A method for repairing large-area fracture of a secondary grouting layer of a fan foundation

Abstract

The application discloses a method for repairing large-area broken secondary grouting layer of a fan foundation, belongs to the technical field of foundation reinforcement of wind turbine generators, and aims at solving the problems of long repair period, high repair cost and repeated diseases after repair of the large-area broken secondary grouting layer of the fan. After the secondary grouting layer of the area to be repaired is removed, the roughened part of the foundation platform for laying the grouting material is leveled, a steel beam section is horizontally embedded between the foundation platform and the upper annular anchor plate, the embedded steel beam section is anchored on the foundation platform through prestressed anchor rods, the symmetric installation mode is adopted, the remaining steel beam sections are repeatedly embedded, and the steel beam sections form a closed annular steel beam until the annular steel beam is formed. A waterproof rubber strip is arranged between the top of the annular steel beam and the upper annular anchor plate, post-poured grouting material is poured in the annular steel beam, and curing is performed until the design strength is reached, and the fan anchor bolt group is pre-tightened. The method can repair the broken secondary grouting layer without removing the fan, and greatly shortens the repair period.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine foundation reinforcement technology, and particularly relates to a repair method for large-area breakage of the secondary grouting layer of a wind turbine foundation. Background Technology

[0002] Wind energy, as a renewable and clean energy source, has broad application prospects. In recent years, with the development of wind power technology, onshore and offshore wind energy have been widely developed and applied. Wind turbines are key equipment for wind energy utilization, and with stable operation and mature manufacturing technology, wind turbines have been widely put into use.

[0003] As a crucial supporting component for wind turbines, the wind turbine foundation is essential for ensuring their normal operation. Within the foundation, the secondary grouting layer is a critical structural layer connecting the bottom flange of the tower (via foundation rings / anchor plates) to the concrete foundation. Its role is paramount, directly impacting the long-term safety, stability, and durability of the wind turbine. However, with the increasing service life of the wind turbine foundation, and due to prolonged exposure to alternating loads or design and construction issues, problems such as large-scale cracking and breakage of the secondary grouting layer can occur. Damage to the secondary grouting layer leads to load transfer failure between the tower and the foundation, causing issues like foundation ring swaying, grout leakage, and tower anchor bolt failure, seriously threatening the safe operation of the wind turbine.

[0004] Traditional methods for treating secondary grouting layer defects in wind turbine foundations mainly include "filling repair" and "local reinforcement." These methods are primarily used to repair situations where the secondary grouting layer is not densely poured, has micro-cracks, or is locally crushed. However, they cannot prevent the further expansion of the defects. Currently, the repair method for crushed secondary grouting layers in wind turbine foundations typically involves dismantling the wind turbine, removing the broken secondary grouting layer, re-pouring the grouting layer, and then reinstalling the wind turbine. While this method is safe, it is time-consuming and results in significant economic losses. Summary of the Invention

[0005] The purpose of this invention is to provide a repair method for large-area breakage of the secondary grouting layer in wind turbine foundations, thereby solving the problems of long repair cycles, high repair costs, and easy recurrence of damage after repair when large areas of the secondary grouting layer is crushed. The technical solution adopted by this invention is as follows:

[0006] A method for repairing large-area damage to the secondary grouting layer of a wind turbine foundation, wherein the wind turbine is a wind turbine generator, and the wind turbine foundation includes a foundation platform, an upper annular anchor plate, and a bottom flange of the wind turbine. The lower parts of several wind turbine anchor bolt assemblies are respectively anchored to the foundation platform. The annular bottom flange of the wind turbine and the upper annular anchor plate are coaxially abutting each other. Several first flange hole groups are provided on the circumference of the bottom flange of the wind turbine, and several second flange hole groups are provided on the circumference of the upper annular anchor plate. The several first flange hole groups and several second flange hole groups are connected one-to-one with the upper parts of several wind turbine anchor bolt assemblies. The tower of the wind turbine is fixed on the bottom flange of the wind turbine. The secondary grouting layer is formed by concrete poured between the foundation platform and the upper annular anchor plate. The repair method includes the following steps:

