Construction method for maintaining and reinforcing old bridge

Abstract

The invention relates to the technical field of old bridge maintenance, in particular to an old bridge maintenance and reinforcement construction method which comprises the specific steps that S1, a protection system is laid, the structure state is monitored in real time in the construction process, and shutdown adjustment is conducted immediately when hidden dangers are found; s2, repairing the hinge joint, wherein the hinge joint is chiseled away, steel bars are planted, hinge joint concrete is poured, and concrete is paved; s3, the beam plate is replaced, and appearance inspection and quality acceptance are conducted on the replaced beam plate; s4, bridge jacking and support replacement are conducted, a hydraulic synchronous jacking system is erected and comprises a jacking system, a monitoring system and a temporary supporting system, and multi-point synchronous jacking of a beam body is achieved through control of a PLC computer; s5, completion acceptance is carried out; a protection system and a limiting steel truss are arranged and used for limiting transverse displacement in the bridge jacking process and reducing the bridge instability risk, meanwhile, a beam body posture safety monitoring facility is arranged and used for monitoring the beam body posture, and when abnormity occurs, an early warning mechanism is triggered, and construction safety is ensured.

Description

Technical Field

[0001] This invention relates to the field of old bridge maintenance technology, and in particular to a construction method for the maintenance and reinforcement of old bridges. Background Technology

[0002] With the continuous increase in traffic volume, the number of heavy vehicles has increased, and overloading has become a serious problem, leading to an increase in cases of oversized and overweight transport. Bridges built in the past bear extremely heavy traffic loads. Over time, these bridges have developed various defects and require repair and reinforcement.

[0003] In existing technologies, the repair and reinforcement construction scheme uses a high-precision hydraulic synchronous system to control the lifting of the bridge and replace the bearings. The status of each jack is monitored in real time by computer, and the eccentric load is automatically balanced to maintain synchronous and stable lifting. However, the quality of old bridges is uncontrollable, with various defects and hidden dangers, poor stability, and most bridge construction requires high-altitude operations, which are high-risk and may lead to sudden accidents during construction. Existing construction methods lack corresponding safety monitoring and protection measures, which affect the safety of old bridge repair and construction. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for the repair and reinforcement of old bridges.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for repairing and reinforcing an old bridge, the specific steps of which include: S1. Install a protection system to monitor the structural status in real time during construction, and immediately stop work and make adjustments if any hidden dangers are found. S2. Joint repair, including joint removal, rebar installation, pouring joint concrete, and paving concrete. The construction sequence for rebar installation is as follows: positioning, drilling, hole cleaning, steel rust removal, rebar adhesive preparation, rebar installation, curing, protection, inspection and acceptance. S3. Beam and slab replacement: visual inspection and quality acceptance of the replaced beams and slabs. S4. Bridge jacking and bearing replacement: Erect a hydraulic synchronous jacking system, including a jacking system, a monitoring system and a temporary support system, and achieve multi-point synchronous jacking of the beam through PLC computer control. The jacking process includes construction preparation, commissioning and installation of the jacking system, installation of the monitoring system, pre-jacking, formal jacking, construction of new support pads and beam bottom wedges, support replacement, beam lowering, dismantling of jacking equipment, and site cleanup. S5. Final acceptance and load-bearing capacity testing: Verify whether the reinforced bridge meets the design requirements through static or dynamic load tests.

[0006] Preferably, in step S1, the protection system includes a safety protection platform and a beam posture safety monitoring facility. The safety protection platform includes a lifting platform and a limiting steel truss. The lifting platform includes an operating platform, a scissor lift, and a movable base. The limiting steel truss is installed on both sides of the bridge and is fixedly connected to the ground through a pre-embedded base. One end of the operating platform is provided with a sliding seat, and the limiting steel truss is provided with a slide rail corresponding to the sliding seat. The beam posture safety monitoring facility includes displacement sensors, tilt sensors, and environmental monitoring sensors. The displacement sensors include laser rangefinders, total stations, GPS devices, and wire displacement gauges. The tilt sensors include electronic levels, inclinometers, and gyroscopes. The environmental monitoring sensors include ambient temperature sensors, wind speed sensors, and vibration sensors.

