Multi-span parallel double cantilever bridge erecting machine and method for erecting and crossing bridge

Abstract

The application discloses a double-cantilever bridge girder erection machine with multiple parallel bridges and a girder erection and hole crossing method, wherein a main truss is arranged along a construction direction, a front hoisting trolley and a rear hoisting trolley are arranged on the upper surface of the main truss, and the trolleys move back and forth along the construction direction on the tracks above the main girder; a trolley transverse moving mechanism is arranged on the upper portions of the front and rear hoisting trolleys to realize the transverse moving of the hoisted girder and complete the erection of multiple bridges simultaneously; four sets of supporting legs are arranged below the main truss, and the supporting legs are sequentially arranged from front to rear as a front auxiliary supporting leg, a front supporting leg, a middle supporting leg and a rear supporting leg, wherein the front auxiliary supporting leg is arranged at the most front end; the four sets of supporting legs can move back and forth along the construction direction; and a transverse moving mechanism is arranged on the upper portions of the front and middle supporting legs to realize the transverse moving of the parts above the main truss and complete the erection of multiple bridges simultaneously. The double-cantilever bridge girder erection machine adopts a two-end cantilever type girder erection mode, can erect multiple parallel bridges simultaneously while meeting the requirements of large-span girder erection and hole crossing, reduces the hole crossing bending moment and lightens the weight of the machine.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bridge construction equipment, in particular to a multi-span parallel double-cantilever bridge erecting machine and a method for erecting and passing through a hole. BACKGROUND

[0002] The bridge erecting machine is a device for placing a prefabricated beam on a prefabricated pier. The bridge erecting machine belongs to the category of cranes, because its main function is to lift the beam and then place it down after being transported to the position. However, the bridge erecting machine is quite different from the general crane. The bridge erecting machine has strict requirements and the beam moves longitudinally. The bridge erecting machine is divided into several types, such as erecting a highway bridge, a conventional railway bridge, and a passenger special railway bridge.

[0003] The bridge erecting machine generally includes an arm, a hoist trolley, a first column, a second column, and a third column.

[0004] The arm is a load-bearing girder of the bridge erecting machine, which is a double-box girder structure. According to the stress working condition and finite element analysis calculation of the arm, each box girder is designed to be a box-shaped variable cross-section form.

[0005] The bridge erecting machine is equipped with two hoist trolleys, each having independent lifting mechanisms, running mechanisms, and transverse moving mechanisms. Each hoist trolley is equipped with two independent lifting mechanisms. The two lifting mechanisms of the rear trolley are balanced through a balancing mechanism to balance the stress of the left and right lifting points, so that the four lifting points of the bridge erecting machine during the beam lifting operation are converted into three lifting points, so that the box girder is evenly loaded and smoothly lifted.

[0006] The first column is the front leg of the bridge erecting machine, which is supported on the front half of the support cushion stone in front of the pier. It is mainly composed of a supporting and hanging wheel mechanism, a folding column, and a telescopic column. During the beam erection operation, the first column is longitudinally fixed with the arm to form a hinged structure, becoming a flexible leg, and together with the arm and the second column, forming a gantry structure to meet the support requirements of the beam erection operation. During the longitudinal movement operation, the first column can move relative to the arm to realize the walking longitudinal movement of the bridge erecting machine. The first column is provided with a folding mechanism to meet the needs of the normal beam erection and the support of the last hole box girder erection on the abutment. The first column and the arm have three fixed positions to meet the erection of box girders with three different spans.

[0007] The second column is located in the middle of the arm and is fixed with the arm, which is a rigid leg. The lower crossbeam of the second column is provided with two legs, which can realize the support cushion and removal of supporting sleepers through a hydraulic cylinder, meeting the requirements of step changing during longitudinal movement and stable support during beam erection operation. The two legs are provided with a transverse moving mechanism, which drives the arm to swing through a transverse moving cylinder, so as to adjust the position of the bridge erecting machine horizontally to adapt to the curve beam erection requirement. Due to the need of the working condition of the beam carrying vehicle carrying the bridge erecting machine, the lower crossbeam is designed to be detachable.

