadways, the support of deep foundation engineering foundation pits, the support of subway roadway walls, the foundation support of large or high-rise buildings, the support of highway roadways and the support of hydraulic tunnels. Description of the Drawings

[0048] Figure 1 Shows the schematic diagram of the waterproof support structure constructed by the first underground roadway waterproof support construction method provided in Embodiment 1 of the present application;

[0049] Figure 2 Shows the schematic diagram of the waterproof support structure constructed by the second underground roadway waterproof support construction method provided in Embodiment 2 of the present application. Specific Embodiments

[0050] The technical solutions in the embodiments of the present application will be described below.

[0051] It should be specifically noted that: unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the raw materials, instruments, and equipment used in the following embodiments can all be obtained through market purchases or can be obtained by existing methods; the dosages of the experimental reagents are all the dosages of the reagents in conventional experimental operations unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0052] The cement in the first material in the embodiments of the present application is P.O52.5 cement; the admixture is mesoporous molecular sieve; the thixotropic agent includes nano-alumina fiber, nano-silica fiber, and nano-carbon fiber with a weight ratio of 0.5:3:4; the water reducer is a polycarboxylic high-performance water reducer with a water reduction rate of 26.8%; the high-strength aggregate is quartz sand with a particle size of 1.0 - 1.8 mm; the rubber particles are made from waste natural rubber with a crushing particle size of 35 - 40 mesh; the foaming agent is sodium dodecyl sulfate, and the foaming agent is used to prepare nano-foam through a nano-foam generator. Polyvinyl alcohol fiber, with a length of 12 mm, an elastic modulus of 41 GPa, a tensile strength of 1550 MPa, an elongation at break of 6.5%, and a density of about 1.3 g / cm 3 Fiber expansion agent: MPC polymer fiber expansion agent, with a 7-day restricted expansion rate in water of 0.029% and a 21-day restricted expansion rate in air of -0.010%, purchased from Henan Aluminum City Jueneng Industry Co., Ltd.; The accelerating agent is N(II) alkali-free liquid accelerating agent, with an initial setting time of 4.25 min, a final setting time of 9.43 min, a solid mass fraction of about 52.5%, a density of 1.379 g / cm3, and a pH value of 2.7, purchased from Guangzhou Gongshi Chemical Materials Co., Ltd.

[0053] The first material provided by the embodiments of the present application will be introduced in detail below.

[0054] Preparation Examples

[0055] Preparation Example 1

[0056] Preparation of the first material: Take 20 parts of cement, 10 parts of vitrified microspheres, 1 part of waterproof agent, 1 part of composite expansion material, 20 parts of admixture, 5 parts of modified polyvinyl alcohol fiber, 0.5 part of water reducer, 1 part of early strength agent, 2 parts of thixotropic agent, 80 parts of high-strength aggregate, 3 parts of accelerating agent, and 10 parts of water.

[0057] Among them, the waterproofing agent includes sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid, and sodium dodecyl sulfate with a weight ratio of 30:5:1:1.

[0058] The preparation method of the modified polyvinyl alcohol fiber includes the following steps:

[0059] Soak 1 kg of polyvinyl alcohol fiber in 2 L of sodium hydroxide solution with a mass fraction of 25%, stir for 2 h, wash with water, then immerse in absolute ethanol, soak for 1 h, and dry to obtain a modified fiber precursor;

[0060] Ultrasonically disperse carbon nanotubes in 1 L of ethanol, then add the modified fiber precursor, stir for 1.5 h, and dry to obtain a modified fiber intermediate;

[0061] Dissolve graphene oxide in 1 L of acetic acid, then add the modified fiber intermediate, stir for 3 h, and then dry to obtain the modified polyvinyl alcohol fiber;

[0062] The weight ratio of the polyvinyl alcohol fiber, carbon nanotubes, and graphene oxide is 1:0.5:0.4.

[0063] The composite expansion material is prepared by the following method: By weight, take 100 parts of fiber expansion agent, 10 parts of bentonite, 1 part of potassium alum, and 4 parts of zeolite powder, add 100 parts of water, grind at a speed of 50 r / min for 30 min, and then dry at a temperature of 60 °C for 12 h to obtain the core material;

[0064] Take 40 parts of sodium methacrylate and 2 parts of sodium alginate, add them to 200 parts of water, stir evenly, heat to 60 °C and keep stirring for 40 min, add 5 parts of polyvinyl alcohol, then raise the temperature to 85 °C, and stir at a speed of 3000 r / min for 20 min to obtain the coating solution;

[0065] Put the core material into a coating granulator, spray the coating solution onto the core material. The rotation speed of the coating granulator is 15 r / min, the temperature is 70 °C, and the liquid spraying speed is 15 g / min. After coating, dry the obtained coated particles by hot air until completely cured, and then cool at room temperature to obtain the composite expansion material. Among them, the coating material in the composite expansion material accounts for 1% of the weight of the core material.

[0066] Preparation Example 2

[0067] Preparation Example 2 also provides a first material. Different from Preparation Example 1: 40 parts of cement, 13 parts of vitrified microspheres, 5 parts of waterproofing agent, 3 parts of composite expansion material, 30 parts of admixture, 10 parts of modified polyvinyl alcohol fiber, 1 part of water reducing agent, 3 parts of early strength agent, 3 parts of thixotropic agent, 100 parts of high-strength aggregate, 4 parts of accelerating agent, and 20 parts of water.