[0007] Preferably, in step S2, the rebar installation step includes: a1. Positioning: Mark the drilling location and model according to design requirements; a2. Drilling: Use an electric hammer or pneumatic drill to drill holes. If you encounter reinforcing bars, adjust the hole position to avoid them. Wash the debris inside the hole with clean water and dry it. The hole diameter is d+4~8mm. The hole depth should not be set inside the protective layer or decorative layer of the component. a3. Clean the hole. After drilling, check that the hole depth and diameter are within acceptable limits. Blow out the dust inside the hole with compressed air, then clean the hole wall with a brush and cotton cloth. Blow the hole again with compressed air, repeating this process 3 to 5 times until there is no dust or debris inside the hole. Finally, wipe the hole wall clean with a cotton cloth soaked in acetone and temporarily seal the hole opening. If there are any unusable holes, fill them with anchoring adhesive after cleaning. Keep the drilled hole dry. a4. Remove rust from steel materials, thoroughly cleaning away rust and oil stains within the anchoring length of the steel materials; a5. Rebar installation: Prepare the rebar installation adhesive according to the ratio, stir it evenly, and inject it into the hole using an injection gun. The amount of rebar installation adhesive should generally be 2 / 3 of the hole depth, and a small amount of adhesive should overflow around the rebar after it is inserted. Immediately after injecting the anchoring adhesive, rotate the inserting rebar in one direction until the designed depth is reached, ensuring that the gap between the inserted rebar and the hole wall is uniform, and correcting the position and verticality of the rebar. a6. Curing and protection: The reinforcing bars must not be disturbed during the curing process of the adhesive. If there is significant disturbance, the reinforcing bars must be re-installed. a7. Inspection and acceptance: Randomly sample and inspect 3-4 days after rebar installation. Perform a pull-out test on the system consisting of jacks, anchors, and reaction frames.

[0008] Preferably, in step S2, the following steps are performed: pouring the hinge joint concrete and paving the concrete: after the anchoring adhesive has cured, the hinge joint is rinsed and moistened with a high-pressure water gun, the bottom of the hinge joint is sealed with foam board, and cement mortar with the same mix ratio as the hinge joint concrete is laid. The shear bars and longitudinal reinforcing bars are placed in the hinge joint, fiber concrete is poured, and a vibrator is inserted to compact it. After the concrete has set, it is immediately covered with non-woven geotextile and watered for curing.

[0009] Preferably, in step S4, the bridge jacking and bearing replacement steps are as follows: B1. Construction preparation; B2. Commissioning and installation of the lifting system; B3. Installation of the monitoring system; B4. Pre-lifting; B5. Formal jacking is completed in multiple stages. After each stage of jacking is completed, the temporary supports should be adjusted in a timely manner to ensure that their top surfaces are in close contact with the bottom of the beam. B6. Construction of new support pad stones and beam bottom wedge blocks; B7. Replacement of bearing; B8. Lowering the beam; The beam lowering procedure is the reverse of the jacking procedure. Before lowering the beam, confirm that all temporary supports have been removed and steel pads have been installed. After the beam is lowered to the support point to bear the load, pay attention to the data shown by the displacement and pressure sensors to ensure that the deceleration and displacement changes of each pier are consistent. If the difference is too large, find out the cause and deal with it before lowering the beam again. B9. Dismantle the lifting equipment and clean up the site.

[0010] Preferably, in step B1, the construction preparation is as follows: a temporary steel bracket is installed on the side of the cap beam below the outer support of the bridge pier side beam at the discontinuous section; the upper and lower base surfaces of the remaining pier cap beams or cap jacks and temporary supports are cleaned; the protruding parts of the base surface are chiseled off; and the broken and loose concrete debris is removed so that the base surface is in a horizontal state. Before jacking, the expansion joints of the entire bridge must be removed to ensure that the replacement of the bearings does not affect the structure of the adjacent spans. The old bridge deck asphalt concrete must be milled first, and the outer guardrails must be cut with a water jet. The erected jacking support must be inspected to ensure that it has sufficient strength, rigidity and stability. The mid-span deflection of the support must be less than 10mm to ensure that the support does not collapse or tilt when the beam is jacked up, and that the settlement is small and uniform. Before jacking, the anti-lateral displacement device and the limiting device should be carefully checked. In step B2, the commissioning and installation of the jacking system: the jacking system adopts dual control of displacement and jacking pressure as the basis for jacking control. External data acquisition uses electronic displacement sensors for displacement acquisition and pressure sensors for pressure acquisition. Before that, the normal operation of each control system should be individually and uniformly debugged. In step B3, the monitoring system is installed: the monitoring system is a supporting device for the jacking system, including pressure sensors, displacement sensors, and dial gauges; Displacement sensors are installed near the support jacks to accurately reflect the displacement during the lifting process; pressure sensors are installed in conjunction to accurately reflect the pressure values ​​borne by the jacks; dial gauges should also be installed on the bottom plate of the beam as auxiliary displacement control and correction measures.

