A construction method for precast segmental beams under complex working conditions

Abstract

This invention discloses a construction method for precast segmental beams under complex working conditions. This method is based on a segmental assembly bridge erecting machine, which includes a main frame, front auxiliary legs, rear auxiliary legs, two middle legs, a first main gantry crane, a second main gantry crane, and two auxiliary gantry cranes. The first main gantry crane, the second main gantry crane, and the two auxiliary gantry cranes can move along the main frame. The construction method involves precasting the prestressed concrete box girder to be erected in segments at a dedicated beam fabrication yard, then transporting it to the bridge construction site and feeding it into the belly of the bridge erecting machine from the rear span for T-shaped cantilever assembly on a middle pier. Then, the first half-span cantilever assembly is performed. After the last half-span cantilever assembly of a section is completed, the entire section is prestressed. This invention utilizes a combination of gantry lateral movement and suspension lateral movement to adapt to the erection of curved beams with smaller radii, and employs leg lateral movement and rotation to adapt to the construction of bridges with small curves.

Description

Technical Field

[0001] This invention relates to the field of precast segmental beam construction technology, and in particular to a construction method for precast segmental beam construction under complex working conditions. Background Technology

[0002] In recent years, with the rapid development of road traffic and urban construction in major cities across the country, the construction environment of elevated bridge projects in cities has become more complex: the horizontal curves of the lines are small, the longitudinal slopes of the lines are large, the bridges are densely distributed and long, and the urban environment is inherently narrow, densely populated, and busy with traffic, which causes great interference to bridge construction. Therefore, more requirements have been put forward for bridge construction, and the precast segmental beam assembly technology has also been applied.

[0003] When constructing on steep slopes, it is necessary to take precautions to prevent the bridge erecting machine or main crane from slipping. However, the current bridge erecting machine's traveling mechanism is a wheel-rail system, and this rolling friction mechanism can easily cause slippage. At the same time, the current bridge erecting machine is difficult to erect curved beams with small radius.

[0004] In conclusion, in order to adapt to the rapid development of urban rail and highway transportation in the future, it is necessary to develop a new type of bridge erecting machine and its complete set of technologies that can meet the needs of the construction of large-span, small-curve, and steep-gradient bridges in urban rail transit projects, and to meet the needs of emerging beam technology. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a construction method for precast segmental beams under complex working conditions.

[0006] The technical solution adopted to achieve the above objectives is:

[0007] A construction method for precast segmental beams under complex working conditions is characterized in that the construction method is based on a segmental assembly bridge erecting machine, which includes a main frame, a front auxiliary leg, a rear auxiliary leg, two middle legs, a first main gantry crane, a second main gantry crane, and two auxiliary gantry cranes. The first main gantry crane, the second main gantry crane, and the two auxiliary gantry cranes are mounted on the main frame and can move along the main frame.

[0008] The front auxiliary legs and the rear auxiliary legs are respectively located at the front and rear ends of the main frame;

[0009] Both of the aforementioned middle support legs include a support assembly and a first lifting assembly. The first lifting assembly is located below the support assembly. The middle support legs are slidably located below the main frame via the support assembly. The support assembly mainly consists of two shifting trolleys, a transverse shifting mechanism, a longitudinal shifting mechanism, and a support leg beam. The shifting trolleys are divided into an upper part and a lower part. The lower part of the shifting trolley is located on the support leg beam, and the upper part of the shifting trolley is connected to the main frame. The upper part of the shifting trolley can rotate along the central axis of the lower part of the shifting trolley. The transverse shifting mechanism drives the shifting trolley to move laterally on the support leg beam, and the longitudinal shifting mechanism pushes the main frame.

[0010] The front auxiliary outrigger includes a second lifting assembly, a rotating assembly, and a first fixing assembly. The second lifting assembly is located at the front end of the main frame, and the rotating assembly and the fixing assembly are sequentially located below the second lifting assembly. The first fixing assembly can rotate a certain angle on the second lifting assembly through the rotating assembly.

[0011] The rear auxiliary support leg includes a third lifting component and a second fixing component. The third lifting component is located at the rear end of the main frame, and the second fixing component is located below the third lifting component.

[0012] The construction method includes the following steps:

[0013] (i) The first span of the bridge erecting machine is in place, the two middle legs are supported on the pier top block, the front auxiliary legs and the rear auxiliary legs are detached, and the bridge erecting machine is ready to erect the beam.

[0014] (ii) The first main crane and the second main crane lift the first segment beam to both sides of the middle support leg in front of the construction site in sequence. The initial alignment is adjusted by adjusting the elevation and the aerial posture of the segment block. Then the wet joint size is adjusted, and the fine alignment is carried out. The temporary prestressing tensioning, the installation of the wet joint template between the T structure and the T structure are completed in sequence, and the wet joint is poured. After the wet joint reaches the design strength, the internal permanent prestressing steel strand tensioning is carried out.

[0015] (iii) Repeat step (ii) and erect the T-structures of the piers where the middle support legs are located in front of the construction in sequence and symmetrically until the last pair of segment beams of the middle span T-structure are assembled.

[0016] (iv) After the first T-structure of each section is erected, the first side span segment beam suspension construction shall be carried out;

[0017] (v) The first and second main cranes travel to the vicinity above the two middle support legs respectively, and drive the middle support leg lateral movement mechanism to adjust the main frame of the bridge erecting machine to a suitable position before the span.

[0018] (vi) The first main crane, the second main crane and the auxiliary crane move to the tail of the bridge erecting machine and use the longitudinal movement mechanism of the middle support leg to push the main frame forward until the front auxiliary support leg reaches the top of the pier block in front.

[0019] (vii) Simultaneously support the front auxiliary outrigger and the rear auxiliary outrigger, detach the rear middle outrigger, and move the rear middle outrigger of the first main crane to the top of the pier behind the front auxiliary outrigger to support the middle outrigger and install the middle outrigger pier top anchoring device.

[0020] (viii) After the front and rear auxiliary legs are removed, the first main crane, the second main crane and the auxiliary crane move to the front end of the bridge erecting machine. The main frame is pushed forward by the longitudinal movement mechanism of the middle support leg until the main frame moves forward to the beam erection position. The bridge erecting machine is ready to pass through the span again.

[0021] (ix) Repeat steps (ii) to (iii) to complete the "T" structure erection of the intermediate pier of the bridge;

[0022] (x) The first main crane and the second main crane are respectively moved to the vicinity above the front and rear middle support legs, and the middle support leg transverse movement mechanism is driven to adjust the main frame of the bridge erecting machine to a suitable position before the span, in preparation for the final span of the span to pass through the span.

[0023] (xi) When the first main crane, the second main crane and the auxiliary crane move to the tail of the bridge erecting machine, the longitudinal movement mechanism of the middle support leg pushes the main frame forward until the front auxiliary support leg reaches the support frame above the pier and is supported on the pier support.

[0024] (xii) Use the first main crane to place a segment beam on the top of the side span pier into place;

[0025] (xiii) Repeat step (xiv) to install the other segment beam on the pier top and temporarily anchor the two pier top blocks to ensure that they can meet the support requirements of the middle support leg.

