Construction method of short roadbed beam of small-section tunnel portal

Abstract

The application relates to a small-section tunnel portal short subgrade frame beam construction method, and relates to the technical field of frame beam construction, which comprises the following construction steps: detection: the working height of a bridge erecting machine is Q, the tunnel clearance height H is measured, and whether H>=Q is detected; if yes, erecting: the bridge erecting machine is positioned to perform frame beam construction; if not, adjusting: the tunnel portal track rail surface elevation or / and the working height of the bridge erecting machine is lowered until the erecting process is performed after the condition is met. The application detects the tunnel clearance height to obtain data H, so as to judge whether H>=Q; when the condition is met, the bridge erecting machine is positioned to perform frame beam construction; when the condition is not met, adjustment is performed, one of or both of the tunnel portal track rail surface height and the working height of the bridge erecting machine are lowered until the condition is met, the convenience during adjustment is improved, and therefore the frame beam construction efficiency is improved.

Description

Technical Field

[0001] This application relates to the technical field of bridge erection construction, and in particular to a method for bridge erection construction of short roadbeds at small cross-section tunnel entrances. Background Technology

[0002] Bridge erecting machines are commonly used equipment in bridge girder construction. They are used to place prefabricated bridge girders onto prefabricated bridge piers. Bridge erecting machines belong to the category of cranes, and their main function is to lift the bridge girders and move them (or longitudinally move them) on the bridge deck to transport them to their positions before lowering them down.

[0003] In the construction of railways in mountainous areas of my country, due to the influence of topography and geological conditions, bridges and tunnels account for a large proportion of the line. In some sections, bridges and tunnels are densely distributed in groups. The tunnel entrances are mostly "V"-shaped valleys with steep slopes. The bridges and tunnels are connected, but the roadbed at the tunnel entrance is too short or the bridge abutments are arranged inside the tunnel. However, there are requirements for the construction height of the bridge erecting machine. The height of the tunnel is not known during the operation of the bridge erecting machine, which makes it easy for the bridge erecting machine to collide or even fail to carry out construction. Therefore, the construction efficiency of bridge erection is greatly reduced. Summary of the Invention

[0004] To improve the efficiency of bridge girder erection, this application provides a method for bridge girder erection at short roadbeds near small-section tunnel entrances.

[0005] This application provides a method for constructing bridge erection on short roadbeds at the entrance of small-section tunnels, which adopts the following technical solution:

[0006] A method for constructing bridges for short roadbeds at the entrance of small-section tunnels includes the following construction steps:

[0007] Inspection: The working height of the bridge erecting machine is Q. The tunnel clearance height H is measured to check whether H≥Q is satisfied.

[0008] Satisfaction, erection: The bridge erecting machine is positioned to carry out the bridge girder erection construction;

[0009] If not met, adjust: lower the elevation of the track surface at the tunnel entrance and / or the working height of the bridge erecting machine until the requirements are met before proceeding with the erection process.

[0010] By adopting the above technical solution, the tunnel clearance height is first detected to obtain data H, and the working height of the bridge erecting machine is a known height Q. This is used to determine whether H≥Q is satisfied. When satisfied, no adjustment is needed, and the bridge erecting machine is positioned to carry out beam erection. When not satisfied, adjustments are made by either reducing the height of the track surface at the tunnel entrance or reducing the working height of the bridge erecting machine, or by doing both simultaneously, until the condition is met. This improves the convenience of adjustment and thus improves the efficiency of beam erection.

[0011] Optionally, when the track is ballasted, the track bed and track height can be adjusted by adjusting the amount of ballast, thereby adjusting the track surface elevation at the tunnel entrance.

[0012] By adopting the above technical solution, the ballasted track is made of crushed stone, so the height of the ballasted track is easy to adjust. This allows for adjustment of the amount of ballast to achieve adjustment of the track bed and track height, thereby improving the convenience of adjustment and increasing the construction efficiency of beam erection.

[0013] Optionally, when the track is a ballastless track, the adjustment method is as follows:

[0014] In sections with ballastless track, a section of track is reserved before construction. Then, temporary self-made track panels are installed to create a bridge-building passage for the bridge-building machine to pass through. The track is then constructed after the bridge beams are erected, thereby increasing the tunnel clearance height.

