Construction method for repairing duct grouting defect and improving compactness of bent section of box girder

Abstract

The invention is applicable to the technical field of bridge engineering construction, and provides a box girder bending section duct grouting defect repair and compactness improvement construction method, which comprises the following steps: detecting through a concrete multifunctional nondestructive detector and probing and positioning an uncompacted area of a duct through an endoscope; according to the defect degree, a graded repairing process is adopted; a drilling reinjection method is adopted for local cavities, and superfine cement paste or epoxy resin is injected; carrying out secondary grouting in a negative pressure environment by adopting a vacuum-assisted slurry supplementing process for integral defects; for serious defects, a slotting repair method is adopted, and micro-expansion mortar is filled after loose mortar is removed. By optimizing the slurry proportion, additionally arranging the exhaust holes and adopting the defect grouting repairing technology, the problem that grouting of the bent section pore channel is not compact is effectively solved, the compactness after repairing can reach 95% or above, and the durability and safety of the box girder structure are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering construction, and in particular to a construction method for repairing grouting defects in a bent section of a box girder and improving its density. Background Art

[0002] During the construction of prestressed box girders, the grouting in the curved section is prone to being loose due to the large curvature and poor ventilation. Traditional repair methods have problems such as inaccurate positioning and incomplete repair.

[0003] Therefore, in view of the above situation, there is an urgent need to provide a construction method for repairing the grouting defects and improving the density of the box girder curved section to overcome the shortcomings in current practical applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a construction method for repairing grouting defects in the curved section of a box girder and improving its density, so as to effectively solve the problems in the above-mentioned background technology.

[0005] The present invention is achieved by providing a construction method for repairing grouting defects in a bent section of a box beam and improving its density, the method comprising the following steps: Step (1) hole inspection and defect location: Use a multifunctional concrete non-destructive testing instrument and an endoscope to inspect the hole and determine the location and range of the non-compacted area; Step (2) defect classification and graded repair construction: the defects are divided into level I defects, level II defects and level III defects, where level I defects are local void defects, level II defects are overall defects, and level III defects are serious loose defects; a. For local void defects, use the drilling and filling method to inject ultra-fine cement slurry or epoxy resin; b. For integral defects, a vacuum-assisted grouting process is used. After sealing both ends of the duct, vacuum is drawn and then secondary grouting is performed. c. For serious non-compact defects, adopt the slotting repair method, remove the protective layer, remove the loose slurry, and fill with micro-expansion mortar; Step (3) Quality acceptance: After the repair is completed, the density is tested using the impact echo method.

[0006] As a further solution of the present invention: the ultrafine cement slurry in step (2) a is prepared with P·O42.5 cement, with a water-cement ratio of 0.3-0.35, and is added with 0.5%-1% UEA expansion agent, 12% silica fume and 0.2% water reducer, and the fluidity is ensured to be 12±1s and the initial setting time ≥4h through the stirring process.

[0007] As a further solution of the present invention: in step (2) a, a hydraulic drilling machine equipped with a diamond drill bit is used to drill φ20±1mm grouting holes perpendicular to the axis of the channel in the defective area, with a hole spacing of 40cm in the straight section and 30cm in the curved section, and an φ8mm exhaust hole is added to the top of the corrugated pipe; When installing the grouting system, a special grouting pipe with a check valve is implanted, and the gaps around the pipe are sealed with quick-hardening sealant.

[0008] As a further solution of the present invention: in step (2) a, an electric grouting pump is used to start grouting from the lowest hole, controlling the pressure to 0.6±0.05 MPa and the speed to 3-5 L / min, and after the adjacent hole is slurried, the grouting is switched to the next hole, and finally the grouting is completed from the highest exhaust hole and the pressure is maintained for 3 minutes; 24 hours after the grouting is completed, the exposed grouting pipe is removed, and the holes are sealed with M50 non-shrinkage mortar and wet-cured for 7 days. The pressure-time curve is recorded in real time during the construction process, so that the grouting volume of a single hole reaches 120-150% of the theoretical void volume, the distance between adjacent holes is ≥50cm, and the core strength at 28 days is ≥45MPa.

