Large-span large-section single-box single-chamber cast-in-situ box girder hanging basket cantilever casting system and construction method

Abstract

The present application relates to a kind of large-span large section single-box single-chamber cast-in-place box girder hanging basket cantilever pouring system and construction method, comprising the following steps: installing track beam on the concrete box girder 0-1 block that has been poured, installing formwork support system, outer formwork system installation, telescopic inner formwork system installation, carry out the pouring operation of concrete box girder.The beneficial effects of the present application are: truss system and formwork support system move independently, and truss system presents inverted trapezoidal structure, formwork support system does not affect the forward movement of truss system;When truss system moves forward, formwork support system and the load thereon are supported on the better beam section, after truss system moves forward and is anchored, formwork support system is moved forward again, improve the safety of hanging basket walking stage;Outer formwork system, telescopic inner formwork system are supported on the inner form of formwork support system Lower longitudinal beam, follow formwork support system and move forward synchronously, improve the safety and efficiency of formwork movement.

Description

Technical Field

[0001] This invention belongs to the field of cantilever construction of cast-in-place concrete box girders, and particularly relates to a hanging basket cantilever system and construction method for large-span, large-section single-box single-cell cast-in-place box girders. Background Technology

[0002] When constructing cast-in-place concrete box girders, the cantilever formwork method is often adopted. This method not only ensures the connection strength between segments but also reduces the impact of bridge construction on existing road traffic and navigation. However, due to the complexity of the cantilever formwork structure, the large number of components, and the cantilevered state of the formwork, the construction is highly dangerous, and the formwork is prone to overturning during movement. When moving the formwork to the next working segment, the bottom formwork usually moves with the formwork as a whole, while the side and inner formwork usually move separately. Adjusting the formwork position usually takes a lot of time, increasing the workload on site and reducing on-site construction efficiency. In addition, before pouring the box girder concrete, the formwork usually needs to be preloaded to eliminate uneven settlement and inelastic deformation. However, conventional loading methods cannot accurately couple the pouring load, leading to deviation of the beam axis. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hanging basket cantilever system and construction method for large-span, large-section single-box single-cell cast-in-place box girder.

[0004] This large-span, large-section single-box single-cell cast-in-place box girder cantilever system includes a truss system, a formwork support system, an outer formwork system, a telescopic inner formwork system, and a prestressing system; a track beam is installed on the already poured concrete box girder; the truss system slides on the track beam;

[0005] The formwork support system includes an upper crossbeam and a lower crossbeam. The upper crossbeam has side hangers at both ends, with a hanging rope fixed to the lower end of each side hanger. A frame support crossbeam and a side formwork support crossbeam are horizontally mounted on the side hangers. The lower crossbeam is suspended from the lower end of the hanging rope, and a bottom formwork support crossbeam is mounted on the lower crossbeam via a slope adjustment jack. An inner formwork upper longitudinal beam is fixed to the upper crossbeam, with an inner formwork hanger fixed to the front end of the inner formwork upper longitudinal beam. The lower end of the inner formwork hanger is fixed to an inner formwork lower longitudinal beam extending into the concrete box girder to be poured. The upper crossbeam is supported on the upper part of the truss system. Hydraulic support feet are located below the frame support crossbeam.

[0006] The external formwork system includes a bottom formwork and side formwork. The bottom formwork is placed on the bottom formwork support beam, and the side formwork support beam supports the side formwork. The telescopic internal formwork system is supported on the lower longitudinal beam of the internal formwork. The anti-tension preload system is anchored to the bottom formwork support beam and the ground.