[0026] (xiv) Supporting auxiliary legs after detachment, and the middle support leg after detachment;

[0027] (xv) The first main crane lifts the middle support leg behind the front auxiliary support leg to the top of the pier. The first main crane, the second main crane and the auxiliary crane move to the front end of the bridge erecting machine, disengage the front auxiliary support leg and the rear auxiliary support leg, and the bridge erecting machine is ready to cross the span again.

[0028] (xvi) Using the longitudinal movement mechanism of the middle support leg, the main frame is pushed forward to the beam erection position, the last span of the first section is constructed, the intermediate wet joint is poured, and the permanent stress steel strands of the entire span are tensioned, thus completing the construction of the first section.

[0029] Furthermore, in steps (i), (ii), and (iii), when the bridge erecting machine is performing T-shaped cantilever splicing, the front and rear auxiliary cranes respectively suspend the tensioning platform on both sides of the segment beam to be installed, serving as the operating platform for personnel. When the line is curved, before the first and second main cranes lift the segment beam, the entire machine is moved laterally to a suitable position in advance to avoid moving the entire machine laterally while the first and second main cranes are lifting the segment beam.

[0030] When the entire machine needs to be moved laterally, the first and second main cranes are positioned above the front and rear middle support legs, respectively.

[0031] Furthermore, in step (iv), the suspension construction of the first side span segment beam is carried out according to the following steps:

[0032] (1) The segmental beam is suspended segment by segment from the edge to the mid-span.

[0033] (2) Transport the beam to the position and install the lifting rod, control the first main crane to lift the beam, and at the same time use the lifting rod and the hanging to suspend the segment beam block on the main frame. Repeat the above steps until the first span segment beam is completely suspended and assembled.

[0034] (3) The first main crane is used to adjust the segment beam in three-dimensional space and perform initial alignment in sequence, then apply epoxy resin, then perform precise alignment and temporary prestressing tensioning, then install wet joint template and pour wet joint, and then perform permanent stress steel strand tensioning of the whole span.

[0035] (4) After the entire span is tensioned, the hanging is unloaded and removed.

[0036] Furthermore, in steps (v) and (x), when the bridge erecting machine is crossing a curved section, the transverse movement mechanism inside the middle support leg needs to drive the shifting trolley to carry the main frame through a certain transverse amplitude and control the shifting trolley to rotate a certain angle. The specific steps include:

[0037] (1) The middle support leg lateral movement mechanism drives the whole machine to laterally move a certain distance so that the main frame at one of the middle support legs moves laterally to the target position;

[0038] (2) Using the center line of the shifting trolley of one of the middle legs of the main frame reaching the target position as the pivot, drive the lateral shifting mechanism of the other middle leg to continue to carry the main frame to the target position.

[0039] (3) During the process of the lateral movement mechanism driving the whole machine to move laterally, the angle between the support leg beam and the main frame will change, and the distance between the two shifting trolleys of a single middle support leg on the support leg beam will change. Therefore, after the lateral movement mechanism of the middle support leg drives the whole machine to move laterally a certain distance, the connecting rod between the two shifting trolleys needs to be loosened, the length of the connecting rod is adjusted, and then the shifting trolleys are connected. After the connecting rod is connected, the machine continues to move laterally. This process is repeated several times until the target lateral movement is achieved.

[0040] Furthermore, in steps (vi) and (xi), when the bridge erecting machine passes through the arch on a curved section and the front auxiliary outrigger is positioned on the support on the top of the pier or beside the pier, the following steps need to be followed:

[0041] (1) When the front auxiliary outrigger reaches the center of the pier top, release the bolt connection between the upper and lower crossbeams at the lower end of the front auxiliary outrigger;

[0042] (2) Drive the lower crossbeam to rotate, so that the lower crossbeam of the front auxiliary leg 2 is basically parallel to the pier or the pier-side support, and reconnect the bolts between the two crossbeams;

[0043] (3) Continue forward to the designated position and support the anchor beam or the pier support;

[0044] (4) Effectively anchor the lower crossbeam of the front auxiliary leg to the anchoring longitudinal beam or the side of the pier to prevent it from sliding.

[0045] Furthermore, in steps (vii) and (xv), the passage through the middle support leg behind the first main crane after hoisting needs to be done according to the following steps:

[0046] (1) The front auxiliary crane travels to the front end of the main frame 1;

[0047] (2) Connect the lifting device of the first main crane to the rear middle support leg, and lift the rear middle support leg of the first main crane to detach it;

[0048] (3) The first main crane lifts the rear middle support leg and moves forward to the middle position of the rear span. The first main crane drives the middle support leg to rotate 90 degrees clockwise, and then continues to move forward.

[0049] (4) The first main crane lifts the rear middle support leg to the middle position of the front span and descends and rotates 90 degrees counterclockwise;

[0050] (5) The first main crane lifts the middle support leg and continues to move forward to the position of the pier top behind the front auxiliary support leg.

[0051] Furthermore, during the process of hoisting the first main crane's rear support leg through the hole:

[0052] (1) During the process of the first main crane reversing the outrigger, the lifting device rotation mechanism of the main crane has two 90° rotation movements, and the two rotations are in opposite directions;

[0053] (2) When the middle support leg of the first main crane is detached and cannot be balanced, the two shifting trolleys of the middle support leg are adjusted to serve as weights to balance it. Then the position of the shifting trolleys is fixed and the middle support leg is continued to be hoisted forward.

[0054] Furthermore, in step (twelfth), the first main crane needs to place a segmental beam on the top of the side span pier into position according to the following steps:

[0055] (1) The front auxiliary crane moves to the front end of the main frame, and the first main crane moves forward about 20m;

[0056] (2) At the same time, the second main crane is used to move the rear auxiliary leg forward to the rear of the middle leg, and temporarily hang it on the lower chord of the main frame with threaded steel bars;

[0057] (3) Use the second main crane to move the segmental beam to the two middle support spans and place it on the bridge deck;

[0058] (4) The second main crane returns to the tail of the main frame to continue picking up beams, and the lifting device of the first main crane is reconnected to the segmental beams in the span;

[0059] (5) Use the first main crane to move the segmental beam to the vicinity of the front span pier;

[0060] (6) The first main crane rotates the segmental beam by 90 degrees;

[0061] (7) The first main crane places the first half segment beam on the pier top into place;

[0062] (8) Temporarily support and fix the segmental beams to the piers.

[0063] Furthermore, in step (fourteen), the method of supporting the auxiliary outrigger and detaching the middle outrigger is as follows:

[0064] (1) When the second main crane moves to the end of the main frame, the second main crane is used to move the rear auxiliary leg backward to a suitable position and bolt it to the lower chord of the main frame to support the rear auxiliary leg;

[0065] (2) The hoisting device that connects the first main crane hoist and the rear middle support leg, and the first main crane lifts the rear middle support leg to detach.

[0066] Furthermore, both the first and second main cranes include two first traveling mechanisms, a hoisting mechanism, and a lifting beam assembly. The two first traveling mechanisms are driven by pin gears, and the first and second main cranes move along the top of the main frame through the first traveling mechanisms.

[0067] The hoisting winch mechanism is connected to the lifting beam assembly via a wire rope. The lifting beam assembly is equipped with a three-dimensional adjustment device for adjusting the angle of the lifting beam assembly. The lifting beam assembly is also equipped with components for hoisting the front auxiliary outrigger, the rear auxiliary outrigger, and the middle outrigger.

