An adjustable prestressed concrete box girder end formwork and reinforcement construction method

Abstract

This invention discloses an adjustable prestressed concrete box girder end formwork and reinforcement construction method. The end formwork includes a flange, a top plate, and a haunch end sealing formwork, and further includes: a web, the web including at least one telescopic plate; an upper transverse connecting plate and a lower transverse connecting plate, the upper transverse connecting plate being used to connect two adjacent flanges, top plates, and haunch end sealing formwork, and the lower transverse connecting plate being used to connect two adjacent webs; a telescopic fixing device, installed on the telescopic plate, for fixing the length of the telescopic plate; and a prestressing duct adjustment device, installed at the upper end of the web and / or between each telescopic plate of the web and / or on the flange, top plate, and haunch end sealing formwork, the prestressing duct adjustment device having a prestressing duct insert with a through hole. This invention can solve the problem of inconsistent formwork tube hole positions corresponding to different prestressing pipes due to displacement of the prestressing duct position on different box girder formwork end faces without changing the formwork.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to an adjustable prestressed concrete box girder end formwork and reinforcement construction method. Background Technology

[0002] With the increasing number of long-span continuous beams, cantilever construction is becoming more and more common. Since box girders are mostly variable cross-section box girders, the height of the end-cap formwork varies for each segment during cantilever casting. Furthermore, as the cantilever casting progresses, the prestressing ducts in the box girder may bend or be anchored at certain sections, resulting in different opening positions and numbers of holes in the end-cap formwork at each section, necessitating frequent formwork replacements. Therefore, it is necessary to design an adjustable end-cap formwork for prestressed concrete box girders to reduce the need for modifications to the end-cap formwork.

[0003] A utility model patent with application number CN202020133653.8 discloses a precast box girder formwork system, including a formwork support, panel reinforcement, box girder reinforcement cage, box girder inner formwork, and box girder top formwork. The tilt angle of the formwork angle adjustment plate is adjusted by the formwork angle adjustment bolts on the formwork bottom support plate, and the adjustment support is placed in the gap between the formwork bottom support plate and the formwork angle adjustment plate. The formwork support is set on the top surface of the formwork angle adjustment plate, and the box girder bottom formwork and box girder side formwork are located on the formwork support. Side formwork adjustment ferrules are set at the joints of the box girder side formwork. Adjustment ferrule pressure plates are set on the outer side walls of the side formwork adjustment ferrules, and the adjustment ferrule pressure plates are firmly connected to the box girder side formwork by bolts.

[0004] The precast box girder formwork system provided by the aforementioned patent can define the spatial positions of the box girder side formwork and top formwork respectively through side formwork pressure rods and top side support rods, and can adjust the tilt angle of the box girder bottom formwork through formwork adjustment bolts, reducing the difficulty of spatial positioning of the box girder side formwork, top formwork, and bottom formwork. However, this precast box girder formwork system does not involve the adjustment of the position and height of the box girder ducts, and cannot solve the problem that the displacement of the prestressed ducts on different box girder formwork end faces leads to inconsistent formwork duct hole positions for different prestressed ducts, thus requiring continuous formwork replacement. Summary of the Invention

[0005] The purpose of this invention is to provide an adjustable prestressed concrete box girder end formwork and reinforcement construction method, aiming to improve the existing box girder formwork system, which cannot solve the problem that the position of the prestressed pipe changes on different box girder formwork end faces, resulting in inconsistent formwork pipe hole positions for different prestressed pipes, thus requiring constant formwork replacement.

[0006] To achieve the above objectives, according to one aspect of the present invention, an adjustable prestressed concrete box girder end formwork is provided, comprising a flange, a top plate, and a haunch-end sealing formwork, and further comprising:

[0007] The web is vertically arranged and includes at least one telescopic plate. The wing plate, top plate, and end cap sealing template are arranged at the upper end of the web.

[0008] The transverse connecting plate includes an upper transverse connecting plate and a lower transverse connecting plate. The upper transverse connecting plate is used to connect two adjacent wing plates, a top plate, and a haunch end sealing template. The lower transverse connecting plate is used to connect two adjacent web plates.

