Construction system and method of super-wide variable cross-section multi-box cast-in-situ box girder

Abstract

The application discloses a kind of super-wide variable cross-section multi-box chamber cast-in-place box girder construction system and construction method, belong to bridge engineering construction technical field.The present application aims to solve the technical problems of cast-in-place box girder construction, such as unstable support of flange plate, difficulty in adapting variable cross-section of box room formwork, low precision of wide roof leveling, and uncontrollable unloading of support sand box.The technical solution points are: using shaped keel support system and positioning rib to support flange plate;Using a sliding formwork system, using adjustable lead screw for fine adjustment, and separating and transporting by bottom chamfer formwork to adapt to variable cross-section;Using laser paving machine to level the roof, the inner side rail steel support is synchronously embedded in the middle web;Using sand box to unload, controlling sand material through 1mm screen and electronic scale, and using push-pull steel baffle to control sand unloading window to achieve uniform speed unloading.The application is used for the construction of super-wide variable cross-section multi-box chamber cast-in-place box girder.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering construction technology, and more specifically, to a construction method for ultra-wide, variable cross-section, multi-cell cast-in-place concrete box girders, as well as a special support system, formwork system and unloading device used in the method, and especially to a construction system and construction method for ultra-wide, variable cross-section, multi-cell cast-in-place box girders. Background Technology

[0002] In modern bridge engineering, ultra-wide variable cross-section multi-cell cast-in-place box girders are widely used due to their excellent load-bearing performance and outstanding adaptability to wide bridge decks. However, their complex structural form poses a severe challenge to traditional construction techniques.

[0003] Firstly, regarding the support of flange plate formwork, traditional methods often involve temporarily assembling scattered components (such as steel pipes and fasteners) on-site. This is not only cumbersome to install and has poor overall stability, but also relies on manual experience when laying timber, making it difficult to guarantee laying accuracy. Furthermore, this support system lacks effective deformation monitoring methods, making it prone to formwork shifting or settlement during concrete pouring, directly affecting the forming quality and structural safety of the flange plate.

[0004] Secondly, in the construction of the inner formwork of the box girder, the traditional fixed inner formwork is extremely unsuitable when faced with box girder with changing cross-sectional dimensions. During construction, it is necessary to frequently and extensively dismantle and reassemble the formwork, which is not only time-consuming and labor-intensive, but also makes component turnover difficult and transportation efficiency low, which seriously restricts the overall construction progress.

[0005] Furthermore, existing technologies for concrete leveling of the top slab of wide box girders largely rely on manual labor combined with simple machinery, making it difficult to achieve large-area, high-precision elevation control, resulting in poor flatness of the top slab. Even with the introduction of automated paving equipment (such as pavers), the stability of the track support system (especially the track in the middle area) is difficult to guarantee on wide bridge decks, especially when multiple machines are working together, posing a risk of instability and thus affecting the final leveling quality.

[0006] Finally, in the scaffold unloading stage after construction, traditional sand box unloading technology generally suffers from problems of rough control. For example, inaccurate particle size screening and weight weighing of the filling sand leads to uncontrollable settlement of the sand box after being compressed; and the sand unloading process (unloading speed) is difficult to control evenly, which can easily lead to uncontrolled scaffold unloading speed, posing a great safety hazard. Summary of the Invention

[0007] To overcome the technical bottlenecks commonly encountered in the construction of ultra-wide variable cross-section box girders, such as unstable and inaccurate flange plate support, low efficiency due to the inability of the inner formwork to adapt to the variable cross-section, low leveling accuracy and unstable support of the wide top plate, and rough and uncontrollable sand box unloading, the present invention aims to provide a construction system and method for ultra-wide variable cross-section multi-compartment cast-in-place box girders. Its core lies in the systematic solution to the stability, accuracy, and efficiency problems in the construction of ultra-wide variable cross-section box girders by employing a flange plate-shaped keel frame support, a flexible sliding and adaptable inner formwork system, laser paver leveling based on pre-embedded supports, and a highly efficient sand box technology that ensures precise control of both sand material and unloading processes.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a construction method for ultra-wide variable cross-section multi-cell cast-in-place box girders, comprising the following steps:

[0009] Flange plate support construction: Set up a lower disc buckle bracket in the flange plate area, and install a fixed keel frame support system on the disc buckle bracket; connect the fixed keel frame support system and the disc buckle bracket with steel pipe couplers to form a truss structure; set positioning ribs above the top channel steel of the fixed keel frame support system to assist in laying timber;

[0010] Construction of the inner formwork of the box: A sliding inner formwork system is used in the box area. The spatial position of the inner formwork is finely adjusted by an adjustable screw to match the inner wall of the box. The sliding inner formwork system is slidable on the I-beam rail by a formwork trolley. When the construction reaches the variable cross-section position, the bottom chamfer formwork in the sliding inner formwork system is removed and transported separately.

[0011] Top slab leveling construction: During the pouring of the middle web slab, the rail steel support for supporting the inner paver track is pre-embedded simultaneously; after the middle web slab and side web slab are poured, the inner paver track and the outer paver track are erected; a laser paver is deployed, and elevation data is collected through laser sensors to level the top slab of the wide box girder.

