A tunnel lining reinforcing structure based on FRP mesh and a method thereof

Abstract

The application belongs to the technical field of tunnel crack repair construction, and particularly relates to a tunnel lining reinforcing structure based on FRP mesh, which is used for being arranged at a cracked part in a tunnel lining and being covered on a chiseled area around the cracked part, and comprises a first steel pipe, a second steel pipe, an FRP mesh, a first fixing member and a second fixing member, a plurality of the second steel pipes are arranged at intervals along a path of the cracked part, and a plurality of the first steel pipes are arranged at intervals on both sides of the path of the cracked part; the outer surface of the chiseled area is attached with the FRP mesh which is matched with the shape of the chiseled area, the FRP mesh is penetrated by each of the first steel pipe and the second steel pipe, and the first fixing member abuts the FRP mesh on the outer surface of the chiseled area. The reinforcing structure can effectively solve the problem that the current repair of the cracked part on the tunnel surface is not complete, the crack cannot be repaired in depth, and water seepage still exists in the repaired part in the later period. The application further discloses a tunnel lining reinforcing method based on the FRP mesh.

Description

Technical Field

[0001] This invention belongs to the field of tunnel crack repair construction technology, specifically relating to a tunnel lining reinforcement structure and method based on FRP grid. Background Technology

[0002] Tunnel lining reinforcement is a crucial aspect of tunnel engineering, primarily aimed at ensuring the safety, stability, and durability of tunnels. It is essential for guaranteeing normal tunnel use and extending their service life. Current tunnel lining reinforcement methods typically include bonding (tensioning) steel plates, adding arch supports, bonding fiber cloth, and high-performance concrete reinforcement. Among these, FRP (fiberglass reinforced plastic) mesh, a novel material, is increasingly widely used in engineering projects due to its high strength, lightweight, corrosion resistance, and durability. It provides excellent tensile strength in structural reinforcement and, when combined with cement-based materials, enhances the overall structural performance. For example, a Chinese patent discloses a method and apparatus for reinforcing tunnels using FRP mesh and UHPC concrete (patent publication number: CN114718604A). The cracked parts of the tunnel surface are cleaned and roughened. An FRP mesh is installed on the roughened inner arc surface and fixed to the tunnel surface with bolts. Then, ultra-high performance concrete is poured and cured. This fully utilizes the excellent characteristics of FRP mesh and the high strength, good durability, and strong interfacial adhesion of ultra-high performance concrete, effectively improving the stress performance of damaged parts of the tunnel lining and enhancing the bearing capacity and durability of the lining.

[0003] While the aforementioned technical solution provides a method and apparatus for tunnel lining reinforcement, the use of a roughening machine to roughen the tunnel surface not only generates significant noise and vibration but also produces a large amount of dust, affecting the health of construction workers. Furthermore, the roughening machine causes impact and vibration to the concrete surface, potentially damaging the internal structure of the concrete, such as creating micro-cracks, scratching the surface of reinforcing bars, and causing bending, thus affecting the joint strength and durability and exacerbating the size of cracks within the tunnel. Moreover, simply installing FRP mesh and spraying concrete on the outer surface of the cracks is insufficient to seal deep cracks, resulting in limited repair effectiveness. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a tunnel lining reinforcement structure and method based on FRP grid, which solves the problem that the current repair of cracked parts on the tunnel surface is incomplete, cannot penetrate into the cracks for repair, resulting in water seepage in the repaired parts and easy detachment of the repaired parts.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A tunnel lining reinforcement structure based on FRP mesh is used to reinforce cracked areas within the tunnel lining and to cover roughened areas surrounding these cracked areas. The structure includes a first steel perforated pipe, a second steel perforated pipe, an FRP mesh, a first fastener, and a second fastener. Multiple second steel perforated pipes are spaced apart along the path of the cracked area to ensure support at different locations. Multiple first steel perforated pipes are spaced apart on both sides of the path of the cracked area to enhance support and fixation strength. Each first and second steel perforated pipe has a first fastener detachably connected to its free end, which faces away from and protrudes from the tunnel lining. The outer surface of the roughened area is fitted with an FRP mesh of a shape adapted to its shape. The FRP mesh is constructed by inserting first and second steel pipes into each section and secured to the outer surface of the roughened area by a first fastener. This FRP mesh possesses excellent tensile strength and corrosion resistance, effectively covering the roughened area and enhancing the overall performance of cracked sections of the tunnel lining. Multiple first and / or second steel pipes are fitted with second fasteners movably between the first fasteners and the FRP mesh. These second fasteners can be adjusted as needed to accommodate different construction requirements. The corresponding face of the second fasteners facing the FRP mesh has protrusions for passing through adjacent pores of the FRP mesh, increasing the adhesion and connection strength of the FRP mesh. Thus, the second fasteners and their protrusions, combined with the FRP mesh, ensure that the FRP mesh firmly adheres to the outer surface of the roughened area and maintains its position by preventing movement through the first fasteners. By adopting the above-mentioned scheme, the FRP grid-based tunnel lining reinforcement structure proposed in this invention can effectively penetrate into the cracks for repair, improve the overall performance of the tunnel lining, solve various defects in the prior art, and provide a guarantee for the long-term use of the tunnel lining.

