Bailey bridge jacking construction method

Abstract

The invention discloses a Bailey bridge jacking construction method, relates to the technical field of Bailey bridge construction, and is suitable for Bailey bridge upgrading and reconstruction in water conservancy and hydropower, traffic, emergency rescue and other scenes. The construction method comprises the steps of construction early-stage preparation, supporting system arrangement, synchronous jacking and profile steel supporting cushion, pier heightening concrete pouring, bridge body seating and equipment removal. Materials are intensively stacked at the position 10-20 m away from a bridge abutment, a safety protection facility is built, a 100-ton jack is adopted for synchronous jacking, structural steel is matched for supporting cushions layer by layer, the jacking difference is controlled to be not larger than 20 cm, concrete is poured every time the materials are lifted by 2 m, and operation is repeated to the designed elevation. Original piers do not need to be dismantled, the method is suitable for single-span or multi-span Bailey bridges, construction is fast, the manufacturing cost is low, the working conditions of overflowing and limited space in the flood season can be dealt with, and construction safety and engineering benefits are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of Bailey bridge construction technology, and specifically to a method for jacking up a Bailey bridge. Background Technology

[0002] Bailey bridges, as a type of modular steel structure bridge, consist of single or multiple spans. The piers and pier caps are mostly made of reinforced concrete, and the superstructure is assembled from Bailey panels. With the standardized component design of high-strength steel, they have advantages such as strong interchangeability, fast erection speed, and good economy. They can be adapted to vehicle loads from Class 10 to trailer loads from Class 80 and are widely used in water conservancy and hydropower, road traffic, emergency rescue and other engineering scenarios.

[0003] The construction of existing Bailey bridges often employs the "cantilever push-out method," which involves installing rollers and slabs on both banks of the river. After assembling the main bridge components on the rollers on the pushing bank, the bridge is then pushed to its position on the opposite bank using manual or mechanical traction. However, when Bailey bridges face special conditions requiring upgrades, such as rising water levels during the flood season or increased traffic loads, traditional solutions necessitate the demolition and reconstruction of the original piers or the complete disassembly and reassembly of the bridge truss. This not only results in long construction periods and high project costs but also poses safety risks associated with secondary disassembly and reassembly and the pushing of the bridge. Especially in scenarios involving flowing water or limited space at the bottom, the construction difficulty increases significantly, making it difficult to meet the needs of rapid upgrades and traffic safety.

[0004] Furthermore, traditional construction methods are not well-suited for both single-span and multi-span Bailey bridges. The renovation process can easily damage the structural integrity of the original bridge and cannot simultaneously advance the jacking operation and the construction of new piers, further hindering project efficiency and effectiveness. Therefore, there is an urgent need for a Bailey bridge upgrade and renovation technology that does not require the removal of existing piers, is quick and safe to construct, and is adaptable to various working conditions, in order to address the many pain points of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for jacking up Bailey bridges. This method does not require the removal of the original bridge piers, is suitable for single-span or multi-span Bailey bridges, is quick to construct, has low cost, can cope with flood season flow and confined space conditions, and ensures construction safety and project benefits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a Bailey bridge jacking construction method, comprising the following steps:

[0007] Preparations for S1 construction:

[0008] S101 Material Deployment: Concentrate the construction materials in a designated area 10-20m away from the bridge abutment. When stacking, follow the principle of "first use first, last use last" to ensure convenient hoisting. At the same time, reserve a safe working passage to avoid the stacking of materials from affecting construction access and operational safety.

[0009] S102 Workspace Clearance: Remove part of the bridge deck at the corresponding location of the bridge pier. The removal area should be designed to allow construction personnel to operate jacks for overall jacking operations, ensuring that the operating space is at least 1.2m wide and at least 1.5m high.

[0010] S103 Safety Protection Setup: Install guardrails with a height of not less than 1.2m at the edge of the bridge deck demolition area, and install close-mesh protective netting on the outside of the guardrails. The mesh size of the protective netting should not be greater than 10cm×10cm. Set up a construction scaffold with a load-bearing capacity of not less than 2.5kN / m² on the top surface of the bridge piers, and install guardrails and toe boards around the scaffolds to improve safety protection measures for high-altitude operations.

