A coal mine tunnel support protection structure and a preparation method and application thereof

Abstract

This invention provides a support and protection structure for coal mine roadways, its preparation method, and its application. Specifically, it uses high-strength, low-modulus iron-based amorphous alloy chopped fibers reinforced with polyurethane foam as the resin-based reinforcing material, combined with a steel mesh to form a metal-framed resin-based composite support and protection structure. This effectively solves the problem of fine sand and gravel falling, and significantly reduces weight compared to traditional cement-sprayed composite structures, thus improving the support and protection capabilities of coal mine roadways. Furthermore, the amorphous alloy fibers used are modified iron-based amorphous alloy chopped fibers with surface grafted dual active functional groups. After modification, the fiber surface becomes an active interface homologous to polyurethane, allowing for uniform dispersion in the system and avoiding problems such as agglomeration and sedimentation. The modified fibers also form chemical bonds and molecular entanglements with the matrix, resulting in a reinforcing and toughening effect. Simultaneously, the modified fibers optimize foaming and nucleation, forming a dense, high-closed-cell structure, improving waterproofing, corrosion resistance, durability, and enhancing the bonding and anchoring effect with the steel mesh.

Description

Technical Field

[0001] This invention belongs to the field of coal mine roadway support engineering technology, specifically relating to a coal mine roadway support and protection structure, its preparation method, and its application. Background Technology

[0002] After the excavation of underground roadways in coal mines, the surrounding rock is prone to loosening, collapse, and the falling of sand and gravel, seriously threatening the safety of underground workers and equipment. Therefore, it is necessary to provide support and protection for the roadways. Currently, the commonly used support and protection structure for coal mine roadways is a composite structure of steel mesh and cement spraying. First, the steel mesh is fixed to the surrounding rock of the roadway with anchor bolts, and then cement slurry is sprayed to fill the gaps in the mesh, thus supporting the roadway while preventing sand and gravel from falling.

[0003] However, this traditional composite structure faces many problems: First, the cement slurry has a large particle size, leaving gaps in the protection and making it difficult to completely fill the tiny mesh of the steel structure mesh, thus failing to effectively solve the problem of fine sand and small stones falling into the mesh; second, cement materials are prone to absorbing water, and in the humid underground environment, the steel structure mesh is easily exposed to moisture in the cement, causing electrochemical corrosion, reducing the strength and service life of the steel structure mesh, and seriously affecting the support and protection effect; in addition, the composite structure after cement spraying is heavy, placing a high additional load on the surrounding rock of the tunnel, and the cement curing time is long and the construction process is complicated, which is not conducive to rapid underground construction; finally, the cement layer is also prone to cracking and peeling, resulting in high maintenance costs in the later stage.

[0004] With the rapid development of polymer materials, polyether-type rigid polyurethane foam is gradually replacing traditional spraying due to its advantages such as good adhesion, convenient foaming and molding, and closed-cell waterproofing. However, pure rigid polyurethane foam has problems such as low strength, poor impact resistance, and susceptibility to irreversible cracks due to surrounding rock deformation during long-term service, making it difficult to meet the long-term support requirements of deep tunnels. To improve the mechanical properties of rigid polyurethane foam, existing technologies have attempted to use inorganic fibers such as glass fiber and carbon fiber for reinforcement. However, these common fibers have poor interfacial compatibility with the polyurethane matrix and are prone to agglomeration and sedimentation in the foamed polyurethane raw materials. This not only fails to fully exert the fiber reinforcement effect but also clogs high-pressure spraying equipment, making it unsuitable for continuous underground construction.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a support and protection structure for coal mine roadways, its preparation method, and its application. This invention effectively solves the problems of traditional structures being unable to prevent the falling of fine sand and gravel, the easy corrosion of steel mesh, and the large overall weight, thereby improving the support and protection capabilities of roadways. At the same time, it provides a preparation method for this structure, which is simple, efficient, and suitable for on-site construction in coal mines.

[0007] To achieve the above objectives, the present invention provides a support and protection structure for coal mine roadways. The protection structure is a metal skeleton resin-based composite structure, which is formed by a steel structure mesh and amorphous alloy fiber reinforced foamed polyurethane.

[0008] The steel structure mesh is fixed to the inner wall of the surrounding rock of the coal mine roadway by anchor bolts and anchor cables;

[0009] The amorphous alloy fiber-reinforced foamed polyurethane is sprayed and coated on the surface and mesh gaps of the steel structure mesh, and is tightly bonded to the inner wall of the surrounding rock of the tunnel.

[0010] The amorphous alloy fibers are high-strength and low-modulus, and are uniformly dispersed in the foamed polyurethane matrix.

