Construction method for erecting small-radius bridge precast beam in mountainous area

Abstract

The application provides a construction method for erecting a precast beam of a small-radius bridge in a mountainous area, comprising the steps of assembling a bridge-erecting machine, widening a bent cap, passing the bridge-erecting machine through a hole, transporting the beam on a bridge deck, and erecting the beam by a beam lifting device. The guide beam and the middle leg assembly of the existing bridge-erecting machine are usually connected by bolts. During construction, the connecting bolts between the guide beam and the middle leg assembly can be slightly loosened, the differential speed of the two guide beams is controlled by a longitudinal displacement motor, a small angle is formed between the guide beam and the middle leg assembly, the maximum turning angle of the bridge-erecting machine is adjusted, the tail end of the guide beam is stably supported, the construction method can be applied to the erection of precast beams of small-radius and large-cross-slope bridges on sections of secondary and tertiary roads or high-grade road interchanges in mountainous and hilly areas, and the construction method is suitable for the erection of precast beams of bridges with limited bridgehead sites and high assembly difficulty of the bridge-erecting machine. Moreover, the construction method can use the existing bridge-erecting machine on the market for construction, and it is not necessary to purchase or modify the bridge-erecting machine.

Description

Technical Field

[0001] This invention relates to bridge construction technology, specifically to a construction method for erecting small-radius precast bridge beams in mountainous areas. Background Technology

[0002] In mountainous and hilly areas, on sections of secondary and tertiary highways or interchanges of high-grade highways, bridges with small curve radii are often present due to the influence of the terrain. When crossing deep ravines and canyons, the construction safety risks of using cast-in-place beams for the superstructure of the bridge are relatively high due to the high support structure. The erection of cranes also faces the problem that large-tonnage equipment cannot enter the construction site. Using precast beams also presents the problem of difficulty in prefabrication and erection by bridge erecting machines.

[0003] To address the problem that existing bridge erecting machines often experience overturning during the erection of bridge slabs on small-radius, steep-slope curves, where the rear guide beam of the machine is suspended and lacks sufficient traction when crossing spans, Chinese invention patent application CN112323649A discloses a bridge erecting machine and a bridge construction method. The bridge erecting machine includes: a guide beam mechanism; a first leg mechanism connected to the end of the guide beam mechanism used for crossing spans; a second leg mechanism connected to the rear end of the guide beam mechanism; and a third leg mechanism slidably connected to the guide beam mechanism. The third leg mechanism is positioned between the first and second leg mechanisms. Both the first and third leg mechanisms are rotatably mounted to the guide beam mechanism, allowing the guide beam mechanism to rotate relative to the bridge. During bridge construction, when crossing a span, the guide beam mechanism is moved longitudinally to place the first leg mechanism onto the cap beam of the bridge to be erected. During this process, the guide beam mechanism can rotate relative to the third leg mechanism according to the curvature of the bridge. The tail end of the guide beam mechanism also moves towards the already erected beam, allowing the second leg mechanism located at the tail end of the guide beam mechanism to be supported on the already erected beam. Simultaneously, the first leg mechanism rotates relative to the guide beam mechanism, making its transverse axis parallel to the axis of the cap beam of the bridge to be erected, thus enabling the first leg mechanism to be supported on the cap beam. Therefore, the bridge erecting machine provided in this application can stably support the tail end of the guide beam mechanism while ensuring the first leg mechanism is stably supported on the cap beam of the bridge to be erected, preventing it from being suspended and thus avoiding the problem of the bridge erecting machine overturning.

[0004] The aforementioned patent application requires improvements to the bridge erecting machine, specifically a machine where both the first and third outrigger mechanisms are rotatably mounted to the guide beam mechanism. However, to ensure stable support of the guide beam by the outriggers, most bridge erecting machines currently on the market and used by construction companies typically employ bolted connections between the guide beam and outriggers. Therefore, adopting the bridge construction method described in the patent application necessitates purchasing or modifying a new bridge erecting machine, leading to increased costs. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems mentioned in the background art above, and provides a construction method for erecting small-radius precast bridge beams in mountainous areas. It is applicable to the erection of small-radius bridge precast beams with large cross slopes on secondary and tertiary highways or interchange ramps of high-grade highways in mountainous and hilly areas. It is suitable for the erection of bridge precast beams where the bridgehead space is limited and the operation of the bridge erecting machine is difficult. Moreover, the construction method can be carried out using existing bridge erecting machines on the market, without the need to purchase or modify a new bridge erecting machine.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A construction method for erecting precast bridge beams with small radius in mountainous areas includes the following steps:

[0008] Bridge erecting machine assembly: The bridge erecting machine includes two guide beams, a front support leg assembly, a middle support leg assembly, a rear support roller assembly, a rear support leg assembly, and a trolley. The two guide beams are arranged in parallel and spaced apart, and each guide beam is connected to a guide beam longitudinal movement motor. The front support leg assembly, the middle support leg assembly, the rear support roller assembly, and the rear support leg assembly are sequentially installed at the bottom of the two guide beams along the length direction of the guide beams. The guide beams are assembled from several segments, and the trolley is slidably mounted on the two guide beams.

[0009] First, assemble the guide beam of a preset length at the bridgehead. Then, connect the front support leg assembly, the middle support leg assembly, the rear support roller assembly, and the overhead crane to the assembled section of the guide beam. Move the overhead crane to the rear of the assembled section of the guide beam. Move the assembled bridge erecting machine forward a preset distance towards the first span. Then, assemble the remaining length of the guide beam and the rear support leg assembly. Finally, install a counterweight at the tail of the guide beam to complete the assembly of the bridge erecting machine.