[0011] S104 Equipment Preparation: Check and place the 100-ton jacks, structural steel, 25# I-beam blocks, measuring instruments, and other materials and tools required for the operation at each jacking position, ensuring that the equipment is in good working order and in sufficient quantity;

[0012] S2: Support System Settings:

[0013] S201 precisely places steel supports at each pier under the Bailey Bridge. The type of steel is determined based on the pier's load-bearing capacity and jacking load. The bottom of the support is flat and fits snugly against the foundation surface.

[0014] S202 places the 100-ton jack stably in the center of the steel support. The bottom surface of the jack is covered with pre-made 25# I-beam blocks. The size of the blocks is not less than 1.2 times the size of the jack base, and the blocks are fixed to the steel support with anti-slip measures.

[0015] S3 synchronous jacking and steel support:

[0016] S301 uses the reserved steps on the bridge piers to position the jacks, and starts the jacks corresponding to the four bridge piers to carry out the Bailey beam lifting operation simultaneously. The lifting process adopts the "stage lifting and real-time monitoring" mode, and the lifting height of each stage is controlled within 50cm.

[0017] During the jacking process of S302, steel supports are used in layers. The specifications of the steel supports are consistent with those of the support system. A layer of steel supports is added every 50cm of jacking to ensure that the supports are firm and not loose.

[0018] S303 monitors the height of each lifting point in real time through measuring instruments to ensure that the deviation of the lifting height of each point does not exceed 20cm. If a deviation occurs, the lifting rate of the jacks will be adjusted in time.

[0019] After the S304 Bailey bridge beam is raised to a temporary safe height, the raising is stopped, and the original supports and abutment plates on the piers are removed one by one and replaced with steel supports of the same specifications for temporary fixation to ensure the stability of the bridge.

[0020] S4 pier heightening concrete pouring:

[0021] S401 When the Bailey bridge is raised to 2m, the jacking is stopped and the formwork is installed in the area where the bridge piers are raised. Steel formwork is used. After installation, ensure that the verticality deviation does not exceed 3‰ and the axis deviation does not exceed 5mm.

[0022] After the S402 template passes the acceptance test, the concrete for raising the bridge pier is poured. The concrete strength grade is not lower than the original bridge pier concrete strength grade. The pouring process adopts a layered pouring method, with each layer not exceeding 50cm in thickness. At the same time, it is vibrated to compact the concrete and avoid quality defects such as honeycomb and pitting.

[0023] After the S403 concrete is poured, it shall be cured in accordance with the specifications for no less than 7 days. The next round of jacking operation can only be carried out after the concrete strength reaches more than 75% of the design strength.

[0024] S404 repeats the lifting, support, pouring, and curing process of steps S3 and S4 until the pier is raised to the design elevation;

[0025] S5 bridge installation and equipment removal:

[0026] S501 After the bridge pier is raised to the design elevation, the top surface of the bridge pier shall be leveled to ensure that the flatness deviation of the bearing installation surface does not exceed 2mm.

[0027] S502 precisely installs the supports and abutment plates on the piers according to the design positions. When installing the supports, ensure that their center line coincides with the pier axis, with a deviation of no more than 3mm.

[0028] S503 slowly lowered the jacks to smoothly place the Bailey bridge onto the newly installed supports. During the placement process, the settlement of the bridge was monitored in real time to ensure uniform settlement.

[0029] After the S504 bridge body was stably seated, the jacks and steel supports above the concrete surface of the piers were removed one by one. The holes left after the supports were removed were repaired to restore the integrity of the bridge piers.

[0030] To further optimize this invention, the following technical solutions may be preferred:

[0031] Preferably, in step S3, the synchronicity deviation of the jacks is controlled within ±5mm, and a unified hydraulic control system is used to realize the synchronous start and stop and pressure adjustment of the four jacks.

