Method for erecting lower-layer U beam of double-layer viaduct

Abstract

The invention provides a method for erecting a lower-layer U-shaped beam of a double-layer viaduct, and belongs to the technical field of U-shaped beam erecting, a beam transporting flatcar, a bridge erecting machine, a supporting mechanism and a balance mechanism are included, and the method specifically comprises the steps that S1, the beam transporting flatcar transports the U-shaped beam to the front span of the erecting position; s2, enabling a lifting point at the front end of the U-shaped beam to exceed an upper cover beam of an erected span; s3, a front crown block of the bridge erecting machine moves longitudinally, and the front crown block of the bridge erecting machine and the hoisting point are located on the same plumb line; s4, the U-shaped beam is conveyed forwards; s6, after the U-shaped beam is stabilized, the beam transporting flatcar and the beam transporting trolley move back; and S7, the bridge girder erection machine moves longitudinally and transversely until the distance between the U-shaped beam to be erected and the front end of the upper cover beam of the erected span is 5-10 cm, the front crown block, the rear crown block and the traction unit fall the beams synchronously, when the distance between the U-shaped beam to be erected and the upper end of the upper cover beam of the erected span is 2-5 cm, the U-shaped beam to be erected is aligned to the front end of the upper cover beam of the erected span, and the U-shaped beam is installed in place. The U-shaped beam can be effectively prevented from being deformed and damaged in the hoisting process.

Description

Technical Field

[0001] The invention relates to the technical field of U-beam erection, and in particular to a method for erecting a lower-layer U-beam of a double-deck viaduct. Background Art

[0002] Traditional elevated precast beam hoisting generally involves relatively heavy and large beams, and the main focus during the hoisting process is on the stability and verticality of the beams. However, with the increasing complexity of construction projects, especially in the construction of double-deck elevated roads, precast U-shaped beams face more severe technical challenges during the hoisting process due to their unique structural characteristics.

[0003] Prefabricated U-shaped beams use pre-stressed thin-walled components. The width of a single U-shaped beam reaches 510cm, the thinnest wall thickness is only 26.5cm, and its weight is as high as 211.25t. These structural features make the U-shaped beam very easy to be twisted and deformed during the hoisting process. The thin-walled structure has poor rigidity and is easily deformed or damaged locally by external forces during the hoisting process. Especially in terms of the arrangement of the lifting points of the hoisting equipment and the posture control of the beam body, if the operation is improper, the beam body may be unevenly stressed, resulting in serious distortion, cracks or surface damage, affecting the construction progress and the safety of the beam body.

[0004] At present, the existing elevated prefabricated beam lifting technology has not completely solved this problem. Especially when dealing with U-shaped beam lifting, how to effectively avoid distortion, deformation, damage and improve lifting efficiency is still a hot topic in technical research. Summary of the invention

[0005] The object of the present invention is to provide a method for erecting a U-beam on the lower level of a double-deck viaduct, which can effectively prevent the U-beam from being deformed and damaged during the hoisting process.

[0006] The embodiments of the present invention are implemented by the following technical solutions: A method for erecting a lower U-beam of a double-deck viaduct comprises a beam transport flat car, a bridge erection machine, a support mechanism and a balancing mechanism, and the specific steps include: S1. The beam transport flat car transports the U-shaped beam to the span before the erection position, and evenly installs multiple sets of support mechanisms along the length direction of the U-shaped beam, so that the support mechanisms are horizontally supported on both sides of the inner wall of the U-shaped beam; S2, the beam transport flat car moves longitudinally so that the front end lifting point of the U-shaped beam exceeds the upper cover beam of the erection span; S3. The front crane of the bridge erection machine is moved longitudinally, so that the front crane of the bridge erection machine and the lifting point are on the same plumb line, the upper support unit of the balancing mechanism is installed on the upper U-beam of the viaduct, and the lower support unit of the balancing mechanism is installed at the bottom of the beam body of the U-beam to be erected. The upper support unit and the lower support unit are connected by a traction unit, and the hook of the front crane is connected to the front lifting point of the U-beam; S4. The front crane of the bridge erecting machine moves forward longitudinally, and the beam transport trolley above the beam transport flat car moves longitudinally synchronously to transport the U-shaped beam forward to the upper cover beam where the rear end lifting point of the U-shaped beam exceeds the erection span. The rear crane position of the bridge erecting machine is adjusted so that the hook of the rear crane and the rear end lifting point of the U-shaped beam are on the same plumb line, and the hook of the rear crane is connected to the lifting point; S5, the front crane, the rear crane and the traction unit are lifted synchronously, so that the U-shaped beam is 10cm away from the beam transport trolley, and then the lifting is carried out to observe whether there is any danger source; S6. After the U-shaped beam is stable, the beam transport flat car and beam transport trolley move backwards and the beam transport flat car and beam transport trolley exit the site; S7. Move the bridge-erecting machine longitudinally and transversely to adjust the position of the U-shaped beam until the U-shaped beam to be erected is 5cm-10cm away from the front end of the upper cover beam of the erection span. The front crane, rear crane and traction unit drop the beam synchronously. When the U-shaped beam to be erected is 2cm-5cm away from the upper end of the pier, align the U-shaped beam to be erected with the front end of the upper cover beam of the erection span. The front crane, rear crane and traction unit drop the beam synchronously to the upper end support of the bridge section to install the U-shaped beam in place.

