Construction methods, structures and construction systems for sidewall protection in coal seam roadways

Abstract

This invention discloses a construction method, structure, and system for sidewall protection in coal mine roadways, relating to the field of coal mine roadway support and disaster prevention. Addressing the core pain points of existing support technologies—such as the large deformation of sidewalls and high risk of gas outbursts in deep, high-stress, soft, and outburst-prone coal seams, the disconnect between internal and external sealing, the brittle fracture of rigid components, and the easy peeling of surface coatings—this invention adopts a three-in-one fully flexible composite wall protection scheme: deep, root-like flexible chains are formed through high-pressure grouting via drilling; flexible rivet head anchoring nodes are constructed integrally with the deep chains, utilizing the properties of the grouting material before initial setting; and a thin TSL spray coating on the surface achieves a dual coupling of chemical cross-linking and physical encapsulation with the anchoring nodes, forming a fully tough wall protection system without rigid components. This system can simultaneously achieve coordinated control of large deformation of the roadway sidewalls and efficient gas sealing, and is suitable for sidewall support and disaster prevention in deep mine rock face exposure and soft, outburst-prone coal seam roadway excavation.

Description

Technical Field

[0001] This invention belongs to the field of coal mining and relates to coal mine roadway support and disaster prevention technology. In particular, it relates to a non-rigid component, deep-surface integrated collaborative wall protection construction method, structure and construction system for roadway sidewalls in deep, high-stress, soft, and outburst-protruding coal seams (coal firmness coefficient f<0.5). Background Technology

[0002] As coal mining depths increase year by year, deep mines generally face complex conditions such as high ground stress, high gas content, and soft, low-strength coal seams. During coal uncovering and tunneling, large deformation and expansion of the coal seam on the sidewalls, surface spalling, abnormal gas outbursts, and even coal and gas outbursts occur frequently. However, the inventors have discovered that existing roadway sidewall reinforcement technologies all have insurmountable limitations, as follows: (i) Internal grouting reinforcement has support blind spots: Although the existing flexible grouting technology can penetrate deep into the coal seam to form a "root-like" solidified body and improve the internal compressive and shear strength of the coal body, the roadway surface lacks effective circumferential tension constraints and tie anchoring. The surface broken coal is easily affected by weathering and mining dynamic pressure and will peel off, which will induce the gradual shear failure of the deep coal body and ultimately lead to the overall failure of the support system.

[0003] (ii) Thin Spray-on Liner (TSL) is prone to overall peeling and failure: Pure surface TSL support can only achieve surface sealing and lacks a strong bond with the deep coal seam. Under the action of large deformation of the surrounding rock and gas pressure, the TSL reinforcement coating is very prone to bulging, overall peeling or even tearing, and cannot achieve long-term stable support and sealing effect.

[0004] (III) There is an inherent mechanical mismatch between rigid and flexible materials: Existing "grouting / spraying + anchor cable" collaborative support schemes all use rigid metal anchor bolts / cables and trays as core anchoring force transmission components. In the environment of soft coal seams with ultra-large deformation, the ultimate deformation of rigid metal components is far lower than that of coal and flexible materials, which cannot adapt to the large deformation pressure relief requirements. They are very likely to become "brittle fracture points" of stress concentration, resulting in the industry-wide problem of anchor bolts breaking in rows and becoming detached.

[0005] (iv) The internal solidification and external sealing systems are disconnected, and there are leakage channels in the gas sealing: In the existing technology, deep grouting reinforcement and surface sealing are always two independent processes. The two are simply bonded together, and there are still microscopic interface penetration gaps. It is impossible to form a continuous gas sealing shell, and the risk of gas leakage along the orifice and interface always exists.

[0006] In summary, there is an urgent need in this field to propose a sidewall stability protection technology for coal seam roadways to overcome the problems existing in the above-mentioned technologies. Summary of the Invention

[0007] The purpose of this invention is to provide a novel construction method, structure, and system for sidewall support in coal seams. This system not only eliminates rigid metal anchoring components but also seamlessly couples the deep grouting consolidation body with the surface thin spray layer through physical and chemical means. It can simultaneously achieve coordinated control of large deformations in the sidewalls and efficient gas sealing, resulting in high construction efficiency and good safety performance. It is suitable for sidewall support and disaster prevention in deep mine rock tunnels and soft, outburst-prone coal seams, thus solving the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides the following solution: On the one hand, the present invention provides a method for constructing sidewall protection in coal seam roadways, comprising the following steps: S1. After drilling holes for the construction of the coal face to be reinforced in the roadway, seal the holes and insert an injection pipe. The injection pipe is exposed on the surface of the coal face and a set length is reserved. S2. Grout is injected into the borehole through the injection pipe so that the injected grout penetrates into the coal body fissures and undergoes a cross-linking and solidification reaction with the grout in the borehole, forming root-like flexible chains that are embedded in the coal body in the deep part of the coal seam. S3. During the node construction window period after grouting is completed, keep the injection pipe opening open so that the residual grout in the borehole can naturally extend around the injection pipe head and on the surface coal wall, and construct a flexible rivet head anchoring node at the borehole opening that is integrated with the grout in the borehole. S4. During the period when the active groups on the surface of the flexible rivet head anchoring node are not completely deactivated, a polymer thin-film coating material is uniformly sprayed on the coal wall surface and the surface of the flexible rivet head anchoring node to form a TSL reinforcement coating on the coal wall surface. The TSL reinforcement coating, the flexible rivet head anchoring node and the root-like flexible chain form an integrated wall protection system.

