Formwork system for prefabricating concrete bridge deck slab through long-line method and construction method

Abstract

The invention relates to the technical field of bridge construction, and provides a formwork system and a construction method.The formwork system comprises a bottom formwork and a side formwork, the side formwork comprises an upper plate body and a lower plate body, and the upper plate body and the lower plate body are detachably connected; comb tooth grooves are formed in the involution faces of the upper plate body and the lower plate body respectively, when the upper plate body and the lower plate body are connected in an involution mode, the comb tooth grooves in the upper plate body and the comb tooth grooves in the lower plate body are involution and jointly define long-strip-shaped positioning holes, and the arrangement positions of the long-strip-shaped positioning holes in the side mold are matched with the positions of main reinforcements on a steel reinforcement framework. And main reinforcements of the steel reinforcement framework are all positioned and mounted in the long-strip-shaped positioning holes. The overall positioning advantage of a long-line method and forced positioning of positioning holes in side plates are combined, the bridge site space relation is accurately reproduced in the prefabrication stage, and millimeter-level butt joint positioning of large-diameter and high-density steel bars is achieved; the innovative structural design of the side plates ensures local rigidity and quick and lossless demolding.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a formwork system and construction method for long-line precast concrete bridge decks. Background Technology

[0002] Precast concrete bridge decks are widely used in railway and highway bridge construction due to their ease of quality control and rapid construction. However, traditional bridge decks often employ a segmented, independent precasting method. Because each panel is independently supported, cumulative errors are difficult to eliminate, and the three-dimensional spatial relationships (such as curvature, slope, and angles) between adjacent panels during installation cannot be accurately simulated during the precast stage. This leads to frequent problems such as interference between main reinforcement bars and misaligned joints during on-site splicing of precast bridge decks, especially in cases with large-diameter, densely arranged reinforcement bars. Construction workers are forced to perform extensive on-site cutting, bending, and adjustments, which not only consumes significant manpower and resources and extends the construction period but also potentially damages the structural integrity and durability. While existing technologies include methods for batch precasting using fixed platforms, there is a lack of effective systematic solutions for ensuring the matching and positioning of reinforcement bars between multiple panels. To improve accuracy, formwork using comb-tooth plates for positioning reinforcement bars has emerged, but these are mostly integral structures. When attempting to apply such comb-tooth plates to long-line construction, new technical barriers were encountered: the long-line method requires continuous operation on a platform tens to hundreds of meters long, resulting in large and uneven lateral pressure on the concrete. The rigidity of the integral thin-plate comb-tooth plate is insufficient, making it prone to warping and deformation, which leads to inaccurate positioning of the pre-set holes. More seriously, after pouring, the steel bars and concrete "lock" the integral comb-tooth plate, making demolding difficult, easily damaging the components, and resulting in low formwork turnover efficiency. Summary of the Invention

[0003] This invention provides a template system and installation method for precast concrete bridge deck using the long-line method. Combining the overall positioning advantages of the long-line method with the forced positioning of positioning holes on the side plates, it accurately reproduces the spatial relationship of the bridge site during the precast stage, achieving millimeter-level docking positioning of large-diameter, high-density steel bars. The side plates adopt an "upper and lower split bolted connection" structure, which can ensure local rigidity and achieve rapid and non-destructive demolding through step-by-step demolding.

[0004] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows:

[0005] A formwork system for precast concrete bridge decks using the long-line method includes a bottom formwork and side formwork installed on the bottom formwork. A reinforcing steel skeleton is installed on the side formwork. The side formwork includes an upper plate and a lower plate, which are detachably connected. Comb grooves are respectively opened on the mating surfaces of the upper plate and the lower plate. When the upper plate and the lower plate are mated and connected, the comb grooves on the upper plate and the lower plate align and together form an elongated positioning hole. The arrangement of the elongated positioning hole on the side formwork matches the position of the main reinforcing bars on the reinforcing steel skeleton, so that the main reinforcing bars of the reinforcing steel skeleton are all positioned and installed in the elongated positioning hole.

[0006] The width of the elongated positioning hole is 5mm larger than the nominal diameter of the main reinforcement bar of the steel cage.

[0007] Reinforcing ribs are provided on the outer sides of both the upper and lower plates.

[0008] Flanges are provided on the mating surfaces of the upper and lower plates, and the two are connected by flanges and bolts.

[0009] The upper and lower plates are made of high-strength steel plates with a thickness of 12mm.

