Method for reinforcing vertical cracks of tower drum concrete of mixed tower wind turbine generator

Abstract

The invention discloses a tower drum concrete vertical crack reinforcing method for a mixed tower wind turbine generator, which comprises the following steps of: firstly, determining a pasting scheme according to the severity of the crack, then carrying out a crack and base surface treatment step, and treating the vertical crack into a wedge opening shape so as to improve the bonding between epoxy resin glue and concrete at the crack; the carbon fiber cloth is pasted in an orthogonal mode, prestress is applied to the transverse carbon fiber cloth, and the reinforcing effect of the carbon fiber cloth is improved; meanwhile, a fiber grating sensor is pasted to monitor prestress applying and reinforcing effects in real time; a polyurea elastomer protective layer is sprayed on the outermost layer, so that the carbon fiber cloth is further prevented from falling off. According to the method, the reinforcing effect of the carbon fiber cloth is improved, classification treatment of the wind power concrete according to the development severity of the vertical cracks, treatment of the cracks and the concrete surface and application and anchoring of prestress of the carbon fiber cloth are achieved, and the reinforcing effect of reinforcing the vertical cracks of the curved surface concrete of the wind power tower tube through the carbon fiber cloth is fundamentally guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural reinforcement of wind power generation equipment, and relates to a method for reinforcing vertical cracks in the tower barrel concrete of a hybrid tower wind turbine. The present invention is particularly applicable to the repair and bearing capacity improvement of tower barrel cracks in an environment of high dynamic loads and large temperature differences. Background Art

[0002] Concrete wind power tower barrels are a type of tower barrel that has emerged in recent years. Due to their large stiffness and low cost compared to all-steel tower barrels, they have quickly occupied more than half of the tower barrels over 140 meters as soon as they appeared. However, some problems have also occurred during construction and application. When prestressing cables are applied to concrete tower barrels, uneven cable forces cause excessive local concrete compression and vertical cracks. Wind power tower barrels generate vertical cracks under the bending moment generated by wind loads during long-term operation. If not reinforced, it will affect the service life of the wind turbine, and in severe cases, it may collapse. Traditional carbon fiber reinforcement methods are mainly used for reinforcing planar structures, and existing technologies mostly use single carbon fiber cloth pasting, which has problems such as insufficient interfacial bonding force, failure to consider stress redistribution under dynamic loads, easy secondary cracking, poor control of reinforcement quality, and poor fatigue performance.

[0003] For vertical cracks in the large curved surface structure of tower barrel concrete, the traditional process uses single-layer horizontal pasting. After the carbon fiber cloth is infiltrated with epoxy resin glue and cured, it is prone to peeling due to curvature mismatch. Existing processes have problems such as being unable to apply prestress to the carbon fiber cloth pasted on the large curved surface, and the prestress cannot be controlled in real time, and the prestressed carbon fiber cloth cannot be anchored. They also do not integrate an intelligent monitoring module and cannot evaluate the reinforcement effect in real time.

[0004] Therefore, the above technical problems need to be further solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for reinforcing vertical cracks in the tower barrel concrete of a hybrid tower wind turbine in view of the above existing deficiencies. To achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0006] A method for reinforcing vertical cracks in the tower barrel concrete of a hybrid tower wind turbine, comprising the following steps:

[0007] Step 1: Determine the severity of the vertical crack defect in the tower barrel concrete of the hybrid tower wind turbine according to the cracking length, width, and depth of the vertical crack, and select a corresponding prestressed carbon fiber cloth reinforcement plan according to the severity of the vertical crack;

[0008] Step 2: Carry out grooving treatment on the vertical crack to form a wedge opening, and drill holes at the end of the vertical crack to release stress concentration; use a grinding tool to grind the concrete base surface on both sides of the vertical crack until fresh aggregate is exposed to form a reinforcement and strengthening area;