[0012] Sand box unloading operation: When preparing the sand box, a 1mm sieve is used to screen the filling sand, and an electronic scale is used to weigh the medium sand after screening. Then the medium sand after screening is loaded into the lower sand cylinder. When the support is unloaded, the opening size of the sand unloading window is adjusted by controlling the sliding steel baffle to control the outflow of medium sand after screening.

[0013] Furthermore, during the flange plate support construction: the fixed keel frame support system includes vertical braces, diagonal braces, top channel steel and bottom channel steel; part of the bottom channel steel is erected above the outer formwork base plate; measuring points are set on the top channel steel and vertical braces.

[0014] Furthermore, during the construction of the inner mold of the box: the sliding inner mold system connects the segments through hinge plates, connecting bolts and fixed plates; before sliding, the first hydraulic support rod is used for temporary support, the second hydraulic support rod is retracted and removed, and then replaced with the moving mold trolley; after sliding into place, the moving mold trolley is removed and the second hydraulic support rod is replaced.

[0015] Furthermore, during the slab leveling construction: the laser paver uses a left-side laser paver and a right-side laser paver, which are respectively deployed along both sides of the slab and are located on the inner side paver track; the outer paver track is fixed by a rail steel support, the upper part of which is connected to the guardrail steel cage; the laser paver controls the telescopic mechanism to adjust the position of the paving slab based on the data fed back by the laser sensor.

[0016] Furthermore, during the sand box unloading process: the sand box also includes an upper sand cylinder, the inner cavity of which is filled with C30 concrete; lubricating grease is injected into the gap between the upper and lower sand cylinders.

[0017] A construction system for ultra-wide variable cross-section multi-cell cast-in-place box girders, comprising:

[0018] Flange plate shaped keel frame support system: suitable for installation on the lower disc buckle bracket, and suitable for connection with the disc buckle bracket through steel pipe fasteners to form a truss structure; the shaped keel frame support system includes a top channel steel, and positioning ribs are set on the top channel steel;

[0019] The sliding inner mold system includes an adjustable lead screw suitable for fine-tuning the spatial position of the inner mold, an I-beam rail suitable for supporting the sliding of the sliding inner mold system, and a mold moving trolley; the sliding inner mold system includes a detachable bottom chamfer mold;

[0020] Wide box girder top slab leveling system: includes rail steel supports for supporting the inner paver track and suitable for pre-embedding in the web, inner paver track, outer paver track, and laser paver set on the track, the laser paver is equipped with a laser sensor;

[0021] Sand box: including a sand lowering cylinder and a sliding steel baffle for controlling the opening size of the sand discharge window at the sand lowering cylinder; the system also includes a 1mm screen for screening the filling sand and an electronic scale for weighing the medium sand after screening.

[0022] Furthermore, the flange-shaped frame support system also includes:

[0023] Vertical bracing, diagonal bracing, and bottom channel steel; the bottom channel steel is suitable for erection above the outer formwork base plate; measuring points are set on the top channel steel and vertical bracing.

[0024] Furthermore, the sliding internal mold system also includes:

[0025] The system includes a hinge plate, connecting bolts, and a fixing plate for connecting segments; the system also includes a first hydraulic support rod and a second hydraulic support rod, the second hydraulic support rod being adapted to be replaced by a mold-moving trolley for sliding.

[0026] Furthermore, in the wide-span box girder top slab leveling system:

[0027] The laser paver includes a left-side laser paver and a right-side laser paver, both adapted to be located together on the inner paver track on the inner side; the system also includes a track steel support for fixing the outer paver track, which is adapted to connect to the guardrail steel cage; the laser paver also includes a telescopic mechanism and a paving slab, the telescopic mechanism being adapted to adjust the position of the paving slab based on data feedback from the laser sensor.

[0028] Furthermore, the sandbox also includes:

[0029] The upper sand cylinder is filled with C30 concrete; the gap between the upper and lower sand cylinders is filled with grease.

[0030] Compared with the prior art, the technical solution disclosed in this invention has the following significant advantages:

[0031] 1. Improved stability and precision of flange plate support: The "flange plate shaped keel support technology" of this invention forms a stable truss structure by combining a standardized shaped keel with a disc buckle bracket. The positioning ribs ensure the accuracy of timber laying, and the measuring points are set to monitor deformation in real time, which greatly improves the stability of support and the accuracy of construction, and ensures the safety of operation.

[0032] 2. Achieves efficient adaptation and sliding of the inner mold to variable cross sections: The "sliding inner mold technology" of this invention adopts an assemblable and adjustable inner mold system, using adjustable lead screws and flexible connectors (hinged plates, fixed plates) to ensure that the template is accurately fitted to the box wall; at the same time, it achieves efficient overall sliding with the help of hydraulic support and moving mold trolley, and can also be moved by disassembly (such as bottom chamfering mold) when encountering variable cross sections, which significantly improves the forming quality and construction efficiency of the box chamber.