[0007] Step 1: Prefabricate steel beam segments. Each steel beam segment includes an upper and lower plate in a fan-shaped ring. The upper and lower plates have the same outer contour and are aligned vertically. They are connected by several supporting stiffeners. The supporting stiffeners are machined with mud flow holes. The lower plate has several fixed lugs on its large-diameter arc side, and the fixed lugs are equipped with anchor bolt holes. The two straight sides of the upper plate and the two straight sides of the lower plate are connected by connecting plates. The connecting plates are machined with assembly hole groups. Several vertically and horizontally permeable clearance grooves are machined radially upward from the small-diameter side of the steel beam segment. When several steel beam segments are circumferentially assembled to form a ring steel beam, the clearance grooves of the ring steel beam correspond one-to-one with the first flange hole groups of the bottom flange of the wind turbine. The wall thickness of the supporting stiffeners, connecting plates, upper plate, and lower plate is determined based on the wind turbine load calculation. The large-diameter side radius and small-diameter side radius of the steel beam segment are consistent with the secondary grouting layer.

[0008] Step 2: Divide the secondary grouting layer into several fan-shaped segments according to the central angle of the steel beam segment, and select any one of the fan-shaped segments as the area to be repaired;

[0009] Step 3: Unload all wind turbine anchor bolts in the area to be repaired in sections until they are completely loose, and monitor the verticality of the wind turbine tower throughout the process;

[0010] Step 4: Remove the secondary grouting layer in the area to be repaired, roughen the exposed foundation surface, clean the roughened part of the foundation, and then lay the bedding grout to level the roughened part of the foundation surface.

[0011] Step 5: Horizontally embed a steel beam segment between the foundation cap and the upper annular anchor plate in the area to be repaired, so that the upper end face of the steel beam segment is consistent with the secondary grouting layer, and so that several wind turbine anchor bolt groups in the area to be repaired are inserted into several clearance grooves of the steel beam segment one by one.

[0012] Step 6: Based on the positions of several anchor holes already embedded in the steel beam segment, drill several anchor holes on the foundation platform;

[0013] Step 7: Insert prestressed anchor rods into the anchor holes and pour high-strength grout. After the grout reaches solidification strength, pull out several prestressed anchor rods one by one and connect the tops of several prestressed anchor rods to several anchor holes one by one.

[0014] Step 8: Pre-tighten each wind turbine anchor bolt group in the area to be repaired to 50% of the design pre-tightening force;

[0015] Step 9: Using a symmetrical installation method, repeat steps 3 to 8, and install and fix several steel beam segments one by one as the remaining fan ring segments as the repair area until the several steel beam segments form a closed ring steel beam, and the ring steel beam is coaxial with the wind turbine tower.

[0016] Step 10: All assembly holes of any two adjacent steel beam segments are tightened laterally with high-strength bolts;

[0017] Step 11: Install a waterproof strip between the top of the annular steel beam and the upper annular anchor plate;

[0018] Step 12: After filling the interior of the ring-shaped steel beam, pour grout and cure it to the design strength;

[0019] Step 13: Tighten each wind turbine anchor bolt group to 100% of the design preload.

[0020] Furthermore, the steel beam segments are made of steel with a yield strength lower limit greater than or equal to 345 MPa.

[0021] Furthermore, in step four, the surface flatness error of the foundation platform where the mortar is laid for leveling is ≤ ±3mm / m.

[0022] Furthermore, grouting holes and venting holes are set when pouring grout after injection, and the grout is poured using pressure injection.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This invention replaces the bearing function of the original broken secondary grouting layer with a ring-shaped steel beam, fundamentally solving the problem of repeated crushing of the secondary grouting layer due to insufficient strength or stress concentration, ensuring the permanence and structural integrity of the repair. Simultaneously, the steel beam segments connected by high-strength bolts form a high-circumferential-stiffness whole, which, combined with the strong anchoring provided by prestressed anchor rods deeply embedded in the foundation abutment, significantly improves the integrity, stiffness, and load-bearing capacity of the repaired structure, effectively transferring wind turbine loads and greatly enhancing the foundation's pull-out, shear, and overturning resistance.