[0006] Optionally, the first and second fixing members are connected by a transmission mechanism. When the first fixing member rotates to abut the adjacent surfaces of the second fixing member, the first fixing member continues to rotate, simultaneously driving the second fixing member to rotate. This adjusts the tension of the FRP mesh by causing the protrusions to partially rotate and contract the FRP mesh. Specifically, before construction, the FRP mesh is first installed and fixed to the outer surface of the roughened area using the first fixing member and the steel perforated pipe. After initial installation, the first fixing member is rotated to abut the adjacent surfaces of the second fixing member. The first fixing member continues to rotate, driving the second fixing member to rotate accordingly. The tension of the FRP mesh is adjusted using the force of the protrusions. After ensuring that the FRP mesh is flat and taut, all fixing members are finally fixed, and concrete is poured. The advantages of this design are as follows: First, it allows for adaptive adjustment. The structural design enables construction personnel to adjust the tension of the FRP mesh in real time during the reinforcement process to adapt to different construction conditions and environmental requirements, ensuring the best reinforcement effect at each construction stage. Second, it simplifies operation. Fine-tuning of the tension can be achieved through a simple rotation operation, reducing the professional requirements for construction personnel and improving construction efficiency and safety. Third, it enhances bond strength. The optimized FRP mesh tension helps improve adhesion to the concrete surface, reducing potential problems such as water seepage and detachment in the later stages.

[0007] Optionally, the transmission mechanism can be formed by bonding, threading, screw-on connection, or slotted block abutment between the first and second fixing components. This flexible selection of transmission mechanisms, such as bonding, threading, screw-on connection, or slotted block abutment, facilitates the transmission of rotational kinetic energy, improving the adaptability and reliability of tunnel lining reinforcement structures, and making construction more efficient and easier to maintain. This flexible design balances construction safety and economy, providing solid technical support for the reinforcement of tunnel linings and other similar projects.

[0008] Optionally, the protrusions are configured in groups of two to four, arranged in one or more of the following patterns: straight line, cross, L-shape, or X-shape. This offers several advantages: firstly, enhanced tension control; different arrangements provide flexible tensioning force and areas, allowing for real-time adjustment based on the deformation characteristics of the FRP mesh to ensure it adheres tightly to the roughened surface of the tunnel lining; secondly, improved contact performance; appropriately arranging the number and pattern of protrusions enhances the bond between the FRP mesh and concrete, improving the overall strength and stability of the reinforced structure; and thirdly, strong applicability; due to the wide range of options, construction personnel can select the appropriate arrangement pattern based on the specific tunnel lining condition, crack characteristics, and construction conditions to meet the requirements of different environments.

[0009] Optionally, multiple first and second steel tubes are arranged in a matrix. This matrix arrangement achieves good mechanical property distribution, enabling the reinforced structure to effectively bear and disperse externally applied forces in multiple directions. Furthermore, this arrangement significantly improves the overall stability of the tunnel lining repair, ensuring uniform stress during construction and use, and avoiding localized overloads and weak areas. The second steel tube is vertically installed on the tunnel lining. This vertical design ensures effective vertical pressure support while resisting vertical tensile forces, preventing potential slippage or detachment. The first steel tube is obliquely installed on the tunnel lining, flaring outwards. This oblique design not only helps provide support within different height and width ranges but also increases the covering effect on the concrete structure, allowing for better adhesion of the FRP mesh. The advantages of this arrangement are as follows: First, it improves structural strength. The matrix arrangement can provide uniform and strong support in different areas of the tunnel lining, significantly improving the compressive and tensile strength of the reinforced parts and reducing the risk of crack propagation. Second, it disperses stress. Due to the oblique and vertical arrangement of the first and second steel pipes, the forces transmitted to the concrete lining can be more effectively dispersed, reducing damage caused by local stress concentration. Third, it enhances stability. During tunnel construction, due to the complex tunnel environment, the rationally arranged steel pipes can firmly connect the FRP grid, enhancing overall durability.

[0010] Optionally, auxiliary connectors are also included for connecting adjacent first steel pipes, and / or adjacent second steel pipes, and / or adjacent first and second steel pipes. This design enhances the mutual support and overall stability between the steel pipes. Each auxiliary connector is abutted against the FRP mesh on its corresponding face facing the tunnel lining. This design effectively transfers tension to the FRP mesh, improving the bond between the FRP mesh and the concrete, thereby enhancing the strength and durability of the overall structure. The auxiliary connectors are equipped with connecting rings for the insertion of the first and / or second steel pipes. These connecting rings ensure the steel pipes are securely fixed to the auxiliary connectors, helping to prevent movement and misalignment during construction and improving the reinforcement effect. The advantages of this approach are as follows: First, it enhances structural integrity. By setting auxiliary connectors between different steel pipes, the overall reinforced structure becomes more compact, effectively resisting external mechanical damage, which is especially important for controlling the deformation of tunnel lining under stress. Second, it improves load-bearing capacity. The use of connecting rings further enhances the load-bearing capacity of the steel pipes, expanding the range of external forces it can withstand and ensuring the long-term stability of the tunnel structure. Third, it facilitates construction and maintenance. The addition of auxiliary connectors optimizes the operation of construction personnel during the reinforcement process, reduces the complexity of manual measurement and alignment on site, and also facilitates later inspection and maintenance.