[0033] 3. Ensures the quality and reliability of wide-span top slab leveling: The "wide-span box girder top slab concrete slurry leveling technology" of this invention adopts the collaborative operation of dual-span laser pavers, and greatly enhances the rigidity and stability of the track support by pre-embedding the steel support of the inner shared track in the middle web concrete. This ensures that the paver can still achieve high-precision slurry leveling operation under high load, thus guaranteeing the leveling quality and structural reliability.

[0034] 4. Achieved safe, precise, and controllable sand box unloading: The "high-efficiency sand box loading and unloading technology" of this invention achieves precise control of sand material (particle size and weight) through a 1mm screen and electronic scale, and reduces friction through lubricating grease; most importantly, the opening size of the sand unloading window is precisely controlled by pushing and pulling steel baffles, which achieves uniform and controllable speed in the support unloading process, ensures unloading safety, and reduces construction costs. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the flange plate shaping keel support technology according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the sliding inner mold technology according to an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the sliding inner mold vertical mold structure according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the formwork shifting construction at the variable cross-section of the sliding inner formwork according to an embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the concrete leveling and grouting technology for the top slab of a wide box girder according to an embodiment of the present invention;

[0040] Figure 6 This is a detailed diagram of node A in an embodiment of the present invention;

[0041] Figure 7 This is a detailed diagram of node B in an embodiment of the present invention;

[0042] Figure 8 This is a schematic diagram of the sand screening construction according to an embodiment of the present invention;

[0043] Figure 9 This is a schematic diagram of the sand box structure according to an embodiment of the present invention.

[0044] Explanation of reference numerals in the attached drawings: 1. Working platform; 2. Flange plate area; 3. Disc-lock top support; 4. Longitudinal steel pipe; 5. Transverse steel pipe; 6. Upright pole; 7. Diagonal tie rod; 8. Timber; 9. Positioning rib; 10. Outer formwork base plate; 11. Measuring point; 12. Vertical brace; 13. Diagonal brace; 14. Top channel steel; 15. Steel pipe fastener; 16. Bottom channel steel; 17. First I-beam; 18. Horizontal bar; 19. Flange template 20. Cast-in-place box girder; 21. Box chamber; 22. Sliding inner formwork system; 23. Steel strip; 24. Steel panel; 25. Inner formwork channel steel; 26. Connecting bolts; 27. Inner formwork base plate; 28. Supporting steel pipe; 29. ​​Angle steel diagonal brace; 30. Section steel support; 31. Hinge plate; 32. Adjustable threaded rod; 33. Fixed plate; 34. Angle steel cross brace; 35. Top seat; 36. Second hydraulic support rod; 37. 38. Second I-beam; 39. First hydraulic support rod; 40. Variable cross-section; 41. Inner wall of the box girder; 42. Bottom chamfered mold; 43. Shifting mold trolley; 44. Left laser paver; 45. Right laser paver; 46. Laser sensor; 47. Top plate; 48. Middle web plate; 49. Side web plate; 50. Bottom plate; 51. Traveling mechanism; 52. Paver track; 53. Top support. 54. Guardrail reinforcement cage; 55. Track steel support; 56. Telescopic mechanism; 57. Paver slab; 58. Separator reinforcement cage; 59. 1mm sieve; 60. Screen bucket; 61. Medium sand after screening; 62. Electronic scale; 63. Sand loading cylinder; 64. C30 concrete; 65. Sand unloading window; 66. Sliding steel baffle; 67. Lubricating grease; 68. Sand lower cylinder; 69. Bottom steel plate; 70. Steel pipe column. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] Example 1

[0047] This invention provides a construction system and method for ultra-wide variable cross-section multi-cell cast-in-place box girders. It solves existing construction problems by integrating four major technologies (flange plate shaping keel support technology, sliding inner formwork technology, wide box girder top plate concrete leveling technology, and sand box high-efficiency loading and unloading technology).

[0048] The following is in conjunction with the appendix Figure 1 To be continued Figure 9 A preferred embodiment of the present invention will be described in detail below.

[0049] I. Construction of the flange plate shaping keel support (S1)

[0050] Please see Figure 1 In this embodiment, the flange plate support construction mainly adopts a flange plate shaped keel frame support system in flange plate area 2.

[0051] First, install the lower disc buckle bracket. Precisely locate the installation point of the disc buckle bracket upright 6 in the flange plate area 2. Install the disc buckle bracket upright 6, horizontal bar 18 and diagonal tie rod 7, and install the disc buckle top support 3 on the top of the upright 6 and place the first I-beam 17.

[0052] Next, the standardized truss support system is installed. This system mainly consists of vertical supports 12, diagonal supports 13, top channel steel 14, and bottom channel steel 16. The uprights 6 and vertical supports 12 are connected to the transverse steel pipes 5 and longitudinal steel pipes 4 of the disc-lock bracket via steel pipe couplers 15, forming a stable and reliable truss structure. To enhance load-bearing coordination, the inner end of the bottom channel steel 16 is placed above the outer formwork base plate 10.

[0053] To ensure construction accuracy, positioning ribs 9 are installed above the top channel steel 14 to assist in laying the timber 8 and ensure the accuracy of the timber 8 laying. Then, the flange formwork 19 is installed.