[0015] First, the steel bars for the retaining wall are tied and poured without concrete. Then, the steel bars are temporarily bent downwards through a bending mechanism to reduce the height of the bridge. After the bridge beam is erected, the bending mechanism is activated to straighten the steel bars, and then concrete is poured to form the retaining wall. At the same time, the bridge erecting machine is connected to the bridge through a hoisting mechanism. The hoisting mechanism is adjusted in length to adapt to the reduced height of the bridge, thereby reducing the working height of the bridge erecting machine.

[0016] By adopting the above technical solution, the ballastless track is made of concrete. Therefore, the height of the ballastless track is not easy to adjust. Therefore, the track within the movement range of the bridge erecting machine is not constructed first. Instead, a self-made track panel is installed to build a bridge erecting channel for the bridge erecting machine to pass through. The self-made track panel only needs to support the bridge erecting machine. Therefore, the height of the track panel can be reduced, thereby increasing the tunnel clearance height. After the beam is erected, the track is laid.

[0017] First, the reinforcing steel for the retaining wall is tied and poured without concrete. Then, the reinforcing steel is temporarily bent downwards using a bending mechanism, thereby reducing the height of the bridge. At the same time, the hoisting mechanism is adjusted in length to accommodate the reduced bridge height, thus lowering the working height required for the bridge erecting machine. Therefore, the height can be reduced during the installation of the bridge erecting machine. The bridge erecting machine is started to erect the beams. After the beams are erected, the bending mechanism is activated to straighten the bent reinforcing steel. Then, concrete is poured to form the retaining wall, thereby reducing the working height of the bridge erecting machine. Therefore, both adjustments are made simultaneously, which improves the convenience of adjustment and the construction efficiency of beam erection.

[0018] Optionally, the track panel includes:

[0019] Multiple pads are placed on the ballastless track bed and arranged along the moving direction of the bridge erecting machine;

[0020] Two support rails are fixedly installed on multiple pads by fasteners and are used for the passage of the bridge erecting machine.

[0021] By adopting the above technical solution, multiple pads are placed on the ballastless track, and then two support tracks are fixedly connected to the multiple pads through fasteners, thereby enabling the bridge erecting machine to support and pass through.

[0022] Optionally, the bending mechanism includes:

[0023] A first sleeve and a second sleeve are both sleeved on the reinforcing bar and their ends, which are close to each other, are rotatably connected together. The first sleeve is located below the second sleeve.

[0024] A clamp is provided on the bottom end of the first sleeve and is used to position the first sleeve and connect the reinforcing bar to the first sleeve. The clamp is positioned against the beam.

[0025] The telescopic component is rotatably mounted on the first sleeve and rotatably connected to the second sleeve, and is used to drive the second sleeve and the reinforcing bar to rotate simultaneously to achieve bending.

[0026] By adopting the above technical solution, the first sleeve and the second sleeve are fitted onto the steel bar, the clamp is pushed against the beam for positioning, and then the clamp positions the first sleeve so that the first sleeve is connected to the steel bar. Then the telescopic component starts to retract. Since the clamp is against the beam, the first sleeve cannot rotate, so the second sleeve rotates. The rotation of the second sleeve realizes the bending of the steel bar.

[0027] The beam and bending mechanism are transported together. After the beam is erected, the telescopic component extends and drives the second sleeve to rotate, straightening the steel bars. Then the clamps are unlocked, and the bending mechanism can be removed. Then concrete is poured to form a retaining wall, which improves the convenience of bending and straightening the steel bars, thus improving the construction efficiency of the beam erection.

[0028] Optionally, a tapered clamping surface is provided on the inner sidewall of the bottom end of the first sleeve, and the clamp includes:

[0029] The clamp is sleeved on the reinforcing bar and has multiple evenly spaced grooves. The clamp is elastic and has a spaced surface that fits into the clamping surface.

[0030] A clamping sleeve is threaded onto the outer wall of the first sleeve and presses against the clamping head to push the clamping head to clamp the reinforcing bar.