[0009] A telescopic fixing device is installed on the telescopic plate to fix the length of the telescopic plate;

[0010] A prestressed duct adjustment device is installed at the upper end of the web and / or between the expansion plates of the web and / or on the flange, top plate and haunch end sealing template. The prestressed duct adjustment device has a prestressed duct insert, and the prestressed duct insert is provided with a through hole for the prestressed duct in the box girder to pass through.

[0011] Furthermore, it also includes a mounting and fixing device, which is set on the telescopic plate. The mounting and fixing device has a screw that can be turned. Turning the screw can tighten the inner formwork or outer formwork of the cast-in-place box girder set on both sides of the width direction of the telescopic plate.

[0012] Furthermore, the telescopic plate includes a first telescopic plate and a second telescopic plate. A rectangular slot is provided at one end of the second telescopic plate along its length. The rectangular slot is arranged along the length of the second telescopic plate. The first telescopic plate is inserted into the rectangular slot of the second telescopic plate. The thickness of the rectangular slot is the same as the thickness of the first telescopic plate.

[0013] Furthermore, the telescopic fixing device includes a telescopic fixing rod and a telescopic sleeve. The length directions of both the telescopic fixing rod and the telescopic sleeve are the same as the length direction of the telescopic plate on which the telescopic fixing device is located. The telescopic sleeve is fixedly mounted on the second telescopic plate. One end of the telescopic fixing rod is fixedly mounted on the first telescopic plate, and the other end passes through the telescopic sleeve. The wall of the telescopic sleeve is provided with a threaded through hole leading to the interior of the telescopic sleeve. A telescopic fixing screw for fixing the telescopic fixing rod is installed in the threaded through hole.

[0014] Furthermore, the mounting and fixing device also includes a mounting and fixing sleeve, which is fixedly mounted on the telescopic plate. The wall of the hole of the mounting and fixing sleeve is provided with a thread structure that matches the mounting and fixing screw, and the mounting and fixing screw is threaded into the mounting and fixing sleeve.

[0015] Furthermore, the prestressed duct adjustment device also includes a prestressed duct slot plate, which is in the shape of an inverted plate. Slot structures are provided on the plate walls on both sides of the opening of the prestressed duct slot plate, and the prestressed duct insert is inserted into the slot structure of the prestressed duct slot plate.

[0016] Furthermore, the prestressed duct insert includes a variety of prestressed duct inserts with different through hole positions, a variety of prestressed duct inserts with different numbers of through holes, and a variety of prestressed duct inserts with different through hole positions and numbers; the prestressed duct slot plate is provided with threaded through holes leading to its slot structure, and each threaded through hole is provided with a bolt for fixing the prestressed duct insert.

[0017] Furthermore, the prestressed duct insert includes a first prestressed duct insert, a second prestressed duct insert, and a third prestressed duct insert; the first prestressed duct insert has three through holes, and these three through holes are equidistantly arranged along the length direction of the first prestressed duct insert; the second prestressed duct insert has two through holes, and the positions of the two through holes of the second prestressed duct insert correspond one-to-one with the positions of any two adjacent through holes of the three through holes of the first prestressed duct insert; the third prestressed duct insert has one through hole, and the position of this through hole of the second prestressed duct insert corresponds to the position of any one of the through holes of the first prestressed duct insert.

[0018] Furthermore, prestressing duct adjustment devices are provided on the upper end of the web plate, as well as on the wing plates, top plate, and haunch end sealing template on the left and right sides of the upper end of the web plate. Multiple prestressing duct adjustment devices are arranged sequentially along the left-right direction, and the openings of the prestressing duct slot plates of these sequentially arranged left-right prestressing duct adjustment devices are at the upper end. Multiple prestressing duct adjustment devices are arranged sequentially along the upper-low direction on the upper end of the web plate, and the openings of the prestressing duct slot plates of these sequentially arranged upper-low prestressing duct adjustment devices are at the left or right end. The prestressing duct slot plates of these sequentially arranged upper-low prestressing duct adjustment devices are arranged to protrude outwards, so that the sequentially arranged left-right prestressing duct adjustment devices do not affect the insertion of the prestressing duct inserts.

