A FRP-ECC prefabricated panel assembled reinforcing lining structure and reinforcing method based on SMA self-prestress action

Abstract

The application belongs to the technical field of tunnel engineering reinforcement, and discloses a FRP-ECC prefabricated plate assembled reinforcement lining structure and a reinforcement method based on SMA self-prestress, wherein the FRP-ECC prefabricated plate is arranged on the inner surface of the tunnel lining, an inner-ring joint is arranged between adjacent FRP-ECC prefabricated plates along the ring direction of the tunnel, the inner-ring joint is connected through a FRP reserved lap joint section, an inter-ring joint is arranged between adjacent FRP-ECC prefabricated plates along the axial direction of the tunnel, the inter-ring joint is connected through a mortise-and-tenon joint structure, the two sides of the inner-ring joint are mechanically locked through a plurality of SMA wires, and the two ends of the SMA wire are provided with SMA wire excitation sections. The three, i.e., the ring-direction FRP lap joint, the axial mortise-and-tenon joint and the SMA self-prestress, work together to form a composite reinforcement system, and the composite reinforcement system can be used for reinforcing tunnel linings with different degrees of diseases.

Description

Technical Field

[0001] This invention belongs to the field of tunnel engineering reinforcement technology, and in particular to a precast FRP-ECC precast slab reinforced lining structure and reinforcement method based on SMA self-prestressing. Background Technology

[0002] With the long-term service of tunnels, many existing tunnels have maintained basic stability in their original lining structure, but have suffered from defects such as cracking, joint damage, local leakage, and small-scale deformation in the surface or localized weak points. These defective sections are more suitable for reinforcement and repair methods that are internally bonded, lightweight, and quick to construct, which can improve the local load-bearing capacity and surface integrity of the lining while minimizing secondary damage to the existing lining and impact on operation.

[0003] Common tunnel reinforcement methods include bonding steel plates, bonding fiber-reinforced polymer (FRP) composites, and arch reinforcement. However, these methods suffer from drawbacks such as high self-weight, long construction periods, and significant construction difficulties, making them unsuitable for the rapid treatment needs of operational tunnels. In recent years, precast slab reinforcement methods have gained attention due to their advantages of factory prefabrication and faster construction speed. However, in engineering applications, they often rely on mechanical connections such as chemical anchors and connecting bolts to fix the slabs to the original lining surface, increasing disturbance to the existing lining and resulting in numerous construction steps and localized stress concentrations. For damaged sections where the original lining is largely stable, the above methods still have room for improvement in terms of low-damage and rapid reinforcement.

[0004] Shape memory alloys (SMAs) possess the characteristic of recovering deformation and generating restoring stress after heating, making them suitable for applying active prestress to structures. They show promising applications in crack closure and tension zone confinement. Existing SMA reinforcement methods often directly act on the original lining, requiring grooving the surface, embedding reinforcement, and applying excitation. For prefabricated slab reinforcement, combining the active confinement effect of SMAs with prefabricated slab splicing creates a rapid reinforcement method. However, current technologies still lack targeted solutions for the significant problems in existing tunnels, such as cracks, joint opening, leakage accompanied by cracking, and localized insufficient load-bearing capacity. Summary of the Invention

[0005] The purpose of this invention is to provide an FRP-ECC precast slab prefabricated reinforced lining structure and reinforcement method based on the self-prestressing effect of SMA, which solves the problems of rapid assembly, low-damage installation and active suppression of crack propagation in the prior art.

[0006] To achieve the above objectives, the present invention employs the following technical solution: An assembled reinforced lining structure based on the self-prestressing effect of SMA (Self-Prestressed Abrasive Motion) of FRP-ECC precast slabs includes several FRP-ECC precast slabs, inner ring joints, inter-ring joints, and SMA reinforcement. FRP-ECC precast slabs are arc-shaped precast components. FRP-ECC precast slabs are placed on the inner surface of the tunnel lining. Several FRP-ECC precast slabs are spliced ​​together along the circumferential direction of the tunnel to form a ring reinforcement layer. The ring reinforcement layer is spliced ​​together along the axial direction of the tunnel to form an overall reinforcement structure. Along the tunnel circumference, there are inner ring joints between adjacent FRP-ECC precast slabs. The inner ring joints are connected to adjacent FRP-ECC precast slabs through FRP reserved lap sections. Along the tunnel axis, there are inter-ring joints between adjacent FRP-ECC precast slabs. The inter-ring joints are connected to adjacent FRP-ECC precast slabs through mortise and tenon splicing structures. The two sides of the inner ring joints are mechanically locked by several SMA bars. SMA bar excitation sections are provided at both ends of the SMA bars.