[0011] In this technical solution, amorphous alloy fibers have the characteristics of high strength, high toughness and corrosion resistance, while foamed polyurethane has the advantages of being lightweight, having good adhesion and fast molding. Combining amorphous alloy fibers and foamed polyurethane and then compositing them with steel structure mesh can effectively make up for the shortcomings of traditional cement spraying composite structures, becoming a new technical direction for support and protection of coal mine roadways.

[0012] In a preferred embodiment, the steel structure mesh is a galvanized steel mesh or a high-manganese steel mesh, with a mesh size of 5~20mm, a wire diameter of 2~5mm, and a square or diamond-shaped mesh structure.

[0013] In a preferred embodiment, the anchor bolt is a metal anchor bolt, which is laid along the grid intersections and edges of the steel structure mesh. The anchor cable is adapted to connect with the metal anchor bolt, pressing and fixing the steel structure mesh to the tunnel ceiling and the inner wall of the surrounding rock. The spacing between adjacent metal anchor bolts is 0.5~1.5 m.

[0014] In a preferred embodiment, the anchor cable is a low-relaxation prestressed steel strand anchor cable with a diameter of 15~18 mm, a length of 4~8 m, and a spacing of 2000 mm×2000 mm~3000 mm×3000 mm, used for reinforcement and anchoring in high-stress roadways.

[0015] In a preferred embodiment, the amorphous alloy fiber is a short-cut iron-based amorphous alloy fiber with a single filament diameter of 0.1~0.5 mm, a length of 5~20 mm, a tensile strength ≥1500 MPa, and an elastic modulus ≤120 GPa. The mass content of the amorphous alloy fiber in the foamed polyurethane matrix is ​​3~6%. In this invention, limiting the above-mentioned amorphous alloy fiber parameter range ensures both the reinforcing and toughening effect of the fiber and avoids poor atomization caused by excessively thick and long fibers. Simultaneously, limiting the above-mentioned amorphous alloy fiber content is used to construct the three-dimensional fiber network; if it is below 3%, the reinforcing effect is insufficient; if it is above 6%, fiber agglomeration is likely to occur, affecting the polyurethane foam molding.

[0016] In a preferred embodiment, the amorphous alloy fiber reinforced polyurethane foam has a foaming ratio of 3.5 to 4.5 times, an apparent density of 250 to 330 kg / m³ after curing, a bonding strength with the steel structure mesh of ≥1.2 MPa, a closed-cell rate of ≥72%, a compressive strength of ≥18 MPa, and a flexural strength of ≥7 MPa.

[0017] In a preferred embodiment, the amorphous alloy fiber is a modified iron-based amorphous alloy chopped fiber with surface grafted dual active functional groups. The specific modification method includes the following steps:

[0018] Preparation of hydroxylated amorphous fibers: Iron-based amorphous alloy short-cut fibers are ultrasonically cleaned with anhydrous ethanol to remove surface oil and oxide layer. After draining, they are soaked in hydrogen peroxide solution with a mass concentration of 3-5% and stirred at room temperature for a period of time to complete surface hydroxylation modification. After removal, they are washed with deionized water until neutral and dried to obtain hydroxylated amorphous fibers.

[0019] Preparation of modified reaction solution: Dithiodibenzoic acid, polyoxyethylene diamine, dibutyltin dilaurate and dimethylformamide are mixed in a mass ratio of (15~25):(30~50):(0.5~1):(800~1200) and stirred until completely dissolved to obtain modified reaction solution;

[0020] Dual-functional group grafting modification: The prepared hydroxylated amorphous fiber and the modification reaction solution are mixed, stirred evenly, heated to 75~85 ℃, and reacted in a sealed environment at a constant temperature for 3.5~4.5 hours. After the reaction is completed, the fiber is taken out, washed with anhydrous ethanol and dried to obtain modified amorphous alloy fiber.

[0021] In this technical solution, by performing hydroxylation pretreatment and dual-active functional group grafting modification on the iron-based amorphous alloy fibers with the aforementioned specifications, the problems of uneven dispersion and weak interfacial bonding of amorphous alloy fibers in foamed polyurethane raw materials are further solved. At the same time, the modified fibers can form stable chemical bonds and molecular chain entanglements with the polyurethane matrix, thereby improving the reinforcement and toughening effect of the polyurethane matrix. Combined with a steel mesh skeleton and metal anchor system, an integrated protective structure with high strength, high closed-cell rate, and resistance to mine water corrosion can be constructed.