[0068] Preparation Example 3

[0069] Preparation Example 3 also provides a first material. Different from Preparation Example 1, it contains 60 parts of cement, 15 parts of vitrified microspheres, 10 parts of waterproofing agent, 5 parts of composite expansion material, 40 parts of admixture, 15 parts of modified polyvinyl alcohol fiber, 1.5 parts of water reducing agent, 5 parts of early strength agent, 4 parts of thixotropic agent, 120 parts of high-strength aggregate, 6 parts of accelerating agent and 30 parts of water.

[0070] Preparation Example 4

[0071] Preparation Example 4 also provides a first material. Different from Preparation Example 1, the weight ratio of modified polyvinyl alcohol fiber, vitrified microspheres, waterproofing agent and composite expansion material in the first material is 10:13:6:3.

[0072] Preparation Example 5

[0073] Preparation Example 5 also provides a first material. Different from Preparation Example 1, the weight ratio of vitrified microspheres, waterproofing agent and composite expansion material in the first material is 8:12:7:4.

[0074] Preparation Example 6

[0075] Preparation Example 6 also provides a first material. Different from Preparation Example 1, the weight ratio of polyvinyl alcohol fiber, carbon nanotube and graphene oxide in the modified polyvinyl alcohol fiber is 1:0.6:0.5.

[0076] Preparation Example 7

[0077] Preparation Example 7 also provides a first material. Different from Preparation Example 1, the weight ratio of polyvinyl alcohol fiber, carbon nanotube and graphene oxide in the modified polyvinyl alcohol fiber is 1:0.8:0.6.

[0078] Preparation Example 8

[0079] Preparation Example 8 also provides a first material. Different from Preparation Example 1, the waterproofing agent includes sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate with a weight ratio of 45:10:4:2.

[0080] Preparation Example 9

[0081] Preparation Example 9 also provides a first material. Different from Preparation Example 1, the waterproofing agent includes sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate with a weight ratio of 60:15:5:3.

[0082] Preparation Example 10

[0083] Preparation Example 10 also provides a first material. Different from Preparation Example 1, the waterproofing agent includes sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid, and sodium dodecyl sulfate with a weight ratio of 40:10:3:1.

[0084] Preparation Example 11

[0085] Preparation Example 11 also provides a first material. Different from Preparation Example 1, the waterproofing agent includes sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid, and sodium dodecyl sulfate with a weight ratio of 50:13:4:2.

[0086] Preparation Example 12

[0087] Preparation Example 12 also provides a first material. Different from Preparation Example 1, the waterproofing agent does not contain sodium orthosilicate tetrahydrate.

[0088] Preparation Example 13

[0089] Preparation Example 13 also provides a first material. Different from Preparation Example 1, the waterproofing agent does not contain anhydrous sodium carbonate.

[0090] Preparation Example 14

[0091] Preparation Example 14 also provides a first material. Different from Preparation Example 1, the waterproofing agent does not contain ethylenediaminetetraacetic acid.

[0092] Preparation Example 15

[0093] Preparation Example 15 also provides a first material. Different from Preparation Example 1, the waterproofing agent does not contain sodium dodecyl sulfate.

[0094] Preparation Example 16

[0095] Preparation Example 16 also provides a first material. Different from Preparation Example 1, the composite expansion material is prepared by the following method: By weight, take 100 parts of fiber expansion agent, 12 parts of bentonite, 3 parts of potassium alum, and 6 parts of zeolite powder. After adding 100 parts of water, grind at a speed of 50 r / min for 30 min, and then dry at a temperature of 60 °C for 12 h to obtain the core material;

[0096] Take 45 parts of sodium methacrylate and 3 parts of sodium alginate, add them to 250 parts of water, stir evenly, heat to 60 °C, keep stirring for 30 min, add 7 parts of polyvinyl alcohol, then raise the temperature to 85 °C, and stir at a speed of 3000 r / min for 20 min to obtain the coating liquid;

[0097] Put the core material into a coating granulator, spray the coating liquid onto the core material. The rotation speed of the coating granulator is 15 r / min, the temperature is 60 °C, and the liquid spraying speed is 16 g / min. After coating, the obtained coated particles are dried by hot air until completely cured, and then cooled at room temperature to obtain the composite expansion material. Among them, the coating material in the composite expansion material accounts for 2% of the weight of the core material.

[0098] Preparation Example 17

[0099] Preparation Example 17 also provides a first material. Different from Preparation Example 1, the composite expansion material is prepared by the following method: By weight, take 100 parts of fiber expansion agent, 15 parts of bentonite, 5 parts of potassium alum, and 8 parts of zeolite powder. After adding 100 parts of water, grind at a speed of 50 r / min for 30 min, and then dry at a temperature of 60 °C for 12 h to obtain the core material;

[0100] Take 50 parts of sodium methacrylate and 5 parts of sodium alginate, add them to 300 parts of water, stir evenly, heat to 80 °C, keep stirring for 50 min, add 10 parts of polyvinyl alcohol, then raise the temperature to 90 °C, and stir at a speed of 4000 r / min for 30 min to obtain the coating liquid;

[0101] Put the core material into a coating granulator, spray the coating liquid onto the core material. The rotation speed of the coating granulator is 20 r / min, the temperature is 70 °C, and the liquid spraying speed is 18 g / min. After coating, the obtained coated particles are dried by hot air until completely cured, and then cooled at room temperature to obtain the composite expansion material. Among them, the coating material in the composite expansion material accounts for 4% of the weight of the core material.

[0102] Preparation Example 18

[0103] Preparation Example 18 also provides a first material. Different from Preparation Example 1, the fiber expansion agent is not added to the core material of the composite expansion material.

[0104] Preparation Example 19

[0105] Preparation Example 19 also provides a first material. Different from Preparation Example 1, the bentonite is not added to the core material of the composite expansion material.

