A side span closure construction method for a double-tower cable-stayed bridge

Abstract

The present application discloses a side span closure construction method for a double-tower cable-stayed bridge, comprising the following steps: S1, after the construction of the first approaching segment is completed, S2, the front end inclined cable is released, and the hanging basket is moved to the second approaching segment; S3, the closing segment hanger and the rigid frame are installed, and then the closing segment box girder is hoisted between the two first approaching segments; S4, temporary rigid connection is constructed, and cast-in-place segment brackets, closing segment templates, and steel bars are constructed; S5, the closing segment concrete is poured and maintained; S6, prestressing, pressure drop, and anchor sealing; S7, the side span closing hanger, temporary rigid connection, and cast-in-place segment bracket are removed; S8, iron sand concrete counterweight is placed in the box; S9, prestressing of the closing segment is tensioned. Before hoisting the closing section box girder, install the closing section hanger and rigid frame. After the closing section box girder is hoisted, construct a temporary rigid connection, and construct the cast-in-place section bracket, closing section formwork, and steel bars to improve the connection strength between the closing section and the first closing section and reduce the possibility of cracking.

Description

Technical Field

[0001] The present application relates to the technical field of suspension bridge construction, and in particular to a side span closure construction method for a double-tower cable-stayed bridge. Background Art

[0002] The double-tower cable-stayed bridge adopts tower-pier consolidation, tower-beam separation, and semi-floating system prestressed concrete main beam. The main bridge is located on a straight line, and the tower-beam is temporarily consolidated during the main beam construction.

[0003] During construction, construction is generally carried out from both sides simultaneously towards the middle, and finally the beam is closed. During the construction of the closing section, due to the influence of factors such as the dead weight of concrete, temperature changes, and construction loads, the two cantilever ends of the main beam at the closing section are prone to relative displacement and rotation, which can easily lead to cracks at the connection between the beam sections. Summary of the invention

[0004] The purpose of the present application is to provide a method for the joint construction of the side spans of a double-tower cable-stayed bridge, so as to improve the problem that the high-altitude construction of the tie beam is relatively troublesome and has high safety hazards.

[0005] The present application provides a method for closure construction of a side span of a double-tower cable-stayed bridge, which adopts the following technical solution: A method for closure construction of a side span of a double-tower cable-stayed bridge comprises the following steps: S1. After the construction of the first approaching section is completed, S2, release the front end inclined cable and move the hanging basket to the second approaching section; S3, installing the closing section hanger and the rigid frame, and then hoisting the closing section box girder between the two first closing sections; S4. Construct temporary rigid connections, and construct cast-in-place brackets, closed section formwork, and steel bars; S5, pouring and curing of concrete at the closing section; S6, prestressing, pressure drop, anchor sealing; S7. Remove the side span closing hangers, temporary rigid connections, and cast-in-place brackets; S8, iron sand concrete counterweight in the box; S9. Prestressing of closing section.

[0006] By adopting the above technical solution, before hoisting the closing section box girder, the linearity is adjusted first, the closing section hanger and the rigid frame are installed, and after the closing section box girder is hoisted, a temporary rigid connection is constructed, and the cast-in-place section bracket, closing section formwork, and steel bars are constructed, thereby improving the connection strength between the closing section and the first closing section and reducing the possibility of cracking.

[0007] Optionally, in step S4, the closing section includes a left box, a middle top plate and a right box connected in sequence, and the temporary rigid connection includes an inner support and an outer support, the inner support is arranged in the left box and the right box, including two I-36 steel sections arranged in the left box and the right box respectively; the outer support is arranged in the middle box top plate, and a 50*70cm steel plate is pre-embedded on the top surface of the middle box top plate, with 4 pieces pre-embedded in each of the left and right panels, for a total of 8 pieces.

[0008] Optionally, after the installation of the closing section hanger is completed and before adjusting the bottom form linearity, a counterweight needs to be placed at one end of the closing section cantilever, and the weight of the counterweight should be half of the weight of the concrete of the closing section.