[0007] Furthermore, a bonding and leveling layer is provided between the FRP-ECC precast slab and the inner surface of the tunnel lining. The bonding and leveling layer is a modified epoxy resin mortar.

[0008] Furthermore, the FRP-ECC prefabricated panel includes an ECC matrix and an FRP mesh, with the FRP mesh set within the ECC matrix as an intermediate layer.

[0009] Furthermore, the ECC matrix is ​​an engineering cement-based composite material, and the FRP mesh is a carbon fiber mesh, glass fiber mesh, basalt fiber mesh, or any combination thereof.

[0010] Furthermore, grooves for inner joints are provided on both sides of the inner joint, and FRP pre-reserved lap sections are set in the grooves for inner joints. The FRP pre-reserved lap sections are extensions of the FRP mesh in the grooves for inner joints. ECC grout is injected into the grooves for inner joints to form ECC wet joints.

[0011] Furthermore, the two sides of the inter-ring joint are respectively provided with an inter-ring joint tenon and an inter-ring joint mortise. The length, width and height of the inter-ring joint mortise are greater than the length, width and height of the inter-ring joint tenon. ECC grout is injected into the inter-ring joint mortise, and a sealing material is provided on the surface of the inter-ring joint.

[0012] Furthermore, the two sides of the interlocking seam are mechanically locked by several SMA ribs.

[0013] Furthermore, the SMA reinforcement is made of iron-based shape memory alloy. The SMA reinforcement is embedded in the SMA mounting groove, which is opened on the inner surface of the FRP-ECC precast slab. The two ends of the SMA reinforcement cross the inner joint or the inter-ring joint.

[0014] Furthermore, anchor bolts are installed on the initial positioning FRP-ECC precast slabs, and the anchor bolts penetrate into the tunnel lining.

[0015] A reinforcement method for an FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing includes: The tunnel section to be reinforced is measured to obtain the inner contour dimensions of the tunnel lining, the location of defects, the distribution of cracks and the clearance control requirements. Based on the measurement results, the reinforcement range, the segmentation method of FRP-ECC precast slabs and the arrangement scheme of inner ring joints, inter-ring joints and SMA reinforcement are determined. The surface of the tunnel lining to be reinforced is pretreated. According to the layout plan, prefabricated FRP-ECC prefabricated panels are installed on the surface of the tunnel lining. Adjacent FRP-ECC prefabricated panels are connected along the tunnel circumference through FRP reserved overlap sections. ECC grout is injected to form an inner ring joint. Adjacent FRP-ECC prefabricated panels are connected along the tunnel axis through mortise and tenon splicing structure to form an inter-ring joint. The pre-deformed SMA reinforcement is mechanically locked on both sides of the inner joint of the ring. The excitation section of the SMA reinforcement is electrically heated to stimulate the shape memory effect of the SMA reinforcement and generate partial recovery stress, which closes the inner joint of the ring. The SMA reinforcement is then sealed with ECC grout, thus completing the reinforcement of the FRP-ECC precast slab prefabricated reinforced lining structure based on the self-prestressing effect of SMA.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an assembled reinforced lining structure based on the self-prestressing effect of SMA (Self-Modified Abrasive Mullions) using FRP-ECC precast panels. By placing arc-shaped precast FRP-ECC panels on the inner surface of the tunnel lining, several FRP-ECC precast panels are spliced ​​together along the circumferential direction of the tunnel to form a complete ring reinforcement layer. This ring reinforcement layer is then spliced ​​together along the tunnel axis to form an integral reinforced structure. The FRP-ECC precast panels combine the high tensile strength of FRP with the high ductility and multi-crack characteristics of ECC, significantly improving the load-bearing capacity and crack control capability of the reinforcement layer. An inner ring joint is provided between adjacent FRP-ECC precast panels along the circumferential direction of the tunnel, connecting them via FRP pre-reserved lap joints. An inter-ring joint is provided between adjacent FRP-ECC precast panels along the tunnel axis, connecting them via a mortise and tenon joint structure. The two sides of the inner ring joint are mechanically locked by several SMA (Self-Modified Abrasive Mullions), with SMA reinforcement excitation sections at both ends. Active prestressing is achieved through the shape memory effect of SMA reinforcement, eliminating the need for traditional tensioning equipment. This actively closes existing cracks, inhibits the formation of new cracks, and enhances the structure's load-bearing capacity and long-term stability. This invention features differentiated designs for the inner and outer ring joints. The inner ring joints of the precast slab primarily utilize FRP lap joints and the self-prestressing effect of SMA reinforcement, while the outer ring joints primarily employ mortise and tenon structures, better reflecting the actual stress characteristics of tunnel lining. After the initial splicing of the inner ring joints, SMA reinforcement is introduced for self-prestressing, ensuring joint closure and improving its tensile load-bearing capacity. The outer ring joints utilize mortise and tenon splicing for rapid assembly, simple installation and positioning, and high splicing accuracy. This effectively transfers shear force and contact pressure, preventing misalignment and cracking of the outer ring joints, ensuring the integrity of the reinforcement layer, and promoting structural deformation coordination. This allows the FRP-ECC precast slab and tunnel lining to share the load collaboratively, avoiding problems such as unreasonable stress distribution caused by the same splicing joint. This invention utilizes the synergistic operation of circumferential FRP lap joints, axial tenon and mortise interlocking, and SMA self-prestressing to form a composite reinforcement system of "prefabricated assembly + joint reinforcement + active prestressing". This reduces damage to the original lining and has the advantages of rapid construction, active joint suppression, and overall stress improvement. It is suitable for the rapid repair and durable reinforcement of existing tunnel lining surface cracks, leakage, and local deformation.