[0008] Column No. 3 is the longitudinal drive support for the bridge erecting machine. To meet the requirements of beam feeding vehicle passage and longitudinal drive of the bridge erecting machine, it is designed as a gantry structure. It consists of a lifting column, folding mechanism, traveling mechanism, hydraulic suspension balancing device, steering mechanism, etc.

[0009] Bridge erecting machines are now widely used for erecting highway and railway bridges. Currently, when erecting simply supported beams, the bridge erecting machines used both domestically and internationally first move the beam-lifting trolley laterally to the middle position of the two truss beams. The front and rear beam-lifting trolleys then work together to lift the beam and move it longitudinally between the two bridge abutments. Finally, the bridge erecting machine and the beam-lifting trolley are moved laterally to the accurate position to lower the beam.

[0010] With rapid economic development, transportation tools have undergone tremendous changes, and highway and railway transportation systems have achieved significant sustainable development. In road transportation construction, the progress of bridge construction, especially large and extra-large bridges, has a major impact on the completion of the entire transportation route.

[0011] While existing bridge erecting machines can perform the work, they are heavy when erecting large-span beams, often have multiple beams placed side by side, and have large bending moments across the spans, which can easily lead to accidents. Summary of the Invention

[0012] This application provides a multi-span parallel double cantilever bridge erecting machine and its beam erection and span crossing method in several aspects. It adopts a cantilever beam erection at both ends, which can simultaneously erect multiple parallel bridges while meeting the requirements of large-span beam erection, and at the same time reduce the bending moment of span crossing and reduce the weight of the whole machine.

[0013] One aspect of this application provides a multi-section lateral double cantilever bridge erecting machine, the double cantilever bridge erecting machine comprising a main truss, a front crane, a rear crane, a front auxiliary outrigger, a front outrigger, a middle outrigger, and a rear outrigger, wherein...

[0014] Along the construction direction, the main truss is equipped with a front crane and a rear crane. The front crane and the rear crane can move back and forth along the construction direction along the main truss. The upper part of the front crane and the rear crane is equipped with a crane lateral movement mechanism to realize the lateral movement of the lifting beam to complete the simultaneous erection of multiple beams.

[0015] Below the main truss, the front auxiliary leg, the front support leg, the middle support leg, and the rear support leg are arranged in sequence, wherein the front auxiliary leg is located at the foremost end. The front auxiliary leg, the front support leg, the middle support leg, and the rear support leg can move back and forth along the construction direction. The front support leg and the middle support leg are equipped with a lateral movement mechanism to enable the lateral movement of the part above the main truss to complete the simultaneous erection of multiple sections.

[0016] Optionally, the bottom of the front outrigger is equipped with a telescopic sleeve, the upper part of the front outrigger supports the main truss, the upper part of the front outrigger is the roller support device, and the lower part is anchored to the pier.

[0017] Optionally, the upper part of the middle support leg is a roller device, and the lower part has eight jacking cylinders.

[0018] Optionally, the upper part of the rear support leg is rigidly connected to the main truss, and the lower part has a jacking cylinder.

[0019] Another aspect of the present application provides a method for erecting a bridge with a double cantilever bridge erecting machine, the double cantilever bridge erecting machine comprising a main truss, a front crane, a rear crane, a front auxiliary support leg, a front support leg, a middle support leg, and a rear support leg, wherein the main truss is arranged along a construction direction, the front crane and the rear crane are arranged on the upper part of the main truss, and the front crane and the rear crane are movable along the main truss in the construction direction, the front crane and the rear crane are provided with a crane transverse moving mechanism on the upper part to realize transverse moving of the hoisted beam and complete simultaneous erection of multiple spans; the front auxiliary support leg, the front support leg, the middle support leg, and the rear support leg are arranged in sequence on the lower part of the main truss, wherein the front auxiliary support leg is arranged at the foremost end, and the front auxiliary support leg, the front support leg, the middle support leg, and the rear support leg are movable along the construction direction; the front support leg and the middle support leg are provided with a transverse moving mechanism on the upper part to realize transverse moving of the part above the main truss and complete simultaneous erection of multiple spans.

