Composite reinforcing method for failure of bonding glue at tower drum joint of mixed tower wind turbine generator

Abstract

The invention discloses a composite reinforcing method for failure of adhesive glue at the joint of tower barrels of a mixed tower wind turbine generator, and belongs to the technical field of wind power structure repair, the method comprises the following steps: firstly, determining a reinforcing scheme, then carrying out pretreatment on a failure area, and further injecting structural glue into failure glue seams at the joint of upper and lower concrete tower barrels to recover the interface bonding performance; the external restraint layer is wrapped by the prestressed carbon fiber cloth, so that the anti-shearing and anti-fatigue capabilities are improved; the fiber grating sensors are synchronously pasted, and prestress application and reinforcing effects are monitored in real time; then a polyurea elastomer protective layer is sprayed, so that the carbon fiber cloth is further prevented from falling off; the outermost layer is a mechanical reinforcing layer, an adjustable split steel hoop is installed, and radial pre-tightening force is applied. The strength and the fatigue life of the joint of the upper concrete tower drum and the lower concrete tower drum are improved, the operation and maintenance cost is reduced, and the method is particularly suitable for repairing the mixed tower in the offshore high-humidity and high-salt-mist environment and has the advantages of structural safety and intelligent management.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power tower structure reinforcement, and in particular relates to a composite reinforcement method for failed adhesive at a tower connection of a hybrid wind turbine generator set. Background Art

[0002] A hybrid tower wind turbine combines a concrete tower with a steel tower or other materials. This structure leverages the advantages of concrete, such as its excellent compressive strength and relatively low cost, and steel's excellent tensile strength and ease of fabrication. It can adapt to varying wind resource conditions and site requirements, and has been widely used in the modern wind power sector. For example, in low-wind-speed areas, the use of a concrete tower can increase tower height, improve the wind turbine's wind-collecting capacity, and thus enhance power generation efficiency. In hybrid tower wind turbines, adhesive is typically used to connect the upper and lower concrete tower sections. Adhesive plays a crucial role, firmly bonding the different tower sections together, transferring loads and ensuring structural integrity and stability. Through adhesive, the various sections of the concrete tower work together effectively, jointly withstanding various external forces, such as wind loads and the unit's own weight. However, in actual operation, adhesive failure can occur due to various factors. For example, long-term exposure to complex environmental conditions, such as high temperature, high humidity, and strong ultraviolet radiation, can accelerate adhesive aging. Frequent vibration of wind turbines can also fatigue the adhesive, gradually degrading its bond performance. Furthermore, improper quality control during construction, such as unclean surface preparation and uneven adhesive thickness, can also lead to premature adhesive failure during use. Adhesive failure can seriously compromise the safe operation of wind turbines. It can cause gaps at tower joints, reducing the tower's overall stiffness and causing greater deformation and vibration under wind loads, impacting normal power generation and potentially leading to serious accidents such as tower collapse, resulting in significant economic losses and casualties. Several traditional reinforcement methods have been proposed to address adhesive failure, such as external steel plate wrapping and additional bolted connections. However, these methods often have limitations. For example, external steel plate wrapping requires a larger construction space, and the welding process can thermally impact the tower structure. Adding bolted connections can damage the concrete tower's original structure, and the tightening force of the bolts is difficult to uniformly control, easily leading to localized stress concentrations. Therefore, a more effective reinforcement method is needed to solve the problem of adhesive failure at the connection of the concrete tower of the hybrid wind turbine, so as to improve the safety and reliability of the wind turbine. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the above-mentioned shortcomings by providing a composite reinforcement method for failed adhesive at the connection between the towers of hybrid wind turbines. This composite reinforcement method improves the strength and fatigue life of the connection between the upper and lower concrete towers, reducing operation and maintenance costs. It is particularly suitable for repairing hybrid towers in high-humidity and high-salt-fog environments at sea, combining structural safety with intelligent management advantages.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0005] A composite reinforcement method for failed adhesive at the connection of a tower of a hybrid wind turbine generator system comprises the following steps:

[0006] Step 1: Determine the severity of the defects at the concrete tower connection based on the length, width, and depth of the adhesive failure at the connection between the upper and lower concrete towers of the hybrid wind turbine. Determine the reinforcement scheme using prestressed carbon fiber cloth based on the severity of the defects.

