Man-machine composite regulation and control method for high-precision hydraulic synchronous lifting of bridge precast beam slab

Abstract

The invention relates to a man-machine composite regulation and control method for high-precision hydraulic synchronous lifting of a bridge precast beam slab, which comprises the following steps of: integrating beforehand error elimination and process error suppression through a multi-layer synchronization control system to realize synchronization guarantee; the multi-level synchronism control system comprises an initial posture collaboration layer, a hydraulic system foundation synchronization layer, a mechanical stroke limiting layer and a manual fine adjustment compensation layer, and high-precision and high-synchronism control of a bridge precast beam plate in the hydraulic lifting process is achieved by combining a mechanical device and manual operation. The method has the remarkable beneficial effects in the aspects of synchronous control precision, cost effectiveness, adaptability, construction efficiency, construction safety, popularization and application and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge prefabrication and installation construction, and specifically relates to a human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beams and slabs. Background Technique

[0002] The hydraulic lifting technology for precast bridge beams and slabs is an efficient method suitable for bridge installation in complex and restricted environments. This technology uses hydraulic devices to lift the precast beams and slabs to the predetermined positions, achieving rapid and safe bridge installation. During the hydraulic lifting process of precast bridge beams and slabs, the selection of the lifting method is crucial for synchronous control and the quality and safety of the entire installation process.

[0003] The existing hydraulic lifting methods for precast bridge beams and slabs generally include steps such as the preparation stage, support installation and positioning, hydraulic device installation and commissioning, beam and slab connection and trial lifting, formal lifting, and beam lowering and positioning. In the preparation stage, construction preparation work such as site cleaning and material preparation needs to be carried out; subsequently, according to the size, weight, and lifting requirements of the beams and slabs, the lifting and lowering beams supports are installed and positioned to ensure the stability and safety of the beams and slabs during the lifting process; then, hydraulic devices such as hydraulic pump stations, oil pipes, and jacks are connected and commissioned to the normal working state; afterwards, the beams and slabs are firmly connected to the lifting equipment such as balance beams using shackles or other connectors, and trial lifting is carried out to check the connection reliability of each component and the synchronism of the hydraulic system; after ensuring that everything is ready, formal lifting begins. During the process, the attitude and elevation changes of the beams and slabs need to be closely monitored, and the parameters of the hydraulic system are adjusted in a timely manner to maintain synchronism; finally, when the beams and slabs are lifted to the predetermined positions, smooth beam lowering is achieved by controlling the parameters of the hydraulic system, and it is ensured that the beams and slabs can be accurately positioned.

[0004] However, in the existing hydraulic lifting process of precast girders and slabs for bridges, synchronous control has always been a technical problem to be solved. Currently, there are mainly two methods for synchronous control technology: one is to rely on pressure sensors, displacement sensors, and PLC control systems to achieve synchronous control. Although this method can achieve high synchronous accuracy, its equipment cost is high, and the installation, debugging, and maintenance processes are complex, especially in complex and restricted space environments, and it is even more difficult. Moreover, once a failure occurs, repair and replacement are extremely inconvenient. In addition, due to the accuracy and stability limitations of the sensors and control systems themselves, as well as the interference of environmental factors (such as temperature, humidity, etc.), the synchronous control accuracy may decrease. The other is to use conventional mechanical synchronous devices. Although this method has relatively low cost, it is prone to cumulative errors in long-stroke operations. These cumulative errors mainly come from factors such as wear, deformation of mechanical components, and loosening of connection parts. As the lifting stroke increases, these errors will gradually accumulate, eventually leading to the inclination of the beam body, affecting the installation quality and safety of the bridge. Especially in large bridge projects, the weight and size of the girders and slabs are relatively large, and the requirements for synchronous control accuracy are also higher. Therefore, conventional mechanical synchronous devices are difficult to meet their needs. Summary of the Invention

[0005] The present invention aims to overcome the defects of the prior art and provide a human-machine composite control method for high-precision hydraulic synchronous lifting of precast girders and slabs for bridges, so as to solve the problem of synchronous control in the lifting operation.

[0006] In order to solve the above technical problems, the present invention is implemented as follows: A human-machine composite control method for high-precision hydraulic synchronous lifting of precast girders and slabs for bridges, characterized in that: this method realizes synchronous guarantee through a multi-level synchronous control system, comprehensively eliminating errors in advance and suppressing errors during the process; the multi-level synchronous control system includes an initial attitude coordination layer, a basic synchronization layer of the hydraulic system, a mechanical stroke limit layer, and an artificial fine-tuning compensation layer, and combines mechanical devices and manual operations to achieve high-precision and high-synchronous control of precast girders and slabs for bridges during the hydraulic lifting process.