[0054] In order to monitor the stability of the support system in real time, measuring points 11 are set at corresponding positions of the top channel steel 14 and the vertical brace 12 to monitor the deformation of the support system during construction.

[0055] Finally, the work platform 1 is attached to the tail of the top channel steel 14 to provide a safe working area for on-site workers.

[0056] II. Construction of the Inner Formwork of the Box Container (S2)

[0057] Please see Figure 2 , Figure 3 and Figure 4 In this embodiment, the construction of the inner formwork of the box girder mainly adopts the sliding inner formwork system 22 in the box chamber 21 area of ​​the cast-in-place box girder 20.

[0058] First, the bottom support structure is erected. The inner formwork base plate 27 is placed at the bottom of the container, the supporting steel pipes 28 are installed, and the I-beam rails 37 and the second I-beam 38 are laid.

[0059] Next, the central stabilizing support structure is constructed. The first hydraulic support rod 39, the second hydraulic support rod 36, and the top seat 35 are installed, and connected and reinforced with the steel support 30, angle steel diagonal brace 29, and angle steel horizontal brace 34 to ensure the rigidity and stability of the central support system.

[0060] Next, the inner mold system is assembled. The sliding inner mold system 22 mainly consists of steel panels 24, steel strips 23, and inner mold channel steel 25. These components are assembled in sections using hinge plates 31, connecting bolts 26, and fixing plates 33. The spatial position of the inner mold is finely adjusted using adjustable screws 32, allowing the steel panels 24 to precisely fit the inner walls 41 of different sizes of the box. After installation, the steel panels 24 are spliced ​​and fixed to the inner mold base plate 27 below, completing the installation of the inner mold for the current section.

[0061] After the cast-in-place work is completed, preparations for sliding are made. First, the I-beam rail 37 is extended and reinforced, the connecting bolts 26 between the formwork are released, and the adjustable threaded rods 32 on the side are removed to retract the side formwork. Temporary support is provided by the first hydraulic support rod 39, while the second hydraulic support rod 36 is retracted and removed, and replaced with the formwork moving trolley 43.

[0062] Using the formwork transfer trolley 43, the main body of the sliding inner formwork system 22 is slid along the I-beam rail 37 to the next construction position. A key aspect of this invention is that when construction encounters a variable cross-section 40 that restricts the size of the chamber (e.g.... Figure 4 As shown), the bottom chamfer mold 42 can be removed separately, allowing the bottom chamfer mold 42 to be moved independently, while the remaining components are slid together via the mold-moving trolley 43, thus flexibly adapting to the construction requirements of variable cross sections.

[0063] After sliding into place, the mold transfer trolley 43 is removed and the second hydraulic support rod 36 is replaced. According to the current size of the chamber, appropriate components are selected for splicing (or customized components are replaced), and the position of the inner mold is finely adjusted again through the adjustable screw 32 to ensure that the steel panel 24 fits the inner wall 41 of the chamber.

[0064] III. Roof Slab Leveling Construction (S3)

[0065] Please see Figure 5 , Figure 6 and Figure 7 In this embodiment, the concrete leveling and grouting construction of the top slab of the wide box girder 47 uses a wide box girder top slab leveling system.

[0066] First, complete the pouring of the substructure, including the bottom slab 50, the side web 49, and the middle web 48, and ensure that the concrete strength meets the standards.

[0067] A key step in this embodiment is to simultaneously embed rail steel supports 55 for supporting the inner paver track 52 during the pouring of the web plate 48, so that its lower part is fixed to the pouring of the web plate 48.

[0068] Next, the paver track 52 is erected. The outer paver track 52 is fixed by a top support 53 and a track steel support 55. The upper part of the track steel support 55 is connected to the guardrail reinforcement cage 54, and the lower part is connected to the reinforcement in the top slab 47. The inner shared paver track 52 is laid on the track steel support 55 pre-embedded in the middle web slab 48. The upper part of the track steel support 55 is connected and fixed to the reinforcement in the top slab 47 and the divider reinforcement cage 58. This double fixing method, especially the pre-embedded technology of the inner track, greatly ensures the stability of the track system.

[0069] Then, a left-side laser paver 44 and a right-side laser paver 45 are installed along both sides of the top plate 47, both located on the inner paver track 52. This ensures that the paver's traveling mechanism 51 is adapted to the paver track 52.

[0070] During concrete pouring, the leveling and grouting operation is initiated. Laser sensor 46 collects elevation data in real time and feeds it back to the control system. The traveling mechanisms 51 of the left-side laser paver 44 and the right-side laser paver 45 move synchronously along the track, and the paving slab 57 levels the concrete. Based on the data fed back by the laser sensor 46, the control system adjusts the position of the paving slab 57 via the telescopic mechanism 56, precisely controlling the flatness of the paving top slab 47.

[0071] IV. Sandbox Removal Operation (S4)

[0072] Please see Figure 8 and Figure 9 The sand box loading and unloading operation in this embodiment is used for the precise unloading of the support frame.

[0073] First, the sand is screened and weighed. The filler sand is poured into the sieve 60 and screened through the 1mm screen 59 at the top of the sieve 60 to remove impurities and sand with excessive particle size. The screened medium sand 61 falls naturally into the electronic scale 62 below for accurate weighing to ensure that the filling amount of each sand box is consistent.