[0011] Preferably, in step B4, the main purpose of pre-lifting is to eliminate potential problems in the lifting system, such as oil leakage at the oil line joints or insufficient oil pump pressure, while also eliminating potential inelastic deformation during the lifting process. Pre-lifting is controlled by jacking the beam to the design load. It is necessary to ensure that the beam is lifted synchronously during the lifting process and the load should be held for more than 5 minutes before unloading. After unloading, the control systems and appearance of the system should be carefully checked. The key points of the inspection include: whether there is any oil leakage in all oil circuits, whether there is any abnormality in the jacks, and the appearance of wear on the power supply lines. After unloading, carefully check the upper and lower steel plates of the jack for any deformation. If necessary, adjust the thickness of the steel plates to meet the lifting requirements. Carefully check the structure under the jack's placement position for any differences from before lifting. If any are found, the cause must be thoroughly investigated before formal lifting can begin. Lifting must not be carried out if the situation is unclear.

[0012] Preferably, in step B6, after confirming on-site that the jacking height has reached the design requirements, the old support is removed, the original support pad is chiseled away, and a new support pad is poured to ensure that the top surface of the support pad and the bottom surface of the wedge block remain horizontal; the original embedded steel plate on the upper part of the support should be ground and rust removed until it has a metallic luster, and the surrounding local concrete should be roughened. Then, the galvanized steel plate should be leveled by using structural adhesive, and then the new support should be installed. When the embedded steel plate is not level with the concrete at the bottom of the beam, appropriate treatment should be carried out after the original support is removed from the beam. Unevenness between the embedded steel plate and the concrete at the bottom of the beam can easily lead to damage to the support edge. The protruding concrete needs to be chiseled away to ensure that it is flush with the embedded steel plate.

[0013] Preferably, in step B7, during the installation of the support, it is necessary to prevent the support from being subjected to eccentric pressure or excessive initial shear deformation. After the installation is completed, it must be ensured that the support is in close contact with the upper and lower structures, and there must be no gaps. After the supports are installed, conduct a comprehensive inspection to check whether any supports are missing, whether the support installation direction and type are correct, to ensure the normal operation of the supports after installation, and record any deviations and abnormalities that occur after the supports are installed.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The jacking system of this invention is equipped with a corresponding monitoring system to monitor the construction status in real time. It uses displacement closed-loop control theory, takes displacement as the control object, realizes force and position dual control, ensures that the synchronous error of each jacking point is less than the bridge failure limit, and ensures that the bridge jacking is synchronous and stable. 2. This invention is equipped with a protection system. The lifting platform is used for construction personnel to safely climb and operate at height, and facilitates the installation and wiring of sensors and jacks. The limiting steel truss is used to limit the lateral displacement during the bridge jacking process, reducing the risk of bridge instability. At the same time, a beam posture safety monitoring facility is set up to monitor the beam posture. When an abnormality occurs, an early warning mechanism is triggered to stop construction and remind construction personnel to avoid or adjust the situation, ensuring construction safety. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the safety protection platform under construction status involved in the old bridge repair and reinforcement construction method proposed in this invention; Figure 2 This is a right-side sectional view of the safety protection platform under construction status, which is part of the old bridge repair and reinforcement construction method proposed in this invention. Figure 3 This is a three-dimensional structural diagram of the safety protection platform involved in the old bridge repair and reinforcement construction method proposed in this invention.