[0031] By adopting the above technical solution, the first and second sleeves, the clamp, and the clamping sleeve are all fitted onto the reinforcing bar. The sleeve is pushed downward so that the clamping sleeve abuts against the beam. Then, the clamping sleeve is rotated, and the rotation of the clamping sleeve pushes the clamp to clamp onto the reinforcing bar, thereby fixing the first sleeve to the reinforcing bar. Then, the telescopic component is activated, which can pull the second sleeve and the reinforcing bar to rotate, thereby achieving the bending of the reinforcing bar. After the telescopic component is activated, it drives the second sleeve and the reinforcing bar to rotate, thereby straightening the reinforcing bar. Then, the clamping sleeve is twisted away from the first sleeve, and the bending mechanism can be removed. This improves the convenience of operating the bending mechanism and increases the construction efficiency of the cap beam.

[0032] Optionally, the hoisting mechanism includes:

[0033] A lifting device that moves vertically on the bridge erecting machine and is used to lift the bridge beam;

[0034] An adjustment assembly, which is mounted on the bridge erecting machine and used to adjust the position of the spreader;

[0035] A locking component is provided on the bridge erecting machine and is used to lock the position of the spreader.

[0036] By adopting the above technical solution, the adjustment component is used to adjust the vertical position of the lifting device, while the locking component is used to lock the position of the lifting device. This allows the position of the lifting device to be adjusted as needed to accommodate the lifting of beams at different heights. It also improves the convenience of adjustment and increases the construction efficiency of the cap beam.

[0037] Optionally, the adjustment component includes:

[0038] A collection tray, which is rotatably mounted on the bridge erecting machine;

[0039] A steel wire rope, one end of which is mounted on the bridge erecting machine and passes through the lifting device before being wound up onto a collection tray;

[0040] A collecting motor is mounted on the bridge erecting machine and its output shaft is connected to the collecting disc.

[0041] By adopting the above technical solution, when adjustment is required, the locking component is unlocked, and then the collecting motor is started to drive the collecting disc to rotate. The rotating collecting disc is used to wind up or unwind the wire rope, so the wire rope moves to adjust the position of the lifting device. After the adjustment is completed, the locking group is started to position the lifting device, thereby realizing the adjustment of the lifting device position.

[0042] Optionally, the locking component includes:

[0043] A toothed ring, wherein the toothed ring is disposed on a collection tray;

[0044] A movable gear disc, which is slidably mounted on the bridge erecting machine;

[0045] A driving component, which is mounted on the bridge erecting machine and is used to drive the moving gear plate to move;

[0046] A fixed block and a clamping block are provided. The fixed block is installed on the bridge erecting machine. The clamping block is connected to the drive component and moves together with the moving gear plate. The wire rope passes between the fixed block and the clamping block. When the moving gear plate is engaged with the gear ring for positioning, the clamping block moves close to the fixed block and the clamping block and the fixed block cooperate to clamp the wire rope.

[0047] By adopting the above technical solution, when unlocking is required, the drive unit is activated, causing the moving gear disc to move away from and disengage from the gear ring. At the same time, the clamping block is also moved away from the fixed block, so the collecting disc can rotate freely, and the wire rope located between the fixed block and the clamping block can also move freely. When locking is required, the drive unit is activated, causing the moving gear disc to move closer and engage with the gear ring. The clamping block moves closer to the fixed block and cooperates with the fixed block to clamp the wire rope, thereby achieving the positioning of the wire rope and the lifting device. This improves the stability of the lifting device when lifting the beam, and the simple and stable structure improves the construction efficiency of the cap beam.

[0048] Optionally, the sidewalls of the fixing block and the clamping block on opposite sides are provided with clamping surfaces that fit against the wire rope.

[0049] By adopting the above technical solution, the clamping effect of the wire rope is improved, and the stability during beam hoisting is enhanced.