[0007] Step 2: Use an ultrasonic flaw detector to locate the debonding area, remove the failed colloid and polish the substrate surface to form a reinforcement area;

[0008] Step 3: A U-shaped groove is opened along the bonding seam, and a modified epoxy resin colloid containing chopped carbon fiber and nano-silica toughening agent is injected under high pressure. After thermal curing, an embedded repair layer is formed in the reinforced area;

[0009] Step 4: Apply epoxy resin glue to the outside of the embedded repair layer, then alternately lay horizontal carbon fiber cloth and vertical prestressed carbon fiber cloth on the outside of the embedded repair layer, install prestressed anchors on the tower concrete surface, prestress the vertical prestressed carbon fiber cloth with the prestressed anchors, and use vacuum-assisted resin infusion technology to bond the carbon fiber cloth to form a composite constraint layer;

[0010] Step 5: Pre-embed a fiber Bragg grating sensor in the composite constraint layer, connect the fiber Bragg grating sensor to the intelligent monitoring module, and apply a polyurea elastomer protective layer on the surface of the outermost prestressed carbon fiber cloth and the surface of the prestressed anchor. The intelligent monitoring module monitors the deformation of the carbon fiber cloth in real time based on the fiber Bragg grating sensor, thereby evaluating the reinforcement effect and the prestressed state of the prestressed carbon fiber cloth.

[0011] Step 6: Install a split-type annular steel hoop on the outside of the connection between the upper and lower concrete tower tubes, and apply radial pre-tightening force to the split-type annular steel hoop so that the split-type annular steel hoop hugs the composite constraint layer.

[0012] To optimize the above technical solutions, specific measures taken also include:

[0013] In step 1, the specific reinforcement scheme of prestressed carbon fiber cloth is as follows: for the failed adhesive at the connection between the upper and lower concrete tower tubes, two layers of horizontally arranged carbon fiber cloth are used to cover the damaged area for reinforcement, and multiple prestressed carbon fiber cloths are arranged vertically to reinforce the damaged area. The carbon fiber cloth is arranged in the following manner: two horizontal carbon fiber cloths and vertical prestressed carbon fiber cloths are arranged alternately from the inside to the outside.

[0014] The thickness of a single layer of carbon fiber cloth is 0.2-0.3mm, and its tensile strength is ≥4000MPa. No prestress is applied to the horizontally arranged carbon fiber cloth, while prestress is applied to the vertically arranged carbon fiber cloth. The length of the carbon fiber cloth is determined by the reinforcement scheme of the prestressed carbon fiber cloth: from inside to outside, the first layer of horizontally arranged carbon fiber cloth: the carbon fiber cloth is pasted along the direction of the concrete tower connection joint, and the width of the carbon fiber cloth exceeds the width of the connection joint by 150mm on both sides. The length of the carbon fiber cloth is adapted to the length of the failure of the adhesive at the tower connection; the second layer of vertically arranged prestressed carbon fiber cloth: multiple vertical prestressed carbon fiber cloths are pasted on the first layer of horizontal fiber cloth in a dense manner, with a spacing of 200mm between the vertical prestressed carbon fiber cloths. The number of vertical prestressed carbon fiber cloths is determined according to the failure length of the adhesive, and the length of the vertical prestressed carbon fiber cloth exceeds 330mm on both sides of the concrete tower connection joint; the third layer of horizontally arranged carbon fiber cloth: the same as the first layer of horizontal carbon fiber cloth, adopts the reinforcement method of horizontal overall covering, and the covering height is the same as the first layer of horizontal carbon fiber cloth.

[0015] In step 3, the tensile strength of the modified epoxy resin colloid is ≥60 MPa, the elongation is ≥8%, the amount of nano-silica added is 3%-5% of the total mass of the colloid; the depth of the U-shaped groove is 10-20 mm, and the width is 15-25 mm.