[0022] Preferably, in the step of preparing hydroxylated amorphous fibers, the ultrasonic cleaning time with anhydrous ethanol is 10-15 minutes;

[0023] Preferably, in the step of preparing hydroxylated amorphous fibers, the mass ratio of the iron-based amorphous alloy chopped fibers to the hydrogen peroxide solution is 1:(3~5).

[0024] Preferably, in the step of preparing hydroxylated amorphous fibers, the stirring time at room temperature is 2 to 3 hours;

[0025] Preferably, in the step of preparing hydroxylated amorphous fibers, the drying method can be a conventional method known to those skilled in the art, such as drying at 60-80°C for 2-4 hours;

[0026] Preferably, in the step of preparing the modified reaction solution, the number average molecular weight of the polyoxyethylene diamine is 1000~4000;

[0027] Preferably, in the step of preparing the modified reaction solution, the ratio of the reaction solution is: the mass ratio of dithiobenzoic acid (CAS Registry No. 119-80-2), polyoxyethylene diamine (CAS Registry No. 24991-53-5), dibutyltin dilaurate (CAS Registry No. 77-58-7), and dimethylformamide (DMF) = (18~22):(35~45):(0.6~0.8):(900~1100); in the modified reaction solution, dithiobenzoic acid provides reversible disulfide bond active sites, polyoxyethylene diamine provides hydrogen bond active sites and improves compatibility with polyether polyurethane, dibutyltin dilaurate catalyzes the esterification and amidation reactions efficiently, and dimethylformamide ensures that all components are fully dissolved, providing a uniform and stable reaction system for the grafting reaction and avoiding uneven local reactions;

[0028] Preferably, in the dual-functional group grafting modification step, the mass ratio of the hydroxylated amorphous fiber to the modification reaction solution is 1:(9~12). In this step, if the amount of modification reaction solution is insufficient, the amorphous alloy fiber cannot be completely immersed, the viscosity of the reaction system is too high, and the solute is unevenly dispersed, resulting in insufficient grafting reaction on the fiber surface and affecting the modification effect. If the amount of modification reaction solution is excessive, it will waste solvent, make the solute concentration in the reaction system too low, reduce the grafting reaction efficiency, and significantly increase the workload of subsequent solvent recovery, fiber cleaning, etc.

[0029] Preferably, in the dual-functional group grafting modification step, the anhydrous ethanol washing is performed 2 to 3 times, each time for 3 to 7 minutes; the drying method can be a conventional method known to those skilled in the art, such as drying at 60-80°C for 2 to 4 hours.

[0030] Preferably, the modified amorphous alloy fiber reinforced polyurethane foam has a foaming ratio of 3.8 to 4.8 times, an apparent density of 235 to 310 kg / m³ after curing, a bonding strength with the steel structure mesh of ≥2.3 MPa, a closed-cell rate of ≥92%, a compressive strength of ≥23 MPa, and a flexural strength of ≥10 MPa.

[0031] This invention also provides a method for preparing any of the above-mentioned coal mine roadway support and protection structures, comprising the following steps:

[0032] (1) Roadway pretreatment: Clean the rock surface of the roof of the coal mine roadway, remove loose stones, slag and loose rock layers, and ensure that the rock surface is flat and dry;

[0033] (2) Fixing the steel structure mesh: Lay the steel structure mesh on the treated roadway roof rock surface, adjust the position of the mesh to fit the rock surface, drill holes at the preset position and insert anchor bolts, and press and fix the steel structure mesh to the rock surface with anchor cables to ensure that the mesh is not loose or wrinkled;

[0034] (3) Preparation of amorphous alloy fiber reinforced polyurethane foam: Add iron-based amorphous alloy short chopped fibers or modified iron-based amorphous alloy short chopped fibers to polyurethane foam raw material A, stir at high speed to make the fibers uniformly dispersed, and obtain fiber modified material.

[0035] (4) Spraying and coating: The fiber modified material and the foamed polyurethane raw material B are mixed by high pressure spraying equipment and sprayed onto the surface of the fixed steel structure mesh and the mesh gaps, so that the polyurethane foams during the spraying process and is tightly bonded to the steel structure mesh and the tunnel rock surface.

[0036] (5) Curing and molding: The sprayed amorphous alloy fiber reinforced polyurethane foam cures naturally in the underground environment to form a metal skeleton resin-based composite support and protection structure, thus completing the support and protection construction of the coal mine roadway.

[0037] Preferably, in step (3), the high-speed stirring speed is 800~1500 r / min and the stirring time is 3~8 minutes.

[0038] Preferably, in step (4), the spraying pressure of the high-pressure spraying equipment is 10~15 MPa, the spraying distance is 30~50 cm, the spraying moving speed is 0.2~0.5 m / s, and the spraying thickness is 10~30 mm.