[0050] In summary, this application includes at least one of the following beneficial technical effects:

[0051] The data H is obtained by detecting the tunnel clearance height to determine whether H≥Q is satisfied. When satisfied, the bridge erecting machine is positioned to carry out the bridge erection construction. When not satisfied, adjustments are made by reducing the height of the track surface at the tunnel entrance and the working height of the bridge erecting machine, or by both methods simultaneously, until the condition is met. This improves the convenience of adjustment and thus improves the efficiency of bridge erection construction. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of this application;

[0053] Figure 2 yes Figure 1 Enlarged diagram of section A in the middle;

[0054] Figure 3 This is a schematic diagram of the bending mechanism in this application;

[0055] Figure 4 This is a partial exploded view of the bending mechanism in this application;

[0056] Figure 5 This is a structural schematic diagram of the hoisting mechanism in this application.

[0057] Reference numerals: 1. Bridge erecting machine; 12. Reinforcing bar; 13. Beam; 2. Rail panel; 21. Pad; 22. Support rail; 3. Bending mechanism; 31. First sleeve; 32. Second sleeve; 33. Telescopic component; 34. Rotating shaft; 35. Clamping surface; 4. Clamp; 41. Chuck; 42. Clamping sleeve; 43. Alternating surface; 44. Alternating groove; 5. Lifting mechanism; 51. Lifting tool; 6. Adjusting component; 61. Collection tray; 62. Wire rope; 63. Collection motor; 64. Rotating wheel; 7. Locking component; 71. Gear ring; 72. Moving gear disc; 73. Driving component; 74. Fixing block; 75. Clamping block; 76. Connecting rod; 77. Clamping surface. Detailed Implementation

[0058] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0059] This application discloses a method for constructing bridges for short roadbeds at the entrance of small-section tunnels.

[0060] Reference Figure 1 The construction method for short roadbed beam erection at the entrance of a small-section tunnel includes the following steps:

[0061] Inspection: The working height of the bridge erecting machine 1 is Q. The tunnel clearance height H is measured. H is the distance between the track surface and the top of the tunnel. The track has been partially laid in the tunnel. H is measured based on the laid track. Check whether H≥Q is satisfied.

[0062] Satisfaction, erection: Satisfaction means that when the bridge erecting machine 1 is running on the track, there is still a gap between the top of the bridge erecting machine 1 and the top of the tunnel, indicating that the bridge erecting machine 1 can operate normally. Therefore, the track in the tunnel can be laid completely. Then the bridge erecting machine 1 is in place and moves the beam 13 to carry out the beam erection construction. The direction of movement of the bridge erecting machine 1 is parallel to the length direction of the beam 13. The structure of the bridge erecting machine 1 is the existing technology structure, which will not be described in detail here.

[0063] If not satisfied, adjust: lower the elevation of the track surface at the tunnel entrance and / or the working height of the bridge erecting machine 1 until the requirements are met before proceeding with the erection process.

[0064] When the track is a ballasted track, which is a track laid with crushed stone, the adjustment method is to adjust the amount of ballast to adjust the height of the track bed and the track. That is, by adjusting the thickness of the crushed stone, and then laying the track on the crushed stone, the height of the track is reduced, thereby adjusting the track surface elevation at the tunnel entrance until the conditions are met.

[0065] Reference Figure 1 and Figure 2 When the track is a ballastless track, the adjustment method is as follows:

[0066] In the ballastless track section, a section of track is reserved and not constructed. Then, a temporary self-made track panel 2 is installed to form a bridge erection channel for the bridge erection machine 1 to pass through. The height of the track panel 2 is lower than the height of the track to be laid. The track to be laid will be constructed after the bridge erection is completed. This increases the tunnel clearance height, that is, the space height above the track panel 2.

[0067] First, the reinforcing bars 12 for the retaining wall are tied and poured without concrete. Then, the bending mechanism 3 is installed on the reinforcing bars 12. Next, the bending mechanism 3 is activated to bend the reinforcing bars 12, thereby temporarily bending the reinforcing bars 12 and reducing the height of the beam 13. At the same time, the bridge erecting machine 1 is connected to the beam 13 through the hoisting mechanism 5. The hoisting mechanism 5 is adjusted in height to adapt to the connection with the beam 13 after the height is reduced. Therefore, the bridge erecting machine 1 can be lowered in height during installation, thereby reducing the working height of the bridge erecting machine 1.