[0007] The described human-machine composite control method for high-precision hydraulic synchronous lifting of precast girders and slabs for bridges is characterized in that: the initial attitude coordination layer is specifically: Measure the actual straight-line distance and the current longitudinal slope of the beam slab suspension points; based on the actual and design data of the beam length, suspension point position, and longitudinal slope, calculate and determine the placement position of the lifting and lowering beam supports to adjust the initial attitude of the beam slab to the design requirements and eliminate the synchronous deviation caused by the longitudinal slope of the beam slab. Among them, the offset calculation formula for calculating and determining the placement position of the lifting and lowering beam supports is: Offset △L = (L1 - L2) / 2 = L×[cos(a1) - cos(a2)] / 2; △L: Represents the offset; L: Represents the straight-line distance between the lifting points at both ends of the beam-slab; L1: Represents the horizontal distance between the lifting points at both ends of the beam-slab under the longitudinal slope of the beam-slab before lifting; L2: Represents the horizontal distance between the lifting points at both ends of the beam-slab after adjusting the initial attitude; a1: Represents the horizontal angle corresponding to the longitudinal slope of the beam-slab before lifting; a2: Represents the horizontal angle corresponding to the longitudinal slope of the beam-slab after being in place, that is, the horizontal angle after adjusting the initial attitude.

[0008] The described human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beam-slab is characterized in that: The basic synchronous layer of the hydraulic system is specifically: using hydraulic devices such as hydraulic pump stations, oil pipes, and jacks with unified specifications; adopting a double-pump and four-cylinder shunt system, where a single oil pump synchronously drives two jacks on the same side, and an equal distribution of oil volume is achieved through a three-way shunt with a flow-regulating handle to improve the synchronism of the hydraulic system.

[0009] The described human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beam-slab is characterized in that: The mechanical stroke limit layer is specifically: evenly splitting the total height difference of lifting and lowering the beam into several equal stroke segments within the effective stroke of the jack, excluding the last lowering stroke; setting stroke limit plates to ensure that the actual strokes of each point during four-point lifting are the same within each stroke segment, so as to reduce cumulative errors and ensure synchronism.

[0010] The described human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beam-slab is characterized in that: After completing the initial attitude adjustment and before the formal lifting and lowering of the beam, it is necessary to determine the number of cyclic lowering times and the last lowering stroke according to the measured total height difference of lowering the beam and the stroke value set by the stroke limit plate; Total height difference of lowering the beam = current actual elevation - designed elevation.

[0011] Single-time lowering height difference in the cyclic lowering section = limit stroke; Last lowering height difference = total height difference of lowering the beam - (single-time lowering height difference × number of cycles); the number of cycles is a positive integer; Considering the deformation of the lifting and lowering support of the beam, the jack needs to preset a 10mm stroke. The single-time lowering stroke of the jack in the cyclic lowering section = single-time lowering height difference + 10mm, that is, the maximum stroke of the jack; Jack's last lowering stroke = last lowering height difference + 10mm.

[0012] The described human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beams and slabs is characterized in that: the specific artificial fine-tuning compensation layer is as follows: during the lifting process, the synchronism of the four points of the beam and slab is observed manually; when the synchronism deviation is large, immediate artificial fine-tuning measures are taken, such as adjusting the oil pressure or stroke of the jack, to ensure that the beam and slab can be lifted smoothly and synchronously to the designed elevation position.

[0013] The described human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beams and slabs is characterized in that this method further includes the following operation processes: Step 1: Conduct site cleaning and material preparation; Step 2: Measure and place the lifting and lowering beam supports, and the placement position of the lifting and lowering beam supports is determined according to the offset calculation formula; Step 3: Install the entire set of lifting equipment such as hydraulic lifting devices and balance beams, and conduct commissioning and inspection; Step 4: Connect the beam and slab to the balance beam, conduct a trial lift and adjust the initial attitude; Step 5: Determine the stroke segmentation and the height difference of the last beam lowering; Step 6: Synchronously operate the hydraulic device and gradually lift it to the designed elevation position according to the preset stroke segments; Step 7: During the lifting process, continuously conduct manual observation and fine-tuning compensation to ensure synchronism; Step 8: After the lifting is completed, conduct necessary adjustments and finishing work, such as adjusting the height of the temporary support and removing the hydraulic lifting device.

[0014] The beneficial effects of the present invention are as follows: It can be seen from the above technical solutions that the present application provides a human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beams and slabs. Through means such as specific hydraulic circuit design, combined with mechanical limit devices and artificial fine-tuning compensation, the synchronous control accuracy of ±3 mm level is achieved without relying on high-precision sensors and complex control systems. At the same time, this method also has the advantages of low cost, simple operation, and convenient maintenance, and is particularly suitable for the hydraulic lifting operation of precast bridge beams and slabs in complex and restricted environments.

[0015] Compared with the traditional synchronous control method that relies on high-precision sensors and complex control systems, the present invention only needs to rely on small-scale conventional hydraulic devices, fittings, and simple mechanical limit devices, greatly reducing the equipment cost. At the same time, due to the simple operation and convenient maintenance, the operation and maintenance costs during the construction process are also reduced, improving the economic benefits of the project.

[0016] The mechanical-artificial composite control method proposed by the present invention does not rely on a complex electronic control system, so it has stronger adaptability in complex and restricted space environments. Whether it is the construction of urban viaducts, mountain bridges or bridges in other special environments, it can be flexibly applied to meet the needs of different construction scenarios.