[0068] The beneficial effects of this invention are as follows:

[0069] 1. This invention employs a method of first prefabricating prestressed concrete box girders in sections at a dedicated beam fabrication yard, then transporting them to the bridge construction site and feeding them into the belly of the bridge erecting machine from the rear span for T-shaped cantilever assembly on a middle pier. This is followed by cantilever assembly of the first half-span, and finally, the prestressing tensioning of the entire span is carried out after the cantilever assembly of the last half-span is completed. This method also utilizes the coordinated lateral movement of the overhead crane and the lateral movement of the suspended structure to adapt to the erection of curved beams with smaller radii. Furthermore, it employs lateral movement and rotation of the outriggers to adapt to the construction of bridges on small curved sections, enabling construction through spans on small curved sections. This increases the safety of span crossings, ensures construction safety under various complex working conditions, improves construction efficiency, avoids traffic disruption, and prevents environmental pollution.

[0070] 2. The construction method of this invention can construct two bridge spans simultaneously, and abandons the original hydraulic cylinder pushing method for lateral movement, adopting a chain wheel drive method, which makes the entire construction process fast and safe, and meets the requirements of alternating lateral erection of two spans to complete the lateral movement of equipment.

[0071] 3. In this invention, when the main crane is hoisting the middle support leg, the lifting device on the main crane drives the middle support leg to rotate 90 degrees in opposite directions twice, ensuring the normal power supply to the middle support leg during subsequent construction. Attached Figure Description

[0072] Figure 1 This is a schematic diagram of the overall T-structure of the present invention;

[0073] Figure 2 This is a schematic diagram of the overall half-span full-load erection of the present invention;

[0074] Figure 3 This is a top view of the main frame in this invention;

[0075] Figure 4 This is the front view of the main frame in this invention;

[0076] Figure 5 For the present invention Figure 4 Sectional view at point AA;

[0077] Figure 6 For the present invention Figure 4 Sectional view at point BB;

[0078] Figure 7 This is a front view of the front auxiliary support leg structure in this invention;

[0079] Figure 8 This is a side view of the front auxiliary support leg structure in this invention;

[0080] Figure 9 This is a schematic diagram of the support leg structure in this invention;

[0081] Figure 10 This is a schematic diagram of the lifting assembly in the outrigger structure of the present invention;

[0082] Figure 11 This is a front view of the rear auxiliary support leg structure in this invention;

[0083] Figure 12 This is a side view of the rear auxiliary support leg structure in this invention;

[0084] Figure 13 This is a front view of the first main crane structure in this invention;

[0085] Figure 14 This is a side view of the first main crane structure in this invention;

[0086] Figure 15 This is a front view of the second main crane structure in this invention;

[0087] Figure 16 This is a side view of the second main crane structure in this invention;

[0088] Figure 17 This is a front view of the auxiliary crane structure in this invention;

[0089] Figure 18 This is a side view of the auxiliary crane structure in this invention;

[0090] Figure 19 This is a schematic diagram of the structure of a single hanging unit in the hanging assembly of the present invention;

[0091] Figure 20 For the present invention Figure 19 Diagram of direction A in the middle;

[0092] Figure 21 For the present invention Figure 19 Diagram of direction B in the middle;

[0093] Figure 22 For the present invention Figure 19 Sectional view at CC;

[0094] Figure 23 This is a schematic diagram of the structure of the wet joint construction platform in this invention;

[0095] Figure 24 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 1 ;

[0096] Figure 25 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 ;

[0097] Figure 26 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 3 ;

[0098] Figure 27 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 4 ;

[0099] Figure 28 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 5 ;

[0100] Figure 29 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 6 ;

[0101] Figure 30 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 7 ;

[0102] Figure 31 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 8 ;

[0103] Figure 32 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 9 ;

[0104] Figure 33 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 ;

[0105] Figure 34 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 one;

[0106] Figure 35 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 two;

[0107] Figure 36 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 three;

[0108] Figure 37 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 Four;

[0109] Figure 38 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 five;

[0110] Figure 39 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 six;

[0111] Figure 40This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 seven;

[0112] Figure 41 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 eight;

[0113] Figure 42 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 10 Nine;

[0114] Figure 43 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 ten;

[0115] Figure 44 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 eleven;

[0116] Figure 45 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 twelve;

[0117] Figure 46 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 Thirteen;

[0118] Figure 47 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 fourteen;

[0119] Figure 48 This is a schematic diagram of the construction process of the bridge erecting machine construction method in this invention. Figure 2 fifteen.

[0120] Among them, 1-main frame, 1a-main beam, 1b-connecting beam, 1c-track square steel, 1d-drive rail, 1e-suspending rail, 1f-vehicle stop, 2-front auxiliary outrigger, 2a-hinge assembly, 2b-first upper crossbeam, 2c-column outer sleeve, 2d-first intermediate crossbeam, 2e-first inner column, 2f-first lifting cylinder, 2g-first lower crossbeam, 2h-spreader beam, 2i-electric rotating shaft, 2j-anchoring longitudinal beam, 2k-threaded steel bar, 3-middle outrigger, 3a-displacement Trolley, 3b-Longitudinal movement mechanism, 3c-Transverse movement mechanism, 3d-Connecting rod, 3e-Outrigger crossbeam, 3f-Support crossbeam, 3g-Third inner sleeve column, 3h-Outer sleeve lifting section, 3i-Third lifting cylinder, 3j-Cylinder lifting section, 3k-Cylinder crossbeam, 3l-Adjustable support, 3m-Bottom crossbeam, 3n-Scissor brace, 3o-Anchoring device, 4-Rear auxiliary outrigger, 4a-Second inner sleeve column, 4b-Second upper crossbeam, 4c-Second middle crossbeam, 4d-Second lower crossbeam, 4e- 4f - connecting crossbeam, 4g - diagonal brace, 4h - second lifting cylinder, 5 - first main crane, 5a - crane gantry, 5b - crossbeam assembly, 5c - first traveling mechanism, 5d - hoisting winch mechanism, 5e - lifting beam assembly, 6 - second main crane, 6a - crane gantry, 6b - crossbeam assembly, 6c - first traveling mechanism, 6d - hoisting winch mechanism, 6e - lifting beam assembly, 6f - first electric hoist, 7 - auxiliary crane, 7a - second traveling mechanism, 7b - auxiliary crane Car gantry, 7c-5t electric hoist, 7d-10t electric hoist, 7e-counterweight block, 8-tensioning platform, 9-suspension assembly, 9a-long hanger, 9b-transverse beam, 9c-balance beam, 9d-hook, 9e-long crossbeam, 9f-short hanger, 10-wet joint construction platform, 10a-lower frame, 10b-upper frame, 10c-strut, 10d-tie rod, 10e-adjustable strut, 10f-beam surface horizontal strut, 10g-threaded steel bar, 10h-movable ladder.

[0121] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Detailed Implementation

[0122] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0123] like Figure 1-23As shown, this embodiment discloses a construction method for precast segmental beam construction under complex working conditions, based on a novel segmental assembly bridge erecting machine. The bridge erecting machine includes a main frame 1, front auxiliary legs 2, two sets of middle legs 3, rear auxiliary legs 4, a first main crane 5, a second main crane 6, an auxiliary crane 7, a tensioning platform 8, a hanging assembly 9, and a wet joint construction platform 10.