[0009] Step 3: Cut the carbon fiber cloth to make its size fit the reinforcement and strengthening area, and paste the fiber Bragg grating sensor in the middle area of the carbon fiber cloth with epoxy resin glue;

[0010] Step 4: Install prestressed anchors on the surface of the tower barrel concrete according to the prestressed carbon fiber cloth reinforcement and strengthening plan;

[0011] Step 5: Adopt the pressure grouting method to repair the vertical crack of the tower barrel concrete in a reinforcing manner, and apply epoxy resin glue to the area where the carbon fiber cloth is pasted;

[0012] Step 6: Apply prestress to the carbon fiber cloth and then horizontally anchor it to both ends of the length of the vertical crack of the tower barrel concrete. The prestressed carbon fiber cloth is fixed to the reinforcement and strengthening area through epoxy resin glue;

[0013] Step 7: Connect the fiber Bragg grating sensor to the intelligent monitoring module, and apply a polyurea elastomer protective layer on the surface of the prestressed carbon fiber cloth and the surface of the prestressed anchor. The intelligent monitoring module real-time monitors the deformation of the prestressed carbon fiber cloth according to the fiber Bragg grating sensor, so as to evaluate the reinforcement effect and the prestress state of the prestressed carbon fiber cloth.

[0014] To optimize the above technical solution, the specific measures taken also include:

[0015] In Step 1, the prestressed carbon fiber cloth reinforcement and strengthening plan is specifically as follows: for the vertical cracks in the wind turbine tower barrel concrete with a small development, a single-layer horizontal arrangement of prestressed carbon fiber cloth is used for reinforcement and strengthening; for the vertical cracks in the wind turbine tower barrel concrete with a moderate development, a two-horizontal and one-vertical arrangement of carbon fiber cloth is used for reinforcement and strengthening, that is, two horizontal carbon fiber cloths and one vertical carbon fiber cloth are alternately arranged from bottom to top; for the vertical cracks in the wind turbine tower barrel concrete with a large development, a three-horizontal and two-vertical arrangement of carbon fiber cloth is used for reinforcement and strengthening, that is, three horizontal carbon fiber cloths and two vertical carbon fiber cloths are alternately arranged from bottom to top.

[0016] The small development of the vertical crack in the wind turbine tower barrel concrete specifically means: the length of the vertical crack is less than the height of one section of the concrete tower barrel, and at the same time the crack depth is less than the wall thickness of the concrete tower barrel; the moderate development of the vertical crack in the wind turbine tower barrel concrete specifically means: the crack depth has penetrated the concrete wall thickness, but the crack width is less than 0.2 mm and the crack length has not penetrated the entire height of the tower barrel in the concrete height direction; the large development of the vertical crack in the wind turbine tower barrel concrete specifically means: the crack depth has penetrated the concrete wall thickness, the crack length has penetrated the entire height of the tower barrel in the concrete height direction, or the crack width is greater than 0.2 mm.

[0017] The single-layer thickness of the carbon fiber cloth is 0.2 - 0.3 mm, and the tensile strength is ≥ 3500 MPa. Prestress is applied to the horizontally arranged carbon fiber cloth, while no prestress is applied to the vertically arranged carbon fiber cloth. The length of the carbon fiber cloth is determined by the prestressed carbon fiber cloth reinforcement and strengthening plan: ① Single-layer horizontal arrangement of prestressed carbon fiber cloth reinforcement plan: Paste the prestressed carbon fiber cloth along the horizontal direction of the vertical crack. The length of the prestressed carbon fiber cloth exceeds 150 mm on each side of the crack width. For multiple cracks, not less than 150 mm on each side of the outermost crack, plus 40 mm inside each of the two prestressed anchors and 50 mm outside each of the prestressed anchors, that is, 240 mm on each side centered on the crack; ② Two-horizontal and one-vertical arrangement of carbon fiber cloth plan: If a single crack is reinforced, the length of the bottom-layer horizontal carbon fiber cloth exceeds 330 mm on each side of the crack width, the length of the upper-layer horizontal carbon fiber cloth is 240 mm on each side centered on the crack, and the length of the vertical carbon fiber cloth is adapted to the length of the crack. ③ Three-horizontal and two-vertical arrangement of carbon fiber cloth plan: The length of the bottom-layer horizontal carbon fiber cloth exceeds 420 mm on each side of the crack width, the length of the middle-layer horizontal carbon fiber cloth exceeds 330 mm on each side of the crack width, the length of the top-layer horizontal carbon fiber cloth exceeds 240 mm on each side of the crack width, and the length of the vertical carbon fiber cloth runs through the entire section of the tower barrel.