[0017] Through precise calculations and reasonable operation process design, the present invention effectively shortens the time cycle of the hydraulic lifting operation of precast beam slabs of bridges. It reduces rework and delays caused by synchronous control problems and improves the efficiency of the entire bridge construction process.

[0018] The present invention strictly controls the key points of synchronous control, avoiding safety accidents such as beam body tilt and falling caused by poor synchronism. At the same time, through the design of the manual fine-tuning compensation layer, it ensures the safety and stability during the construction process, has strong replicability and popularizability, and is expected to be widely applied in the hydraulic lifting operation of precast beam slabs of bridges, promoting the progress and development of bridge construction technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following further describes the present invention in detail with reference to the drawings and embodiments: Figure 1 It is a framework diagram of a multi-level synchronous control system; Figure 2 It is a schematic diagram of a double-pump four-cylinder shunt hydraulic system; Figure 3 It is a schematic diagram of the offset of the placement position of the lifting and lowering beam supports; Figure 4 It is a schematic diagram of the mechanism composition of the single-sided lifting and lowering beam supports and the lifting system at large and small mileage; Figure 5 It is a schematic diagram of the operation of a single lifting and lowering beam stroke segment; Figure 6 It is a schematic diagram of the setting of the stroke limit plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope claimed by the present application. Embodiment 1 As Figure 1Shown: A human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beams and slabs. This method realizes synchronous guarantee through a multi-level synchronization control system, comprehensively eliminating errors in advance and suppressing errors during the process. The multi-level synchronization control system includes an initial attitude coordination layer, a basic synchronization layer of the hydraulic system, a mechanical stroke limit layer, and an artificial fine-tuning compensation layer. Combining mechanical devices and manual operations, it realizes high-precision and high-synchronization control of precast bridge beams and slabs during hydraulic lifting, without relying on a complex and costly electronic sensor system. This method was developed for the construction project of precast bridge beams and slabs, but its applicable scenarios are not limited to this.

[0021] Initial attitude coordination layer: For pre-control, based on actual and design data such as beam length, lifting point position, and longitudinal slope, calculate and determine the placement of the lifting and lowering beam supports and adjust the initial attitude of the beam slab.

[0022] Basic synchronization layer of the hydraulic system: For pre-control, the main measures include: ① restricting the unification of the specifications of hydraulic devices such as hydraulic pump stations, oil pipes, and jacks used for lifting; ② a double-pump four-cylinder shunt system, where a single oil pump synchronously drives 2 jacks on the same side, as Figure 2 shown; ③ selecting a three-way shunt with a flow adjustment handle to achieve balanced oil distribution.

[0023] Mechanical stroke limit layer: For process control, including: ① stroke segmented control, evenly splitting the total height difference of lifting and lowering the beam into several equal stroke segments within the effective stroke of the jack, excluding the last lowering stroke; ② setting stroke limit plates to ensure that the actual strokes of each point in each stroke segment are the same during four-point lifting.

[0024] Artificial fine-tuning compensation layer: For process control, that is, manually observing the four-point synchronization during the process of lifting and lowering the beam and correcting deviations in a timely manner. Methods such as using a theodolite to measure the relative elevation of the four points of the beam slab and using a feeler gauge to measure the change in the gap between the balance beam and the lower cushion plate can be used.

[0025] The hydraulic lifting operation steps based on this method are as follows: Step 1: Construction preparation work such as site cleaning and material preparation.

[0026] Step 2: Measure and determine the placement position of the lifting and lowering beam supports and complete the placement.

[0027] The specific operations in this link are as follows; Operation 2.1: Use corresponding measuring tools to measure the actual straight-line distance between the lifting points of the beam slab and the current longitudinal slope, etc.

[0028] Operation 2.2: Taking the center point of the beam slab as the rotation point, compare the horizontal distance between the lifting points of the beam slab under the current longitudinal slope and the required longitudinal slope for installation, and determine the offset △L of the placement position of the lifting and lowering beam supports, as Figure 3 shown.

[0029] Before the formal lifting and lowering of the beam, the initial attitude of the beam slab must be adjusted according to the designed longitudinal and transverse gradients to avoid disturbing the initially set synchronous operation due to attitude correction during the lifting and lowering process; the placement position of the lifting and lowering beam support should be offset adjusted according to the placement position obtained from the analysis of the initial attitude adjustment. Its calculation formula is: offset △L = (L1 - L2) / 2 = L×[cos(a1) - cos(a2)] / 2.

[0030] Where: △L: represents the offset; L: represents the straight-line distance between the lifting points at both ends of the beam slab; L1: represents the horizontal distance between the lifting points at both ends of the beam slab under the longitudinal gradient of the beam slab before lifting; L2: represents the horizontal distance between the lifting points at both ends of the beam slab after adjusting the initial attitude; a1: represents the horizontal angle corresponding to the longitudinal gradient of the beam slab before lifting; a2: represents the horizontal angle corresponding to the longitudinal gradient of the beam slab after being in place, that is, the horizontal angle after adjusting the initial attitude.