[0007] Preferably, the truss system includes diagonal bracing, horizontal support, vertical support, and sliding support feet. The diagonal bracing, horizontal support, and vertical support form an inverted trapezoidal structure. The truss system is supported on the track beam by the sliding support feet. The truss system includes two sets of inverted trapezoidal structures, with a transverse connecting rod between the two sets of inverted trapezoidal structures. The transverse connecting rod is fixed to the vertical support. The sliding support feet are equipped with anti-locking wheels, which are in close contact with the lower surface of the track beam flange. The rear end of the horizontal support at the bottom of the truss system is equipped with a rear anchor beam, which is anchored to the top plate by anchor bolts and anchor beams.

[0008] Preferably, the track beam is anchored to the top plate of the cast concrete box girder using anchor bolts and anchor beams; a truss system jacking jack is provided between the truss system and the track beam, with one end of the truss system jacking jack fixed to the lower surface of the horizontal support and the other end supported on the anchor beam of the track beam.

[0009] Preferably, the formwork support system includes an upper crossbeam, a lower crossbeam, side hangers, hanging ropes, frame support crossbeams, side formwork support crossbeams, longitudinal distribution beams, platform planks, slope adjustment jacks, bottom formwork support crossbeams, inner formwork upper longitudinal beams, inner formwork lower longitudinal beams, and inner formwork hangers; the upper crossbeams and side hangers are equipped with longitudinal connecting rods to connect the two upper crossbeams and side hangers into a whole.

[0010] Preferably, the external formwork system includes a bottom formwork, side formwork, and a support truss. The side formwork is fixed to the support truss, and the support truss is supported on the side formwork support beam. Square wooden ribs are provided on both the bottom formwork support beam and the support truss. Hydraulic struts are provided between the support truss and the side formwork support beam, and the hydraulic struts are hinged to the support truss and the side formwork support beam respectively. Hydraulic support feet are provided below the frame support beam, and the hydraulic support feet are supported on the cast-in-place concrete box girder segments.

[0011] Preferably, a template support system jack is provided between the template support system and the horizontal support for jacking the template support system; one end of the template support system jack is hinged to the horizontal support and the other end is hinged to the upper crossbeam.

[0012] The construction method for this large-span, large-section single-box single-cell cast-in-place box girder cantilever construction system includes the following construction steps:

[0013] Step 1: Install the track beam on the already poured concrete box girder block 1, and support the sliding struts of the truss system on the track beam; anchor the truss system.

[0014] Step 2: Support the upper crossbeam on the truss system and install the formwork support system;

[0015] Step 3: Install the bottom formwork on the bottom formwork support beam; use hydraulic struts to hinge the side formwork to the side formwork support beam; install the anti-tension preloading system and apply loads step by step to preload the formwork and support system, and carry out the bottom plate and web reinforcement binding operation;

[0016] Step 4: Hoist the telescopic inner formwork system onto the lower longitudinal beam of the inner formwork and tie the top slab reinforcement;

[0017] Step 5: Pour concrete box girder, retract the slope adjustment jack to separate the bottom formwork from the bottom plate, retract the hydraulic strut to separate the side formwork from the web plate, retract the inner formwork telescopic screw, and fold the telescopic inner formwork system.

[0018] Preferably, the telescopic inner mold system includes an inner mold plate and inner mold side plates. The inner mold side plates are formed by hinged two plates. The inner mold plate is a complete plate. The two inner mold plates and the two inner mold side plates form a quadrilateral. The plates are hinged to each other. The inner mold plate is supported on the inner mold longitudinal beam. The inner mold longitudinal beam is supported on the inner mold transverse beam. There is a telescopic inner mold screw that is hinged to the inner mold transverse beam and the inner mold side plates. The telescopic inner mold system is supported on the lower inner mold longitudinal beam through the inner mold transverse beam. In step four, the telescopic inner mold screw is adjusted to make the telescopic inner mold system in the unfolded state.

[0019] Preferably, step five is followed by steps six through eight:

[0020] Step Six: Extend the hydraulic struts to support the concrete box girder poured in Step Five. Lift the formwork support system from the truss system, lay the track beam on the newly poured concrete box girder, then release the anchorage of the truss system, push the truss system forward onto the newly laid track beam, and anchor the truss system again after it is in place.