[0025] 2. Regarding construction safety, the construction sequence of "segmented removal, intermittent support, and symmetrical installation" was adopted, and a graded controllable load transfer strategy of "complete unloading → pre-tightening to 50% of the design value → final pre-tightening to 100% of the design value" was implemented for the wind turbine anchor bolt group. This was supplemented by monitoring the verticality of the wind turbine tower throughout the process, which maximized the stability of the wind turbine and construction safety during the repair process. The broken secondary grouting layer could be repaired without dismantling the wind turbine, which greatly shortened the repair period.

[0026] 3. Regarding the reliability of the repair interface, this invention strictly requires the surface of the foundation abutment to be finely roughened and cleaned, the grout to be laid to ensure uniform contact, and the selection of post-cast grout with high fluidity, micro-expansion, early strength, high strength and durability, supplemented by waterproof strips on the top of the ring steel beam and suggested joint sealing measures, to construct multiple protections, effectively ensuring the bonding strength and long-term durability of the interface and preventing water seepage and erosion.

[0027] 4. Modular steel beam segments can be prefabricated, and early-strength materials are used for the standardization and strict monitoring of key processes, which effectively optimizes construction efficiency and ensures the overall repair quality. Attached Figure Description

[0028] Figure 1 This is an exploded view of the wind turbine foundation after the repair according to the present invention;

[0029] Figure 2 It is a ring-shaped steel beam;

[0030] Figure 3 This is a structural schematic diagram of the steel beam segment;

[0031] Figure 4 This is a schematic diagram of the assembly of two steel beam segments;

[0032] Figure 5 This is a schematic diagram of a ring-shaped steel beam fixed to a foundation cap;

[0033] Figure 6 This is a schematic diagram of grouting after the interior of the ring-shaped steel beam has been filled.

[0034] In the diagram, 1. Foundation cap, 2. Upper annular anchor plate, 21. Second flange hole group, 3. Wind turbine bottom flange, 31. First flange hole group, 4. Wind turbine anchor bolt group, 5. Annular steel beam, 51. Steel beam segment, 52. Upper plate, 53. Lower plate, 54. Support stiffener plate, 55. Connecting plate, 56. Fixed lug, 57. Assembly hole group, 58. Anchor bolt hole, 59. High-strength bolt, 510. Circumvention groove, 6. Post-pouring grout, 7. Prestressed anchor bolt, 8. High-strength grout. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0036] The connections mentioned in this invention are divided into fixed connections and detachable connections. Fixed connections, also known as non-detachable connections, include but are not limited to conventional fixed connection methods such as folded connections, riveted connections, adhesive connections, and welded connections. Detachable connections include but are not limited to conventional disassembly methods such as bolted connections, snap-fit ​​connections, pin connections, and hinged connections. When a specific connection method is not explicitly defined, it is assumed that at least one existing connection method can be found to achieve this function, and those skilled in the art can choose according to their needs. For example, a welded connection can be chosen for fixed connections, and a bolted connection can be chosen for detachable connections.

[0037] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0038] Example: Figures 1-6 As shown, a method for repairing large-area damage to the secondary grouting layer of a wind turbine foundation is disclosed. The wind turbine is a wind turbine generator. The wind turbine foundation includes a foundation platform 1, an upper annular anchor plate 2, and a bottom flange 3. The lower parts of several wind turbine anchor bolt groups 4 are anchored to the foundation platform 1. The several wind turbine anchor bolt groups 4 are evenly arranged circumferentially. Each group of wind turbine anchor bolt groups 4 consists of two anchor bolts arranged radially. The annular bottom flange 3 and the upper annular anchor plate 2 are coaxially abutted vertically. Several first flange hole groups 31 are provided on the circumference of the bottom flange 3. Each group of first flange holes 31... A flange hole group 31 consists of two radially arranged flange holes. Several second flange hole groups 21 are circumferentially arranged on the upper annular anchor plate 2. Each second flange hole group 21 consists of two radially arranged flange holes. Several first flange hole groups 31 and several second flange hole groups 21 are connected one-to-one with the upper parts of several wind turbine anchor bolt groups 4. The wind turbine tower is fixed to the bottom flange 3 of the wind turbine. The secondary grouting layer is formed by concrete poured between the foundation cap 1 and the upper annular anchor plate 2. The repair method includes the following steps:

[0039] Step 1: Precast steel beam segment 51. Steel beam segment 51 includes a fan-shaped annular upper plate 52 and a lower plate 53. The outer contours of the upper plate 52 and lower plate 53 are identical, and the upper plate 52 and lower plate 53 are aligned vertically and connected by several supporting stiffeners 54. The supporting stiffeners 54 are machined with slurry flow holes. The large-diameter arc-shaped side of the lower plate 53 is provided with several fixing lugs 56, and the fixing lugs 56 are provided with anchor bolt holes 58. The two straight sides of the upper plate 52 and the two straight sides of the lower plate 53 are connected by connecting plates 55. Assembly hole group 57 is machined on the steel beam segment 51. Several vertically and vertically transparent clearance grooves 510 are machined radially upward from the small diameter side of the steel beam segment 51. When several steel beam segments 51 are circumferentially assembled to form a ring steel beam 5, the clearance grooves 510 of the ring steel beam 5 correspond one-to-one with the first flange hole group 31 of the bottom flange 3 of the fan. The wall thickness of the support stiffener 54, connecting plate 55, upper plate 52 and lower plate 53 is determined according to the fan load calculation. The large diameter side radius and small diameter side radius of the steel beam segment 51 are consistent with the secondary grouting layer.

[0040] Step 2: Divide the secondary grouting layer into several fan-shaped segments according to the central angle of the steel beam segment 51, and select any one of the fan-shaped segments as the area to be repaired;

[0041] Step 3: Unload all wind turbine anchor bolt groups 4 in sections until they are completely loose, and monitor the verticality of the wind turbine tower throughout the process.

[0042] Step 4: Remove the secondary grouting layer in the area to be repaired, roughen the surface of the exposed foundation 1, clean the roughened part of the foundation 1, and then lay the bedding grout to level the roughened part of the foundation 1.

[0043] Step 5: Horizontally embed the steel beam segment 51 between the foundation platform 1 and the upper annular anchor plate 2 in the area to be repaired, so that the upper end face of the steel beam segment 51 is consistent with the secondary grouting layer, and so that the several wind turbine anchor bolt groups 4 in the area to be repaired are inserted into the several clearance grooves 510 of the steel beam segment 51 one by one.

[0044] Step 6: Based on the positions of several anchor holes 58 already embedded in the steel beam segment 51, drill several anchor holes on the foundation cap 1.

[0045] Step 7: Insert prestressed anchor rods 7 into the anchoring holes and pour high-strength grout 8. After the grout reaches solidification strength, pull out several prestressed anchor rods 7 one by one and connect the top of several prestressed anchor rods 7 to several anchor rod holes 58 one by one.

[0046] Step 8: Pre-tighten each wind turbine anchor bolt group 4 in the area to be repaired to 50% of the design pre-tightening force;

[0047] Step 9: Using a symmetrical installation method, repeat steps 3 to 8, and sequentially treat the remaining fan ring segments as the areas to be repaired to ensure uniform installation stress of the annular steel beam 5. Install and fix several steel beam segments 51 one by one until several steel beam segments 51 form a closed annular steel beam 5, and the annular steel beam 5 is coaxial with the wind turbine tower.

[0048] Step 10: The assembly hole groups 57 of any two adjacent steel beam segments 51 are all tightened laterally by high-strength bolts 59.

[0049] Step 11: Install a waterproof strip between the top of the annular steel beam 5 and the upper annular anchor plate 2;

[0050] Step 12: After filling the interior of the ring steel beam 5, pour grout 6 and cure it to the design strength;

[0051] Step 13: Tighten each of the wind turbine anchor bolt groups 4 to 100% of the design preload.