[0031] Operation 2.3: Place the assembled lifting and lowering beam support at the specified position. The lifting and lowering beam supports at both the large and small mileage ends should be perpendicular to the beam slab, and the midline should be aligned with the longitudinal midline of the beam slab. Adjust the level by adding shims such as cushion plates to make the crossbeam of the lifting and lowering beam support horizontal.

[0032] After completing the placement of the lifting and lowering beam support according to the above operations, before the hydraulic lifting operation, the position deviation of the lifting and lowering beam support caused by the longitudinal slope of the beam slab can be eliminated, avoiding disturbing the established synchronous setting due to adjusting the installation longitudinal slope during the hydraulic lifting operation; at the same time, it also enables the fine-threaded steel rod to maintain a better stress state during the lifting and lowering of the beam, reducing bending and ensuring safety.

[0033] Step 3: Install the entire set of lifting equipment such as the hydraulic lifting device and the balance beam, and debug and inspect.

[0034] The specific operations of this link are as follows; Operation 3.1: After the lifting and lowering beam support is placed in place, find the position of the lifting point of the beam slab, and use a marker pen to mark the alignment center line on the crossbeam of the lifting and lowering beam support.

[0035] Operation 3.2: Referring to the alignment center line, place steel cushion plates with central holes on the top surface and the inner bottom surface of the crossbeam of the lifting and lowering beam support respectively.

[0036] Operation 3.3: Based on the position of the lifting point, place the balance beam, and pad and level it with sleepers. It is required that the balance beam and the lifting and lowering beam support are in the same vertical plane, and the lifting point holes of the balance beam are aligned with the lifting points of the beam slab.

[0037] Operation 3.4: Place a jack on the top backing plate of the crossbeam just placed, place a positioning nut on the inner bottom surface backing plate of the crossbeam, and place another steel backing plate with a central hole on the top of the jack.

[0038] Operation 3.5: Thread two nuts onto the precision rolling threaded rod and screw them to the same side near the end.

[0039] Operation 3.6: Bind one end of the precision rolling threaded rod through which the nut is threaded with a sling, vertically lift and install it, so that the precision rolling threaded rod passes through the steel backing plate on the top of the jack, the jack, the steel backing plate on the top of the crossbeam, the crossbeam, the positioning nut inside the crossbeam, the steel backing plate on the inner bottom surface of the crossbeam, and the balance beam in sequence.

[0040] Operation 3.7: Select one side of the large and small mileage sides, start connecting the hydraulic circuit, and connect the main oil inlet pipe to the oil inlet of the oil inlet tee with a regulating valve.

[0041] Operation 3.8: Connect the oil inlet branch pipe to the oil outlet of the oil inlet tee with a regulating valve, and connect the other end of the oil inlet branch pipe to the oil inlet of the jack.

[0042] Operation 3.9: Connect the oil return branch pipe to the oil outlet of the jack, and connect the other end of the oil return branch pipe to the oil inlet of the oil return tee.

[0043] Operation 3.10: Repeat Operations 3.8 - 3.9 to complete the connection of the other oil inlet branch pipe, oil return branch pipe on this side and another jack.

[0044] Operation 3.11: Connect the main oil return pipe to the oil outlet of the oil return tee.

[0045] Operation 3.12: Connect the other ends of the main oil inlet pipe and the main oil return pipe to the oil outlet and oil return port of the hydraulic pump truck respectively.

[0046] Operation 3.13: Repeat Operations 3.7 - 3.13 to complete the connection of the hydraulic circuit on the other side of the large and small mileage sides.

[0047] Operation 3.14: Adjust the regulating valves of the oil inlet tees on the hydraulic circuits of the large and small mileage sides to control the equal distribution of the flow rate.

[0048] Operation 3.15: After checking that the hydraulic circuit connection is not loose, start the hydraulic pump truck, slowly boost the pressure according to the test pressure, and observe the telescopic synchronization of the jack cylinder and the tightness of the hydraulic circuit.

[0049] Operations 3.1 - 3.6 in this step are for the installation of the lifting component, and steps 3.7 - 3.13 are to complete the connection and commissioning of the hydraulic device. The structural composition of the lifting and lowering beam support on one side of the large and small mileage and the mechanism of the lifting system are as Figure 4As shown. Before the formal implementation, tests should be carried out to determine the target oil pressure for the hydraulic pump truck to boost the pressure.

[0050] Step 4: Shackle-connect the beam slab and the balance beam, and test lift and adjust the initial attitude.

[0051] The specific operations in this link are as follows; Operation 4.1: For the precision rolling threaded rod passing through the balance beam, successively install the perforated steel backing plate and nuts from the bottom.

[0052] Operation 4.2: Manually adjust the 4 positioning nuts inside the cross beam of the reset lifting and lowering beam support so that their bottom surfaces are close to the inner backing plate of the cross beam.

[0053] Operation 4.3: Manually adjust the backing plate and nuts at the bottom of the balance beam so that the backing plate and nuts are close to the bottom surface of the balance beam.

[0054] Operation 4.4: Select shackles of the same specification and with dimensions and bearing capacity meeting the connection requirements to connect the beam slab and the balance beam.

[0055] Operation 4.5: Manually adjust the backing plate and nuts at the top of the precision rolling threaded rod so that the backing plate and nuts are close to the top surface of the jack under the fully retracted state of the oil cylinder.