[0106] Preparation Example 20

[0107] Preparation Example 20 also provides a first material. Different from Preparation Example 1, the potassium alum is not added to the core material of the composite expansion material.

[0108] Preparation Example 21

[0109] Preparation Example 21 also provides a first material. Different from Preparation Example 1, the zeolite powder is not added to the core material of the composite expansion material.

[0110] Preparation Example 22

[0111] Preparation Example 22 also provides a first material. Different from Preparation Example 1, the outer periphery of the core material of the composite expansion material is not coated. That is, the composite expansion material is prepared by the following method: taking 100 parts by weight of fiber expansion agent, 10 parts of bentonite, 1 part of potassium alum, and 4 parts of zeolite powder, adding 100 parts of water, grinding at a speed of 50 r / min for 30 min, and then drying at a temperature of 60 °C for 12 h.

[0112] Comparative Example 1

[0113] Comparative Example 1 also provides a first material. Different from Preparation Example 1, the composite expansion material is not added.

[0114] Comparative Example 2

[0115] Comparative Example 2 also provides a first material. Different from Preparation Example 1, the waterproof agent is not added.

[0116] Comparative Example 3

[0117] Comparative Example 3 also provides a first material. Different from Preparation Example 1, the vitrified microspheres are not added.

[0118] Comparative Example 4

[0119] Comparative Example 4 also provides a first material. Different from Preparation Example 1, polyvinyl alcohol fiber is used to replace the modified polyvinyl alcohol fiber.

[0120] Comparative Example 5

[0121] Comparative Example 5 also provides a first material. Different from Preparation Example 1, carbon nanotubes are not added to the modified polyvinyl alcohol fiber.

[0122] Comparative Example 6

[0123] Comparative Example 6 also provides a first material. Different from Preparation Example 1, graphene oxide is not added to the modified polyvinyl alcohol fiber.

[0124] The mechanical properties of the first materials in Preparation Examples 1 - 22 and Comparative Examples 1 - 6 were tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T 50081 - 2019, and the standard curing age was 7 and 28 d.

[0125] Chloride ion diffusion coefficient: The chloride ion diffusion coefficient of the standard test block was tested according to the RCM method in the "Standard for Test Methods of Long - term Performance and Durability of Ordinary Concrete" GB / T50082 - 2009.

[0126] Water penetration resistance: According to the step-by-step pressure method in the "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" GB / T50082-2009, the water penetration depth of standard specimens is tested.

[0127] Water penetration durability test: According to the requirements of Appendix B in the "Technical Specification for Application of Shotcrete" JGJ / T372-2016, prepare shotcrete specimens, take out the specimens after curing in a standard curing room for 28 h; place the cured specimens in a container, add 35 wt% brine to the container so that the brine completely covers the upper end surface of the specimens, store them at (40 ± 2) °C for 3 months, and during the storage period, replenish 35 wt% brine at any time so that the brine always covers the upper end surface of the specimens; after 3 months, take out the specimens, rinse the surface of the specimens with clean water, wipe off the moisture on the surface of the specimens, and then place the specimens at (25 ± 2) °C and 65% RH for 3 months to obtain aged specimens; test the water penetration depth of the aged specimens according to the step-by-step pressure method in the "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" GB / T50082-2009.

[0128] Test the cracking area of the concrete according to GB / T 50082-2009, and the test results are shown in Table 1.

[0129] Table 1 Test results of the first materials obtained in Preparation Examples 1-22 and Comparative Examples 1-6

[0130]

[0131]

[0132] It can be seen from the data in Table 1 that the first material used as concrete obtained in Preparation Examples 1-22 of the present application has high compressive strength, the chloride ion diffusion coefficient is less than 0.06×10 -12 m 2 ·S -1 , and the cracking area is small, that is, the possibility of concrete cracking is small, the water penetration depths of the standard specimens and the aged specimens are small, and it has excellent water penetration resistance.

[0133] It can be seen from Preparation Examples 1-5 and Comparative Examples 1-4 in combination with the data in Table 1 that the compressive strength of the concrete in Preparation Examples 1-5 of the present application is significantly better than that of Comparative Examples 1-3, and the chloride ion diffusion coefficient and the water penetration depth are significantly lower than those of Comparative Examples 1-3. This shows that when the weight ratio of the modified polyvinyl alcohol fiber, vitrified microbeads, waterproofing agent and composite expansion material is (5-10):(12-13):(5-7):(3-4), compared with the first material lacking or replacing any of the modified polyvinyl alcohol fiber, vitrified microbeads, waterproofing agent and composite expansion material components, it significantly improves the mechanical strength and impermeability of the concrete. And when the weight ratio of the modified polyvinyl alcohol fiber, vitrified microbeads, waterproofing agent and composite expansion material is 8:12:7:4, the mechanical strength and impermeability of the concrete are the best. This may be because, due to the different physical shapes such as the appearance morphology, internal structure, surface properties and particle gradation of the modified polyvinyl alcohol fiber, vitrified microbeads, waterproofing agent and composite expansion material, a morphological effect can be generated, and the sizes of different morphologies are interlaced with each other. The modified polyvinyl alcohol fiber has a special-shaped structure and can adhere to each other with the materials, acting as an aggregate; moreover, the size of the modified polyvinyl alcohol fiber is small and it is easy to form a dense random network, acting as a reinforcing bar; while the spherical solid vitrified microbeads can improve the dispersion performance of the modified polyvinyl alcohol fiber and make the fiber adhere tightly to the cement. The above components are evenly distributed in the concrete to form an interactive network, effectively reducing the generation of concrete pores, improving the impermeability, and preventing the generation and development of cracks.