[0039] Preferably, in step (5), the natural curing time is 4 to 8 hours.

[0040] The present invention also provides the application of any of the above-mentioned coal mine roadway support and protection structures in coal mine roadway surrounding rock support, roadway roof and sidewall protection, and deformation control of high ground stress mining roadways.

[0041] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0042] 1. The protective structure of this invention is a metal-framed resin-based composite structure. Amorphous alloy fiber-reinforced polyurethane foam completely fills the mesh gaps of the steel mesh, effectively blocking fine sand and small stones smaller than the mesh size from falling. This solves the protective loophole problem of traditional cement-coated structures and improves the safety of the tunnel. Simultaneously, because the polyurethane foam layer completely covers the surface of the steel mesh, it isolates the steel mesh from contact with humid air and water underground, achieving comprehensive corrosion protection for the steel mesh, significantly extending its service life, and ensuring the long-term stability of the supporting structure.

[0043] 2. This invention uniformly disperses high-strength, low-modulus amorphous alloy fibers within a foamed polyurethane matrix, effectively enhancing the tensile, flexural strength, and toughness of the polyurethane layer. Combined with a steel mesh metal skeleton for support, this forms a rigid-flexible composite structure, significantly improving overall support and protection capabilities, and making it suitable for the complex stress environment of surrounding rock in underground coal mines. Compared to traditional cement materials, the amorphous alloy fibers used in this invention have lower density and lighter weight, reducing the additional load on the surrounding rock of the roadway and preventing further loosening of the surrounding rock due to excessive load. Simultaneously, the lightweight structure facilitates underground construction and transportation.

[0044] 3. This invention further provides a modification scheme for amorphous alloy fibers. After hydroxylation pretreatment and dual-functional group grafting modification, the surface of the amorphous fibers changes from an inorganic inert state to an active organic interface homologous to the polyurethane matrix, achieving uniform dispersion in the foamed polyurethane raw material without agglomeration or sedimentation. Secondly, the modified fibers can form stable chemical bonds and molecular chain entanglements with the polyurethane matrix, completely eliminating interface defects and stress concentration between the fibers and the matrix, achieving further reinforcement and toughening of the polyurethane matrix. In addition, the uniformly dispersed modified fibers can also serve as cell nucleation sites, promoting uniform and stable cell growth and avoiding defects such as cell collapse and shrinkage. The resulting cell structure is dense and complete with a high closed-cell rate, effectively blocking the penetration of corrosive media and improving the waterproof, corrosion-resistant, and long-term service durability of the protective structure. Finally, the modified polyurethane composite system significantly improves the wettability and mechanical anchoring ability of the steel structure mesh, forming a stronger integrated bond with the steel mesh, further avoiding problems such as debonding, hollowing, and detachment.

[0045] 4. The preparation method of the present invention is simple, the spraying construction speed is fast, and the polyurethane foam curing time is short. Compared with the traditional cement spraying, the construction efficiency is increased by 3 to 5 times, which is suitable for rapid support construction in coal mines. Moreover, the construction process does not require large heavy equipment, the operation is convenient, and it is highly adaptable to the underground construction environment. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] This invention provides a coal mine roadway support and protection structure, its preparation method, and its application, solving problems in the prior art such as the inability of traditional coal mine roadway protection structures to prevent the falling of fine sand and gravel, easy corrosion of steel structure mesh, and large overall weight.

[0048] The technical solution of this application will be described in detail below through specific embodiments:

[0049] Unless otherwise specified, the technical means used in this invention are conventional means well known to those skilled in the art. All raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. Unless otherwise specified, all reagents used in this invention are of analytical grade. In the embodiments of this invention, component A of the polyurethane foam is WANEFOAM® 9260, and component B is the curing agent WANNATE® 2208, with a volume ratio of component A to component B of 1:1.

[0050] Example 1

[0051] A coal mine roadway support and protection structure is formed by a composite of steel mesh and amorphous alloy fiber reinforced polyurethane foam. The steel mesh is a high-manganese steel mesh with a mesh size of 10mm, a wire diameter of 3mm, and a square grid. The anchor bolts are metal anchor bolts with a spacing of 1.0m, and the anchor cables are low-relaxation prestressed steel strand anchor cables with a diameter of 15.24mm, a length of 4m, and a spacing of 2000mm×2000mm, which fix the steel mesh to the roadway ceiling. The amorphous alloy fiber is a high-strength, low-modulus iron-based amorphous alloy chopped fiber with a diameter of 0.2mm, a length of 10mm, a tensile strength of 1600MPa, an elastic modulus of 70GPa, and a mass content of 5% in the polyurethane foam.