[0009] As a further solution of the present invention: before the groove repair method in step (2) b is performed, three-dimensional laser scanning is used to accurately locate the defective area, and a hydraulic cutting machine is used to cut a U-shaped groove along the direction of the channel, the groove being deep enough to completely expose the corrugated pipe, and a special cutter is used to neatly cut the corrugated pipe 15 cm away from the edge of the defect; The exposed prestressed steel bars are first sandblasted to remove rust, and then sprayed with a 1.2mm thick epoxy zinc-rich anti-corrosion coating.

[0010] As a further solution of the present invention: in the step (2) b, a threaded connection sleeve with a compressive strength of ≥50 MPa is used to connect the fracture, and a pre-tightening torque of 35 N·m is applied during installation.

[0011] As a further solution of the present invention: before the vacuum-assisted grouting process in step (2) c is carried out, an acoustic CT scan is used to determine the defect range, sealing covers are installed at both ends of the duct, and a vacuum pump system is connected via a φ20mm high-pressure hose; Start the vacuum pump and control the vacuum degree to above -0.08MPa and maintain it for 15 minutes, while keeping the channel temperature within the range of 15 to 30℃.

[0012] As a further solution of the present invention: in step (2) c, the grouting material is modified ultrafine cement slurry, the proportion of which is P·II 52.5 cement mixed with 20% mineral powder and 0.03% polycarboxylate water reducer, with a water-cement ratio of 0.30-0.32. After stirring in a mixer for 3 minutes, the grouting is injected at a pressure of 0.5-0.8 MPa, and the grouting speed is controlled at 4-6 L / min; During the grouting process, the changes in vacuum degree need to be monitored in real time. When slurry with consistent consistency overflows from the exhaust pipe, the vacuum state should be maintained for 10 minutes, and then the valve should be closed to maintain the pressure for 30 minutes. The sealing device should be removed after 24 hours.

[0013] As a further solution of the present invention: additional exhaust holes are provided at intervals of 3-5m in the bent section; For sharp bends with a curvature radius of less than 10m, 3 to 5 auxiliary exhaust valves must be added to the top, and a segmented stepped grouting process must be adopted; For sharp bends with a curvature radius R < 8m, the corrugated pipe local replacement process is adopted, and detachable inspection openings with a spacing of ≤ 3m are set.

[0014] As a further solution of the present invention: during construction in winter, antifreeze needs to be added to the slurry and insulation measures need to be taken to maintain the slurry temperature within the range of 10-25°C.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. High repair accuracy: Ultrasound-endoscope combined technology can control the defect positioning error within ±2cm; 2. Strong material adaptability: Ultra-fine cement slurry can penetrate into 0.1mm cracks, and epoxy resin is suitable for repairing active cracks; 3. Process reliability: The vacuum-assisted process increases the slurry filling degree by more than 40%, and the secondary defect rate is less than 3%; 4. Low overall cost: save 35%-50% of construction cost compared with the traditional full-line grooving method; The present invention is not only applicable to highway bridges, but can also be extended to prestressed concrete structures such as railway box girders and municipal elevated roads, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a construction flow chart of the present invention; Figure 2 This is a schematic diagram of the drilling and filling method in the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the vacuum-assisted grouting construction in the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the construction of the slot repair method of the present invention; Figure 5 This is a schematic diagram of the drilling and filling method in the present invention. Figure 2 ; Figure 6 This is a schematic diagram of the drilling and filling method in the present invention. Figure 3 ; Figure 7 This is a schematic diagram of the vacuum-assisted grouting construction in the present invention. Figure 2 ; Figure 8 This is a schematic diagram of the vacuum-assisted grouting construction in the present invention. Figure 3 .

[0018] In the attached figure: 1-check valve, 2-exhaust hole, 3-grouting hole, 4-special grouting pipe, 5-high-pressure hose, 6-sealing cover. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] The detection equipment used in the present invention is a multifunctional nondestructive testing instrument for concrete (model), and the grouting material is ultrafine cement slurry prepared with P·O42.5 cement.