[0052] Steel beam segment 51 is made of steel with a lower yield strength of 345 MPa or greater.

[0053] In step four, the surface flatness error of the foundation pier 1, which is leveled by laying the mortar, is ≤±3mm / m to ensure that the bottom of the steel beam is evenly stressed.

[0054] When pouring grout 6 after grouting, grouting holes and vent holes are set, and grout 6 is poured by pressure grouting.

[0055] The waterproof sealing strip is an elastic sealing material that can completely fill the gap between the top of the annular steel beam 5 and the upper annular anchor plate 2. The post-cast grout 6 has high fluidity, micro-expansion, early strength and durability. The arrangement of several prestressed anchor rods 7 corresponds one-to-one with several wind turbine anchor bolt groups 4, and the length of the anchor rods penetrating into the foundation pedestal 1 meets the effective anchoring requirements.

[0056] 1. This invention replaces the bearing function of the original broken secondary grouting layer with a ring-shaped steel beam 5, fundamentally solving the problem of repeated crushing of the secondary grouting layer due to insufficient strength or stress concentration, ensuring the permanence and structural integrity of the repair. Simultaneously, the steel beam segments 51 connected by high-strength bolts 59 form a high-circumferential-stiffness whole, which, combined with the strong anchoring provided by the prestressed anchor rods 7 extending deep into the foundation abutment 1, significantly improves the integrity, stiffness, and bearing capacity of the repaired structure, effectively transferring wind turbine loads and greatly enhancing the foundation's pull-out, shear, and overturning resistance.

[0057] 2. Regarding construction safety, the construction sequence of "segmented removal, intermittent support, and symmetrical installation" was adopted, and a graded controllable load transfer strategy of "complete unloading → pre-tightening to 50% of the design value → final pre-tightening to 100% of the design value" was implemented for wind turbine anchor bolt group 4. This was supplemented by monitoring the verticality of the wind turbine tower throughout the process, which maximized the stability of the wind turbine and construction safety during the repair process. The broken secondary grouting layer could be repaired without dismantling the wind turbine, which greatly shortened the repair period.

[0058] 3. Regarding the reliability of the repair interface, this invention strictly requires the surface of the foundation pier 1 to be finely roughened and cleaned, and the grout to be laid to ensure uniform contact. It also selects post-cast grout 6 with high fluidity, micro-expansion, early strength, high strength and durability, supplemented by waterproof strips on the top of the ring steel beam 5 and suggested joint sealing measures to construct multiple protections, effectively ensuring the bonding strength and long-term durability of the interface and preventing water seepage and erosion.

[0059] 4. Modular steel beam segments 51 can be prefabricated, and early-strength materials are used for the standardization and strict monitoring of key processes, which effectively optimizes construction efficiency and ensures the overall repair quality.