[0019] According to a second aspect of the present invention, a method for reinforcing the end formwork of an adjustable prestressed concrete box girder is provided, comprising the following steps:

[0020] S100, assemble the web plate, transverse connecting plate, wing plate, top plate and haunch end sealing template, adjust the width according to the box girder section, and fix the length of the corresponding telescopic plate through the telescopic fixing device;

[0021] S200. Fabricate and install template panels based on the wing plate, top plate, and haunch end sealing template.

[0022] S300. Install prestressed duct adjustment devices on the web, flange, top plate and haunch end sealing formwork according to the location of the prestressed ducts on the box girder.

[0023] S400. A fixing device is installed on the telescopic plate, the fixing device having a screw-on fixing screw;

[0024] S500, hoist the entire formwork to the section of the cast-in-place box girder, tighten the installation and fixing screws, and press against the inner formwork or outer formwork of the cast-in-place box girder set on both sides of the width direction of the expansion plate to fix the end formwork on the section of the cast-in-place box girder.

[0025] S600. After the pouring is completed, loosen the installation fixing screws, hoist it to the next cast-in-place box girder section, adjust the width and height according to the dimensions of the next cast-in-place box girder section, and fix the length of the corresponding telescopic plate through the telescopic fixing device. Finally, tighten the installation fixing screws.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. The invention can solve the problem of inconsistent template tube hole positions for different prestressing pipes caused by the displacement of prestressing pipe positions on different box girder template end faces without changing the template.

[0028] 2. The web can be composed of multiple telescopic plates arranged vertically. A prestressed duct adjustment device is provided between two adjacent telescopic plates. Since the length of the telescopic plates is adjustable, the height of the prestressed duct adjustment device between the two telescopic plates is adjustable, which can adapt to the displacement and opening of the prestressed duct at a higher position on the web.

[0029] 3. The prestressed duct inserts of the prestressed duct adjustment device have various structures. The difference between the prestressed duct inserts with different structures lies in the number and position of the through holes. By using prestressed duct inserts with different structures, the position and number of through holes can be adjusted, which can adapt to the displacement of the prestressed duct position to a certain extent. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the adjustable prestressed concrete box girder end formwork provided by the present invention.

[0031] Figure 2 This is a schematic diagram of the web of the adjustable prestressed concrete box girder end formwork provided by the present invention.

[0032] Figure 3This is a schematic diagram of the structure of the telescopic plate of the adjustable prestressed concrete box girder end formwork provided by the present invention;

[0033] Figure 4 This is a schematic diagram of the structure connecting the wing plate, top plate, and haunch end sealing template of the adjustable prestressed concrete box girder end template provided by the present invention to the web plate;

[0034] Figure 5 This is a schematic diagram of the prestressed duct adjustment device for the adjustable prestressed concrete box girder end formwork provided by the present invention.

[0035] Figure 6 This is a schematic diagram of the installation structure for the adjustable prestressed concrete box girder end formwork reinforcement construction provided in Embodiment 1 of the present invention;

[0036] Figure 7 yes Figure 6 A magnified view of the circled area in the lower right corner.

[0037] Reference numerals: 1. Telescopic plate; 11. First telescopic plate; 12. Second telescopic plate; 2. Telescopic fixing device; 21. Telescopic fixing rod; 22. Telescopic sleeve; 23. Telescopic fixing screw; 3. Prestressed duct adjustment device; 31. Prestressed duct slot plate; 32. First prestressed duct insert; 33. Second prestressed duct insert; 34. Third prestressed duct insert; 4. Wing plate, top plate and haunch end sealing template; 5. Installation fixing device; 51. Installation fixing screw; 52. Installation fixing sleeve; 61. Inner formwork of cast-in-place box girder; 62. Outer formwork of cast-in-place box girder. Detailed Implementation

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details:

[0040] Example 1

[0041] This embodiment provides an adjustable prestressed concrete box girder end formwork, such as... Figure 1 , Figure 2 and Figure 3As shown, the system includes a wing plate, a top plate and a haunch-end sealing template 4, a web plate, a transverse connecting plate, a telescopic fixing device 2, a prestressed duct adjustment device 3, and an installation fixing device 5. Both the web plate and the transverse connecting plate are composed of telescopic plates 1. The telescopic plate 1 includes a first telescopic plate 11 and a second telescopic plate 12. A rectangular slot is provided at one end of the second telescopic plate 12 along its length. The first telescopic plate 11 is inserted into the rectangular slot of the second telescopic plate 12, and the thickness of the rectangular slot is the same as the thickness of the first telescopic plate 11. The web plate is vertically oriented and includes at least one telescopic plate 1. In this embodiment, as shown... Figure 2 As shown, the web includes two telescopic plates 1 arranged vertically. A prestressed duct adjustment device 3 is provided between these two telescopic plates 1. Since the length of the telescopic plates 1 is adjustable, the height of the prestressed duct adjustment device 3 between the two telescopic plates 1 is also adjustable, which can accommodate the displacement and opening of the prestressed duct at a higher position on the web. The flanges, top plate, and haunch end sealing template 4 are located at the upper end of the web. Since the web is composed of telescopic plates 1 with adjustable length, the height of the flanges, top plate, and haunch end sealing template 4 is adjustable, which can accommodate prestressed concrete box girders of different heights. The transverse connecting plates include an upper transverse connecting plate and a lower transverse connecting plate. The upper transverse connecting plate is used to connect two adjacent flanges, top plates, and haunch end sealing templates 4, and the lower transverse connecting plate is used to connect two adjacent webs. The widths of the upper and lower transverse connecting plates are adjustable.

[0042] like Figure 1 and Figure 2 As shown, the telescopic fixing device 2 includes a telescopic fixing rod 21 and a telescopic sleeve 22. The length directions of both the telescopic fixing rod 21 and the telescopic sleeve 22 are the same as the length direction of the telescopic plate 1 on which the telescopic fixing device 2 is located. The telescopic sleeve 22 is welded to the second telescopic plate 12. One end of the telescopic fixing rod 21 is fixedly connected to the first telescopic plate 11, and the other end passes through the telescopic sleeve 22. The wall of the telescopic sleeve 22 is provided with a threaded through hole leading to the interior of the telescopic sleeve 22. A telescopic fixing screw 23 for fixing the telescopic fixing rod 21 is installed in the threaded through hole. Loosening the telescopic fixing screw 23 allows the first telescopic plate 11 and the telescopic fixing rod 21 to move together. Tightening the telescopic fixing screw 23 fixes the first telescopic plate 11 and the telescopic fixing rod 21, thus fixing the length of the telescopic plate 1. Therefore, the length of the web plate and the transverse connecting plate can be adjusted and fixed by the telescopic fixing device 2.

[0043] like Figure 5As shown, the prestressed duct adjustment device 3 includes a prestressed duct slot plate 31 and prestressed duct inserts. The prestressed duct slot plate 31 is U-shaped, and slot structures are provided on the plate walls on both sides of the opening. The prestressed duct inserts are inserted into the slot structures of the prestressed duct slot plate 31, and the prestressed duct inserts are provided with through holes for the prestressed ducts in the box girder to pass through. The prestressed duct slot plate 31 is provided with threaded through holes leading to its slot structures, and bolts for fixing the prestressed duct inserts are provided in each threaded through hole. The prestressed duct inserts have various structures, and the difference between the prestressed duct inserts with different structures lies in the number and position of the through holes. For example, prestressed duct inserts include prestressed duct inserts with different through hole positions, prestressed duct inserts with different numbers of through holes, and prestressed duct inserts with different through hole positions and numbers. By using prestressed duct inserts with different structures, the position and number of through holes can be adjusted, which can adapt to the displacement of the prestressed duct position to a certain extent.