[0010] Widening the cap beam: Before the bridge erecting machine passes through the span, the machine position is simulated on the bridge plan using drafting software to confirm whether the maximum rotation angle α of the bridge erecting machine is greater than the angle β between the minor axis of the cap beam of each pier and the axis of the guide beam. If not, the width of the cap beam along the longitudinal direction of the bridge needs to be widened to meet the construction requirements. In addition, it is also necessary to confirm whether the width of the cap beam in the transverse direction of the bridge can meet the erection of the outer beam. If not, the width of the cap beam along the transverse direction of the bridge needs to be widened to meet the construction requirements, ensuring that the front support leg assembly can fall within the cap beam range after the bridge erecting machine passes through the span, and avoiding the front support leg assembly being suspended in the air.

[0011] Bridge erecting machine crossing the span: The first span crossing is carried out directly after the bridge erecting machine is assembled, and the beam transport vehicle feeds and erects the beams normally. From the second span onwards, the bridge erecting machine needs to be adjusted in advance to cross the span, which includes the following steps:

[0012] When erecting the next precast beam after completing the erection of the previous span of the precast beam, the rear support leg assembly is supported on the precast beam that has been erected. Then, a counterweight is added to the tail of the guide beam and the rear support leg assembly is lifted.

[0013] The bridge erecting machine is supported by the front outrigger assembly and the rear support roller assembly, and then the middle outrigger assembly is lifted, moved forward and supported on the cap beam closest to the bridge abutment.

[0014] The bridge erecting machine is supported by the middle support leg assembly and the rear support roller assembly. The overhead crane is moved between the middle support leg assembly and the rear support roller assembly. The front support leg assembly is lifted, and the guide beam longitudinal movement motor is started to move the two guide beams forward synchronously, so that the front support leg assembly moves toward the cap beam of the beam to be erected.

[0015] When the front support leg assembly moves to a preset distance from the cap beam of the beam to be erected, the synchronous forward movement of the guide beam stops, the connecting bolts between the guide beam and the middle support leg assembly are loosened, and the differential speed of the two guide beams is controlled to advance until the lateral axis of the front support leg assembly is adjusted to be parallel to the long axis of the cap beam of the beam to be erected along the transverse direction of the bridge.

[0016] After adjusting the lateral axis of the front support leg assembly to be parallel to the long axis of the cap beam of the beam to be erected, tighten the connecting bolts between the guide beam and the middle support leg assembly, and continue to move the two guide beams forward synchronously until the front support leg assembly reaches and supports the cap beam of the beam to be erected, thus completing the passage through the hole; after the passage through the hole is completed, place the rear support leg assembly on the precast beam that has been erected, and remove the counterweight hanging at the tail of the guide beam;

[0017] Bridge deck beam transport and erection: The precast beam to be erected is transported from the tail end of the guide beam to the direction close to the front support leg assembly by the overhead crane, and the precast beam to be erected is lowered onto the cap beam of the beam to be erected for erection.

[0018] Furthermore, during the bridge deck beam transportation process, if the feeding angle of the bridge erecting machine's guide beam tail is too small when erecting the bridge span, causing the overhead crane to be unable to enter the bridge erecting machine and complete the beam feeding, then the last segment of the guide beam tail is removed to increase the feeding angle.

[0019] Furthermore, the removal of the final segment of the guide beam includes the following steps: After unloading the counterweights from the bridge erecting machine after passing through the arch, the overhead crane is moved forward to between the front support leg assembly and the middle support leg assembly. The rear support wheel assembly is supported on the erected precast beam. The rear support leg assembly is lifted, and the truck crane is positioned on the bridge. First, the transverse connection between the two guide beams is removed. Then, the final segment of the guide beam to be removed is hoisted using wire ropes and shackles and lifted by the truck crane. The wire ropes tighten the final segment of the guide beam, and then the bolt connection between the final segment and the front guide beam segment is loosened to separate the guide beam. The final segment of the guide beam is placed on a flatbed truck and transported away from the bridge deck using the truck crane. Finally, the transverse connection between the two guide beams is reinstalled, completing the removal of the final segment of the guide beam.

[0020] Furthermore, the location diagram of the bridge erecting machine was drawn on the software to simulate and determine whether the feeding angle of the bridge erecting machine's guide beam tail was too small during the span erection.

[0021] Furthermore, the precast beam includes an inner side beam, a middle beam, and an outer side beam, and the erection steps for the inner side beam, the middle beam, and the outer side beam are as follows:

[0022] The erection steps for the inner side beams and the middle beams include:

[0023] The bridge erecting machine is moved laterally to the inner side of the bridge. After the precast beam is transported into the machine position by the overhead crane, the overhead crane lifts the beam and moves the precast beam longitudinally along the bridge to the top of the span to be erected. Then, the bridge erecting machine is slowly moved laterally along the bridge to accurately move the guide beam to the top of the beam position. Temporary supports for the precast beam are installed, and after the elevation is determined to be correct, the steel wire rope is gradually lowered by the overhead crane to place the precast beam to be installed in place.

[0024] The first precast beam to be placed is the inner edge beam. After it is in place, the steel wire rope is not loosened. The inner edge beam is temporarily supported and secured before the steel wire rope is loosened to complete the erection of the inner edge beam. Then the middle beam is erected, and the transverse diaphragms and wet joint reinforcement between each precast beam are welded.

[0025] The steps for erecting the outer beams include:

[0026] The bridge erecting machine is moved laterally to the inner side of the bridge. After the overhead crane completes the lifting and longitudinal movement of the beam, the bridge erecting machine is slowly moved laterally to the top of the outer beam. Temporary supports for the outer beam are installed, and after the elevation is confirmed to be correct, the overhead crane gradually lowers the steel wire rope to place the outer beam into position.