[0074] Next, the sand box is prepared. The sand box mainly consists of an upper sand cylinder 63 and a lower sand cylinder 68. First, C30 concrete 64 is poured into the inner cavity of the upper sand cylinder 63 to increase its self-weight and rigidity. Then, the sieved medium sand 61 that meets the weight requirements is evenly loaded into the lower sand cylinder 68. After the concrete reaches the design strength, the upper sand cylinder 63 and the lower sand cylinder 68 are assembled accordingly, and lubricating grease 67 is evenly injected into the gap between them to form a sealing and friction-reducing layer, reducing the frictional resistance during subsequent unloading.

[0075] The bottom steel plate 69 at the bottom of the lower sand cylinder 68 is welded and fixed to the steel pipe column 70 below.

[0076] Finally, the unloading operation is carried out. The key to this embodiment lies in the precise control of the unloading. According to the required unloading speed, the opening size of the sliding steel baffle 66 at the sand unloading window 65 is controlled so that the medium sand 61 after screening in the lower sand cylinder 68 flows out at a uniform speed, thereby achieving precise unloading control of the sand box and ensuring that the support is unloaded safely and stably.

[0077] Example 2

[0078] Based on the same concept, this embodiment provides more detailed construction methods and steps:

[0079] S1. During the construction of the flange plate styling frame support, accurately locate the installation points of the disc-lock scaffold uprights 6 in the flange plate area 2. Next, use a hoisting device to install the uprights 6, horizontal bars 18, and diagonal braces 7 of the disc-lock scaffold. Install the disc-lock top support 3 on the top of the uprights 6 and place the first I-beam 17 to complete the installation of the lower disc-lock scaffold. Then, install the styling frame support system. Connect the uprights 6, vertical supports 12, and the transverse and longitudinal steel pipes 5 and 4 of the disc-lock scaffold using steel pipe couplers 15 to form a truss structure. The inner end of the bottom channel steel 16 is placed above the outer formwork base plate 10 to enhance load-bearing coordination. Next, set positioning ribs 9 above the top channel steel 14 to assist in laying timber 8 to ensure laying accuracy. Then, install the flange formwork 19. Simultaneously, set measuring points 11 at corresponding positions on the top channel steel 14 and vertical supports 12 to monitor the deformation of the support system. Finally, attach the working platform 1 to the tail of the top channel steel 14 to provide a safe area for on-site operations.

[0080] S2. During the construction of the sliding inner formwork for the box girder 20 box chamber 21, the inner formwork base plate 27 is placed at the bottom of the box chamber, the supporting steel pipe 28 is installed, and the I-beam rail 37 and the second I-beam 38 are laid to complete the erection of the bottom support structure. Next, the central stable support structure is built, and the first hydraulic support rod 39, the second hydraulic support rod 36 and the top seat 35 are installed. They are connected and reinforced with the steel section support 30, the angle steel diagonal brace 29 and the angle steel horizontal brace 34 to ensure the rigidity and stability of the central support system. After that, the inner formwork system is assembled. The steel panel 24, steel strip 23, inner formwork channel steel 25 and other components are assembled in sections by means of the hinge plate 31, connecting bolts 26 and fixing plate 33. The spatial position of the inner formwork is finely adjusted by the adjustable screw rod 32 so that the steel panel 24 is precisely fitted to the inner wall 41 of the box chamber. The steel panel 24 is spliced ​​and fixed to the inner formwork base plate 27 below to complete the installation of the inner formwork of the current section to cooperate with the cast-in-place operation. Subsequently, after the cast-in-place work is completed, preparations for sliding are made. First, the I-beam rail 37 is extended and reinforced, the connecting bolts 26 between the formwork are released, the adjustable side screw rods 32 are removed and the side formwork is retracted, and temporary support is provided by the first hydraulic support rod 39. The second hydraulic support rod 36 is then retracted and removed, and replaced with a formwork trolley 43. With the help of the formwork trolley 43, the main body of the sliding inner formwork system 22 is slid on the I-beam rail 37 to the next construction position. If the cross-section 40 causes the size of the box girder to be limited, the bottom chamfered formwork 42 is removed and moved separately. Finally, after sliding into place, the formwork trolley 43 is removed and the second hydraulic support rod 36 is replaced. Appropriate components are selected and spliced ​​according to the size of the box girder at the current construction position. The positions of each component of the inner formwork are finely adjusted by the adjustable screw rod 32 to ensure that the steel panel 24 fits the inner wall 41 of the box girder. The formwork support and moving steps are repeated to complete the construction of all beams.