[0009] Optionally, in step S4, when constructing steel bars, including longitudinal steel bar joints and steel bar welded joints between beam sections, the longitudinal steel bar joints between beam sections are connected by lap welding, the number of joints in the same connection section shall not exceed 50%, the length of the steel bar welded joint connection section shall not be less than 500 mm, and the reserved joint steel bars shall be arranged alternately in length.

[0010] Further, in step S3, the box girder of the closure section is positioned by means of a hanger.

[0011] Optionally, the hanger includes a support frame and a positioning plate, wherein two support frames are provided and are respectively located on two first closing segments, the positioning plate is provided between the two support frames and can move relative to the support frames in a vertical direction, and two positioning inclined plates are provided on the positioning plate, and the two positioning inclined plates are arranged to support each other to realize the positioning of the closing section box girder along the width direction.

[0012] Through the above technical scheme, when hoisting the closing section box girder, the closing section box girder is hoisted above the positioning plate, and then the closing section box girder is lowered, and the bottom of the closing section box girder gradually contacts with the two positioning inclined plates, thereby realizing the positioning of the closing section box girder along the width direction and improving the assembly accuracy.

[0013] Optionally, a slide plate is connected to the side wall of the positioning plate, a slide rail is provided on the side wall of the support frame, the slide plate slides in the slide rail, a limit stop is provided on the top of the slide plate, and the bottom surface of the limit stop is in contact with the top surface of the slide rail.

[0014] By adopting the above technical solution, the positioning plate can not only realize the positioning of the closing section box girder, but also provide temporary support for the closing section box girder.

[0015] Optionally, a fixed block is fixedly connected to the side wall of the positioning plate, and each of the skateboards is correspondingly provided with two fixed blocks. The skateboard is arranged between the two fixed blocks. Slide grooves are provided on the two side walls of the skateboard, and a slider slides in the slide groove. A slot for inserting the slider is provided on the side wall of the fixed block, and a compression spring is provided between the two sliders.

[0016] By adopting the above technical solution, the detachable connection between the slide plate and the positioning plate is achieved through the arrangement of the slider, the compression spring and the slot.

[0017] Optionally, opposite ends of the two sliding blocks are respectively connected to a first pull rope, the two first pull ropes are connected to the same second pull rope, and one end of the second pull rope away from the first pull rope extends out of the top surface of the slide plate and is connected to a pull ring.

[0018] Through the above technical solution, by providing the pull ring, the first pull rope and the second pull rope, it is convenient to release the connection between the slide plate and the positioning plate, and to take the slide plate away.

[0019] Optionally, two ends of the positioning plate are connected to the left box and the right box respectively by bolts.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. Before hoisting the box girder of the closing section, first adjust the linearity, install the closing section hanger and the rigid frame, and after the box girder of the closing section is hoisted, construct a temporary rigid connection, and construct the cast-in-place section bracket, closing section formwork, and steel bars to improve the connection strength between the closing section and the first closing section and reduce the possibility of cracking; 2. When hoisting the box girder of the closure section, hoist the box girder of the closure section above the positioning plate, then lower the box girder of the closure section, and gradually make the bottom of the box girder of the closure section contact with the two positioning inclined plates, thereby realizing the positioning of the box girder of the closure section along the width direction and improving the assembly accuracy; 3. The slide plate and the positioning plate are detachably connected by means of the slider, the compression spring and the card slot; 4. The pull ring, the first pull rope and the second pull rope are arranged to facilitate releasing the connection between the slide plate and the positioning plate, and facilitate taking away the slide plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flowchart showing the overall construction method of the side span closure of a double-tower cable-stayed bridge.

[0022] Figure 2 It is a schematic diagram of a support frame in the present invention.

[0023] Figure 3 It is a three-dimensional schematic diagram of a positioning plate in the present invention.

[0024] Figure 4 The figure is a schematic cross-sectional view showing the connection between the sliding plate and the fixing block in the present invention.