[0009] Preferably, the method for constructing the sidewall of a coal seam roadway further includes the following steps: S5. After the integrated wall protection system has been fully consolidated and reached the design strength, conduct gas index and wall displacement monitoring and testing.

[0010] Preferably, in step S1, the bottom of the borehole is enlarged to form a bottom anchor point after grout is injected into the borehole.

[0011] Preferably, in step S2, the grout is a two-component polymer grout made by mixing grouting material A and material B, and the volume ratio of material A to material B is 1:0.8~1.2.

[0012] Preferably, material A comprises, by mass percentage: 60%~75% epoxy-modified polyurea semi-prepolymer, 12%~18% nanoparticles, and the remainder being additives.

[0013] Preferably, component B comprises, by weight percentage: 45%~65% polyamine curing agent, 25%~40% resin, and the remainder being additives.

[0014] Preferably, the properties of the injected grout after curing are: elongation at break ≥ 400%, tensile strength ≥ 18 MPa, and adhesion force at the coal interface ≥ 10 MPa.

[0015] Preferably, in step S3, the node construction window period is the 5-10 minute settling period after grouting.

[0016] Preferably, in step S4, the spraying thickness of the TSL reinforcing coating is controlled to be 3mm~8mm, and the spraying operation is completed within 1h~4h after the initial setting of the flexible rivet head anchoring node.

[0017] Preferably, the TSL reinforcing coating and the grouting material are made of the same polymer material system.

[0018] On the other hand, the present invention proposes a coal roadway sidewall protection structure, which is constructed using the above-mentioned coal roadway sidewall protection construction method. It includes root-like flexible chains embedded in the deep fissures of the coal body, flexible rivet head anchoring nodes integrally formed and connected to the orifice end of the flexible chains, and a TSL reinforcing coating that fully covers the surface of the roadway coal sidewall and the outer surface of the flexible rivet head anchoring nodes. The root-like flexible chains, the flexible rivet head anchoring nodes, and the TSL reinforcing coating together constitute a composite wall protection force system.

[0019] Preferably, the boreholes on the coal face of the roadway are distributed in a grid or fan shape.

[0020] In another aspect, the present invention proposes a coal seam roadway sidewall construction system, including a special underground compressed air driven liquid injection device for grouting in step S2 and a mist nozzle for spraying the TSL reinforcement coating in step S4.

[0021] The present invention achieves the following technical effects compared to the prior art: This invention proposes a method for constructing stabilizing coal seam sidewalls, addressing the core challenges of existing support technologies, such as the large deformation of sidewalls in deep, high-stress, soft, and outburst-prone coal seams, the high risk of gas outbursts, the disconnect between internal and external reinforcement, the brittle fracture of rigid components, and the easy peeling of surface coatings. The method employs a three-in-one fully flexible composite wall protection scheme: deep, root-like flexible chains are formed through high-pressure grouting in boreholes; flexible rivet-head anchoring nodes are constructed integrally with the deep chains, utilizing the properties of the grouting material before initial setting; and a thin TSL spray coating on the surface achieves a dual coupling of chemical cross-linking and physical encapsulation with the anchoring nodes, forming a fully tough wall protection system without any rigid components. Specific beneficial effects are as follows: (1) Pioneering a three-in-one fully flexible linkage structure of “inner cable-node-outer membrane” This is the most core and substantial feature of this invention. Existing technologies all involve independent internal reinforcement and external sealing, or rely on rigid shell molds or metal meshes to achieve force transmission. This invention innovatively transforms the "residual liquid at the injection pipe head + overflow and extension of slurry material" into a core load-bearing anchoring structural component (flexible rivet head anchoring node), completely opening up the force transmission path between the deep shear resistance system (root-like flexible chains) and the shallow tensile resistance system (TSL reinforced coating), achieving integrated and coordinated support from the inside out.

[0022] (2) Construct a fully flexible, large deformation pressure relief system without rigid components The wall protection system constructed in this invention contains no traditional rigid anchoring components such as metal anchor bolts, anchor cables, or trays. The deep, root-like flexible chains, flexible rivet head anchoring nodes, and TSL reinforcing coating all possess extremely high elongation at break (core material ≥400%). Under deep, high ground stress, even if the coal face undergoes severe expansion deformation exceeding 300mm, the entire wall protection system will not experience localized stress concentration or brittle fracture points. Instead, it maintains a "fully ductile" state, synchronously following the deformation of the coal body, achieving "guided pressure relief" without instability. This completely breaks the technical prejudice in the field that "anchoring force must rely on rigid components."

[0023] (3) Construct a seamless dual-blocking and anti-breakout mechanism The internal root-like flexible chains fill the micro-fractures to form the first barrier against gas outbursts, while the external dense TSL reinforcing coating forms the second barrier. The core breakthrough lies in the chemical cross-linking and physical encapsulation between the flexible rivet head anchoring nodes and the TSL reinforcing coating, which completely eliminates microscopic permeability gaps between the first and second barriers, forming an integral protective shell with extremely high airtightness. This greatly reduces the risk of abnormal gas outbursts and outbursts in soft, outburst-prone coal seams.