[0027] Furthermore, after the outer beam is in place, it is temporarily supported. After the adjacent precast beams are erected, the reinforcing bars of the wet joint of the diaphragm between the adjacent precast beams are welded in a timely manner before the temporary support of the outer beam can be removed.

[0028] Furthermore, an 8t coiled steel bar counterweight is added to the tail of the guide beam using a chain hoist as an additional counterweight.

[0029] Furthermore, during the process of moving the middle support leg assembly forward and supporting it on the cap beam closest to the bridge abutment, sleepers are placed between the middle support leg assembly and the cap beam closest to the bridge abutment to ensure that the top surface of the middle support leg assembly is level at all points.

[0030] Furthermore, the angle between the short axis of the cap beam to be erected and the axis of the guide beam is β. The maximum rotation angle α of the bridge erecting machine is adjusted. When the maximum rotation angle α of the bridge erecting machine is consistent with the angle β, the transverse axis of the front support leg assembly is adjusted to be parallel to the transverse axis of the front cap beam.

[0031] Furthermore, the guide beam is 44 meters long. The first 30 meters of the guide beam are assembled at the bridgehead. The assembled bridge erecting machine is then moved 15 meters forward to the first span. The remaining 14 meters of the guide beam and the rear support leg assembly are then assembled.

[0032] By adopting the above technical solution, the present invention has the following beneficial effects:

[0033] 1. The construction method for erecting small-radius precast bridge beams in mountainous areas described above utilizes existing bridge erecting machines. In existing bridge erecting machines, the guide beam and middle support leg assembly are typically connected by bolts. Each guide beam is controlled by an independent longitudinal movement motor. During construction, the connecting bolts between the guide beam and the middle support leg assembly can be slightly loosened. By controlling the differential speed of the two guide beams through the longitudinal movement motors, a small angle can be formed between the guide beam and the middle support leg assembly. This allows adjustment of the bridge erecting machine's maximum rotation angle α, aligning the front support leg assembly parallel to the cap beam of the beam to be erected. This provides stable support to the tail end of the guide beam, preventing it from being suspended and thus avoiding the bridge erecting machine from overturning. This method is suitable for erecting small-radius, high-slope precast bridge beams on secondary or tertiary highways or interchange ramps of high-grade highways in mountainous and hilly areas. It is also suitable for bridge precast beam erection where the bridgehead space is limited and the assembly of the bridge erecting machine is difficult. Furthermore, this construction method can utilize existing bridge erecting machines on the market, eliminating the need to purchase or modify new machines.

[0034] 2. By installing counterweights at the tail of the guide beam, the total length of the bridge erecting machine is reduced, ensuring that the safety factor of the bridge erecting machine across the span meets the requirements, while also ensuring that the beam transport vehicle has a sufficient angle to feed the beam.

[0035] 3. The software simulates the layout of the bridge erecting machine position to determine whether the width of the cap beam meets the requirements for the side beam erection. Cap beams that do not meet the requirements are widened to ensure the front support leg assembly can stably support the cap beam, preventing the bridge erecting machine from overturning during the lateral movement of the front support leg when erecting the side beam. If the cap beam is not widened in advance, the bridge erecting machine may not be able to move laterally to the position of the outer side beam for the erection of precast beams of small-radius bridges. In existing technologies, a sliding track and jacking device are usually installed on the top surface of the cap beam to position the outer side beam in the adjacent beam slab, and then the sliding track and jacking device are used to laterally move the outer side beam to its position, which is quite cumbersome. This invention simulates the layout of the bridge erecting machine position in the software to determine whether the width of the cap beam meets the requirements for the side beam erection, and widens cap beams that do not meet the requirements, avoiding the situation where the bridge erecting machine may not be able to move laterally to the position of the outer side beam, thus facilitating construction. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a bridge erecting machine according to a preferred embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the maximum rotation angle α of the bridge erecting machine.

[0038] Figure 3 A schematic diagram showing the angle β between the minor axis of the cap beam and the axis of the guide beam;

[0039] Figure 4 Schematic diagram of widening the cap beam;

[0040] Figure 5 This is a schematic diagram of the included angle at the tail of the bridge erecting machine;

[0041] Figure 6 This is a schematic diagram showing the erection of the outer edge beam before the cap beam is widened.

[0042] Figure 7 A schematic diagram of the outer edge beams being erected after the cap beam has been widened;

[0043] Explanation of main component symbols

[0044] 1. Guide beam; 2. Front outrigger assembly; 3. Middle outrigger assembly; 4. Rear support roller assembly; 5. Rear outrigger assembly; 6. Overhead crane; 7. Precast beams that have been erected; 8. Cap beam closest to the bridge abutment; 9. Cap beams to be erected; 10. Counterweights. Detailed Implementation

[0045] 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. 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.

[0046] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] Please also see Figures 1 to 5 A preferred embodiment of the present invention provides a construction method for erecting small-radius precast bridge beams in mountainous areas, comprising the following steps:

[0049] Bridge erecting machine assembly: In this embodiment, an existing bridge erecting machine structure is adopted. The bridge erecting machine includes two guide beams 1, a front support leg assembly 2, a middle support leg assembly 3, a rear support roller assembly 4, a rear support leg assembly 5, and a crane 6. The two guide beams 1 are arranged in parallel and spaced apart. Each guide beam 1 is connected to a guide beam longitudinal movement motor (not shown in the figure). The front support leg assembly 2, the middle support leg assembly 3, the rear support roller assembly 4, and the rear support leg assembly 5 are installed sequentially at the bottom of the two guide beams 1 along the length direction of the guide beams 1. The guide beams 1 are assembled by several segments (not shown). The crane 6 is slidably mounted on the two guide beams 1.