[0021] Step 7: Push the formwork support system, along with the outer formwork system and the telescopic inner formwork system on it, forward to the next working section. After pushing it into place, readjust the bottom formwork and side formwork, unfold the telescopic inner formwork system, and tie the concrete box girder reinforcement.

[0022] Step 8: Repeat steps 5 through 7 until all concrete box girders have been cast in place.

[0023] As a preferred embodiment, step seven specifically involves: a template support system jacking jack is installed between the template support system and the horizontal support. One end of the template support system jacking jack is hinged to the horizontal support, and the other end is hinged to the upper crossbeam. The hydraulic support feet are retracted to allow the template support system to rest on the truss system. Then, the template support system jacking jacking jacking jacking jacking jacks the template support system, along with the outer formwork system and the telescopic inner formwork system on it, is activated to push the template support system forward to the next working section. After being pushed into place, the bottom formwork is adjusted into place using slope adjustment jacks, and the side formwork is adjusted into place using hydraulic struts. The bottom plate and web reinforcement are then tied. Finally, the telescopic inner formwork system is adjusted into place using the inner formwork telescopic screws, and the top plate reinforcement is tied.

[0024] The beneficial effects of this invention are:

[0025] 1) The truss system and the formwork support system can move independently, and the truss system has an inverted trapezoidal structure. The formwork support system does not affect the forward movement of the truss system. When the truss system moves forward, the formwork support system and the load on it are supported on the already well-maintained beam segment. After the truss system has moved forward and been anchored, the formwork support system can be moved forward again, which improves the safety of the hanging basket during the travel phase.

[0026] 2) The outer formwork system and the telescopic inner formwork system are supported on the lower longitudinal beam of the inner formwork of the formwork support system and move forward synchronously with the formwork support system, reducing on-site operation steps and improving the safety and efficiency of formwork movement.

[0027] 3) The formwork inside the concrete box girder adopts a telescopic internal formwork system, which reduces the difficulty of setting up and dismantling the internal formwork and improves the formwork efficiency.

[0028] 4) By setting up a reverse tension preloading system between the bottom formwork support beam and the ground, the formwork support system is subjected to reverse tension preloading. The preloading load is coupled with the beam segment pouring load, which improves the quality of preloading and ensures that the quality of the beam segment alignment meets the design requirements. Attached Figure Description

[0029] Figure 1 This is a front view of the truss system;

[0030] Figure 2 This is a side view of the truss system;

[0031] Figure 3 This is the front view of the template support system;

[0032] Figure 4 This is a side view of the template support system;

[0033] Figure 5 This is a front view of the outer mold structure;

[0034] Figure 6 This is a front view of the internal mold structure in its unfolded state;

[0035] Figure 7 This is a front view of the internal mold structure in its contracted state;

[0036] Figure 8 This is a front view of the cast-in-place operation of the cast-in-place box girder hanging basket system;

[0037] Figure 9 This is a side view of the cast-in-place operation of the cast-in-place box girder hanging basket system;

[0038] Figure 10 This is a front view of the template support system and the separation of the inner and outer templates;

[0039] Figure 11 This is a side view of the template support system and the inner and outer templates in a separated state;

[0040] Figure 12 This is a forward-moving side view of the truss support system;

[0041] Figure 13 This is a front view of the formwork support system and the movement of the inner and outer formwork to the next beam segment;

[0042] Figure 14 This is a side view of the formwork support system and the movement of the inner and outer formwork to the next beam segment.