[0017] Furthermore, the FRP-ECC precast panels used in this invention have good corrosion resistance and crack resistance, which can improve the integrity of the reinforced lining and its long-term service performance.

[0018] Furthermore, adjacent circumferential precast slabs are reliably connected by FRP pre-reserved lap joints. Combined with post-cast ECC grout, they can form an integrally stressed joint structure, which significantly improves the tensile and shear strength of the joints within the ring and prevents the joints from becoming weak points.

[0019] Furthermore, in this invention, SMA reinforcement is preferentially placed in the inner joint area of ​​the ring to solve the problem of significant tension and easy cracking within the ring; SMA reinforcement is generally not placed in the inter-ring joints, and the mortise and tenon structure is used to achieve limiting and force transmission, reducing material costs and construction complexity. For areas with more severe local defects or unfavorable stress, SMA reinforcement can be added to the mortise and tenon splicing for local reinforcement, and stress analysis can be carried out according to the actual working conditions to reasonably determine the arrangement scheme of SMA reinforcement, so as to achieve precise and efficient reinforcement.

[0020] Furthermore, in this invention, only a small number of anchor bolts are needed for the initial positioning of the FRP-ECC precast slab. The subsequent FRP-ECC precast slab mainly relies on mortise and tenon splicing, FRP lap splicing, ECC wet splicing and the self-prestressing effect of SMA reinforcement to form a whole.

[0021] Furthermore, the SMA mounting groove is arranged on the inner surface of the FRP-ECC precast slab, which reduces the disturbance to the original structure and helps to maintain the stability and integrity of the existing lining.

[0022] This invention also provides a reinforcement method for FRP-ECC precast slab prefabricated reinforced lining structures based on the self-prestressing effect of SMA (Structured Molecular Angioplasty). The method involves prefabricating arc-shaped FRP-ECC precast slabs in a factory, with on-site assembly, joint grouting, and SMA reinforcement activation primarily completed. This significantly shortens on-site construction time, reduces manual labor and wet work, and minimizes disruption to tunnel operation. Utilizing the shape memory effect of SMA reinforcement, recovery stress is generated through thermal excitation, actively tightening the inner ring joints and closing cracks. This applies circumferential prestress to the entire reinforced layer, transforming passive reinforcement into active constraint, significantly improving crack resistance and load-bearing capacity. During the tunnel's service life, the SMA reinforcement can be reactivated based on crack monitoring, and secondary thermal excitation of the SMA reinforcement excitation section releases remaining recovery stress, achieving active repair. This realizes active crack closure and secondary structural reinforcement, extending the structure's service life and solving the problem of traditional reinforcement methods' inability to provide subsequent reinforcement, ensuring the long-term operational safety of the tunnel. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the prefabricated reinforced lining structure of FRP-ECC precast slab based on the self-prestressing effect of SMA according to the present invention.