[0124] like Figure 1-6 The main frame 1 shown consists of two truss-type main beams 1a and a connecting beam 1b. The main beams 1a adopt an equilateral triangular double-layer truss structure, and the connecting beams 1b adopt an inverted triangular truss structure. The main frame 1 is symmetrical in both the transverse and longitudinal directions. A track square steel 1c is installed along the middle of the top of the upper chord of the two main beams 1a. A drive track 1d for the gear reducer is installed along the top of the upper chord of the two main beams. A suspension track 1e is installed in the middle of the lower chord of the two main beams. A vehicle stop 1f is installed at the end of the upper chord of the two main beams. This main frame adopts a double-layer triangular truss structure and is a fully symmetrical structure, which facilitates the reverse construction of this bridge erecting machine.

[0125] like Figure 1-8 As shown, the front auxiliary support leg 2 is a fixed support leg. Its upper end is hinged to the front end of the main beam 1a, and its lower end is supported on the pier or the temporary support next to the pier. It is not only a temporary support when the bridge erecting machine passes through the span, but also a heavy-duty support when the bridge erecting machine erects the pier top block and the 0# block. The front auxiliary support leg 2 includes a hinge assembly 2a, a first upper crossbeam 2b, a column outer sleeve 2c, a first middle crossbeam 2d, a first inner column 2e, a first lifting cylinder 2f, a first lower crossbeam 2g, a spreader beam 2h, an electric rotating shaft 2i, and an anchoring longitudinal beam 2j. The hinge assembly 2a, the first upper crossbeam 2b, the first middle crossbeam 2d, the first inner column 2e, the first lifting cylinder 2f, and the first lower crossbeam 2g form the second lifting assembly, the electric rotating shaft 2i forms the rotating assembly, and the spreader beam 2h and the anchoring longitudinal beam 2j form the first fixed assembly.

[0126] like Figure 1-8 As shown, the upper part of the hinge assembly 2a is bolted to the bottom of the lower chord of the main beam 1a. The lower part of the hinge assembly 2a is directly welded to the first upper crossbeam 2b. The lower part of the first upper crossbeam 2b is welded to the column outer sleeve 2c to form an integral frame. Square holes are opened in the welding area of ​​the first upper crossbeam 2b in the column outer sleeve 2c. The first intermediate crossbeam 2d is connected to the first inner sleeve column 2e by a pin. The first lifting cylinder 2f is connected between the first upper crossbeam 2b and the first intermediate crossbeam 2d. The lower part of the first inner sleeve column 2e is bolted to the first lower crossbeam 2g. An electric rotating shaft 2i is set between the first lower crossbeam 2g and the spreader beam 2h. The spreader beam 2h can rotate along the electric rotating shaft 2i on the first lower crossbeam 2g. The spreader beam 2h is supported on the anchoring longitudinal beam 2j. The anchoring longitudinal beam 2j is connected to the pre-embedded threaded steel bar 2k on the top of the pier.

[0127] like Figure 1-10 As shown, there are two sets of middle support legs 3 with identical structures. These are movable support legs. The upper end of the middle support leg 3 is slidably supported on the lower chord of the main beam 1a, and the lower end is supported on the pier top block and #0 block via adjustable support 3l. The middle support leg 3 is a heavy-duty support during bridge erection by the bridge erecting machine. It also works in conjunction with the front auxiliary support leg 2 and the rear auxiliary support leg 4 to complete the equipment passage through the opening. Each set of middle support legs 3 includes two shifting trolleys 3a, a longitudinal shifting mechanism 3b, a transverse shifting mechanism 3c, a connecting rod 3d, a support leg crossbeam 3e, and a support... The first lifting assembly consists of a support beam 3f, two third inner sleeve columns 3g, an outer lifting section 3h, a third lifting cylinder 3i, a cylinder lifting section 3j, a cylinder beam 3k, an adjustable support 3l, a bottom beam 3m, a scissor brace 3n, and an anchoring device 3o. Two shifting trolleys 3a and a support leg beam 3e form a support assembly. The support beam 3f, the two third inner sleeve columns 3g, the third lifting cylinder 3i, the cylinder beam 3k, and the adjustable support 3l form a single lifting unit within the first lifting assembly.

[0128] like Figure 1-10 There are two shifting trolleys 3a. The longitudinal shifting mechanism 3b is set on the shifting trolley 3a. The shifting trolley 3a is supported on the bottom of the lower chord of the single main beam 1a by the longitudinal shifting mechanism 3b. In this embodiment, the longitudinal shifting mechanism is the prior art. It can push the main beam 1a on the main frame 1 to move forward. Each shifting trolley 3a is divided into an upper part and a lower part. The lower part of the shifting trolley 3a is set on the support leg beam 3e. The upper part of the shifting trolley 3a is supported on the bottom of the lower chord of the single main beam 1a by the longitudinal shifting mechanism 3b. The upper part of the shifting trolley can rotate along the central axis of the lower part of the shifting trolley. An anchor is provided between the shifting trolley 3a and the lower chord of the main beam 1a. In the bridge erecting machine beam erection operation, this anchoring mechanism needs to be installed in place. A connecting rod 3d is set between the two shifting trolleys 3a.

[0129] The lateral movement mechanism 3c is located at one end of the support leg beam 3e. The lateral movement mechanism 3c adopts a chain drive, breaking away from the conventional method of using hydraulic cylinders to push the entire bridge erecting machine laterally. It can meet the requirements of alternating lateral erection of two spans and complete the lateral movement of the equipment, resulting in high overall construction speed and good safety in the overall construction process. The lateral movement mechanism 3c is equipped with a chain and a drive wheel that meshes with the chain. The other end of the support leg beam 3e is equipped with a driven wheel that meshes with the chain. The lateral movement mechanism 3c drives the drive wheel to rotate, thereby driving the chain to move. At the same time, the shifting trolley 3a is located on the chain. That is, when the lateral movement mechanism 3c drives the chain to move, it simultaneously drives the shifting trolley 3a to move laterally on the support leg beam 3e.

[0130] The support beam 3f is bolted to the bottom of the outrigger beam 3e. A single middle outrigger 3 has four support beams 3f. Each support beam 3f is connected to two third inner sleeve columns 3g via pins. An outer sleeve extension section 3h is installed between the support beam 3f and the third inner sleeve columns 3g. The outer sleeve extension section 3h is connected to the support beam 3e via flange bolts, and to the inner sleeve columns 3g via pins. The top of the third lifting cylinder 3i is bolted to the bottom of the support beam 3e, and the bottom is bolted to the top of the cylinder beam 3k. Between the third lifting cylinder 3i and the cylinder beam 3k... The system is equipped with a hydraulic cylinder raising section 3j, a hydraulic cylinder crossbeam 3k connected to two third inner sleeve columns 3g via pins in the form of an outer sleeve column, and a bottom crossbeam 3m with four individual legs. Each bottom crossbeam 3m is connected to two third inner sleeve columns 3g via flange bolts. An adjustable support 3l is bolted to the bottom of each bottom crossbeam 3m. A scissor brace 3n is pinned to the outer sleeve raising section 3h to increase the lateral stability of the leg in the high position. An anchoring device 3o is bolted to the leg crossbeam 3e and can be fixed at different positions on the leg crossbeam 3e. The bottom of the anchoring device 3o is connected to the pier top block.