[0016] The thermal curing conditions of step 3 are: stepwise heating to 60-80°C, holding time ≥ 4 hours, and heating rate ≤ 5°C / min.

[0017] In step 4, the prestressed anchor is a wedge-shaped anchor with an anchor ring and a wedge-shaped clip. The wall thickness of the anchor ring is ≥10mm, the clamping force is ≥50kN, the slip amount is ≤0.05mm, the length of the wedge-shaped anchor is the length of the carbon fiber cloth plus 20mm, the width is 40mm, and the wedge angle is 12°.

[0018] In step 4, in the vacuum-assisted resin infusion process, the resin curing temperature is 60-80° C., the vacuum degree is ≤-0.09 MPa, and the fiber volume content is ≥60%.

[0019] In step 5, the fiber Bragg grating sensor is arranged in the middle of the bottom transverse carbon fiber cloth with a length of 100 mm, centered on the joint between the upper and lower towers, and 50 mm on each side.

[0020] In step 6, the material of the split-type annular steel hoop is Q345D steel, the radial preload design value is 150-250 kN / m, and the number of petals of the steel hoop is 2.

[0021] The inner surface of the split-type annular steel hoop is provided with a rubber buffer layer with a rubber hardness of 60-80 Shore A.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Compared with the technology of reinforcing the flat surface of concrete structure with carbon fiber cloth, the present invention breaks through the single technical bottleneck of traditional reinforcement methods in detection, materials, processes, monitoring and other links. First, the bonding scheme is determined according to the severity of the failure of the adhesive at the connection between the upper and lower concrete towers, and then the adhesive and base surface are pre-treated. Treating the tower connection seam into a U-shaped mouth can improve the bonding between the epoxy resin glue and the concrete at the crack; the carbon fiber cloth is pasted orthogonally, and prestress is applied to the vertical carbon fiber cloth to improve the reinforcement effect of the carbon fiber cloth; while pasting the first layer of horizontal carbon fiber cloth, the fiber optic Bragg grating sensor is pasted to monitor the prestress application and reinforcement effect in real time; the outer layer is sprayed with a polyurea elastomer protective layer to further prevent the carbon fiber cloth from falling off, and a split-type annular steel hoop is installed on the outermost side, and radial prestressing force is applied by a hydraulic tensioning device to further improve the defect reinforcement effect. On the other hand, the invention realizes the application of prestress to the large curved carbon fiber cloth by means of a wedge-shaped anchor sheet and an anchor ring, thereby improving the reinforcement effect of the carbon fiber cloth. The application and anchoring of prestressed carbon fiber cloth fundamentally ensures the effectiveness of reinforcing adhesive failure at the joints of the curved concrete tower reinforced with carbon fiber cloth. This significantly improves the safety, reliability, and service life of the concrete tower joints in hybrid wind turbines, providing significant engineering application value and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine generator set according to the present invention;

[0025] Figure 2 Schematic diagram of adhesive failure at the tower connection;

[0026] Figure 3 Post a schematic diagram of the solution for carbon fiber cloth;

[0027] Figure 4 This is a schematic diagram of the expansion treatment of the concrete tower connection;

[0028] Figure 5 Schematic diagram of attaching fiber Bragg grating sensor to the middle area of carbon fiber cloth with epoxy resin glue;

[0029] Figure 6 This is the layout diagram of the vertical carbon fiber cloth prestressed anchor;

[0030] Figure 7 Schematic diagram of a fixed wedge anchor for applying prestress;

[0031] Figure 8 This is a cross-sectional view of the tower connection reinforcement area;

[0032] Figure 9 It is a schematic diagram of a split-type annular steel hoop;

[0033] Figure 10 This is a schematic diagram of the installation of a split-type annular steel hoop. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts are within the scope of protection of this application.

[0035] Obviously, the drawings described below are merely examples or embodiments of the present application. Those skilled in the art can, without inventive effort, apply the present application to other similar scenarios based on these drawings. Furthermore, it is also understood that, although the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, changes in design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as an insufficiency of the content disclosed in this application.