[0020] The method for erecting a bridge with the double cantilever bridge erecting machine comprises the following steps:

[0021] The double cantilever bridge erecting machine is in a bridge erecting station state, a front beam carrier is positioned, a hoist of the front crane is connected to a front end lifting point of the steel beam, the front crane lifts the steel beam to make the steel beam front end disengage from the front beam carrier;

[0022] The front crane and a rear beam carrier move forward in linkage, a rear end lifting point of the steel beam is lowered to the rear crane and then stopped, a hoist of the rear crane is connected to the rear end lifting point of the steel beam, and the rear crane lifts the steel beam to make the steel beam rear end disengage from the rear beam carrier;

[0023] The front crane and the rear crane move longitudinally in linkage to a position, the front crane and the rear crane move transversely in linkage to a position, and the front crane and the rear crane move vertically in linkage to install the steel beam at a designated position;

[0024] The double cantilever bridge erecting machine is fixedly connected to a new steel beam in hanging and a certain pre-tightening force is applied, the front crane and the rear crane are used to install a precast bridge deck slab on the steel beam;

[0025] The connection between the steel beam and the hanging is released, and the bridge erecting machine is ready for hole passing.

[0026] Optionally, the bottom of the front leg is equipped with a telescopic sleeve, the upper part of the front leg is supported by a roller device, and the upper part of the front leg is a roller device and the lower part is anchored to the pier.

[0027] Optionally, the upper part of the middle leg is a roller device and the lower part is supported by eight jacking cylinders.

[0028] Optionally, the upper part of the rear leg is rigidly connected to the main truss, and the lower part is a jacking cylinder.

[0029] In another aspect, the application provides a method for passing through a hole of a double cantilever bridge girder erection machine, the double cantilever bridge girder erection machine comprising a main truss, a front crane, a rear crane, a front auxiliary leg, a front leg, a middle leg, and a rear leg, wherein the main truss is arranged along a construction direction, the front crane and the rear crane are arranged on the upper part of the main truss, and the front crane and the rear crane can move back and forth along the main truss in the construction direction, the upper part of the front crane and the rear crane is provided with a crane transverse moving mechanism to realize transverse moving of the hoisted girder to complete simultaneous erection of multiple girders; the front auxiliary leg, the front leg, the middle leg, and the rear leg are sequentially arranged on the lower part of the main truss, wherein the front auxiliary leg is arranged at the most front end, the front auxiliary leg, the front leg, the middle leg, and the rear leg can move back and forth along the construction direction, and the upper part of the front leg and the middle leg is provided with a transverse moving mechanism to realize transverse moving of the part above the main truss to complete simultaneous erection of multiple girders;

[0030] The method for passing through a hole of the double cantilever bridge girder erection machine comprises the following steps:

[0031] The front crane and the rear crane move to the middle position of the double cantilever bridge girder erection machine, and the jacking cylinder of the rear leg is retracted to disengage from the steel girder;

[0032] The safety anchoring device between the middle leg and the main truss is released, the longitudinal moving jacking cylinders of the middle leg and the front leg are started, the main truss is pushed to move in the construction direction, the front auxiliary leg is moved to above the pier, and the front leg is supported on the pier;

[0033] The main truss is anchored to the front leg, the rear leg is extended to support on the girder surface, the middle leg is retracted to disengage from the girder surface, the roller device of the middle leg is driven by the walking speed reducer to move the middle leg to a specified position behind the front leg in the construction direction, the middle leg is extended to support on the girder surface, and the middle leg is anchored to the main truss;

[0034] Release the front leg and the main truss anchoring, retract the front leg to the beam surface; start the walking reducer to drive the front leg of the supporting wheel device, so that the front leg moves to the designated position behind the front auxiliary leg in the construction direction, and the front leg is extended to support on the pier;

[0035] The front crane moves to the front end of the main truss in the construction direction, and the rear crane moves to the position directly above the middle leg; the rear leg is retracted to the beam surface.