[0025] Figure 2This is a schematic diagram of the inner joint of the FRP-ECC precast slab ring and the SMA reinforcement of the present invention.

[0026] Figure 3 This is a schematic diagram of the inner joint of the FRP-ECC precast slab ring of the present invention.

[0027] Figure 4 This is a schematic diagram of the interlocking tenon and mortise splicing structure of the FRP-ECC precast panel ring of the present invention.

[0028] Figure 5 This is a schematic diagram of the self-prestressing effect of SMA reinforcement at the inner joint of the FRP-ECC precast slab ring according to the present invention.

[0029] Figure 6 This is a construction flowchart of the prefabricated reinforcement lining technology for FRP-ECC precast slabs based on the self-prestressing effect of SMA according to the present invention.

[0030] Among them: 1-tunnel lining, 2-FRP-ECC precast slab, 21-ECC matrix, 22-FRP mesh, 3-bonding leveling layer, 4-inner ring joint, 41-inner ring joint groove, 42-FRP reserved lap section, 43-ECC wet joint, 5-inter-ring joint, 51-inter-ring joint tenon, 52-inter-ring joint mortise, 6-SMA reinforcement, 61-SMA installation groove, 62-SMA reinforcement excitation section, 7-anchor bolt. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0036] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 The present invention provides an FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing, including FRP-ECC precast slab 2, bonding and leveling layer 3, inner ring joint 4, inter-ring joint 5, SMA reinforcement 6 and anchor bolt 7.

[0038] Tunnel lining 1 is the existing reinforced concrete lining structure of the tunnel, and is the object of reinforcement. FRP-ECC precast slab 2 is an arc-shaped precast component, bonded to the inner surface of tunnel lining 1 via an adhesive leveling layer 3. The adhesive leveling layer 3, using modified epoxy resin mortar, is placed between tunnel lining 1 and FRP-ECC precast slab 2 to improve the bonding quality and enhance the synergistic load-bearing performance. Multiple FRP-ECC precast slabs 2 are spliced ​​together circumferentially along the tunnel to form a complete ring reinforcement layer, and multiple rings are spliced ​​together axially along the tunnel to form an integrated reinforcement system.

[0039] The FRP-ECC precast slab 2 has an embedded FRP mesh 22 and an external ECC matrix 21. The FRP mesh 22 is placed in the middle layer of the ECC matrix 21. The FRP-ECC precast slab 2 is assembled into a complete ring along the tunnel circumferential direction according to actual working conditions, and arranged in rings along the axial direction. The ECC matrix 21 is an engineering cement-based composite material, and the FRP mesh 22 is a carbon fiber mesh, glass fiber mesh, basalt fiber mesh, or any combination thereof. The number of layers and mesh density can be set according to the stress requirements to improve local load-bearing capacity and crack control. The FRP mesh 22 provides high tensile strength, and the ECC matrix 21 provides high ductility and multi-crack cracking performance. The two work together to improve the load-bearing capacity, crack resistance, and durability of the precast slab.

[0040] The inner ring joint 4 is a joint formed by splicing the edges of adjacent FRP-ECC precast slabs 2 within the same ring. The inner ring joint 4 has an inner ring joint groove 41, which is located at the edge of the spliced ​​adjacent FRP-ECC precast slabs 2 within the same ring. Figure 3 As shown, an FRP pre-reserved overlap section 42 is provided within the inner joint groove 41. The FRP pre-reserved overlap section 42 is the portion of the FRP mesh 22 extending outward from the inner joint groove 41. The overlap of the FRP pre-reserved overlap section 42 enhances the tensile strength of the joint. The length of the FRP pre-reserved overlap section 42 is designed to ensure effective overlap when two FRP-ECC prefabricated panels 2 are joined. Figure 2 As shown, after overlapping, ECC grout is injected into the inner joint groove 41 to form an ECC wet joint 43, which further improves the integrity and shear resistance of the joint and prevents the joint from becoming a weak point in the structure. SMA installation grooves 61 are opened on both sides of the inner joint 4 of the inner surface of the FRP-ECC precast slab 2, and one is arranged at certain intervals along the circumference.