[0018] In step 2, the specific steps for expanding the vertical crack are as follows: Cut a V-shaped groove along the crack direction, with a groove depth of 10 - 15 mm and a groove top width of 20 - 30 mm; Drill stress relief holes with a diameter of 8 - 12 mm and a depth of 50 - 80 mm; Clean and polish the concrete surface of the tower barrel on both sides of the crack. The polishing range is 150 mm on each side from the crack center. If there are multiple cracks, the polishing range is the distance between 150 mm outside the center of the outermost cracks on both sides, with a height of 20 mm outside the crack height and a polishing depth of 2 - 4 mm or exposing fresh aggregate.

[0019] In step 3, the fiber Bragg grating sensor is arranged in the middle part of the bottom-layer horizontal carbon fiber cloth, with a length of 100 mm, centered on the vertical crack, 50 mm on each side.

[0020] In step 4, the prestressed anchor is a wedge-shaped anchor with an anchor ring and wedge-shaped clamping pieces. The wall thickness of the anchor ring is ≥ 10 mm, the clamping force is ≥ 50 kN, the slip is ≤ 0.05 mm. The length of the wedge-shaped anchor is 20 mm plus the length of the carbon fiber cloth, the width is 40 mm, and the wedge angle is 12°.

[0021] In step 5, the grouting material used in the pressure grouting method is epoxy resin. After the epoxy resin glue cures, the shear strength is not less than 15 MPa. The curing time of the adhesive at 20 °C is less than or equal to 4 hours. Pressure grouting is carried out using a grouting machine, and the grouting pressure is 0.5 - 0.6 MPa.

[0022] In Step 6, a prestress of 5%-10% of the ultimate tensile strength is applied to the carbon fiber cloth by an electric tensioner, and then anchoring is carried out. For the multi-layer pasting scheme, the bottom-layer horizontal carbon fiber cloth passes through the anchor rings of the middle layer and the upper layer of the anchor, and the middle-layer carbon fiber cloth passes through the anchor ring of the upper-layer carbon fiber cloth. The construction sequence is to first carry out the tensioning and anchoring of the bottom layer, then the middle layer, and finally the upper layer. After the prestressed carbon fiber cloth is pasted and fixed to the reinforcement area with epoxy resin glue for 4 hours, the prestress of the prestressed carbon fiber cloth is compared with that during tensioning, and the loss does not exceed 5%.

[0023] In Step 7, the thickness of the urea elastomer protective coating is 1.5 - 2.0 mm, the tensile strength ≥ 25 MPa, and the water absorption rate ≤ 5%.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] Compared with the technology of strengthening the flat surface of a concrete structure with carbon fiber cloth, on the one hand, the present invention provides a method for strengthening carbon fiber cloth for vertical cracks on the large-curved surface of concrete. First, determine the pasting scheme according to the severity of the cracks, and then carry out the steps of crack and base surface treatment. Treating the vertical cracks into a wedge shape can improve the adhesion of the epoxy resin glue to the concrete at the crack; the carbon fiber cloth is pasted in an orthogonal manner, and prestress is applied to the horizontal carbon fiber cloth to improve the strengthening effect of the carbon fiber cloth; at the same time, fiber Bragg grating sensors are pasted to monitor the prestress application and strengthening effect in real time; the outermost layer is sprayed with a polyurea elastomer protective layer to further prevent the carbon fiber cloth from falling off. On the other hand, the present invention realizes the application of prestress to the carbon fiber cloth on the large-curved surface through the wedge-shaped anchor piece and the anchor ring, thereby improving the strengthening effect of the carbon fiber cloth. The present invention realizes the classification treatment of wind power concrete according to the severity of the development of vertical cracks, treats the cracks and the concrete surface, applies and anchors the prestress of the carbon fiber cloth, and fundamentally ensures the strengthening effect of the carbon fiber cloth for strengthening the vertical cracks on the curved surface of the wind power tower barrel. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the method for strengthening the vertical cracks of the tower barrel concrete of the mixed tower wind turbine unit of the present invention;