[0016] In the diagram: 1. Bridge beam; 2. Abutment; 3. Limiting steel truss; 31. Embedded base; 32. Protective sliding plate; 4. Lifting platform; 41. Operating platform; 410. Anti-collision block; 411. Passage gate; 412. Sensor mounting base; 42. Scissor lift; 43. Moving base; 44. Slide seat; 5. Cap beam; 6. Pier column; 7. Jack; 8. Temporary support. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Reference Figure 1-3 A method for repairing and reinforcing an old bridge, the specific steps of which include: S1. Install a protection system to monitor the structural status in real time during construction, and immediately stop work and make adjustments if any hidden dangers are found. The protection system includes a safety protection platform and beam posture safety monitoring facilities. The safety protection platform includes a lifting platform 4 and a limiting steel truss 3. The lifting platform 4 includes an operating platform 41, a scissor lift 42, and a movable base 43. The limiting steel truss 3 is set on both sides of the bridge to limit the lateral displacement of the bridge during the jacking process and ensure the structural safety of the bridge during the jacking process. The limiting steel truss 3 is fixedly connected to the ground through the pre-embedded base 31. As needed, cables can be set around the limiting steel truss 3 to improve the stability of the limiting steel truss 3 and ensure that the limiting steel truss 3 is set vertically. One end of the operating platform 41 is provided with a slide seat 44. The limiting steel truss 3 is provided with a slide rail corresponding to the slide seat 44. The scissor lift 42 controls the lifting and lowering of the operating platform 41. The limiting steel truss 3 is slidably connected through the slide seat 44 to improve the stability of the operating platform 41 and improve the safety of construction personnel. A ladder can be set on the limiting steel truss 3 to facilitate the up and down of construction personnel. In addition, the operating platforms 41 can be connected by bolts, and anti-collision blocks 410 are set at the contact points of the operating platforms 41. Multiple operating platforms 41 form a whole, which improves the limiting reliability of the limiting steel trusses 3 on both sides of the bridge. A protective sliding plate 32 is set near the beam 1 of the limiting steel truss 3 to protect the surface of the beam 1 and avoid damage caused by collision. At the same time, a pressure sensor can be set inside the protective sliding plate 32 to detect the lateral pressure generated during the lifting of the beam 1 and ensure that the lifting of the beam 1 is stable and reliable. The lifting platform 4 and the limiting steel truss 3 form a safety protection frame. If the bridge tilts or collapses, the limiting steel truss 3 guides it to tilt inward, and the lifting platform 4 supports the beam 1, reducing the accident area and improving the reliability of safety protection. At the same time, the side frame of the operating platform 41 is made of high-strength pipes welded together. If an accident occurs, personnel can hide inside the operating platform 41 to reduce the risk of injury. A passage door 411 is provided at the contact point of the control panel 41 to facilitate the movement of construction personnel. The control panel 41 is equipped with a sensor mounting base 412 to facilitate the installation and arrangement of the devices and sensors used in the beam posture safety monitoring facility, to monitor the beam at close range, or to facilitate the wiring of the jack 7 and sensors, thereby improving the equipment installation efficiency. The beam posture safety monitoring facilities include displacement sensors, tilt sensors, and environmental monitoring sensors. The displacement sensors include laser rangefinders, total stations, GPS, and wire displacement gauges, which monitor the vertical and horizontal displacement of beam 1, providing data for controlling the jacking system. The tilt sensors include electronic levels, inclinometers, and gyroscopes, which monitor the overall and local tilt of beam 1. The environmental monitoring sensors include ambient temperature sensors, wind speed sensors, and vibration sensors. The ambient temperature sensors monitor the ambient temperature and analyze the impact of temperature changes on bridge displacement and stress; temperature compensation can improve the accuracy of monitoring data. The wind speed and vibration sensors are used in windy or vibrating environments to monitor wind speed and structural vibration, assess the impact of external loads on the jacking process, and prevent bridge instability or monitoring equipment failure due to wind vibration.

[0019] S2. Joint repair, including joint removal, rebar installation, pouring joint concrete, and paving concrete. A1. Removal of hinge joint: Remove the original bridge deck concrete pavement. When removing the old bridge pavement layer, retain at least 10d length of pavement layer steel bars (10d length is 10 times the diameter of the steel bars), weld them to the new pavement layer steel bars, and then cut off the original hinge joint shear steel bars on both sides of the hinge joint. The concrete inside the hinge joint is broken up using high-pressure water jetting, and the broken concrete blocks are removed. During maintenance, a colored tarpaulin is suspended from the lower part of the hinge joint using a lifting work platform 4 to prevent the removed concrete debris and cement slurry that precipitated during pouring from falling into the river or onto the road. In order to delay the formation of a through joint between the hinge joint concrete and the hollow slab beam, the surface of the hollow slab beam on both sides of the hinge joint needs to be roughened using a roughening machine to enhance the bonding force between the old and new concrete.

[0020] A2. Rebar installation: The construction sequence for rebar installation is as follows: positioning, drilling, hole cleaning, steel rust removal, rebar adhesive preparation, rebar installation, curing, protection, inspection and acceptance. a1. Positioning: Mark the drilling location and model according to design requirements; a2. Drilling: Drilling should be done with an electric hammer or pneumatic drill. If you encounter steel bars, adjust the hole position to avoid them. If you use a water drill (coring machine) to drill, wash the debris in the hole with clean water and dry it. The borehole diameter is d+4~8mm (the lower value is used for small diameter steel bars and the higher value is used for large diameter steel bars, where d is the diameter of the steel bar or bolt); the borehole depth should not be set within the protective layer or decorative layer of the component; a3. Clean the hole. After drilling, check that the hole depth and diameter are within acceptable limits. Blow out the dust inside the hole with compressed air, then clean the hole wall with a brush and cotton cloth. Blow the hole again with compressed air. Repeat this process 3 to 5 times until there is no dust or debris inside the hole. Finally, wipe the hole wall clean with a cotton cloth soaked in acetone and temporarily seal the hole opening. If there are any unusable holes, fill them with anchoring adhesive after cleaning. The inside of the drilled hole should be kept dry. a4. Rust removal from steel: Rust and oil stains within the anchorage length of steel should be thoroughly removed, and the bluish oxide scale on new reinforcing bars and bolts should also be removed. a5. Rebar installation: Prepare the rebar installation adhesive according to the ratio, stir it evenly, and inject it into the hole using an injection gun. The amount of rebar installation adhesive should generally be 2 / 3 of the hole depth, and a small amount of adhesive should overflow around the rebar after it is inserted. After injecting the anchoring adhesive, the reinforcing bar should be inserted into the hole by rotating it in one direction until the designed depth is reached. Ensure that the gap between the inserted reinforcing bar and the hole wall is basically uniform and correct the position and verticality of the reinforcing bar. Alternatively, the reinforcing bar can be inserted into the hole by hammering it with a hand hammer. When hammering, one hand should hold the reinforcing bar or bolt to ensure centering and prevent rebound. a6. Curing and protection: The anchoring adhesive has a curing process. Generally, the anchoring bars should not be disturbed within 12 hours when the average daily temperature is above 25℃, and should not be disturbed within 24 hours when the average daily temperature is below 25℃. If there is a large disturbance, the anchoring should be re-installed. The anchoring adhesive can cure well at both room temperature and low temperature. If the curing temperature is around 25℃, it can withstand the design load in 2 days; if the curing temperature is around 5℃, it can withstand the load in 4 days, and the anchoring force continues to increase over time.