[0041] Inter-ring joint 5 is the joint formed by splicing the edges of the FRP-ECC precast slabs 2 of adjacent rings, such as... Figure 4 As shown, the inter-ring joint 5 is provided with an inter-ring joint tenon 51 and an inter-ring joint mortise 52, achieving inter-ring connection through a tenon-mortise splicing structure. The length, width, and height of the inter-ring joint mortise 52 are greater than those of the inter-ring joint tenon 51. During splicing, a small amount of ECC grout is injected into the inter-ring joint mortise 52. After normal splicing of the tenon and mortise, the grout fills the gaps, which can transmit contact pressure, prevent misalignment, and improve the waterproofness and durability of the joint. A thin layer of sealing material can also be applied to the outer surface of the inter-ring joint 5 to improve durability and waterproofness. Through the interlocking action of the inter-ring joint tenon 51 and the inter-ring joint mortise 52, the shear resistance and misalignment resistance of the inter-ring joint 5 are significantly improved, ensuring the integrity of the axial reinforcement layer. For areas with severe lining damage, the inter-ring joint 5 can adopt a tenon-mortise splicing structure as the main method, supplemented by SMA reinforcement 6 for active tightening, based on the actual situation, with SMA reinforcement 6 used for local reinforcement on the basis of the tenon-mortise splicing structure.

[0042] SMA 6 is a pre-deformed iron-based shape memory alloy rib material, which can be in the form of bars, strands, or strips, with a pre-strain of 2% to 8%. Figure 5 As shown, the SMA reinforcement 6 is embedded in the SMA mounting groove 61. The SMA reinforcement 6 is arranged perpendicularly or obliquely to the inner ring joint 4 or the inter-ring joint 5, preferably perpendicular to the inner ring joint 4 or the inter-ring joint 5. Both ends cross the inner ring joint 4 or the inter-ring joint 5 to connect to the adjacent FRP-ECC precast slab 2. The SMA reinforcement 6 is mechanically locked to the FRP-ECC precast slab 2. The mechanical locking at the ends adopts one or more combinations of clamps, pressure plates, and threaded caps. The two ends of the SMA reinforcement 6 are reserved with SMA reinforcement excitation sections 62. Thermal excitation is carried out by resistance heating, induction heating or external heat source heating. The excitation temperature is 120~250℃. Symmetrical group excitation or segmented sequential excitation is adopted to reduce local eccentric shrinkage and slab warping. The area in the SMA mounting groove 61, except for the SMA reinforcement excitation section 62, is filled with ECC grout for sealing. The SMA mounting groove 61 ensures the installation accuracy and stress reliability of the SMA reinforcement 6, and the ECC grout sealing protects the SMA reinforcement 6 and improves durability. The recovery stress generated after thermal excitation actively tightens the joint, closes the joint cracks, and forms circumferential prestress on the entire ring, improving the stress state of the lining. After thermal excitation, the 62 area of ​​the SMA reinforcement excitation section is sealed by injecting ECC grout.

[0043] Anchor bolts 7 are only installed on the first FRP-ECC precast slab 2 or a few initial positioning slabs for positioning during the installation phase. No anchor bolts 7 are installed on the remaining FRP-ECC precast slabs 2 to penetrate the existing tunnel lining. This reduces damage to the existing lining, minimizes construction disturbance to the structure, and ensures structural stability during the installation phase.

[0044] This invention also provides a reinforcement method for an FRP-ECC precast slab prefabricated reinforced lining structure based on the self-prestressing effect of SMA, such as... Figure 6 As shown, it includes the following steps: S1: Measure the tunnel section to be reinforced to obtain the inner contour dimensions of the tunnel lining 1, the location of defects, the distribution of cracks, and the clearance control requirements. Based on the measurement results, determine the reinforcement range, the segmentation method of the FRP-ECC precast slabs 2, and the layout scheme of the inner ring joints 4, the inter-ring joints 5, and the SMA reinforcement 6, etc.

[0045] S2: FRP-ECC precast slab 2 is prefabricated in the factory. Before the fabrication, the corresponding arc-shaped plate molds need to be made according to the design requirements of the inner ring joint 4, the inter-ring joint 5 and the SMA reinforcement 6, and then the FRP-ECC precast slab 2 is poured in batches.

[0046] First, the ECC substrate 21 is laid in the arc-shaped plate mold of the FRP-ECC precast slab 2, and then the FRP mesh 22 is embedded in the middle layer of the ECC substrate 21. Finally, it is formed by vibration compaction and curing.

[0047] The inner ring joint 4 is a joint formed by splicing the edges of adjacent FRP-ECC precast slabs 2 within the same ring. The inner ring joint 4 is provided with an inner ring joint groove 41, and an FRP reserved lap section 42 is provided in the inner ring groove 41. An SMA mounting groove 61 is opened on the inner surface of the FRP-ECC precast slab 2 perpendicular to the inner ring joint 4.