[0134] It can be seen from Preparation Examples 6-7 and Comparative Examples 5-6 in combination with Table 2 that the ratio of polyvinyl alcohol fiber, carbon nanotube and graphene oxide in the modified polyvinyl alcohol fiber can affect the mechanical strength and impermeability of the concrete. Among them, when the weight ratio of polyvinyl alcohol fiber, carbon nanotube and graphene oxide in the modified polyvinyl alcohol fiber in Preparation Example 6 is 1:0.6:0.5, the 7-day compressive strength of the concrete reaches 99 Mpa, the 28-day compressive strength reaches 183 Mpa, the chloride ion diffusion coefficient is 0.02×10 - 12 m 2 ·S -1 , the water penetration depth of the standard specimen is 1.4 mm, the water penetration depth of the aged specimen is 13.2 mm, and the cracking area is 90 mm 2 / m 2 . And it can be seen from Preparation Example 1 and Comparative Examples 4-6 in combination with Table 2 that the impermeability of the aged specimen of the concrete in Preparation Example 1 is better than that of Comparative Examples 4-6, indicating that when the modified polyvinyl alcohol fiber is modified by compounding carbon nanotube and graphene oxide, it has a good synergistic effect and can improve the compressive strength and impermeability of the concrete.

[0135] From the data comparison between Comparative Example 4 and Preparation Example 1 in Table 1, it can be seen that the modified polyvinyl alcohol fibers added to the concrete in this application can significantly improve the compressive strength of the concrete compared with the unmodified polyvinyl alcohol fibers. The reason may be that the modified polyvinyl alcohol fibers are more easily dispersed in the components such as cement colloid and coarse aggregate in the concrete, the interfacial action with the cement colloid is enhanced, and it becomes a bridge connecting the cement colloid and the aggregate, enhancing its bonding effect. When the concrete is compressed, it is not easy to break and fracture, improving the overall stability of the concrete; at the same time, the impermeability of the concrete is also improved. The adsorption of carbon nanotubes and graphene oxide on the surface of the polyvinyl alcohol fibers in the modified polyvinyl alcohol fibers has a significant impact on the compressive strength and impermeability of the concrete; on the one hand, the reason may be that the carbon nanotubes and graphene oxide are adsorbed on the polyvinyl alcohol fibers in a lamellar structure through π-π stacking, changing the surface composition of the polyvinyl alcohol fibers, and giving full play to the impermeability and crack resistance performance of the polyvinyl alcohol fibers; at the same time, the interaction between the polyvinyl alcohol fibers and the cement colloid is also enhanced; on the other hand, the lamellar structure of the carbon nanotubes and graphene oxide itself may also have the effect of blocking capillary pores to achieve the effect of waterproofing and impermeability.

[0136] Combined with Preparation Example 1, 8-11 and Table 2, it can be seen that the ratio of sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate in the waterproofing agent can affect the mechanical properties and impermeability of the concrete. Among them, the 7-day and 28-day compressive strengths of the concrete in Preparation Example 8 are higher than those in Preparation Example 1, 9-11, the chloride ion diffusion coefficient and the water penetration depth (standard specimen, aged specimen) of Preparation Example 8 are lower than those in Preparation Example 1, 9-11, and the water penetration depth of the aged specimen in Preparation Example 8 is significantly lower than that in Preparation Example 1, indicating that when the ratio of sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate in the waterproofing agent is 45:10:4:2, it can ensure the mechanical properties and impermeability of the concrete in the early, middle and late stages.

[0137] From Preparation Example 1, 12-15 and Table 1, it can be seen that the lack of any component of sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate in the waterproofing agent will cause the 7-day and 28-day compressive strengths of the concrete to decrease, and the chloride ion diffusion coefficient and the water penetration depth to increase. Among them, the degree of influence on the mechanical properties and impermeability of the concrete is sodium orthosilicate tetrahydrate > anhydrous sodium carbonate > ethylenediaminetetraacetic acid > sodium dodecyl sulfate, indicating that sodium orthosilicate tetrahydrate has an obvious influence on the compressive and impermeability properties. The lack of anhydrous sodium carbonate, ethylenediaminetetraacetic acid or sodium dodecyl sulfate will cause the compressive and impermeability properties of the concrete to decline to a certain extent, indicating that using a waterproofing agent composed of a compound of sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate can significantly improve the mechanical strength and impermeability of the concrete compared with the effect of not using one of them for compounding.

[0138] It can be seen from Preparation Examples 1, 16 - 17 and in combination with Table 1 that the addition of the composite expansion material can improve the compactness of concrete in the early stage, thus slightly increasing the compressive strength and chloride ion penetration resistance of the concrete; in the later stage, it can also significantly improve the water permeability resistance of the aged concrete specimens, indicating that the addition of the composite expansion material can significantly improve the durability of the concrete.

[0139] It can be seen from Preparation Examples 1, 18 - 21 and in combination with Table 1 that the lack of any one component of fiber expansion agent, bentonite, potassium alum or zeolite powder in the core material of the composite expansion material will cause the decline of the compressive and impermeability performance of the concrete, indicating that the compounding of fiber expansion agent, bentonite, potassium alum and zeolite powder can significantly improve the mechanical strength and impermeability performance of the concrete compared with the effect of not using one of them for compounding.