[0021] The present invention will be further explained below with reference to specific embodiments.

[0022] See also Figures 1-8 The embodiment of the present invention provides a method for repairing defects in grouting holes in a bent section of a box beam and improving the compactness thereof, the method comprising the following steps: Step (1) hole inspection and defect location: Use a multifunctional concrete non-destructive testing instrument and an endoscope to inspect the hole and determine the location and range of the non-compacted area; Step (2) defect classification and graded repair construction: the defects are divided into level I defects, level II defects and level III defects, where level I defects are local void defects, level II defects are overall defects, and level III defects are serious loose defects; a. For local void defects, use the drilling and filling method to inject ultra-fine cement slurry or epoxy resin; b. For integral defects, a vacuum-assisted grouting process is used. After sealing both ends of the duct, vacuum is drawn and then secondary grouting is performed. c. For serious non-compact defects, adopt the slotting repair method, remove the protective layer, remove the loose slurry, and fill with micro-expansion mortar; Step (3) Quality acceptance: After the repair is completed, the density is tested using the impact echo method.

[0023] In this embodiment, this method has high repair accuracy: the combined ultrasound-endoscopic technology can control the defect positioning error within ±2cm; strong material adaptability: ultrafine cement slurry can penetrate into cracks as small as 0.1mm, and epoxy resin is suitable for repairing active cracks; process reliability: the vacuum-assisted process increases the slurry filling degree by more than 40%, and the secondary defect rate is less than 3%; and low overall cost: compared with the traditional full-line grooving method, the construction cost is saved by 35%-50%; The present invention is not only applicable to highway bridges, but can also be extended to prestressed concrete structures such as railway box girders and municipal elevated roads, and has significant economic and social benefits.

[0024] In one embodiment of the present invention, see Figures 1-8 Taking the repair of a bent section of a 40m span prestressed concrete box girder as an example, the specific implementation steps are as follows: Defect detection and positioning: A full-section scan of the tunnel using a multifunctional concrete nondestructive testing instrument revealed three loose areas at the top of the L / 4 span bend, with the largest cavity measuring 15cm x 8cm. During construction, precise positioning was achieved using a BIM model coordinate positioning system combined with a rebar scanner. A hydraulic drill equipped with a diamond drill bit was then used for internal inspection, confirming the specific form of the defect using an endoscope (model: 8mm diameter).

[0025] In one embodiment of the present invention, see Figure 2 、 Figure 5 and Figure 6 The drilling and filling method is suitable for repairing local defects with a cavity size of ≤15cm, a depth of ≤1 / 3 of the hole diameter, and no structural damage to the bellows. The specific steps of the drilling and filling method are as follows: (1) During construction, the BIM model coordinate positioning system is first used in combination with a steel bar scanner for precise positioning, with the error controlled within ±5mm. Then, a hydraulic drilling machine with a diamond drill bit is used to drill φ20±1mm grouting holes (hole spacing 40cm straight section / 30cm curved section) perpendicular to the axis of the channel in the defective area, and an φ8mm exhaust hole is added on the top of the corrugated pipe; (2) During the installation of the grouting system, a special grouting pipe with a check valve is implanted, and the gaps around the pipe are sealed with a quick-hardening sealant. The slurry is prepared by mixing P·O42.5 cement, silica fume (12%), UEA expansion agent (1%) and water reducer (0.2%) at a water-cement ratio of 0.32. A specific mixing process is used to ensure performance indicators such as fluidity of 12±1s and initial setting time ≥4h. (3) Grouting operation starts from the lowest hole using a ZBY-50 / 70 electric grouting pump, controlling the pressure to 0.6±0.05MPa and the speed to 3-5L / min. After the grouting is discharged from the adjacent hole, the next hole is moved to the next hole, and finally the grouting is completed from the highest exhaust hole and the pressure is maintained for 3 minutes. (4) 24 hours after grouting, the exposed grouting pipes were removed, and the holes were sealed with M50 non-shrinkage mortar and wet-cured for 7 days. During the construction process, the pressure-time curve was recorded in real time to ensure that the grouting volume of a single hole reached 120-150% of the theoretical void volume, the distance between adjacent holes was ≥50 cm, and the core strength at 28 days was ≥45 MPa. In case of slurry leakage, the pressure should be immediately reduced to 0.3 MPa and 0.5% accelerator should be added for intermittent grouting. During winter construction, the slurry temperature should be maintained at 10-25 °C and insulation measures should be taken. In a 35m box girder repair project, the average single-hole grouting volume of 12 cavities treated by this process was 2.8 L, the core strength at 28 days was 48.7-52.3 MPa, and the density reached 96.5-98.2%, which verified its good repair effect.