[0011] Optionally, each of the auxiliary connectors has multiple through holes, and these through holes are evenly spaced along the length of the auxiliary connector to ensure that the pressure applied to the roughened area is evenly distributed during fixing, improving the uniformity and stability of the fixing. Each through hole is connected to an expansion bolt for fixing the auxiliary connector to the roughened area, with one end of each expansion bolt inserted into and fixedly connected to the tunnel lining. This provides the following advantages: First, enhanced fixing strength: by setting multiple evenly spaced through holes and using expansion bolts on the auxiliary connector, effective fixing can be provided at different locations, enhancing the bond strength between the auxiliary connector and the tunnel lining, thereby improving the stability of the overall reinforced structure. Second, load-bearing capacity dispersion: the design of multiple expansion bolts effectively distributes the load to the tunnel lining, reducing single-point stress and the risk of frequent local stress concentration, which is beneficial to the durability of the structure. Third, construction flexibility: the evenly spaced through hole design allows construction personnel to flexibly adjust and select the fixing position during installation, adapting to different construction conditions, shortening construction time, and improving construction efficiency.

[0012] This invention also provides a tunnel lining reinforcement method based on FRP mesh, applied to the aforementioned FRP mesh-based tunnel lining reinforcement structure. The reinforcement method includes the following steps: S1. Based on the height of the cracked part of the tunnel lining and the construction requirements, build a stable construction platform and install the roughening device using high-pressure water jet in a suitable position. S2. Start the roughening device and use high-pressure water jet to roughen the concrete surface of the cracked part of the tunnel lining for the first time. The roughening depth should generally be controlled to expose the fresh concrete surface. After roughening, ensure that the exposed concrete surface is free of laitance and loose layer. S3. Drive multiple first steel pipes around the roughened area, and drive multiple second steel pipes evenly spaced along the path of the cracked part of the tunnel lining. One end of each first steel pipe and second steel pipe protrudes a certain distance from the surface of the tunnel lining. Then, grout each first steel pipe and second steel pipe and cure it. S4. Use high-pressure water jet to perform a second roughening treatment on the previously roughened area, focusing on roughening the concrete around each first and second steel pipe. S5. Apply an interface agent to the roughened concrete surface and lay the FRP mesh on the roughened area to ensure that one end of each first steel pipe and second steel pipe passes through the corresponding FRP mesh hole, while ensuring that the FRP mesh (6) is tightly attached to the concrete surface. S6. Install the corresponding first fastener at one end of each first steel pipe, and install the second fastener and the first fastener at one end of each second steel pipe in sequence to fix the FRP mesh to the concrete surface of the tunnel lining. Then, use a spraying device to evenly spray high-strength concrete onto the FRP mesh. The spraying thickness should meet the design requirements. During the spraying process, ensure that the mortar is tightly bonded to the FRP mesh and the concrete surface to avoid hollow areas or cracks. S7. Pass the template through one end of each first steel pipe and second steel pipe and press it tightly against the surface of the high-strength concrete. Then install a third fastener at one end of each first steel pipe and second steel pipe and fix the template to the concrete surface. S8. After the high-strength concrete has been cured, remove all the third fasteners and templates in sequence, and cut off the parts of the first and second steel pipes that protrude from the tunnel lining surface.

[0013] Thus, the FRP grid-based tunnel lining reinforcement method provided by this invention ensures the safety and effectiveness of the reinforcement project through systematic operation steps. This method not only improves the load-bearing capacity and durability of the tunnel lining but also shortens the construction cycle and reduces construction difficulty, providing a practical solution for tunnel engineering.

[0014] Preferably, in step S3, when repairing the cracked areas on the tunnel lining surface, each first steel pipe is driven into the roughened concrete area at an angle away from each other, while each second steel pipe is driven into the cracked concrete area perpendicular to the tunnel lining surface. This angled arrangement allows the first steel pipes to better distribute stress to the surrounding area of ​​the concrete lining when under load, reducing local stress concentration and improving the overall stability of the structure. This vertical arrangement helps increase the resistance to shear forces in the tunnel lining and effectively enhances the compressive strength of the concrete through linear force. Simultaneously, the vertically positioned second steel pipes ensure that their surrounding area cooperates with the first steel pipes, providing additional vertical support and improving the overall reinforcement effect. The advantages of this design are as follows: First, it improves mechanical properties. The inclined placement of the first steel pipe and the vertical placement of the second steel pipe optimize the connection between the steel pipe and the concrete, thereby enhancing mechanical properties and improving resistance to deformation. Second, it enhances stability. The inclined placement of the first steel pipe helps to disperse the stress applied to the reinforced area, reducing further crack propagation caused by local overload and increasing the overall stability of the structure. Third, it has strong adaptability. This layout can not only adapt to different types of tunnel cracking sites, but also flexibly respond to the impact of the external environment on the tunnel's bearing capacity.