[0025] In the figure, 1, support frame; 11, slide rail; 2, positioning plate; 21, bottom plate; 22, positioning inclined plate; 23, middle plate; 24, slide plate; 241, limit stop block; 242, slider; 243, compression spring; 244, first pull rope; 245, second pull rope; 246, pull ring; 25, fixing block; 3, first approaching section; 4, second approaching section; 5, closing section box girder; 51, left box; 52, right box; 53, middle top plate. DETAILED DESCRIPTION

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Embodiment 1 A construction method for the side span closure of a double-tower cable-stayed bridge, referring to Figures 1 to 4 , including the following steps: S1. The first approaching segment 3 is constructed by hanging a basket. There are two first approaching segments 3, namely, the stage closest to the closing segment.

[0029] S2, release the front end inclined cable and move the hanging basket to the second approaching segment 4, which is the stage adjacent to the first approaching segment 3.

[0030] S3, installing the closing section hanger and the rigid frame, and then hoisting the closing section box beam 5 between the two first closing sections 3. The closing section box beam 5 includes a left box 51, a middle top plate 53 and a right box 52 which are connected in sequence.

[0031] The hanger includes a support frame 1 and a positioning plate 2. There are two support frames 1, which are respectively located on two first closing segments 3. The positioning plate 2 is arranged between the two support frames 1 and can move relative to the support frame 1 in the vertical direction. Two positioning inclined plates 22 are arranged on the positioning plate 2. The two positioning inclined plates 22 are arranged in opposition to each other and are used to abut against the left box 51 and the right box 52 to achieve the positioning of the adjacent closing segments along the width direction.

[0032] There is a certain gap between the first approaching segment 3 and the closing segment box beam 5 when the seam is not sealed, which can accommodate the slide plate 24.

[0033] The positioning plate 2 includes two bottom plates 21, two positioning inclined plates 22 and an intermediate plate 23. The two bottom plates 21 are used to contact the bottom surfaces of the left box 51 and the right box 52, and are connected to the left box 51 and the right box 52 respectively by bolts. When hoisting the closed section box girder 5, the closed section box girder 5 is hoisted above the positioning plate 2, and then the closed section box girder 5 is lowered, and the bottom of the closed section box girder 5 gradually contacts the two positioning inclined plates 22, thereby realizing the positioning of the closed section box girder 5 along the width direction and improving the assembly accuracy.

[0034] A slide plate 24 is connected to the side wall of the positioning plate 2, and a slide rail 11 is provided on the side wall of the support frame 1. The slide plate 24 slides in the slide rail 11, and a limit stopper 241 is provided on the top of the slide plate 24, and the bottom surface of the limit stopper 241 contacts the top surface of the slide rail 11.

[0035] A fixing block 25 is fixedly connected to the side wall of the positioning plate 2, and two fixing blocks 25 are correspondingly provided for each slide plate 24. The slide plate 24 is arranged between the two fixing blocks 25. Slide grooves are provided on the two side walls of the slide plate 24, and a slider 242 slides in the slide groove. A card slot for the slider 242 to be inserted is provided on the side wall of the fixing block 25, and a compression spring 243 is provided between the two sliders 242. The detachable connection between the slide plate 24 and the positioning plate 2 is achieved by setting the slider 242, the compression spring 243 and the card slot.

[0036] The opposite ends of the two sliders 242 are respectively connected to a first pull rope 244 , and the two first pull ropes 244 are connected to the same second pull rope 245 . The end of the second pull rope 245 away from the first pull rope 244 extends out of the top surface of the slide plate 24 and is connected to a pull ring 246 .

[0037] By providing the pull ring 246 , the first pull rope 244 and the second pull rope 245 , it is convenient to release the connection between the slide plate 24 and the positioning plate 2 , and to remove the slide plate 24 .

[0038] S4. Construct temporary rigid connection, and construct cast-in-place bracket, closing section formwork, and steel bars, and then remove the slide plate 24 and support frame 1. The temporary rigid connection includes internal support and external support. The internal support is set in the left box 51 and the right box 52, including two I-36 steels set in the left box 51 and the right box 52; the external support is set in the middle box top plate, and the top surface of the middle box top plate is pre-embedded with 50*70cm steel plates, and 4 pieces are pre-embedded in the left and right sections, totaling 8 pieces.