[0131] In this invention, the middle support leg 3 adopts the method of lateral movement and rotation to adapt to the construction of bridges with small curves, realize the equipment to pass through the holes in the small curves, and increase the safety of the equipment passing through the holes.

[0132] like Figure 11-12 As shown, the rear auxiliary support leg of the present invention mainly includes a second inner sleeve column 4a, a second upper crossbeam 4b, a second middle crossbeam 4c, a second lower crossbeam 4d, a pad block 4e, a connecting crossbeam 4f, a diagonal brace 4g, and a second lifting cylinder 4h. The second inner sleeve column 4a, the second upper crossbeam 4b, the second middle crossbeam 4c, the connecting crossbeam 4f, and the second lifting cylinder 4h form a third lifting assembly, while the second lower crossbeam 4d and the pad block 4e form a second fixing assembly.

[0133] like Figure 1-12 As shown, the connecting beam 4f is formed by welding four I-shaped crossbeams into an integral frame, which is bolted to the lower chord of the main beam 1a, and forms an integral unit with the second inner sleeve column 4a and the diagonal brace 4g. The upper part of the second upper beam 4b is hinged to the connecting beam 4f, and its two sides are connected to the second inner sleeve column 4a by pins. It is bolted to the second lifting cylinder 4h in the middle. The two sides of the second middle beam 4b are connected to the second inner sleeve column 4a by pins, and its middle is bolted to the second lifting cylinder 4h. The upper part of the second lower beam 4d is connected to the second inner sleeve column 4a by flange bolts, and the lower part is connected to the pad 4e by bolts. The pad 4e is directly supported on the concrete beam surface.

[0134] like Figure 1-14As shown, the first main crane 5 in this invention includes a crane gantry 5a, a crossbeam assembly 5b, a first traveling mechanism 5c, a hoisting mechanism 5d, and a lifting beam assembly 5e. The hoisting mechanism 5d is fixed on the crossbeam assembly 5b, and the crossbeam assembly 5b is slidably disposed on the crossbeam of the crane gantry 5a. The crossbeam assembly 5b and the crane gantry 5a can slide relative to each other. The hoisting mechanism 5d is connected to the lifting beam assembly 5e via a wire rope. The crane lifting beam assembly 5e is equipped with a three-dimensional adjustment device. In this embodiment, the three-dimensional adjustment device is existing technology and can adjust the lifting beam assembly 5e at multiple angles, thereby adjusting the flatness of the lifting device. The larger size makes it more suitable for assembling beams on larger longitudinal and transverse slopes. The crane beam assembly 5e is equipped with components for hoisting the front auxiliary support leg 2, the middle support leg 3, and the rear auxiliary support leg 4. The first traveling mechanism 5c consists of four wheel boxes, which are hinged to the crane gantry 5a by pin shafts. The first traveling mechanism 5c consists of four wheel boxes and adopts pin drive. The braking adopts motor braking, which makes the drive braking more reliable and effectively solves the problem of slope slippage. Moreover, the pin drive does not require high manufacturing precision, which is more conducive to use on bridge erecting machines with complex working conditions. The first traveling mechanism 5c is located in the drive track 1d of the upper chord of the main beam 1a inside the main frame 1.

[0135] like Figure 15-16 As shown, the second main crane 6 in this invention has a basically the same structure as the first main crane 5. The difference is that the crane gantry 6a of the second main crane 6 is equipped with a cantilever beam and two 5t first electric hoists 6f are provided at both ends of the cantilever beam for hoisting the wet joint construction platform.

[0136] like Figure 1-18 As shown, in this invention, there are two sets of auxiliary cranes 7, which are respectively arranged at the front and rear ends of the first main crane 5 and the second main crane 6. The auxiliary crane 7 includes a second traveling mechanism 7a, an auxiliary crane gantry 7b, a 5t electric hoist 7c, a 10t electric hoist 7d, and a counterweight 7e. The traveling mechanism 7a consists of two sets of traveling wheel boxes, which act on the drive rails 1d of the upper chord of the two main beams 1a of the main frame 1. The traveling mechanism 7a is driven by pin gear transmission and braked by electric motor. The auxiliary crane gantry 7b consists of a box-shaped main beam and four support columns. The upper and lower ends of the support columns are connected to the main beam of the gantry and the traveling wheel boxes, respectively, forming a stable triangular structure along the bridge. The crane gantry 7b is provided with rails for the 10t hoist 7d and two 5t hoists 7c to run on. The crane gantry 7b is provided with a counterweight 7e to ensure the stability of the auxiliary crane 7 itself when the 10t hoist 7d is hoisted.

[0137] like Figure 1-22As shown, the suspension mechanism 9 in this invention consists of multiple suspension units. Each suspension unit includes a long suspension rod 9a, a transverse beam 9b, a balance beam 9c, a hook 9d, a long crossbeam 9e, and a short suspension rod 9f. There are four long suspension rods 9a, the upper part of which is connected to the suspension track 1e of the lower chord of the main beam 1a and can move longitudinally along the groove of the suspension track 1e. The lower part of every two long suspension rods 9a is connected to the transverse beam 9b and the balance beam 9c, respectively. The two sides of the transverse beam 9b are directly hooked to the ear beams on both sides of the lower crossbeam 9e. The balance beam 9c is hinged to the hook 9d through a pin. The hook 9d mechanism is directly hooked to the ear beam of the lower crossbeam 9e, thus forming a stable form of four-point lifting and three-point balance.

[0138] like Figure 23 As shown, the wet joint construction platform 10 of this invention includes a lower frame 10a, an upper frame 10b, a strut 10c, a tie rod 10d, an adjustable strut 10e, a horizontal beam strut 10f, a threaded steel bar 10g, and a movable ladder 10h. The lower frame 10a is a rectangular truss structure welded from steel profiles and plates, and there are two of them, connected in the middle by flange bolts. A single lower frame 10a and a single upper frame 10b are hinged by a pin. Multiple struts are arranged between the upper frame 10b and the lower frame 10a. Rod 10c forms a stable structure for the upper and lower frames. The upper end of the upper frame 10b is connected to the tie rod 10d by a pin. The tie rod 10d, the horizontal support rod, and the adjustable support rod 10e are connected by pins to form a stable "P"-shaped structure. The two sets of "P"-shaped structures are directly hung on the concrete beam surface. The upper and lower parts of the two sets of "P"-shaped structures are connected by bolts and steel bars 10f. The movable ladder is directly hooked onto the lower frame 10a and the upper frame 10b to facilitate the movement of people up and down.

[0139] In this invention, when the bridge erecting machine is in use, the first lifting cylinder 2f in the front auxiliary leg 2 moves the first inner sleeve column 2e through the first intermediate crossbeam 2d, thereby giving the front auxiliary leg 2 a large vertical adjustment range. In the middle support leg 3, the third lifting cylinder 3i, the cylinder extension section 3j, and the outer extension section 3h work together to move the cylinder crossbeam 3k through the third lifting cylinder 3i, thereby moving the third inner sleeve column 3g. Furthermore, the number of cylinder extension sections 3j and outer extension sections 3h can be adjusted according to the specific construction conditions to further increase the vertical adjustment range of the middle support leg. In the rear auxiliary support leg 4, the second lifting cylinder 4h moves the second lower crossbeam 4c, thereby moving the second inner sleeve column 4a, thereby giving the rear auxiliary support leg 4 a large vertical adjustment range. This allows the equipment to adapt to the use of lines with large longitudinal slopes.