[0007] Furthermore, the supporting mechanism includes a bidirectional cylinder, an extension rod and a support plate. The bidirectional cylinder is horizontally fixedly installed inside the U-shaped beam through a bracket. The extension rod is provided with a pair of piston rods that are respectively fixed at both ends of the bidirectional cylinder. The support plate is fixedly provided at the end of the extension rod and is used to support the positions on both sides of the inner wall of the U-shaped beam.

[0008] Furthermore, a hard rubber pad is provided between the support plate and the inner wall of the U-shaped beam.

[0009] Furthermore, the upper support unit includes a sliding frame and a roller. The sliding frame is arranged across the upper U-beam of the viaduct, and the roller is fixedly installed at the bottom of the sliding frame.

[0010] Furthermore, the lower support unit includes an outer frame and abutment wheels, the outer frame is clamped at the bottom wall and the side walls of the U-shaped beam, a plurality of abutment wheels are provided and installed on the outer frame, and the abutment wheels are abutted against the bottom wall and the side walls of the U-shaped beam.

[0011] Furthermore, the wheelbases of the adjacent abutting wheels at the bottom of the outer frame gradually increase from the middle to both ends.

[0012] Furthermore, a limit frame can be detachably provided on the outer frame, the limit frame is abutted against the top wall of the U-shaped beam, a pair of limit rods are fixedly provided on the limit frame, and the limit rods are respectively abutted against positions on both sides of the inner wall of the U-shaped beam.

[0013] Furthermore, the traction unit includes a wire traction machine, a pair of which are arranged on both sides of the sliding frame, the wire traction machine is fixedly arranged on the sliding frame, and output ends of the pair of wire traction machines are respectively fixedly connected to both sides of the top of the outer frame.

[0014] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects: 1. The present invention can effectively solve the problem of deformation or damage of the U-shaped beam during the hoisting process in the traditional erection method by utilizing the method for erecting the lower U-shaped beam of the double-deck viaduct. Specifically, the method can accurately control the position of the lifting point through the cooperation of the beam transport flat car and the bridge erection machine, making the erection process more stable. By evenly installing multiple sets of support mechanisms on both sides of the U-shaped beam, the force on the beam body is effectively dispersed, avoiding local deformation during the hoisting process.

[0015] In addition, the design of the balancing mechanism further improves the accuracy of the erection, especially during the hoisting process, the synchronous operation of the front and rear cranes, and the precise control of the traction unit ensure that the U-beam is always in a stable and balanced state during the hoisting and installation process. Through the mutual cooperation of the upper and lower support units, the support force can be evenly applied during the hoisting process, avoiding deformation or damage of the beam body caused by uneven force.

[0016] In general, the stability and safety of the U-beam during the erection process are ensured, which significantly improves construction efficiency and reduces risks.