[0027] Figure 2 It is a schematic diagram of the vertical crack defect of the tower barrel concrete;

[0028] Figure 3 It is a schematic diagram of the treatment of the crack depth expansion joint of the tower barrel concrete;

[0029] Figure 4 It is a schematic diagram of the single-layer horizontal layout prestressed carbon fiber cloth strengthening scheme;

[0030] Figure 5 It is a schematic diagram of the carbon fiber cloth layout scheme in the two-horizontal and one-vertical mode;

[0031] Figure 6 Schematic diagram of the carbon fiber cloth arranged in a three-horizontal and two-vertical manner;

[0032] Figure 7 Structural diagram of the horizontal carbon fiber cloth;

[0033] Figure 8 Structural diagram of the vertical carbon fiber cloth;

[0034] Figure 9 Schematic diagram of pasting fiber Bragg grating sensors with epoxy resin glue in the middle area of the carbon fiber cloth;

[0035] Figure 10 Schematic diagram of the prestressed anchor;

[0036] Figure 11 Layout diagram of the prestressed anchor in the prestressed carbon fiber cloth reinforcement scheme with a single-layer horizontal arrangement;

[0037] Figure 12 Layout diagram of the prestressed anchor in the carbon fiber cloth arrangement scheme with two-horizontal and one-vertical manner;

[0038] Figure 13 Layout diagram of the prestressed anchor in the carbon fiber cloth arrangement scheme with a three-horizontal and two-vertical manner;

[0039] Figure 14 Cross-sectional view of the concrete reinforcement area of the tower barrel. Detailed implementation manners

[0040] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be described and explained below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0041] Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without making creative efforts, the present application can also be applied to other similar scenarios based on these drawings. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0042] References to "embodiments" in this application mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0043] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the ordinary meaning understood by those with ordinary skills in the technical field to which this application pertains. The words "a", "one", "kind", "the", and the like involved in this application do not indicate a limitation in quantity and can represent a singular or plural number. The terms "include", "comprise", "have" and any variations thereof involved in this application are intended to cover non-exclusive inclusion; 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 further include unlisted steps or units, or may further include other steps or units inherent to these processes, methods, products, or devices. The terms "connect", "be connected", "couple" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. 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.

[0044] An embodiment of the present invention provides a method for reinforcing vertical cracks in the concrete of the tower barrel of a hybrid tower wind turbine, as Figure 1 shown. The repair method includes determining a pasting scheme according to the severity of the cracks, crack and surface treatment, determining the size of the carbon fiber, pasting the carbon fiber wedge-shaped anchor, applying epoxy resin glue, tensioning and anchoring the prestressed carbon fiber cloth, a protection treatment step, an effect evaluation step, etc.

[0045] The following further describes the embodiments of the present invention in detail with reference to the accompanying drawings.