[0036] Release the anchoring device between the middle leg and the main truss; start the longitudinal movement oil cylinder of the middle leg and the front leg, so that the main truss moves to the designated position in the construction direction; anchor the middle leg with the front leg and the main truss; pass through the hole to the position, and prepare to erect the steel beam.

[0037] Optionally, the bottom of the front leg is provided with a telescopic sleeve, the upper part of the front leg supports the main truss through the supporting wheel device, the upper part of the front leg is the supporting wheel device, and the lower part is anchored with the pier; the upper part of the middle leg is the supporting wheel device, and the lower part is supported by eight jacking oil cylinders; the upper part of the rear leg is rigidly connected with the main truss, and the lower part is provided with a jacking oil cylinder.

[0038] The above-described multiple parallel double-cantilever bridge erecting machine and the beam erecting and hole passing method thereof adopt the two-end cantilever beam erection, can erect multiple parallel bridges at the same time while meeting the large-span beam erection, reduce the hole passing bending moment, and reduce the weight of the whole machine. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a multiple parallel double-cantilever bridge erecting machine according to an embodiment of the present application.

[0040] Figures 2-7 It is a state diagram of a beam erecting process of the multiple parallel double-cantilever bridge erecting machine according to another embodiment of the present application.

[0041] Figures 8-13 It is a process state diagram of hole passing of the multiple parallel double-cantilever bridge erecting machine according to another embodiment of the present application. DETAILED DESCRIPTION

[0042] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0043] In this paper, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, the terms "system" and "network" are often used interchangeably in this paper.

[0044] like Figure 1 The diagram shown is a structural schematic of a double cantilever bridge erecting machine according to an embodiment of this application. The double cantilever bridge erecting machine includes a main truss 1, a front crane 2, a rear crane 3, a front auxiliary support leg 4, a front support leg 5, a middle support leg 6, a rear support leg 7, an electric hoist 8, a hoist 9, and a lifting beam 10. The lifting beam 10 is used to lift steel beams 11. In order to cooperate with the operation of the double cantilever bridge erecting machine, the double cantilever bridge erecting machine also includes a necessary hydraulic system (not shown) and an electrical system (not shown).

[0045] The main truss 1 travels along the construction direction. A front overhead crane 2 and a rear overhead crane 3 are mounted on top of the main truss 1, and these two cranes can move back and forth along the main truss 1. A lateral movement mechanism is provided on the upper part of the front and rear overhead cranes 2 and 3 to enable the lateral movement of the lifting beams to complete the simultaneous erection of multiple sections. In another embodiment of this application, the front overhead crane 2 includes a main lifting trolley and an auxiliary lifting trolley, the auxiliary lifting trolley being used for paving the bridge deck.

[0046] Below the main truss 1, the front auxiliary support leg 4, the front support leg 5, the middle support leg 6, and the rear support leg 7 are sequentially arranged. The front auxiliary support leg 4 is positioned at the foremost end. The front support leg 5 and the middle support leg 6 can be supported on bridge piers, and the rear support leg 7 can be supported on the completed bridge structure. The front auxiliary support leg 4, the front support leg 5, the middle support leg 6, and the rear support leg 7 are equipped with anti-roll wheels, allowing them to move back and forth along the construction direction. A lateral movement mechanism is installed on the upper part of the front support leg 5 and the middle support leg 6 to enable lateral movement of the upper part of the main truss, facilitating the simultaneous erection of multiple spans.

[0047] The front auxiliary support leg 4 adopts a C-shaped design. The bottom of the front support leg 5 is equipped with a telescopic sleeve. The upper roller device of the front support leg 5 supports the main truss 1. The upper part of the front support leg 5 is the roller device, and the lower part is anchored to the pier. The upper part of the middle support leg 6 is the roller device, and the lower part is supported by eight lifting cylinders. The upper part of the rear support leg 7 is rigidly connected to the main truss 1, and the lower part has lifting cylinders. The roller devices of the front support leg 5 and the middle support leg 6 are used to push the main truss forward by telescopically extending and retracting the cylinders when the bridge erecting machine passes through the span.

