Repair method capable of effectively treating serious defects of operation small box girder bridge bottom plate

Abstract

The invention relates to the technical field of bridge maintenance, in particular to a repair method capable of effectively treating serious defects of a bottom plate of an operation small box girder bridge, which comprises the following steps: S1, preparation work: comprehensively checking a small box girder, determining the damage range and degree and marking a damage area, S2, forming a cleaning hole and a mud jacking hole, and S3, carrying out construction of the cleaning hole and the mud jacking hole. The method comprises the following steps: S1, determining a small box girder to be repaired, forming cleaning holes in a web plate and a bottom plate of the small box girder, and forming a grouting hole in the bottom plate of the small box girder, S3, cleaning the small box girder, and removing loose concrete and abnormal materials by extending a high-pressure water gun into a cavity of the small box girder to enable an interface to be fresh and rough, S4, carrying out pressure injection of a grouting material, and S5, an outer formwork is installed at the bottom of the beam, the periphery of the outer formwork is sealed through sealant, it is ensured that grouting materials cannot leak in the pressure injection process, after sealing is completed, cement-based grouting materials are injected into an inner cavity of the small box beam in a segmented pressure injection mode through the grouting holes, and the thickness of a repairing layer of each segment is controlled, and S5, the outer formwork, the plugging cleaning holes and the grouting holes are removed.

Description

[Technical field]

[0001] The invention relates to the technical field of bridge maintenance, and in particular to a repair method capable of effectively treating serious defects of a bottom plate of an operating small box girder bridge. [Background technology]

[0002] With the country's continuous investment in transportation infrastructure construction, the scale of the bridge engineering industry continues to expand. By the end of 2023, my country will have about 1.08 million highway bridges, including 10,239 super-large bridges and 177,700 large bridges. With the continuous growth of traffic volume and traffic load, the durability of concrete structures has decreased, and the maintenance of operating bridges will be an important area of ​​the civil engineering industry in the future.

[0003] Prefabricated small box girders have the advantages of simple appearance, good structural stress, convenient construction, economical and practical, and few defects. They are widely used in bridge construction, especially in the span range of 20m to 35m, where small box girders have the best economy and applicability. However, in the early construction process, due to the small thickness of the bottom plate of the small box girder and the lax control of concrete pouring and vibration, the bottom plate had defects such as insufficient thickness, local voids, local exposure of steel bars or corrugated pipes, and the presence of loose layers or abnormal interlayers.

[0004] In the prior art, the treatment of defects in the bottom plate of a small box girder mainly uses epoxy mortar / epoxy fine stone concrete to repair local honeycomb surface, exposed steel bars and other defects from the outside of the bottom plate; for serious defects such as serious lack of bottom plate thickness in a large area, and widespread exposure of steel bars or corrugated pipes, the main methods used are the top plate opening and manual entry repair method, steel plate bonding auxiliary reinforcement method and beam replacement method. The top plate opening and manual entry repair method is to close the traffic, partially chisel out the bridge deck pavement, and chisel out a manhole in the top plate of the small box girder. After the construction personnel enter, they chisel out the loose concrete. After processing the interface, they arrange the connecting steel bars and re-pour the concrete to restore the local top plate and bridge deck pavement of the small box girder. During the construction period, the traffic on the bridge needs to be closed. The construction process is complicated, the damage to the small box girder is large, and the stress distribution is affected. The construction period is long and the cost is high. The conventional steel plate bonding reinforcement method is an auxiliary reinforcement method. It does not directly repair the defects such as the thin thickness of the bottom plate of the small box girder and the exposed steel bars. It is a temporary solution and the effect is not obvious. The beam replacement method is to replace small box girders with defects that cannot / are difficult to repair. It has a huge impact on traffic, causes great traffic resistance and high costs due to interruption of operating roads, is difficult to construct, requires large machinery and equipment to work together, has a long construction period and high cost.

[0005] In view of the above technical problems, the present invention is proposed after research. [Summary of the invention]

[0006] The technical problem to be solved by the present invention is to provide a repair method that can effectively treat serious defects in the bottom plate of an operating small box girder bridge. By opening cleaning holes on the web and the bottom plate and using cement-based grouting materials for segmented injection, the problems of small box girder bottom plate thickness being small, and poor control of concrete pouring and vibration resulting in insufficient bottom plate thickness, local voids, local exposure of steel bars or corrugated pipes, and the presence of loose layers or abnormal interlayers can be effectively solved.