[0015] Preferably, in step S6, auxiliary connectors are placed between adjacent first fasteners. This arrangement ensures that the auxiliary connectors provide additional support between the first fasteners, thereby enhancing the fixing strength and overall effect of the FRP mesh. The FRP mesh is then fixed and tightly adhered to the outer surface of the roughened area, allowing direct pressure to be applied to the FRP mesh, which helps improve the bonding performance between the FRP mesh and the tunnel lining. Expansion bolts are installed on the auxiliary connectors to fix them to the tunnel lining corresponding to the roughened area. The advantages of this arrangement are: firstly, improved bonding strength. By adding auxiliary connectors between the FRP mesh and the tunnel lining, not only is the bonding between the two enhanced, but the stress condition of the FRP mesh is also improved, helping to reduce the risk of later structural failure; secondly, uniform pressure distribution. The auxiliary connectors spanning adjacent first fasteners can more evenly distribute the pressure applied to the FRP mesh, avoiding localized tearing caused by pressure concentration; and thirdly, enhanced construction efficiency. The installation of auxiliary connectors facilitates quick and effective fixing of the FRP mesh, improving construction efficiency and reducing the need for subsequent adjustments.

[0016] The beneficial effects of this invention are mainly reflected in the following aspects: 1. Crack Treatment and Control: Multiple second steel perforated pipes were driven into the cracked area, and each pipe was grouted to fill the crack. This measure not only fundamentally solved the problem of crack formation but also effectively prevented further crack propagation. Multiple first steel perforated pipes were also driven obliquely around the cracked area to prevent localized stress concentration. These first pipes, in conjunction with the second steel perforated pipes, ensured the FRP mesh was fixed to the outer surface of the roughened area. This synergistic effect improved the overall load-bearing capacity and effectively prevented the risk of detachment from the repaired area.

[0017] 2. Tension Adjustment and Adhesion Improvement: First and second fixing members are fitted onto the outer surface of the second steel perforated pipe and / or the first steel perforated pipe, with multiple protrusions designed to insert into the gaps between adjacent FRP meshes. When the first and second fixing members engage via a transmission mechanism, the tension of the FRP mesh can be adjusted simply by tightening the first fixing member. Simultaneously, the auxiliary connectors ensure that the FRP mesh adheres tightly to the roughened surface, preventing hollow areas or peeling. This ensures sufficient adhesion between the FRP mesh and the concrete, significantly improving the synergistic load-bearing performance and the long-term durability of the structure.

[0018] In summary, it enhances the overall load-bearing capacity. Through the rational configuration and synergistic effect of multiple steel pipes and FRP mesh, it significantly improves the load-bearing capacity of the reinforced structure under various load conditions. It also improves long-term durability. The optimized connection design and material selection make the reinforced structure exhibit higher durability during long-term use, reducing performance degradation caused by fatigue, aging, etc. It also improves construction efficiency. The simplified and optimized design of the structure makes the construction process more efficient and convenient, reduces the labor intensity of construction workers, and reduces the possibility of construction errors.

