A construction method for combining the old bridge structure with the new bridge overall structure

Abstract

The present invention discloses a construction method for combining the bridge structure of an old bridge with the overall structure of a new bridge. The method comprises the following steps: allocating sufficient personnel according to the working surface provided on site and the overall construction plan; conducting safety and technical briefings for all personnel; and providing certification to special operations personnel before taking up their posts. The method is required to be familiar with and review drawings, understand the design content, clarify the equipment and materials used in the project, clarify the construction requirements proposed in the drawings, and move the negative bending moment of the top plate to the bridge deck pavement. The method effectively ensures the stability of the structure and facilitates the construction of the negative bending moment of the top plate, greatly saving construction costs and shortening construction period. The original design of 108 pieces of 30m prefabricated small box girders and 48 pieces of 25m prefabricated small box girders is adjusted to 52 pieces of 30m prefabricated small box girders and 24 pieces of 25m prefabricated small box girders, effectively saving 80 pieces of prefabricated small box girders, saving a lot of construction period, and reducing the total project cost.

Description

Technical Field

[0001] The present invention relates to the technical field of bridges, and in particular to a construction method for combining an old bridge structure with an overall structure of a new bridge. Background Art

[0002] With the development of my country's expressway industry, more and more expressways are being built across its vast territory, improving transportation and facilitating people's lives. The Yangtze-Huaihe River Diversion Project connects the Yangtze and Huaihe River systems, nourishing Anhui, benefiting Henan, benefiting the Huaihe River, and radiating to the Yangtze River. It has enormous comprehensive benefits, including ensuring water supply, developing shipping, and improving the water environment.

[0003] Traditional highway reconstruction and expansion projects require a long time to demolish old bridges, have a great social impact, and have low work efficiency. Utilizing old bridges can reduce the total project cost, save the cost and time of building new bridges, facilitate construction, speed up the construction progress, and make full use of old bridges. It can also reduce waste storage space and disposal costs, saving a lot of materials and protecting the environment. Whether from the perspective of saving funds for building new bridges or improving the level of new bridge construction and protecting the environment, making full use of old bridges can bring into play their potential huge economic and social benefits. Summary of the Invention

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a construction method for combining the old bridge structure with the new bridge overall structure, comprising:

[0005] S1. According to the working surface and overall construction plan provided on site, sufficient personnel shall be deployed. All personnel shall receive safety and technical explanations. Special operation personnel shall be certified before taking up their posts. They shall be familiar with and review the drawings, understand the design content, clarify the equipment and materials used in the project, clarify the construction requirements proposed in the drawings, and clarify the cross-coordination between the old bridge reuse construction and other projects so that measures can be taken early to ensure that there are no location conflicts with other projects during the construction process. Familiar with other technical information related to the project, such as construction and acceptance specifications, technical regulations, quality inspection and evaluation standards, and product information provided by the manufacturer. Sufficient production materials shall be prepared before construction work. Main materials such as steel bars and concrete shall meet the requirements of relevant technical standards. Tests shall be conducted before use, and unqualified products shall not be used. Some steel products shall be processed in factories and transported to the construction site by the steel bar processing plant as the project progresses. Safety production explanations shall be conducted for on-site workers, and the sources of danger and precautions for on-site construction shall be clarified to ensure construction safety. The coordinates of each section of the new and old beams shall be calculated, and the measurement data shall be reviewed in a timely manner.

[0006] S2. The layout of the old bridge to be demolished is (5*30)*3 sections + (35+60+35)*1 section + (5*30)*2 sections + (3*30)*1 section. The entire bridge is located in a straight section with a total length of 976m. The main bridge is a (35+60+35)m cast-in-place continuous box girder with a total deck width of 34.5m. The remaining approach bridges are all 30m simply supported and then continuous small box girders with a total deck width of 34.5m. The bridge section is a two-way six-lane expressway. The main bridge of the old bridge and one approach bridge on each side, totaling 5*30+(35+60+35+5*30=430m, need to be demolished and rebuilt. The remaining approach bridges will be widened to eight lanes.