[0140] Combined with Preparation Example 22, Preparation Example 1 and Table 2, it can be seen that the compressive strength of the concrete in Preparation Example 22 and the impermeability performance of the standard specimens are better than those in Preparation Example 1, but the water permeability resistance of its aged specimens is worse than that in Preparation Example 1, indicating that when only the core material is added, it can improve the early strength and impermeability performance of the concrete, but the improvement effect on the later impermeability performance of the concrete is not significant; therefore, if only for improving the early impermeability and compressive strength of the concrete, the core material can be directly added, but if for improving the later impermeability performance of the concrete, the core material needs to be coated; and if for significantly improving the early and later impermeability performance of the concrete at the same time, a certain amount of the core material and the coated composite expansion material can be added simultaneously.

[0141] In this way, the first material is applied to the support system through spraying construction, making the construction fast and efficient. Also, because the first material has high impermeability and waterproof performance and compressive strength, it can quickly establish the support strength while solving the influence of deep groundwater penetration and high water pressure on the roadway structure.

[0142] Preparation Example 23

[0143] Preparation of the second material: Take 100 parts of cement, 210 parts of rubber particles, 60 parts of admixture, 10 parts of impermeable fiber, 3 parts of foaming agent, 3 parts of water reducing agent, 100 parts of water and 15 parts of early strength agent; mix the above raw materials evenly to obtain the first material mortar; among them, the impermeable fiber is composed of polyester fiber; the length of the polyester fiber is 5 - 7 mm, and the diameter is 15 - 20 μm; the early strength agent includes acyloxy silane, sodium thiosulfate and triethanolamine with a weight ratio of 3:4:2.

[0144] Example

[0145] Example 1

[0146] Figure 1The figure shows a schematic diagram of the waterproof support structure constructed by the first underground roadway waterproof support method provided in Embodiment 1 of the present application. Refer to Figure 1 , an underground roadway waterproof support method, comprising the following steps:

[0147] S1. After constructing bolt holes on the surface 1 of the structure to be supported after draining water and installing bolts 2, install a first steel mesh 3 and a second steel mesh 4 on the bolts 2. In other words, use the bolts 2 to fix the first steel mesh 3 and the second steel mesh 4.

[0148] Exemplarily, the surface of the structure to be supported 1 can be any one of the surface of a coal mine roadway, the surface of a foundation pit, a highway roadway, and a hydraulic tunnel. Hereinafter, the surface of a coal mine roadway will be taken as an example for exemplary illustration, but it should be understood that the present application is not limited thereto.

[0149] Exemplarily, the bolt 2 is a deformed steel bolt with a specification of Φ0.02×2.00 m; one end of the bolt is rolled with threads, the thread length is 30 cm, the bolt hole depth is 170 cm, the anchoring length is 120 cm, and the exposed length is 80 cm. It is used as both temporary support and can hang the first steel mesh.

[0150] Exemplarily, the main support bars of the first steel mesh 3 are made of Φ22 deformed steel bars, with a longitudinal spacing of 20 cm, the distribution bars are made of Φ14 deformed steel bars, with a circumferential spacing of 25 cm, and the stirrups are made of round steel bars, with a spacing of 25 cm.

[0151] In an optional implementation manner, reinforcing ribs (not shown in the figure) are provided on the first steel mesh 3. The reinforcing ribs are made of Φ14 deformed steel bars and are arranged at intervals with respect to the main support bars of the first steel mesh.

[0152] It should be noted that the second steel mesh 4 includes a layer of steel mesh and a layer of mine-use flame-retardant plastic mesh, and the mine-use flame-retardant plastic mesh is located between the first steel mesh and the steel mesh. Exemplarily, the mesh size of the second steel mesh 4 is smaller than the mesh size of the first steel mesh 3. For example, the second steel mesh 4 uses Φ12 deformed steel bars, with a longitudinal spacing of 10 cm, the distribution bars use Φ10 deformed steel bars, with a circumferential spacing of 12 cm, and the stirrups use round steel bars, with a spacing of 25 cm. Optionally, the mine-use flame-retardant plastic mesh can be arranged in a double layer to reduce slurry leakage when spraying the first material.

[0153] S2. Spray a first material on the surface of the second steel mesh 4 to construct a support layer 5, and reserve grouting holes (not shown in the figure) on the support layer 5. The support layer 5 is used to provide high-strength and stable support for the roadway.

[0154] Exemplarily, a first material is sprayed on the surface of the second steel mesh 4 to construct a support layer 5, including: taking 20 parts of cement, 10 parts of vitrified microspheres, 1 part of waterproofing agent, 1 part of composite expansion material, 20 parts of admixture, 5 parts of modified polyvinyl alcohol fiber, 0.5 part of water reducing agent, 2 parts of thixotropic agent, 80 parts of high-strength aggregate and 10 parts of water according to the preset weight parts, such as the first material in Preparation Example 1, and stirring evenly to obtain a first concrete preliminary mixture. Subsequently, when pumping the first concrete preliminary mixture, 3 parts of the quick-setting agent and 1 part of the early-strength agent are pumped into the pipeline at a position 1-3 m in front of the concrete spray gun. After being evenly mixed by the pipeline mixer, it is sprayed on the surface of the second steel mesh through the concrete spray gun to construct the support layer 5, which is used to provide high-strength waterproof and anti-seepage support for the roadway.

[0155] S3. After the support layer 5 has finally set, grout injection of the second material is carried out between the support layer and the surface of the roadway to be supported through the grouting holes to construct a buffer layer 6, and the buffer layer 6 is used to provide a buffer for the deformation and movement of the roadway.

[0156] Optionally, the second material for constructing the buffer layer 23 can be a material with good elasticity and compressive strength, which can effectively absorb and disperse stress. For example, lightweight foam concrete prepared using lightweight aggregates (such as expanded perlite, ceramsite or rubber particles) can reduce the weight of the overall structure and at the same time provide a good buffering effect. Exemplarily, the second material is the second material provided in Preparation Example 10.