[0046] First, determine the crack area and scope that need to be strengthened according to the concrete crack detection results, and then according to the height, width, and depth of the cracks, as Figure 2As shown in the figure, determine the carbon fiber cloth pasting scheme, which ranges from single-layer horizontal prestressed carbon fiber cloth reinforcement to the three-horizontal and two-vertical pasting reinforcement scheme: When the crack length is less than the height of one section of the concrete tower barrel and the crack depth is less than the wall thickness of the concrete tower barrel, the single-layer horizontal prestressed cloth reinforcement scheme is adopted for vertical cracks; for cracks with a depth that has penetrated the concrete wall thickness but a crack width less than 0.2 mm (the crack width at the center of the outermost layer of steel bars), the two-horizontal and one-vertical pasting method is adopted, that is, two layers of prestressed carbon fiber cloth are pasted perpendicular to the crack direction, and one layer of non-prestressed carbon fiber cloth is pasted along the crack propagation direction. For cracks with a large crack width, a crack depth that has penetrated the concrete wall thickness, a length that penetrates the entire height of one section in the concrete height direction, or a crack width greater than 0.2 mm, the three-horizontal and two-vertical pasting scheme is adopted, that is, three layers of prestressed carbon fiber cloth are pasted perpendicular to the crack propagation direction, and non-prestressed carbon fiber cloth is pasted along the crack development direction.

[0047] Centering on the vertical crack, use a small cutting machine to widen the crack on both sides to form a wedge-shaped opening as Figure 3 shown, and drill holes at the crack ends to release stress concentration; clean the concrete surface of the vertical crack and within a certain range on both sides of the crack to remove surface dust, oil stains, loose concrete and other impurities, and then use a grinding tool to grind the concrete base surface on both sides of the crack until fresh aggregate is exposed, making it flat and rough to enhance the bonding force between the carbon fiber cloth and the concrete. Finally, clean the surface with a high-pressure water gun and dry it completely.

[0048] Cut the carbon fiber cloth as Figures 4 - 8 shown: According to the length and width of the vertical crack, accurately cut the carbon fiber cloth so that its size fits the reinforcement area. Determination of the carbon fiber cloth length: ① Single-layer horizontal reinforcement scheme, as Figure 4 shown: If reinforcing a single vertical crack, the carbon fiber cloth length exceeds 150 mm on both sides of the vertical crack width. For reinforcing multiple cracks, the outermost cracks should have no less than 150 mm on both sides, plus 40 mm inside each of the two side anchors and 50 mm outside each wedge-shaped anchor, that is, 240 mm on both sides centered on the crack. ② Two-horizontal and one-vertical scheme, as Figure 5 shown: If reinforcing a single crack, the length of the bottom layer carbon fiber cloth exceeds 240 mm + 40 mm + 50 mm = 330 mm on both sides of the crack width, the length of the upper layer is 240 mm on both sides centered on the crack, and the vertical length remains unchanged. ③ Three-horizontal and two-vertical scheme, as Figure 6 shown: The length of the bottom layer carbon fiber cloth exceeds 240 mm + (40 mm + 50 mm) * 2 = 420 mm on both sides of the crack width, the length of the middle layer carbon fiber cloth exceeds 240 mm + 40 mm + 50 mm = 330 mm on both sides of the crack width, the length of the top layer prestressed carbon fiber cloth exceeds 240 mm on both sides of the crack width, and the vertical non-prestressed carbon fiber cloth runs through the height of the tower barrel.

[0049] Paste the fiber Bragg grating sensor in the middle area of the carbon fiber cloth with epoxy resin glue. As Figure 9 shown, the fiber Bragg grating sensor is arranged in the middle part of the bottom prestressed carbon fiber cloth with a length of 100 mm. Centered on the vertical crack, 50 mm on each side. If the crack length is large, multiple carbon fiber cloths need to be arranged side by side vertically.

[0050] Before pasting, first pre-treat the carbon fiber cloth and apply a suitable sizing agent on its surface. The fiber Bragg grating sensor is arranged on the middle carbon fiber cloth and is firmly pasted with nano-modified epoxy resin glue. The sizing agent for the carbon fiber cloth and the fiber Bragg grating sensor is nano-modified epoxy resin glue, with a viscosity of 2500 - 3000 mPa·s, and the shear strength after curing is not less than 15 MPa. It is required that the bond strength loss rate does not exceed 5% in an environment of -40 °C, and the thickness of the epoxy resin glue layer is 2.0 - 2.5 mm.