[0032] Preferably, it is suitable for single-span or multi-span Bailey bridges. During construction, there is no need to demolish or damage the original bridge piers. The bridge structure is upgraded only by reinforcing and expanding the existing bridge piers and adding new bridge piers. The new bridge piers can be constructed simultaneously with the in-situ bridge deck jacking operation.

[0033] Preferably, when constructing new bridge piers, a truck crane is used for in-situ assembly, eliminating the need for approach bridge installation. The span of the new bridge frame can be set according to project requirements, with a maximum span of 36.676m.

[0034] Preferably, the maximum lifting height of the bridge piers can reach 10m, and the final elevation of the bridge can be raised from the original elevation to the target elevation required by the design, so as to meet the special working conditions such as river flow during the flood season.

[0035] Preferably, in step S4, before pouring the concrete in the area to raise the pier, the laitance and debris on the top surface of the original pier need to be cleaned. If necessary, the top surface of the original pier should be roughened to a depth of not less than 5mm to enhance the bonding strength between the new and old concrete.

[0036] Preferably, the steel components such as steel profiles and I-beam blocks used in the construction process have all undergone rust removal and anti-corrosion treatment, with an anti-corrosion coating thickness of not less than 150μm, to ensure the durability of the components during construction and the temporary support stage.

[0037] The beneficial effects of this invention are:

[0038] (1) This construction method does not require the demolition of the original bridge piers. The Bailey bridge can be upgraded and transformed simply by reinforcing and reinforcing the original bridge piers. This preserves the integrity of the original bridge structure and avoids the waste of resources caused by demolition and reconstruction, thus greatly reducing the project cost. Compared with the traditional solution, it can save more than RMB 2 million.

[0039] (2) The method of synchronous lifting with four jacks and layered steel support is adopted. Combined with real-time monitoring and deviation control, the height difference of the lifting is ensured to be no more than 20cm and the synchronous deviation is controlled within ±5mm. This effectively ensures the stability and safety of the bridge lifting process and completely avoids the risks of secondary disassembly and bridge pushing operations.

[0040] (3) The construction process is standardized and the steps are clear. Every 2m of lifting completes a round of concrete pouring and curing, and the in-situ assembly of new bridge piers can be carried out simultaneously. The maximum lifting height can reach 10m. Compared with the traditional construction method, the construction can be completed more than 15 days earlier, which significantly improves the construction efficiency and meets the timeliness requirements of emergency rescue and flood season protection.

[0041] (4) It has wide adaptability and can be applied to both single-span Bailey bridges and multi-span Bailey bridges. It can cope with complex working conditions in fields such as water conservancy and hydropower, road traffic, and municipal engineering. It is especially suitable for special scenarios such as river flow during the flood season and confined space at the bottom, ensuring smooth traffic on both banks during construction. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating the Bailey bridge jacking construction method of the present invention;

[0043] Figure 2 This is a cross-sectional view of the Bailey Bridge before it was lifted into place;

[0044] Figure 3 This is a cross-sectional view of the Bailey Bridge after it has been lifted into place.

[0045] Figure 4 This is a schematic diagram of the initial jacking structure during construction;

[0046] Figure 5 This is a structural diagram of the bridge pier pouring process during construction;

[0047] Figure 6 This is a structural diagram of the bridge during the second stage of jacking up during construction.

[0048] Figure 7 This is a structural diagram showing the bridge truss in place after the bridge is lifted during construction.

[0049] Among them: 1-pad block, 2-jack, 3-fixed steel reinforcement bar, 4-steel section, 5-bridge pier concrete, 6-formwork, 7-Bailey bridge. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0052] like Figure 1-7 As shown, a method for jacking up a Bailey bridge includes the following steps:

[0053] Preparations for S1 construction:

[0054] S101 Material Deployment: Concentrate the construction materials in a designated area 10-20m away from the bridge abutment. When stacking, follow the principle of "first use first, last use last" to ensure convenient hoisting. At the same time, reserve a safe working passage to avoid the stacking of materials from affecting construction access and operational safety.