[0140] The chain on the control transverse movement mechanism 3c of the middle support leg 3 moves, thereby driving the shifting trolley 3a to move along the chain on the support leg beam 3e, thus realizing the transverse movement of the middle support leg, and thus enabling the equipment to adapt to the use of lines with large cross slopes.

[0141] By controlling the first lower crossbeam 2g to rotate along the electric rotating shaft 2i on the spreader beam 2h, the front auxiliary outrigger can be rotated at a small angle. By controlling the shifting trolley 3a to rotate at a certain angle, the middle outrigger can be rotated at a small angle, which makes it easier for the equipment to adapt to small curve construction.

[0142] like Figure 24-48 As shown in the figure, this embodiment describes a construction method for precast segmental beams under complex working conditions. Taking the construction of a bridge with three spans as a unit by a bridge erecting machine as an example, the method specifically includes the following steps.

[0143] (i) The first span of the bridge erecting machine is in place, the two middle support legs 3 are supported on the pier top block, the front auxiliary support leg 2 and the rear auxiliary support leg 4 are detached, and the bridge erecting machine is ready to erect the beam.

[0144] (ii) The first main crane 5 and the second main crane 6 sequentially lift the first segment beam to both sides of the middle support leg 3 in front of the construction site. After initial alignment, the elevation and the aerial posture of the segment block are adjusted. Then the wet joint size is adjusted, and fine alignment is performed. Temporary prestressing tensioning, installation of wet joint template between the T structure and the T structure are completed in sequence, and wet joint is poured. After the wet joint reaches the design strength, the internal permanent prestressing steel strand tensioning is carried out.

[0145] (III) Repeat step (II) to erect the T-structure of the pier where the middle support leg 3 is located in the front of the construction in sequence, and continue until the last pair of segment beams of the middle span T-structure are assembled.

[0146] (iv) After the first T-structure of each section is erected, the first side span segment beam suspension construction is carried out. The specific construction steps are as follows: (1) The segment beam suspension sequence is from the side to the middle of the span, (2) The beam is transported to the position and the suspending rod is installed. The first main crane 5 is controlled to lift the beam. At the same time, the suspending rod and the hanging are used to suspend the segment beam block on the main frame 1. The above steps are repeated until the first span segment beam is completely suspended and assembled. (3) The first main crane 5 is used to adjust the segment beam in three-dimensional space and perform initial alignment. Then epoxy resin is applied. Then precise alignment is performed and temporary prestressing is performed. Then wet joint template is installed and wet joint is poured. Then permanent stress steel strand tensioning of the whole span is performed. (4) After the whole span tensioning is completed, the hanging is unloaded and the hanging is removed.

[0147] (v) The first main crane 5 and the second main crane 6 travel to the vicinity above the two middle support legs 3, respectively, and drive the middle support leg 3 lateral movement mechanism 3c to adjust the main frame of the bridge erecting machine to a suitable position before the span. The specific steps include: (1) The middle support leg lateral movement mechanism 3a drives the whole machine to lateral movement by a certain distance so that the main frame 1 at one middle support leg moves laterally to the target position; (2) Taking the center line of the shifting trolley 3f of one middle support leg at the target position of the main frame 1 as the pivot, the lateral movement mechanism 3a of the other middle support leg continues to carry the main frame 1 laterally to the target position; (3) During the process of the lateral movement mechanism 3a driving the whole machine to lateral movement, the angle between the support leg beam 3e and the main frame 1 will change, and the distance between the two shifting trolleys 3f of a single middle support leg 3 on the support leg beam 3e will change. Therefore, after the lateral movement mechanism 3a of the middle support leg 3 drives the whole machine to lateral movement by a certain distance, the connecting rod 3d between the two shifting trolleys 3a needs to be released, the length of the connecting rod 3g is adjusted, and the shifting trolleys 3a are connected. After the connecting rod 3d is connected, the machine continues to move laterally. This is repeated several times until the target lateral movement is achieved.

[0148] (vi) The first main crane 5, the second main crane 6 and the auxiliary crane 7 move to the tail of the bridge erecting machine and use the longitudinal movement mechanism 3b of the middle support leg 3 to push the main frame forward until the front auxiliary support leg 2 reaches the top of the front pier block. When the bridge erecting machine passes through the hole in the curved section and the front auxiliary support leg 2 is in place on the front pier top or the pier side support, the following steps are required: (1) When the front auxiliary support leg 2 reaches the center of the pier top, release the bolt connection between the upper and lower crossbeams at the lower end of the front auxiliary support leg 2. (2) Drive the lower crossbeam to rotate, so that the lower crossbeam of the front auxiliary support leg 2 is basically parallel to the pier or the pier side support. Reconnect the bolts between the two crossbeams. (3) Continue to move forward to the position and support it on the anchoring longitudinal beam 2j or the pier side support. (4) Effectively anchor the lower crossbeam of the front auxiliary support leg 2 to the anchoring longitudinal beam 2j or the pier side support to prevent it from sliding.

[0149] (vii) Simultaneously support the front auxiliary leg 2 and the rear auxiliary leg 4, detach the rear middle support leg 3, and the first main crane 5 lifts the rear middle support leg 3 to the top of the pier behind the front auxiliary leg 2, supports the rear middle support leg 3, and installs the anchoring device on the top of the pier for the rear middle support leg 3. The first main crane 5 should lift the rear middle support leg 3 through the hole according to the following steps: (1) The front auxiliary crane 2 travels to the front end of the main frame 1, (2) the lifting device of the first main crane 5 is connected to the rear middle support leg 4. (3) The first main crane 5 lifts the rear middle support leg 3 to disengage. (4) The first main crane 5 lifts the rear middle support leg 3 and moves forward to the middle position of the rear span. The first main crane 5 drives the middle support leg 3 to rotate 90° clockwise and then continues to move forward. (5) The first main crane 5 lifts the rear middle support leg 3 to the middle position of the front span and lands and rotates 90° counterclockwise. (6) The first main crane 5 lifts the rear middle support leg 3 and continues to move forward to the top of the pier behind the front auxiliary support leg.

[0150] (viii) After the front auxiliary leg 2 and rear auxiliary leg 4 are removed, the first main crane 5, the second main crane 6 and the auxiliary crane 7 move to the front end of the bridge erecting machine. The main frame is pushed forward by the longitudinal movement mechanism 3b of the middle support leg 3 until the main frame 1 moves forward to the beam erecting position. The bridge erecting machine is ready to pass through the span again.

[0151] (ix) Repeat steps (ii) to (iii) to complete the "T" structure erection of the intermediate pier of the bridge;

[0152] (x) The first main crane 5 and the second main crane 6 are respectively moved to the vicinity above the front and rear middle support legs 3, and the middle support leg 3 is driven to move the transverse mechanism 3c to adjust the main frame 1 of the bridge erecting machine to a suitable position before the hole, in preparation for the final span of the span to pass through the hole. The specific implementation steps are the same as those in step (v).