[0051] Install the prestress application fixed wedge-shaped anchor on the surface of the tower barrel, as Figure 10 shown. The wedge-shaped anchor is made of steel structure and is divided into an anchor ring and wedge-shaped clamping pieces. The wall thickness of the anchor ring is ≥10 mm, the clamping force is ≥50 kN, the slip amount is ≤0.05 mm, and through 2 million cycle load tests, there are no cracks and no slips in the wedge-shaped anchor. The length of the wedge-shaped clamping piece is the width of the carbon fiber cloth + 20 mm, the width is 40 mm, and the wedge angle is 12°. For the scheme of pasting multiple layers of prestressed carbon fiber cloth, one set of anchors is used for each layer. The bottom layer is on the outermost side of the crack, and the top layer is on the innermost side. Before pasting the anchor, the concrete surface is polished and cleaned in the same way as in step 2. The pasting glue is nano-modified epoxy resin glue, with a viscosity of 3000 - 3500 mPa·s and a shear strength of not less than 20 Mpa. The thickness of the glue layer is 2.0 - 2.5 mm, and the bond strength loss rate does not exceed 5% in an environment of -40 °C. For the single-layer horizontal prestress pasting scheme, as Figure 11 arrange the anchors on both sides of the carbon fiber cloth. The two-horizontal and one-vertical pasting scheme is as Figure 12 shown, and for the three-horizontal and two-vertical pasting scheme, the anchor arrangement is as Figure 13 shown. Note that the installation of the anchor should be perpendicular to the horizontal prestressed carbon fiber cloth.

[0052] Use a clean small brush to thinly brush the surface, aiming to remove the surface dust once again. Adopt the pressure grouting method to repair the vertical crack, and the grouting pressure is 0.3 - 0.6 MPa. The repair slurry is epoxy resin glue, ensuring that the crack voids and the inside of the wedge are filled. Then use a brush to apply epoxy resin glue in the pasting area of the carbon fiber cloth. The shear strength of the epoxy resin glue after curing is not less than 15 MPa, and the curing time of the adhesive is less than or equal to 4 hours at 20 °C.

[0053] Epoxy resin glue is applied to the pasting area, and then another clean brush is used to dip fully in the epoxy resin glue and apply it to the pasting surface. The coating thickness of the bottom layer glue layer is 2.0 - 2.5 mm, and the thickness of the middle layer is 1.5 - 2.0 mm.

[0054] Tensioning equipment is used to tension the carbon fiber cloth with transverse prestress. For the three - horizontal - two - vertical pasting and reinforcement scheme, first, one side of the bottom - layer carbon fiber cloth passes through three anchor rings on the same side and extends 50 mm outside the outermost anchor ring. One side of it is fixed by inserting a wedge into the anchor ring. Then, the tensioning equipment is used to slowly apply prestress of 5% - 10% of the ultimate tensile strength. After reaching the preset value, the tensioning stops. Nano - level modified epoxy resin glue is injected into the gap, and the carbon fiber cloth is pasted on the surface of the tower barrel, and then anchoring is carried out.

[0055] Paste the first - layer vertical carbon fiber cloth.

[0056] Then tension the second - layer carbon fiber cloth with transverse prestress, paste it, and anchor it.

[0057] Further paste the second - layer vertical carbon fiber cloth.

[0058] Then construct the third - layer carbon fiber cloth with transverse prestress.

[0059] An ultrasonic detector is used to detect the bonding quality between the carbon fiber cloth and the concrete. The area of air bubbles shall not exceed 1% of the pasting area; at the same time, the prestress loss of the prestressed carbon fiber cloth within 4 hours after pasting shall not exceed 5%.