[0050] The structures of the front outrigger assembly 2, middle outrigger assembly 3, rear support roller assembly 4, and rear outrigger assembly 5 are all existing technologies. They consist of an anti-roller system, outrigger telescopic columns, and a lateral movement mechanism. The front and middle outrigger assemblies support the machine's weight and external loads during beam erection. During cross-span operations, they provide two movable fulcrums for the machine. The anti-roller system enables the outriggers to self-drive and move forward when passing through spans. During beam erection, the front and middle outrigger assemblies 2 and 3 are locked to the guide beam 1 by bolts and pressure plates. The rear outrigger assembly 5 and rear support roller assembly 4 are located at the tail end of the guide beam 1 and are connected to the lower tail plane of the guide beam 1 via pressure plate elements. The front outrigger assembly 2, middle outrigger assembly 3, rear support roller assembly 4, and rear outrigger assembly 5 are equipped with retractable column core sleeve structures. The height is adjusted by lifting the column core through a hydraulic cylinder. The extension and retraction of the front outrigger assembly 2, middle outrigger assembly 3, rear support roller assembly 4, and rear outrigger assembly 5 are adjusted by hydraulic cylinders. The operation of each mechanism of the bridge erecting machine is controlled by an electrical system, which is existing technology and will not be described in detail here.

[0051] When assembling the bridge erecting machine, first, the pre-set length of the guide beam 1 is assembled at the bridgehead. Then, the front support leg assembly 2, the middle support leg assembly 3, the rear support roller assembly 4, and the overhead crane 6 are connected to the assembled section of the guide beam 1. The overhead crane 6 is moved to the rear of the assembled section of the guide beam 1. The assembled bridge erecting machine is moved forward a pre-set distance, such as 15m, towards the first span. Then, the remaining length of the guide beam 1 and the rear support leg assembly 5 are assembled. Finally, the counterweight 10 is installed at the tail of the guide beam 1 to complete the assembly of the bridge erecting machine.

[0052] According to the current "Technical Specifications for Construction of Highway Bridges and Culverts," the length of the bridge erecting machine should meet the requirement that the stability safety factor when crossing the span is not less than 1.5, and the minimum length of the bridge erecting machine should be greater than the sum of the length of the precast beam and the length of the gantry crane feeding beam. In this embodiment, the length of the precast beam is 20 meters, and the length of the gantry crane feeding beam is 8 meters. Considering the weight of each component of the bridge erecting machine, the length of the bridge erecting machine should be at least 50 meters when crossing the span to meet the stability safety factor requirement. Therefore, in this embodiment, the total length of the bridge erecting machine should not be less than 50 meters. Due to the limitations of the terrain conditions at the bridgehead, the total length of this bridge erecting machine is too long, making it difficult to assemble and cross the span on small-radius horizontal curves. In this embodiment, by hanging counterweights 10 at the rear end of the guide beam 1, specifically, two sets of coiled steel bars can be hung at the end of each of the two guide beams 1 as counterweights 10, with a total counterweight of 8t, the total length of the bridge erecting machine is reduced to 44 meters. That is, the guide beam includes two 12m segments + one 6m segment + one 14m segment. The segments are spliced ​​together by bolts, which makes it easier to pass through holes on small radius plane curves and also meets the specifications.

[0053] In some construction scenarios, due to limitations in the terrain at the bridgehead, the bridge erecting machine can only be assembled up to 30m in length, making it impossible to assemble the machine in one go. To solve this problem, the pre-set length of the guide beam 1 can be assembled first at the bridgehead. In this embodiment, the first 30m of the guide beam 1 segment is assembled first at the bridgehead; then the front support leg assembly 2, the middle support leg assembly 3, the rear support roller assembly 4, and the overhead crane 6 are connected to the assembled segment of the guide beam 1. The overhead crane 6 is moved to the rear of the assembled segment of the guide beam 1, and the assembled bridge erecting machine is moved forward 15m towards the first span. Finally, the remaining 14m of the guide beam 1 and the rear support leg assembly 5 are assembled.

[0054] Widening the cap beam: Before the bridge erecting machine passes through the span, the machine position is simulated on the bridge plan using CAD or other drafting software. It is confirmed whether the maximum rotation angle α of the bridge erecting machine is greater than the angle β between the short axis of the cap beam of each pier and the axis of the guide beam. If not, the width of the cap beam along the longitudinal direction of the bridge needs to be widened to meet the construction requirements. In addition, it is also confirmed whether the width of the cap beam in the transverse direction of the bridge can meet the erection of the side beam. If not, the width of the cap beam along the transverse direction of the bridge needs to be widened to meet the construction requirements, ensuring that the front support leg assembly 2 can fall within the cap beam range after the bridge erecting machine passes through the span, and avoiding the front support leg assembly 2 being suspended in the air.

[0055] When the maximum rotation angle α of the bridge erecting machine is less than the angle β between the minor axis of the cap beam of each pier and the axis of the guide beam, it indicates that the transverse track of the front support leg assembly 2 is suspended in the longitudinal direction of the cap beam. In this case, the width of the cap beam in the longitudinal direction needs to be widened. The widening width should ensure that the transverse track of the front support leg assembly 2 always falls within the cap beam range in the longitudinal direction. If α is greater than β, the transverse track of the front support leg assembly 2 will not exceed the cap beam and be suspended. The size of the transversely widened cap beam is independent of the values ​​of α and β. Whenever there is a possibility that the front support leg assembly 2 will be suspended during the erection of the outer beam in the software simulation, the cap beam needs to be widened in the transverse direction.