[0026] In one embodiment of the present invention, see Figure 4 In order to solve the longitudinal penetration defect of the bent section found in a bridge reinforcement project, the slotting repair method was adopted: During the slot repair construction of grouting defects in the curved section of the box girder, for serious cases such as through-hole defects (length ≥ 50 cm), severe deformation of the corrugated pipe (flattening rate ≥ 30%), or obvious corrosion of the prestressed tendons (area ≥ 10%), the "cut-off-rust prevention-connection-repair-sealing" process must be strictly followed; 1. Defective segment processing: Chisel away 50cm×30cm of the protective layer along the direction of the tunnel to fully expose the φ90mm metal bellows; Cut the corrugated pipe at a distance of ≥15cm from the edge of the defective area; Thoroughly clean the residual slurry and rust in the channel; 2. Repair construction: Spray 1.2mm thick rust inhibitor on exposed prestressed tendons; Use special connecting sleeves with compressive strength ≥50MPa to connect the cut-off parts; Formwork casting of M50 slightly expansive mortar (expansion rate 0.02%); When restoring the protective layer, add φ6@100mm steel wire mesh for reinforcement; 3. Special working condition processing: Temporary prestressing compensation is required for bridge repair during the operation period; The bellows partial replacement process is used in the sharp bend section with curvature radius R<8m; Set up removable inspection openings with a spacing of ≤3m; 4.Quality Control: Strictly follow JTG / TJ22-2008 and PTI specifications; Density after repair ≥95% (impact echo test); The load test verified that the bending stiffness recovered to 98% of the design value; This process requires 7 days of wet curing (geotextile covering and watering), and must pass special prestressing inspection to ensure that the original design load requirements are met; Specifically, the grooving repair method is suitable for treating serious defects with a length ≥50cm, a flattening rate of the corrugated pipe ≥30% or a rusted area of ​​the prestressed tendon ≥10%; before construction, three-dimensional laser scanning is required to accurately locate the defect area, and a hydraulic cutting machine is used to open a 50cm (length) × 30cm (width) U-shaped groove along the direction of the channel. The groove is deep enough to completely expose the corrugated pipe, and a special cutter is used to neatly cut the corrugated pipe 15cm away from the edge of the defect; the exposed prestressed tendons are first sandblasted (Sa2.5 grade) to remove rust, and then sprayed with a 1.2mm thick epoxy zinc-rich anti-corrosion coating (dry film zinc content ≥80%); during repair, a threaded connection sleeve with a compressive strength ≥50MPa is used to connect the fracture. During installation, a pre-tightening torque of 35 N·m is applied to ensure connection reliability; the micro-expansion mortar is cast with an M50 grade ratio (P·O42.5 cement: quartz sand: expansive agent = 1:1:0.12), a water-cement ratio of 0.28, and 0.8% polycarboxylate superplasticizer. When cast in layers, the thickness of each layer shall not exceed 10 cm, and a φ30 mm vibrator shall be used for compaction; when the protective layer is restored, a φ6@100 mm galvanized steel wire mesh shall be added, and connected to the original structural steel bars with stainless steel ties, with a node spacing of ≤20 cm; for bridge repairs during the operation period, a temporary prestressed compensation system (tensioning force is 15% of the design value) shall be installed simultaneously, and the compensation force shall be released three times within 72 hours after the repair is completed.