[0048] The electric hoist 8 can be placed at the last side of the main truss 1, i.e. the side that has been completed.

[0049] In another embodiment of the present application, as Figures 2-7 shown, a state diagram of the beam erection process of the double cantilever bridge girder erection machine of another embodiment of the present application, in combination with Figure 1 , the beam erection method of the double cantilever bridge girder erection machine can be as follows.

[0050] Step 201, the bridge girder erection machine is in the beam erection station state, the front beam carrying vehicle is positioned to carry the steel beam, the hoist of the front hoisting crane 2 is connected with the front end lifting point of the steel beam, and the front hoisting crane 2 lifts the steel beam to the front end of the steel beam to separate from the front beam carrying vehicle.

[0051] Step 202, the front hoisting crane 2 and the rear beam carrying vehicle move forward in linkage, the rear end lifting point of the steel beam is lowered to the rear hoisting crane 3 and then stopped, the hoist of the rear hoisting crane 3 is connected with the rear end lifting point of the steel beam, and the rear hoisting crane 3 lifts the steel beam to the rear end of the steel beam to separate from the rear beam carrying vehicle.

[0052] Step 203, the front hoisting crane 2 and the rear hoisting crane 3 walking system linkage longitudinal adjustment is in position, the front hoisting crane 2 and the rear hoisting crane 3 transverse system linkage transverse adjustment is in position, and the front hoisting crane 2 and the rear hoisting crane 3 lifting system linkage installs the steel beam at the specified position.

[0053] Step 204, the bridge girder erection machine hanger is fixedly connected with the newly installed steel beam and a certain pre-tightening force is applied, and the prefabricated bridge deck is installed on the steel beam by the front hoisting crane 2 and the rear hoisting crane 3.

[0054] Step 205, the connection between the steel beam and the hanger is released, and the bridge girder erection machine is prepared to pass through the hole.

[0055] As Figures 8-13 shown, a state diagram of the hole passing process of the double cantilever bridge girder erection machine of another embodiment of the present application, in combination with Figure 1 , the hole passing process of the double cantilever bridge girder erection machine can be as follows.

[0056] Step 301, the front hoisting crane 2 and the rear hoisting crane 3 walk to the middle position of the double cantilever bridge girder erection machine, and the oil cylinder of the rear support leg 7 is retracted to separate from the steel beam.

[0057] Step 302, the safety anchoring device between the middle support leg 6 and the main truss 1 is released, the longitudinal movement oil cylinder of the middle support leg 6 and the front support leg 5 is started, the main truss 1 is moved to the construction direction by pushing, the main truss 1 is moved forward to the position where the front auxiliary support leg 4 is above the pier, and the front support leg 5 is supported on the pier.

[0058] Step 303: The main truss 1 is anchored to the front support leg 5; the rear support leg 7 extends and supports the beam surface; the middle support leg 6 retracts until it is detached from the beam surface, and the travel reducer is started to drive the roller device of the middle support leg 6, so that the middle support leg 6 moves in the construction direction to the designated position behind the front support leg 5; the middle support leg 6 extends and supports the beam surface, and the middle support leg 6 is anchored to the main truss 1.

[0059] Step 304: Release the anchorage between the front outrigger 5 and the main truss 1, and retract the front outrigger 5 until it is detached from the beam surface; start the travel reducer to drive the front outrigger 5 roller device, so that the front outrigger 5 moves in the construction direction to the designated position behind the front auxiliary outrigger 4, and extends the front outrigger 5 hydraulic cylinder to support it on the pier.

[0060] Step 305: The front crane 2 moves in the construction direction to the front end of the main truss 1, and the rear crane 3 moves to directly above the middle support leg 6; the rear support leg 7 is retracted until it is detached from the beam surface.