[0044] like Figure 5 As shown, in this embodiment, the prestressed duct inserts include four different types: a first prestressed duct insert 32, a second prestressed duct insert 33, a third prestressed duct insert 34, and a fourth prestressed duct insert. The first prestressed duct insert 32 has three through holes, which are equidistant along its length. The second prestressed duct insert 33 has two through holes, which correspond one-to-one with any two adjacent through holes in the first prestressed duct insert 32. The third prestressed duct insert 34 has one through hole, which corresponds to any one of the through holes in the first prestressed duct insert 32. The fourth prestressed duct insert has no through holes.

[0045] like Figure 1 , Figure 2 , Figure 4 and Figure 5As shown, in this embodiment, the prestressing duct adjustment device 3 is installed in three locations. The first location is between the two telescopic plates 1 of the web, the second location is at the upper end of the web, and the third location is on the wing plates, top plate, and haunch end sealing template 4 on both sides of the prestressing duct adjustment device 3 at the upper end of the web. Multiple prestressing duct adjustment devices 3 are sequentially arranged along the left-right direction on the wing plates, top plate, and haunch end sealing template 4, and the openings of the prestressing duct slot plates 31 of these sequentially arranged left-right prestressing duct adjustment devices 3 are at the upper end. Multiple prestressing duct adjustment devices 3 are sequentially arranged along the up-down direction at the upper end of the web, and the openings of the prestressing duct slot plates 31 of these sequentially arranged up-down prestressing duct adjustment devices 3 are at the left or right end, and the prestressing duct slot plates 31 of these sequentially arranged up-down prestressing duct adjustment devices 3 protrude outwards, so that the sequentially arranged left-right prestressing duct adjustment devices 3 do not affect the insertion of the prestressing duct inserts. The first prestressed duct adjustment device 3 can adapt to the displacement and opening of the prestressed duct at a high position on the web. The second and third prestressed duct adjustment devices 3 can adapt to the displacement and opening of the prestressed duct at multiple different positions on the flange, top plate and haunch end sealing template 4.

[0046] like Figure 2 , Figure 6 and Figure 7 As shown, the mounting and fixing device 5 includes mounting and fixing screws 51 and mounting and fixing sleeves 52. The mounting and fixing sleeve 52 is fixedly mounted on the second telescopic plate 12 of the telescopic plate 1. The wall of the hole in the mounting and fixing sleeve 52 is provided with a threaded structure that matches the mounting and fixing screws 51. The mounting and fixing screws 51 are threaded into the mounting and fixing sleeve 52. Multiple mounting and fixing devices 5 are provided on the entire end template. Tightening the mounting and fixing screws 51 of each mounting and fixing device 5 can cause each mounting and fixing screw 51 to be tightened against the inner formwork 61 and the outer formwork 62 of the cast-in-place box girder on both sides of the width direction of the telescopic plate 1, thereby fixing the entire end template.

[0047] The working principle of this invention: This invention has three locations for the prestressing duct adjustment device 3. The first location is between the two telescopic plates 1 of the web; the second location is at the upper end of the web; and the third location is on the flanges, top plate, and haunch end sealing template 4 on both sides of the prestressing duct adjustment device 3 at the upper end of the web. The prestressing duct adjustment device 3 at the first location can adapt to the displacement and opening of the prestressing duct at a high position on the web. The multiple prestressing duct adjustment devices 3 at the second and third locations can adapt to the displacement and opening of the prestressing duct at multiple different positions on the flanges, top plate, and haunch end sealing template 4. Therefore, the adjustable prestressed concrete box girder end template provided by this invention has excellent adjustability and can solve the problem of inconsistent template tube hole positions for different prestressing tubes caused by the displacement of the prestressing duct on different box girder template end faces without changing the template.

[0048] Example 2

[0049] This embodiment provides a reinforcement construction method for adjustable prestressed concrete box girder end formwork, using the adjustable prestressed concrete box girder end formwork provided in Embodiment 1, and includes the following steps:

[0050] S100. Assemble the web, transverse connecting plates, wing plates, top plate, and haunch end sealing template 4. Adjust the width according to the box girder cross section. After adjustment, tighten the telescopic fixing screws of each telescopic fixing device 2 to fix the length of the corresponding telescopic plate 1, that is, to fix the length of the web and transverse connecting plates, and to fix the height of the wing plates, top plate, and haunch end sealing template 4.