[0036] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments unless there is a conflict.

[0037] Unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by a person of ordinary skill in the technical field to which this application belongs. The terms "a", "an", "a", "the" and the like used in this application do not indicate a limit on quantity and may indicate the singular or plural. The terms "include", "comprise", "have" and any variations thereof used in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The terms "connect", "connected", "coupled" and the like used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "multiple" / "several" used in this application refer to two or more. "And / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, or B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific order for the objects.

[0038] The embodiment of the present invention provides a composite reinforcement method for the failed adhesive at the connection of the tower of a mixed tower wind turbine. Figure 1 As shown in the figure, the repair method includes determining the reinforcement plan according to the severity of the adhesive failure, surface pretreatment, construction of the embedded repair layer, construction of the external constraint layer, embedding of the fiber grating sensor, installation of the mechanical reinforcement layer, and reinforcement quality inspection.

[0039] The reinforcement method includes the following steps:

[0040] Step 1: Determine the reinforcement plan for failed adhesive at the concrete tower joint

[0041] According to the failure length, width and depth of the adhesive at the connection between the upper concrete tower and the lower concrete tower of the hybrid wind turbine, the severity of the defect at the concrete tower connection is determined, and the corresponding prestressed carbon fiber cloth reinforcement solution is selected according to the severity of the defect;

[0042] Step 2: Failure area diagnosis and pretreatment

[0043] Use an ultrasonic flaw detector to locate the debonding area, remove the failed colloid and polish the substrate surface to a roughness of Ra ≥ 50μm to form a reinforcement area;

[0044] Step 3: Construction of embedded repair layer

[0045] A U-shaped groove is opened along the bonding seam, and a modified epoxy resin colloid containing chopped carbon fiber and nano-silica toughening agent is injected under high pressure, and then thermally cured to form an embedded repair layer;

[0046] Step 4: External Constraint Layer Construction

[0047] Horizontal carbon fiber cloth and vertical prestressed carbon fiber cloth are alternately laid on the outer wall of the tower. Epoxy resin glue is applied to the carbon fiber cloth bonding area. Prestressed anchors are installed on the tower concrete surface according to the prestressed carbon fiber cloth reinforcement plan. A vacuum-assisted resin infusion process is used to form the composite constraint layer.

[0048] Step 5: Monitoring system deployment

[0049] Fiber Bragg grating sensors are embedded in the reinforcement layer and connected to the intelligent monitoring module. A polyurea elastomer protective layer is coated on the surface of the prestressed carbon fiber cloth and the prestressed anchor. The intelligent monitoring module monitors the deformation of the prestressed carbon fiber cloth in real time based on the fiber Bragg grating sensors, thereby evaluating the reinforcement effect and the prestressed state of the prestressed carbon fiber cloth.

[0050] Step 6: Mechanical reinforcement layer installation

[0051] Split annular steel hoops are installed on the outside of the upper and lower concrete tower connection flanges, radial preload is applied through a hydraulic tensioning device, and the bolt torque is calibrated to the design value.

[0052] The embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0053] First, determine the area and range that needs to be reinforced based on the adhesive test results at the connection between the upper and lower concrete towers, and then determine the length of the adhesive failure. Figure 2 As shown, determine the carbon fiber cloth pasting scheme, the pasting scheme is as follows Figure 3 As shown, the horizontally arranged carbon fiber sheet is not prestressed, while the vertically arranged carbon fiber sheet is prestressed. The length of the carbon fiber sheet is determined by the prestressed carbon fiber sheet reinforcement scheme: ① The first layer of horizontally arranged carbon fiber sheet is affixed along the direction of the concrete tower joint. The carbon fiber sheet width exceeds the joint width by 150mm on both sides. The length of the carbon fiber sheet is adapted to the length of the adhesive failure at the tower joint. ② The second layer of vertically arranged prestressed carbon fiber sheet is affixed to the first layer of horizontal carbon fiber sheet in a dense pattern. The vertical prestressed carbon fiber sheet is spaced 200mm apart. The number of vertical prestressed carbon fiber sheet is determined based on the adhesive failure length. The length of the vertical prestressed carbon fiber sheet exceeds 330mm on both sides of the concrete tower joint. ③ The third layer of horizontally arranged carbon fiber sheet is the same as the first layer of horizontal carbon fiber sheet, adopting a horizontal overall wrapping reinforcement method. The wrapping height is the same as the first layer of horizontal carbon fiber sheet.