[0007] S3. After adopting this construction method, 52 pieces of 30m small box girders and 24 pieces of 20m small box girders need to be prefabricated, totaling 76 pieces. The construction procedure of the box girder reinforcement is to first tie the bottom plate and web reinforcement on the base. After forming, the whole is hoisted to the pedestal. Then, after the outer and inner forms are installed, the top plate reinforcement is tied. After the formwork is installed, its plane position, top elevation, joints, reserved hole sealing, node connection and longitudinal and transverse stability should be checked. Concrete pouring can only be carried out after acceptance by the supervising engineer.

[0008] S4, spans 1-14 and spans 18-29 are the approach bridge widening sections. One prefabricated side box girder was used on each side of the bridge to widen one lane, totaling 52 pieces. The side spans of the approach bridge on both sides of the original main bridge of the old bridge were demolished, and a total of two spans were rebuilt with 20-meter box girders, totaling 24 pieces. Two XCMG 220t cranes were used for the box girder hoisting and installation. Under the unified command of the lifting commander, the two cranes synchronously lifted the box girder into the air. When the lifting height of the beam exceeded the cap beam surface, the two cranes synchronously tilted and rotated their booms slowly. After the beam passed obliquely between the two booms, the booms were rotated again to correct the installation beam position, and then moved horizontally to the installation position and lowered to install it in place.

[0009] S5. Use a wire saw to cut the beam ends of piers 14# and 17# of the old bridge, while leaving the middle crossbeam of the old beam intact and roughening the ends of the middle crossbeam of the old beam. Remove 40cm of the top slab from the old bridge and weld it to the top slab of the new box girder. Use the old bridge's embedded rebar to weld the web and bottom slab steel bars to the new box girder's web and bottom slab steel bars. Then pour concrete.

[0010] S6. In the area from the negative bending moment notch of the 30m small box girder of the old bridge to the pier top, 10cm of C40 waterproof concrete of the old bridge was chiseled out. At the same time, 4cm of the concrete top plate of the old bridge box girder was milled to expose the steel bars of the box girder top plate, so as to better connect the concrete of the new and old beams. Φ16 steel bars were planted in the top plate of the old bridge. Before drilling the holes for planting steel bars, the positions of ordinary steel bars were identified. The holes were placed away from the positions of ordinary steel bars. The drilling depth and diameter of the holes were such that the planting depth of D16 steel bars was not less than 15cm. The adhesive used for planting steel bars was selected in accordance with the "Highway Bridge Reinforcement Design Code" (JTG / T 22-2008) performance index of Class A glue; and pre-embedded vertical steel bars in the newly built and widened prefabricated box girders; arranged transverse steel bars in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge, and the transverse steel bars were connected to the planted bars of the old bridge and the pre-embedded steel bars of the new bridge; within 1m after the end of the negative bending moment, Φ16 steel bars were used for dense setting, with a spacing of 15cm*15cm in the longitudinal and transverse directions of the bridge, and C40 waterproof concrete was poured in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge to achieve the connection of the negative bending moment area on the pier top.

[0011] Preferably, the ends of the 14# and 17# pier beams of the old bridge are cut with a rope saw, while the middle cross beam of the old beam is kept intact, and the ends of the middle cross beam of the old beam are roughened, drilled and rebar is planted, and connected with the new cast-in-place middle cross beam steel bars; double-legged annular steel bars are used at the wider positions of the widened wet joints, and D12 reinforcing steel bars are added to the bridge deck pavement at the widened wet joints.

[0012] Preferably, the negative bending moment of the top plate is moved to the bridge deck pavement layer, and transverse steel bars are arranged in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge. The transverse steel bars are connected with the embedded steel bars of the old bridge and the embedded steel bars of the new bridge.

[0013] Preferably, C40 waterproof concrete is used from the negative bending moment notch of the old bridge to the negative bending moment notch area of ​​the newly built bridge to achieve the connection of the negative bending moment area on the pier top.