[0019] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the tunnel and the roughened area structure of the present invention; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 This is a schematic diagram of the FRP mesh and the first and second steel perforated pipes of the present invention. Figure 4 This is a schematic diagram of the connection structure between the auxiliary connector and the first and second steel perforated pipes of the present invention; Figure 5 This is a schematic diagram of the structure of the second steel pipe, the first fixing member, and the second fixing member of the present invention; Figure 6 This is a vertical sectional view of the cracked portion of the present invention; Figure 7 This is a schematic diagram of the template and the third fastener structure of the present invention; Attached reference numerals: 1 Tunnel lining, 2 Cracked area, 3 Roughened area, 4 First steel pipe, 5 Second steel pipe, 6 FRP mesh, 7 First fastener, 8 Second fastener, 9 Protrusion, 10 Auxiliary connector, 11 Expansion bolt, 12 Connecting ring, 13 Through hole, 14 Third fastener, 15 Template. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0022] like Figure 1-7As shown, the present invention discloses a tunnel lining reinforcement structure based on FRP grid, including a cracked portion 2 located within the tunnel lining 1 and a roughened area 3 disposed around the cracked portion 2. The roughened area 3 is recessed into the inner surface of the tunnel lining 1, and its size is larger than and covers the cracked portion 2 of the tunnel lining 1. The roughened area 3 is rectangular or quasi-rectangular in the horizontal plane. Multiple vertically inserted drill holes are formed on the periphery of the roughened area 3, and a first steel perforated pipe 4 is placed and fixed in each drill hole along the tunnel lining 1. Multiple spaced holes are drilled along the length of the cracked section 2 of the lining 1. Each hole is vertically drilled and inserted into the cracked section 2, and a second steel perforated pipe 5 is inserted and fixed into each hole. One end of each first steel perforated pipe 4 and second steel perforated pipe 5 extends a certain distance beyond the outer surface of the tunnel lining 1 and has external threads. An FRP mesh 6 of the same shape is placed and attached to the outer surface of the roughened area 3. The protruding end of each first steel perforated pipe 4 and second steel perforated pipe 5 passes through the gaps in the FRP mesh 6 and is threaded through the holes. A first fixing member 7 is connected to the surface of the roughened area 3, and the FRP mesh 6 is fixed to the surface of the roughened area 3 under the action of each first fixing member 7. A second fixing member 8 is coaxially sleeved on the outer surface of each second steel pipe 5. The second fixing member 8 is located between the FRP mesh 6 and the first fixing member 7, and four protrusions 9 are integrally formed on the end surface of the second fixing member 8 near the tunnel lining 1, which pass through the gaps of the adjacent FRP mesh 6. A transmission mechanism is provided between the two adjacent sides of the second fixing member 8 and the first fixing member 7. The transmission mechanism may include a locking block and a locking groove that are bonded to the surface of the second fixing member 8. The locking groove and the locking block are positioned correspondingly and cooperate with each other. When the first fixing member 7 is rotated to move towards the second fixing member 8 and abut against its surface, the locking groove and the locking block cooperate. When the first fixing member 7 is rotated, the second fixing member 8 is rotated synchronously through the transmission member, which indirectly causes each protrusion 9 to drive the adjacent FRP mesh 6 to adjust the tension of the FRP mesh 6 by rotating and contracting. Of course, in different examples, the transmission mechanism can also be one or more of adhesive bonding, threaded connection or swivel connection.As shown in the figure, the cooperation of multiple first steel pipes 4 and second steel pipes 5 not only provides effective support for the FRP mesh 6, allowing it to unfold and be fixed to the outer surface of the roughened area 3, but also uses first fasteners 7 threadedly connected to the outer surfaces of the first steel pipes 4 and second steel pipes 5. Tightening these fasteners fixes the FRP mesh 6 to the outer surface of the roughened area 3, effectively preventing it from falling off after the concrete is sprayed. Furthermore, multiple evenly spaced second steel pipes 5 are driven into the cracked area 2 along its length path, and second fasteners 8 are fitted onto the steel pipes. During the tightening of the first fasteners 7 on the second steel pipes 5, the first fasteners 7, after rotating for a period of time, synchronously drive the second fasteners 8 via a transmission component. When the fixing member 8 rotates, since the surface of the second fixing member 8 is provided with four protrusions 9 that are respectively inserted into the holes of the FRP mesh 6, when the first fixing member 7 and the second fixing member 8 rotate synchronously, they will drive the adjacent FRP mesh 6 to rotate and wrap around the peripheral surface of the second fixing member 8 through the protrusions 9. This causes the adjacent FRP mesh 6 to change its tensile strength by rotating and contracting. By adjusting the tightening degree of the first fixing member 7 on each second steel tube 5, the tensile strength of the entire or partial FRP mesh 6 can be indirectly adjusted, effectively improving the strength of the concrete on the surface of the FRP mesh 6 after solidification. Of course, in different examples, the second fixing member 8 can also be sleeved on the first steel tube 4, which can also achieve the purpose of tightening the FRP mesh 6. Furthermore, the high-tensile-strength FRP mesh 6 can more effectively constrain the early plastic shrinkage and drying shrinkage of concrete, reduce the width and number of cracks, thereby improving the crack resistance of the structure, as well as the flexural and tensile strength of concrete components (such as beams and slabs), delaying structural failure, absorbing more energy, improving the ductility and impact resistance of concrete, and reducing the risk of brittle failure. In addition, multiple evenly spaced second steel pipes 5 are driven into the path along the cracked part 2. After grouting the second steel pipes 5, the internal gaps of the cracked part can be effectively filled and repaired. Through the combined action of high-strength concrete and the tensile FRP mesh 6, the connection strength between the repaired part and the roughened area 3 is further strengthened, effectively preventing the problem of the repaired part falling off.

[0023] In this embodiment, auxiliary connectors 10 are connected between the first steel pipe 4 and the adjacent second steel pipe 5. The auxiliary connectors 10 are located on the side of the FRP mesh 6 that does not contact the roughened area 3, and one side surface of each auxiliary connector 10 is in contact with the surface of the adjacent tunnel lining 1 and abuts against the FRP mesh 6. At least two ends of each auxiliary connector 10 are integrally formed with connecting rings 12. Each connecting ring 12 is sleeved on the outer surface of the corresponding first steel pipe 4 and second steel pipe 5. When each first fixing member 7 is tightened, the auxiliary connector 10 will be fixed at the same time.