[0010] The template system also includes a shear nail groove mold installed on the bottom mold, the panel of which is made of 12mm thick ordinary carbon steel plate.

[0011] The bottom mold includes a panel and vertical ribs and walers supporting the bottom of the panel; the panel is made of stainless steel composite steel plate, the vertical ribs are made of C10 channel steel, and the walers are made of double C18 channel steel.

[0012] A leveling mechanism is provided below the bottom mold; the leveling mechanism includes a jack for lifting and a steel shim for filling the gap between the jack and the bottom mold.

[0013] This invention also provides a construction method for long-line precast concrete bridge decks, comprising the following steps:

[0014] S1: On the long platform, install and level multiple sets of template systems according to the design line of the bridge deck so that the three-dimensional coordinates of the joint surfaces of adjacent template systems are matched.

[0015] S2: The main reinforcement bars of the steel cage are tied and positioned by passing them through the long positioning holes on the side formwork to form the steel cage;

[0016] S3: Apply a grout-proofing system at the joints of the formwork system;

[0017] S4: Pouring concrete;

[0018] S5: After the concrete is formed, first remove the upper plate of the side formwork, and then demold the entire bridge deck.

[0019] The grout-proof system includes a non-scraping grout-stopping strip fixed to the inside of the side formwork and grout filling the gaps in the formwork system.

[0020] Compared with existing technologies, the technical solution provided by this invention has the following advantages: 1. Creatively solves industry problems: The side formwork positions the reinforcing bars through elongated positioning holes, enabling the reinforcing bars of adjacent precast bridge decks to achieve interlocking connections, with the connection deviation controlled within 3mm; at the same time, the elongated positioning holes on the side formwork are of a split bolted structure, and after the concrete is formed, the constraint of the reinforcing bar skeleton is released by removing the upper plate, facilitating the overall demolding of the bridge deck. Meanwhile, the flange connection and reinforcing ribs provide local rigid nodes, and the step-by-step demolding process of "removing the upper plate first and then demolding" avoids damage to the formwork and bridge deck.

[0021] 2. Revolutionary Improvement in Precision and Efficiency: Combining the advantages of the long-line method for overall positioning with the microscopic control capabilities of the positioning holes on the side panels, the spatial relationship between multiple adjacent bridge deck panels at the bridge site is accurately reproduced during the prefabrication stage. This achieves millimeter-level precision positioning of large-diameter, high-density reinforcing bars, fundamentally eliminating on-site reinforcement interference and increasing the on-site installation success rate to over 95%, significantly improving formwork turnover efficiency. This method is suitable for the prefabrication of steel-concrete composite beam bridge decks using the long-line method, with large-diameter reinforcing bars (e.g., φ32mm), dense arrangement, and high precision requirements (e.g., ≤2mm).

[0022] 3. Significant economic benefits: The entire construction method shortens the construction period by reducing on-site adjustments (such as shortening the construction period by a total of 42 days in the Jinzhai Shihe Grand Bridge project) and reduces losses, which can save more than one million yuan in direct costs in large-scale projects.

[0023] 4. Reliable quality and strong applicability: The anti-leakage grouting system ensures the quality of component joints. This system is particularly suitable for the prefabrication of bridge decks with large-diameter, high-density steel reinforcement, and has high promotional value. Attached Figure Description

[0024] Figure 1 This is a front view schematic diagram of the overall layout of the template system provided by the present invention;

[0025] Figure 2 A top view of the overall layout of the template system provided by the present invention;

[0026] Figure 3 This is a schematic diagram of the side mold structure in this invention;

[0027] Figure 4 This is a front view schematic diagram of the formwork system and reinforcement arrangement during the long-line construction method of this invention;

[0028] Figure 5 This is a top view schematic diagram of the formwork system and reinforcement arrangement during the long-line construction method of this invention;

[0029] In the diagram: 1-Upper plate, 2-Lower plate, 3-Elongated positioning hole, 4-Reinforcing rib plate, 5-Bolt, 6-Panel, 7-Vertical rib, 8-Walter, 9-Shear nail slot mold, 10-Flange, 11-Reinforcing steel skeleton. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings.

[0031] The formwork system for the long-line precast concrete bridge deck provided in this embodiment includes a bottom formwork and side forms and shear nail slot formwork 9 installed on the bottom formwork, such as... Figures 1-2 As shown.