[0056] Operation 4.6: Synchronously operate the hydraulic lifting devices at both large and small mileage to test lift until the jack oil cylinders all extend to about 1 / 2 of the stroke, and maintain for no less than 5 minutes to observe changes in oil pressure, stroke, elevation, etc.

[0057] After the test lift is normal, according to the current longitudinal slope of the beam slab and the required longitudinal slope for installation, separately operate the hydraulic lifting device on the side that needs to be lifted at both large and small mileage to adjust the longitudinal slope of the beam slab to the required longitudinal slope for installation and complete the initial attitude adjustment; during this operation process, if the positioning nuts are restricted by the stroke limit plate, the position of the positioning nuts can be screwed multiple times as needed until the initial attitude adjustment is completed.

[0058] Operation 4.8: After completing the initial attitude adjustment of the beam slab, keep the jack still, and respectively restore the 4 positioning nuts inside the cross beam of the lifting and lowering beam support so that the bottom surfaces of the positioning nuts are close to the inner backing plate of the cross beam.

[0059] Operation 4.9: Remove the original support frame of the beam slab and prepare for the formal hydraulic lifting and lowering of the beam.

[0060] The purpose of Operations 4.1 - 4.5 in this step is to ensure that all components are tightly connected before adjusting the initial attitude, reduce the lateral torsion of the beam body caused by differences in connection gaps, and ensure the correct initial positions of the nuts at different parts, reducing the position adjustment of the nuts at each part during the initial attitude adjustment.

[0061] Step 5: Determine the stroke segmentation and the elevation difference at the last beam lowering.

[0062] The specific operations of this step are as follows; Operation 5.1: After removing the original support frame of the beam-slab, synchronously operate the hydraulic lifting devices at both the large and small mileage ends to fully retract the jack cylinders at the 4 positions.

[0063] Operation 5.2: Manually adjust the backing plates and nuts at the tops of the 4 fine-rolled threaded rods so that the backing plates, nuts, and the top surfaces of the jacks are in close contact.

[0064] Operation 5.3: Set the stroke height limited by the stroke limit plate: Limited stroke = Maximum stroke of the jack - 10 mm, that is, the distance between the bottom surface of the stroke limit plate and the top surface of the internal positioning nut of the lifting and lowering beam support crossbeam; This operation should preferably be carried out during the processing and manufacturing of the lifting and lowering beam support crossbeam.

[0065] Operation 5.4: Synchronously control the hydraulic devices at both the large and small mileage ends to make the stroke of the jack cylinders at the 4 positions between 10 mm and the limited stroke, and maintain and pause the lifting.

[0066] Operation 5.5: Manually adjust the 4 internal positioning nuts of the lifting and lowering beam support crossbeam to reset them so that their bottom surfaces are closely attached to the backing plates inside the crossbeam.

[0067] Operation 5.6: Continue to synchronously control the hydraulic devices at both the large and small mileage ends until the jack cylinders at the 4 positions all reach the maximum stroke.

[0068] Operation 5.7: Measure the actual elevation of the beam-slab at this time, and compare it with the designed elevation at the installation position to determine the total difference in beam lowering: Total difference in beam lowering = Current actual elevation - Designed elevation.

[0069] Operation 5.8: Based on the total difference in beam lowering and the limited stroke, determine the single-drop difference in elevation, the number of cycles, and the last-drop difference in elevation for the cyclic beam-lowering section; Among them, single-drop difference in elevation = Limited stroke; Last-drop difference in elevation = Total difference in beam lowering - (Single-drop difference in elevation × Number of cycles); The number of cycles is a positive integer.

[0070] Operation 5.9: Use a marker pen on the fine-rolled threaded rods, starting from the top surface of the top nut and with a limited stroke, mark the position of each cyclic stroke section and the position of the last beam lowering as an auxiliary identification.

[0071] The operations of this step and the setting of the stroke limit plate are as Figure 5 、 Figure 6As shown in the figure, operations 5.1 - 5.6 are to preset a 10 - mm stroke to avoid incomplete force conversion between the top nut and the positioning nut and the inability to manually turn the nut due to the deformation of the lifting and lowering beam support. Therefore, the single - time beam - lowering stroke of the jack in the cyclic beam - lowering section = single - time beam - lowering height difference + 10 mm, which is the maximum stroke of the jack; the last - time beam - lowering stroke of the jack = last - time beam - lowering height difference + 10 mm. The stroke limit plate is composed of two steel plates, welded to the inner side wall of the support cross - beam, and the middle gap is slightly larger than the diameter of the pull rod.

[0072] Step 6: Synchronously operate the hydraulic devices at both large - and small - mileage ends to cyclically lower the beam to the designed elevation position.

[0073] The specific operations in this link are as follows: Operation 6.1: Manually adjust and turn the 4 positioning nuts inside the cross - beam of the lifting and lowering beam support so that their top surfaces are in close contact with the bottom surface of the stroke limit plate.

[0074] Operation 6.2: Synchronously operate the hydraulic devices at both large - and small - mileage ends to fully retract the jack cylinders at 4 positions.