[0055] S102 Workspace Clearance: Remove part of the bridge deck at the corresponding location of the bridge pier. The removal area should be designed to allow construction personnel to operate jacks for overall jacking operations, ensuring that the operating space is at least 1.2m wide and at least 1.5m high.

[0056] S103 Safety Protection Setup: Install guardrails with a height of not less than 1.2m at the edge of the bridge deck demolition area, and install close-mesh protective netting on the outside of the guardrails. The mesh size of the protective netting should not be greater than 10cm×10cm. Set up a construction scaffold with a load-bearing capacity of not less than 2.5kN / m² on the top surface of the bridge piers, and install guardrails and toe boards around the scaffolds to improve safety protection measures for high-altitude operations.

[0057] S104 Equipment Preparation: Check and place the 100-ton jacks, structural steel, 25# I-beam blocks, measuring instruments, and other materials and tools required for the operation at each jacking position, ensuring that the equipment is in good working order and in sufficient quantity;

[0058] S2: Support System Settings:

[0059] S201 precisely places steel supports at each pier under the Bailey Bridge. The type of steel is determined based on the pier's load-bearing capacity and jacking load. The bottom of the support is flat and fits snugly against the foundation surface.

[0060] S202 places the 100-ton jack stably in the center of the steel support. The bottom surface of the jack is covered with pre-made 25# I-beam blocks. The size of the blocks is not less than 1.2 times the size of the jack base, and the blocks are fixed to the steel support with anti-slip measures.

[0061] S3 synchronous jacking and steel support:

[0062] S301 uses the reserved steps on the bridge pier to position jack 2, and starts the jacks corresponding to the four bridge piers to carry out the Bailey beam lifting operation simultaneously. The lifting process adopts the "stage lifting and real-time monitoring" mode, and the lifting height of each stage is controlled within 50cm.

[0063] During the jacking process of S302, steel supports are used in layers. The specifications of the steel supports are consistent with those of the support system. A layer of steel supports is added every 50cm of jacking to ensure that the supports are firm and not loose.

[0064] S303 monitors the height of each lifting point in real time through measuring instruments to ensure that the deviation of the lifting height of each point does not exceed 20cm. If a deviation occurs, the lifting rate of the jacks will be adjusted in time.

[0065] After the S304 Bailey bridge beam is raised to a temporary safe height, the raising is stopped, and the original supports and abutment plates on the piers are removed one by one and replaced with steel supports of the same specifications for temporary fixation to ensure the stability of the bridge.

[0066] S4 pier heightening concrete pouring:

[0067] S401 When the Bailey bridge is raised to 2m, the jacking is stopped and the formwork is installed in the area where the bridge piers are raised. Steel formwork is used. After installation, ensure that the verticality deviation does not exceed 3‰ and the axis deviation does not exceed 5mm.

[0068] After the S402 template passes the acceptance test, the concrete for raising the bridge pier is poured. The concrete strength grade is not lower than the original bridge pier concrete strength grade. The pouring process adopts a layered pouring method, with each layer not exceeding 50cm in thickness. At the same time, it is vibrated to compact the concrete and avoid quality defects such as honeycomb and pitting.

[0069] After the S403 concrete is poured, it shall be cured in accordance with the specifications for no less than 7 days. The next round of jacking operation can only be carried out after the concrete strength reaches more than 75% of the design strength.

[0070] S404 repeats the lifting, support, pouring, and curing process of steps S3 and S4 until the pier is raised to the design elevation;

[0071] S5 bridge installation and equipment removal:

[0072] S501 After the bridge pier is raised to the design elevation, the top surface of the bridge pier shall be leveled to ensure that the flatness deviation of the bearing installation surface does not exceed 2mm.

[0073] S502 precisely installs the supports and abutment plates on the piers according to the design positions. When installing the supports, ensure that their center line coincides with the pier axis, with a deviation of no more than 3mm.