[0060] A polyurea elastomer protective layer is coated on the surface of the carbon fiber cloth and the surface of the prestressed wedge - shaped anchor. The thickness of the polyurea elastomer protective coating is 1.5 - 2.0 mm, and the weather resistance grade is not lower than the ASTM G154 standard. Tensile strength ≥ 25 MPa, elongation at break ≥ 400%, tear strength ≥ 50 MPa, no peeling or cracking at - 40 degrees bending, surface drying time less than 120 s, water absorption rate ≤ 5%, as Figure 14 shown.

[0061] An intelligent monitoring module is connected to the fiber Bragg grating sensor. The intelligent monitoring module monitors the strain change of the prestressed carbon fiber cloth in real - time according to the fiber Bragg grating sensor, thereby determining the state of crack development, and further evaluating the reinforcement effect and the prestress state of the prestressed carbon fiber cloth. Through the above - mentioned method, the fiber Bragg grating sensor can realize the refined evaluation of the whole - life cycle of the effect of carbon fiber cloth in repairing concrete, providing "from details to the whole" safety guarantee for the wind - power hybrid tower.

[0062] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine, characterized in that: The following steps are involved: Step 1: According to the length, width and depth of the vertical cracks in the tower concrete of the mixed tower wind turbine unit, determine the severity of the vertical crack defects in the concrete, and select the corresponding prestressed carbon fiber cloth reinforcement scheme according to the severity of the vertical cracks; Step 2: Expand the vertical cracks to form wedges, and drill holes at the ends of the vertical cracks to release stress concentration; use a grinding tool to grind the concrete base along both sides of the vertical cracks until fresh aggregate is exposed to form a reinforcement area; Step 3: Cut the carbon fiber cloth to make its size fit the reinforcement area, and glue the fiber Bragg grating sensor to the middle area of ​​the carbon fiber cloth with epoxy resin glue; Step 4: Install prestressed anchors on the tower concrete surface according to the prestressed carbon fiber cloth reinforcement scheme; Step 5: Use the pressure grouting method to reinforce the vertical cracks in the tower concrete and apply epoxy resin glue to the carbon fiber cloth pasting area; Step 6: After applying prestress to the carbon fiber cloth, it is laterally anchored to both ends of the vertical crack length of the tower concrete. The prestressed carbon fiber cloth is fixed to the reinforcement area by epoxy resin glue; Step 7: Connect the fiber grating sensor to the intelligent monitoring module, and coat the surface of the prestressed carbon fiber cloth and the prestressed anchor with a polyurea elastomer protective layer. The intelligent monitoring module monitors the deformation of the prestressed carbon fiber cloth in real time based on the fiber grating sensor, thereby evaluating the reinforcement effect and the prestressed state of the prestressed carbon fiber cloth.

2. A method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, characterized in that: In step 1, the prestressed carbon fiber cloth reinforcement scheme is specifically as follows: for wind turbine tower concrete with smaller vertical cracks, a single layer of transversely arranged prestressed carbon fiber cloth is used for reinforcement; for wind turbine tower concrete with moderate vertical cracks, the carbon fiber cloth is arranged in a two-horizontal and one-vertical manner for reinforcement, that is, two transverse carbon fiber cloths and one vertical carbon fiber cloth are arranged alternately from bottom to top; for wind turbine tower concrete with larger vertical cracks, the carbon fiber cloth is arranged in a three-horizontal and two-vertical manner for reinforcement, that is, three transverse carbon fiber cloths and two vertical carbon fiber cloths are arranged alternately from bottom to top.

3. A method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 2, characterized in that: The vertical cracks in the concrete of wind turbine tower are small in scope, which means: the length of the vertical cracks is less than the height of one section of the concrete tower, and the depth of the cracks is less than the wall thickness of the concrete tower; the vertical cracks in the concrete of wind turbine tower are moderate in scope, which means: the depth of the vertical cracks has penetrated the concrete wall thickness, but the crack width is less than 0.2mm, and the length of the cracks has not penetrated the entire height of the tower section in the direction of the concrete height; the vertical cracks in the concrete of wind turbine tower are large in scope, which means: the depth of the vertical cracks has penetrated the concrete wall thickness, the length of the cracks has penetrated the entire height of the tower section in the direction of the concrete height, or the crack width is greater than 0.2mm.