[0081] S3. When carrying out the concrete leveling and grouting construction of the top slab 47 of the wide-span cast-in-place box girder, first complete the pouring of the bottom slab 50, side web 49, and middle web 48, ensuring that the lower concrete strength meets the standards. During the pouring of the middle web 48, simultaneously embed the rail steel support 55 corresponding to the inner paver track 52, fixing its lower part to the middle web 48 during pouring. Next, erect the paver track 52. The outer paver track 52 is fixed by the top support 53 and the rail steel support 55. The upper part of the rail steel support 55 is connected to the guardrail reinforcement cage 54, and the lower part is connected to the reinforcement in the top slab 47. The inner shared paver track 52 is laid on the embedded rail steel support 55. The upper part of the rail steel support 55 is connected and fixed to the reinforcement in the top slab 47 and the divider reinforcement cage 58 to ensure the stability of the overall track system. Subsequently, a left-side laser paver 44 and a right-side laser paver 45 are deployed along both sides of the top slab 47, ensuring that the paver's traveling mechanism 51 is adapted to the paver track 52. The laser sensor 46 is adjusted to accurately collect elevation data, and the linkage performance between the telescopic mechanism 56 and the paving slab 57 is calibrated. Then, concrete pouring operations are carried out in the area of ​​the top slab 47. Following this, during the concrete pouring process, a leveling operation is initiated. The laser sensor 46 collects elevation data in real time and feeds it back to the control system. The paver traveling mechanisms 51 of the left-side and right-side laser pavers 44 and 45 move synchronously along the paver track 52. The paving slab 57 levels the concrete, and the control system adjusts the position of the paving slab 57 via the telescopic mechanism 56 based on the data, precisely controlling the flatness of the top slab 47. Finally, after the concrete leveling and grouting of the top slab 47 is completed, the laser paver system is shut down, and the surface flatness and elevation of the top slab 47 are checked. After confirming that it meets the design requirements, the laser paver and paver track 52 are removed, completing the entire leveling and grouting construction process.

[0082] S4. During the sand box loading and unloading operation, the sand screening and weighing operation is carried out first. The filling sand is poured into the screen hopper 60 and screened through the 1mm screen 59 at the top of the screen hopper 60 to remove impurities and sand with excessive particle size. The screened medium sand 61 falls naturally into the electronic scale 62 below. After the electronic scale 62 shows that the weight meets the standard, the feeding into the screen hopper 60 is stopped, completing the accurate measurement of the filling sand of a single sand box. After that, the sand box preparation operation is carried out. First, C30 concrete 64 is poured into the inner cavity of the upper sand cylinder 63; then, the screened medium sand 61 that meets the weight standard is evenly loaded into the lower sand cylinder 68 of the sand box to ensure that the sand is densely filled; after the concrete reaches the design strength, the upper sand cylinder 63 and the lower sand cylinder 68 are assembled accordingly, and lubricating grease 67 is evenly injected into the gap between the upper sand cylinder 63 and the lower sand cylinder 68 to form a sealing and friction-reducing layer to reduce the frictional resistance during subsequent unloading. Subsequently, the bottom steel plate 69 and the steel pipe column 70 are welded and fixed using a full welding method. After the connection is stable, the corresponding construction is carried out above the upper sand cylinder 63. Finally, the opening size of the sliding steel baffle 66 at the sand unloading window 65 is controlled according to the unloading speed requirements, so that the screened medium sand 61 in the lower sand cylinder 68 flows out at a uniform speed, realizing precise unloading control of the sand box. After the support unloading operation is completed, the sand unloading window 65 is closed and the sliding steel baffle 66 is fixed, completing the entire high-efficiency sand box loading and unloading construction process.

[0083] In this embodiment, as Figure 1 As shown, in the construction of the flange plate shaped keel frame support, the installation points of the disc-lock scaffold uprights 6 are first accurately marked in the flange plate area 2. The uprights 6, horizontal bars 18, and diagonal braces 7 are then installed sequentially using a hoisting device. Disc-lock top supports 3 are installed on the top of the uprights 6, and the first I-beam 17 is placed there, thus completing the lower disc-lock scaffold load-bearing foundation. Subsequently, the shaped keel frame support system is installed, and the uprights 6, vertical supports 12, and the horizontal steel pipes 5 and longitudinal steel pipes 4 of the disc-lock scaffold are connected and fixed using steel pipe couplers 15. This forms a stable truss structure. At the same time, the inner end of the bottom channel steel 16 is erected above the outer formwork base plate 10 to enhance the stress coordination performance. Next, positioning bars 9 are arranged above the top channel steel 14. The positioning bars 9 are used to assist in laying the timber 8 to ensure the laying accuracy. Then, the flange template 19 is installed, and measuring points 11 are set at the corresponding positions of the top channel steel 14 and the vertical support 12 to monitor the deformation status of the support system in real time. Finally, the working platform 1 is erected at the tail of the top channel steel 14 to create a safe operating area for on-site operations.