[0061] Step 306: Release the anchoring device between the middle support leg 6 and the main truss 1; activate the longitudinal movement cylinders of the middle support leg 6 and the front support leg 5 to move the main truss 1 to the designated position in the construction direction; anchor the middle support leg 6 to the front support leg 5 and the main truss 1; the hole is in place, ready to erect the steel beam.

[0062] In summary, the double cantilever bridge erecting machine adopts a cantilever beam erection method at both ends, which can meet the requirements of large-span beam erection while reducing the bending moment across the span and reducing the overall weight of the machine.

[0063] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A multiple side-by-side double cantilever bridge girder erection machine characterized by, The double cantilever bridge girder erection machine comprises a main truss (1), a front crane (2), a rear crane (3), a front auxiliary support leg (4), a front support leg (5), a middle support leg (6) and a rear support leg (7), wherein, The front crane (2) and the rear crane (3) are arranged on the upper surface of the main truss (1) along the construction direction, and the front crane (2) and the rear crane (3) are movable along the main truss (1) along the construction direction, and the upper portions of the front crane (2) and the rear crane (3) are provided with a crane transverse moving mechanism to realize the transverse movement of the girder to complete the simultaneous erection of multiple girders. The front auxiliary support leg (4), the front support leg (5), the middle support leg (6) and the rear support leg (7) are sequentially arranged from front to rear on the lower surface of the main truss (1), wherein the front auxiliary support leg (4) is arranged at the front end, the front auxiliary support leg (4), the front support leg (5), the middle support leg (6) and the rear support leg (7) are movable along the construction direction, and anchor devices are arranged between the front support leg (5) and the main truss (1) and between the middle support leg (6) and the main truss (1) respectively to anchor the front support leg (5) and the main truss (1) or the middle support leg (6) and the main truss (1). The upper portions of the front support leg (5) and the middle support leg (6) are provided with a transverse moving mechanism to realize the transverse movement of the upper portion of the main truss to complete the simultaneous erection of multiple girders, the upper portion of the front support leg (5) is further provided with a roller device, the upper portion of the middle support leg (6) is also provided with a roller device, the roller device is used to support the main truss (1) and move the main truss in the construction direction by a longitudinal moving cylinder when the double cantilever bridge girder erection machine passes through a hole, and the roller device can also drive the corresponding front support leg (5) or middle support leg (6) to move in the construction direction under the drive of a walking reduction machine.

2. The multiple side-by-side double cantilever bridge erector of claim 1, wherein, The front support leg (5) supports the top surface of the pier, the middle portion of the front support leg (5) is a cross beam, the lower portion is anchored to the pier, the bottom of the front support leg (5) is provided with a telescopic sleeve to anchor the pier, the cross beam of the front support leg (5) is provided with a transverse moving mechanism to realize the transverse movement of the upper portion of the main truss, and the upper portion of the roller of the front support leg (5) is provided with a counter-hung wheel on both sides of the lower cover plate of the main beam to enable the front support leg (5) to move back and forth along the construction direction.

3. The multiple side-by-side double cantilever bridge girder erection machine of claim 1 wherein, The middle support leg (6) supports the beam end, the middle portion of the middle support leg (6) is a cross beam, and the lower portion is provided with eight jacking cylinders, the cross beam of the middle support leg (6) is provided with an anchor device to anchor the beam surface, and the lower portion of the middle support leg (6) is supported to the beam end by the jacking cylinders.

4. A plurality of side-by-side double cantilever bridge machines according to any one of claims 1 to 3, characterized in that, The upper portion of the rear support leg (7) is rigidly connected with the main truss (1), and the lower portion is supported to the beam surface by jacking cylinders.