[0043] The diagram is labeled as follows: 1-Concrete box girder, 11-Top slab, 12-Bottom slab, 13-Web plate, 2-Truss system, 21-Diagonal brace, 22-Horizontal support, 23-Vertical support, 24-Transverse connecting rod, 25-Sliding support foot, 26-Reverse pulley, 27-Truss system jacking jack, 31-Railway beam, 32-Rear anchor beam, 33-Anchor bolt, 34-Anchor beam, 4-Formwork support system, 41-Upper beam, 42-Lower beam, 43-Side hanger, 44-Longitudinal connecting rod, 45-Hanging rope, 46-Frame support beam, 47-Side formwork support 48-Hydraulic support foot, 49-Hydraulic support rod, 410-Longitudinal distribution beam, 411-Platform plank, 412-Adjusting slope jack, 413-Bottom formwork support beam, 414-Upper longitudinal beam of inner formwork, 415-Lower longitudinal beam of inner formwork, 416-Inner formwork hanging rod, 417-Push jack of formwork support system, 51-Bottom formwork, 52-Side formwork, 53-Support truss, 54-Square wooden joists, 55-Inner formwork flat plate, 56-Inner formwork side plate, 57-Inner formwork longitudinal beam, 58-Inner formwork crossbeam, 59-Inner formwork telescopic screw, 61-Reverse pull jack, 62-Steel strand. Detailed Implementation

[0044] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0045] Example 1

[0046] As one example, such as Figures 1 to 14 As shown, this large-span, large-section single-box single-cell cast-in-place box girder cantilever system includes a truss system 2, a formwork support system 3, an outer formwork system, a telescopic inner formwork system, and a prestressing system.

[0047] The truss system 2 includes diagonal bracing 21, horizontal support 22, vertical support 23, and sliding support foot 25. The diagonal bracing 21, horizontal support 22, and vertical support 23 form an inverted trapezoidal structure. The truss system 2 is supported on the track beam 31 by the sliding support foot 25.

[0048] The formwork support system 4 includes an upper horizontal beam 41, a lower horizontal beam 42, side hangers 43, hanging ropes 45, a frame support horizontal beam 46, a side formwork support horizontal beam 47, a longitudinal distribution beam 410, a platform wooden board 411, a slope adjustment jack 412, a bottom formwork support horizontal beam 413, an inner formwork upper longitudinal beam 414, an inner formwork lower longitudinal beam 415, and an inner formwork hanger 416.

[0049] The side hanger 43 is vertically fixed to the end of the upper crossbeam 41, and the suspension rope 45 is fixed to the lower end of the side hanger 43. The side hanger 43 is provided with a frame support crossbeam 46 and a side formwork support crossbeam 47. The lower crossbeam 42 is suspended from the lower end of the suspension rope 45. The longitudinal distribution beam 410, platform wooden board 411, slope adjustment jack 412 and bottom formwork support crossbeam 413 are set on the lower crossbeam 42. The inner formwork upper longitudinal beam 414 is vertically fixed to the upper crossbeam 41. The inner formwork hanger 416 is fixed to the end of the inner formwork upper longitudinal beam 414. The inner formwork lower longitudinal beam 415 is fixed to the lower end of the inner formwork hanger 416. The formwork support system 4 is supported on the horizontal support 22 on the upper part of the truss system 2 through the upper crossbeam 41.

[0050] The outer mold system includes a bottom mold 51, a side mold 52, and a support truss 53. The bottom mold 51 is placed on the bottom mold support beam 413, the side mold 52 is fixed to the support truss 53, and the support truss 53 is supported on the side mold support beam 47. Square wooden ribs 54 are provided on both the bottom mold support beam 413 and the support truss 53 to evenly transfer the pressure of the bottom mold 51 and the side mold 52 to the bottom mold support beam 413 and the support truss 53. A hydraulic strut 49 is provided between the support truss 53 and the side mold support beam 47, and the hydraulic strut 49 is hinged to the support truss 53 and the side mold support beam 47 respectively.