[0032] In this embodiment, the bottom formwork includes a panel 6 and vertical ribs 7 and walers 8 supporting the bottom of the panel. The panel is made of stainless steel composite steel plates. The bottom formwork is precision machined according to the design lines of the bridge deck. The vertical ribs are made of C10 channel steel, and the walers are made of double C18 channel steel, ensuring the flatness, durability, and overall rigidity of the bottom formwork. A leveling mechanism is provided below the bottom formwork and is installed on a continuous platform. Specifically, the leveling mechanism includes jacks for lifting and steel shims for filling the gap between the jacks and the bottom formwork. The steel shims can be of various thicknesses and, together with the jacks, ensure precise leveling. The panel of the shear stud slot formwork is made of 12mm thick ordinary carbon steel plate.

[0033] In this embodiment, the side mold includes an upper plate 1 and a lower plate 2, which are detachably connected, such as... Figure 1 and Figure 3As shown; specifically, flanges are provided on the mating surfaces of the upper and lower plates, and the two are connected by flanges 10 and bolts 5 to enhance the rigidity and deformation resistance of the side plates; preferably, the bolts are grade 8.8 and the specifications are M20×70. Specifically, the upper plate, lower plate, and flanges are all made of high-strength steel plates with a thickness of 12mm. Specifically, reinforcing ribs 4 are provided on the outer sides of the upper and lower plates, which work together with the flange connection structure to greatly improve the overall rigidity and deformation resistance of the side formwork under large-scale, uneven loads in the long-line method. A steel reinforcement cage is installed on the side formwork. In this embodiment, comb grooves are respectively opened on the mating surfaces of the upper and lower plates. When the upper and lower plates are mated and connected, the comb grooves on the upper and lower plates align and jointly form an elongated positioning hole 3. The arrangement of the elongated positioning hole on the side formwork matches the position of the main reinforcement on the steel reinforcement cage, so that the main reinforcement of the steel reinforcement cage is positioned and installed in the elongated positioning hole. Based on the position of the main reinforcing bars in the design drawings, corresponding elongated positioning holes are set on the side formwork to ensure accurate installation and positioning of the reinforcing bars. Specifically, the width of the elongated positioning holes is 5mm larger than the nominal diameter of the main reinforcing bars in the reinforcing bar cage, with a design clearance allowing for a fine adjustment of ±2.5mm, thus achieving micro-adjustment under forced positioning. The side formwork positions the reinforcing bars through the elongated positioning holes, enabling the reinforcing bars of adjacent precast bridge decks to achieve an interlocking connection, with the connection deviation controlled within 3mm. Simultaneously, the side formwork is a split bolted structure; after concrete molding, the upper plate is removed to release the constraint of the reinforcing bar cage, facilitating the overall demolding of the bridge deck.

[0034] The template system provided by this invention is used in the construction method of long-line precast concrete bridge decks, comprising the following steps:

[0035] S1: On the continuous platform, install and level multiple sets of template systems according to the bridge deck design lines, such as... Figure 4 and Figure 5 As shown in the figure, there are eight template systems, which match the three-dimensional coordinates of the joint surfaces of adjacent template systems.

[0036] Using total station and other surveying equipment, multiple sets of template systems are simultaneously positioned (including curvature, slope and joint angle) and leveled as a whole to ensure that the three-dimensional coordinates of the joint surfaces at the ends of each panel are accurately matched, laying the geometric foundation for interference-free installation of steel bars;

[0037] The specific leveling operation is achieved through a leveling mechanism, using jacks and steel shims of various thicknesses for fine leveling. For height differences greater than 5mm, the equipment is re-lifted, and for height differences less than 5mm, it is jacked up and filled in place for adjustment, ensuring that the top surface elevation error of the multiple template systems on the entire platform is less than 2mm.

[0038] S2: The main reinforcement bars of the steel reinforcement cage are tied and positioned by passing them through the elongated positioning holes on the side formwork, forming the steel reinforcement cage 11. After the semi-finished steel reinforcement is transported to the site, the main reinforcement bars are strictly inserted into the elongated positioning holes of each side formwork block in sequence and tied (bottom layer first, then top layer; main reinforcement bars first, then structural reinforcement bars). Since all formwork blocks are precisely positioned in three-dimensional space, all steel reinforcement bars naturally form the final connection relationship. The main reinforcement bars are forcibly positioned through the elongated positioning holes to ensure accurate positioning and form a "comb-tooth interlocking" precise connection interface between the main reinforcement bars of adjacent panels.