[0084] like Figures 2-4As shown, in the construction of the sliding inner formwork of the box girder 20 box chamber 21, the inner formwork base plate 27 is first placed at the bottom of the box chamber, the supporting steel pipe 28 is installed, and the I-beam rail 37 and the second I-beam 38 are laid to complete the bottom support structure. Then, the middle stable support system is built, the first hydraulic support rod 39, the second hydraulic support rod 36 and the top seat 35 are installed, and the steel support 30, angle steel diagonal brace 29 and angle steel horizontal brace 34 are connected and reinforced to ensure the rigidity and stability of the support. Next, the inner formwork system is assembled. The steel panel 24, steel strip 23, inner formwork channel steel 25 and other components are assembled in sections by using the hinge plate 31, connecting bolt 26 and fixed plate 33. The adjustable screw rod 32 is used to finely adjust the spatial position of the inner formwork so that the steel panel 24 is precisely fitted to the inner wall 41 of the box chamber and spliced ​​with the inner formwork base plate 27. First, fix the inner formwork of the current segment to facilitate the cast-in-place operation. Then, after the cast-in-place operation is completed, prepare for sliding. First, extend and reinforce the I-beam rail 37, release the connecting bolts 26 between the formworks, remove the adjustable screw rods 32 on the side and retract the side formwork. Temporarily support it with the first hydraulic support rod 39, remove the second hydraulic support rod 36 and replace it with the formwork moving trolley 43. Use the formwork moving trolley 43 to slide the main body of the inner formwork system to the next position. If there is a variable cross section 40, remove the bottom chamfered formwork 42 and move it separately. Finally, after sliding into place, remove the formwork moving trolley 43 and replace the second hydraulic support rod 36. Install the bottom chamfered formwork 42 and fine-tune the position of the inner formwork according to the size of the box girder using the adjustable screw rods 32 to ensure that the steel panel 24 fits the box wall. Repeat the formwork support and moving steps to complete the construction of all beams.

[0085] like Figures 5-7 As shown, during the concrete leveling and grouting construction of the top slab 47 of the wide-span cast-in-place box girder, the bottom slab 50, side webs 49, and middle webs 48 are first poured. After the lower concrete reaches the required strength, the paver track 52 is erected based on the inner rail steel support 55 pre-embedded during the pouring of the middle web 48. Subsequently, the outer paver track 52 is supported by the top support 53 and the rail steel support 55. The outer rail steel support 55 is connected to the guardrail steel cage 54 at the top and to the top slab 47 steel reinforcement at the bottom. The inner common track is laid on the rail steel support 55 pre-embedded in the middle web 48, and its upper part is connected to the top slab 47 steel reinforcement and the divider steel cage 58 to ensure the stability of the track system. Then, the left track is laid out in sections above the top slab 47. The left and right laser pavers 44 and 45 are positioned so that their walking mechanisms 51 are placed on the paver track 52. The elevation acquisition accuracy of the laser sensor 46 and the linkage performance between the telescopic mechanism 56 and the paving slab 57 are then tested. Subsequently, the top slab concrete is poured. Then, the laser sensor 46 provides real-time elevation data, and the laser paver walking mechanism 51 moves synchronously along the track to perform slurry leveling. The control system adjusts the position of the paving slab 57 through the telescopic mechanism 56 to precisely control the flatness. Finally, the paver system is shut down, and the flatness and elevation of the top slab surface are checked. After confirming that it meets the design requirements, the left and right laser pavers 44 and 45, as well as the paver track 52, are removed, completing the slurry leveling construction.

[0086] like Figure 8 , Figure 9 As shown, during the sand box loading and unloading process, the sand screening and weighing operations are carried out first. The filling sand is poured into the sieve 60 with a 1mm screen 59 to remove impurities and sand particles exceeding the standard size. The medium sand 61 after screening falls into the electronic scale 62 below. The feeding is stopped after the weight reaches the standard, completing the accurate measurement of the filling sand for a single sand box. Then, the sand box is prepared. C30 concrete 64 is poured into the inner cavity of the upper sand cylinder 63. The medium sand 61 after screening is evenly loaded into the lower sand cylinder 68 and compacted. After the concrete reaches the design strength, the upper sand cylinder 63 and the lower sand cylinder 68 are installed accordingly. First, lubricant 67 is evenly injected into the gap between the two to form a sealing and friction-reducing layer. Then, the bottom steel plate 69 at the bottom of the lower sand cylinder 68 is welded and fixed to the steel pipe column 70 by full welding to ensure a stable connection. Then, the corresponding construction is carried out above the upper sand cylinder 63. Finally, according to the unloading speed requirements of the support, the opening size of the sliding steel baffle 66 at the sand unloading window 65 is adjusted so that the screened medium sand 61 in the lower sand cylinder 68 flows out at a uniform speed to achieve precise unloading. After the unloading operation is completed, the sand unloading window 65 is closed and the sliding steel baffle 66 is fixed to complete the entire construction process.

[0087] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this invention falls within the protection scope of this invention.