[0051] S200. Based on the wing plate, top plate and the 4-section end sealing template, make the template panel and install it.

[0052] S300. Based on the location of the prestressed ducts on the box girder, install the prestressed duct adjustment device 3 on the web, flange, top plate, and haunch end sealing template 4. When installing the prestressed duct adjustment device 3, select the relationship between the location of the prestressed duct adjustment device 3 and the location of the prestressed ducts on the box girder, and select a prestressed duct insert of appropriate structure to insert into the prestressed duct slot plate 31.

[0053] S400. Weld an appropriate number of mounting and fixing sleeves 52 onto the second telescopic plate 12 of the telescopic plate 1. The length direction of the mounting and fixing sleeves 52 is along the width direction of the second telescopic plate 12. Install mounting and fixing screws 51 in the mounting and fixing sleeves 52.

[0054] S500. The assembled end formwork is hoisted to the section of the cast-in-place box girder and the installation and fixing screws 51 are tightened so that each installation and fixing screw 51 abuts against and presses against the inner formwork 61 or outer formwork 62 of the cast-in-place box girder set on both sides of the width direction of the expansion plate 1, and the end formwork is fixed on the section of the cast-in-place box girder.

[0055] S600. After the pouring is completed, loosen the installation fixing screws 51, hoist it to the next cast-in-place box girder section, adjust the width and height according to the dimensions of the next cast-in-place box girder section, and fix the length of the corresponding telescopic plate 1 through the telescopic fixing device 2. Finally, tighten the installation fixing screws 51.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adjustable prestressed concrete box girder end formwork, comprising a flange, a top plate, and a haunch-end sealing formwork (4), characterized in that, Also includes: The web is vertically arranged and includes at least one telescopic plate (1). The wing plate, top plate and the axle end sealing template (4) are arranged at the upper end of the web. The transverse connecting plate includes an upper transverse connecting plate and a lower transverse connecting plate. The upper transverse connecting plate is used to connect two adjacent wing plates, a top plate and a haunch end sealing template (4). The lower transverse connecting plate is used to connect two adjacent web plates. Telescopic fixing device (2) is set on telescopic plate (1) and is used to fix the length of telescopic plate (1); The prestressed duct adjustment device (3) is set at the upper end of the web and / or between each telescopic plate (1) of the web and / or on the wing plate, top plate and the haunch end sealing template (4). The prestressed duct adjustment device (3) has a prestressed duct insert, and the prestressed duct insert is provided with a through hole for the prestressed duct in the box girder to pass through. The prestressed duct adjustment device (3) also includes a prestressed duct slot plate (31). The prestressed duct slot plate (31) is in the shape of a U-shaped plate. Slot structures are provided on the plate walls on both sides of the opening of the prestressed duct slot plate (31). The prestressed duct insert is inserted into the slot structure of the prestressed duct slot plate (31). Multiple prestressed duct adjustment devices (3) are arranged sequentially along the left-right direction on the wing plate, top plate and the axle end sealing template (4), and the opening of the prestressed duct slot plate (31) of these left-right arranged prestressed duct adjustment devices (3) is at the upper end; multiple prestressed duct adjustment devices (3) are arranged sequentially along the up-down direction on the upper end of the web plate, and the opening of the prestressed duct slot plate (31) of these up-down arranged prestressed duct adjustment devices (3) is at the left or right end, and the prestressed duct slot plate (31) of these up-down arranged prestressed duct adjustment devices (3) protrudes outward, so that the left-right arranged prestressed duct adjustment devices (3) do not affect the insertion of the prestressed duct insert.

2. The adjustable prestressed concrete box girder end formwork according to claim 1, characterized in that, It also includes a mounting and fixing device (5) set on the telescopic plate (1). The mounting and fixing device (5) has a screw-on mounting and fixing screw (51). Tightening the mounting and fixing screw (51) can tighten the inner formwork (61) or outer formwork (62) of the cast-in-place box girder set on both sides of the width direction of the telescopic plate (1).