[0014] Preferably, the middle cross beam is connected by embedded steel bars; the longitudinal wet joint is milled, and the exposed steel bars are connected to the new beam after milling. The wet joint has a large rigidity, and the connection is strengthened by the steel bars at the middle cross beam and the longitudinal wet joint. The structural integrity is good, so that the new and old beam structures are subjected to stress together, ensuring that the structure has sufficient strength to resist the additional internal forces and deformations caused by shrinkage creep and foundation settlement.

[0015] Preferably, after each beam is installed in place and the beam body is in place, check whether the beam supports are stable. If there are any movable supports, the beam body should be re-lifted; after adjusting the supports, the beam body should be put in place again until all the supports of the beam body are stable before the next beam body can be installed, and after each adjacent two beams are installed, the connecting steel bars should be welded in time.

[0016] Preferably, the welding is carried out with the newly built 20m small box girder top plate steel bars, and the single-sided welding length is not less than 10d; double-limb annular steel bars are used at the wider position of the widened wet joint, and D12 reinforcing steel bars are added to the bridge deck pavement at the widened wet joint position; and then concrete pouring is carried out.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention transfers the negative bending moment of the top plate to the bridge deck pavement layer. This method effectively ensures the stability of the structure and facilitates the construction of the negative bending moment of the top plate, greatly saving construction costs and shortening construction period.

[0019] The original design of 108 pieces of 30m prefabricated small box girders and 48 pieces of 25m prefabricated small box girders was adjusted to 52 pieces of 30m prefabricated small box girders and 24 pieces of 25m prefabricated small box girders, effectively saving 80 pieces of prefabricated small box girders, saving a lot of construction time and reducing the total project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the construction process of the present invention;

[0021] Figure 2 This is a standard cross-sectional view of the approach bridge of the old bridge of the present invention;

[0022] Figure 3 This is a schematic diagram of the design and construction of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] See also Figure 1-3 The present invention provides a technical solution: a construction method for combining the old bridge structure with the new bridge overall structure, including a bridge,

[0025] S1. According to the working surface and overall construction plan provided on site, sufficient personnel shall be deployed. All personnel shall receive safety and technical explanations. Special operation personnel shall be certified before taking up their posts. They shall be familiar with and review the drawings, understand the design content, clarify the equipment and materials used in the project, clarify the construction requirements proposed in the drawings, and clarify the cross-coordination between the old bridge reuse construction and other projects so that measures can be taken early to ensure that there are no location conflicts with other projects during the construction process. Familiar with other technical information related to the project, such as construction and acceptance specifications, technical regulations, quality inspection and evaluation standards, and product information provided by the manufacturer. Sufficient production materials shall be prepared before construction work. Main materials such as steel bars and concrete shall meet the requirements of relevant technical standards. Tests shall be conducted before use, and unqualified products shall not be used. Some steel products shall be processed in factories and transported to the construction site by the steel bar processing plant as the project progresses. Safety production explanations shall be conducted for on-site workers, and the sources of danger and precautions for on-site construction shall be clarified to ensure construction safety. The coordinates of each section of the new and old beams shall be calculated, and the measurement data shall be reviewed in a timely manner.

[0026] S2. The layout of the old bridge to be demolished is (5*30)*3 sections + (35+60+35)*1 section + (5*30)*2 sections + (3*30)*1 section. The entire bridge is located in a straight section with a total length of 976m. The main bridge is a (35+60+35)m cast-in-place continuous box girder with a total deck width of 34.5m. The remaining approach bridges are all 30m simply supported and then continuous small box girders with a total deck width of 34.5m. The bridge section is a two-way six-lane expressway. The main bridge of the old bridge and one approach bridge on each side, totaling 5*30+(35+60+35+5*30=430m, need to be demolished and rebuilt. The remaining approach bridges will be widened to eight lanes.