[0056] Please refer to the table below. In this embodiment, the small radius bridge includes pier #1, pier #2, pier #3, pier #4 and abutment #5. Abutment #5 is a bridge abutment, and the roadbed is behind it. The included angle between them does not affect the beam erection. The cap beams on each of piers #1, #2, #3, and #4 all satisfy α>β. Therefore, the cap beams on each pier do not need to be widened along the longitudinal direction of the bridge.

[0057]

[0058] Due to the small turning radius, except for the cap beam of pier #1 located on the transition curve, the cap beams of piers #2 to #4 all need to be widened in the transverse direction. In this embodiment, the width of the widening is 1.5m. In other embodiments, the width of the widening can be adjusted as needed, as long as the front support leg assembly 2 is not suspended in the air.

[0059] Bridge erecting machine crossing the span: The first span crossing is carried out directly after the bridge erecting machine is assembled, and the beam transport vehicle feeds and erects the beams normally; from the second span onwards, the bridge erecting machine needs to be adjusted in advance to cross the span, which includes the following steps:

[0060] S1, after the erection of the previous span of precast beam is completed, when erecting the next span of precast beam, the rear support leg assembly 5 is supported on the already erected precast beam. Then, a counterweight 10 is added to the tail of the guide beam 1, and the rear support leg assembly 5 is lifted. In this embodiment, in step S1, an 8t coiled steel bar counterweight is added to the tail of the guide beam 1 using a chain hoist as the added counterweight 10; the hydraulic cylinder on the rear support leg assembly 5 is adjusted to allow the rear support leg assembly 5 to be lowered or lifted.

[0061] S2, the bridge erecting machine is supported by the front outrigger assembly 2 and the rear support roller assembly 4, and then the middle outrigger assembly 3 is lifted, moving the middle outrigger assembly 3 forward and supporting it on the cap beam closest to the bridge abutment. In this embodiment, the middle outrigger assembly 3 is lowered or raised by adjusting the hydraulic cylinder on the middle outrigger assembly 3, and the rear support roller assembly 4 is lowered or raised by adjusting the hydraulic cylinder on the rear support roller assembly 4.

[0062] In step S3, the bridge erecting machine is supported by the middle support leg assembly 3 and the rear support roller assembly 4. The overhead crane 6 is moved between the middle support leg assembly 3 and the rear support roller assembly 4, the front support leg assembly 2 is lifted, and the guide beam longitudinal movement motor is started to move the two guide beams 1 forward synchronously, so that the front support leg assembly 2 moves towards the cap beam of the beam to be erected. In this embodiment, in step S3, the two guide beam longitudinal movement motors drive the two guide beams 1 to move synchronously towards the cap beam of the beam to be erected at the same speed; the hydraulic cylinders on the front support leg assembly 2 are adjusted to make the front support leg assembly 2 land or be lifted. In step S3, the overhead crane 6 can be moved as close as possible to the rear support roller assembly 4, so that the center of gravity of the bridge erecting machine is moved rearward, improving the anti-overturning safety factor when crossing the span.

[0063] S4, when the current outrigger assembly 2 moves to a preset distance from the cap beam of the beam to be erected, stop the synchronous forward movement of the guide beam 1, loosen the connecting bolts between the guide beam 1 and the middle outrigger assembly 3, and control the differential speed of the two guide beams 1 to advance until the transverse axis of the front outrigger assembly 2 is adjusted to be parallel to the long axis of the cap beam of the beam to be erected along the transverse direction of the bridge, and the long axis of the cap beam along the transverse direction of the bridge is perpendicular to the short axis of the cap beam.

[0064] In this embodiment, in step S4, the two guide beam longitudinal movement motors drive the two guide beams 1 to move in the same direction at different speeds, thereby achieving differential speed forward movement. When adjusting the transverse axis of the front support leg assembly 2, based on the angle β between the minor axis of the cap beam of the beam to be erected and the axis of the guide beam, the connecting bolts between the guide beam 1 and the middle support leg assembly 2 are slightly loosened. By controlling the differential speed forward movement of the left and right guide beams 1, the maximum rotation angle α of the bridge erecting machine is adjusted. When the maximum rotation angle α of the bridge erecting machine is consistent with or close to the angle β, it indicates that the transverse axis of the front support leg assembly 2 has been adjusted to be parallel to the major axis of the cap beam of the beam to be erected along the transverse direction. Furthermore, during the adjustment of the maximum rotation angle α of the bridge erecting machine, the angle adjustment must be slow, following the principle of "small steps multiple times," gradually adjusting the front support leg assembly 2 to be parallel to the axis of the cap beam of the beam to be erected along the transverse direction.

[0065] S5. After adjusting the transverse axis of the front outrigger assembly 2 to be parallel to the longitudinal axis of the cap beam of the beam to be erected along the transverse direction, tighten the connecting bolts between the guide beam 1 and the middle outrigger assembly 3, and continue to move the two guide beams 1 forward synchronously until the front outrigger assembly 2 reaches and supports the cap beam of the beam to be erected, thus completing the passage through the hole. After the passage through the hole is completed, place the rear outrigger assembly 5 on the precast beam that has been erected, and remove the counterweight 10 hanging at the tail of the guide beam.

[0066] Furthermore, during the process of moving the middle support leg assembly 3 forward and supporting it on the cap beam closest to the bridge abutment, sleepers can be placed between the middle support leg assembly 3 and the cap beam closest to the bridge abutment to ensure that the top surface of the middle support leg assembly 3 is level. During the process of moving the front support leg assembly 2 forward and supporting it on the cap beam of the beam to be erected, sleepers can be used to level the top surface of the cap beam of the beam to be erected. After checking the levelness of the top surface with a spirit level, the front support leg assembly 2 is then placed on the cap beam.