[0024] (4) Construction procedures have been greatly simplified and work efficiency has been significantly improved. The original cumbersome multi-process and multi-trade collaborative operation of "drilling-threading-grouting-plating-netting-spraying" has been simplified into a continuous chemical construction operation of "grouting-heading-spraying" without rigid attachments. The construction time per meter of tunnel has been reduced by more than 60%, which has greatly reduced the safety risks and labor costs of underground operations.

[0025] The coal seam roadway sidewall stability protection structure formed by the above construction method is a fully flexible and synergistic wall protection system consisting of root-like flexible chains, flexible rivet head anchoring nodes, and TSL reinforcement coating. It not only eliminates rigid metal anchoring components, but also seamlessly couples the deep grouting solidified body with the surface thin spray layer through physical and chemical means. It can simultaneously achieve coordinated control of large deformation of the roadway sidewall and efficient gas sealing. It is suitable for sidewall support and disaster prevention in deep mine rock gate coal exposure and soft outburst coal seam roadway excavation.

[0026] The coal roadway sidewall construction system proposed in this invention can implement the above-mentioned rigid metal anchoring components, seamlessly couple the deep grouting solidified body with the surface thin spray layer through physical and chemical means, and simultaneously achieve large deformation pressure relief support and efficient gas sealing collaborative wall construction method. The whole system has a simple structure, low operating cost, and good economic benefits. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a construction flowchart of the coal seam roadway sidewall construction method disclosed in an embodiment of the present invention; Figure 2 This is a front view of the coal seam roadway sidewall protection structure disclosed in an embodiment of the present invention; Figure 3 for Figure 2 Schematic diagram of CC cross-section structure; Figure 4 This is a structural schematic diagram of the coal seam roadway sidewall protection construction system disclosed in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the mist nozzle disclosed in an embodiment of the present invention.

[0029] In the figure, the attached labels are: 100 - coal seam roadway sidewall protection structure; 200 - underground compressed air driven special liquid injection equipment; 300 - mist nozzle; 1-TSL reinforced coating; 2-Pre-formed position of flexible rivet head on wall surface; 2a-Flexible rivet head anchoring node; 3-Roadway; 4-Flexible polymer sealing device; 5-Quick connector for injection pipe; 6-Return pipe; 7-Return pipe pressure gauge; 8-Return pipe valve; 9-Injection pipe; 10-Root-like flexible chain; 11-Ellipsoidal hole bottom anchoring point; 12-Coal seam fracture; 13-Coal seam; 14-Borehole; 15-Underground transformer substation; 16-Visual controller; 17-Cable; 18-A material feed valve; 19-A material feed pipeline; 20-A material storage tank; 21-A material dispersion monitoring and mixing device; 22-A material suction pipe; 23-A material flow rate and velocity monitoring meter; 24-Underground first compressed air inlet pipeline; 25-First compressed air pipeline valve; 26-First air velocity and flow meter; 27-First multi-functional air pump; 28-A material conveying pipe; 29-A material conveying pipe ball valve; 30-A material conveying pipe check valve; 31-A material conveying pipe quick connector; 32-Mixer 33-Material injection pipe; 34-Mixing chamber; 35-B material conveying pipe quick connector; 36-B material conveying pipe check valve; 37-B material conveying pipe ball valve; 38-B material conveying pipe; 39-Second multi-functional air pump; 40-Second compressed air pipeline valve; 41-Second compressed air inlet pipeline; 42-B material suction pipe; 43-B material flow rate and velocity monitoring meter; 44-B material dispersion monitoring and mixing device; 45-B material storage tank; 46-B material feed pipeline; 47-B material feed valve; 48-Mist nozzle; 49-Nozzle check valve. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] One of the objectives of this invention is to provide a novel method for constructing sidewall support in coal seams. This method not only eliminates the need for rigid metal anchoring components but also seamlessly couples the deep grouting consolidation body with the surface thin spray layer through physical and chemical means. It can simultaneously achieve coordinated control of large deformations in the sidewalls and efficient gas sealing, resulting in high construction efficiency and good safety performance. It is suitable for sidewall support and disaster prevention in deep mine rock tunnels and soft, outburst-prone coal seams, thus solving the problems existing in the prior art.

[0032] Another objective of this invention is to provide a coal roadway sidewall structure formed based on the above-described coal roadway sidewall construction method.

[0033] Another objective of this invention is to provide a coal seam roadway sidewall construction system that can implement the above-mentioned non-rigid metal anchoring components, seamlessly couple deep grouting solidified body and surface thin spray layer through physical and chemical means, and simultaneously achieve large deformation pressure relief support and efficient gas sealing collaborative wall construction method, so as to solve the problems existing in the prior art.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1 See Figure 1 This embodiment provides a method for constructing sidewall protection in coal seam roadways, specifically including the following construction steps: S1. Drilling Construction. Drill hole 14 in the coal face to be reinforced in the roadway, and enlarge the bottom of the borehole in a small area. Install a coal mine-permitted flexible polymer sealing device 4 at the borehole opening. Insert a disposable injection pipe 9 into the flexible polymer sealing device 4. After sealing, the injection pipe 9 should be exposed on the coal face surface with a predetermined length reserved to provide positioning support for the subsequent anchoring node construction. Before grouting the borehole 14, the injection pipe 9 can be connected to the injection equipment through the quick-connect plug 5.