[0074] S503 slowly lowered the jacks to smoothly place the Bailey bridge onto the newly installed supports. During the placement process, the settlement of the bridge was monitored in real time to ensure uniform settlement.

[0075] After the S504 bridge body was stably seated, the jacks and the steel supports above the concrete surface of the piers were removed one by one. The holes left after the supports were removed were repaired to restore the integrity of the bridge piers.

[0076] In a preferred embodiment, in step S3, the synchronicity deviation of the jacks is controlled within ±5mm, and a unified hydraulic control system is used to realize the synchronous start and stop and pressure adjustment of the four jacks.

[0077] As a preferred implementation method, it is applicable to single-span or multi-span Bailey bridges. During construction, there is no need to demolish or damage the original piers. The bridge structure is upgraded only by reinforcing and expanding the existing piers and adding new piers. The new piers can be constructed simultaneously with the in-situ bridge deck jacking operation.

[0078] As a preferred implementation method, when constructing new bridge piers, a truck crane is used for in-situ assembly, eliminating the need for approach bridge installation. The span of the new bridge frame can be set according to project requirements, with a maximum span of 36.676m.

[0079] As a preferred implementation method, the maximum lifting height of the bridge pier raising construction can reach 10m, and the final elevation of the bridge body can be raised from the original elevation to the target elevation required by the design, so as to meet the special working conditions such as river flow during the flood season.

[0080] As a preferred embodiment, in step S4, before pouring the pier heightening area, the laitance and debris on the top surface of the original pier need to be cleaned. If necessary, the top surface of the original pier should be roughened to a depth of not less than 5mm to enhance the bonding strength between the new and old concrete.

[0081] As a preferred embodiment, the steel supports and I-beam blocks used in the construction process are all rust-removed and corrosion-resistant, with an anti-corrosion coating thickness of not less than 150μm, to ensure the durability of the components during construction and the temporary support stage.

[0082] This embodiment uses the Bailey Bridge upgrade and renovation project as an application scenario. The Bailey Bridge is a three-span structure with an original elevation of EL99.10m. Due to the need for river flow during the flood season, the bridge elevation needs to be raised to 110.0m. Simultaneously, a new pier and a 36.676m span bridge structure are added to the left of the original piers, and unimpeded traffic on both banks must be maintained during construction. This project adopts the Bailey Bridge jacking construction method of this invention, and the specific implementation steps are as follows:

[0083] I. Pre-construction preparations

[0084] (1) Material deployment: The materials required for construction, such as steel sections, 25# I-beams, concrete raw materials, bearings, and bridge abutment plates, are piled up in a designated flat area 15m away from the bridge abutment. When piling up, the principle of "first use first, then pile up" is strictly followed. Steel components and concrete raw materials are piled up separately, and a safe working passage with a width of not less than 1.5m is reserved to ensure that the crane lifting operation is convenient and does not affect the construction passage.

[0085] (2) Clearing the working space: Remove the bridge deck at the corresponding position of each pier. The removal range shall be carried out in accordance with the standard of 1.3m width and 1.6m height of the operating space to ensure that there is no space obstruction when the construction personnel operate the jacks, and at the same time avoid excessive removal that may affect the temporary stability of the bridge.

[0086] (3) Safety protection setup: Install a 1.3m high guardrail at the edge of the bridge deck demolition area. The guardrail is made of Φ48mm steel pipe with a spacing of 1.5m. A dense protective net with a mesh size of 8cm×8cm is laid on the outside of the guardrail. A construction basket with a load-bearing capacity of 3kN / m² is set on the top surface of each pier. The basket frame is made of welded steel. A 1.2m high guardrail and an 18cm high toe board are set around the basket. Anti-slip steel plate is laid at the bottom of the basket to ensure the safety of high-altitude operations.