[0021] a7. Inspection and acceptance: Randomly sample and inspect 3-4 days after rebar installation. Perform a pull-out test on the system consisting of jacks, anchors, and reaction frames.

[0022] A3. Pouring hinge joint concrete and paving concrete; After the anchoring adhesive has cured, the hinge joint is rinsed and moistened with a high-pressure water gun. Foam board is used to seal the bottom of the hinge joint, and cement mortar with the same mix ratio as the hinge joint concrete is laid. The shear bars and longitudinal reinforcing bars are placed inside the hinge joint, and C50 micro-expansion cellulose fiber concrete is poured, with a cellulose fiber content of 1.2 kg / m³. 3 The impermeability grade is P6; the concrete is compacted using an immersion vibrator, and after the concrete has set, it is immediately covered with non-woven geotextile and watered for curing.

[0023] S3. Beam and slab replacement; If a beam or slab in a bridge structure is severely damaged, has insufficient load-bearing capacity, or is outdated in technical standards, the old beam or slab should be removed and a new beam or slab installed. The replaced beam or slab should be visually inspected and its quality accepted to ensure that it meets the design requirements and relevant specifications and standards.

[0024] S4. Bridge jacking and bearing replacement: Erect a hydraulic synchronous jacking system, including a jacking system, a monitoring system and a temporary support system, and achieve multi-point synchronous jacking of the beam body through PLC computer control. After the beam is lifted into position, temporary supports are placed on the beam. The original bearing pads are removed, wedge blocks are constructed on the bottom of the beam within the bearing area, and the bearing pads are recast to ensure that the top surface of the new bearing pads and the wedge blocks on the bottom of the beam are in a horizontal state. The new bearings are then installed to complete the bridge lifting construction.