[0036] S2. High-Pressure Grouting. A two-component polymer grout, prepared by mixing grouting materials A and B in a set volume ratio, is injected into borehole 14 at a pressure of not less than 2 MPa. The grouting termination pressure does not exceed the coal seam gas pressure + 0.5 MPa to avoid inducing gas outbursts. Driven by pressure and the capillary action of nanoparticles, the grout penetrates into the micron-level micro-fractures of the coal seam, undergoing a cross-linking and solidification reaction within the borehole and coal seam fractures. Ultimately, it forms root-like flexible chains 10 (which can also be described as "tree root-like") that are firmly embedded in the coal seam deep within the coal seam. It should be noted that the root-like flexible chains 10 on the outside of each borehole 14 can be independent or can interpenetrate with the root-like flexible chains 10 of adjacent boreholes 14 to form a large-area integrated root-like flexible chain. The specific chain structure can be controlled within a controllable range by adjusting parameters such as borehole diameter, borehole spacing, and borehole depth. For example, increasing the borehole spacing may prevent the chains of adjacent boreholes 14 from adhering together.

[0037] S3. Construction of Anchoring Nodes. After grouting, allow the grout to stand for 8-12 minutes depending on the downhole ambient temperature (10-35℃). The grout will then be surface-dry and enter a preliminary gel state. At this point, the grout inside the hole is not sticky but still possesses fluidity and high adhesion, representing the optimal window period before initial setting. At this time, remove the quick-connect plug 5 of the injection pipe, leaving the injection pipe 9 open and retaining at least 5cm of the pipe head as a positioning framework. Utilizing the high adhesion and fluidity of the grout before complete solidification, guide the residual grout overflowing from the hole opening to naturally extend around the reserved pipe head and onto the surface coal wall. Under the combined action of surface tension and adhesion, a disc-shaped flexible rivet head anchoring node 2a, with a diameter larger than the borehole opening, is formed at the hole opening. This node is integrated with the grout inside the hole (i.e., the root-like flexible chain 10). The flexible rivet head anchoring node 2a and the root-like flexible chain 10 inside the hole are made of the same material and are continuously integrally formed, without interface bonding defects, resulting in higher structural strength and better wall protection.

[0038] S4. TSL Spraying and Sealing. During the period when the active groups on the surface of the flexible rivet head anchoring node 2a are not completely deactivated, loose coal and debris on the roadway side surface are cleaned, and a permissible polymer thin-layer coating material for coal mines, such as TSL (Thin Spray-on Liner), is uniformly sprayed onto the coal face surface using high-pressure spraying equipment. During the spraying process, the TSL slurry not only completely seals the cracks and pores on the coal wall surface, but its polymer chain segments can also undergo chemical cross-linking reactions with the incompletely reacted active groups on the surface of the flexible rivet head anchoring node 2a. At the same time, the thickness of the TSL reinforcing coating 1 completely physically encapsulates the entire anchoring node, forming a dual coupling structure of chemical cross-linking and physical encapsulation between the TSL reinforcing coating 1 and the flexible rivet head anchoring node 2a. Thus, the external TSL reinforcing coating 1 is reliably anchored to the deep flexible solidified body, completely opening up the force transmission path between the deep shear system and the shallow tensile system. The root-like flexible chain cable 10, the flexible rivet head anchoring node 2a, and the TSL reinforcement coating 1 together constitute a three-in-one fully flexible and collaborative wall protection system of inner cable-node-outer membrane, without any metal anchor rods, anchor cables, or rigid anchoring components such as trays.

[0039] S5. Consolidation Curing and Effect Verification. After the fully flexible and synergistic wall protection system formed on the coal face has been completely consolidated and reached the design strength, gas index and wall displacement monitoring and verification will be carried out.

[0040] The aforementioned coal seam roadway sidewall construction method and the resulting fully flexible collaborative wall protection system abandon all traditional rigid metal anchoring components and innovatively construct a flexible rivet head anchoring node 2a integrally formed with the deep grouting body (i.e., root-like flexible chains 10). The flexible rivet head anchoring node 2a is then integrated with the surface TSL reinforcing coating 1, forming a three-dimensional, fully tough composite wall protection system integrating inner cable, node, and outer membrane. This system can simultaneously solve two core problems: controlling large deformations in soft coal seams and preventing gas outbursts. The deep root-like flexible chains 10 penetrate the micro-fractures of the coal seam, forming a composite shear-resistant system with the coal seam, restricting internal shear slippage. The flexible rivet head anchoring node 2a acts as a force transmission hub, transferring the anchoring force of the deep chains to the surface TSL reinforcing coating 1 (the outer membrane) without loss. The TSL reinforcing coating 1 provides full-section circumferential tension constraint, limiting surface spalling and expansion deformation of the coal seam. The entire wall support system is made of fully flexible materials with an elongation at break that is much greater than the ultimate deformation of the coal body. It coordinates deformation during the large deformation of the coal body and achieves pressure relief through the high elastic deformation of the material, while maintaining stable support resistance and eliminating stress concentration brittle fracture points.