[0039] Anchoring pre-embedded steel bars are added around the embedded parts to strengthen the anchoring. Before the side span closure construction, the steel rigid skeleton anchored on both sides of the closure section is used as a rigid connection to temporarily lock the closure section. After the longitudinal prestressing of the side span closure is completed, the temporary lock of the closure section is released. When dismantling, pay attention to sealing the embedded parts after cutting to prevent rust.

[0040] When constructing steel bars, including longitudinal steel bar joints and steel bar welded joints between beam sections, the longitudinal steel bar joints between beam sections are connected by lap welding. The number of joints in the same connection section shall not exceed 50%. The length of the steel bar welded joint connection section shall not be less than 500mm, and the reserved joint steel bars shall be arranged alternately of long and short lengths.

[0041] The order of steel bar installation is as follows: install the bottom formwork of the closing section → tie the lower layer of steel bars and stirrups of the side box bottom plate 21 → install the prestressed pipe positioning steel bars and the bottom plate 21 corrugated pipe → tie the upper layer of steel bars and the web steel bars of the bottom plate 21 → tie the top plate steel bars, and simultaneously install the prestressed pipe positioning steel bars and corrugated pipes → install the top plate tension bars.

[0042] During the installation of steel bars, they need to be properly shifted and reinforced. The specific situations are as follows: when the steel bars collide with the prestressed pipe, the steel bars are properly shifted or bent for reinforcement; when the reserved holes such as the ventilation holes and drainage holes of the beam body collide, the steel bars are properly shifted or disconnected, and spiral bars are added near the reserved holes; when the prestressed pipe collides with the reserved holes, the position of the reserved holes is properly moved.

[0043] S5. Pour concrete and maintain the closing section.

[0044] S6, prestressing, pressure drop, and anchor sealing.

[0045] S7. Remove the side span closing hangers, temporary rigid connections, and cast-in-place section brackets.

[0046] S8. Iron sand concrete counterweight in the box.

[0047] After the installation of the closing section hanger is completed and before adjusting the bottom formwork linearity, a counterweight is required at one end of the closing section cantilever. The weight of the counterweight should be half of the weight of the concrete in the closing section.

[0048] Taking the side span closure section as an example, the required counterweight weight is 67.5*0.5*2.4=81t. Standard concrete counterweights are used on site. The concrete counterweights have a structural size of 1.5*1*1m and a single counterweight weighs 3.7t. The number of counterweights required is 81 / 3.7=22.

[0049] The width of the main beam is 28.5m, and the available counterweight width on the beam surface is 2*3.75*2+1.5=16.5m. The counterweight is considered to be 15m wide. The counterweight blocks are arranged horizontally at the 1.5m position at the end of the closing section. 15 counterweight blocks can be placed on each layer, and 2 layers are placed. It is also possible to reserve sufficient construction space according to the actual situation on site and arrange the counterweight blocks in an evenly stacked manner, with a maximum of no more than 3 layers.

[0050] After the counterweight block is configured, linear monitoring is carried out and the bottom formwork elevation is adjusted, the temporary skeleton is locked, and the steel bars and prestressing are installed. When the concrete is poured, the counterweight block is unloaded simultaneously. The counterweight block is unloaded by means of truck crane transportation. The weight of a single counterweight block is 3.7t, and the total concrete is 1.5m³. Other forms of counterweights can also be selected on site according to the weight of the counterweight required, such as water tank counterweights, but the principle of unloading the same amount as the amount poured should be followed.

[0051] S9. Prestressing of closing section.