[0025] The jacking process includes construction preparation, commissioning and installation of the jacking system, installation of the monitoring system, pre-jacking, formal jacking, construction of new support pads and beam bottom wedges, support replacement, beam lowering, dismantling of jacking equipment, and site cleanup. B1. Construction preparation; Temporary steel brackets are installed on the side of the cap beam 5 below the outer support of the bridge pier side beam at the discontinuous section to facilitate the placement of jacks 7 and temporary supports 8. The upper and lower base surfaces of the remaining pier cap beam 5 or cap jacks 7 and temporary supports 8 are cleaned, the protruding parts of the base surface are chiseled off, and the broken and loose concrete debris is removed to make the base surface level. Before jacking, the expansion joints of the entire bridge must be removed to ensure that the replacement of the bearings does not affect the structure of the adjacent spans. The old bridge deck asphalt concrete must be milled first, and the outer guardrails must be cut with a water jet. The erected jacking support must be inspected to ensure that it has sufficient strength, rigidity and stability. The mid-span deflection of the support must be less than 10mm to ensure that the support does not collapse or tilt when the beam is jacked up, and that the settlement is small and uniform. Before jacking, the anti-lateral displacement device and the limiting device should be carefully checked. Before jacking up, it is necessary to check whether seismic anchor bolts are installed at the pier. If so, the restraints must be released before jacking up. After jacking up, the original seismic anchor bolts should be welded. B2. Commissioning and installation of the lifting system; The jacking system uses dual control of displacement and jacking pressure as the basis for jacking control. External data acquisition uses electronic displacement sensors for displacement acquisition and pressure sensors for pressure acquisition. Before that, the normal operation of each control system should be tested individually and uniformly. B3. Installation of the monitoring system; The monitoring system is an auxiliary device for the jacking system, mainly consisting of pressure sensors, displacement sensors, dial gauges, etc. The displacement sensors are installed near the support jack 7 to control the displacement during the jacking process. The pressure sensors should be installed in conjunction with the jacks to accurately reflect the pressure values ​​borne by the jacks. At the same time, dial gauges should be installed on the bottom plate of the beam as auxiliary displacement control and correction measures. B4. Pre-lifting (based on lifting beam 1 by 2mm); The main purpose of pre-lifting is to eliminate potential problems in the lifting system, such as oil leaks at the oil line joints or insufficient oil pump pressure, while also eliminating inelastic deformation that may occur during the lifting process. The pre-lifting is controlled by jack 7 to the design load. It is necessary to ensure that beam 1 is lifted synchronously during the lifting and the load is held for more than 5 minutes before unloading. After unloading, the control systems and appearance of the system should be carefully checked. The key points of the inspection include: whether there is any oil leakage in all oil circuits, whether there is any abnormality in jack 7, and the appearance of wear on the power supply line. After unloading, carefully check whether the upper and lower steel plates of jack 7 are deformed. If necessary, the thickness of the steel plates can be adjusted to meet the lifting requirements. Carefully check the structure under the jack 7 position to see if there are any differences from before the lifting. If there are any, the cause should be carefully found out before the lifting can be carried out. It is strictly forbidden to continue lifting when the situation is unclear. B5. Formal jacking up; The process is to be completed in multiple stages. After each stage is lifted into place, the temporary support 8 should be adjusted in a timely manner to ensure that its top surface is in close contact with the bottom of the beam. Lifting steps: b1, First lifting; b2, Installation of temporary support 8; b3, Second lifting; b4, Adjustment of the height of temporary support 8; b5, Third lifting; b6, Adjustment of the height of temporary support 8; b7, Lowering the beam onto temporary support 8; B6. Construction of new support pad stones and beam bottom wedge blocks; After confirming on-site that the jacking height meets the design requirements, remove the old bearing, chisel away the original bearing pad, and then pour new bearing pads with C50 concrete (using D8 steel mesh inside the pads) to ensure that the top surface of the bearing pad and the bottom surface of the wedge block remain level. The original embedded steel plate on the upper part of the bearing should be ground and rust-removed until it has a metallic luster. After roughening the surrounding local concrete (within the area of ​​the newly added leveling galvanized steel plate), use structural adhesive to attach the leveling galvanized steel plate, and then install the new bearing (note that the PTFE sliding plate of the PTFE sliding plate bearing should face upwards). Considering durability and practical performance, the structural adhesive is leveled using an extrusion method based on practical experience. The adhesive thickness is thicker in the center of the steel plate and thinner at the edges, with the thickness controlled at approximately 5mm in the center and approximately 3mm at the edges. When the embedded steel plate is not level with the concrete at the bottom of the beam, appropriate treatment should be carried out after the original support is removed from the beam. The unevenness between the embedded steel plate and the concrete at the bottom of the beam can easily cause the support to be damaged by biting. The protruding concrete needs to be chiseled away to ensure that it is level with the embedded steel plate. B7. Replacement of bearing; During installation, prevent the support from being subjected to eccentric pressure or excessive initial shear deformation. After installation, ensure that the support is in close contact with the upper and lower structures and that there is no gap. After the supports are installed, conduct a comprehensive inspection to check whether any supports are missing, whether the support installation direction and type are correct, and whether the PTFE sliding plate supports have been injected with silicone grease. It is strictly forbidden to use lubricating oil instead of silicone grease. Ensure the normal operation of the supports after installation, and record any deviations and abnormalities that occur after the supports are installed. B8. Lowering the beam; The beam lowering procedure is the opposite of the jacking procedure and should be strictly followed. Before lowering the beam, it should be confirmed that all temporary supports have been removed and steel pads have been installed. After the beam is lowered to the support point and bears the load, attention should be paid to the data shown by the displacement and pressure sensors, whether the deceleration of each pier is consistent, and whether the displacement changes are consistent. If the difference is too large, the cause should be found and dealt with before lowering the beam again. B9. Dismantle the lifting equipment and clean up the site.

[0026] S5. Final acceptance; Load-bearing capacity testing verifies whether the reinforced bridge meets design requirements through static or dynamic load tests.

[0027] As needed, a long-term bridge monitoring system can also be established to regularly check the durability of reinforcement materials and the structural adaptability.