[0041] like Figure 2 and Figure 3As shown, the deep root-like flexible chains 10 fill the micro-fractures in the coal body, which can block the gas seepage channels and form the first anti-outburst barrier. At the same time, a deep anchoring node can also be formed at the bottom of the borehole. The deep anchoring node and the root-like flexible chains 10 work together to improve the deep anchoring strength of the entire wall protection system. The dense TSL reinforcement coating 1 serves as the fully enclosed outer membrane of the entire wall protection system, which can block the gas outflow channels and form the second anti-outburst barrier. Through the chemical cross-linking and physical encapsulation of the flexible rivet head anchoring node 2a and the TSL reinforcement coating 1, the micro-interface gaps between the first and second barriers are completely eliminated, forming an integral closed shell with extremely high airtightness, which completely eliminates the risk of gas leakage along the borehole opening and interface.

[0042] As a coal seam reinforcement hole, borehole 14 is enlarged at the bottom compared to conventional cylindrical through holes, which plays a role in "strengthening" the borehole. After the material is injected and filled into borehole 14, it forms an anchoring point at the bottom of the hole. Combined with the flexible rivet head anchoring node 2a at the borehole opening, the slurry in the entire borehole 14 solidifies to form a "double-headed rivet" reinforcement body, which can improve the anchoring strength and anchoring effect of the entire wall protection system.

[0043] As a preferred embodiment of step S1, the diameter of the borehole 14 is 42mm~75mm, the depth (including the enlarged area) is 4m~8m, the spacing between adjacent boreholes 14 is 0.8m~1.5m, the sealing length of the flexible polymer sealing device 4 is not less than 800mm, and the exposed length of the injection tube 9 is 5cm~10cm.

[0044] As a further preferred option for step S1, the boreholes 14 are distributed in a rectangular grid or fan shape on the coal face.

[0045] As a further preferred embodiment of step S1, the enlarged portion at the bottom of each borehole is preferably ellipsoidal. After the grout is injected into the borehole, since the bottom of the borehole is ellipsoidal, the injected material fills the borehole 14 and forms an ellipsoidal anchor point at the bottom of the borehole.

[0046] As a preferred embodiment of step S2, the A material and the B material are mixed and then injected using a dedicated injection equipment driven by downhole compressed air.

[0047] As a preferred embodiment of step S2, the mixing volume ratio of component A to component B used in preparing the two-component polymer slurry is 1:0.8~1.2; component A comprises, by mass percentage: 60%~75% epoxy-modified polyurea semi-prepolymer, 12%~18% nanoparticles, and the remainder being additives; component B comprises, by mass percentage: 45%~65% polyamine curing agent, 25%~40% resin, and the remainder being additives.

[0048] As a preferred embodiment of step S2, the properties of the grouting material after curing should meet the following requirements: elongation at break ≥ 400%, tensile strength ≥ 18 MPa, and adhesion force at the coal interface ≥ 10 MPa.

[0049] As a preferred option for step S3, the node construction window period is 5 to 10 minutes after the grouting of borehole 14 is completed. During this window period, the grout is in the initial gel state.

[0050] As a preferred option for step S4, the thickness of the TSL reinforced coating 1 is controlled to be 3mm to 8mm. The spraying operation is completed within 1h to 4h after the initial setting of the flexible rivet head anchoring node 2a. This period is the window period during which the surface active groups have not been completely deactivated.

[0051] As a preferred option for step S4, the materials of the TSL reinforced coating 1 and the two-component polymer slurry are polymer materials of the same system, such as polyurea / epoxy modified polymer materials of the same system, so as to ensure the compatibility of chemical cross-linking of the active groups of the polymer chain segments of the two and avoid interface defects.

[0052] As a preferred option for step S5, the consolidation and curing time of the fully flexible synergistic wall protection system should be no less than 24 hours before conducting gas index and side displacement monitoring and testing.

[0053] As a preferred option for step S5, two core effect tests are mainly carried out: one is the gas control effect test, which tests the K1 value of the gas desorption index of drill cuttings and the amount of gas emitted from the coal wall; the other is the support effect test, which sets up measuring points to monitor the surface displacement of the sidewall and the coating peeling.

[0054] The above-mentioned method for constructing sidewalls in coal seams is applicable to soft, outburst-prone coal seams with a firmness coefficient f < 0.5, deep high ground stress, mining-induced pressure effects, or high-risk tunneling conditions involving coal seam exposure in rock passages. Specific examples are as follows: Implementation Example 1: Sidewall Protection of Deep, High-Stress, Soft, Outburst Coal Seam Roadways Applicable working conditions: Side support for rock tunnel excavation faces at a burial depth of 800m, coal firmness coefficient f=0.3, original rock stress 18MPa, and coal seam gas pressure 1.2MPa. Specific construction steps and parameters are as follows: Drilling construction: Reinforced boreholes with a rectangular grid layout are constructed on the side of the roadway. The borehole diameter is 90mm, the hole depth is 6m, the hole spacing is 1.2m, and borehole 14 is perpendicular to the coal side. The borehole opening is sealed with a flexible polymer sealing device 4 with a sealing length of 800mm, and the liquid injection pipe 9 is exposed 8cm above the coal side surface.