[0017] 2. The present invention has significant advantages and beneficial effects by setting up a support mechanism and utilizing the reasonable design of a two-way cylinder, an extension rod and a support plate. First, the two-way action of the two-way cylinder enables the support plate to evenly apply the support force, ensuring the stability of the U-shaped beam during the hoisting process and avoiding local deformation or tilting of the U-shaped beam due to uneven force. Secondly, the design of the extension rod avoids the use of a longer two-way cylinder piston rod, which facilitates overall transportation. The support plate can be flexibly adjusted on both sides of the inner wall of the U-shaped beam, providing an efficient support solution, adapting to complex erection environments, and improving work efficiency. The precise control of the support mechanism further reduces the risk of deformation or damage to the beam body, especially during the hoisting process, effectively avoiding construction safety issues caused by uneven support force. In addition, the support mechanism is simple and reliable in structure, and the support position is accurately controlled by the cylinder, making the support system more convenient and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 The present invention aims to show a schematic diagram of the structure of a beam transport flat car transporting a beam to a span before erection; Figure 2 The present invention aims to show the structural schematic diagram of the longitudinal movement of the front crane of the bridge erection machine, the longitudinal movement of the beam transport flat car, and the connection between the front crane and the U-beam hanging point; Figure 3 This is a schematic diagram of the structure of the invention to show the synchronous lifting of the front crane and the rear crane; Figure 4 This is a schematic diagram of the structure of the present invention to show that the U-beam is installed in place; Figure 5 The present invention is intended to show a side view of a balancing mechanism and a supporting mechanism installed on a U-shaped beam; Figure 6 This is a schematic diagram of the structure of the upper support unit and the traction unit of the present invention; Icons: 1- beam transport flat car, 11- beam transport trolley, 2- bridge erecting machine, 21- front crane, 22- rear crane, 3- supporting mechanism, 31- bidirectional cylinder, 311- bracket, 33- extension rod, 32- supporting plate, 34- hard rubber pad, 4- balancing mechanism, 41- upper supporting unit, 411- sliding frame, 412- roller, 42- lower supporting unit, 421- outer frame, 422- abutment wheel, 43- traction unit, 431- wire traction machine, 5- limit frame, 51- limit rod, 6- upper cover beam of erection span, 7- U-shaped beam. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0022] The following is further described in conjunction with specific embodiments. Figure 1-Figure 6 As shown, the present invention is a method for erecting a U-beam on the lower layer of a double-deck viaduct, comprising a beam transport flat car 1, a bridge erection machine 2, a support mechanism 3 and a balancing mechanism 4, and the specific steps include: S1. The beam transport flat car 1 transports the U-shaped beam 7 to the span before the erection position, and evenly installs multiple sets of support mechanisms 3 along the length direction of the U-shaped beam 7, so that the support mechanisms 3 are horizontally supported on both sides of the inner wall of the U-shaped beam 7 to ensure the stability of the U-shaped beam 7 during transportation and avoid damage caused by uneven force or vibration; S2, the beam transport flat car 1 moves longitudinally, so that the front end lifting point of the U-shaped beam 7 exceeds the upper cover beam 6 of the erection span. It is necessary to ensure that the front end of the U-shaped beam 7 can accurately exceed the preset position through precise control, so as to prepare for the subsequent erection operation; S3, the front crane 21 of the bridge erecting machine 2 is moved longitudinally, so that the front crane 21 of the bridge erecting machine 2 and the lifting point are on the same plumb line, the upper support unit 41 of the balancing mechanism 4 is installed on the upper U-beam of the viaduct, the lower support unit 42 of the balancing mechanism 4 is installed at the bottom of the beam body of the U-shaped beam 7 to be erected, the upper support unit 41 and the lower support unit 42 are connected by the traction unit 43, and the hook of the front crane 21 is connected to the front lifting point of the U-shaped beam 7; the front lifting point of the U-shaped beam 7 is specifically a lifting ring prefabricated at the front end of the U-shaped beam 7; S4, the front crane 21 of the bridge erecting machine 2 moves forward longitudinally, and the beam transport trolley 11 above the beam transport flat car 1 moves longitudinally synchronously to transport the U-shaped beam 7 forward to the upper cover beam 6 where the rear end lifting point of the U-shaped beam 7 exceeds the erection span, and the position of the rear crane 22 of the bridge erecting machine 2 is adjusted so that the hook of the rear crane 22 and the rear end lifting point of the U-shaped beam 7 are on the same plumb line, and the hook of the rear crane 22 is connected to the lifting point; the rear lifting point of the U-shaped beam 7 is specifically a lifting ring prefabricated at the rear end of the U-shaped beam 7; S5, the front crane 21, the rear crane 22 and the traction unit 43 are lifted synchronously, so that the U-shaped beam 7 is separated from the beam transport trolley 1110cm, and the lifting is carried out to observe whether there is any danger source; the traction motors, wire ropes, hooks, etc. of the front crane 21 and the rear crane 22 work together to ensure that the U-shaped beam 7 is stable and safe during the lifting process; After S6 and the U-shaped beam 7 are stable, the beam transport flat car 1 and the beam transport trolley 11 move backwards, and the beam transport flat car 1 and the beam transport trolley 11 withdraw from the site and prepare to withdraw from the erection area to make room for subsequent operations; S7, the bridge erection machine 2 moves longitudinally and transversely to adjust the position of the U-shaped beam 7 until the U-shaped beam 7 to be erected is 5cm-10cm away from the front end of the upper cover beam 6 of the erection span, the front crane 21, the rear crane 22 and the traction unit 43 drop the beam synchronously, and when the U-shaped beam 7 to be erected is 2cm-5cm away from the upper end of the pier, the U-shaped beam 7 to be erected is aligned with the front end of the upper cover beam 6 of the erection span, the front crane 21, the rear crane 22 and the traction unit 43 drop the beam synchronously to the upper end support of the bridge section, and install the U-shaped beam 7 in place; in actual operation, the U-shaped beam 7 to be erected is generally about 2cm away from the upper end of the pier, the U-shaped beam 7 to be erected is aligned with the front end of the upper cover beam 6 of the erection span, and the front crane 21, the rear crane 22 and the traction unit 43 are controlled to drop the beam synchronously to the upper end support of the bridge section. Through precise control, the U-shaped beam 7 to be erected is ensured to be aligned with the front end of the upper cover beam 6 of the erection span. This distance of docking can not only avoid collision between the U-shaped beam 7 and the upper cover beam 6 of the erection span during the erection process, but also significantly improve the erection efficiency. It can reduce unnecessary fine-tuning, shorten the erection time, and improve construction efficiency. In addition, accurate docking allows the U-shaped beam 7 to be erected to be better aligned with the upper cover beam 6 of the erection span, ensuring the installation accuracy of the U-shaped beam 7, thereby improving the overall stability and construction quality of the structure.