[0007] In order to solve the above technical problems, the present invention proposes a repair method that can effectively treat the serious defects of the bottom plate of a small box girder bridge in operation. The small box girder includes a bottom plate, a panel, and two webs arranged between the bottom plate and the panel. The upper end of the web is connected to the panel, and the lower end of the web is connected to the bottom plate. The bottom plate, the panel and the two webs form a hollow shape. The repair method for the serious defects of the bottom plate of the small box girder bridge in operation includes the following steps:

[0008] S1, preparation work, including comprehensive inspection of the small box girder, determination of the damage scope and extent, and marking of the damaged area;

[0009] S2, opening cleaning holes and grouting holes. After determining the small box girder to be repaired, a cleaning hole is opened on the web and bottom plate of the small box girder, and a grouting hole is opened on the bottom plate of the small box girder;

[0010] S3, cleaning the small box girder, using a high-pressure water gun to reach into the small box girder cavity to remove loose concrete and abnormal materials, making the interface fresh and rough;

[0011] S4, inject grouting material, install the outer formwork at the bottom of the beam and seal it with sealant around it to ensure that the grouting material will not leak during the injection process. After the sealing is completed, inject cement-based grouting material into the inner cavity of the small box beam in sections through the grouting holes, and control the thickness of the repair layer of each section;

[0012] S5, remove the outer formwork and seal, conduct strength test on the repair area, and after passing the inspection, remove the outer formwork and seal the cleaning holes and grouting holes.

[0013] As described above, a repair method that can effectively treat serious defects in the bottom plate of an operating small box girder bridge is described. In S2, before drilling the cleaning hole, the positions of the steel bars and steel strands on the bottom plate and web are determined by a steel bar positioning device to facilitate avoiding them when drilling.

[0014] As described above, a repair method that can effectively treat serious defects in the bottom plate of a small box girder bridge in operation is described. In S4, a ruler can be inserted and a camera is installed at an adjacent hole, and the thickness of the repair layer of each segment is controlled by imaging in the hole.

[0015] As described above, a repair method that can effectively treat serious defects in the bottom slab of a small box girder bridge in operation is described. In S4, several steps are formed by spraying concrete at the sub-segments, and grouting is performed section by section from low to high to control the thickness of the repair layer.

[0016] As described above, a repair method that can effectively treat serious defects of the bottom slab of an operating small box girder bridge, in S4, the segmented grouting method includes dividing the inner cavity of the small box girder into multiple grouting areas according to the size and shape of the defective area, and grouting is performed area by area.

[0017] As described above, a repair method that can effectively treat serious defects in the bottom plate of an operating small box girder bridge is described. In S3, after removing loose concrete and abnormal materials, skeleton steel bars are laid at the bottom of the bottom plate.

[0018] As described above, a repair method that can effectively treat serious defects in the bottom plate of an operating small box girder bridge is described. The skeleton reinforcement is composed of a wire mesh and a U-shaped steel bar. The wire mesh is connected to the U-shaped steel bar and the existing steel bars on the bottom plate by spot welding, thereby forming a stable supporting structure.

[0019] As described above, a repair method that can effectively treat serious defects of the bottom slab of a small box girder bridge in operation, in S4, the cement-based grouting material is a dry mix made by mixing cement, aggregate, admixture and mineral admixture.

[0020] As described above, a repair method that can effectively treat serious defects in the bottom plate of a small box girder bridge in operation, the outer formwork is made of lightweight, high-strength material.

[0021] Compared with the prior art, the repair method of the present invention, which can effectively treat the serious defects of the bottom plate of the small box girder bridge in operation, has the following advantages:

[0022] 1. By opening cleaning holes on the web and bottom plate, the problem of small box girder cavity size, inability to enter manually for operation, and top plate grooving damaging small box girder is solved. The damage to the original structure is small, the construction is simpler, more efficient, and the cost is lower.