[0048] The inter-ring joint 5 is a joint formed by splicing the edges of the FRP-ECC precast panels 2 of adjacent rings. The inter-ring joint 5 is provided with an inter-ring joint tenon 51 and an inter-ring joint mortise 52 respectively.

[0049] S3: Clean, treat defects, perform water-stopping treatment and necessary leveling on the surface of the existing tunnel lining 1, and set an adhesive leveling layer 3 between the tunnel lining 1 and the FRP-ECC precast slab 2 to improve the bonding quality between the FRP-ECC precast slab 2 and the tunnel lining 1.

[0050] S4: Install the first FRP-ECC precast slab 2, using a small number of anchor bolts 7 for positioning. Then, install the remaining FRP-ECC precast slabs 2 within the same ring sequentially, overlapping the pre-reserved FRP lap sections 42 in the grooved joint 41 within the ring, and inject ECC grout into the groove 41 to form an ECC wet joint 43. After the ECC grout cures, it forms the ring joint 4, which has good tensile and shear strength.

[0051] Continue installing adjacent rings of FRP-ECC precast slabs 2 along the axial direction of tunnel lining 1. Inject a small amount of ECC grout into the inter-ring joint mortise 52 of the FRP-ECC precast slab 2 so that the grout fills the gaps when the inter-ring joint tenon 51 and the inter-ring joint mortise 52 are spliced. After splicing, the inter-ring joint 5 is formed. Apply a thin layer of sealing material to the outer surface of the joint to improve durability and waterproofing.

[0052] S5: After the ECC wet joint 43 reaches the set initial strength, the pre-deformed SMA rib 6 is embedded in the corresponding SMA mounting groove 61, with both ends crossing the inner ring joint 4 and then mechanically locked. SMA rib excitation sections 62 are reserved at both ends of the SMA rib 6, and the remaining parts are sealed with ECC grout. After the ECC grout cures, the SMA rib excitation sections 62 are electrically heated for the first time to activate the shape memory effect of the SMA rib 6, generating partial recovery stress, closing the inner ring joint 4, and forming a circumferential active compression effect on the entire ring. After the SMA rib 6 cools and stabilizes, the SMA rib excitation sections 62 are sealed to complete the reinforcement.

[0053] S6: During tunnel operation, if new cracks are detected in the reinforcement layer or the existing cracks are expanded, the SMA reinforcement excitation section 62 embedded in the installation groove can be electrically heated again to stimulate the shape memory effect of the SMA reinforcement 6 that has not been fully released, generating additional recovery stress to apply prestress to the structure again, closing or inhibiting crack development.

[0054] In a specific embodiment of the present invention, if the severity of the damage is significant, a double-layer or increased-density FRP mesh 22 can be configured in the FRP-ECC precast slab 2 to further improve the local load-bearing capacity and crack control capability.

[0055] In a specific embodiment of the present invention, for parts that are more subjected to tension, such as the arch crown, arch waist, or areas with concentrated defects, the number of SMA ribs 6 at the inner joint of the ring can be appropriately increased, or larger diameter SMA ribs 6 can be used to improve the active tensioning capacity.

[0056] In a specific embodiment of the present invention, for areas with severe local defects or unfavorable stress, SMA reinforcement 6 can be added to the inter-ring tenon joint for local reinforcement. Stress analysis is carried out according to the actual working conditions to reasonably determine the arrangement scheme of SMA reinforcement 6, so as to achieve precise and efficient reinforcement.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A prefabricated reinforced lining structure for FRP-ECC precast slabs based on the self-prestressing effect of SMA, characterized in that, It includes several FRP-ECC precast slabs (2), inner ring joints (4), inter-ring joints (5), and SMA reinforcement (6). The FRP-ECC precast slab (2) is an arc-shaped precast component. The FRP-ECC precast slab (2) is placed on the inner surface of the tunnel lining (1). Several FRP-ECC precast slabs (2) are spliced ​​together along the tunnel circumferential direction to form a whole ring reinforcement layer. The whole ring reinforcement layer is spliced ​​together along the tunnel axial direction to form an integral reinforcement structure. An inner ring joint (4) is provided between adjacent FRP-ECC precast slabs (2) along the tunnel circumference. The inner ring joint (4) is connected to the adjacent FRP-ECC precast slabs (2) through FRP reserved lap section (42). An inter-ring joint (5) is provided between adjacent FRP-ECC precast slabs (2) along the tunnel axis. The inter-ring joint (5) is connected to the adjacent FRP-ECC precast slabs (2) through mortise and tenon splicing structure. The two sides of the inner ring joint (4) are mechanically locked by several SMA bars (6). SMA bar excitation sections (62) are provided at both ends of the SMA bars (6).