[0075] Operation 6.3: Manually adjust and turn the nut at the top of the fine - rolling threaded rod to the next stroke marking line, and synchronously operate the hydraulic devices at both large - and small - mileage ends to make the jack cylinder reach the maximum stroke, that is, the corresponding position of the top - nut marking.

[0076] Operation 6.4: Repeat operations 6.1 - 6.3 until the last - time beam - lowering stage.

[0077] Operation 6.5: Manually adjust and turn the 4 positioning nuts inside the cross - beam of the lifting and lowering beam support so that their top surfaces are in close contact with the bottom surface of the stroke limit plate.

[0078] Operation 6.6: Synchronously operate the hydraulic devices at both large - and small - mileage ends to slowly contract the jack cylinders at 4 positions, and at the same time monitor the change in the elevation of the beam slab. When the designed elevation is reached, maintain and pause the beam - lowering.

[0079] Operation 6.7: Manually adjust and turn the 4 positioning nuts inside the cross - beam of the lifting and lowering beam support so that they are roughly in the middle position between the stroke limit plate and the steel backing plate inside the cross - beam.

[0080] During the operation process of this link, it is necessary to combine manual monitoring of the change in the gap between the steel backing plate at the bottom of the four fine - rolling threaded rods and the balance beam. After operating the hydraulic system to fully retract all jack cylinders during the single - time beam - lowering stroke section, adjust the nut at the position where the gap becomes larger by turning, and re - mark the stroke position marked on this fine - rolling threaded rod.

[0081] Step 7: Alternately and cyclically operate to increase the single stroke, adjust the height of the temporary bearing, and the single stroke of the beam lowering, until the jack cylinder is fully retracted and the beam slab is no longer stressed between the lifting device, and the beam slab maintains the designed elevation position.

[0082] The specific operations in this link are as follows; Operation 7.1: After the last beam lowering is completed, measure the height differences between the bottom of the beam at the large and small mileage sides and the top surface of the capping beam respectively at this time.

[0083] Operation 7.2: Synchronously operate the hydraulic devices at the large and small mileage sides to extend the jack cylinders at the 4 points until the distance between the bottom of the beam and the top surface of the capping beam is greater than the height of the temporary bearing.

[0084] Operation 7.3: Based on the measured height differences between the bottom of the beam and the top surface of the capping beam, adjust the height of the temporary bearing, and symmetrically place it on the top surface of the capping beam with the longitudinal center line of the beam bottom as the reference at the large and small mileage sides. The leveling shim plates are padded on the top surface of the temporary bearing according to actual needs.

[0085] Operation 7.4: Synchronously operate the hydraulic devices at the large and small mileage sides to contract the jack cylinders at the 4 points until the elevation of the beam slab is stable and no longer drops.

[0086] Operation 7.5: Repeat Operations 7.2 to 7.4 until the jacks are fully retracted. Only relying on the support of the temporary bearings can make the elevation of the beam slab meet the installation requirements.

[0087] Step 8: After the installation of the beam slab lifting and lowering is completed, relieve the pressure of the hydraulic system and sequentially remove the hydraulic lifting device.

[0088] In this method, the synchronous layer of the hydraulic device foundation is the hardware foundation. The components such as the used hydraulic equipment and oil pipes must have unified specifications, the oil circuits are connected in parallel, the performance parameters of the configured hydraulic pump trucks must meet the working requirements, and the inlet three-way must be configured with a flow regulating valve.

[0089] The initial attitude coordination layer and the mechanical stroke limit layer are the keys.

[0090] Before the formal lifting and lowering of the beam, the initial attitude of the beam slab must be adjusted according to the designed longitudinal and transverse slopes to avoid disturbing the initially set synchronous operation due to attitude correction during the lifting and lowering of the beam; the placement position of the lifting and lowering support of the beam should be offset adjusted according to the placement position obtained by analyzing the initial attitude adjustment.

[0091] After completing the initial attitude adjustment and before the formal lifting and lowering of the beam, it is necessary to determine the number of cyclic beam lowering times and the last beam lowering stroke according to the measured total height difference of the beam lowering and the stroke value set by the stroke limit plate.

[0092] The relevant calculation formulas are as follows: Total height difference of beam lowering = current actual elevation - designed elevation.

[0093] The single-stage beam lowering height difference of the cyclic beam lowering section = the limit stroke; The final beam lowering height difference = the total beam lowering height difference - (the single-stage beam lowering height difference × the number of cycles); the number of cycles is a positive integer.

[0094] Considering the deformation of the lifting beam lowering support, the jack needs to be preset with a stroke of 10 mm. The stroke value set by the stroke limit plate can be set according to actual needs. In the introduction of the present invention, the limit stroke = the maximum stroke of the jack - 10 mm is taken as an example. Therefore: The single-stage beam lowering stroke of the jack in the cyclic beam lowering section = the single-stage beam lowering height difference + 10 mm, that is, the maximum stroke of the jack; the final beam lowering stroke of the jack = the final beam lowering height difference + 10 mm.

[0095] The manual fine-tuning compensation layer is a supplement to this set of multi-level synchronization control methods.