[0153] (xi) The first main crane 5, the second main crane 6 and the auxiliary crane 7 move to the tail of the bridge erecting machine. The longitudinal movement mechanism 3b of the middle support leg 3 pushes the main frame forward until the front auxiliary support leg 2 reaches the support frame above the pier and is supported on the pier support. The specific implementation steps are the same as in step (vi).

[0154] (12) Use the first main crane 5 to place a segment beam on the top of the side span pier. The first main crane 5 should place a segment beam on the top of the side span pier in place according to the following steps: (1) The front auxiliary crane 2 moves to the front end of the main frame 1, and the first main crane 5 moves forward about 20m. (2) At the same time, use the second main crane 6 to move the rear auxiliary support leg 4 forward to the back of the middle support leg 3, and temporarily suspend it on the lower chord of the main frame 1 with threaded steel bars. (3) Use the second main crane 6 The segmental beam is moved to the span of the two middle legs and placed on the bridge deck. (4) The second main crane 6 returns to the tail of the main frame 1 to continue picking up the beam. The lifting device of the first main crane 5 is reconnected to the segmental beam in the span. (5) The segmental beam is moved to the vicinity of the front span pier using the first main crane 5. (6) The first main crane 5 rotates the segmental beam 90 degrees. (7) The first main crane 5 places the first half of the segmental beam on the top of the pier into place. (8) The segmental beam is temporarily supported and fixed to the pier.

[0155] (xiii) Repeat step (xiv) to install the other segment beam on the pier top and temporarily anchor the two pier top blocks to ensure that they can meet the support requirements of the middle support leg 3.

[0156] (XIV) Support the rear auxiliary leg 4 and detach the rear middle support leg 3. Specifically, follow these steps: (1) The second main crane 6 runs to the tail of the main frame. The second main crane 6 is used to move the rear auxiliary leg 4 backward to a suitable position and bolt it to the lower chord of the main frame to support the rear auxiliary leg 4. (2) Connect the hoisting device of the first main crane 5 and the rear middle support leg 3. The first main crane 5 lifts the rear middle support leg 3 to detach it.

[0157] (XV) The first main crane 5 lifts the rear middle support leg 3 to the top of the pier behind the front auxiliary support leg 2. The specific steps for lifting the rear middle support leg through the hole are the same as the steps for passing through the hole in step (VII). Control the first main crane 5, the second main crane 6 and the auxiliary crane 7 to run to the front end of the bridge erecting machine, and detach the front auxiliary support leg 2 and the rear auxiliary support leg 4. The bridge erecting machine is ready to pass through the hole again.

[0158] (xvi) Using the longitudinal movement mechanism 3b of the middle support leg 3 to push the main frame forward to the beam erection position, construct the last span of the first section, pour the intermediate wet joint, and tension the permanent stress steel strands of the entire span, thus completing the construction of the first section.

[0159] In the description of this invention, it should be understood that the terms "center", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0160] If the terms "first" or "second" are used in this document to define components, those skilled in the art should know that the use of "first" or "second" is merely for the convenience of describing the invention and simplifying the description, and unless otherwise stated, the above terms have no special meaning.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention 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. However, these 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 the present invention.

Claims

1. A construction method for precast segmental beams under complex working conditions, characterized in that, The construction method is based on a segmental assembly bridge erecting machine, which includes a main frame, front auxiliary legs, rear auxiliary legs, two middle legs, a first main crane, a second main crane, and two auxiliary cranes. The first main crane, the second main crane, and the two auxiliary cranes are mounted on the main frame and can move along the main frame. The front auxiliary legs and the rear auxiliary legs are respectively located at the front and rear ends of the main frame; Both of the aforementioned middle support legs include a support assembly and a first lifting assembly. The first lifting assembly is located below the support assembly. The middle support legs are slidably located below the main frame via the support assembly. The support assembly mainly consists of two shifting trolleys, a transverse shifting mechanism, a longitudinal shifting mechanism, and a support leg beam. The shifting trolleys are divided into an upper part and a lower part. The lower part of the shifting trolley is located on the support leg beam, and the upper part of the shifting trolley is connected to the main frame. The upper part of the shifting trolley can rotate along the central axis of the lower part of the shifting trolley. The transverse shifting mechanism drives the shifting trolley to move laterally on the support leg beam, and the longitudinal shifting mechanism pushes the main frame. The front auxiliary outrigger includes a second lifting assembly, a rotating assembly, and a first fixing assembly. The second lifting assembly is located at the front end of the main frame, and the rotating assembly and the fixing assembly are sequentially located below the second lifting assembly. The first fixing assembly can rotate a certain angle on the second lifting assembly through the rotating assembly. The rear auxiliary support leg includes a third lifting component and a second fixing component. The third lifting component is located at the rear end of the main frame, and the second fixing component is located below the third lifting component. The construction method includes the following steps: (i) The first span of the bridge erecting machine is in place, the two middle legs are supported on the pier top block, the front auxiliary legs and the rear auxiliary legs are detached, and the bridge erecting machine is ready to erect the beam. (ii) The first main crane and the second main crane lift the first segment beam to both sides of the middle support leg in front of the construction site in sequence. The initial alignment is adjusted by adjusting the elevation and the aerial posture of the segment block. Then the wet joint size is adjusted, and the fine alignment is carried out. The temporary prestressing tensioning, the installation of the wet joint template between the T structure and the T structure are completed in sequence, and the wet joint is poured. After the wet joint reaches the design strength, the internal permanent prestressing steel strand tensioning is carried out. (iii) Repeat step (ii) and erect the T-structures of the piers where the middle support legs are located in front of the construction in sequence and symmetrically until the last pair of segment beams of the middle span T-structure are assembled. (iv) After the first T-structure of each section is erected, the first side span segment beam suspension construction shall be carried out; (v) The first and second main cranes travel to the vicinity above the two middle support legs respectively, and drive the middle support leg lateral movement mechanism to adjust the main frame of the bridge erecting machine to a suitable position before the span. (vi) The first main crane, the second main crane and the auxiliary crane move to the tail of the bridge erecting machine and use the longitudinal movement mechanism of the middle support leg to push the main frame forward until the front auxiliary support leg reaches the top of the pier block in front. (vii) Simultaneously support the front auxiliary outrigger and the rear auxiliary outrigger, detach the rear middle outrigger, and move the rear middle outrigger of the first main crane to the top of the pier behind the front auxiliary outrigger to support the middle outrigger and install the middle outrigger pier top anchoring device. (viii) After the front and rear auxiliary legs are removed, the first main crane, the second main crane and the auxiliary crane move to the front end of the bridge erecting machine. The main frame is pushed forward by the longitudinal movement mechanism of the middle support leg until the main frame moves forward to the beam erection position. The bridge erecting machine is ready to pass through the span again. (ix) Repeat steps (ii) to (iii) to complete the "T" structure erection of the intermediate pier of the bridge; (x) The first main crane and the second main crane are respectively moved to the vicinity above the front and rear middle support legs, and the middle support leg transverse movement mechanism is driven to adjust the main frame of the bridge erecting machine to a suitable position before the span, in preparation for the final span of the span to pass through the span. (xi) When the first main crane, the second main crane and the auxiliary crane move to the tail of the bridge erecting machine, the longitudinal movement mechanism of the middle support leg pushes the main frame forward until the front auxiliary support leg reaches the support frame above the pier and is supported on the pier support. (xii) Use the first main crane to place a segment beam on the top of the side span pier into place; (xiii) Repeat step (xiv) to install the other segment beam on the pier top and temporarily anchor the two pier top blocks to ensure that they can meet the support requirements of the middle support leg. (xiv) Supporting auxiliary legs after detachment, and the middle support leg after detachment; (xv) The first main crane lifts the middle support leg behind the front auxiliary support leg to the top of the pier. The first main crane, the second main crane and the auxiliary crane move to the front end of the bridge erecting machine, disengage the front auxiliary support leg and the rear auxiliary support leg, and the bridge erecting machine is ready to cross the span again. (xvi) Using the longitudinal movement mechanism of the middle support leg, the main frame is pushed forward to the beam erection position, the last span of the first section is constructed, the intermediate wet joint is poured, and the permanent stress steel strands of the entire span are tensioned, thus completing the construction of the first section.