[0157] It can be understood that the gap between two adjacent support layers serves as an expansion joint, and a back - pasted waterproof structure and / or an embedded water - bag waterproof structure is constructed at the expansion joint. Among them, the back - pasted waterproof structure refers to waterproof treatment on the outer side of the expansion joint (usually on the outer surface of the support structure) through special materials. The waterproof layer and the structure form a back - pasted manner to achieve the purpose of preventing water from penetrating through the expansion joint. Exemplarily, the back - pasted waterproof layer is usually composed of high - quality waterproof membranes, water - stop belts, waterproof rubber strips or self - adhesive waterproof materials, etc. These materials adhere to the expansion joint and, through the sealing effect, isolate the entry of moisture. When groundwater or seepage pressure acts on the waterproof layer, the waterproof material can produce a "self - healing" effect, that is, even if there are tiny cracks in the waterproof layer, it can automatically repair itself to prevent water penetration. The embedded water - bag waterproof structure is a method of embedding a waterproof device (usually a water bag or other water - filled materials) in the middle layer of the structure to form an effective waterproof isolation layer. The embedded water - bag is usually embedded in the expansion joint or joint position during the construction of the structure, and the water - filled effect of the water bag is used to resist the external water pressure. For example, during construction, a water bag with good waterproof performance is embedded in the middle of the expansion joint. Once the water bag is filled with water, it can bear the external seepage pressure. In this way, the water bag will expand under the action of water pressure, further enhancing the sealing effect with the structure and forming a water - proof layer to prevent water from entering the roadway or other underground spaces through the gap. It should be noted that the above - mentioned waterproof membranes, water - stop belts, waterproof rubber strips, self - adhesive waterproof materials, water bags or other water - filled materials can all be obtained commercially, and no detailed introduction is given here in this application.

[0158] In this embodiment, first, the first material is sprayed to form the support layer 5, and the material is provided with grouting holes after initial setting. Subsequently, the second material is injected through the grouting holes to form the buffer layer 6. In this construction method, in the case where the buffer layer is not constructed, through the configuration of the wire mesh sheets in the second wire mesh 4 and the mine anti-flame-retardant plastic mesh, the preparatory work for the spraying construction of the support layer 5 is formed. Subsequently, the support layer 5 is quickly sprayed and constructed. Since the support layer 5 has a certain distance from the roadway surface, the initial deformation of the roadway will not generate too much pressure on the support layer 5. Then, the grouting buffer layer 6 is constructed, and the yielding initial support that effectively connects the bolt 2 and the buffer layer 6 is used to effectively utilize the bearing capacity of the surrounding rock, significantly improve the bearing capacity of the initial support, control the large deformation of the surrounding rock, more effectively cope with the large deformation of the high in-situ stress soft rock roadway, ensure the construction safety. Moreover, compared with the casting construction, the wet spraying construction can effectively improve the construction efficiency. At the same time, the buffer layer 6 constructed by the second material in Preparation Example 10 has high compressibility, high ductility and a certain bearing capacity, and can better absorb the deformation energy generated by the surrounding rock after the support layer is constructed under the reaction force provided by the support layer 5, and can generate a yielding deformation of 100 - 150 cm. For the unpredictable deformation load of the high in-situ stress soft rock formation, when the yielding initial support generates a large deformation, under the support of the support layer 5, the rubber particles of the buffer layer 6 can generate a compressive deformation. Under the combined action of the bonding and connection of cement and anti-seepage fibers, the buffer layer can generate a certain compressive deformation without cracking, absorb the energy generated by the large deformation load of the surrounding rock, and does not affect its support performance. Similarly, the support layer constructed by the first material in Preparation Example 2 has excellent stress-strain capacity, that is, the second concrete material can support a relatively large initial stress and has excellent deformation ability. On the other hand, in addition to being able to withstand a relatively high pressure ≥ 120 MPa, since the support layer 5 is added with a high dosage of reinforcing fibers, the support layer 5 has good crack resistance, so that after the support layer 5 bears the pressure exceeding its own compressive strength, it can still maintain an unbroken state, and can effectively prevent the generation and expansion of cracks, thereby improving the support ability.

[0159] In this implementation plan, the method of combining "leaving enough deformation space, being flexible first and then rigid, and strengthening the support" is adopted to effectively control the large deformation of the soft rock, ensure the construction safety of the roadway, and greatly reduce the construction risk. At the same time, in the construction, the wet shotcrete method is adopted to construct the support layer and the grouting to form the buffer layer. While ensuring the construction efficiency, the buffer layer can fill the gap between the support layer and the roadway, play a role in resisting part of the deformation pressure, and the support layer plays its strengthening role, jointly forming a systematic support system for controlling the large deformation of this roadway to further effectively control the large deformation of the soft rock. Moreover, since the support layer 5 has excellent waterproof and anti-seepage performance, it can effectively solve the influence of deep groundwater seepage and high water pressure on the roadway structure.

[0160] Example 2

[0161] Figure 2 The figure shows a schematic diagram of a waterproof support structure constructed by the second underground roadway waterproof support method provided in Example 2 of the present application. Refer to Figure 2 , an underground roadway waterproof support method, comprising the following steps:

[0162] S1. After constructing bolt holes on the surface of the structure 1 to be supported after draining water and installing bolts 2, a second steel mesh 4 is arranged on the bolts 2. In other words, the second steel mesh 4 is fixed by using the bolts 2.