[0087] (4) Equipment preparation: At the lifting positions of the four piers, count and place 100-ton hydraulic jacks, matching steel supports, prefabricated 25# I-beam pads (the size of which is 1.3 times the size of the jack base), level instruments, total stations and other tools. Conduct pressure tests on the jacks to ensure that their performance is intact. The measuring instruments are calibrated and qualified. The quantity of all tools meets the construction requirements.

[0088] II. Support System Setup

[0089] (1) Based on the calculation results of the pier bearing and jacking load of the project, H-beams were selected as support components. Steel supports were precisely placed at the four piers under the Bailey Bridge. The bottom of the support was leveled with cement mortar to ensure that it was flat and in close contact with the foundation, and the fit deviation was no more than 2mm.

[0090] (2) Place the 100-ton jack stably in the center of the steel support. Lay a pre-processed 25# I-beam pad 1 on the bottom surface of the jack. Lay an anti-slip rubber pad between the pad and the steel support to prevent the jack from shifting during the lifting process.

[0091] III. Synchronous Lifting and Steel Support

[0092] (1) The jacks are precisely positioned by using the reserved steps on the piers. A unified hydraulic control system is used to connect the jacks of the four piers to achieve synchronous start-stop and pressure adjustment, ensuring that the synchronous deviation is controlled within ±5mm. The jacking process adopts the "staged jacking and real-time monitoring" mode, with each stage of jacking height controlled at 40cm to avoid uneven stress on the bridge body caused by excessive jacking in a single operation.

[0093] (2) For every 40cm of jacking, add a layer of steel support pads that are consistent with the specifications of the support system. The joints of the support pads are fixed with bolts to ensure that the support pads are firm and not loose, forming a stable temporary support system.

[0094] (3) During the jacking process, the height of each jacking point is monitored in real time by a level and a total station. Data is recorded every 10cm of jacking to ensure that the jacking height deviation of each point does not exceed 20cm. If a deviation occurs, the jacking rate of the corresponding jack is adjusted through the hydraulic control system until the deviation is corrected.

[0095] (4) When the Bailey beam is raised to a temporary safe height (30cm higher than the top surface of the original support), the raising is suspended. The construction personnel use the construction basket to remove the original supports and bridge seat plates on the piers one by one and replace them with steel supports of the same specification for temporary fixation to ensure that the bridge remains stable in subsequent construction.

[0096] IV. Concrete pouring for pier heightening

[0097] (1) When the Bailey Bridge 7 is raised to 2m, the jacking is stopped and the steel formwork is installed in the area where the pier is raised. After the formwork 6 is installed, it is corrected by a total station to ensure that the verticality deviation does not exceed 3‰ and the axis deviation does not exceed 5mm. The joints of the formwork are sealed with sealant to prevent grout leakage.

[0098] (2) After the template is accepted, the top surface of the original pier is roughened to a depth of 6mm. The laitance and debris are cleaned and the surface is moistened with water. Then, the pier heightening concrete is poured. The concrete strength grade is one grade higher than that of the original pier concrete (the original pier is C30, and this embodiment uses C35). The pouring process adopts a layered pouring method, with each layer being 40cm thick. An immersion vibrator is used to compact the concrete. The vibration time is controlled at 20-30s / point to avoid quality defects such as honeycomb and pitted surface.

[0099] (3) After the concrete is poured, cover it with geotextile and water it for curing. The curing time is 10 days. The strength is tested by concrete test blocks. The next round of jacking operation can only be carried out after the strength reaches 80% of the design strength.

[0100] (4) Repeat the above synchronous jacking, steel support, formwork installation, concrete pouring and curing process for a total of 5 cycles of operation, and finally raise the pier to the design elevation of 110.0m. During this process, the in-situ assembly of the new pier and the 36.676m bridge frame is carried out simultaneously. The components are lifted by truck crane, the approach bridge installation process is eliminated, and the construction period is shortened.

[0101] V. Bridge Deployment and Equipment Removal

[0102] (1) When the pier is raised to the design elevation of 110.0m, the top surface of the pier is leveled. A cement mortar leveling layer with a thickness of 5cm is used to ensure that the flatness deviation of the bearing installation surface does not exceed 2mm.