2. The construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In steps (i), (ii), and (iii), when the bridge erecting machine is performing T-shaped cantilever splicing, the front and rear auxiliary cranes respectively suspend the tensioning platform on both sides of the segment beam to be installed, serving as the operating platform for personnel. When the line is curved, before the first and second main cranes lift the segment beam, the entire machine is moved laterally to a suitable position in advance to avoid moving the entire machine laterally while the first and second main cranes are lifting the segment beam. When the entire machine needs to be moved laterally, the first and second main cranes are positioned above the front and rear middle support legs, respectively.

3. The construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In step (iv), the suspension construction of the first side span segment beam is carried out according to the following steps: (1) The segmental beam is suspended segment by segment from the edge to the mid-span. (2) Transport the beam to the position and install the lifting rod, control the first main crane to lift the beam, and at the same time use the lifting rod and the hanging to suspend the segment beam block on the main frame. Repeat the above steps until the first span segment beam is completely suspended and assembled. (3) The first main crane is used to adjust the segment beam in three-dimensional space and perform initial alignment in sequence, then apply epoxy resin, then perform precise alignment and temporary prestressing tensioning, then install wet joint template and pour wet joint, and then perform permanent stress steel strand tensioning of the whole span. (4) After the entire span is tensioned, the hanging is unloaded and removed.

4. The construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In steps (v) and (x), when the bridge erecting machine crosses a curved section, the transverse movement mechanism inside the middle support leg needs to drive the shifting trolley to carry the main frame through a certain transverse amplitude and control the shifting trolley to rotate a certain angle. The specific steps include: (1) The middle support leg lateral movement mechanism drives the whole machine to laterally move a certain distance so that the main frame at one of the middle support legs moves laterally to the target position; (2) Using the center line of the shifting trolley of one of the middle legs of the main frame reaching the target position as the pivot, drive the lateral shifting mechanism of the other middle leg to continue to carry the main frame to the target position. (3) During the process of the lateral movement mechanism driving the whole machine to move laterally, the angle between the support leg beam and the main frame will change, and the distance between the two shifting trolleys of a single middle support leg on the support leg beam will change. Therefore, after the lateral movement mechanism of the middle support leg drives the whole machine to move laterally a certain distance, the connecting rod between the two shifting trolleys needs to be loosened, the length of the connecting rod is adjusted, and then the shifting trolleys are connected. After the connecting rod is connected, the machine continues to move laterally. This process is repeated several times until the target lateral movement is achieved.

5. A construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In steps (vi) and (xi), when the bridge erecting machine passes through the arch on a curved section and the front auxiliary outrigger is positioned on the support on the top of the pier or beside the pier, the following steps need to be followed: (1) When the front auxiliary outrigger reaches the center of the pier top, release the bolt connection between the upper and lower crossbeams at the lower end of the front auxiliary outrigger; (2) Drive the lower crossbeam to rotate, so that the lower crossbeam of the front auxiliary leg is basically parallel to the pier or the pier-side support, and reconnect the bolts between the two crossbeams; (3) Continue forward to the designated position and support the anchor beam or the pier support; (4) Effectively anchor the lower crossbeam of the front auxiliary leg to the anchoring longitudinal beam or the side of the pier to prevent it from sliding.

6. A construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In steps (vii) and (xv), the passage through the middle support leg behind the first main crane should be performed according to the following steps: (1) The front auxiliary crane travels to the front end of the main frame; (2) Connect the lifting device of the first main crane to the rear middle support leg, and lift the rear middle support leg of the first main crane to detach it; (3) The first main crane lifts the rear middle support leg and moves forward to the middle position of the rear span. The first main crane drives the middle support leg to rotate 90 degrees clockwise, and then continues to move forward. (4) The first main crane lifts the rear middle support leg to the middle position of the front span and descends and rotates 90 degrees counterclockwise; (5) The first main crane lifts the middle support leg and continues to move forward to the top of the pier behind the front auxiliary support leg.

7. A construction method for precast segmental beams under complex working conditions according to claim 6, characterized in that, During the process of hoisting the middle support leg through the hole of the first main crane: (1) During the process of the first main crane reversing the outrigger, the lifting device rotation mechanism of the main crane has two 90° rotation movements, and the two rotations are in opposite directions; (2) When the middle support leg of the first main crane is detached and cannot be balanced, the two shifting trolleys of the middle support leg are adjusted to serve as weights to balance it. Then the position of the shifting trolleys is fixed and the middle support leg is continued to be hoisted forward.

8. A construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In step (twelfth), the first main crane needs to place a segmental beam on the top of the side span pier into place according to the following steps: (1) The front auxiliary crane moves to the front end of the main frame, and the first main crane moves forward 20m; (2) At the same time, the second main crane is used to move the rear auxiliary leg forward to the rear of the middle leg, and temporarily hang it on the lower chord of the main frame with threaded steel bars; (3) Use the second main crane to move the segmental beam to the two middle support spans and place it on the bridge deck; (4) The second main crane returns to the tail of the main frame to continue picking up beams, and the lifting device of the first main crane is reconnected to the segmental beams in the span; (5) Use the first main crane to move the segmental beam to the vicinity of the front span pier; (6) The first main crane rotates the segmental beam by 90 degrees; (7) The first main crane places the first half segment beam on the pier top into place; (8) Temporarily support and fix the segmental beams to the piers.

9. A construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, In step (fourteen), the method of supporting the auxiliary outrigger and detaching the middle outrigger is as follows: (1) When the second main crane moves to the end of the main frame, the second main crane is used to move the rear auxiliary leg backward to a suitable position and bolt it to the lower chord of the main frame to support the rear auxiliary leg; (2) The hoisting device that connects the first main crane hoist and the rear middle support leg, and the first main crane lifts the rear middle support leg to detach.

10. A construction method for precast segmental beams under complex working conditions according to claim 1, characterized in that, The first main crane and the second main crane each include two first traveling mechanisms, a hoisting mechanism and a lifting beam assembly. The two first traveling mechanisms are driven by pin gears. The first main crane and the second main crane move along the top of the main frame through the first traveling mechanisms. The hoisting winch mechanism is connected to the lifting beam assembly via a wire rope. The lifting beam assembly is equipped with a three-dimensional adjustment device for adjusting the angle of the lifting beam assembly. The lifting beam assembly is also equipped with components for hoisting the front auxiliary outrigger, the rear auxiliary outrigger, and the middle outrigger.

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