[0039] S3: Apply double-sided tape to all joints of the formwork system, and then apply the anti-leakage grouting system;

[0040] The grout leakage prevention system includes a no-scraping grout-stopping tape fixed to the inside of the side formwork and grout filling the gaps in the formwork system. Specifically, the no-scraping grout-stopping tape is fixed to the inside of the side formwork with clips. A multi-layered grout leakage prevention system is formed by "double-sided tape + no-scraping grout-stopping tape + grout filling".

[0041] S4: Pour concrete and keep it moist for curing;

[0042] S5: After the concrete has set, loosen the bolts on the side formwork, remove the upper plate of the side formwork, release the main reinforcing bars from the upper plate, and then demold the bridge deck as a whole. By removing the upper plate, the constraint of the reinforcing steel skeleton is released, ensuring that the bridge deck can be demolded quickly and without damage.

[0043] Application Results: This example uses the Jinzhai Shihe Grand Bridge (72+3×132+72m) project, consisting of 98 C60 precast bridge deck panels, as an example. The largest single panel weighs 59 tons, and the nominal diameter of the main reinforcement bars reaches 32mm (rare in China). The required positional accuracy of the reinforcement bars is ≤2mm, and the arrangement density is high. The width of the elongated positioning holes in the side formwork is 37mm. The problem of high-precision matching of large-diameter reinforcement bars was successfully solved through the separate bolting of the side formwork and the comb-tooth structure, thus avoiding reinforcement interference. The on-site installation success rate of the 98 bridge deck panels reached over 95%, and the adjustment time for individual panel reinforcement bars was almost zero. The formwork turnover efficiency was improved by approximately 30%, and the overall construction period was shortened by 42 days, achieving significant quality, safety, and economic benefits.

Claims

1. A formwork system for precast concrete bridge decks using the long-line method, comprising a bottom formwork and side formwork installed on the bottom formwork, wherein a steel reinforcement cage is installed on the side formwork, characterized in that: The side mold includes an upper plate and a lower plate, which are detachably connected. The mating surfaces of the upper plate and the lower plate are respectively provided with comb grooves. When the upper plate and the lower plate are mated and connected, the comb grooves on the upper plate and the lower plate align and together form an elongated positioning hole. The arrangement of the elongated positioning hole on the side mold matches the position of the main reinforcement bars on the steel reinforcement cage, so that the main reinforcement bars of the steel reinforcement cage are all positioned and installed in the elongated positioning hole.

2. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: The width of the elongated positioning hole is 5mm larger than the nominal diameter of the main reinforcement bar of the steel cage.

3. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: Reinforcing ribs are provided on the outer sides of both the upper and lower plates.

4. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: Flanges are provided on the mating surfaces of the upper and lower plates, and the two are connected by flanges and bolts.

5. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: The upper and lower plates are made of high-strength steel plates with a thickness of 12mm.

6. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: The template system also includes a shear nail groove mold installed on the bottom mold, the panel of which is made of 12mm thick ordinary carbon steel plate.

7. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: The bottom mold includes a panel and vertical ribs and walers supporting the bottom of the panel; the panel is made of stainless steel composite steel plate, the vertical ribs are made of C10 channel steel, and the walers are made of double C18 channel steel.

8. The formwork system for long-line precast concrete bridge decks according to claim 1, characterized in that: A leveling mechanism is provided below the bottom mold; the leveling mechanism includes a jack for lifting and a steel shim for filling the gap between the jack and the bottom mold.

9. A method for constructing long-line precast concrete bridge decks using the template system according to claim 1, characterized in that... Includes the following steps: S1: On the long platform, install and level multiple sets of template systems according to the design line of the bridge deck so that the three-dimensional coordinates of the joint surfaces of adjacent template systems are matched. S2: The main reinforcement bars of the steel cage are tied and positioned by passing them through the long positioning holes on the side formwork to form the steel cage; S3: Apply a grout-proofing system at the joints of the formwork system; S4: Pouring concrete; S5: After the concrete is formed, first remove the upper plate of the side formwork, and then demold the entire bridge deck.

10. The construction method for long-line precast concrete bridge decks according to claim 9, characterized in that: The grout-proof system includes a non-scraping grout-stopping strip fixed to the inside of the side formwork and grout filling the gaps in the formwork system.

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