[0096] Embodiment 2 I. Site cleaning and material preparation First, clean the construction site to ensure that the lifting area is flat and unobstructed. At the same time, prepare the required hydraulic devices (including hydraulic pump stations, oil pipes, jacks, etc.), lifting equipment (such as balance beams, shackles, etc.), measuring tools (such as theodolites, feeler gauges, etc.) and other necessary materials.

[0097] II. Support installation and positioning According to the size, weight and lifting requirements of the precast beam slab, calculate and determine the placement position of the lifting beam lowering support. Use measuring tools to measure the actual straight-line distance and the current longitudinal slope of the beam slab lifting points, calculate the offset amount △L of the lifting beam lowering support according to the formula, and adjust the support position to the specified position. Ensure that the support is perpendicular to the beam slab, the center line is aligned with the longitudinal center line of the beam slab, and level the support cross beam by adding shims, etc.

[0098] III. Hydraulic device installation and commissioning Connect the hydraulic devices such as the hydraulic pump station, oil pipes, and jacks correctly in the way of a parallel oil circuit. During the connection process, ensure that all components have the same specifications and the oil circuit connections are tight without leakage. After the connection is completed, start the hydraulic pump truck, slowly boost the pressure according to the test pressure, and observe the telescopic synchronization of the jack cylinder and the tightness of the hydraulic circuit. Adjust the flow control valve of the oil inlet tee to achieve preliminary synchronization.

[0099] IV. Beam slab connection and trial lifting Use a shackle to firmly connect the precast beam slab to the balance beam. Subsequently, synchronously operate the hydraulic lifting devices at both the large and small mileage ends for a trial lift until the jack cylinders all extend to about half of their stroke, and maintain for no less than 5 minutes to observe changes in oil pressure, stroke, elevation, etc. After the trial lift shows no abnormalities, according to the current longitudinal slope of the beam slab and the required longitudinal slope for installation, individually operate the hydraulic lifting device on the side that needs to be lifted to adjust the longitudinal slope of the beam slab to the required longitudinal slope for installation, and complete the initial attitude adjustment.

[0100] V. Determine the stroke segmentation and the elevation difference of the last beam lowering After removing the original support frame of the beam slab, synchronously operate the hydraulic lifting device to fully retract the jack cylinders. After manually adjusting the position of the backing plate and nut at the top of the fine rolling threaded rod, set the stroke height limited by the stroke limit plate (limit stroke = maximum stroke of the jack - 10 mm). Based on the measured total elevation difference of beam lowering and the stroke value set by the stroke limit plate, determine the number of cyclic beam lowering times and the elevation difference of the last beam lowering, and mark the stroke positions required for each beam lowering on the fine rolling threaded rod.

[0101] VI. Formal lifting and cyclic beam lowering Perform cyclic beam lowering operations according to the determined stroke segmentation and the elevation difference of the last beam lowering. In each beam lowering stroke segment, after operating the hydraulic system to control all jack cylinders to fully retract, combine methods such as manual monitoring of the elevation deviation of the beam slab and the change in the gap between the balance beam and the bottom steel backing plate to judge the degree of synchronous deviation. If the deviation is large, take manual fine-tuning compensation measures for adjustment. Repeat this process in a cycle until the beam slab is lifted to the designed elevation position.

[0102] VII. Adjust the temporary support and the final beam lowering After the beam slab is lifted to the designed elevation position, alternately and cyclically operate to lift a single stroke, adjust the height of the temporary support, and lower the beam by a single stroke. Achieve the smooth beam lowering of the beam slab by continuously adjusting the height of the temporary support and operating the hydraulic lifting device. Until the jack cylinders are fully retracted and there is no more force between the beam slab and the lifting device, the beam slab is maintained at the designed elevation position.

[0103] VIII. Completion of construction and removal of equipment After the installation of the beam slab is completed, relieve the pressure of the hydraulic system, and sequentially remove the construction equipment and materials such as the hydraulic lifting device and the temporary support. Clean the construction site to ensure no debris and safety hazards are left.

[0104] By adopting the mechanical - manual composite control method described in the present invention, the hydraulic lifting operation of the precast beam slab in this urban viaduct construction project has achieved high-precision synchronous control, meeting the synchronous accuracy requirement of ±3 mm level. No safety accidents and quality problems occurred during the construction process, effectively improving the construction efficiency and economic benefits. At the same time, this method is simple to operate and convenient to maintain.

[0105] The present invention only needs to rely on small and conventional hydraulic devices and fittings to achieve a significant improvement in the synchronous control of multiple cylinders and meet the construction requirements; it has the advantages of flexible handling, quick assembly, and low configuration cost. Moreover, for the synchronous control of hydraulic lifting operations, the present invention integrates initial attitude coordination, basic synchronization of hydraulic devices, mechanical stroke limitation, and manual fine-tuning compensation to establish a multi-level synchronous control system, strictly control various specific pre-control and process control points, and achieve high-precision and high-synchronization installation of precast beam and slab lifting and lowering beams in complex and restricted environments economically.