[0024] As shown in the figure, one side surface of the auxiliary connector 10 conforms to the surface shape of the tunnel lining 1 in the roughened area 3. By fixing the auxiliary connector 10 between the adjacent first steel pipe 4 and the adjacent second steel pipe 5, the surface of the FRP mesh 6 can be tightly attached to the outer surface of the roughened area 3 through the auxiliary connector 10. This can offset the partial surface deformation of the FRP mesh 6 after the second fixing member 8 adjusts the tension strength of the FRP mesh 6, which will be separated from the roughened area 3 by a certain distance. This can ensure that the FRP mesh 6 and the concrete form a good mechanical interlock and chemical bond, so that the FRP mesh 6 and the concrete deform together, the stress is more uniform, and the effect of suppressing surface cracks is more significant.

[0025] In this embodiment, each of the auxiliary connectors 10 has multiple through holes 13 on its outer surface, and each through hole 13 is evenly spaced along the length of the auxiliary connector 10. Each through hole is connected to an expansion bolt 11 for fixing the auxiliary connector 10 to the roughened area 3, and one end of each expansion bolt 11 is inserted into the concrete and fixedly connected thereto.

[0026] As shown in the figure, by inserting multiple expansion bolts 11 into the surface of the auxiliary connector 10, the connection between the auxiliary connector 10 and the concrete in the roughened area 3 is made tighter, and the FRP mesh 6 can be tightly attached to the surface of the roughened area 3. This not only solves the problem of the FRP mesh 6 not being tightly attached to the surface of the roughened area 3, but also indirectly improves the connection strength between the FRP mesh 6 and the roughened area 3.

[0027] A method for reinforcing tunnel lining based on FRP mesh, applied to the aforementioned FRP mesh-based tunnel lining reinforcement structure, includes the following operational steps: S1. Based on the height of the cracked part 2 of the tunnel lining 1 and the construction requirements, build a stable construction platform and install the roughening device using high-pressure water jet in a suitable position. S2. Start the roughening device and use high-pressure water jet to roughen the concrete surface of the cracked part 2 of the tunnel lining 1 for the first time (that is, roughen the roughened area 3). The roughening depth is generally controlled to expose the fresh concrete surface. After roughening, ensure that the exposed concrete surface is free of laitance and loose layer. S3. Drive multiple first steel pipes 4 around the roughened area 3. The multiple first steel pipes 4 are arranged in a rectangular shape on the horizontal plane (of course, the multiple first steel pipes 4 can also be arranged in a circular shape on the horizontal plane). Drive multiple second steel pipes 5 evenly spaced along the path of the tunnel cracked part 2. One end of each first steel pipe 4 and second steel pipe 5 protrudes a certain distance from the surface of the tunnel lining 1. Then, grout each first steel pipe 4 and second steel pipe 5 and cure it. Each first steel pipe 4 is driven into the concrete of the roughened area 3 at an angle away from each other. Each second steel pipe 5 is driven into the concrete of the cracked part 2 perpendicular to the surface of the tunnel lining 1. S4. Use high-pressure water jet to perform a second roughening treatment on the previously roughened area 3, focusing on roughening the concrete around each first steel pipe 4 and second steel pipe 5. The roughening standard is the same as the first roughening standard. S5. Apply an interface agent to the roughened concrete surface and lay the FRP mesh 6 flat on the surface of the roughened area 3. When the FRP mesh 6 is attached to the surface of the tunnel lining 1, it should be the same size as the roughened area 3, and at the same time ensure that one end of each first steel pipe 4 and second steel pipe 5 passes through the corresponding FRP mesh 6 hole, and at the same time ensure that the FRP mesh 6 is tightly attached to the concrete surface. S6. Install the corresponding first fixing member 7 at one end of each first steel pipe 4 via thread. Install the second fixing member 8 and the first fixing member 7 in sequence at one end of each second steel pipe 5. Place auxiliary connecting members 10 between adjacent first fixing members 7, ensuring that the connecting rings 12 at both ends of the auxiliary connecting members 10 are fitted onto the outer surfaces of the corresponding first steel pipe 4 and second steel pipe 5 (the installation position of the connecting rings 12 has been described above and will not be repeated here). Then, tighten each first fixing member 7 towards the roughened area 3 to fix the FRP mesh 6 to the concrete surface of the tunnel lining 1. Then, use a spraying device to evenly spray high-strength concrete onto the FRP mesh 6. The spraying thickness should meet the design requirements. During the spraying process, ensure that... The mortar should bond tightly with the FRP mesh 6 and the concrete surface to avoid hollow areas or cracks. The spraying direction should be perpendicular to the sprayed surface, and the distance between the nozzle and the sprayed surface should be controlled at about 1.0m. The spraying speed should be moderate, and the shotcrete should be applied in layers. The thickness of each layer should be determined according to the setting time of the concrete and the spraying location. The smooth surface of the roughened area 3 after shotcreting should be flush with the original concrete surface of the tunnel lining 1. Among them, the first fastener 7, the second fastener 8, the connecting ring 12, and the auxiliary connector 10 are all covered with high-strength concrete and permanently embedded in the roughened area 3. Therefore, for cost considerations, the first fastener 7, the second fastener 8, the connecting ring 12, and the auxiliary connector 10 can all be made of plastic material for single use. S7. After the concrete spraying is completed, the template 15 is passed through one end of each first steel pipe 4 and second steel pipe 5 and is tightly attached to the roughened area 3 where the high-strength concrete is sprayed. The surface of the template 15 should be in contact with the outer surface of the tunnel lining 1. Then, the third fastener 14 is installed at one end of each first steel pipe 4 and second steel pipe 5 by thread, and the template 15 is fixed to the concrete surface. S8. After the high-strength concrete has been cured, remove all the third fasteners 14 and templates 15 in sequence, and cut off the parts of the first steel pipe 4 and the second steel pipe 5 that protrude from the surface of the tunnel lining 1.