[0163] Exemplarily, the surface of the structure 1 to be supported can be any one of the surface of a coal mine roadway, the surface of a foundation pit, a highway roadway, and a hydraulic tunnel. Hereinafter, the surface of a coal mine roadway will be taken as an example for illustrative purposes, but it should be understood that the present application is not limited thereto.

[0164] Exemplarily, the bolt 2 is a deformed steel bolt with a specification of Φ0.02×2.00m; one end of the bolt is rolled with threads, the thread length is 30cm, the bolt hole depth is 170cm, the anchoring length is 120cm, and the exposed length is 80cm, which is used as both temporary support and can be used to hang the first steel mesh.

[0165] It should be noted that the second steel mesh 4 includes a layer of steel mesh and a layer of mine-use flame-retardant plastic mesh, and the mine-use flame-retardant plastic mesh is located between the first steel mesh and the surface of the structure 1 to be supported. Exemplarily, the second steel mesh 4 uses Φ12 deformed steel bars, the longitudinal spacing is 10cm, the distribution bars use Φ10 deformed steel bars, the circumferential spacing is 12cm, and the stirrups use round steel, with a spacing of 25cm. Optionally, the mine-use flame-retardant plastic mesh can be arranged in a double layer to reduce the leakage of slurry when spraying the first material.

[0166] S2. Spray a first material on the surface of the second steel mesh 4 to construct a support layer 5, and the support layer 5 is used to provide high-strength and stable support for the roadway.

[0167] Exemplarily, spraying a first material on the surface of the second steel mesh 4 to construct a support layer 5 includes: according to the preset weight parts, for example, the first material in Preparation Example 1, taking 20 parts of cement, 10 parts of vitrified microspheres, 1 part of waterproof agent, 1 part of composite expansion material, 20 parts of admixture, 5 parts of modified polyvinyl alcohol fiber, 0.5 part of water reducing agent, 2 parts of thixotropic agent, 80 parts of high-strength aggregate and 10 parts of water, stirring evenly to obtain the first concrete initial mixture. Subsequently, when pumping the first concrete initial mixture, 3 parts of the quick-setting agent and 1 part of the early-strength agent are pumped into the pipeline at a position 1-3m in front of the concrete spray gun. After being mixed evenly by the pipeline mixer, it is sprayed on the surface of the second steel mesh through the concrete spray gun to construct the support layer 5, which is used to provide high-strength waterproof and anti-seepage support for the underground roadway.

[0168] It is understandable that the gap between two adjacent support layers serves as an expansion joint, and a back-adhered waterproof structure and / or an embedded water bag waterproof structure are constructed at the expansion joint. Among them, the back-adhered waterproof structure refers to waterproof treatment with special materials on the outer side of the expansion joint (usually on the outer surface of the support structure), and the waterproof layer forms a back-adhered manner with the structure to achieve the purpose of preventing water from penetrating through the expansion joint. Exemplarily, the back-adhered waterproof layer is usually composed of high-quality waterproof membranes, waterstops, waterproof rubber strips or self-adhesive waterproof materials, etc. These materials adhere to the expansion joint and isolate moisture from entering through sealing. When groundwater or seepage pressure acts on the waterproof layer, the waterproof material can produce a "self-healing" effect, that is, even if there are tiny cracks in the waterproof layer, it can automatically repair to prevent water penetration. The embedded water bag waterproof structure is a method of embedding a waterproof device (usually a water bag or other water-filled materials) in the middle layer of the structure to form an effective waterproof isolation layer. The embedded water bag is usually embedded in the expansion joint or joint position during the construction of the structure, and the water pressure of the water bag is used to resist the external water pressure. For example, during construction, a water bag with good waterproof performance is embedded in the middle of the expansion joint. Once the water bag is filled with water, it can withstand the external seepage pressure. In this way, the water bag will expand under the action of water pressure, further enhancing the sealing effect with the structure and forming a waterproof layer to prevent water from entering the roadway or other underground spaces through the gap. It should be noted that the above-mentioned waterproof membranes, waterstops, waterproof rubber strips, self-adhesive waterproof materials, water bags or other water-filled materials can all be obtained commercially, and no detailed introduction will be made here in this application.

[0169] In this embodiment, compared with Embodiment 1, the steps of constructing the first steel mesh 3 and the buffer layer 6 are missing. Therefore, in the support of roadways with little deformation, rapid support can be achieved while having better anti-seepage and waterproof performance and support stability. Construction workers can flexibly select the support construction method according to the deformation of the underground roadway, improving the applicability of the support construction method of this application.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application. Those of ordinary skill in the art should understand that although this application has been described in detail with reference to the foregoing embodiments, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of this application.