[0023] 2. The cement-based grouting material injected in sections can take advantage of its good fluidity, micro-expansion, and high strength. The repair layer formed has good integration with the existing structure and high strength. It can also avoid unnecessary material waste, reduce construction costs, and reduce the impact on the environment.

[0024] 3. The segmented cement-based grouting method can solve the problems in the early construction process, such as the small thickness of the bottom plate of the small box girder, the lax control of concrete pouring and vibration, which leads to insufficient thickness of the bottom plate, local voids, local exposure of steel bars or corrugated pipes, and the existence of loose layers or abnormal interlayers.

[0025] 4. By drilling holes and grouting the bottom plate or web of the small box girder under the bridge, the construction work will not interfere with the traffic on the bridge.

Brief Description of the Drawings

[0026] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Figure 2 It is a structural schematic diagram of the U-shaped steel bar in the present invention.

[0029] Figure 3 It is a structural schematic diagram of the insufficient thickness of the bottom plate of the small box beam in the present invention.

[0030] Figure 4 It is another structural schematic diagram of the present invention.

[0031] In the figure: 1. small box girder; 10. bottom plate; 11. panel; 12. web plate; 3. cleaning hole; 4. grouting hole; 5. outer formwork; 6. cement-based grouting material; 7. steel wire mesh; 8. U-shaped steel bar. [Specific implementation method]

[0032] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] like Figure 1-4 As shown, the present invention includes a repair method that can effectively treat serious defects of the bottom plate of a small box girder bridge in operation. The small box girder 1 includes a bottom plate 10, a panel 11, and two webs 12 arranged between the bottom plate 10 and the panel 11. The upper end of the web 12 is connected to the panel 11, and the lower end of the web 12 is connected to the bottom plate 10. The bottom plate 10, the panel 11 and the two webs 12 form a hollow shape. The repair method for serious defects of the bottom plate of a small box girder bridge in operation includes the following steps:

[0034] S1, preparation work, includes comprehensive inspection of the small box girder 1, determination of the damage scope and extent, and marking of the damaged area.

[0035] S2, opening cleaning holes 3 and grouting holes 4. After determining the small box girder 1 to be repaired, a cleaning hole 3 is opened on the web 12 and the bottom plate 10 of the small box girder 1, and a grouting hole 4 is opened on the bottom plate 10 of the small box girder 1. Figure 4 In this step, cleaning holes 3 can be opened at intervals according to the damaged position of the small box girder 1 for better cleaning. In addition, by opening holes and grouting the bottom plate 10 or the web 12 of the small box girder 1 under the bridge, the construction work does not interfere with the traffic on the bridge.

[0036] S3, cleaning the small box beam 1, using a high-pressure water gun to reach into the cavity of the small box beam 1 to remove loose concrete and abnormal materials, so that the interface is fresh and rough. By opening the cleaning hole 3 on the web 12 and the bottom plate 10, the problem of the small size of the inner cavity of the box beam, the inability to enter manually for operation, and the problem of the small box beam 1 being damaged by the top plate slotting is solved, and the damage to the original structure is small.

[0037] S4, inject grouting material, install the outer formwork 5 at the bottom of the beam and seal it with sealant around it to ensure that the grouting material will not leak during the injection process. After the sealing is completed, the cement-based grouting material 6 is injected into the inner cavity of the small box beam 1 through the grouting hole 4 in sections, and the thickness of the repair layer of each section is controlled. The segmented injection can ensure that the cement-based grouting material 6 in each damaged area can be fully filled, avoiding the insufficient structural strength caused by the uneven distribution of the cement-based grouting material 6. Since the internal structure of the small box beam 1 is relatively complex and there are various gaps and cracks, the segmented injection can accurately grout these areas, thereby improving the density and uniformity of the grouting. In addition, the segmented injection can be carried out in sections, which is conducive to organizing the construction. This can not only reduce the workload of a single grouting, but also make the construction process more orderly and efficient. At the same time, the segmented injection can also help to promptly discover and solve problems that may arise during the grouting process, such as grouting material blockage, insufficient pressure, etc., thereby ensuring the quality and progress of the construction. On the other hand, the segmented injection can adjust the amount of cement-based grouting material 6 according to the actual grouting requirements, thereby avoiding unnecessary material waste. This can not only reduce construction costs, but also reduce the impact on the environment.