[0023] Reference Figure 5 As shown, multiple groups of support mechanisms 3 are evenly installed along the length direction of the U-shaped beam 7 to ensure the uniform distribution of the supporting force. Each group of support mechanisms 3 includes a two-way cylinder 31, an extension rod 33 and a support plate 32. Specifically, the two-way cylinder 31 is horizontally fixedly installed inside the U-shaped beam 7 through a bracket 311 to ensure the stability and supporting force of the cylinder. The extension rod 33 is set as a pair and is respectively fixed at both ends of the piston rod of the two-way cylinder 31 to achieve stable adjustment and support of the support plate 32. The support plate 32 is fixed to the end of the extension rod 33, and is used to support the positions on both sides of the inner wall of the U-shaped beam 7, thereby effectively resisting the weight of the U-shaped beam 7 and maintaining its position.

[0024] A hard rubber pad 34 is provided between the support plate 32 and the inner wall of the U-shaped beam 7, which plays a role of buffering and protection. The hard rubber pad 34 can effectively reduce the friction between the support plate 32 and the inner wall of the U-shaped beam 7, and avoid surface wear or damage caused by direct contact. This design not only improves the stability of the structure, but also prolongs the service life of the equipment and reduces maintenance costs.

[0025] Through the cooperation of the bidirectional cylinder 31, the extension rod 33 and the support plate 32, the support mechanism 3 can accurately adjust the support force of the U-shaped beam 7 and ensure its stable support during the erection process. The adjustment function of the bidirectional cylinder 31 enables the support mechanism 3 to adjust the position of the support plate 32 as needed, thereby flexibly responding to different lifting and transportation requirements.

[0026] In general, this embodiment ensures the stable support of the U-shaped beam 7 during the erection process by properly arranging the support mechanism 3 and the application of the hard rubber pad 34, reduces friction, prevents damage, and improves work efficiency and the service life of the equipment. This design makes the hoisting operation of the U-shaped beam 7 more stable and safe, and easy to adjust and maintain.