[0103] (2) Install the supports and bridge seat plates on the piers precisely according to the design position. When installing the supports, use a total station to position them to ensure that their center line coincides with the axis of the pier and the deviation does not exceed 3mm. Use epoxy resin mortar to level the bottom of the supports and the top surface of the pier.

[0104] (3) Start the hydraulic control system and slowly lower the jack at a rate of 10 cm / h to smoothly place the Bailey bridge on the newly installed support. During the placement process, monitor the settlement of the bridge body in real time with a level to ensure uniform settlement and a settlement difference of no more than 5 mm.

[0105] (4) After the bridge body is stably seated (no abnormal settlement after 24 hours of static placement), the jacks and steel supports above the concrete surface of the piers are removed one by one. The holes after the supports are removed are repaired with C35 micro-expansion concrete to restore the integrity of the pier appearance.

[0106] In this embodiment, the three-span Bailey bridge was simultaneously jacked up, with a maximum jacking height of 10 meters. The construction of new bridge piers was synchronized with the jacking up of existing piers, completing the construction plan 15 days ahead of schedule and saving 2 million yuan in project investment. During the flood season from November 2020 to May 2021, the river's flow level exceeded the original height of the Bailey bridge. The raised Bailey bridge operated stably, effectively ensuring smooth traffic on both banks and achieving significant economic and social benefits.

[0107] The construction method of the present invention is not only applicable to the renovation of the three-span Bailey bridge in this embodiment, but also applicable to the lifting and raising of the single-span Bailey bridge. It can be widely used in water conservancy and hydropower, road traffic, emergency rescue, municipal engineering and other fields, and is especially suitable for Bailey bridge upgrade and renovation projects under the conditions of river flow during the flood season and confined space at the bottom.