[0051] The telescopic inner mold system includes an inner mold plate 55 and an inner mold side plate 56. The inner mold side plate 56 is formed by two plates hinged together. The inner mold plate 55 is a complete plate. The two inner mold plates 55 and the two inner mold side plates 56 form a quadrilateral. The plates are hinged to each other. The inner mold plate 55 is supported on the inner mold longitudinal beam 57. The inner mold longitudinal beam 57 is supported on the inner mold transverse beam 58. The inner mold transverse beam 58 and the inner mold side plate 56 are provided with an inner mold telescopic screw 59 that is hinged to each other. The telescopic inner mold system is supported on the inner mold lower longitudinal beam 415 by the inner mold transverse beam 58.

[0052] The anti-tension preloading system includes anti-tension jacks 61 and steel strands 62. One end of the anti-tension jacks 61 is anchored to the lower surface of the bottom formwork support beam 413 through the steel strands 62, and the other end is anchored to the ground through the steel strands 62.

[0053] Example 2

[0054] As another embodiment, this second embodiment proposes a more specific large-span, large-section single-box single-cell cast-in-place box girder hanging basket cantilever system based on the first embodiment.

[0055] The track beam 31 is supported on the top plate 11 of the concrete box girder 1 and is anchored to the top plate 11 by anchor bolts 33 and anchor beams 34.

[0056] The truss system 2 consists of two sets of inverted trapezoidal structures, with a transverse connecting rod 24 between the two sets of inverted trapezoidal structures. The transverse connecting rod 24 is fixed to the vertical support 23. The sliding support foot 25 is equipped with a reverse buckle wheel 26, which is in close contact with the lower surface of the wing plate of the track beam 31. The rear end of the horizontal support 22 at the bottom of the truss system 2 is equipped with a rear anchor beam 32, which is anchored to the top plate 11 by anchor bolts 33 and anchor beams 34.

[0057] A truss system jacking jack 27 is provided between the truss system 2 and the track beam 31. One end of the truss system jacking jack 27 is fixed to the lower surface of the horizontal support 22, and the other end is supported on the anchor beam 34 of the track beam 31. The truss system jacking jack 27 is used to push the truss system 2 forward to carry out the construction work of the next beam segment.

[0058] The upper crossbeam 41 and the side hanger 43 are provided with longitudinal connecting rods 44, which connect the two upper crossbeams 41 and the side hanger 43 into a whole, thereby improving the stability of the structure.

[0059] Hydraulic support feet 48 are provided on the frame support beam 46. The hydraulic support feet 48 support the cast-in-place concrete box girder segment 1. The frame support beam 46 and the hydraulic support feet 48 support the load of the formwork support system 4, together with the outer formwork system and the inner formwork system on it, on the cast-in-place concrete box girder segment 1. After the truss system 2 is moved forward and anchored in place, the formwork support system 4 is supported on the truss system 2 and moved forward to the next beam segment to be cast.

[0060] A template support system jack 417 is installed between the template support system 4 and the horizontal support 22. One end of the template support system jack 417 is hinged to the horizontal support 22 and the other end is hinged to the upper crossbeam 41. The template support system jack 417 is used to push the template support system 4 forward to carry out the construction work of the next beam segment.

[0061] The load of the anti-tension jack 61 is coupled with the load of the cast beam segment and applied step by step to improve the preloading effect.

[0062] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0063] Example 3

[0064] As another embodiment, this third embodiment, based on embodiments one and two, proposes a construction method for a large-span, large-section single-box single-cell cast-in-place box girder cantilevered system, including the following construction steps:

[0065] Step 1: Install the track beam 31 on the 0-1 blocks of the poured concrete box girder 1, and anchor it to the top plate 11 using the anchor beam 34 and anchor bolt 33. Then install the truss system 2 on the track beam 31. The sliding support leg 25 of the truss system 2 is supported on the track beam 31. Then install the rear anchor beam 32 at the rear end of the horizontal support 22 at the bottom of the truss system 2, and anchor the rear anchor beam 32 to the top plate 11 using the anchor beam 34 and anchor bolt 33.