5. A method of erecting a bridge with a plurality of juxtaposed double cantilever bridge erectors, characterized in that, The double cantilever bridge girder erection machine comprises a main truss (1), a front hoisting trolley (2), a rear hoisting trolley (3), a front auxiliary supporting leg (4), a front supporting leg (5), a middle supporting leg (6) and a rear supporting leg (7), wherein the main truss (1) is arranged along a construction direction, the front hoisting trolley (2) and the rear hoisting trolley (3) are arranged on the main truss (1), and the front hoisting trolley (2) and the rear hoisting trolley (3) are movable along the main truss (1) in the construction direction, a trolley transverse moving mechanism is arranged on the upper portion of the front hoisting trolley (2) and the rear hoisting trolley (3) to realize the transverse movement of the hoisted girder and complete the erection of multiple girders at the same time, the front auxiliary supporting leg (4), the front supporting leg (5), the middle supporting leg (6) and the rear supporting leg (7) are sequentially arranged below the main truss (1), the front auxiliary supporting leg (4) is arranged at the most front end, the front auxiliary supporting leg (4), the front supporting leg (5), the middle supporting leg (6) and the rear supporting leg (7) are movable along the construction direction, anchor devices are arranged between the front supporting leg (5) and the main truss (1) and between the middle supporting leg (6) and the main truss (1) respectively to anchor the front supporting leg (5) and the main truss (1) or the middle supporting leg (6) and the main truss (1), a transverse moving mechanism is arranged on the upper portion of the front supporting leg (5) and the middle supporting leg (6) to realize the transverse movement of the part above the main truss and complete the erection of multiple girders at the same time, the upper portion of the front supporting leg (5) is further provided with a supporting roller device, the upper portion of the front supporting leg (5) is provided with a longitudinal moving mechanism, the upper portion of the middle supporting leg (6) is also provided with a supporting roller device, the supporting roller device is used to support the main truss (1) and push the main truss to move in the construction direction through the longitudinal moving cylinder when the double cantilever bridge girder erection machine passes through a hole, and the supporting roller device can also drive the corresponding front supporting leg (5) or middle supporting leg (6) to move in the construction direction under the drive of a walking speed reducer; The girder erection method of the multiple parallel double cantilever bridge girder erection machines comprises the following steps: The double cantilever bridge girder erection machine is in a girder erection station state, a front girder carrying vehicle carries a steel girder to a position, a hoist of the front hoisting trolley (2) is connected with a front end lifting point of the steel girder, the front hoisting trolley (2) lifts the steel girder to separate the front end of the steel girder from the front girder carrying vehicle; The front hoisting trolley and a rear girder carrying vehicle move forward in linkage, a rear end lifting point of the steel girder is lowered to the rear hoisting trolley and then stopped, a hoist of the rear hoisting trolley (3) is connected with the rear end lifting point of the steel girder, the rear hoisting trolley (3) lifts the steel girder to separate the rear end of the steel girder from the rear girder carrying vehicle; The front hoisting trolley and the rear hoisting trolley move in longitudinal linkage, the front hoisting trolley and the rear hoisting trolley move in transverse linkage, and the front hoisting trolley and the rear hoisting trolley lift the steel girder to a specified position; The above steps are sequentially completed by the transverse movement of the front hoisting trolley and the rear hoisting trolley and the transverse movement of the main truss to erect other parallel girders. The double-cantilever bridge girder erection machine is connected with the new steel girder by the hanger and a certain pre-tightening force is applied to realize the girder arching, the precast bridge deck is installed on the steel girder by the front and rear lifting cranes (3); The connection between the steel girder and the hanger is released, and the bridge girder erection machine is ready for hole passing.

6. The method of bridging as claimed in claim 5, wherein, The middle part of the front leg (5) is a cross beam, the lower part is anchored to the pier, and the bottom of the front leg (5) is provided with a telescopic sleeve pier anchor.

7. The method of bridging according to claim 5, wherein, The lower part of the middle leg (6) has eight jacking oil cylinders.

8. The method of bridging according to any one of claims 5 to 7, wherein, The upper part of the rear leg (7) is rigidly connected with the main truss (1), and the lower part has a jacking oil cylinder.