[0027] S3. After adopting this construction method, 52 pieces of 30m small box girders and 24 pieces of 20m small box girders need to be prefabricated, totaling 76 pieces. The construction procedure of the box girder reinforcement is to first tie the bottom plate and web reinforcement on the base. After forming, the whole is hoisted to the pedestal. Then, after the outer and inner forms are installed, the top plate reinforcement is tied. After the formwork is installed, its plane position, top elevation, joints, reserved hole sealing, node connection and longitudinal and transverse stability should be checked. Concrete pouring can only be carried out after acceptance by the supervising engineer.

[0028] S4, spans 1-14 and spans 18-29 are the approach bridge widening sections. One prefabricated side box girder was used on each side of the bridge to widen one lane, totaling 52 pieces. The side spans of the approach bridge on both sides of the original main bridge of the old bridge were demolished, and a total of two spans were rebuilt with 20-meter box girders, totaling 24 pieces. Two XCMG 220t cranes were used for the box girder hoisting and installation. Under the unified command of the lifting commander, the two cranes synchronously lifted the box girder into the air. When the lifting height of the beam exceeded the cap beam surface, the two cranes synchronously tilted and rotated their booms slowly. After the beam passed obliquely between the two booms, the booms were rotated again to correct the installation beam position, and then moved horizontally to the installation position and lowered to install it in place.

[0029] S5. Use a wire saw to cut the beam ends of piers 14# and 17# of the old bridge, while leaving the middle crossbeam of the old beam intact and roughening the ends of the middle crossbeam of the old beam. Remove 40cm of the top slab from the old bridge and weld it to the top slab of the new box girder. Use the old bridge's embedded rebar to weld the web and bottom slab steel bars to the new box girder's web and bottom slab steel bars. Then pour concrete.

[0030] S6. In the area from the negative bending moment notch of the 30m small box girder of the old bridge to the pier top, 10cm of C40 waterproof concrete of the old bridge was chiseled out. At the same time, 4cm of the concrete top plate of the old bridge box girder was milled to expose the steel bars of the box girder top plate, so as to better connect the concrete of the new and old beams. Φ16 steel bars were planted in the top plate of the old bridge. Before drilling the holes for planting steel bars, the positions of ordinary steel bars were identified. The holes were placed away from the positions of ordinary steel bars. The drilling depth and diameter of the holes were such that the planting depth of D16 steel bars was not less than 15cm. The adhesive used for planting steel bars was selected in accordance with the "Highway Bridge Reinforcement Design Code" (JTG / T 22-2008) performance index of Class A glue; and pre-embedded vertical steel bars in the newly built and widened prefabricated box girders; arranged transverse steel bars in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge, and the transverse steel bars were connected to the planted bars of the old bridge and the pre-embedded steel bars of the new bridge; within 1m after the end of the negative bending moment, Φ16 steel bars were used for dense setting, with a spacing of 15cm*15cm in the longitudinal and transverse directions of the bridge, and C40 waterproof concrete was poured in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge to achieve the connection of the negative bending moment area on the pier top.

[0031] Use a rope saw to cut the ends of the 14# and 17# pier beams of the old bridge, while keeping the middle cross beam of the old beam intact, and roughen the ends of the middle cross beam of the old beam, drill holes and plant reinforcement, and connect them with the new cast-in-place middle cross beam reinforcement; use double-legged circular reinforcement at the wider position of the widened wet joint, add D12 reinforcement steel bars at the widened wet joint position of the bridge deck, move the negative bending moment of the top plate to the bridge deck pavement layer, arrange transverse reinforcement in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge, connect the transverse reinforcement with the planted reinforcement of the old bridge and the embedded reinforcement of the new bridge, build C40 waterproof concrete in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge, and realize the connection of the negative bending moment area of ​​the pier top.