[0106] The above are only the embodiments provided by this application and are not used to limit this application. Although this application has been described in detail with reference to the embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims

1. A human-machine composite control method for high-precision hydraulic synchronous lifting of precast beam and slab of bridges, characterized in that: The method realizes synchronization guarantee through a multi-level synchronization control system that integrates pre-error elimination and process error suppression; the multi-level synchronization control system includes an initial posture coordination layer, a hydraulic system basic synchronization layer, a mechanical stroke limitation layer and a manual fine-tuning compensation layer, and combines mechanical devices with manual operations to achieve high-precision, high-synchronization control of bridge prefabricated beams during the hydraulic lifting process.

2. The human-machine composite control method for high-precision hydraulic synchronous lifting of precast beam and slab of bridge according to claim 1, characterized in that: The initial posture coordination layer is specifically: Measure the actual straight-line distance and current longitudinal slope of the beam-slab hanging points; calculate and determine the placement of the beam-dropping bracket based on the actual and designed data of beam length, hanging point position, and longitudinal slope, so as to adjust the initial posture of the beam-slab to the design requirements and eliminate the synchronization deviation caused by the longitudinal slope of the beam-slab; Among them, the calculation formula for determining the offset of the placement position of the lifting beam bracket is: Offset △L=(L1-L2) / 2=L×[cos(a1)-cos(a2)] / 2; △L: indicates the offset; L: represents the straight-line distance between the hanging points at both ends of the beam and slab; L1: represents the horizontal distance between the two end hanging points of the beam slab under the longitudinal slope of the beam slab before lifting; L2: represents the horizontal distance between the two end hanging points of the beam after adjusting the initial posture; a1: represents the horizontal angle corresponding to the longitudinal slope of the beam plate before lifting; a2: It indicates the horizontal angle corresponding to the longitudinal slope of the beam after being put into place, that is, the horizontal angle after the initial posture needs to be adjusted.

3. A human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge beams and slabs according to claim 1, characterized in that: The basic synchronization layer of the hydraulic system is specifically as follows: using hydraulic pump stations, oil pipes, jacks and other hydraulic devices of uniform specifications; adopting a dual-pump four-cylinder diversion system, a single oil pump synchronously drives two jacks on the same side, and a three-way diverter with a flow adjustment handle is used to achieve balanced distribution of oil, so as to improve the synchronization of the hydraulic system.

4. A human-machine composite control method for high-precision hydraulic synchronous lifting of precast girders and slabs of bridges according to claim 1, characterized in that: The mechanical stroke limiting layer is specifically as follows: the total height difference of the lifting and dropping beam is evenly divided into a number of equal stroke segments within the effective stroke of the jack, except for the last beam dropping stroke; a stroke limit plate is set to ensure that the actual stroke of each point in each stroke segment is consistent during four-point lifting, so as to reduce cumulative errors and ensure synchronization.

5. A human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge girders and slabs according to claim 4, characterized in that: After completing the initial posture adjustment and formally lifting and dropping the beam, it is necessary to determine the number of cyclic beam drops and the last beam drop stroke based on the measured total height difference of the beam drop and the stroke value set by the stroke limit plate; Total height difference of dropped beam = current actual elevation - design elevation.

6. The height difference of a single beam drop in the cycle beam drop section = the limit stroke; The height difference of the last beam drop = the total height difference of the beam drop - (the height difference of a single beam drop × the number of cycles); the number of cycles is a positive integer; Considering the deformation of the lifting beam drop bracket, the jack needs to be preset with a stroke of 10mm. The single beam drop stroke of the jack in the cycle beam drop section = the single beam drop height difference + 10mm, that is, the maximum stroke of the jack; The last beam-dropping stroke of the jack = the last beam-dropping height difference + 10mm.

7. A human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge girders and slabs according to claim 1, characterized in that: The manual fine-tuning compensation layer is specifically as follows: during the lifting process, the synchronization of the four points of the beam and slab is manually observed; when the synchronization deviation is large, manual fine-tuning measures are immediately taken, such as adjusting the oil pressure or stroke of the jack, to ensure that the beam and slab can be lifted smoothly and synchronously to the designed elevation position.

8. A human-machine composite control method for high-precision hydraulic synchronous lifting of precast bridge girders and slabs according to any one of claims 1-6, characterized in that The method also includes the following operation process: Step 1: Clean up the site and prepare materials; Step 2: Measure and place the beam lifting and lowering support, where the placement position of the beam lifting and lowering support is determined according to the offset calculation formula; Step 3: Install the complete set of lifting equipment such as hydraulic lifting devices and balance beams, and conduct commissioning and inspection; Step 4: Connect the beam slab to the balance beam, conduct a trial lift and adjust the initial attitude; Step 5: Determine the stroke segments and the elevation difference of the last beam lowering; Step 6: Synchronously operate the hydraulic device and gradually lift it to the designed elevation position according to the preset stroke segments; Step 7: During the lifting process, continuously conduct manual observation and fine-tuning compensation to ensure synchronism; Step 8: After the lifting is completed, conduct necessary adjustments and finishing work, such as adjusting the height of the temporary support and removing the hydraulic lifting device.

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