[0052] The preparation method of the above structure includes the following steps:

[0053] (1) Roadway pretreatment: Clean the rock surface of the roof of the coal mine roadway, remove loose stones, slag and loose rock layers, and ensure that the rock surface is flat and dry;

[0054] (2) Steel structure mesh fixing: Lay high manganese steel mesh and attach it to the rock surface, drill holes at 1.0m intervals, insert metal anchor rods, and fix the mesh body by anchor cables to ensure that the mesh body is not loose or wrinkled;

[0055] (3) Preparation of amorphous alloy fiber reinforced polyurethane foam: The above-mentioned amorphous alloy fiber was added to polyether-type rigid polyurethane foam A, and stirred at 1000 r / min for 5 min to make the fiber uniformly dispersed, so as to obtain fiber modified material; the mass of amorphous alloy fiber was 5% of the total mass of A and B materials;

[0056] (4) Spraying composite: The fiber modified material (material A + amorphous alloy fiber) and material B are sprayed onto the surface of the steel structure mesh at a pressure of 10MPa, a spraying distance of 40cm and a moving speed of 0.3m / s. The thickness of a single spray is controlled at 10 mm, and the total thickness is 20 mm after two sprays. The edges of the mesh and the anchor rod / anchor cable nodes are sprayed in a focused manner.

[0057] (5) Curing and molding: The sprayed amorphous alloy fiber reinforced polyurethane foam is naturally cured in the underground environment for 5 hours to form a metal skeleton resin-based composite support and protection structure, thus completing the coal mine roadway support and protection construction.

[0058] The performance of the prepared coal mine roadway support and protection structure was tested, and the results were as follows: the foaming ratio of amorphous alloy fiber reinforced polyurethane foam was 4 times, the apparent density after curing was 287.5 kg / m³, the bonding strength with the steel structure mesh was 1.5 MPa, the closed-cell rate (GB / T 10799-2008) was 77%, the compressive strength (GB / T 8813-2020) was 22 MPa, and the flexural strength (GB / T9341-2008) was 8.5 MPa.

[0059] Example 2

[0060] A coal mine roadway support and protection structure is formed by a composite of steel mesh and amorphous alloy fiber reinforced polyurethane foam. The steel mesh is galvanized steel mesh with a mesh size of 5mm, a wire diameter of 2mm, and a diamond-shaped grid. The anchor bolts are metal anchor bolts with a spacing of 0.8m, and the anchor cables are low-relaxation prestressed steel strand anchor cables with a diameter of 15.24mm, a length of 4m, and a spacing of 2000mm×2000mm, which fix the steel mesh to the roadway ceiling. The amorphous alloy fiber is a high-strength, low-modulus iron-based amorphous alloy chopped fiber with a diameter of 0.1mm, a length of 5mm, a tensile strength of 1500MPa, an elastic modulus of 60GPa, and a mass content of 3% in the polyurethane foam.

[0061] The preparation method of the above structure includes the following steps:

[0062] (1) Roadway pretreatment: Clean the rock surface of the roof of the coal mine roadway, remove loose stones, slag and loose rock layers, and ensure that the rock surface is flat and dry;

[0063] (2) Fixing the steel structure mesh: Lay galvanized steel mesh and attach it to the rock surface, drill holes at 0.8m intervals, insert metal anchor rods, and fix the mesh body by pressing it with anchor cables to ensure that the mesh body is not loose or wrinkled;

[0064] (3) Preparation of amorphous alloy fiber reinforced polyurethane foam: The above-mentioned amorphous alloy fiber was added to polyether-type rigid polyurethane foam A material and stirred at 1000 r / min for 3 min to make the fiber uniformly dispersed, thus obtaining the fiber modified material; the mass of amorphous alloy fiber was 3% of the total mass of A material and B material;

[0065] (4) Spraying composite: The fiber modified material (material A + amorphous alloy fiber) and material B are sprayed onto the surface of the steel structure mesh at a pressure of 12MPa, a spraying distance of 30cm and a moving speed of 0.2m / s. The spraying thickness is controlled at 10mm. The edges of the mesh and the anchor rod / anchor cable nodes are sprayed in a focused manner.

[0066] (5) Curing and molding: The sprayed amorphous alloy fiber reinforced polyurethane foam is naturally cured in the underground environment for 4 hours to form a metal skeleton resin-based composite support and protection structure, thus completing the coal mine roadway support and protection construction.

[0067] The performance of the prepared coal mine roadway support and protection structure was tested, and the results were as follows: the foaming ratio of amorphous alloy fiber reinforced polyurethane foam was 4.5 times, the apparent density after curing was 255.6 kg / m³, the bonding strength with the steel structure mesh was 1.2 MPa, the closed-cell rate was 72%, the compressive strength was 18 MPa, and the flexural strength was 7.2 MPa.