[0066] Step 2: Install the formwork support system 4: Support the upper crossbeam 41 on the truss system 2, install side hangers 43 at both ends of the upper crossbeam 41, then install longitudinal connecting rods 44 on the upper crossbeam 41 and the side hangers 43, then suspend the lower crossbeam 42 at the lower end of the side hangers 43 by the suspension rope 45, install the longitudinal distribution beam 410 on the lower crossbeam 42 and lay the platform wooden planks 411, then install the slope adjustment jacks 412 and the bottom formwork support crossbeam 413 on it; vertically fix the inner formwork upper longitudinal beam 414 on the upper crossbeam 41, install the inner formwork hanger 416 at the end of the inner formwork upper longitudinal beam 414, and install the inner formwork lower longitudinal beam 415 at the lower end of the inner formwork hanger 416;

[0067] Step 3, External Formwork System Installation: Lay square wooden joists 54 on the bottom formwork support beam 413, and then lay the bottom formwork 51 on the square wooden joists 54; hoist the side formwork 52 and support truss 53 as a whole onto the side formwork support beam 47, and use hydraulic struts 49 to hinge them to the support truss 53 and the side formwork support beam 47 respectively; adjust the bottom formwork 51 to the designated position using the slope jack 412, and adjust the side formwork 52 to the designated position using the hydraulic struts 49; then, anchor one end of the counter-pull jack 61 to the lower surface of the bottom formwork support beam 413 through steel strands 62, and anchor the other end to the ground through steel strands 62; open the counter-pull jack 61 to apply loads step by step to pre-stress the formwork and formwork support system 4; the load of the counter-pull jack 61 is coupled with the pouring load; after the pre-stressing is completed, carry out the reinforcement binding operation of the bottom plate 12 and web plate 13.

[0068] Step 4: Installation of the telescopic inner formwork system: The entire telescopic inner formwork system is hoisted onto the lower longitudinal beam 415 of the inner formwork, and the telescopic screws 59 of the inner formwork are adjusted to be in the extended state. Then, the top plate 11 reinforcement bars are tied.

[0069] Step 5: After the formwork and reinforcement are installed, the concrete box girder 1 is poured. The bottom plate 12, web 13 and top plate 11 are poured in sequence from bottom to top. After the pouring is completed, the concrete is cured.

[0070] After the concrete has been cured to the design strength, the slope adjustment jack 412 is retracted to separate the bottom formwork 51 from the bottom plate 12, the hydraulic strut 49 is retracted to separate the side formwork 52 from the web plate 13, and the inner formwork telescopic screw 59 is retracted to put the inner formwork in a folded state.

[0071] Truss system 2 moves forward: Extend hydraulic support legs 48, lift formwork support system 4 from truss system 2 and support it on the top plate 11 of the newly poured concrete box girder 1, lay track beam 31 on the newly poured concrete box girder 1 and anchor it with anchor bolts 33 and anchor beams 34, then release the anchor beams 34 and anchor bolts 33 on the rear anchor beam 32, start the truss system jacking jack 27 to push truss system 2 forward, and after jacking into place, use anchor beams 34 and anchor bolts 33 to anchor the rear anchor beam 32 on the top plate 11 again;

[0072] The template support system 4 is moved forward: the hydraulic support feet 48 are retracted so that the template support system 4 is supported on the truss system 2. Then, the template support system jacking jack 417 is activated to push the template support system 4, together with the outer formwork system and the inner formwork system on it, forward to the next working section. After being pushed into place, the bottom formwork 51 is adjusted into place by the slope adjustment jack 412, and the side formwork 52 is adjusted into place by the hydraulic support rod 49. The bottom plate 12 and the web plate 13 reinforcement are tied. Then, the inner formwork is adjusted into place by the inner formwork telescopic screw 59, and the top plate 11 reinforcement is tied.