[0068] The retaining wall is located on both sides of the beam 13. The steel bars 12 of the retaining wall constructed first are all in a vertical state. The steel bars 12 are arranged in multiple rows along the length of the beam 13, and each row of steel bars 12 is arranged in multiple rows along the length of the beam 13. Then, the steel bars are bent and the beam is erected. After the beam is erected, the steel bars 12 are straightened and then concrete is poured on the steel bars 12 to form the retaining wall. If horizontal steel bars 12 need to be fixed on the vertical steel bars 12, multiple horizontal steel bars 12 are fixed on the multiple vertical steel bars 12 after straightening. Finally, concrete is poured on the steel bars 12 to form the retaining wall.

[0069] The height is adjusted using both methods simultaneously until the conditions are met. Once the conditions are met, the erection process begins. The bridge erecting machine 1 moves into position to erect the beam. After the beam is erected, the bending mechanism 3 is activated to straighten the reinforcing bar 12. Then, the bending mechanism 3 is removed, and concrete can be poured onto the reinforcing bar 12 to form a retaining wall.

[0070] Reference Figure 1 and Figure 2 The track panel 2 includes multiple base plates 21 and two support rails 22. The multiple base plates 21 are placed on the ballastless track bed and are spaced apart along the moving direction of the bridge erecting machine 1. At the same time, the length direction of the base plates 21 is perpendicular to the moving direction of the bridge erecting machine 1. The length direction of the support rails 22 is perpendicular to the length direction of the base plates 21. The two support rails 22 are placed on both ends of the multiple base plates 21 respectively. At the same time, each support rail 22 is connected together by multiple connecting rails connected end to end. The connecting rails are fixedly connected to the base plates 21 by fasteners, thereby forming a bridge erecting channel for the bridge erecting machine 1 to pass through.

[0071] Reference Figure 1 and Figure 3 The bending mechanism 3 includes a first sleeve 31, a second sleeve 32, a clamp 4, and a telescopic component 33. The axes of the first sleeve 31 and the second sleeve 32 coincide and are both slidably sleeved on the reinforcing bars 12. The first sleeve 31 is located below the second sleeve 32. The top end of the first sleeve 31 and the bottom end of the second sleeve 32 are rotatably connected together by a rotating shaft 34. The rotating shaft 34 is located on the side of the first sleeve 31 and the second sleeve 32 closer to the inside of the beam 13, and the rotating shafts 34 on the two rows of reinforcing bars 12 are arranged opposite to each other. At the same time, the inner diameters of the first sleeve 31 and the second sleeve 32 are the same and greater than or equal to the diameter of the reinforcing bars 12.

[0072] The clamp 4 is set on the bottom end of the first sleeve 31 and is used to position the first sleeve 31 so that the reinforcing bar 12 is connected to the first sleeve 31. At the same time, when the first sleeve 31 and the second sleeve 32 are fitted onto the reinforcing bar 12, the clamp 4 is positioned against the upper surface of the beam 13.

[0073] Reference Figure 3 and Figure 4 The first sleeve 31 has a conical clamping surface 35 coaxially formed on the inner side wall of the bottom end, and the bottom diameter of the clamping surface 35 is larger than the top diameter; the clamp 4 includes a chuck 41 and a clamping sleeve 42. The chuck 41 is sleeved on the reinforcing bar 12, and the inner diameter of the chuck 41 is the same as the inner diameter of the first sleeve 31. At the same time, the outer side wall of the chuck 41 has a clearance surface 43 that fits with the clamping surface 35. The chuck 41 is elastic and has multiple clearance grooves 44 arranged in a circular array around the axis of the first sleeve 31 at the bottom end. The clearance grooves 44 connect the clearance surface 43 and the inner side wall of the chuck 41 and extend upward to the top of the chuck 41.

[0074] Reference Figure 1 and Figure 4 The clamp 42 is threaded to the outer wall of the bottom end of the first sleeve 31. Twisting the clamp 42 pushes the clamp 41 upward, so that the clearance surface 43 and the clamping surface 35 are tightly attached together. Under the upward thrust of the clamp 42, the clamp 41 clamps the steel bar 12, thereby connecting the first sleeve 31 and the steel bar 12 together for positioning. At the same time, the bottom end of the clamp 42 abuts against the upper surface of the beam 13 for positioning.