[0027] Reference Figure 4 and Figure 5 As shown, the upper support unit 41 and the lower support unit 42 are designed to work together to ensure the stability and safety of the U-shaped beam 7 during the hoisting process.

[0028] The upper support unit 41 includes a sliding frame 411 and a roller 412. The sliding frame 411 is arranged across the upper surface of the upper U-beam of the viaduct, and the roller 412 is fixedly installed at the bottom of the sliding frame 411. The sliding frame 411 can slide smoothly under the action of the roller 412. This design enables the upper support unit 411 to flexibly adapt to the balance required for the U-beam 7 during the lifting process due to mechanical changes or position adjustments, and reduce deformation or damage caused by uneven force. The presence of the roller 412 not only provides smooth sliding support, but also ensures that the sliding frame 411 always maintains a smooth and controlled movement during the lifting process, avoiding damage to the U-beam 7 due to instability.

[0029] The lower support unit 42 includes an outer frame 421 and a plurality of abutment wheels 422. The outer frame 421 is clamped at the bottom wall and the side walls of the U-shaped beam 7 to ensure that the outer frame 421 can tightly fix the U-shaped beam 7 and provide stable support during the hoisting process. The abutment wheels 422 are installed on the outer frame 421 and form a close contact with the bottom wall and the side walls of the U-shaped beam 7. The number and position design of the abutment wheels 422 enable the outer frame 421 to slide along the length direction of the U-shaped beam 7 under their action, and flexibly adjust the support position, so as to better adapt to the balance changes of the U-shaped beam 7 during the hoisting process. This design can effectively prevent the U-shaped beam 7 from being deformed or damaged due to uneven force or improper operation.

[0030] Through the cooperation of the upper support unit 41 and the lower support unit 42, the support force of the U-shaped beam 7 is evenly distributed during the entire hoisting process, preventing the beam from being deformed or damaged due to unbalanced load or improper operation during hoisting and transportation. The upper support unit 41 provides stable sliding support, while the lower support unit 42 provides effective support and sliding adjustment, ensuring the smooth hoisting of the U-shaped beam 7.

[0031] Reference Figure 5As shown, the wheelbase of the adjacent abutment wheels 422 at the bottom of the outer frame 421 gradually increases from the middle to the two ends. Since the mass of the middle part of the U-shaped beam 7 is relatively large, more abutment wheels 422 are added in the middle area. The purpose of this design is to effectively disperse the large mass of the middle part of the U-shaped beam 7, ensure a more even distribution of the bearing capacity, and avoid deformation or instability of the beam body caused by excessive local force.

[0032] In the middle of the U-shaped beam 7, increasing the number of abutment wheels 422 can balance the force, reduce the burden of each abutment wheel 422, and improve the stability of the contact surface between the outer frame 421 and the U-shaped beam 7. This not only ensures that the supporting force of the U-shaped beam 7 is sufficient during the erection process, but also effectively prevents the deviation or tilt caused by uneven mass distribution during the hoisting process.

[0033] As the wheelbase increases from the middle to both ends, the force on the outer frame 421 gradually expands to both ends, forming a reasonable mechanical distribution. In this way, at both ends of the U-shaped beam 7, too many abutment wheels 422 are reduced, which helps to reduce unnecessary friction, thereby improving the sliding property and operational flexibility of the U-shaped beam 7 during the hoisting process.

[0034] In general, this embodiment effectively supports the larger mass in the middle by increasing the number of abutment wheels 422 in the middle area of ​​the U-shaped beam 7, while avoiding the friction resistance caused by too many abutment wheels 422, thereby ensuring the stability, smooth movement and precise lifting of the U-shaped beam 7. This design makes the erection operation more efficient and safer, and reduces the potential risks caused by uneven force.

[0035] Reference Figure 5 As shown, the outer frame 421 is detachably mounted with a limit frame 5 by bolts, so that the outer frame 421 can be easily mounted on the U-shaped beam 7. The design of the limit frame 5 enables the outer frame 421 to be stably matched with the U-shaped beam 7, simplifies the installation process, and improves the installation accuracy. The limit frame 5 abuts against the top wall of the U-shaped beam 7 to ensure that the position of the outer frame 421 is fixed during installation, and avoids unnecessary movement or offset of the outer frame 421 during the installation process.