[0054] With the tower joint as the center, use a small cutting machine to expand the crack on both sides to form a U-shaped opening. Figure 4 As shown; clean the concrete surface within a certain range on both sides of the concrete tower connection joint to remove surface dust, oil, loose concrete and other impurities, then use a grinding tool to grind the concrete base along both sides of the joint until fresh aggregate is exposed, making it flat and rough, so as to enhance the bonding strength between the carbon fiber cloth and the concrete, and finally clean the surface with a high-pressure water gun and dry it in the sun until it is completely dry.

[0055] Use epoxy resin glue to stick the fiber Bragg grating sensor in the middle area of the carbon fiber cloth. Figure 5 The fiber Bragg grating sensor is arranged in the middle of the bottom prestressed carbon fiber cloth with a length of 100 mm, centered on the vertical crack and 50 mm on each side.

[0056] Before bonding, the carbon fiber cloth is pretreated and a suitable sizing agent is applied to its surface. The fiber Bragg grating sensor is placed in the center of the carbon fiber cloth and firmly bonded using nano-modified epoxy resin adhesive. The carbon fiber cloth and fiber Bragg grating sensor are sizing adhesive with a modified epoxy resin adhesive with a viscosity of 2500-3000 mPa·s and a shear strength of at least 15 MPa after curing. The bond strength loss is required to be no more than 5% at -40 degrees Celsius. The epoxy resin adhesive layer is 2.0-2.5 mm thick.

[0057] Install prestressed fixed wedge anchors on the tower surface, such as Figure 6 The wedge anchor is a steel structure, which consists of an anchor ring and a wedge clip. The wall thickness of the anchor ring is ≥10mm, the clamping force is ≥50kN, and the slippage is ≤0.05mm. After 2 million cycles of load testing, the wedge anchor has no cracks or slippage. Figure 7 As shown. The wedge clip length is the carbon fiber cloth width + 20mm, resulting in a width of 40mm and a wedge angle of 12°. For solutions requiring multiple layers of prestressed carbon fiber cloth, anchors are placed in one set per layer, with the bottom layer positioned on the outermost side of the crack and the top layer on the innermost side. Before attaching the anchors, the concrete surface is polished and cleaned. The adhesive used is a nano-modified epoxy resin adhesive with a viscosity of 3000-3500mPa·s and a shear strength of no less than 20Mpa. The adhesive layer thickness is 2.0-2.5mm, and the bond strength loss rate at -40 degrees Celsius does not exceed 5%.

[0058] Lightly brush the surface with a clean, small brush to remove dust. Repair the failed adhesive areas using pressure grouting at a pressure of 0.3-0.6 MPa. Use epoxy resin to fill the cracks and wedges. Then, apply epoxy resin to the carbon fiber sheeting attachment area with a brush. After curing, the epoxy resin should have a shear strength of no less than 15 MPa. The adhesive should cure in 4 hours or less at 20°C.

[0059] The pasting area is coated with epoxy resin glue, and then another clean brush is used to dip the epoxy resin glue and apply it to the pasting surface. The coating thickness of the bottom glue layer is 2.0-2.5mm, and the thickness of the middle layer is 1.5-2.0mm.

[0060] Use tensioning equipment to tension the vertical prestressed carbon fiber cloth, and slowly apply prestress of 5%-10% of the ultimate tensile strength with the tensioning equipment. Stop tensioning after reaching the preset value, inject nano-level modified epoxy resin glue into the gap, stick the carbon fiber cloth to the tower surface, and then anchor it.