[0055] High-pressure grouting: Material A and Material B are mixed at a volume ratio of 1:1. Material A formula (mass percentage): 70% epoxy-modified polyurea semi-prepolymer, 15% nano-calcium carbonate particles, 8% toughening agent, 4% coupling agent, and 3% defoamer; Material B formula (mass percentage): 55% aliphatic polyamine curing agent, 35% epoxy resin, 5% accelerator, and 5% diluent; The material has a final setting elongation at break of 450%, a tensile strength of 22 MPa, and an adhesion to coal body of 12 MPa; The grouting pressure is 3 MPa, and the grouting termination standard is that the grouting pressure is stabilized at 3 MPa for 5 minutes.

[0056] Anchoring node construction: After grouting is completed and left to stand for 8 minutes, when the mixture is in a gel state, cut off the grouting pipe 9, leaving a 4cm pipe head, and guide the overflow grout to extend and form a disc-shaped flexible rivet head anchoring node 2a with a diameter of 180mm and a thickness of 15mm, which is integrally formed with the root-like flexible chain 10 in the hole.

[0057] TSL spraying linkage sealing: Within 2 hours after the initial setting of the flexible rivet head anchoring node 2a, clean the loose coal on the coal wall and spray the TSL reinforcement coating 1, which is the same system as the grouting material, with a thickness of 5mm, to achieve chemical cross-linking and physical encapsulation with the node.

[0058] Curing and inspection: After curing at room temperature for 24 hours, the wall protection construction is completed.

[0059] Implementation Example 2: Sidewall Protection of Shimen Coal Uncovering Face Applicable working conditions: Side support for a coal seam uncovering face at a depth of 1000m, with a coal firmness coefficient f=0.2 and a coal seam gas pressure of 1.8MPa, where the requirements for outburst prevention are extremely high. Specific construction parameters are adjusted as follows: borehole 14 has a diameter of 113mm, a depth of 8m, and a spacing of 0.8m, arranged in a fan shape; grouting pressure is 4MPa; flexible rivet head anchoring node 2a is disc-shaped with a diameter of 220mm and a thickness of 20mm; TSL reinforcing coating 1 has a thickness of 8mm; the remaining construction steps and material formulas are consistent with Implementation Example 1 and will not be repeated here.

[0060] Implementation Example 3: Dynamic Pressure Affects Sidewall Protection in Mining Roadways Applicable working conditions: Burial depth 600m, coal firmness coefficient f=0.4, side support of mining roadways frequently affected by mining dynamic pressure. Specific construction parameter adjustments: Borehole 14 diameter 75mm, hole depth 4m, hole spacing 1.5m; grouting pressure 2MPa; flexible rivet head anchoring node 2a is disc-shaped with a diameter of 150mm and a thickness of 10mm; TSL reinforcing coating 1 thickness 3mm; the remaining construction steps and material formulas are consistent with implementation example one, and will not be repeated here.

[0061] All materials used in the implementation examples meet the safety standards for flame retardancy and anti-static properties in underground coal mines.

[0062] In summary, the coal seam roadway sidewall stability protection construction method proposed in this invention addresses the core pain points of existing support technologies, such as the large deformation of the sidewalls and high risk of gas outbursts in deep, high-stress, soft, and protruding coal seams, the disconnect between internal and external sealing, the brittle fracture of rigid components, and the easy peeling of surface coatings. It adopts a three-in-one fully flexible composite wall protection scheme of "internal cable-node-outer membrane": deep root-like flexible chains 10 are formed through high-pressure grouting in boreholes; flexible rivet head anchoring nodes 2a, integrally formed with the deep chains, are constructed using the properties of the grouting material before initial setting; and a double coupling of chemical cross-linking and physical encapsulation is achieved between the surface TSL thin spray coating and the anchoring nodes, forming a fully tough wall protection system without any rigid components. Furthermore, the deep root-like flexible chains 10 in boreholes 14 can naturally form according to the natural gaps and structures in the deep sidewalls, possessing reliable gripping force. The deep root-like flexible chains 10 in adjacent boreholes 14 can also interpenetrate and connect, further enhancing the support strength of the entire wall protection system. The aforementioned fully resilient wall support system can simultaneously achieve coordinated control of large deformations on the roadway sidewalls and efficient gas sealing. It has high construction efficiency and good safety performance, and is suitable for sidewall support and disaster prevention in deep mine rock gate coal uncovering and soft outburst coal seam roadway excavation.