[0075] The telescopic component 33 can be an electric actuator or a hydraulic cylinder. One end of the telescopic component 33 is rotatably mounted on the outer wall of the first sleeve 31, and the piston rod of the telescopic component 33 is rotatably connected to the side wall of the second sleeve 32. The telescopic component 33 is located on the side of the first sleeve 31 and the second sleeve 32 closest to the rotating shaft 34. The clamp 42, clamp 41, first sleeve 31, and second sleeve 32 are sequentially fitted onto the reinforcing bar 12. Then, the first sleeve 31 is pushed downwards to move it, causing the clamp 42 to abut against the beam 13 for positioning. Then, it is tightened... The moving clamp 42 causes the first sleeve 31 to move downward, so that the clamp 41 clamps onto the reinforcing bar 12, thereby connecting the first sleeve 31 and the reinforcing bar 12 together. This allows the bending mechanism 3 to be installed onto the reinforcing bar 12. Then, multiple bending mechanisms 3 are installed onto multiple reinforcing bars 12 respectively. Then, the piston rods of multiple telescopic components 33 retract simultaneously, pulling the top of the second sleeve 32 downward to rotate. The second sleeve 32 rotates and bends the reinforcing bar 12, thereby achieving the simultaneous bending of multiple reinforcing bars 12.

[0076] The beam body 13 and multiple bending mechanisms 3 are transported simultaneously for subsequent beam erection. After the beam erection is completed, the piston rods of multiple telescopic components 33 extend simultaneously to push multiple reinforcing bars 12 to rotate, thereby straightening the multiple reinforcing bars 12. Then, the clamp 42 is turned to make the clamp 41 release the reinforcing bars 12, and then the bending mechanism 3 can be removed, thus realizing the bending and straightening of the reinforcing bars 12, improving the convenience of bending and straightening the reinforcing bars 12, and improving the construction efficiency of beam erection.

[0077] Reference Figure 1 and Figure 5 Multiple hoisting mechanisms 5 are spaced apart along the length of the beam 13. The hoisting mechanism 5 includes a hoisting device 51, an adjusting component 6, and a locking component 7. The hoisting device 51 moves vertically on the bridge erecting machine 1 and is used to hoist the beam 13. In the prior art, steel ropes are fixed to the beam 13 and then connected to the hoisting device 51. The adjusting component 6 is set on the bridge erecting machine 1 and is used to adjust the position of the hoisting device 51. The adjusting component 6 includes a collecting tray 61, a wire rope 62, and a collecting motor 63. The collecting tray 61 is rotatably mounted on the bridge erecting machine 1. The collecting tray 61 is in a horizontal state and its axis is perpendicular to the length of the beam 13.

[0078] A pulley 64 is rotatably mounted on the lifting device 51. One end of a wire rope 62 is fixedly mounted on the bridge erecting machine 1 located on one side of the collecting tray 61. The wire rope 62 passes through the lifting device 51 and is then fixedly mounted on the collecting tray 61. The wire rope 62 is wound onto the collecting tray 61 and presses against the pulley 64. When the wire rope 62 moves, it pulls the pulley 64 to rotate. A collecting motor 63 is fixedly mounted on the bridge erecting machine 1, and the output shaft of the collecting motor 63 is coaxially connected to the collecting tray 61. When the collecting motor 63 starts, it drives the collecting tray 61 to rotate. The rotation of the collecting tray 61 releases or collects the wire rope 62, thereby adjusting the position of the lifting device 51 to adapt to beams 13 of different heights. Therefore, the height can be adjusted during the installation of the bridge erecting machine 1. When the height of the beam 13 decreases, the installation height of the bridge erecting machine 1 can be lowered accordingly, thus reducing the working height of the bridge erecting machine 1.