[0038] This step can solve the problem that in the early construction process, the thickness of the small box girder bottom plate is small, and the concrete pouring and vibration are not strictly controlled, resulting in defects such as insufficient thickness of the bottom plate 10, local voids, local exposure of steel bars or corrugated pipes, loose layers or abnormal interlayers.

[0039] S5, remove the outer formwork 5 and plugging, perform strength test on the repair area, and after passing the inspection, remove the outer formwork 5, plug the cleaning hole 3 and the grouting hole 4. The outer formwork 5 is made of lightweight and high-strength material, which is easy to install and transport, and has excellent supporting strength.

[0040] Through the above steps, it can be known that the present application is a repair method that can effectively treat serious defects in the bottom plate of an operating small box girder bridge, and has the advantages of fast maintenance and construction speed, simple repair technology, and good economy. By opening a cleaning hole 3 on the web 12 and the bottom plate 10, the problem of the small size of the inner cavity of the box girder, the inability to enter manually for operation, and the problem of the small box girder 1 being damaged by the top plate grooving is solved, and the damage to the original structure is small. In addition, the cement-based grouting material injected in sections, using its good fluidity, micro-expansion, high strength and other characteristics, the repair layer formed is well combined with the existing structure and has high strength, and can also avoid unnecessary material waste, reduce construction costs, and reduce the impact on the environment.

[0041] As a further solution of this embodiment, before drilling the cleaning hole 3, the position of the steel bars and steel strands on the bottom plate 10 and the web 12 is determined by a steel bar positioning device, so as to avoid them when drilling. After the position of the steel bars and steel strands is determined, the construction can be facilitated and the damage to the original structure can be reduced.

[0042] As a preferred solution of this embodiment, in S4, a ruler can be inserted and a camera is installed at an adjacent hole, so that the thickness of the repair layer of each segment can be controlled by imaging in the hole.

[0043] As another preferred solution of this embodiment, in S4, several steps are formed by spraying concrete at the sub-segments, and grouting is performed step by step from low to high to control the thickness of the repair layer.

[0044] As a further solution of this embodiment, in S4, the segmented grouting method includes dividing the inner cavity of the small box beam 1 into multiple grouting areas according to the size and shape of the defective area, and grouting is performed in each area. Similarly, the inner cavity is divided into multiple grouting areas for construction, and the amount of cement-based grouting material 6 can be filled according to the loss situation, so that it can be better combined with the loss position and have better connection strength. At the same time, it can also avoid unnecessary material waste, reduce construction costs, and reduce the impact on the environment.

[0045] As a further solution of this embodiment, in S3, after removing the loose concrete and abnormal materials, a skeleton steel bar is laid at the bottom of the bottom plate 10. The skeleton steel bar is composed of a steel mesh 7 and a U-shaped steel bar 8. The steel mesh 7 is connected to the U-shaped steel bar 8 and the existing steel bars on the bottom plate 10 by spot welding, thereby forming a stable support structure. After setting up the steel skeleton, better support strength can be achieved. Figure 3 As shown, if the thickness of the bottom plate 10 of the small box girder 1 is insufficient, this step may not be taken.

[0046] As a further solution of this embodiment, in S4, the cement-based grouting material 6 is a dry mixture made by mixing cement, aggregate, admixture and mineral admixture. Aggregate includes fine aggregate and coarse aggregate. Fine aggregate includes quartz sand, river sand and machine-made sand (usually with a particle size of 0.075-2.36 mm), which is used to fill the gaps between cement particles and improve density. Coarse aggregate includes small-size crushed stone (such as 2.36-4.75 mm). Some high-strength grouting materials may not contain coarse aggregate to maintain fluidity.

[0047] Admixtures include water reducers, expansive agents and early strength agents. Water reducers include polycarboxylic acid water reducers and naphthalene water reducers, which are used to reduce the water-cement ratio and improve fluidity and strength. Expansive agents include sulfoaluminates and calcium oxides, which are used to compensate for shrinkage and prevent cracking. Early strength agents include sodium sulfate and calcium formate, which are used to accelerate early strength development.