4. A method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 3, characterized in that: The single-layer thickness of carbon fiber cloth is 0.2-0.3mm, and the tensile strength is ≥3500MPa. The transversely arranged carbon fiber cloth is prestressed, and the vertically arranged carbon fiber cloth is not prestressed. The length of the carbon fiber cloth is determined by the prestressed carbon fiber cloth reinforcement reinforcement plan: ① Single-layer transverse prestressed carbon fiber cloth reinforcement plan: Paste prestressed carbon fiber cloth along the transverse direction of the vertical crack. The length of the prestressed carbon fiber cloth exceeds the crack width by 150mm on both sides. If multiple cracks are reinforced, the outermost crack is not less than 150mm on both sides, plus 40mm inside the prestressed anchor on both sides, and 50mm outside the prestressed anchor, that is, the crack is the center. 240mm on each side; ② Two horizontal and one vertical carbon fiber cloth arrangement plan: If a single crack is reinforced, the length of the bottom horizontal carbon fiber cloth exceeds the crack width by 330mm on both sides, the length of the upper horizontal carbon fiber cloth is 240mm on both sides of the center of the crack, and the length of the vertical carbon fiber cloth is adapted to the length of the crack; ③ Three horizontal and two vertical carbon fiber cloth arrangement plan: the length of the bottom horizontal carbon fiber cloth exceeds the crack width by 420mm on both sides, the length of the middle horizontal carbon fiber cloth exceeds the crack width by 330mm on both sides, the length of the top horizontal carbon fiber cloth exceeds the crack width by 240mm on both sides, and the length of the vertical carbon fiber cloth runs through the entire section of the tower.

5. The method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, characterized in that: In step 2, the specific steps for expanding the vertical cracks are as follows: dig a V-shaped groove along the direction of the crack, with a groove depth of 10-15mm and a groove top width of 20-30mm; drill a stress relief hole with a diameter of 8-12mm and a depth of 50-80mm; clean and polish the tower concrete surface on both sides of the crack, and the polishing range is 150mm on both sides from the center of the crack. If there are multiple cracks, the polishing range is the distance between 150mm outside the center of the uppermost crack on both sides, and the height is 20mm outside the crack height. The polishing depth is 2-4mm or fresh aggregate is exposed.

6. A method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, characterized in that: In step 3, the fiber grating sensor is arranged in the middle of the bottom transverse carbon fiber cloth, with a length of 100 mm, centered on the vertical crack and 50 mm on both sides.

7. A method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, 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°.

8. The method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, characterized in that: In step 5, the grouting material used in the pressure grouting method is epoxy resin. The shear strength of the epoxy resin glue after curing is not less than 15MPa. The adhesive curing time is less than or equal to 4 hours at 20°C. A grouting machine is used for pressure grouting, and the grouting pressure is 0.5-0.6MPa.

9. The method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, characterized in that: In step 6, a prestress of 5%-10% of the ultimate tensile strength is applied to the carbon fiber cloth by an electric tensioner, and then anchored. For the multi-layer pasting scheme, the bottom transverse carbon fiber cloth passes through the anchor rings of the middle layer and the upper anchor, and the middle layer carbon fiber cloth passes through the anchor ring of the upper carbon fiber cloth. The construction sequence is to tension and anchor the bottom layer first, then the middle layer, and finally the upper layer. The prestressed carbon fiber cloth is pasted and fixed to the reinforced area by epoxy resin glue for 4 hours. The prestress of the prestressed carbon fiber cloth is compared with the prestress during tensioning, and the loss does not exceed 5%.

10. The method for reinforcing vertical cracks in tower concrete of a mixed tower wind turbine according to claim 1, characterized in that: In step 7, the urea elastomer protective coating has a thickness of 1.5-2.0 mm, a tensile strength of ≥25 MPa, and a water absorption rate of ≤5%.

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