[0067] S6, Bridge deck beam transport and erection: The precast beam to be erected is transported from the tail end of the guide beam 1 to the direction close to the front support leg assembly 2 by the overhead crane 6, and the precast beam to be erected is lowered onto the cap beam of the beam to be erected for erection.

[0068] Before transporting the beams, the welding of wet joints between beams and slabs and the continuous end reinforcement at the pier top must be completed in a timely manner. To ensure the stability of the bridge erecting machine and the overhead crane 6 during travel, all the main reinforcement bars of the transverse diaphragms between adjacent beams and slabs should be welded, and at least 1 / 3 of the reinforcement bars at the wet joints should be welded. At the same time, at the location where the beam transport vehicle crosses the joint, all the reinforcement bars at the wet joint should also be welded. Small-radius bridges generally have a large cross slope, so the bridge deck should be leveled with steel plates, sleepers, and other materials along the beam transport vehicle's travel path to facilitate the movement of the overhead crane 6.

[0069] In step S6, a bridge erecting machine positioning diagram drawn using CAD or other drafting software can be used to simulate and determine whether the feeding angle at the tail of the bridge erecting machine's guide beam is too small during span erection. Please refer to [link to relevant documentation]. Figure 5As shown in the bridge erecting machine station diagram drawn on the CAD drawing software, when erecting the 3rd and 4th spans, the feeding angle of the bridge erecting machine's guide beam tail is too small, and the beam transport vehicle cannot enter. During the beam transport process on the bridge deck, if the feeding angle of the bridge erecting machine's guide beam tail is too small when erecting the span, causing the overhead crane 6 to be unable to enter the bridge erecting machine and complete the beam feeding, the last segment of the guide beam 1 is removed to increase the feeding angle. The removal of the last segment of the guide beam 1 includes the following steps: After unloading the counterweight 10 from the bridge erecting machine after passing through the hole, move the overhead crane 6 forward to between the front support leg assembly 2 and the middle support leg assembly 3, support the rear support roller assembly 4 on the erected precast beam, lift the rear support leg assembly 5, and position the truck crane on the bridge. First, remove the transverse connection between the two guide beams 1, then use wire ropes and shackles to suspend the last segment of the guide beam 1 to be removed and lift it up using the truck crane. The wire rope tightens the last segment of the guide beam 1 under stress. Then, loosen the bolt connection between the last segment and the front guide beam segment, separate the guide beam 1, and use the truck crane to place the last segment of the guide beam 1 onto a flatbed truck to be transported away from the bridge deck. Then, reinstall the transverse connection between the two guide beams 1 to complete the removal of the last segment of the guide beam 1.

[0070] In step S6, the precast beam includes an inner side beam, a middle beam, and an outer side beam. The erection steps for the inner side beam, the middle beam, and the outer side beam are as follows:

[0071] The erection steps for the inner side beams and the middle beams include:

[0072] The bridge erecting machine is moved laterally to the inner side of the bridge. After the precast beam is transported into the machine position by the overhead crane 6, the overhead crane 6 lifts the beam and moves the precast beam longitudinally along the bridge to the top of the span to be erected. Then, the bridge erecting machine is slowly moved laterally along the bridge to accurately move the guide beam 1 to the top of the beam position. Temporary supports for the precast beam are installed, and after the elevation is determined to be correct, the steel wire rope is gradually lowered by the overhead crane 6 to place the precast beam to be installed in place.

[0073] The first precast beam to be placed is the inner edge beam. After it is in place, the steel wire rope is not loosened. The inner edge beam is temporarily supported and secured before the steel wire rope is loosened to complete the erection of the inner edge beam. Then the middle beam is erected, and the transverse diaphragms and wet joint reinforcement between each precast beam are welded.

[0074] The steps for erecting the outer beams include:

[0075] The bridge erecting machine is moved laterally to the inner side of the bridge. After the overhead crane 6 completes the lifting and longitudinal movement of the beam, the bridge erecting machine is slowly moved laterally to above the outer beam. Temporary supports for the outer beam are installed, and after confirming the elevation is correct, the overhead crane 6 gradually lowers the wire rope to position the outer beam. After the outer beam is in place, it is temporarily supported. Once the adjacent precast beams are erected, the wet joint reinforcement of the transverse diaphragms between the adjacent precast beams is welded in a timely manner before the temporary supports for the outer beam can be removed.

[0076] The construction method for erecting small-radius precast bridge beams in the aforementioned mountainous areas uses existing bridge erecting machines. In existing bridge erecting machines, the guide beam 1 and the middle support leg assembly 3 are usually connected by bolts. The two guide beams 1 are controlled by independent guide beam longitudinal movement motors. During construction, the connecting bolts between the guide beam 1 and the middle support leg assembly 3 can be slightly loosened. By controlling the differential speed of the two guide beams 1 through the guide beam longitudinal movement motors, a small angle can be formed between the guide beam 1 and the middle support leg assembly 3. This allows the maximum rotation angle α of the bridge erecting machine to be adjusted so that the front support leg assembly 2 is parallel to the cap beam of the beam to be erected, ensuring stable support for the tail end of the guide beam 1 and preventing it from being suspended in mid-air, thereby preventing the bridge erecting machine from overturning.

[0077] By installing a counterweight 10 at the tail of the guide beam, the total length of the bridge erecting machine is reduced, ensuring that the safety factor of the bridge erecting machine across the span meets the requirements, while also ensuring that the beam transport vehicle has a sufficient angle to feed the beam.