[0079] The locking component 7 is installed on the bridge erecting machine 1 and is used to position the lifting device 51. The locking component 7 includes a toothed ring 71, a movable toothed disc 72, a driving component 73, a fixing block 74, and a clamping block 75. The toothed ring 71 is coaxially fixedly installed on the end of the collecting tray 61 away from the collecting motor 63, and multiple toothed grooves are spaced around the axis of the collecting tray 61. The movable toothed disc 72 is slidably installed on the bridge erecting machine 1 along the axis of the collecting tray 61. The driving component 73 can be an electric push rod or a hydraulic cylinder. The piston rod of the driving component 73 is connected to the movable toothed disc 72. When the driving component 73 is activated, it drives the movable toothed disc 72 to approach and engage with the toothed ring 71, thereby positioning the collecting tray 61.

[0080] The fixing block 74 and the clamping block 75 are located on both sides of the wire rope 62 and below the collecting tray 61. The fixing block 74 is fixedly installed on the bridge erecting machine 1, while the clamping block 75 is connected to the piston rod of the driving component 73 through the connecting rod 76. At the same time, clamping surfaces 77 are provided on the side walls of the opposite side of the fixing block 74 and the clamping block 75. When the moving toothed disc 72 meshes with the toothed ring 71, the fixing block 74 and the clamping block 75 cooperate to clamp the wire rope 62, and the two clamping surfaces 77 are in close contact with the wire rope 62 for positioning. When the moving toothed disc 72 moves away from the toothed ring 71 and disengages from the toothed ring 71, the clamping block 75 moves away from the fixing block 74, thereby enabling the collecting tray 61 to rotate freely and the wire rope 62 to move freely.

[0081] The working principle of this application embodiment is as follows:

[0082] The track has been partially laid in the tunnel. First, determine the working height of the bridge erecting machine 1 as Q, then measure the tunnel's clearance height H, and check if H≥Q is satisfied. If satisfied, the track laying is completed, and the bridge erecting machine 1 can be directly positioned for beam erection. If not satisfied, adjustments are made. When the track is ballasted, the amount of ballast is directly adjusted to adjust the track surface elevation at the tunnel entrance until the conditions are met. Then, the track is laid, and beam erection is carried out.

[0083] When the track is ballastless, a self-made track panel 2 is installed on the track bed to form a bridge erection channel for the bridge erecting machine 1 to pass through. The track is then installed on the track bed after the beam erection is completed. The reinforcing steel bars 12 of the retaining wall are not poured with concrete first. Instead, they are bent using a bending mechanism 3, which reduces the height of the beam 13. The hoisting mechanism 5 is also lowered to accommodate the connection with the beam 13 after the height reduction. Therefore, the bridge erecting machine 1 can be lowered during installation, thereby reducing the working height of the bridge erecting machine 1. Adjustments are made by one or both of the above methods until the conditions are met, and then the beam is erected. After the beam erection is completed, the bending mechanism 3 straightens the reinforcing steel bars 12. After the bending mechanism 3 is removed, concrete is poured to form the retaining wall, thereby improving the construction efficiency of the beam erection.

[0084] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for constructing bridges for short roadbeds at the entrance of small-section tunnels, characterized in that: The construction steps include the following: Inspection: The working height of the bridge erecting machine (1) is Q. The tunnel clearance height H is measured to check whether H≥Q is satisfied. Satisfaction, erection: The bridge erecting machine (1) is in place to carry out the bridge erection construction; If not satisfied, adjust: lower the elevation of the track surface at the tunnel entrance and / or the working height of the bridge erecting machine (1) until the requirements are met, and then proceed with the erection process; When the track is ballasted, the adjustment method is to adjust the amount of ballast to adjust the height of the track bed and the track, thereby adjusting the track surface elevation at the tunnel entrance; Alternatively, when the track is a ballastless track, the adjustment method is as follows: In the ballastless track section, a section of track is reserved and not constructed. Then, a temporary self-made track panel (2) is installed to lay the bridge erection channel for the bridge erection machine (1) to pass through. The track is constructed after the beam erection is completed, thereby increasing the tunnel clearance height. First, the steel bars (12) of the retaining wall are tied without pouring concrete. Then, the steel bars (12) are temporarily bent downward through the bending mechanism (3) to reduce the height of the beam (13). At the same time, the bridge erecting machine (1) is connected to the beam (13) through the hoisting mechanism (5). The hoisting mechanism (5) is adjusted in height to adapt to the connection with the beam (13) after the height is reduced, thereby reducing the working height of the bridge erecting machine (1). After the conditions are met, the erection process is carried out. The bridge erecting machine (1) moves into position to erect the beam. After the beam is erected, the bending mechanism (3) is started to straighten the steel bar (12). Then the bending mechanism (3) is removed and concrete is poured to form a retaining wall.