[0028] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

Claims

1. A method for repairing and reinforcing an old bridge, characterized in that, The specific steps include: S1. Install a protection system to monitor the structural status in real time during construction, and immediately stop work and make adjustments if any hidden dangers are found. S2. Joint repair, including joint removal, rebar installation, pouring joint concrete, and paving concrete. The construction sequence for rebar installation is as follows: positioning, drilling, hole cleaning, steel rust removal, rebar adhesive preparation, rebar installation, curing, protection, inspection and acceptance. S3. Beam and slab replacement: visual inspection and quality acceptance of the replaced beams and slabs. S4. Bridge jacking and bearing replacement: Erect a hydraulic synchronous jacking system, including a jacking system, a monitoring system and a temporary support system, and control it with a PLC computer to achieve multi-point synchronous jacking of the beam (1). The jacking process includes construction preparation, commissioning and installation of the jacking system, installation of the monitoring system, pre-jacking, formal jacking, construction of new support pads and beam bottom wedges, support replacement, beam lowering, dismantling of jacking equipment, and site cleanup. S5. Final acceptance and load-bearing capacity testing: Verify whether the reinforced bridge meets the design requirements through static or dynamic load tests.

2. The method for repairing and reinforcing an old bridge according to claim 1, characterized in that, In step S1, the protection system includes a safety protection platform and a beam posture safety monitoring facility. The safety protection platform includes a lifting work platform (4) and a limiting steel truss (3). The lifting work platform (4) includes an operating platform (41), a scissor lift (42), and a movable base (43). The limiting steel truss (3) is set on both sides of the bridge. The limiting steel truss (3) is fixedly connected to the ground through a pre-embedded base (31). One end of the operating platform (41) is provided with a sliding seat (44). The limiting steel truss (3) is provided with a slide rail corresponding to the sliding seat (44). The beam posture safety monitoring facility includes displacement sensors, tilt sensors, and environmental monitoring sensors. The displacement sensors include laser rangefinders, total stations, GPS devices, and wire displacement gauges. The tilt sensors include electronic levels, inclinometers, and gyroscopes. The environmental monitoring sensors include ambient temperature sensors, wind speed sensors, and vibration sensors.

3. The method for repairing and reinforcing an old bridge according to claim 1, characterized in that, In step S2, the rebar installation steps include: a1. Positioning: Mark the drilling location and model according to design requirements; a2. Drilling: Use an electric hammer or pneumatic drill to drill holes. If you encounter reinforcing bars, adjust the hole position to avoid them. Wash the debris inside the hole with clean water and dry it. The hole diameter is d+4~8mm. The hole depth should not be set inside the protective layer or decorative layer of the component. a3. Clean the hole. After drilling, check that the hole depth and diameter are within acceptable limits. Blow out the dust inside the hole with compressed air, then clean the hole wall with a brush and cotton cloth. Blow the hole again with compressed air, repeating this process 3 to 5 times until there is no dust or debris inside the hole. Finally, wipe the hole wall clean with a cotton cloth soaked in acetone and temporarily seal the hole opening. If there are any unusable holes, fill them with anchoring adhesive after cleaning. Keep the drilled hole dry. a4. Remove rust from steel materials, thoroughly cleaning away rust and oil stains within the anchoring length of the steel materials; a5. Rebar installation: Prepare the rebar installation adhesive according to the ratio, stir it evenly, and inject it into the hole using an injection gun. The amount of rebar installation adhesive should generally be 2 / 3 of the hole depth, and a small amount of adhesive should overflow around the rebar after it is inserted. Immediately after injecting the anchoring adhesive, rotate the inserting rebar in one direction until the designed depth is reached, ensuring that the gap between the inserted rebar and the hole wall is uniform, and correcting the position and verticality of the rebar. a6. Curing and protection: The reinforcing bars must not be disturbed during the curing process of the adhesive. If there is significant disturbance, the reinforcing bars must be re-installed. a7. Inspection and acceptance: Randomly sample and inspect 3-4 days after rebar installation. Perform a pull-out test on the system consisting of jacks, anchors, and reaction frames.

4. The method for repairing and reinforcing an old bridge according to claim 1, characterized in that, In step S2, the following steps are taken: pouring and laying the joint concrete: after the anchoring adhesive has cured, the joint is rinsed and moistened with a high-pressure water gun, the bottom of the joint is sealed with foam board, and cement mortar with the same mix ratio as the joint concrete is laid. The shear bars and longitudinal reinforcing bars are placed in the joint, fiber concrete is poured, and a vibrator is inserted to compact it. After the concrete has set, it is immediately covered with non-woven geotextile and watered for curing.