[0063] Example 2 like Figure 2 and Figure 3 As shown, this embodiment proposes a sidewall protection structure for a coal seam roadway, constructed using the method described in Embodiment 1. See details... Figure 1 and Figure 2 The wall protection structure includes root-like flexible chains 10 embedded along deep fissures in the coal seam, flexible rivet head anchoring nodes 2a integrally formed and connected to the orifices of the flexible chains, and a TSL reinforcing coating 1 that fully covers the surface of the coal face and the outer surface of the flexible rivet head anchoring nodes 2a. The root-like flexible chains 10, the flexible rivet head anchoring nodes 2a, and the TSL reinforcing coating 1 together constitute a fully flexible composite wall protection system without rigid metal components. The flexible rivet head anchoring nodes 2a serve as the force transmission coupling hub between the deep chains and the surface TSL reinforcing coating 1. The inner and outer structures form a sealed whole through chemical cross-linking and physical encapsulation. This coal seam roadway sidewall protection structure can meet the stability protection requirements of soft coal seam roadways.

[0064] On the surface of the coal seam in the roadway, each of the 14 drilled holes can be used Figure 2 The grid-like distribution shown can also be a fan-shaped or circular array distribution.

[0065] See Figure 2 The dark gray area represents TSL reinforcement coating 1, and the white area represents the surface of the coal seam body in the roadway that is not covered by TSL reinforcement coating 1.

[0066] Example 3 This embodiment proposes a coal seam roadway sidewall construction system, including an underground compressed air driven special grouting device 200, which is used to mix material A and material B and then perform grouting, mainly executing step S2.

[0067] See the structure of the downhole compressed air driven special fluid injection equipment 200. Figure 4 It includes an AB material mixing grouting unit, which includes an A material feeding path, a B material feeding path, and a mixing spraying assembly. The mixing spraying assembly includes a mixing chamber 33 and a mixing material injection pipe 32 connected to the mixing chamber 33. The mixing material injection pipe 32 is used to connect to the injection pipe at the borehole opening through a quick-connect fitting. The A material feeding path and the B material feeding path are both connected to the mixing chamber 33 and are used to deliver A material and B material to the mixing chamber 33, respectively. After the A material and B material are mixed in the mixing chamber 33, they are output through the mixing material injection pipe 32.

[0068] like Figure 4 As shown, the A material feeding path includes an A material storage tank 20, an A material suction pipe 22, a first multi-functional air pump 27, and an A material conveying pipe 28 connected in sequence; the A material storage tank 20 is connected to an A material feeding pipe 19, which is used to connect to an external A material supply source, and an A material feeding valve 18 is installed on the A material feeding pipe 19; an A material dispersion monitoring and stirring device 21 is installed inside the A material storage tank 20, which is used to stir the A material in the A material storage tank 20 and monitor the A material dispersion; the A material suction pipe 22... The first multi-functional air pump 27 is connected to a flow rate and velocity monitoring meter 23 for material A; the first underground compressed air inlet pipe 24 is connected to the first underground compressed air inlet pipe 24, which is equipped with a first compressed air pipe valve 25 and a first air velocity and flow meter 26; the material A conveying pipe 28 is equipped with a material A conveying pipe ball valve 29 and a material A conveying pipe check valve 30, which is used to prevent material A backflow. The material A conveying pipe 28 is sealed and plugged into the material A inlet of the mixing chamber 33 through a quick-connect plug 31. When the first multi-functional air pump 27 is turned on, material A with specific components (such as 60%~75% epoxy modified polyurea semi-prepolymer, 12%~18% nanoparticles, and the balance being additives) and uniformly mixed in the material A storage tank 20 can be pumped to the mixing chamber 33.

[0069] like Figure 4As shown, the material B feeding path includes a material B storage tank 45, a material B suction pipe 42, a second multi-functional air pump 38, and a material B conveying pipe 37 connected in sequence; a material B feeding pipe 46 is connected to the material B storage tank 45, which is used to connect to an external material B supply source, and a material B feeding valve 47 is installed on the material B feeding pipe 46; a material B dispersion monitoring and stirring device 44 is installed inside the material B storage tank 45, which is used to stir the material B in the material B storage tank 45 and monitor the dispersion of the material B; the material B suction pipe 42... The upper part is connected to a flow rate and velocity monitoring meter 43 for material B; the second multi-functional air pump 38 is connected to a second underground compressed air inlet pipe 40, which is equipped with a second compressed air pipe valve 39 and a second air velocity and flow meter 41; the material B conveying pipe 37 is equipped with a material B conveying pipe ball valve 36 and a material B conveying pipe check valve 35. The material B conveying pipe check valve 35 is used to prevent material B backflow. The material B conveying pipe 37 is sealed and plugged into the material B inlet of the mixing chamber 33 through a material B conveying pipe quick connector 34. When the second multi-functional air pump 38 is turned on, the material B, which contains specific components (such as 45%~65% polyamine curing agent, 25%~40% resin, and the balance being additives) and is uniformly mixed, can be pumped to the mixing chamber 33.

[0070] The coal seam roadway sidewall construction system is also equipped with an underground substation 15 and a visual controller 16 electrically connected to the underground substation 15. The visual controller 16 is connected to the AB material mixing grouting unit via cable 17 to control the grouting process, especially to control the degree of material mixing in the A and B material storage tanks according to the material dispersion.