[0060] The above embodiments are merely illustrative examples of the present invention and do not limit its scope of protection. Those skilled in the art can make partial changes to them, as long as they do not exceed the spirit and essence of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A method for repairing large-area damage to the secondary grouting layer of a wind turbine foundation, wherein the wind turbine is a wind turbine generator, the wind turbine foundation includes a foundation pier (1), an upper annular anchor plate (2), and a wind turbine bottom flange (3), the lower parts of several wind turbine anchor bolt groups (4) are respectively anchored to the foundation pier (1), the annular wind turbine bottom flange (3) and the upper annular anchor plate (2) are coaxially abutting each other, several first flange hole groups (31) are provided on the upper circumference of the wind turbine bottom flange (3), several second flange hole groups (21) are provided on the upper circumference of the upper annular anchor plate (2), the several first flange hole groups (31) and several second flange hole groups (21) are all connected one-to-one with the upper parts of several wind turbine anchor bolt groups (4), the wind turbine tower is fixed on the wind turbine bottom flange (3), and the secondary grouting layer is formed by concrete poured between the foundation pier (1) and the upper annular anchor plate (2), characterized in that, The repair method includes the following steps: Step 1: Precast steel beam segment (51). The steel beam segment (51) includes an upper plate (52) and a lower plate (53) in a fan-shaped ring. The outer contours of the upper plate (52) and the lower plate (53) are the same. The upper plate (52) and the lower plate (53) are aligned vertically and connected by several supporting stiffeners (54). The supporting stiffeners (54) are machined with mud flow holes. The large-diameter arc side of the lower plate (53) is provided with several fixing lugs (56). The fixing lugs (56) are provided with anchor holes (58). The two straight sides of the upper plate (52) and the two straight sides of the lower plate (53) are connected by connecting plates (55). Assembly hole group (57) is machined on plate (55). Several through clearance grooves (510) are machined radially upward from the small diameter side of steel beam segment (51). When several steel beam segments (51) are circumferentially assembled to form a ring steel beam (5), several clearance grooves (510) of the ring steel beam (5) correspond one-to-one with several first flange hole groups (31) of the bottom flange (3) of the fan. The wall thickness of the support stiffener plate (54), connecting plate (55), upper plate (52) and lower plate (53) is determined according to the fan load calculation. The large diameter side radius and small diameter side radius of the steel beam segment (51) are consistent with the secondary grouting layer. Step 2: Divide the secondary grouting layer into several fan-shaped segments according to the central angle of the steel beam segment (51), and select any one of the fan-shaped segments as the area to be repaired; Step 3: Unload all wind turbine anchor bolt groups (4) in sections to the area to be repaired until they are completely relaxed, and monitor the verticality of the wind turbine tower throughout the process; Step 4: Remove the secondary grouting layer of the area to be repaired, roughen the surface of the exposed foundation (1), clean the roughened part of the foundation (1), and then lay the bedding grout to level the roughened part of the foundation (1). Step 5: Horizontally embed a steel beam segment (51) between the foundation platform (1) and the upper annular anchor plate (2) in the area to be repaired, so that the upper end face of the steel beam segment (51) is consistent with the secondary grouting layer, and so that a number of wind turbine anchor bolt groups (4) in the area to be repaired are inserted into a number of clearance grooves (510) of the steel beam segment (51) in a corresponding manner. Step 6: Based on the positions of several anchor holes (58) already embedded in the steel beam segment (51), drill several anchor holes on the foundation cap (1); Step 7: Insert prestressed anchor rods (7) into the anchor holes and pour high-strength grout (8). After the solidification strength is reached, pull out several prestressed anchor rods (7) one by one and connect the top of several prestressed anchor rods (7) to several anchor holes (58) one by one. Step 8: Pre-tighten each wind turbine anchor bolt group (4) in the area to be repaired to 50% of the design pre-tightening force; Step 9: Using a symmetrical installation method, repeat steps 3 to 8, and install and fix several steel beam segments (51) one by one as the remaining fan ring segments to be repaired, until several steel beam segments (51) form a closed ring steel beam (5), and the ring steel beam (5) is coaxial with the wind turbine tower. Step 10: The assembly hole groups (57) of any two adjacent steel beam segments (51) are all tightened laterally by high-strength bolts (59); Step 11: Install a waterproof strip between the top of the annular steel beam (5) and the upper annular anchor plate (2); Step 12: After grouting inside the ring steel beam (5), pour grout (6) and cure it to the design strength; Step 13: Tighten each wind turbine anchor bolt group (4) to 100% of the design pre-tightening force.

2. The method for repairing large-area fracture of the secondary grouting layer of a wind turbine foundation according to claim 1, characterized in that: The steel beam section (51) is made of steel with a yield strength lower limit greater than or equal to 345 MPa.

3. The method for repairing large-area fracture of the secondary grouting layer of a wind turbine foundation according to claim 1, characterized in that: In step four, the surface flatness error of the foundation platform (1) for laying the mortar and leveling is ≤ ±3mm / m.

4. The method for repairing large-area fracture of the secondary grouting layer of a wind turbine foundation according to claim 1, characterized in that: When pouring grout (6) after grouting, grouting holes and vent holes are set, and pressure grouting is used to pour grout (6).

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