2. The construction method of a small cross-section tunnel portal short subgrade beam frame beam according to claim 1, characterized in that: The track panel (2) includes: Multiple pads (21) are placed on the ballastless track bed and arranged along the moving direction of the bridge erecting machine (1); Two support rails (22) are fixedly installed on multiple pads (21) by fasteners and are used for the passage of the bridge erecting machine (1).

3. The method for constructing a short-section tunnel entrance bridge girder as described in claim 1, characterized in that: The bending mechanism (3) includes: The first sleeve (31) and the second sleeve (32) are both sleeved on the steel bar (12) and their ends are rotatably connected together. The first sleeve (31) is located below the second sleeve (32). The clamp (4) is set on the bottom end of the first sleeve (31) and is used to position the first sleeve (31) and connect the reinforcing bar (12) to the first sleeve (31). The clamp (4) is positioned against the beam (13). The telescopic component (33) is rotatably mounted on the first sleeve (31) and rotatably connected to the second sleeve (32), and is used to drive the second sleeve (32) and the reinforcing bar (12) to rotate simultaneously to achieve bending.

4. The method for constructing a short-section tunnel entrance bridge girder as described in claim 3, characterized in that: The first sleeve (31) has a tapered clamping surface (35) on the inner side wall at the bottom end, and the clamp (4) includes: The clamp (41) is sleeved on the reinforcing bar (12) and has a plurality of clearance grooves (44) evenly provided. The clamp (41) is elastic and has clearance surfaces (43) that fit with the clamping surface (35). The clamp (42) is threaded to the outer wall of the first sleeve (31) and presses against the clamp (41) and is used to push the clamp (41) to clamp the reinforcing bar (12).

5. The method for constructing a short-section tunnel entrance bridge girder as described in claim 1, characterized in that: The hoisting mechanism (5) includes: The lifting device (51) moves vertically on the bridge erecting machine (1) and is used to lift the beam (13). Adjustment component (6), which is mounted on the bridge erecting machine (1) and is used to adjust the position of the lifting device (51); Locking component (7), which is disposed on the bridge erecting machine (1) and is used to lock the position of the lifting device (51).

6. The method for constructing a short-section tunnel entrance bridge girder as described in claim 5, characterized in that: The adjustment component (6) includes: A collection tray (61) is rotatably mounted on the bridge erecting machine (1); A steel wire rope (62), one end of which is set on the bridge erecting machine (1) and passes through the lifting device (51) before being wound onto the collection tray (61); A collecting motor (63) is mounted on the bridge erecting machine (1) and its output shaft is connected to the collecting disc (61).

7. The method for constructing a short-section tunnel entrance bridge girder as described in claim 6, characterized in that: The locking component (7) includes: A toothed ring (71) is disposed on a collection tray (61); A movable gear disc (72) is slidably mounted on the bridge erecting machine (1); A drive unit (73) is mounted on the bridge erecting machine (1) and is used to drive the moving gear plate (72) to move; A fixing block (74) and a clamping block (75) are provided. The fixing block (74) is mounted on the bridge erecting machine (1). The clamping block (75) is connected to the drive unit (73) and moves together with the moving gear plate (72). The wire rope (62) passes between the fixing block (74) and the clamping block (75). When the moving gear plate (72) is engaged with the gear ring (71) for positioning, the clamping block (75) moves close to the fixing block (74) and the clamping block (75) and the fixing block (74) cooperate to clamp the wire rope (62).

8. The method for constructing a short-section tunnel entrance bridge girder as described in claim 7, characterized in that: The fixing block (74) and the clamping block (75) are both provided with clamping surfaces (77) that fit against the wire rope (62) on the opposite side wall.

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