2. The FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing as described in claim 1, characterized in that, A bonding and leveling layer (3) is provided between the FRP-ECC precast slab (2) and the inner surface of the tunnel lining (1). The bonding and leveling layer (3) is a modified epoxy resin mortar.

3. The FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing as described in claim 1, characterized in that, The FRP-ECC precast panel (2) includes an ECC substrate (21) and an FRP mesh (22), with the FRP mesh (22) set inside the ECC substrate (21) as an intermediate layer.

4. The FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing as described in claim 3, characterized in that, The ECC matrix (21) is an engineering cement-based composite material, and the FRP mesh (22) is a carbon fiber mesh, a glass fiber mesh, a basalt fiber mesh, or any combination thereof.

5. The FRP-ECC precast slab assembled reinforced lining structure based on SMA self-prestressing as described in claim 3, characterized in that, The inner joint (4) has inner joint grooves (41) on both sides. The FRP reserved overlap section (42) is set in the inner joint groove (41). The FRP reserved overlap section (42) is the extension of the FRP grid (22) in the inner joint groove (41). ECC grout is injected into the inner joint groove (41) to form an ECC wet joint (43).

6. The FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing as described in claim 1, characterized in that, The two sides of the inter-ring joint (5) are respectively provided with an inter-ring joint tenon (51) and an inter-ring joint mortise (52). The length, width and height of the inter-ring joint mortise (52) are greater than the length, width and height of the inter-ring joint tenon (51). ECC grout is injected into the inter-ring joint mortise (52). The surface of the inter-ring joint (5) is provided with sealing material.

7. The FRP-ECC precast slab assembled reinforced lining structure based on SMA self-prestressing as described in claim 1, characterized in that, The two sides of the inter-ring joint (5) are mechanically locked by several SMA ribs (6).

8. The FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing as described in claim 1 or 7, characterized in that, SMA reinforcement (6) is an iron-based shape memory alloy reinforcement. SMA reinforcement (6) is embedded in SMA mounting groove (61). SMA mounting groove (61) is opened on the inner surface of FRP-ECC precast slab (2). The two ends of SMA reinforcement (6) cross the inner joint (4) or the inter-ring joint (5).

9. The FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing as described in claim 1, characterized in that, Anchor bolts (7) are installed on the FRP-ECC precast slab (2) at the initial positioning point, and the anchor bolts (7) penetrate into the tunnel lining (1).

10. A reinforcement method for an FRP-ECC precast slab prefabricated reinforced lining structure based on SMA self-prestressing, as described in any one of claims 1 to 9, characterized in that, include: The tunnel section to be reinforced is measured to obtain the inner contour dimensions, location of defects, distribution of cracks and clearance control requirements of the tunnel lining (1). Based on the measurement results, the reinforcement range, the block division method of FRP-ECC precast slab (2) and the arrangement scheme of inner ring joint (4), inter-ring joint (5) and SMA reinforcement (6) are determined. The surface of the tunnel lining (1) to be reinforced is pretreated. According to the layout plan, prefabricated FRP-ECC prefabricated panels (2) are installed on the surface of the tunnel lining (1). Adjacent FRP-ECC prefabricated panels (2) are connected along the tunnel circumference through FRP reserved overlap section (42). ECC grout is injected to form an inner ring joint (4). Adjacent FRP-ECC prefabricated panels (2) are connected along the tunnel axis through mortise and tenon splicing structure to form an inter-ring joint (5). The pre-deformed SMA reinforcement (6) is mechanically locked on both sides of the inner joint (4). The excitation section (62) of the SMA reinforcement is electrically heated to stimulate the shape memory effect of the SMA reinforcement (6) and generate partial recovery stress, so that the inner joint (4) is closed. The SMA reinforcement (6) is sealed with ECC grout to complete the reinforcement of the FRP-ECC precast slab prefabricated reinforcement lining structure based on the self-prestressing effect of SMA.

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