[0073] After the formwork and reinforcing bars are tied in place, the beam is poured, and the above steps are repeated for grouting to carry out the cast-in-place construction of the concrete box girder 1.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A cantilevered formwork system for large-span, large-section single-box, single-cell cast-in-place box girder, characterized in that, It includes a truss system, a formwork support system, an outer formwork system, a telescopic inner formwork system, and a prestressing system; a track beam is installed on the poured concrete box girder; the truss system slides on the track beam; The formwork support system includes an upper crossbeam and a lower crossbeam. The upper crossbeam has side hangers at both ends, with a hanging rope fixed to the lower end of the side hangers. A frame support crossbeam and a side formwork support crossbeam are horizontally mounted on the side hangers. The lower crossbeam is suspended from the lower end of the hanging rope. A bottom formwork support crossbeam is mounted on the lower crossbeam via a slope adjustment jack. An inner formwork upper longitudinal beam is fixed on the upper crossbeam. An inner formwork hanger is fixed to the front end of the inner formwork upper longitudinal beam. The lower end of the inner formwork hanger is fixed to an inner formwork lower longitudinal beam that extends into the box girder of concrete to be poured. The upper crossbeam is supported on the upper part of the truss system. Hydraulic support feet are installed below the crossbeams supporting the frame; The external formwork system includes a bottom formwork and side formwork. The bottom formwork is placed on the bottom formwork support beam, and the side formwork support beam supports the side formwork. The telescopic internal formwork system is supported on the lower longitudinal beam of the internal formwork. The anti-tension preload system is anchored to the bottom formwork support beam and the ground.

2. The large-span, large-section single-box, single-cell cast-in-place box girder cantilever construction system according to claim 1, characterized in that, The truss system includes diagonal bracing, horizontal bracing, vertical bracing, and sliding support feet. The diagonal bracing, horizontal bracing, and vertical bracing form an inverted trapezoidal structure. The truss system is supported on the track beam by the sliding support feet. The truss system includes two sets of inverted trapezoidal structures, with a transverse connecting rod between the two sets of inverted trapezoidal structures. The transverse connecting rod is fixed to the vertical bracing. The sliding support feet are equipped with anti-locking wheels, which are in close contact with the lower surface of the track beam flange. The rear end of the horizontal bracing at the bottom of the truss system is equipped with a rear anchor beam, which is anchored to the top plate by anchor bolts and anchor beams.

3. The large-span, large-section single-box, single-cell cast-in-place box girder cantilever construction system according to claim 2, characterized in that, The track beam is anchored to the top plate of the cast concrete box girder using anchor bolts and anchor beams; a truss system jacking jack is installed between the truss system and the track beam, with one end of the truss system jacking jack fixed to the lower surface of the horizontal support and the other end supported on the anchor beam of the track beam.

4. The cantilevered casting system for large-span, large-section single-box, single-cell cast-in-place box girder according to claim 3, characterized in that, The formwork support system includes an upper crossbeam, a lower crossbeam, side hangers, hanging ropes, frame support crossbeams, side formwork support crossbeams, longitudinal distribution beams, platform planks, slope adjustment jacks, bottom formwork support crossbeams, inner formwork upper longitudinal beams, inner formwork lower longitudinal beams, and inner formwork hangers; longitudinal connecting rods are provided on the upper crossbeams and side hangers to connect the two upper crossbeams and side hangers into a whole.

5. The large-span, large-section single-box, single-cell cast-in-place box girder cantilever construction system according to claim 4, characterized in that, The external formwork system includes a bottom formwork, side formwork, and a support truss. The side formwork is fixed to the support truss, and the support truss is supported on the side formwork support beams. Square wooden ribs are provided on both the bottom formwork support beams and the support truss. Hydraulic struts are provided between the support truss and the side formwork support beams, and the hydraulic struts are hinged to the support truss and the side formwork support beams respectively. Hydraulic support feet are provided below the frame support beams, and the hydraulic support feet are supported on the cast-in-place concrete box girder segments.