[0036] A pair of limit rods 51 are fixedly welded on the limit frame 5, and the limit rods 51 are respectively in contact with the inner walls of the U-shaped beam 7. The function of the limit rods 51 is to provide effective support for the U-shaped beam 7 to prevent it from deforming or shifting toward the middle during the erection process. This design ensures that the forces on both sides of the U-shaped beam 7 are balanced by evenly applying the limit force, thereby avoiding uneven deformation or tilting of the beam during the hoisting process.

[0037] The cooperation between the limit frame 5 and the limit rod 51 can effectively constrain the shape of the U-shaped beam 7, ensuring that it always maintains the correct position and stable state during the erection process. Through this structure, the deformation of the beam body caused by the external uneven force can be reduced, thereby improving the safety and accuracy of the hoisting operation.

[0038] The detachable design of the limiting frame 5 and the limiting rod 51 also provides convenience for the subsequent adjustment, maintenance and transportation of the U-shaped beam 7. Through the bolt connection, it can be quickly disassembled and installed, reducing the workload during engineering adjustment and improving work efficiency.

[0039] Reference Figure 5 and Figure 6 As shown, the traction unit 43 includes a pair of steel wire traction machines 431, and the steel wire traction machines 431 are respectively arranged on both sides of the sliding frame 411 and fixedly mounted on the sliding frame 411. The output ends of each steel wire traction machine 431 are respectively fixedly connected to both sides of the top of the outer frame 421. It should be particularly emphasized that the traction motor of the steel wire traction machine 431 is started synchronously with the traction motors of the front crane 21 and the rear crane 22, so that the steel wire rope can be lowered synchronously, thereby ensuring the smooth descent of the U-shaped beam 7 during the erection process, and avoiding the displacement or deformation of the beam body due to uneven speed or improper control.

[0040] In this embodiment, the traction motor of the wire traction machine 431 is synchronously controlled with the traction motors of the front crane 21 and the rear crane 22 to ensure the coordinated actions of the front and rear hoisting devices, thereby maintaining the verticality and stability of the U-shaped beam 7. Through this synchronous start control, the traction unit 43 can smoothly drive the wire rope to be lowered, ensuring the stability and accuracy of the U-shaped beam 7 during the installation process.

[0041] In addition, in different embodiments, the connection mode between the steel wire rope of the steel wire traction machine 431 and the outer frame 421 can be flexibly designed as needed. For example, a movable pulley block can be used for connection transmission to reduce the load of the traction motor and improve the transmission efficiency of the traction force. Through the cooperation of the movable pulley block, the steel wire rope can be lowered more smoothly, while reducing the power consumption of the traction motor, avoiding energy waste and equipment loss caused by excessive power of the traction motor. This design can optimize the performance of the overall traction system, improve control accuracy and operational stability, and thus improve construction efficiency and safety.