[0028] The above-mentioned scheme, along with the FRP mesh-based tunnel lining reinforcement structure and method, has the following technical innovations: Firstly: A deep crack repair structure based on the synergy of FRP mesh and steel pipe. This invention solves the problems of incomplete repair and easy detachment due to water seepage in existing technologies by arranging a second steel perforated pipe along the crack path (for grouting and filling deep cracks) and arranging a first steel perforated pipe at an angle on both sides (for dispersing stress), combined with FRP mesh covering the roughened area, forming a synergistic structure of "internal grouting repair + external mesh reinforcement". It also brings significant progress: this structure can effectively prevent crack extension and water seepage, improve load-bearing capacity and durability, and solve the problems of "micro-crack damage" and "repair site detachment" mentioned in the background technology.

[0029] Secondly: Adjustable FRP mesh tension mechanism This invention achieves real-time adjustment of FRP mesh tension through a transmission mechanism (such as threads, slots, or blocks) between the first and second fixing members, and through protrusions on the second fixing member passing through the FRP mesh pores. Thus, this invention achieves dynamic tensioning through a simple rotational operation, ensuring a tight fit between the FRP mesh and the concrete surface, avoiding voids and poor adhesion. It also brings significant improvements: this mechanism enhances the synergistic stress-bearing performance of the FRP mesh and concrete, strengthens crack resistance and durability, and simplifies construction operations.

[0030] Thirdly: Auxiliary connectors enhance overall stability. This invention incorporates auxiliary connectors between adjacent steel pipes, secured by connecting rings and expansion bolts, further distributing stress evenly and enhancing the bonding strength of the FRP mesh. Specifically, the auxiliary connectors act as "bridges," connecting multiple steel pipes to form a mesh support structure—a method not commonly used in existing technologies. The through-hole and expansion bolt design ensures uniform fixing and construction flexibility. It also brings significant improvements: enhancing the overall structural integrity and load-bearing capacity, reducing localized stress concentrations, and meeting the long-term stability requirements of tunnel engineering.

[0031] Fourthly: The construction method of roughening and grouting in stages. The reinforcement method of this invention includes two roughening processes (S2, S4), grouting of the steel perforated pipe (S3), FRP mesh tensioning (S6), and formwork fixing (S7), ensuring progressive repair and deep coverage. This effectively solves the problem of existing methods that often use a single roughening process, which can easily lead to internal damage to the concrete. This invention, through two roughening processes (with a focus on the area around the steel perforated pipe) and grouting curing, enhances the repair depth and interfacial adhesion. It also brings significant improvements: optimized process flow, improved construction efficiency and quality, and avoids the problems of "dust, noise, and micro-cracks" mentioned in the background art.

[0032] In summary, this invention solves key technical problems such as deep crack treatment, bond strength, and long-term durability in tunnel lining repair through comprehensive innovation in structural design, tensioning mechanism, auxiliary connection, and construction method.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A tunnel lining reinforcement structure based on FRP mesh, characterized in that, The tool for setting up cracked areas (2) within the tunnel lining (1) and roughened areas (3) covering the periphery of the cracked areas (2) includes a first steel pipe (4), a second steel pipe (5), an FRP mesh (6), a first fastener (7), and a second fastener (8). Multiple second steel pipes (5) are spaced apart along the path of the cracked areas (2), and multiple first steel pipes (4) are spaced apart on both sides of the path of the cracked areas (2). Each first steel pipe (4) and second steel pipe (5) has a first fastener (7) detachably connected to its free end, which is away from and exposed from the tunnel lining (1). The outer surface of the roughened areas (3) is fitted with an FRP mesh (6) that matches its shape, and the FRP mesh (6) is secured by each first steel pipe (4) and second steel pipe (5). The first fixing member (7) is inserted and abuts against the outer surface of the roughened area (3); a second fixing member (8) is movably fitted on multiple first steel pipes (4) and / or second steel pipes (5) and located between the first fixing member (7) and the FRP mesh (6), and the second fixing member (8) is provided with a protrusion (9) on the corresponding surface facing the FRP mesh (6) for passing through multiple adjacent holes of the FRP mesh (6); the first fixing member (7) and the second fixing member (8) are connected by a transmission mechanism. When the first fixing member (7) is rotated to abut against the adjacent surface of the second fixing member (8), the first fixing member (7) continues to rotate and simultaneously drives the second fixing member (8) to rotate, so as to adjust the tension of the FRP mesh (6) by causing the FRP mesh (6) to rotate and contract locally through the protrusion (9); It also includes auxiliary connectors (10) for connecting multiple adjacent first steel pipes (4), and / or multiple adjacent second steel pipes (5), and / or multiple adjacent first steel pipes (4) and second steel pipes (5), and each auxiliary connector (10) is attached to and abuts against the FRP grid (6) on the corresponding face facing the tunnel lining (1), and the auxiliary connector (10) is provided with a connecting ring (12) for the first steel pipe (4) and / or the second steel pipe (5) to pass through; each auxiliary connector (10) is provided with multiple through holes (13), and each through hole is evenly spaced along the length direction of the auxiliary connector (10), and each through hole (13) is connected with an expansion bolt (11) for fixing the auxiliary connector (10) to the roughened area (3), and one end of each expansion bolt (11) is inserted into the tunnel lining (1) and fixedly connected thereto.