[0068] Example 3

[0069] A coal mine roadway support and protection structure is formed by a composite of steel mesh and amorphous alloy fiber reinforced polyurethane foam. The steel mesh is a high-manganese steel mesh with a mesh size of 20mm, a wire diameter of 5mm, and a square grid. The anchor bolts are metal anchor bolts with a spacing of 1.2m, and the anchor cables are low-relaxation prestressed steel strand anchor cables with a diameter of 15.24mm, a length of 4m, and a spacing of 2000mm×2000mm, which fix the steel mesh to the roadway ceiling. The amorphous alloy fiber is a high-strength, low-modulus iron-based amorphous alloy chopped fiber with a diameter of 0.3mm, a length of 15mm, a tensile strength of 2000MPa, an elastic modulus of 80GPa, and a mass content of 6% in the polyurethane foam.

[0070] The preparation method of the above structure includes the following steps:

[0071] (1) Roadway pretreatment: Clean the rock surface of the roof of the coal mine roadway, remove loose stones, slag and loose rock layers, and ensure that the rock surface is flat and dry;

[0072] (2) Steel structure mesh fixing: Lay high manganese steel mesh and attach it to the rock surface, drill holes at 1.2m intervals, insert metal anchor rods, and fix the mesh body by anchor cables to ensure that the mesh body is not loose or wrinkled;

[0073] (3) Preparation of amorphous alloy fiber reinforced polyurethane foam: The above-mentioned amorphous alloy fiber was added to polyether type polyurethane rigid foam A, and stirred at 1200 r / min for 8 min to make the fiber uniformly dispersed, so as to obtain fiber modified material; the mass of amorphous alloy fiber was 6% of the total mass of A and B materials;

[0074] (4) Spraying composite: The fiber modified material (material A + amorphous alloy fiber) and material B are sprayed onto the surface of the steel structure mesh at a pressure of 15MPa, a spraying distance of 50cm and a moving speed of 0.5m / s. The thickness of a single spray is controlled at 15 mm, and the total thickness is 30 mm after two sprays. The edges of the mesh and the anchor rod / anchor cable nodes are sprayed in a focused manner.

[0075] (5) Curing and molding: The sprayed amorphous alloy fiber reinforced foamed polyurethane is naturally cured in the underground environment for 6 hours to form a metal skeleton resin-based composite support and protection structure, thus completing the coal mine roadway support and protection construction.

[0076] The performance of the prepared coal mine roadway support and protection structure was tested, and the results were as follows: the foaming ratio of amorphous alloy fiber reinforced polyurethane foam was 3.5 times, the apparent density was 328.6 kg / m³, the bonding strength was 1.8 MPa, the closed-cell rate was 75%, the compressive strength was 28 MPa, and the flexural strength was 10.5 MPa.

[0077] Example 4

[0078] The only difference from Example 1 is that the amorphous alloy fiber used is a modified iron-based amorphous alloy short fiber with surface grafted dual active functional groups; the other dosages and processes are exactly the same as in Example 1.

[0079] The modified iron-based amorphous alloy short fibers with surface-grafted dual active functional groups were prepared by the following method:

[0080] Preparation of hydroxylated amorphous fibers: The iron-based amorphous alloy short-cut fibers used in Example 1 were ultrasonically cleaned with anhydrous ethanol for 10 minutes, drained, and then immersed in a 4% hydrogen peroxide solution at a mass ratio of 1:4. The mixture was stirred at room temperature for 3 hours to complete the surface hydroxylation modification. After removal, the fibers were washed with deionized water until neutral and dried at 60°C for 2 hours to obtain hydroxylated amorphous fibers.

[0081] Preparation of modified reaction solution: Dithiodibenzoic acid, polyoxyethylene diamine (number average molecular weight of 2000), dibutyltin dilaurate and dimethylformamide are mixed in a mass ratio of 20:40:0.7:1000 and stirred until completely dissolved to obtain the modified reaction solution;

[0082] Dual-functional group grafting modification: The prepared hydroxylated amorphous fiber and the modification reaction solution were mixed at a mass ratio of 1:10, stirred evenly, heated to 80℃, and reacted in a sealed environment at a constant temperature for 4 hours. After the reaction was completed, the fiber was taken out, washed with anhydrous ethanol and dried to obtain modified amorphous alloy fiber.