6. The cantilevered casting system for large-span, large-section single-box single-cell cast-in-place box girder according to claim 5, characterized in that, A jacking jack for the formwork support system is installed between the formwork support system and the horizontal support for jacking the formwork support system. One end of the jacking jack is hinged to the horizontal support and the other end is hinged to the upper crossbeam.

7. A construction method based on the large-span, large-section single-box single-cell cast-in-place box girder cantilever construction system described in claim 6, characterized in that, The construction steps include the following: Step 1: Install the track beam on the poured concrete box girder 0-1 blocks, and anchor the truss system by supporting the sliding support feet of the truss system on the track beam. Step 2: Support the upper crossbeam on the truss system and install the formwork support system; Step 3: Install the bottom formwork on the bottom formwork support beam; The side formwork support beam is hinged to the side formwork using hydraulic struts. Install the anti-tension preloading system and apply loads step by step to preload the formwork and support system, and carry out the bottom slab and web reinforcement binding work; Step 4: Hoist the telescopic inner formwork system onto the lower longitudinal beam of the inner formwork and tie the top slab reinforcement; Step 5: Pour concrete box girder, retract the slope adjustment jack to separate the bottom formwork from the bottom plate, retract the hydraulic strut to separate the side formwork from the web plate, retract the inner formwork telescopic screw, and fold the telescopic inner formwork system.

8. The construction method of the large-span, large-section single-box single-cell cast-in-place box girder cantilever construction system according to claim 7, characterized in that, The telescopic inner mold system includes an inner mold plate and inner mold side plates. The inner mold side plates are formed by hinged two plates. The inner mold plate is a complete plate. The two inner mold plates and the two inner mold side plates form a quadrilateral. The plates are hinged to each other. The inner mold plate is supported on the inner mold longitudinal beam. The inner mold longitudinal beam is supported on the inner mold transverse beam. There is a telescopic inner mold screw that is hinged to the inner mold transverse beam and the inner mold side plates. The telescopic inner mold system is supported on the lower inner mold longitudinal beam through the inner mold transverse beam. In step four, the telescopic inner mold screw is adjusted to make the telescopic inner mold system in the unfolded state.

9. The construction method of the large-span, large-section single-box single-cell cast-in-place box girder cantilever construction system according to claim 8, characterized in that, Step five is followed by steps six through eight: Step Six: Extend the hydraulic struts to support the formwork of the concrete box girder poured in Step Five. Lift the formwork support system from the truss system, lay the track beam on the newly poured concrete box girder, then release the anchorage of the truss system, push the truss system forward onto the newly laid track beam, and anchor the truss system again after it is in place. Step 7: Push the formwork support system, along with the outer formwork system and the telescopic inner formwork system on it, forward to the next working section. After pushing it into place, readjust the bottom formwork and side formwork, unfold the telescopic inner formwork system, and tie the concrete box girder reinforcement. Step 8: Repeat steps 5 through 7 until all concrete box girders have been cast in place.

10. The construction method of the large-span, large-section single-box single-cell cast-in-place box girder cantilever construction system according to claim 9, characterized in that, Step seven is as follows: A template support system jacking jack is installed between the template support system and the horizontal support. One end of the template support system jacking jack is hinged to the horizontal support, and the other end is hinged to the upper crossbeam. The hydraulic support feet are retracted to allow the template support system to fall onto the truss system. Then, the template support system jacking jack is activated to push the template support system, along with the outer formwork system and the telescopic inner formwork system on it, forward to the next working section. After being pushed into place, the bottom formwork is adjusted into place using the slope adjustment jack, and the side formwork is adjusted into place using the hydraulic support rods. The bottom plate and web reinforcement are then tied. Finally, the telescopic inner formwork system is adjusted into place using the inner formwork telescopic screw rods, and the top plate reinforcement is tied.

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