9. A method of crossing a gap with a double cantilever bridge, characterized in that The double-cantilever bridge girder erection machine comprises a main truss (1), a front lifting crane (2), a rear lifting crane (3), a front auxiliary leg (4), a front leg (5), a middle leg (6), and a rear leg (7), wherein the main truss (1) is arranged along the construction direction, the front lifting crane (2) and the rear lifting crane (3) are arranged on the upper part of the main truss (1), and the front lifting crane (2) and the rear lifting crane (3) can move back and forth along the construction direction along the main truss (1), the front lifting crane (2) and the rear lifting crane (3) are provided with a crane transverse moving mechanism on the upper part to realize the transverse movement of the girder and complete the simultaneous erection of multiple bridges; the front auxiliary leg (4), the front leg (5), the middle leg (6), and the rear leg (7) are sequentially arranged on the lower part of the main truss (1), wherein the front auxiliary leg (4) is arranged at the most front end, the front auxiliary leg (4), the front leg (5), the middle leg (6), and the rear leg (7) can move back and forth along the construction direction, anchor devices are arranged between the front leg (5) and the main truss (1) and between the middle leg (6) and the main truss (1) respectively to anchor the front leg (5) and the main truss (1) or the middle leg (6) and the main truss (1); the front leg (5) and the middle leg (6) are provided with a transverse moving mechanism on the upper part to realize the transverse movement of the part above the main truss and complete the simultaneous erection of multiple bridges; the front leg (5) is further provided with a supporting roller device on the upper part, a longitudinal moving mechanism is arranged on the upper part of the front leg (5), the middle leg (6) is also provided with a supporting roller device, the supporting roller device is used to support the main truss (1) and push the main truss to move in the construction direction by the longitudinal moving cylinder when the double-cantilever bridge girder erection machine passes through the hole, and the supporting roller device can also drive the corresponding front leg (5) or middle leg (6) to move in the construction direction under the drive of a walking speed reducer; The hole passing method of the double-cantilever bridge girder erection machine comprises: The front lifting crane and the rear lifting crane walk to the middle position of the double-cantilever bridge girder erection machine, and the oil cylinder of the rear leg is retracted to be separated from the steel girder; The safety anchor device between the middle leg (6) and the main truss (1) is released, the longitudinal moving cylinders of the middle leg (6) and the front leg (5) are started, the main truss (1) is pushed to move in the construction direction, the main truss (1) moves forward to the position where the front auxiliary leg (4) is above the pier, and supports the front leg (5) on the pier; The main truss (1) is anchored with the front leg (5); the rear leg (7) is extended and supported on the beam surface; the middle leg (6) is retracted to be separated from the beam surface, the walking reduction machine is started to drive the roller device of the middle leg (6), so that the middle leg (6) moves to the rear of the front leg (5) to the specified position in the construction direction; the middle leg (6) is extended and supported on the beam surface, and the middle leg (6) is anchored with the main truss (1); The front leg (5) is unanchored with the main truss (1), and the front leg (5) is retracted to be separated from the beam surface; the walking reduction machine is started to drive the roller device of the front leg (5), so that the front leg (5) moves to the rear of the front auxiliary leg (4) to the specified position in the construction direction, and the front leg (5) is extended and supported on the pier; The front crane (2) moves to the front end of the main truss in the construction direction, and the rear crane moves directly above the middle leg (6); the rear leg (7) is retracted to be separated from the beam surface; The anchoring device between the middle leg (6) and the main truss (1) is released; the longitudinal movement oil cylinder of the middle leg (6) and the front leg (5) is started, so that the main truss (1) moves to the specified position in the construction direction; the middle leg (6) is anchored with the front leg (5) and the main truss (1); the hole is in place, and the steel beam is ready to be erected.

10. The via method of claim 9, wherein, The bottom of the front leg (5) is provided with an oil cylinder, the upper beam of the front leg (5) is rigidly connected with the main truss (1), and the lower part of the front leg (5) is anchored with the pier; the lower part of the middle leg (6) is supported by eight jacking oil cylinders; the upper part of the rear leg (7) is rigidly connected with the main truss (1), and the lower part is provided with a jacking oil cylinder.

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