[0083] The performance of the prepared coal mine roadway support and protection structure was tested, and the results were as follows: the expansion ratio of the modified amorphous alloy fiber reinforced polyurethane foam was 4.2 times, the apparent density after curing was 273.8 kg / m³, the bonding strength with the steel structure mesh was 2.9 MPa, the closed-cell rate was 93%, the compressive strength was 28.5 MPa, and the flexural strength was 12.2 MPa.

[0084] Example 5

[0085] The only difference from Example 2 is that the amorphous alloy fiber used is a modified iron-based amorphous alloy short fiber with surface grafted dual active functional groups; the other dosages and processes are exactly the same as in Example 2.

[0086] The modified iron-based amorphous alloy short fibers with surface-grafted dual active functional groups were prepared by the following method:

[0087] Preparation of hydroxylated amorphous fibers: The iron-based amorphous alloy short-cut fibers used in Example 2 were ultrasonically cleaned with anhydrous ethanol for 10 minutes, drained, and then immersed in a 3% hydrogen peroxide solution at a mass ratio of 1:3. The surface was stirred at room temperature for 2 hours to complete the surface hydroxylation modification. After removal, the fibers were washed with deionized water until neutral and dried at 60°C for 2 hours to obtain hydroxylated amorphous fibers.

[0088] Preparation of modified reaction solution: Dithiodibenzoic acid, polyoxyethylene diamine (number average molecular weight of 2000), dibutyltin dilaurate and dimethylformamide are mixed in a mass ratio of 18:35:0.6:900 and stirred until completely dissolved to obtain the modified reaction solution;

[0089] Dual-functional group grafting modification: The prepared hydroxylated amorphous fiber and the modification reaction solution were mixed at a mass ratio of 1:9, stirred evenly, heated to 75℃, and reacted in a sealed environment at a constant temperature for 3.5 hours. After the reaction was completed, the fiber was taken out, washed with anhydrous ethanol and dried to obtain modified amorphous alloy fiber.

[0090] The performance of the prepared coal mine roadway support and protection structure was tested, and the results were as follows: the expansion ratio of the modified amorphous alloy fiber reinforced polyurethane foam was 4.8 times, the apparent density after curing was 239.6 kg / m³, the bonding strength with the steel structure mesh was 2.3 MPa, the closed-cell rate was 92%, the compressive strength was 23.8 MPa, and the flexural strength was 10.1 MPa.

[0091] Example 6

[0092] The only difference from Example 3 is that the amorphous alloy fiber used is a modified iron-based amorphous alloy short fiber with surface grafted dual active functional groups; the other dosages and processes are exactly the same as in Example 3.

[0093] The modified iron-based amorphous alloy short fibers with surface-grafted dual active functional groups were prepared by the following method:

[0094] Preparation of hydroxylated amorphous fibers: The iron-based amorphous alloy short-cut fibers used in Example 3 were ultrasonically cleaned with anhydrous ethanol for 10 minutes, drained, and then immersed in a 5% hydrogen peroxide solution at a mass ratio of 1:5. The surface was stirred at room temperature for 3 hours to complete the surface hydroxylation modification. After removal, the fibers were washed with deionized water until neutral and dried at 60°C for 2 hours to obtain hydroxylated amorphous fibers.

[0095] Preparation of modified reaction solution: Dithiodibenzoic acid, polyoxyethylene diamine (number average molecular weight of 4000), dibutyltin dilaurate and dimethylformamide are mixed in a mass ratio of 22:45:0.8:1100 and stirred until completely dissolved to obtain the modified reaction solution;

[0096] Dual-functional group grafting modification: The prepared hydroxylated amorphous fiber and the modification reaction solution were mixed at a mass ratio of 1:12, stirred evenly, heated to 85℃, and reacted in a sealed environment at a constant temperature for 4.5 hours. After the reaction was completed, the fiber was taken out, washed with anhydrous ethanol and dried to obtain modified amorphous alloy fiber.

[0097] The performance of the prepared coal mine roadway support and protection structure was tested, and the results were as follows: the expansion ratio of the modified amorphous alloy fiber reinforced polyurethane foam was 3.8 times, the apparent density after curing was 302.6 kg / m³, the bonding strength with the steel structure mesh was 3.4 MPa, the closed-cell rate was 95%, the compressive strength was 35.2 MPa, and the flexural strength was 14.8 MPa.

[0098] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A support and protection structure for coal mine roadways, characterized in that, The protective structure is a metal skeleton resin-based composite structure, which is formed by steel structure mesh and amorphous alloy fiber reinforced foamed polyurethane. The steel structure mesh is fixed to the inner wall of the surrounding rock of the coal mine roadway by anchor bolts and anchor cables; The amorphous alloy fiber-reinforced foamed polyurethane is sprayed and coated on the surface and mesh gaps of the steel structure mesh, and is tightly bonded to the inner wall of the surrounding rock of the tunnel. The amorphous alloy fibers are high-strength and low-modulus, and are uniformly dispersed in the foamed polyurethane matrix.