[0078] The software simulates the placement of the bridge erecting machine, determining whether the width of the cap beam meets the requirements for side beam erection. Cap beams that do not meet the requirements are widened to ensure that the front support leg assembly 2 can stably support the cap beam, preventing it from being suspended and thus preventing the bridge erecting machine from overturning during the lateral movement of the front support leg when erecting the side beam. If the cap beam is not widened in advance, for the erection of precast beams of small-radius bridges, the bridge erecting machine may not be able to move laterally to the beam position of the outer side beam. Figure 6 This diagram illustrates the erection of the outer side beams before the cap beam is widened. As can be seen, with the original cap beam width, the lateral movement track of the outer guide beam 1 and the front support leg assembly 2 of the bridge erecting machine will be suspended in mid-air during the erection of the outer side beams. In existing technology, a sliding track and a jacking device are typically installed on the top surface of the cap beam. After the outer side beam is positioned at the adjacent beam, the sliding track and jacking device laterally move the outer side beam to its designated position. However, this method is time-consuming, requires complex equipment, and necessitates the installation of a set of equipment on each pier top, making it quite cumbersome. This invention simulates the layout of the bridge erecting machine position in software, determines whether the cap beam width meets the requirements for side beam erection, and widens cap beams that do not meet the requirements. This avoids situations where the bridge erecting machine may be unable to laterally move to the outer side beam position, making construction more convenient. Figure 7 As shown. Furthermore, for the erection of precast beams for small-radius bridges, a relatively long section of the transverse guide rail on the front outrigger assembly 2 of the bridge erecting machine may be suspended above the cap beam of the beam to be erected. When the front outrigger of the front outrigger assembly moves along its transverse guide rail, it can easily cause the bridge erecting machine to tip over. In the prior art, Usually adopted Used to attach counterweights to one side of the bridge erecting machine to balance it.However, the risk of instability of the bridge erecting machine still exists, indicating insufficient reliability. This embodiment uses software to simulate the situation where the front outrigger assembly is supported on the cap beam of the beam to be erected. When a long section of the transverse guide rail on the front outrigger assembly of the bridge erecting machine may be suspended on the cap beam of the beam to be erected, the cap beam is widened along the transverse direction of the bridge to ensure that the transverse guide rail on the front outrigger assembly always falls within the range of the cap beam of the beam to be erected, greatly reducing the risk of the bridge erecting machine overturning and reducing subsequent investment.

[0079] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A construction method for erecting a precast beam of a small-radius bridge in a mountainous area, characterized in that, The method comprises the following steps: The bridge erecting machine is assembled: the bridge erecting machine comprises two guide beams, a front support leg assembly, a middle support leg assembly, a rear supporting wheel assembly, a rear support leg assembly and a trolley, the two guide beams are arranged in parallel and at intervals, and each guide beam is connected with a guide beam longitudinal movement motor; the front support leg assembly, the middle support leg assembly, the rear supporting wheel assembly and the rear support leg assembly are sequentially arranged on the bottom of the two guide beams along the length direction of the guide beams, the guide beams are assembled by a plurality of segments, and the trolley is slidably arranged on the two guide beams; The assembly of the guide beams of a preset length is first completed at the bridge head, then the front support leg assembly, the middle support leg assembly, the rear supporting wheel assembly and the trolley are connected with the assembled segments of the guide beams, the trolley is moved to the rear of the assembled segments of the guide beams, the assembled bridge erecting machine is moved forward by a preset distance in front of the first span, the assembly of the guide beams of the remaining length and the rear support leg assembly is completed, then counterweights are arranged at the tail of the guide beams, and the assembly of the bridge erecting machine is completed; The width of the bent cap is widened: before the bridge erecting machine passes through the hole, the position of the bridge erecting machine is simulated and arranged on the bridge type plane by using drawing software, whether the maximum turning angle α of the bridge erecting machine is greater than the included angle β between the short axis of the bent cap of each pier of the bridge and the axis of the guide beam is determined, if not, the width of the bent cap in the longitudinal direction of the bridge needs to be widened to meet the construction requirements; in addition, whether the width of the bent cap in the transverse direction of the bridge can meet the erection of the outer beam is also determined, if not, the width of the bent cap in the transverse direction of the bridge is widened to meet the construction requirements, so that the front support leg assembly can be arranged in the range of the bent cap after the bridge erecting machine passes through the hole, and the front support leg assembly is prevented from being suspended in the air; The bridge erecting machine passes through the hole: the first span passes through the hole directly after the assembly of the bridge erecting machine is completed, the beam transport vehicle normally feeds and erects the beam, and from the second span, the posture of the whole machine needs to be adjusted in advance before the bridge erecting machine passes through the hole, and the specific steps include the following steps: When the erection of the precast beam of the previous span is completed, the erection of the precast beam of the next span is carried out, the rear support leg assembly is supported on the precast beam which has been erected, then counterweights are hung at the tail of the guide beam, and the rear support leg assembly is lifted; The bridge erecting machine is supported by the front support leg assembly and the rear supporting wheel assembly, then the middle support leg assembly is lifted, the middle support leg assembly is moved forward and supported on the bent cap closest to the bridge head; The bridge erecting machine is supported by the middle support leg assembly and the rear supporting wheel assembly, the trolley is moved to the middle support leg assembly and the rear supporting wheel assembly, the front support leg assembly is lifted, the guide beam longitudinal movement motor is started, the two guide beams are synchronously moved forward, so that the front support leg assembly moves towards the bent cap of the beam to be erected; When the front support leg assembly moves to a preset distance from the bent cap of the beam to be erected, the synchronous forward movement of the guide beams is stopped, the connecting bolts between the guide beams and the middle support leg assembly are loosened, the differential forward movement of the two guide beams is controlled, and the transverse axis of the front support leg assembly is adjusted to be parallel to the long axis of the bent cap of the beam to be erected in the transverse direction of the bridge. After the transverse axis of the front leg assembly is adjusted to be parallel to the long axis of the bent cap to be erected, the connecting bolts between the guide beam and the middle leg assembly are tightened again, and the two guide beams are continuously moved forward synchronously until the front leg assembly reaches and supports above the bent cap to be erected, and the hole is completed; after the hole is completed, the rear leg assembly is lowered on the precast beam that has been erected, and the counterweight arranged at the tail of the guide beam is removed; Bridge deck beam transportation and beam lifting erection: the precast beam to be erected is transported by the overhead crane from the tail end of the guide beam to the direction close to the front leg assembly, and is lowered on the bent cap to be erected for erection.