3. The adjustable prestressed concrete box girder end formwork according to claim 1, characterized in that, The telescopic plate (1) includes a first telescopic plate (11) and a second telescopic plate (12). A rectangular slot is provided at one end of the second telescopic plate (12) along its length. The rectangular slot is arranged along the length of the second telescopic plate (12). The first telescopic plate (11) is inserted into the rectangular slot of the second telescopic plate (12). The thickness of the rectangular slot is the same as the thickness of the first telescopic plate (11).

4. An adjustable prestressed concrete box girder end formwork according to claim 3, characterized in that, The telescopic fixing device (2) includes a telescopic fixing rod (21) and a telescopic sleeve (22). The length directions of the telescopic fixing rod (21) and the telescopic sleeve (22) of the telescopic fixing device (2) are the same as the length direction of the telescopic plate (1) where the telescopic fixing device (2) is located. The telescopic sleeve (22) is fixedly installed on the second telescopic plate (12). One end of the telescopic fixing rod (21) is fixedly installed on the first telescopic plate (11), and the other end passes through the telescopic sleeve (22). The wall of the telescopic sleeve (22) is provided with a threaded through hole leading to the interior of the telescopic sleeve (22). A telescopic fixing screw (23) for fixing the telescopic fixing rod (21) is installed in the threaded through hole.

5. An adjustable prestressed concrete box girder end formwork according to claim 2, characterized in that, The mounting and fixing device (5) further includes a mounting and fixing sleeve (52), which is fixedly mounted on the telescopic plate (1). The wall of the hole of the mounting and fixing sleeve (52) is provided with a thread structure that matches the mounting and fixing screw (51), and the mounting and fixing screw (51) is threaded into the mounting and fixing sleeve (52).

6. An adjustable prestressed concrete box girder end formwork according to claim 1, characterized in that, The prestressed duct insert includes a variety of prestressed duct inserts with different through hole positions, the prestressed duct insert includes a variety of prestressed duct inserts with different numbers of through holes, and the prestressed duct insert includes a variety of prestressed duct inserts with different through hole positions and numbers; the prestressed duct slot plate (31) is provided with threaded through holes leading to its slot structure, and each threaded through hole is provided with bolts for fixing the prestressed duct insert.

7. An adjustable prestressed concrete box girder end formwork according to claim 6, characterized in that, The prestressed duct inserts include a first prestressed duct insert (32), a second prestressed duct insert (33), and a third prestressed duct insert (34). The first prestressed duct insert (32) has three through holes, which are equidistant along the length of the first prestressed duct insert (32). The second prestressed duct insert (33) has two through holes, which correspond one-to-one with the positions of any two adjacent through holes in the three through holes of the first prestressed duct insert (32). The third prestressed duct insert (34) has one through hole, which corresponds to the position of any one of the through holes in the second prestressed duct insert (33).

8. A reinforcement construction method for adjustable prestressed concrete box girder end formwork, using the adjustable prestressed concrete box girder end formwork as described in any one of claims 1-7, characterized in that, Includes the following steps: S100, Assemble the web plate, transverse connecting plate, wing plate, top plate and haunch end sealing template (4), adjust the width according to the box girder section, and fix the length of the corresponding telescopic plate (1) through the telescopic fixing device (2); S200. Based on the wing plate, top plate and the end cap template (4), make the template panel and install it; S300. Install prestressed duct adjustment devices (3) on the web, flange, top plate and haunch end sealing template (4) according to the location of the prestressed ducts on the box girder; S400. Install a fixing device (5) on the telescopic plate (1), the fixing device (5) having a screw-on fixing screw (51); S500, hoist the whole to the section of the cast-in-place box girder, tighten the installation fixing screws (51), press against the inner formwork (61) or outer formwork (62) of the cast-in-place box girder set on both sides of the width direction of the telescopic plate (1), and fix the end formwork on the section of the cast-in-place box girder. S600. After the pouring is completed, loosen the installation fixing screws (51), hoist it to the next cast-in-place box girder section, adjust the width and height according to the dimensions of the next cast-in-place box girder section, and fix the length of the corresponding telescopic plate (1) through the telescopic fixing device (2), and finally tighten the installation fixing screws (51).

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