2. The tunnel lining reinforcement structure based on FRP mesh according to claim 1, characterized in that, The transmission mechanism is in the form of: the first fixing member (7) and the second fixing member (8) are connected by adhesive bonding, threaded connection, screw connection or slot block abutment.

3. The tunnel lining reinforcement structure based on FRP mesh according to claim 1, characterized in that, The protrusions (9) are set to two to four, arranged in one or more of the following shapes: straight, cross, L-shaped or X-shaped.

4. The tunnel lining reinforcement structure based on FRP mesh according to claim 1, characterized in that, Multiple first steel pipes (4) and second steel pipes (5) are arranged in a matrix; the second steel pipe (5) is vertically installed on the tunnel lining (1), and the first steel pipe (4) is obliquely installed on the tunnel lining (1) with outward expansion.

5. A tunnel lining reinforcement method based on FRP mesh, characterized in that: When applied to the FRP mesh-based tunnel lining reinforcement structure according to any one of claims 1 to 4, the reinforcement method includes the following steps: S1. Based on the height of the cracked part (2) of the tunnel lining (1) and the construction requirements, build a stable construction platform and install the roughening device using high-pressure water jet in a suitable position. S2. Start the roughening device and use high-pressure water jet to roughen the concrete surface of the cracked part (2) of the tunnel lining (1) for the first time. The roughening depth is generally controlled to expose the fresh concrete surface. After roughening, ensure that the exposed concrete surface is free of laitance and loose layer. S3. Drive multiple first steel pipes (4) around the roughened area (3), and drive multiple second steel pipes (5) evenly spaced along the path of the cracked part (2) of the tunnel lining (1). One end of each first steel pipe (4) and second steel pipe (5) protrudes a distance from the surface of the tunnel lining (1). Then, grout each first steel pipe (4) and second steel pipe (5) and cure it. S4. Use high-pressure water jet to perform a second roughening treatment on the previously roughened area (3), focusing on roughening the concrete around each first steel pipe (4) and second steel pipe (5); S5. Apply an interface agent to the roughened concrete surface and lay the FRP mesh (6) on the surface of the roughened area (3) to ensure that one end of each first steel pipe (4) and second steel pipe (5) passes through the corresponding FRP mesh (6) hole, while ensuring that the FRP mesh (6) is tightly attached to the concrete surface. S6. Install the corresponding first fixing part (7) at one end of each first steel pipe (4), and install the second fixing part (8) and the first fixing part (7) at one end of each second steel pipe (5) in sequence. Fix the FRP mesh (6) on the concrete surface of the tunnel lining (1). Then use a spraying device to evenly spray high-strength concrete onto the FRP mesh (6). The spraying thickness should meet the design requirements. During the spraying process, ensure that the mortar is tightly bonded to the FRP mesh (6) and the concrete surface to avoid hollowing or cracking. S7. Pass the template (15) through one end of each first steel pipe (4) and second steel pipe (5) and press it against the surface of the high-strength concrete. Then install the third fastener (14) at one end of each first steel pipe (4) and second steel pipe (5) and fix the template (15) to the concrete surface. S8. After the high-strength concrete has been cured, remove all the third fasteners (14) and templates (15) in sequence, and cut off the first steel pipe (4) and the second steel pipe (5) that protrude from the surface of the tunnel lining (1).

6. The tunnel lining reinforcement method based on FRP mesh according to claim 5, characterized in that: In step S3, when repairing the cracked part (2) on the surface of the tunnel lining (1), each first steel pipe (4) is driven into the concrete of the roughened area (3) at an angle away from each other, and each second steel pipe (5) is driven into the concrete of the cracked part (2) perpendicular to the surface of the tunnel lining (1).

7. The tunnel lining reinforcement method based on FRP mesh according to claim 5, characterized in that: In step S6, an auxiliary connector (10) is placed between adjacent first fasteners (7), and the FRP mesh (6) is fixed and attached to the outer surface of the roughened area (3); expansion bolts (11) are provided on the auxiliary connector (10) to fix the auxiliary connector (10) to the tunnel lining (1) corresponding to the roughened area (3).

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