Claims

1. A waterproof support method for underground tunnels, characterized in that: The following steps are involved: Anchor rods are constructed on the surface of the tunnel to be supported after water discharge, and a first steel mesh and a second steel mesh are installed on the constructed anchor rods; wherein reinforcing ribs are arranged at intervals on the first steel mesh; the mesh size of the second steel mesh is smaller than the mesh size of the first steel mesh, and the second steel mesh includes a layer of steel mesh and a layer of anti-flame retardant plastic mesh for mining, and the anti-flame retardant plastic mesh for mining is located between the first steel mesh and the steel mesh; The first material is sprayed on the surface of the second steel mesh to construct a support layer, and grouting holes are reserved on the support layer, wherein the support layer is used to provide high-strength waterproof and anti-seepage support for the tunnel; After the supporting layer is finally set, grouting of a second material is performed between the supporting layer and the surface of the roadway to be supported through the grouting hole to construct a buffer layer, wherein the buffer layer is used to provide a buffer for the deformation and movement of the roadway; The gap between two adjacent supporting layers is used as an expansion joint, and a back-sticking waterproof structure and / or a middle-buried water bag waterproof structure are constructed at the expansion joint; The first material comprises the following components in parts by weight: 20-60 parts of cement, 10-15 parts of vitrified microspheres, 1-10 parts of waterproofing agent, 1-5 parts of composite expansion material, 20-40 parts of admixture, 0.5-1.5 parts of water reducing agent, 1-5 parts of early strength agent, 2-4 parts of thixotropic agent, 80-120 parts of high-strength aggregate, 3-6 parts of accelerating agent, 5-15 parts of modified polyvinyl alcohol fiber and 10-30 parts of water; The modified polyvinyl alcohol fiber preparation method comprises the following steps: The polyvinyl alcohol fiber is immersed in a sodium hydroxide solution, stirred for 1-3 hours, washed with water, immersed in anhydrous ethanol, immersed for 1-2 hours, and dried to obtain a modified fiber precursor; Ultrasonic dispersion of carbon nanotubes in ethanol, then adding the modified fiber precursor, stirring for 1-2 hours, and drying to obtain a modified fiber intermediate; The graphene oxide is dissolved in acetic acid, and then the modified fiber intermediate is added, stirred for 2-5 hours, and then dried to obtain the modified polyvinyl alcohol fiber; The weight ratio of the polyvinyl alcohol fiber, the carbon nanotube and the graphene oxide is 1:(0.5-0.8):(0.4-0.6).

2. The support method according to claim 1, characterized in that: The weight ratio of the polyvinyl alcohol fiber, the carbon nanotube and the graphene oxide is 1:0.6:0.

5.

3. The support method according to claim 1, characterized in that: The weight ratio of the glass microspheres, the waterproofing agent and the composite expansion material in the first material is (12-13): (5-7): (3-4).

4. The support method according to claim 3, characterized in that: The weight ratio of the vitrified microspheres, the waterproofing agent and the composite expansion material in the first material is 12:7:

4.

5. The support method according to claim 1, characterized in that: The waterproofing agent comprises sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate in a weight ratio of (30-60):(5-15):(1-5):(1-3).

6. The support method according to claim 5, characterized in that: The waterproofing agent comprises sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate in a weight ratio of (40-50):(10-15):(3-5):(1-3).

7. The support method according to claim 6, characterized in that: The waterproofing agent comprises sodium orthosilicate tetrahydrate, anhydrous sodium carbonate, ethylenediaminetetraacetic acid and sodium dodecyl sulfate in a weight ratio of 45:10:4:

2.

8. The support method according to claim 1, characterized in that: The composite expansion material is formed by coating a core material on its periphery, wherein the coating material accounts for 1-4% of the weight of the core material; the core material comprises the following raw materials in parts by weight: 100 parts of a fiber expansion agent, 10-15 parts of bentonite, 1-5 parts of potassium aluminum sulfate and 4-8 parts of zeolite powder; the coating material comprises the following raw materials in parts by weight: 10-20 parts of sodium methacrylate, 2-5 parts of sodium alginate and 5-10 parts of polyvinyl alcohol.

9. The support method according to claim 8, characterized in that: The composite expansion material is prepared by the following method: taking 100 parts of fiber expansion agent, 10-15 parts of bentonite, 1-5 parts of potassium aluminum sulfate and 4-8 parts of zeolite powder by weight, grinding and drying to obtain a core material; Take 40-50 parts of sodium methacrylate and 2-5 parts of sodium alginate and add them to 200-300 parts of water, stir evenly, heat to 60-80°C and keep stirring for 30-50 minutes, add 5-10 parts of polyvinyl alcohol, then heat to 85-90°C, stir at a speed of 3000-4000 r / min for 20-30 minutes to obtain a coating solution; The core material is put into a coating granulator, and the coating liquid is sprayed onto the core material. The rotation speed of the coating granulator is 15-20r / min, the temperature is 60-70°C, and the spraying speed is 15-18g / min. After the coating is completed, the obtained coated particles are dried by hot air until they are completely solidified, and then cooled at room temperature to obtain a composite expansion material.

10. A waterproof support structure for an underground tunnel, characterized in that: Prepared by the underground tunnel waterproof support method according to any one of claims 1 to 9, comprising a buffer layer and a support layer; The support layer is made of a first material, which includes the following components in parts by weight: 20-60 parts of cement, 10-15 parts of vitrified microspheres, 1-10 parts of waterproofing agent, 1-5 parts of composite expansion material, 20-40 parts of admixture, 0.5-1.5 parts of water reducing agent, 1-5 parts of early strength agent, 2-4 parts of thixotropic agent, 80-120 parts of high-strength aggregate, 3-6 parts of accelerating agent, 5-15 parts of modified polyvinyl alcohol fiber and 10-30 parts of water; The modified polyvinyl alcohol fiber preparation method comprises the following steps: The polyvinyl alcohol fiber is immersed in a sodium hydroxide solution, stirred for 1-3 hours, washed with water, immersed in anhydrous ethanol, immersed for 1-2 hours, and dried to obtain a modified fiber precursor; Ultrasonic dispersion of carbon nanotubes in ethanol, then adding the modified fiber precursor, stirring for 1-2 hours, and drying to obtain a modified fiber intermediate; The graphene oxide is dissolved in acetic acid, and then the modified fiber intermediate is added, stirred for 2-5 hours, and then dried to obtain the modified polyvinyl alcohol fiber; The weight ratio of the polyvinyl alcohol fiber, the carbon nanotube and the graphene oxide is 1:(0.5-0.8):(0.4-0.6).

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