[0032] The middle cross beam is connected by embedded reinforcement; the longitudinal wet joint is milled, and the exposed steel bars are connected to the new beam after milling. The wet joint has greater rigidity, and the connection is strengthened by the steel bars at the middle cross beam and longitudinal wet joint, so the structural integrity is good, so that the new and old beam structures are subjected to stress together, ensuring that the structure has sufficient strength to resist the additional internal forces and deformations caused by shrinkage, creep and foundation settlement. After each beam is installed in place, the beam support is checked for stability. If there are any movable supports, the beam should be re-lifted; after adjusting the supports, the beam is put into place again until all the supports of the beam are stable before the next beam can be installed. After each adjacent beam is installed, its connecting steel bars are welded in time and welded to the new 20m small box beam top plate steel bars by welding. The single-sided welding length is not less than 10d; double-legged circular steel bars are used at the wider position of the spliced ​​wet joint, and D12 reinforcing steel bars are added to the bridge deck pavement at the spliced ​​wet joint position; then concrete is poured.

[0033] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for combining an old bridge structure with a new bridge overall structure, comprising: S1. According to the working surface and overall construction plan provided on site, sufficient personnel shall be deployed. All personnel shall receive safety and technical explanations. Special operation personnel shall be certified before taking up their posts. They shall be familiar with and review the drawings, understand the design content, clarify the equipment and materials used in the project, clarify the construction requirements proposed in the drawings, and clarify the cross-coordination between the old bridge reuse construction and other projects so as to take measures in advance to ensure that there is no location conflict with other projects during the construction process; be familiar with other technical information related to the project, and be equipped with sufficient production materials before construction. The main materials of steel bars and concrete shall meet the requirements of relevant technical standards and be tested and verified before use. Unqualified products shall not be used. Some steel products shall be processed in factories and transported to the construction site by the steel bar processing plant as the progress of the project requires. Safety production explanations shall be given to on-site workers, and the sources of danger and precautions for on-site construction shall be clarified to ensure construction safety. The coordinates of each section of the new and old beams shall be calculated and the measurement data shall be reviewed in a timely manner. S2. The layout of the old bridge to be demolished is 5*30*3 sections + main bridge*1 section + 5*30*2 sections + 3*30*1 section. The entire bridge is located in a straight section, with a total length of 976m. The main bridge is a 35+60+35m cast-in-place continuous box girder with a total deck width of 34.5m. The remaining approach bridges are all 30m simply supported and then continuous small box girders with a total deck width of 34.5m. The bridge section is a two-way six-lane expressway. The main bridge of the old bridge and one approach bridge on each side (5*30+35+60+35+5*30=430m) need to be demolished and rebuilt, and the remaining approach bridges will be widened to eight lanes. S3. After adopting this construction method, 52 pieces of 30m small box girders and 24 pieces of 20m small box girders need to be prefabricated, totaling 76 pieces. The construction procedure of the box girder reinforcement is to first tie the bottom plate and web reinforcement on the base. After forming, the whole is hoisted to the pedestal. Then, after the outer and inner forms are installed, the top plate reinforcement is tied. After the formwork is installed, its plane position, top elevation, joints, reserved hole sealing, node connection and longitudinal and transverse stability should be checked. Concrete pouring can only be carried out after acceptance by the supervising engineer. S4, spans 1-14 and spans 18-29 are the approach bridge widening sections. One prefabricated side box girder was used on each side of the bridge to widen one lane, totaling 52 pieces. The side spans of the approach bridge on both sides of the original main bridge were demolished, and a total of two spans were rebuilt with 20-meter box girders, totaling 24 pieces. Two XCMG 220t cranes were used for box girder installation. Under the unified command of the lifting commander, the two cranes simultaneously lifted the box girder into the air. When the lifting height of the beam exceeded the cap beam surface, the two cranes synchronously tilted their booms and slowly rotated. After the beam passed obliquely between the two booms, the booms were rotated again to correct the installation beam position, and then moved horizontally to the installation position and lowered to install it in place. S5. Use a wire saw to cut the beam ends of piers 14# and 17# of the old bridge, while leaving the middle crossbeam of the old beam intact and roughening the ends of the middle crossbeam. Remove 40 cm of the top plate from the old bridge and weld the top plate steel bars of the newly built box beam. Use the old bridge's embedded steel bars to weld the web and bottom plate steel bars to the new box beam's web and bottom plate steel bars. Then pour concrete. S6. In the area from the negative bending moment notch of the 30m small box girder of the old bridge to the pier top, remove 10cm of C40 waterproof concrete from the old bridge. At the same time, mill 4cm of the concrete top plate of the old bridge box girder to expose the steel bars of the box girder top plate, so as to better connect the new and old beam concrete. Plant Φ16 steel bars on the top plate of the old bridge. Before drilling the holes for planting steel bars, locate the ordinary steel bars. The holes should avoid the locations of ordinary steel bars. The drilling depth and diameter should meet the requirements of D16 steel bar planting depth of not less than 15cm. The adhesive used for planting steel bars should comply with the "Highway Bridge Reinforcement Design Code" JTG / TJ2. 2-2008 performance index Class A glue; and pre-embedded vertical steel bars in the newly built and widened prefabricated box girders; arrange transverse steel bars in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge, and the transverse steel bars are connected with the planted bars of the old bridge and the pre-embedded steel bars of the new bridge; within 1m after the end of the negative bending moment, use Φ16 steel bars for dense setting, with a spacing of 15cm*15cm in the longitudinal and transverse directions of the bridge, and pour C40 waterproof concrete in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge to achieve the connection of the negative bending moment area on the pier top.