[0027] Application data from a specific project shows that this process achieves a 98.7% recovery rate in cross-section stiffness after repair, with a 28-day protective layer bond strength of ≥2.5 MPa. No cracking was observed after 2 million fatigue load tests, fully meeting the requirements of the JTG / T J22-2014 specification. A strain monitoring system should be used throughout the construction process to control stress redistribution during the grooving process and ensure structural safety.

[0028] In one embodiment of the present invention, see Figure 3 、 Figure 7 and Figure 8 The vacuum-assisted grouting method is suitable for repairing integral defects with large areas of looseness (defect range ≥ 1.5m). The construction method of the vacuum-assisted grouting method is as follows: (1) Before construction, an acoustic CT scan is required to determine the scope of the defect, and then a customized sealing cover (pressure resistance ≥ 1.0 MPa) is installed at both ends of the channel, and connected to the SZ-2 vacuum pump system through a φ20 mm high-pressure hose; (2) During formal operation, first start the vacuum pump to pump the system to -0.09~-0.10MPa and maintain it for 15 minutes. At the same time, use the intelligent temperature control system to keep the channel temperature within the range of 15~30℃; (3) The grouting material is modified ultrafine cement slurry (P·II 52.5 cement mixed with 20% mineral powder and 0.03% polycarboxylate water reducer) with a water-cement ratio of 0.30-0.32. After stirring for 3 min in a high-speed mixer (speed ≥ 1200 r / min), it is injected at a pressure of 0.7±0.05 MPa using an intelligent grouting trolley. The grouting speed is controlled at 4-6 L / min. During the grouting process, the vacuum degree change must be monitored in real time (fluctuation range ≤ 5%). When the exhaust pipe overflows with slurry of uniform consistency, the vacuum state is maintained for 10 min, and then the valve is closed to maintain pressure for 30 min. The sealing device is removed after 24 hours. (4) In special cases, for sharp bends with a curvature radius of less than 10m, 3 to 5 auxiliary exhaust valves should be added at the top, and a segmented stepped grouting process should be adopted; Applications in a certain project have shown that this process can increase the slurry filling degree to 98.3%, the 28d strength to 55.6MPa, and the pass rate for pore density detection to 100%. Compared with the traditional grouting process, the work efficiency is improved by 40%, and the occurrence of secondary defects is effectively avoided. An automated monitoring system should be used throughout the construction process to record key parameters such as vacuum degree, grouting pressure, and slurry temperature, and form a digital construction file.

[0029] In one embodiment of the present invention, see Figures 1-8 , quality acceptance specifically includes: After 72 hours of repair, the (IE-05) impact echo detector was used for re-inspection, which showed that the density reached 96.3%, which meets the requirements of JTG / T F50-2011.

[0030] In addition, during the construction process, the following matters need to be noted: 1. Before drilling, a steel bar scanner must be used to avoid prestressed bars; 2. Antifreeze must be added to the slurry during winter construction and insulation measures must be taken; 3. For cantilever box girders, temporary support and reinforcement are required during the repair phase.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A construction method for repairing defects in grouting holes in the curved section of a box beam and improving its density, characterized in that: The method comprises the following steps: Step (1) hole inspection and defect location: Use a multifunctional concrete non-destructive testing instrument and an endoscope to inspect the hole and determine the location and range of the non-compacted area; Step (2) defect classification and graded repair construction: the defects are divided into level I defects, level II defects and level III defects, where level I defects are local void defects, level II defects are overall defects, and level III defects are serious loose defects; a. For local void defects, use the drilling and filling method to inject ultra-fine cement slurry or epoxy resin; b. For integral defects, a vacuum-assisted grouting process is used. After sealing both ends of the duct, vacuum is drawn and then secondary grouting is performed. c. For serious non-compact defects, adopt the slotting repair method, remove the protective layer, remove the loose slurry, and fill with micro-expansion mortar; Step (3) Quality acceptance: After the repair is completed, the density is tested using the impact echo method.