[0061] Paste the first layer of transverse carbon fiber cloth.

[0062] Then the second layer of vertical prestressed carbon fiber cloth is tensioned, pasted and anchored.

[0063] Then, a third layer of transverse carbon fiber cloth is pasted.

[0064] The bonding quality of carbon fiber cloth and concrete is checked by ultrasonic testing instrument. The bubble area shall not exceed 1% of the bonding area. At the same time, the prestress loss of prestressed carbon fiber cloth shall not exceed 5% after 4 hours of bonding.

[0065] Coat the surface of carbon fiber cloth and prestressed wedge anchor with polyurea elastomer protective layer. The thickness of polyurea elastomer protective coating is 1.5-2.0mm, and the weather resistance grade is not lower than ASTM G154 standard. Tensile strength ≥25MPa, elongation ≥400%, tear strength ≥50MPa, no peeling or cracking when bent at -40 degrees, surface drying time less than 120s, water absorption ≤5%, such as Figure 8 shown.

[0066] After completing the above steps, install the mechanical reinforcement layer. Figure 9 The split-type annular steel hoop shown is installed in the repair area. The material of the split-type annular steel hoop is Q345D steel. The radial preload design value is 150-250kN / m. The number of petals of the steel hoop is 2. An independent hydraulic tensioning device is set. The inner surface of the split-type annular steel hoop is provided with a rubber buffer layer with a rubber hardness of 60-80 Shore A. The installation of the split-type annular steel hoop is shown in the figure. Figure 10 shown.

[0067] The fiber grating (FBG) sensor is connected to an intelligent monitoring module, which uses the FBG sensor to monitor the deformation of the prestressed carbon fiber sheet in real time, thereby assessing the reinforcement effect and the prestressed state of the prestressed carbon fiber sheet. The intelligent monitoring module performs in-depth analysis and calculations on the data transmitted by the FBG sensor. It accurately calculates the actual stress on the carbon fiber sheet and compares it with the initial prestress value, clearly demonstrating the degree of deviation in the prestressed state of the prestressed carbon fiber sheet. Through this method, the FBG sensor enables a detailed assessment of the effectiveness of carbon fiber sheet repairs on concrete throughout its entire lifecycle, providing comprehensive safety assurance for wind turbine hybrid towers.

[0068] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the described embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A composite reinforcement method for failed adhesive at the connection of a tower of a mixed-tower wind turbine, characterized in that: The following steps are involved: Step 1: Determine the severity of the defects at the concrete tower connection based on the length, width, and depth of the adhesive failure at the connection between the upper and lower concrete towers of the hybrid wind turbine. Determine the reinforcement scheme using prestressed carbon fiber cloth based on the severity of the defects. Step 2: Use an ultrasonic flaw detector to locate the debonding area, remove the failed colloid and polish the substrate surface to form a reinforcement area; Step 3: A U-shaped groove is opened along the bonding seam, and a modified epoxy resin colloid containing chopped carbon fiber and nano-silica toughening agent is injected under high pressure. After thermal curing, an embedded repair layer is formed in the reinforced area; Step 4: Apply epoxy resin glue to the outside of the embedded repair layer, then alternately lay horizontal carbon fiber cloth and vertical prestressed carbon fiber cloth on the outside of the embedded repair layer, install prestressed anchors on the tower concrete surface, prestress the vertical prestressed carbon fiber cloth with the prestressed anchors, and use vacuum-assisted resin infusion technology to bond the carbon fiber cloth to form a composite constraint layer; Step 5: Pre-embed a fiber Bragg grating sensor in the composite constraint layer, connect the fiber Bragg grating sensor to the intelligent monitoring module, and apply a polyurea elastomer protective layer on the surface of the outermost prestressed carbon fiber cloth and the surface of the prestressed anchor. The intelligent monitoring module monitors the deformation of the carbon fiber cloth in real time based on the fiber Bragg grating sensor, thereby evaluating the reinforcement effect and the prestressed state of the prestressed carbon fiber cloth. Step 6: Install a split-type annular steel hoop on the outside of the connection between the upper and lower concrete tower tubes, and apply radial pre-tightening force to the split-type annular steel hoop so that the split-type annular steel hoop hugs the composite constraint layer.

2. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1 is characterized in that: In step 1, the specific reinforcement scheme of prestressed carbon fiber cloth is as follows: for the failed adhesive at the connection between the upper and lower concrete tower tubes, two layers of horizontally arranged carbon fiber cloth are used to cover the damaged area for reinforcement, and multiple prestressed carbon fiber cloths are arranged vertically to reinforce the damaged area. The carbon fiber cloth is arranged in the following manner: two horizontal carbon fiber cloths and vertical prestressed carbon fiber cloths are arranged alternately from the inside to the outside.

3. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 2 is characterized in that: The thickness of a single layer of carbon fiber cloth is 0.2-0.3mm, and its tensile strength is ≥4000MPa. No prestress is applied to the horizontally arranged carbon fiber cloth, while prestress is applied to the vertically arranged carbon fiber cloth. The length of the carbon fiber cloth is determined by the reinforcement scheme of the prestressed carbon fiber cloth: from inside to outside, the first layer of horizontally arranged carbon fiber cloth: the carbon fiber cloth is pasted along the direction of the concrete tower connection joint, and the width of the carbon fiber cloth exceeds the width of the connection joint by 150mm on both sides. The length of the carbon fiber cloth is adapted to the length of the failure of the adhesive at the tower connection; the second layer of vertically arranged prestressed carbon fiber cloth: multiple vertical prestressed carbon fiber cloths are pasted on the first layer of horizontal fiber cloth in a dense manner, with a spacing of 200mm between the vertical prestressed carbon fiber cloths. The number of vertical prestressed carbon fiber cloths is determined according to the failure length of the adhesive, and the length of the vertical prestressed carbon fiber cloth exceeds 330mm on both sides of the concrete tower connection joint; the third layer of horizontally arranged carbon fiber cloth: the same as the first layer of horizontal carbon fiber cloth, adopts the reinforcement method of horizontal overall covering, and the covering height is the same as the first layer of horizontal carbon fiber cloth.

4. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1 is characterized in that: In step 3, the tensile strength of the modified epoxy resin colloid is ≥60MPa, the elongation is ≥8%, and the amount of nano-silica added is 3%-5% of the total mass of the colloid; the depth of the U-shaped groove is 10-20mm and the width is 15-25mm.

5. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1 is characterized in that: The thermal curing conditions of step 3 are: stepwise heating to 60-80°C, holding time ≥ 4 hours, and heating rate ≤ 5°C / min.

6. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1 is characterized in that: In step 4, the prestressed anchor is a wedge-shaped anchor having an anchor ring and a wedge-shaped clip, the anchor ring wall thickness is ≥10mm, the clamping force is ≥50kN, the slip amount is ≤0.05mm, the length of the wedge-shaped anchor is the length of the carbon fiber cloth plus 20mm, the width is 40mm, and the wedge angle is 12°.

7. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1 is characterized in that: In step 4, in the vacuum-assisted resin infusion process, the resin curing temperature is 60-80° C., the vacuum degree is ≤-0.09 MPa, and the fiber volume content is ≥60%.

8. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1, characterized in that: In step 5, the fiber Bragg grating sensor is arranged in the middle of the bottom transverse carbon fiber cloth, with a length of 100 mm, centered on the connection seam between the upper and lower towers, and 50 mm on each side.

9. The composite reinforcement method for failed adhesive at the connection of the tower of a hybrid wind turbine according to claim 1, characterized in that: In step 6, the material of the split-type annular steel hoop is Q345D steel, the radial preload design value is 150-250 kN / m, and the number of petals of the steel hoop is 2.

10. A composite reinforcement method for failed adhesive at the connection of a tower of a hybrid wind turbine according to claim 9, characterized in that: The inner surface of the split-type annular steel hoop is provided with a rubber buffer layer, and the rubber hardness is 60-80 Shore A.

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