[0042] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for erecting a U-beam on the lower level of a double-deck viaduct, comprising a beam transport flat car (1), a bridge erection machine (2), a support mechanism (3) and a balancing mechanism (4), characterized in that: The specific steps include: S1, a beam transport flat car (1) transports the U-shaped beam (7) to the span before the erection position, and evenly installs multiple sets of support mechanisms (3) along the length direction of the U-shaped beam (7), so that the support mechanisms (3) are horizontally supported on both sides of the inner wall of the U-shaped beam (7); S2, the beam transport flat car (1) moves longitudinally so that the front end lifting point of the U-shaped beam (7) exceeds the upper cover beam (6) of the erection span; S3, the front crane (21) of the bridge erecting machine (2) is longitudinally moved so that the front crane (21) of the bridge erecting machine (2) and the suspension point are on the same plumb line, the upper support unit (41) of the balancing mechanism (4) is installed on the upper U-beam of the viaduct, the lower support unit (42) of the balancing mechanism (4) is installed at the bottom of the beam body of the U-shaped beam (7) to be erected, the upper support unit (41) and the lower support unit (42) are connected by a traction unit (43), and at the same time, the hook of the front crane (21) is connected to the front suspension point of the U-shaped beam (7); S4, the front trolley (21) of the bridge erecting machine (2) moves forward longitudinally, and the beam transport trolley (11) above the beam transport flat car (1) moves longitudinally synchronously to transport the U-shaped beam (7) forward until the rear end suspension point of the U-shaped beam (7) exceeds the upper cover beam (6) of the erection span, and the position of the rear trolley (22) of the bridge erecting machine (2) is adjusted so that the hook of the rear trolley (22) and the rear end suspension point of the U-shaped beam (7) are on the same plumb line, and the hook of the rear trolley (22) is connected to the suspension point; S5, the front crane (21), the rear crane (22) and the traction unit (43) are lifted synchronously to separate the U-shaped beam (7) from the beam transport trolley (11) by 10 cm, and then the lifting is performed to observe whether there is any danger source; S6. After the U-shaped beam (7) is stable, the beam transport flat car (1) and the beam transport trolley (11) move backwards, and the beam transport flat car (1) and the beam transport trolley (11) exit the site; S7, the bridge erection machine (2) moves longitudinally and transversely to adjust the position of the U-shaped beam (7) until the U-shaped beam (7) to be erected is 5 cm-10 cm away from the front end of the upper cover beam (6) of the erection span, the front crane (21), the rear crane (22) and the traction unit (43) synchronously drop the beam, and when the U-shaped beam (7) to be erected is 2 cm-5 cm away from the upper end of the bridge pier, the U-shaped beam (7) to be erected is aligned with the front end of the upper cover beam (6) of the erection span, and the front crane (21), the rear crane (22) and the traction unit (43) then synchronously drop the beam to the upper end support of the bridge section to install the U-shaped beam (7) in place.

2. The method for erecting the lower U-beam of a double-deck viaduct according to claim 1, characterized in that: The support mechanism (3) comprises a bidirectional cylinder (31), an extension rod (33) and a support plate (32); the bidirectional cylinder (31) is horizontally fixedly installed inside the U-shaped beam (7) through a bracket (311); the extension rod (33) is provided with a pair of piston rods which are respectively fixedly arranged at both ends of the bidirectional cylinder (31); the support plate (32) is fixedly arranged at the end of the extension rod (33) and is used for supporting the positions on both sides of the inner wall of the U-shaped beam (7).

3. The method for erecting the lower U-beam of a double-deck viaduct according to claim 2 is characterized in that: A hard rubber pad (34) is provided between the support plate (32) and the inner wall of the U-shaped beam (7).

4. The method for erecting the lower U-beam of a double-deck viaduct according to claim 2, characterized in that: The upper support unit (41) comprises a sliding frame (411) and a roller (412); the sliding frame (411) is arranged across the upper U-beam of the viaduct, and the roller (412) is fixedly installed at the bottom of the sliding frame (411).

5. The method for erecting the lower U-beam of a double-deck viaduct according to claim 4, characterized in that: The lower support unit (42) comprises an outer frame (421) and abutment wheels (422); the outer frame (421) is clamped at the bottom wall and the side walls on both sides of the U-shaped beam (7); a plurality of abutment wheels (422) are provided and mounted on the outer frame (421); the abutment wheels (422) are abutted against the bottom wall and the side walls on both sides of the U-shaped beam (7).

6. The method for erecting the lower U-beam of a double-deck viaduct according to claim 5, characterized in that: The wheelbase of the adjacent abutting wheels (422) at the bottom of the outer frame (421) gradually increases from the middle to both ends.

7. The method for erecting the lower U-beam of a double-deck viaduct according to claim 5, characterized in that: A limit frame (5) can also be detachably provided on the outer frame (421), the limit frame (5) being arranged in contact with the top wall of the U-shaped beam (7), a pair of limit rods (51) being fixedly provided on the limit frame (5), the limit rods (51) respectively being in contact with positions on both sides of the inner wall of the U-shaped beam (7).

8. The method for erecting the lower U-beam of a double-deck viaduct according to claim 5, characterized in that: The traction unit (43) comprises a steel wire traction machine (431), a pair of the steel wire traction machines (431) are provided and are located on both sides of the sliding frame (411), the steel wire traction machines (431) are fixedly arranged on the sliding frame (411), and the output ends of the pair of steel wire traction machines (431) are respectively fixedly connected to both sides of the top of the outer frame (421).

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