[0048] Mineral admixtures include fly ash and slag powder. Fly ash comes from coal-fired power plant ash (grade I / II) and is used to improve workability, reduce hydration heat, and save cement. Slag powder comes from blast furnace slag grinding (grade S75 / S95 / S105) and is used to enhance later strength and resistance to chemical corrosion.

Claims

1. A repair method capable of effectively treating serious defects of the bottom plate of an operating small box girder bridge, wherein the small box girder (1) comprises a bottom plate (10) and a face plate (11) and two web plates (12) arranged between the bottom plate (10) and the face plate (11), wherein the upper end of the web plate (12) is connected to the face plate (11), and the lower end of the web plate (12) is connected to the bottom plate (10), and the bottom plate (10), the face plate (11) and the two web plates (12) form a hollow shape, characterized in that A method for repairing serious defects of a bottom plate (10) of an operating small box girder (1) comprises the following steps: S1, preparation work, including comprehensive inspection of the small box girder (1), determination of the damage scope and extent, and marking of the damaged area; S2, opening a cleaning hole (3) and a grouting hole (4), after determining the small box girder (1) to be repaired, opening a cleaning hole (3) on the web (12) and the bottom plate (10) of the small box girder (1), and opening a grouting hole (4) on the bottom plate (10) of the small box girder (1); S3, cleaning the small box girder (1), using a high-pressure water gun to reach into the cavity of the small box girder (1) to remove loose concrete and abnormal materials, so that the interface is fresh and rough; S4, injecting grouting material, installing the outer formwork (5) at the bottom of the beam and sealing the periphery with sealant to ensure that the grouting material does not leak during the injection process, and then injecting cement-based grouting material (6) into the inner cavity of the small box beam (1) in sections through the grouting holes (4) after the sealing is completed, and controlling the thickness of the repair layer of each section; S5, remove the outer formwork (5) and seal, perform strength test on the repair area, and after passing the inspection, remove the outer formwork (5), seal the cleaning hole (3) and the grouting hole (4).

2. A repair method for effectively treating serious defects in the bottom plate of an operating small box girder bridge according to claim 1, characterized in that In S2, before drilling the cleaning hole (3), the positions of the steel bars and steel strands on the bottom plate (10) and the web (12) are determined by a steel bar positioning device so as to avoid them when drilling.

3. A repair method for effectively treating serious defects in the bottom slab of an operating small box girder bridge according to claim 1, characterized in that In S4, a ruler can be inserted and a camera is installed at the adjacent hole, and the thickness of the repair layer of each segment is controlled by imaging in the hole.

4. A repair method for effectively treating serious defects in the bottom slab of an operating small box girder bridge according to claim 1, characterized in that In S4, several steps are formed by spraying concrete at the sub-segments, and grouting is carried out section by section from low to high to control the thickness of the repair layer.

5. The repair method according to claim 1, which can effectively treat the serious defects of the bottom plate of the small box girder bridge in operation, is characterized in that In S4, the segmented grouting method includes dividing the inner cavity of the small box girder (1) into a plurality of grouting areas according to the size and shape of the defective area, and performing grouting in each area one by one.

6. The repair method according to claim 1, which can effectively treat the serious defects of the bottom plate of the small box girder bridge in operation, is characterized in that In S3, after removing the loose concrete and abnormal materials, skeleton steel bars are laid at the bottom of the base plate (10).

7. A repair method for effectively treating serious defects in the bottom slab of an operating small box girder bridge according to claim 6, characterized in that The skeleton reinforcement is composed of a steel wire mesh (7) and a U-shaped reinforcement (8). The steel wire mesh (7) is connected to the U-shaped reinforcement (8) and the existing reinforcement on the bottom plate (10) by spot welding, thereby forming a stable supporting structure.

8. The repair method according to claim 1, which can effectively treat the serious defects of the bottom plate of the small box girder bridge in operation, is characterized in that In S4, the cement-based grouting material (6) is a dry mix made by mixing cement, aggregate, admixture and mineral admixture.

9. A repair method for effectively treating serious defects in the bottom slab of an operating small box girder bridge according to claim 1, characterized in that The outer template (5) is made of light and high-strength material.

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