[0108] The above description is an embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A method for constructing a Bailey bridge by jacking, characterized in that, Includes the following steps: Preparations for S1 construction: S101 Material Deployment: Concentrate the construction materials in a designated area 10-20m away from the bridge abutment. When stacking, follow the principle of "first use first, last use last" to ensure convenient hoisting. At the same time, reserve a safe working passage to avoid the stacking of materials from affecting construction access and operational safety. S102 Workspace Clearance: Remove part of the bridge deck at the corresponding location of the bridge pier. The removal area should be designed to allow construction personnel to operate jacks for overall jacking operations, ensuring that the operating space is at least 1.2m wide and at least 1.5m high. S103 Safety Protection Setup: Install guardrails with a height of not less than 1.2m at the edge of the bridge deck demolition area, and install close-mesh protective netting on the outside of the guardrails. The mesh size of the protective netting should not be greater than 10cm×10cm. Set up a construction scaffold with a load-bearing capacity of not less than 2.5kN / m² on the top surface of the bridge piers, and install guardrails and toe boards around the scaffolds to improve safety protection measures for high-altitude operations. S104 Equipment Preparation: Check and place the 100-ton jacks, structural steel, 25# I-beam blocks, measuring instruments, and other materials and tools required for the operation at each jacking position, ensuring that the equipment is in good working order and in sufficient quantity; S2: Support System Settings: S201 precisely places steel supports at each pier under the Bailey Bridge. The type of steel is determined based on the pier's load-bearing capacity and jacking load. The bottom of the support is flat and fits snugly against the foundation surface. S202 places the 100-ton jack stably in the center of the steel support. The bottom surface of the jack is covered with pre-made 25# I-beam blocks. The size of the blocks is not less than 1.2 times the size of the jack base, and the blocks are fixed to the steel support with anti-slip measures. S3 synchronous jacking and steel support: S301 uses the reserved steps on the bridge piers to position the jacks, and starts the jacks corresponding to the four bridge piers to carry out the Bailey beam lifting operation simultaneously. The lifting process adopts the "stage lifting and real-time monitoring" mode, and the lifting height of each stage is controlled within 50cm. During the jacking process of S302, steel supports are used in layers. The specifications of the steel supports are consistent with those of the support system. A layer of steel supports is added every 50cm of jacking to ensure that the supports are firm and not loose. S303 monitors the height of each lifting point in real time through measuring instruments to ensure that the deviation of the lifting height of each point does not exceed 20cm. If a deviation occurs, the lifting rate of the jacks will be adjusted in time. S304 After the Bailey beam is lifted to a temporary safe height, the lifting is stopped, and the original supports and abutment plates on the piers are removed one by one and replaced with steel supports of the same specification for temporary fixation to ensure the stability of the bridge. S4 pier heightening concrete pouring: S401 When the Bailey bridge is raised to 2m, the jacking is stopped and the formwork is installed in the area where the bridge piers are raised. Steel formwork is used. After installation, ensure that the verticality deviation does not exceed 3‰ and the axis deviation does not exceed 5mm. After the S402 template passes the acceptance test, the concrete for raising the bridge pier is poured. The concrete strength grade is not lower than the original bridge pier concrete strength grade. The pouring process adopts a layered pouring method, with each layer not exceeding 50cm in thickness. At the same time, it is vibrated to compact the concrete and avoid quality defects such as honeycomb and pitting. After the S403 concrete is poured, it shall be cured in accordance with the specifications for no less than 7 days. The next round of jacking operation can only be carried out after the concrete strength reaches more than 75% of the design strength. S404 repeats the lifting, support, pouring, and curing process of steps S3 and S4 until the pier is raised to the design elevation; S5 bridge installation and equipment removal: S501 After the bridge pier is raised to the design elevation, the top surface of the bridge pier shall be leveled to ensure that the flatness deviation of the bearing installation surface does not exceed 2mm. S502 precisely installs the supports and abutment plates on the piers according to the design positions. When installing the supports, ensure that their center line coincides with the pier axis, with a deviation of no more than 3mm. S503 slowly lowered the jacks to smoothly place the Bailey bridge onto the newly installed supports. During the placement process, the settlement of the bridge was monitored in real time to ensure uniform settlement. After the S504 bridge body was stably seated, the jacks and steel supports above the concrete surface of the piers were removed one by one. The holes left after the supports were removed were repaired to restore the integrity of the bridge piers.

2. The Bailey bridge jacking construction method according to claim 1, characterized in that, In step S3, the synchronization deviation of the jacks is controlled within ±5mm, and a unified hydraulic control system is used to realize the synchronous start and stop and pressure adjustment of the four jacks.

3. The Bailey bridge jacking construction method according to claim 1, characterized in that, It is suitable for single-span or multi-span Bailey bridges. During construction, there is no need to demolish or damage the original piers. The bridge structure is upgraded by reinforcing and expanding the existing piers and adding new piers. The new piers can be constructed simultaneously with the in-situ bridge deck jacking operation.

4. The Bailey bridge jacking construction method according to claim 3, characterized in that, When constructing new bridge piers, a truck crane is used for in-situ assembly, eliminating the need for approach bridge installation. The span of the new bridge frame can be set according to project requirements, with a maximum span of 36.676m.

5. The Bailey bridge jacking construction method according to claim 1, characterized in that, The maximum lifting height of the bridge piers can reach 10m, and the final elevation of the bridge can be raised from the original elevation to the target elevation required by the design, meeting the needs of special working conditions such as river flow during the flood season.

6. The Bailey bridge jacking construction method according to claim 1, characterized in that, In step S4, before pouring the concrete in the area where the pier is heightened, the laitance and debris on the top surface of the original pier must be cleaned. If necessary, the top surface of the original pier should be roughened to a depth of not less than 5mm to enhance the bonding strength between the new and old concrete.

7. The Bailey bridge jacking construction method according to claim 1, characterized in that, All steel components used in the construction process, such as steel profiles and I-beam blocks, have undergone rust removal and anti-corrosion treatment, with an anti-corrosion coating thickness of not less than 150μm, to ensure the durability of the components during construction and temporary support phases.

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