2. The construction method for erecting a precast beam of a small-radius bridge in a mountainous region according to claim 1, wherein During the bridge deck beam transportation, if the feeding beam angle of the tail of the guide beam is too small when the hole is crossed, the overhead crane cannot enter the bridge girder erection machine, and the feeding beam cannot be completed, then the last segment of the tail of the guide beam is removed to increase the feeding beam angle.

3. The method of claim 2, wherein the method further comprises: The removal of the last segment of the tail of the guide beam includes the following steps: after the counterweight on the bridge girder erection machine is removed after the hole is crossed, the overhead crane is moved forward between the front leg assembly and the middle leg assembly, the rear roller assembly is supported on the precast beam that has been erected, the rear leg assembly is lifted, the automobile crane is positioned on the bridge, the transverse connection between the two guide beams is first removed, then the last segment of the guide beam to be removed is lifted by the automobile crane using the steel wire rope and the clasp ring, the steel wire rope is tightened to bear the force of the last segment of the guide beam, then the bolt connection between the last segment and the front segment of the guide beam is loosened, the guide beam is separated, the last segment of the guide beam is placed on the flat car and transported away from the bridge deck by the automobile crane, then the transverse connection between the two guide beams is reinstalled, and the removal of the last segment of the guide beam is completed.

4. The method of claim 2, wherein the method further comprises the steps of: providing a plurality of precast beams; and placing the plurality of precast beams on the plurality of support structures. The bridge girder erection machine station diagram drawn on the software is used to simulate and determine whether the feeding beam angle of the tail of the guide beam is too small when the hole is crossed.

5. The method of claim 1, wherein the method further comprises: providing a plurality of precast beams; and placing the plurality of precast beams on the plurality of support structures. The precast beam includes inner edge beams, middle beams and outer edge beams, and the erection steps of the inner edge beams, the middle beams and the outer edge beams are as follows: The erection steps of the inner edge beams and the middle beams include: The bridge girder erection machine is moved horizontally to the inner side of the bridge, the precast beam is transported into the machine position by the overhead crane, the overhead crane lifts the beam and moves the precast beam longitudinally along the bridge to above the bridge span to be erected, then the bridge girder erection machine is slowly moved horizontally, the guide beam is accurately moved to above the beam position, the temporary support of the precast beam is installed, and after the height is determined to be correct, the overhead crane gradually lowers the steel wire rope to position the precast beam to be installed; The first precast beam positioned is the inner edge beam, the steel wire rope is not loosened after the inner edge beam is positioned, the inner edge beam is firmly supported temporarily, then the steel wire rope is loosened to complete the erection of the inner edge beam, then the middle beam is erected, and the transverse diaphragm and the wet joint steel bars between the precast beams are welded. The erection steps of the outer edge beam include: The bridge girder erection machine is moved horizontally to the inner side of the bridge, the overhead crane completes the lifting and longitudinal movement, and then the bridge girder erection machine is slowly moved horizontally to above the outer edge beam, the temporary support of the outer edge beam is installed, and after the height is determined to be correct, the overhead crane gradually lowers the steel wire rope to position the beam plate of the outer edge beam.

6. The method of claim 5, wherein the method further comprises: After the outer edge beam is positioned, the outer edge beam is temporarily supported, after the adjacent precast beams are erected, the transverse diaphragm and the wet joint steel bars between the adjacent precast beams are welded in time, and then the temporary support of the outer edge beam can be removed.

7. The method of claim 1, wherein the method further comprises: providing a plurality of precast beams; and placing the plurality of precast beams on the plurality of support structures. The counterweight is hung by using a chain hoist to hang a 8t round steel counterweight at the tail of the guide beam.

8. The method of claim 1, wherein the method further comprises: providing a plurality of precast beams; and placing the plurality of precast beams on the plurality of support structures. During the process of moving forward and supporting the middle leg assembly to the nearest pier, the top surface of the middle leg assembly is ensured to be horizontal by supporting a cushion log between the middle leg assembly and the nearest pier.

9. The method of claim 1, wherein the method further comprises: providing a plurality of precast beams; and placing the plurality of precast beams on the plurality of piers to form the bridge. The angle between the short axis of the pier to be erected and the axis of the guide beam is β, the maximum turning angle α of the bridge girder erecting machine is adjusted, and when the maximum turning angle α of the bridge girder erecting machine is consistent with the angle β, the transverse axis of the front leg assembly is adjusted to be parallel to the axis of the front pier in the transverse direction of the bridge.

10. The method of claim 1, wherein the method further comprises: providing a plurality of precast beams; and placing the plurality of precast beams on the plurality of support structures. The length of the guide beam is 44m, the assembly of the front 30m of the guide beam is completed at the bridge head first, the assembled bridge girder erecting machine is moved forward by 15m to the first span, and the assembly of the remaining 14m of the guide beam and the rear leg assembly is completed.

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