2. The coal mine roadway support and protection structure as described in claim 1, characterized in that, The steel structure mesh is galvanized steel mesh or high manganese steel mesh, with a mesh size of 5~20 mm, a wire diameter of 2~5 mm, and a square or diamond mesh structure.

3. The coal mine roadway support and protection structure as described in claim 1, characterized in that, The anchor bolts are metal anchor bolts, which are laid along the grid intersections and edges of the steel structure mesh. The anchor cables are adapted to connect with the metal anchor bolts, pressing and fixing the steel structure mesh to the tunnel ceiling and the inner wall of the surrounding rock. The spacing between adjacent metal anchor bolts is 0.5~1.5m.

4. The coal mine roadway support and protection structure as described in claim 1, characterized in that, The amorphous alloy fiber is an iron-based amorphous alloy chopped fiber with a single filament diameter of 0.1~0.5 mm, a length of 5~20 mm, a tensile strength ≥1500 MPa, and an elastic modulus ≤120 GPa. The mass content of the amorphous alloy fiber in the foamed polyurethane matrix is ​​3~6%.

5. The coal mine roadway support and protection structure as described in claim 4, characterized in that, The amorphous alloy fiber is a modified iron-based amorphous alloy short-cut fiber with surface grafted dual active functional groups. The specific modification method includes the following steps: Preparation of hydroxylated amorphous fibers: Iron-based amorphous alloy short-cut fibers are ultrasonically cleaned with anhydrous ethanol to remove surface oil and oxide layer. After draining, they are soaked in hydrogen peroxide solution with a mass concentration of 3-5% and stirred at room temperature for a period of time to complete surface hydroxylation modification. After removal, they are washed with deionized water until neutral and dried to obtain hydroxylated amorphous fibers. Preparation of modified reaction solution: Dithiodibenzoic acid, polyoxyethylene diamine, dibutyltin dilaurate and dimethylformamide are mixed in a mass ratio of (15~25):(30~50):(0.5~1):(800~1200) and stirred until completely dissolved to obtain modified reaction solution; Dual-functional group grafting modification: The prepared hydroxylated amorphous fiber and the modification reaction solution are mixed, stirred evenly, heated to 75~85 ℃, and reacted in a sealed environment at a constant temperature for 3.5~4.5 hours. After the reaction is completed, the fiber is taken out, washed with anhydrous ethanol and dried to obtain modified amorphous alloy fiber.

6. The coal mine roadway support and protection structure as described in claim 5, characterized in that, In the dual-functional group grafting modification step, the mass ratio of the hydroxylated amorphous fiber to the modified reaction solution is 1:(9~12).

7. The method for preparing the coal mine roadway support and protection structure according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Roadway pretreatment: Clean the rock surface of the roof of the coal mine roadway, remove loose stones, slag and loose rock layers, and ensure that the rock surface is flat and dry; (2) Fixing the steel structure mesh: Lay the steel structure mesh on the treated roadway roof rock surface, adjust the position of the mesh to fit the rock surface, drill holes at the preset position and insert anchor bolts, and press and fix the steel structure mesh to the rock surface with anchor cables to ensure that the mesh is not loose or wrinkled; (3) Preparation of amorphous alloy fiber reinforced polyurethane foam: Add iron-based amorphous alloy short fiber or modified iron-based amorphous alloy short fiber to material A of polyurethane foam, stir at high speed to make the fiber uniformly dispersed, and obtain fiber modified material. (4) Spraying and coating: The fiber modified material and the foamed polyurethane raw material B are mixed by high pressure spraying equipment and sprayed onto the surface of the fixed steel structure mesh and the mesh gaps, so that the polyurethane foams during the spraying process and is tightly bonded to the steel structure mesh and the tunnel rock surface. (5) Curing and molding: The sprayed amorphous alloy fiber reinforced polyurethane foam cures naturally in the underground environment to form a metal skeleton resin-based composite support and protection structure, thus completing the support and protection construction of the coal mine roadway.

8. The method for preparing the coal mine roadway support and protection structure as described in claim 7, characterized in that, In step (4), the spraying pressure of the high-pressure spraying equipment is 10~15 MPa, the spraying distance is 30~50 cm, the spraying moving speed is 0.2~0.5 m / s, and the spraying thickness is 10~30 mm.

9. The application of the coal mine roadway support and protection structure as described in any one of claims 1-6 in the support of surrounding rock, protection of roadway roof and sidewalls, and deformation control of high ground stress mining roadways.