2. The construction method for combining the old bridge structure with the new bridge overall structure according to claim 1, characterized in that: The ends of the 14# and 17# pier beams of the old bridge were cut with a rope saw, while the middle cross beam of the old beam was kept intact, and the ends of the middle cross beam of the old beam were roughened, drilled and rebar was planted, and connected with the steel bars of the newly cast-in-place middle cross beam; double-legged circular steel bars were used at the wider positions of the widened wet joints, and D12 reinforcing steel bars were added to the bridge deck pavement at the widened wet joints.

3. The construction method for combining the old bridge structure with the new bridge overall structure according to claim 2 is characterized by: The negative bending moment of the top plate is moved to the bridge deck pavement layer, and transverse steel bars are arranged in the area from the negative bending moment notch of the old bridge to the negative bending moment notch of the new bridge. The transverse steel bars are connected with the embedded steel bars of the old bridge and the embedded steel bars of the new bridge.

4. The construction method for combining the old bridge structure with the new bridge overall structure according to claim 3 is characterized by: Pour C40 waterproof concrete from the negative bending moment notch of the old bridge to the negative bending moment notch area of ​​the new bridge to achieve the connection of the negative bending moment area on the pier top.

5. The construction method for combining the old bridge structure with the new bridge overall structure according to claim 4 is characterized by: Embedded reinforcement is used in the middle cross beam; the longitudinal wet joint is milled, and the exposed steel bars are connected to the new beam after milling. The wet joint has greater rigidity, and the connection is strengthened by the steel bars in the middle cross beam and longitudinal wet joint. The structural integrity is good, so that the new and old beam structures are subjected to stress together, ensuring that the structure has sufficient strength to resist the additional internal forces and deformations caused by shrinkage, creep and foundation settlement.

6. The construction method for combining the old bridge structure with the new bridge overall structure according to claim 5, characterized in that: After each beam is installed and the beam body is in place, check whether the beam supports are stable. If there are any movable supports, the beam body should be re-lifted; after adjusting the supports, the beam body should be put into place again until all the supports of the beam body are stable. Only then can the next beam body be installed. After each adjacent beam is installed, the connecting steel bars should be welded in time.

7. The construction method for combining the old bridge structure with the new bridge overall structure according to claim 6, characterized in that: Weld it to the newly built 20m small box girder top plate steel bar by welding, and the single-sided welding length shall not be less than 10d; double-legged circular steel bars are used at the wider position of the spliced ​​wet joint, and D12 reinforcing steel bars are added to the bridge deck pavement at the position of the spliced ​​wet joint; then concrete is poured.

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