[0071] The downhole compressed air driven special grouting equipment 200 is also equipped with a return pipe 6, which is connected to the mixture injection pipe 32. The return pipe 6 is also equipped with a return pipe pressure gauge 7 and a return pipe valve 8. When in use, the return pipe valve 8 remains open. The return pipe 6 is mainly used to determine whether the borehole is full: firstly, during construction, the grouting pipe is inserted to the bottom of the hole and grout is injected until pure grout emerges from the return pipe 6, indicating that the target area has been filled with grout, and grouting can be stopped. Secondly, before or in the early stages of grouting, the return pipe 6 can be used to drain stagnant water from the hole. Pressurized grout can force excess water in the hole out through the return pipe valve 8. In some grouting devices, the return pipe 6 also serves as an air vent to ensure that the grout fills the hole densely and avoids the formation of voids.

[0072] See Figure 5The coal seam roadway sidewall construction system is also equipped with a mist nozzle 300, which includes a mist nozzle 48 and a nozzle one-way valve 49 located at the tip outlet of the mist nozzle 48. This mist nozzle 300 can be used in step S4 as a high-pressure spraying device to uniformly spray a permissible polymer thin-film coating material onto the coal seam surface to form a TSL reinforcing coating. It can also be used in the aforementioned underground compressed air driven special liquid injection equipment 200 to spray material A and material B into the mixing chamber 33, improving the mixing effect of materials A and B. Specifically, the mist nozzle 300 can be installed at the outlet end of the material B conveying pipe 37 and the outlet end of the material A conveying pipe 28, respectively.

[0073] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0074] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for constructing sidewall protection in coal seam roadways, characterized in that, Including the following steps: S1. After drilling holes for the construction of the coal face to be reinforced in the roadway, seal the holes and insert an injection pipe. The injection pipe is exposed on the surface of the coal face and a set length is reserved. S2. Grout is injected into the borehole through the injection pipe so that the injected grout penetrates into the coal body fissures and undergoes a cross-linking and solidification reaction with the grout in the borehole, forming root-like flexible chains that are embedded in the coal body in the deep part of the coal seam. S3. During the node construction window period after grouting is completed, keep the injection pipe opening open so that the residual grout in the borehole can naturally extend around the injection pipe head and on the surface coal wall, and construct a flexible rivet head anchoring node at the borehole opening that is integrated with the grout in the borehole. S4. During the period when the active groups on the surface of the flexible rivet head anchoring node are not completely deactivated, a polymer thin-film coating material is uniformly sprayed on the coal wall surface and the surface of the flexible rivet head anchoring node to form a TSL reinforcement coating on the coal wall surface. The TSL reinforcement coating, the flexible rivet head anchoring node and the root-like flexible chain form an integrated wall protection system.

2. The method for constructing sidewall protection in coal seam roadways according to claim 1, characterized in that, It also includes the following steps: S5. After the integrated wall protection system has been fully consolidated and reached the design strength, conduct gas index and wall displacement monitoring and testing.

3. The method for constructing sidewall protection in coal seam roadways according to claim 1 or 2, characterized in that, In step S1, the bottom of the borehole is enlarged to form a bottom anchor point after grout is injected into the borehole.

4. The method for constructing sidewall protection in coal seam roadways according to claim 1 or 2, characterized in that, In step S2, the grout is a two-component polymer grout made by mixing grouting material A and material B, with a mixing volume ratio of material A to material B of 1:0.8~1.

2. Material A comprises, by weight percentage: 60%~75% epoxy-modified polyurea semi-prepolymer, 12%~18% nanoparticles, and the remainder being additives; Component B comprises, by weight percentage: 45%~65% polyamine curing agent, 25%~40% resin, and the remainder being additives; The properties of the injected grout after curing are as follows: elongation at break ≥400%, tensile strength ≥18MPa, and adhesion to the coal body interface ≥10MPa.

5. The method for constructing sidewall protection in coal seam roadways according to claim 1 or 2, characterized in that, In step S3, the node construction window period is the 5-10 minute settling period after grouting.

6. The method for constructing sidewall protection in coal seam roadways according to claim 1 or 2, characterized in that, In step S4, the spraying thickness of the TSL reinforcing coating is controlled to be 3mm~8mm, and the spraying operation is completed within 1h~4h after the initial setting of the flexible rivet head anchoring node.

7. The method for constructing sidewall protection in coal seam roadways according to claim 1 or 2, characterized in that, The TSL reinforcing coating and the grouting material are made of the same polymer material system.

8. A sidewall protection structure for a coal seam roadway, characterized in that, The coal roadway sidewall protection method described in any one of claims 1 to 7 is used to construct the wall, which includes root-like flexible chains embedded in deep fissures of the coal body, flexible rivet head anchoring nodes integrally formed and connected to the orifice end of the flexible chains, and a TSL reinforcing coating that fully covers the surface of the coal sidewall and the outer surface of the flexible rivet head anchoring nodes. The root-like flexible chains, the flexible rivet head anchoring nodes, and the TSL reinforcing coating together constitute a composite wall protection force system.

9. The coal seam roadway sidewall protection structure according to claim 8, characterized in that, On the surface of the coal seam in the tunnel, the drill holes are distributed in a grid or fan shape.

10. A construction system for sidewall protection in coal seam roadways, characterized in that, It includes a downhole compressed air driven special liquid injection device for grouting in step S2 and a mist nozzle for spraying the TSL reinforcement coating in step S4.

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