5. The method for repairing and reinforcing an old bridge according to claim 1, characterized in that, In step S4, the bridge jacking and bearing replacement steps are as follows: B1. Construction preparation; B2. Commissioning and installation of the lifting system; B3. Installation of the monitoring system; B4. Pre-lifting; B5. Formal jacking is completed in multiple stages. After each stage of jacking is completed, the temporary support (8) should be adjusted in time to ensure that its top surface is in close contact with the bottom of the beam. B6. Construction of new support pad stones and beam bottom wedge blocks; B7. Replacement of bearing; B8. Lowering the beam; The beam lowering procedure is the opposite of the jacking procedure. Before lowering the beam, confirm that all temporary supports (8) have been removed and the steel pads have been installed. After the beam is lowered to the support point, pay attention to the data shown by the displacement and pressure sensors to ensure that the deceleration and displacement changes of each pier are consistent. If the difference is too large, find out the cause and deal with it before lowering the beam again. B9. Dismantle the lifting equipment and clean up the site.

6. The method for repairing and reinforcing an old bridge according to claim 5, characterized in that, In step B1, construction preparation: temporary steel brackets are installed on the side of the cap beam (5) below the outer support of the bridge pier side beam at the discontinuous section. The upper and lower base surfaces of the remaining pier cap beam (5) or cap jack (7) and temporary support (8) are cleaned, the protruding parts of the base surface are removed, and the broken and loose concrete slag is removed so that the base surface is in a horizontal state. Before jacking, the expansion joints of the entire bridge must be removed to ensure that the replacement of the bearings does not affect the structure of the adjacent spans. The old bridge deck asphalt concrete must be milled first, and the outer guardrails must be cut with a water jet. The erected jacking support must be inspected to ensure that it has sufficient strength, rigidity and stability. The mid-span deflection of the support must be less than 10mm to ensure that the support does not collapse or tilt when the beam is jacked up, and that the settlement is small and uniform. Before jacking, the anti-lateral displacement device and the limiting device should be carefully checked. In step B2, the commissioning and installation of the jacking system: the jacking system adopts dual control of displacement and jacking pressure as the basis for jacking control. External data acquisition uses electronic displacement sensors for displacement acquisition and pressure sensors for pressure acquisition. Before that, the normal operation of each control system should be individually and uniformly debugged. In step B3, the monitoring system is installed: the monitoring system is a supporting device for the jacking system, including pressure sensors, displacement sensors, and dial gauges; The displacement sensor is installed near the support jack (7) to control the closest distance and accurately reflect the displacement during the jacking process; the pressure sensor is installed in a matching manner to accurately reflect the pressure value borne by the jack (7); at the same time, a dial gauge should be installed on the bottom plate of the beam as an auxiliary displacement control and correction control measure.

7. The method for repairing and reinforcing an old bridge according to claim 6, characterized in that, In step B4, the main purpose of pre-lifting is to eliminate potential problems in the lifting system, such as oil leakage at the oil line joints or insufficient oil pump pressure, while also eliminating potential inelastic deformation during the lifting process. The pre-lifting is controlled by jacks (7) to the design load. It is necessary to ensure that the beam (1) is lifted synchronously during the lifting and the load is held for more than 5 minutes before unloading. After unloading, the system’s control systems and appearance should be carefully checked. The key points of the check include: whether there is any oil leakage in all oil circuits, whether there is any abnormality in the jack (7), and the appearance of wear on the power supply line. After unloading, carefully check whether the upper and lower steel plates of the jack (7) are deformed. If necessary, the thickness of the steel plates can be adjusted to meet the lifting requirements. Carefully check the structure under the jack (7) to see if there are any differences from before the lifting. If there are, the cause should be carefully found out before the lifting can be carried out. It is strictly forbidden to continue lifting when the situation is unclear.

8. The method for repairing and reinforcing an old bridge according to claim 7, characterized in that, In step B6, after confirming on-site that the jacking height has reached the design requirements, the old support is removed, the original support pad is chiseled away, and a new support pad is poured to ensure that the top surface of the support pad and the bottom surface of the wedge block remain horizontal; the original embedded steel plate on the upper part of the support should be ground and rust removed until it has a metallic luster, and the surrounding local concrete should be roughened. Then, the galvanized steel plate should be leveled by using structural adhesive, and then the new support should be installed. When the embedded steel plate is not level with the concrete at the bottom of the beam, appropriate treatment should be carried out after the original support is removed from the beam. Unevenness between the embedded steel plate and the concrete at the bottom of the beam can easily lead to damage to the support edge. The protruding concrete needs to be chiseled away to ensure that it is flush with the embedded steel plate.

9. A method for repairing and reinforcing an old bridge according to claim 8, characterized in that, In step B7, during the installation of the support, it is necessary to prevent the support from being biased or generating excessive initial shear deformation. After the installation is completed, it must be ensured that the support is in close contact with the upper and lower structures, and there must be no gaps. After the supports are installed, conduct a comprehensive inspection to check whether any supports are missing, whether the support installation direction and type are correct, to ensure the normal operation of the supports after installation, and record any deviations and abnormalities that occur after the supports are installed.

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