2. The method for repairing defects and improving the density of grouting holes in the bent section of a box beam according to claim 1 is characterized in that: The ultrafine cement slurry in step (2) a is prepared with P·O42.5 cement, with a water-cement ratio of 0.3-0.35, and is added with 0.5%-1% UEA expansion agent, 12% silica fume and 0.2% water reducer. After the stirring process, the fluidity is ensured to be 12±1s and the initial setting time is ≥4h.

3. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 2 is characterized in that: In step (2) a, a hydraulic drilling machine equipped with a diamond drill bit is used to drill φ20±1mm grouting holes perpendicular to the axis of the channel in the defective area, with a hole spacing of 40cm in the straight section and 30cm in the curved section, and an additional φ8mm exhaust hole is provided on the top of the corrugated pipe; When installing the grouting system, a special grouting pipe with a check valve is implanted, and the gaps around the pipe are sealed with quick-hardening sealant.

4. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 3 is characterized in that: In step (2) a, an electric grouting pump is used to start grouting from the lowest hole, controlling the pressure to 0.6±0.05 MPa and the speed to 3-5 L / min. After the adjacent hole is slurried, the grouting operation is switched to the next hole, and finally the grouting operation is completed from the highest exhaust hole and the pressure is maintained for 3 minutes; 24 hours after the grouting is completed, the exposed grouting pipe is removed, and the holes are sealed with M50 non-shrinkage mortar and wet-cured for 7 days. The pressure-time curve is recorded in real time during the construction process, so that the grouting volume of a single hole reaches 120-150% of the theoretical void volume, the distance between adjacent holes is ≥50cm, and the core strength at 28 days is ≥45MPa.

5. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 1 is characterized in that: Before the groove repair method in step (2) b is performed, three-dimensional laser scanning is used to accurately locate the defective area, and a hydraulic cutting machine is used to open a U-shaped groove along the direction of the channel. The groove is deep enough to completely expose the corrugated pipe, and a special cutter is used to neatly cut the corrugated pipe 15 cm away from the edge of the defect; The exposed prestressed steel bars are first sandblasted to remove rust, and then sprayed with a 1.2mm thick epoxy zinc-rich anti-corrosion coating.

6. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 5 is characterized in that: During the repair in step (2) b, a threaded connection sleeve with a compressive strength of ≥50 MPa is used to connect the fracture, and a pre-tightening torque of 35 N·m is applied during installation.

7. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 1 is characterized in that: Before the vacuum-assisted grouting process in step (2) c is carried out, an acoustic CT scan is used to determine the defect range, sealing covers are installed at both ends of the channel, and a vacuum pump system is connected through a φ20mm high-pressure hose; Start the vacuum pump and control the vacuum degree to above -0.08MPa and maintain it for 15 minutes, while keeping the channel temperature within the range of 15 to 30℃.

8. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 7 is characterized in that: In step (2) c, the grouting material is modified ultrafine cement slurry, the proportion of which is P·II 52.5 cement mixed with 20% mineral powder and 0.03% polycarboxylate water reducer, with a water-cement ratio of 0.30-0.

32. After stirring in a mixer for 3 minutes, it is injected at a pressure of 0.5-0.8 MPa, and the grouting speed is controlled at 4-6 L / min. During the grouting process, the changes in vacuum degree need to be monitored in real time. When slurry with consistent consistency overflows from the exhaust pipe, the vacuum state should be maintained for 10 minutes, and then the valve should be closed to maintain the pressure for 30 minutes. The sealing device should be removed after 24 hours.

9. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 1 is characterized in that: Add exhaust holes every 3-5m in the bend section; For sharp bends with a curvature radius of less than 10m, 3 to 5 auxiliary exhaust valves must be added to the top, and a segmented stepped grouting process must be adopted; For sharp bends with a curvature radius R < 8m, the corrugated pipe local replacement process is adopted, and detachable inspection openings with a spacing of ≤ 3m are set.

10. The construction method for repairing defects and improving the density of grouting holes in the curved section of a beam according to claim 1 is characterized in that: During winter construction, antifreeze must be added to the slurry and insulation measures must be taken to keep the slurry temperature within the range of 10-25°C.

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