[0052] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for closure construction of a side span of a double-tower cable-stayed bridge, characterized in that: The steps include: S1, constructing the first approaching section (3) by means of a hanging basket; S2, releasing the front end inclined cable and moving the hanging basket to the second approaching section (4); S3, installing the closing section hanger and the rigid frame, and then hoisting the closing section box girder (5) between the two first closing sections (3); S4. Construct temporary rigid connections, cast-in-place brackets, closed-section formwork, and reinforcement; S5, pouring and curing of concrete at the closing section; S6, prestressing, pressure drop, anchor sealing; S7. Remove the side span closing hangers, temporary rigid connections, and cast-in-place brackets; S8, iron sand concrete counterweight in the box; S9. Prestressing of closing section.

2. A method for closure construction of a side span of a double-tower cable-stayed bridge according to claim 1, characterized in that: In step S4, the folded section box girder (5) includes a left box (51), a middle top plate (53) and a right box (52) connected in sequence, and the temporary rigid connection includes an inner support and an outer support. The inner support is arranged in the left box (51) and the right box (52), and includes two I-36 steel sections arranged in the left box (51) and the right box (52); the outer support is arranged in the middle box top plate, and a 50*70cm steel plate is embedded in the top surface of the middle box top plate, and 4 pieces are embedded in each of the left and right widths, for a total of 8 pieces.

3. The side span closure construction method of a double-tower cable-stayed bridge according to claim 1 is characterized by: After the installation of the closing section hanger is completed and before adjusting the bottom formwork linearity, it is necessary to place a counterweight at one end of the closing section cantilever. The weight of the counterweight should be half of the weight of the concrete in the closing section.

4. The side span closure construction method of a double-tower cable-stayed bridge according to claim 2, characterized in that: In step S4, when constructing steel bars, including longitudinal steel bar joints and steel bar welded joints between beam sections, the longitudinal steel bar joints between beam sections are connected by lap welding, the number of joints in the same connection section does not exceed 50%, the length of the steel bar welded joint connection section is not less than 500 mm, and the reserved joint steel bars are arranged alternately in length.

5. The side span closure construction method of a double-tower cable-stayed bridge according to claim 4 is characterized in that: In step S3, the closing section box girder (5) is positioned by means of a hanger.

6. A method for closure construction of a side span of a double-tower cable-stayed bridge according to claim 5, characterized in that: The hanger comprises a support frame (1) and a positioning plate (2), wherein two support frames (1) are provided and are respectively located on two first closing segments (3), wherein the positioning plate (2) is provided between the two support frames (1) and is movable relative to the support frame (1) in a vertical direction, wherein two positioning inclined plates (22) are provided on the positioning plate (2), and the two positioning inclined plates (22) are arranged to support each other so as to realize the positioning of adjacent closing segments along the width direction.

7. The side span closure construction method of a double-tower cable-stayed bridge according to claim 6, characterized in that: A slide plate (24) is connected to the side wall of the positioning plate (2), a slide rail (11) is provided on the side wall of the support frame (1), the slide plate (24) slides in the slide rail (11), a limit stop block (241) is provided on the top of the slide plate (24), and the bottom surface of the limit stop block (241) contacts the top surface of the slide rail (11).

8. The side span closure construction method of a double-tower cable-stayed bridge according to claim 7, characterized in that: A fixed block (25) is fixedly connected to the side wall of the positioning plate (2), and each of the slide plates (24) is correspondingly provided with two fixed blocks (25). The slide plate (24) is arranged between the two fixed blocks (25). Slide grooves are provided on the two side walls of the slide plate (24), and a slider (242) slides in the slide groove. A slot for inserting the slider (242) is provided on the side wall of the fixed block (25), and a compression spring (243) is provided between the two sliders (242).

9. The side span closure construction method of a double-tower cable-stayed bridge according to claim 8, characterized in that: The opposite ends of the two sliding blocks (242) are respectively connected to a first pull rope (244), and the two first pull ropes (244) are connected to the same second pull rope (245). The end of the second pull rope (245) away from the first pull rope (244) extends out of the top surface of the sliding block (24) and is connected to a pull ring (246).

10. The side span closure construction method of a double-tower cable-stayed bridge according to claim 8, characterized in that: The two ends of the positioning plate (2) are connected to the left box (51) and the right box (52) respectively by bolts.

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