Claims

1. A construction method for ultra-wide variable cross-section multi-cell cast-in-place box girders, characterized in that, Includes the following steps: Flange plate support construction: Set up a lower disc buckle bracket in the flange plate area (2) and install a fixed keel frame support system on the disc buckle bracket; connect the fixed keel frame support system with the disc buckle bracket through steel pipe fasteners (15) to form a truss structure; set up positioning ribs (9) above the top channel steel (14) of the fixed keel frame support system to assist in laying timber (8). Construction of the inner mold of the box: A sliding inner mold system (22) is used in the box (21) area. The spatial position of the inner mold is finely adjusted by the adjustable screw (32) to match the inner wall (41) of the box; the sliding inner mold system (22) is moved on the I-beam rail (37) by the mold moving trolley (43); when the construction reaches the position of the variable cross section (40), the bottom chamfer mold (42) in the sliding inner mold system (22) is removed and moved separately; Top slab leveling construction: During the pouring of the middle web (48), the inner rail steel support (55) for supporting the inner paver track (52) is pre-embedded simultaneously; after the middle web (48) and side web (49) are poured, the inner paver track (52) and outer paver track (52) are erected; laser pavers (44, 45) are deployed, and elevation data is collected through laser sensors (46) to level the top slab (47) of the wide box girder; the laser pavers (44, 45) A left-side laser paver (44) and a right-side laser paver (45) are respectively arranged along both sides of the top plate (47) and are located on the inner side paver track (52) on the inner side; the outer side paver track (52) is fixed by an outer side rail steel support (55), the upper part of which is connected to the guardrail steel cage (54); the laser paver controls the telescopic mechanism (56) to adjust the position of the paving plate (57) based on the data fed back by the laser sensor (46); Sand box unloading construction: When preparing the sand box, a 1mm sieve (59) is used to screen the filling sand, and an electronic scale (62) is used to weigh the medium sand (61) after screening. Then the medium sand (61) after screening is loaded into the lower sand cylinder (68). When the support is unloaded, the opening size of the sand unloading window (65) is adjusted by controlling the push-pull steel baffle (66) to control the flow of the medium sand (61) after screening.

2. The construction method according to claim 1, characterized in that, During the construction of the flange plate support: the fixed keel support system includes vertical bracing (12), diagonal bracing (13), top channel steel (14) and bottom channel steel (16); a part of the bottom channel steel (16) is erected above the outer formwork base plate (10); measuring points (11) are set on the top channel steel (14) and vertical bracing (12).

3. The construction method according to claim 1, characterized in that, During the construction of the inner mold of the box: the sliding inner mold system (22) connects the segments through the hinge plate (31), connecting bolts (26) and fixed plate (33); before sliding, the first hydraulic support rod (39) is used for temporary support, the second hydraulic support rod (36) is retracted and removed, and then replaced with the mold moving trolley (43); after sliding into place, the mold moving trolley (43) is removed and the second hydraulic support rod (36) is replaced.

4. The construction method according to claim 1, characterized in that, During the sand box unloading operation: the sand box also includes an upper sand cylinder (63), the inner cavity of which is filled with C30 concrete (64); grease (67) is injected into the gap between the upper sand cylinder (63) and the lower sand cylinder (68).

5. A construction system for implementing the construction method according to any one of claims 1-4, characterized in that, include: Flange plate shaped keel frame support system: suitable for installation on the lower disc buckle bracket, and suitable for connection with the disc buckle bracket through steel pipe fastener (15) to form a truss structure; the shaped keel frame support system includes a top channel steel (14), and a positioning rib (9) is provided above the top channel steel (14). The sliding inner mold system (22) includes an adjustable lead screw (32) suitable for fine-tuning the spatial position of the inner mold, an I-beam rail (37) suitable for carrying the sliding inner mold system (22) to slide, and a mold moving trolley (43); the sliding inner mold system (22) includes a detachable bottom chamfering mold (42); Wide box girder top slab leveling system: includes an inner rail steel support (55) for supporting the inner paver track (52) and adapted to be embedded in the middle web plate (48), the inner paver track (52), the outer paver track (52), and laser pavers (44, 45) mounted on the tracks, the laser pavers being equipped with laser sensors (46); the laser pavers include a left laser paver (44) and a right laser paver (45), both adapted to be located together on the inner side. On the paver track (52), the outer side is located on the corresponding outer paver track (52); the system also includes a track steel support (55) for fixing the outer side of the outer paver track (52), the outer track steel support (55) being adapted to connect the guardrail steel cage (54); the laser paver also includes a telescopic mechanism (56) and a paving plate (57), the telescopic mechanism (56) being adapted to adjust the position of the paving plate (57) according to the data fed back by the laser sensor (46); Sand box: includes a lower sand cylinder (68) and a push-pull steel baffle (66) for controlling the opening size of the sand discharge window (65) at the lower sand cylinder (68); the system also includes a 1mm sieve (59) for screening the filling sand and an electronic scale (62) for weighing the medium sand (61) after screening.

6. The system according to claim 5, characterized in that, The flange plate shaping keel support system also includes: Vertical bracing (12), diagonal bracing (13) and bottom channel steel (16); the bottom channel steel (16) is suitable for being erected above the outer formwork base plate (10); measuring points (11) are provided on the top channel steel (14) and the vertical bracing (12).

7. The construction system according to claim 5, characterized in that, The sliding inner mold system (22) also includes: The system includes a hinge plate (31), connecting bolts (26), and a fixed plate (33) for connecting segments; the system also includes a first hydraulic support rod (39) and a second hydraulic support rod (36), the second hydraulic support rod (36) being adapted to be replaced by the mold moving trolley (43) for sliding.

8. The construction system according to claim 5, characterized in that, The sandbox also includes: The upper sand cylinder (63) is filled with C30 concrete (64) in its inner cavity; the gap between the upper sand cylinder (63) and the lower sand cylinder (68) is filled with grease (67).

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