Variable fulcrum construction auxiliary beam for underneath passing existing line construction and construction method

Abstract

The invention provides a variable fulcrum construction auxiliary beam for underneath pass existing line construction and a construction method. The variable fulcrum construction auxiliary beam comprises a plurality of longitudinal beams, and each longitudinal beam comprises a first top plate, a first bottom plate, two first webs, a plurality of first reinforcing ribs and a plurality of splice plates. According to the variable fulcrum construction auxiliary beam for underneath pass existing line construction and the construction method, through mutual cooperation of the longitudinal beams, the cross beams and the transverse lifting beams, when the auxiliary beam is used, the transverse lifting beams penetrate into the bottoms of steel rails, are fixed to the tops of pile columns to support the longitudinal beams, penetrate into the cross beams and are connected with the line steel rails; according to the construction auxiliary beam, the longitudinal beams are hoisted for connection, the multiple longitudinal beams are spliced and the like, the positions of fulcrums can be changed according to on-site arrangement, so that the construction auxiliary beam can be flexibly adjusted according to different geological conditions and construction requirements, the performance of the construction auxiliary beam is greatly improved, and the construction auxiliary beam is not limited by a fixed structure any more; the device can better adapt to various complex construction sites, and the application range of the device is widened.

Description

Technical Field

[0001] The invention relates to the field of bridge steel structure processing and manufacturing, and in particular to a variable fulcrum construction temporary beam for underpass existing lines and a construction method. Background Art

[0002] In recent years, with the development of my country's local economy, municipal engineering projects such as converting level crossings into overpasses and new railways passing under existing lines have been implemented. There are more and more bridge and culvert reinforcement, bridge replacement, tunnel excavation, and box culvert jacking projects, and various types of aperture frame structures are being used in more and more cities.

[0003] During construction, in order to avoid affecting the normal operation of the existing railway, it is necessary to temporarily build temporary beams when passing under the railway to support the railway. In the traditional construction of railways passing under existing lines, although the D-type construction temporary beams have certain structural characteristics and connection methods, some problems have gradually been exposed in actual applications. The box-shaped section of the main longitudinal beam and the H-shaped section design of the cross beam, as well as the connection through splicing plates and corbels and the use of refined bolt connection joints, to a certain extent, ensure the stability of the structure. At the same time, the line track and the cross beam are connected by adjustable rail fasteners, which can realize the longitudinal and lateral adjustment of the rail spacing. The horizontal connection system set under the cross beam also helps to enhance the stability of the overall structure.

[0004] However, with the continuous development of engineering construction, the geological conditions and construction requirements of the construction site are becoming increasingly complex and changeable. Due to the relatively fixed structure of this type of temporary beam, it is difficult to flexibly adjust according to different actual conditions. When faced with complex geological conditions, it may not provide sufficient adaptability, resulting in unstable factors during the construction process. Moreover, when encountering large-span construction needs, its existing structure often cannot meet the engineering requirements, limiting the flexibility and scope of application of the construction, which not only increases the difficulty and risk of construction, but also affects the progress and quality of the project.

[0005] Therefore, it is necessary to provide a variable support point construction temporary beam and a construction method for construction under an existing line to solve the above technical problems. Summary of the invention

[0006] The present invention provides a temporary beam with a variable fulcrum for construction under an existing line and a construction method, which solves the problems that the temporary beam structure is fixed, is difficult to adapt to complex geological conditions and large-span construction requirements, limits flexibility and scope of application, increases construction difficulty and risk, and affects project progress and quality.

[0007] In order to solve the above technical problems, the present invention provides a variable support point construction beam for underpass existing line construction, comprising:

[0008] A plurality of longitudinal beams, each of the plurality of longitudinal beams comprises a first top plate, a first bottom plate, two first web plates, a plurality of first reinforcing ribs and a plurality of splicing plates, the top and bottom of the two first web plates are respectively fixedly mounted on the bottom of the first top plate and the top of the first bottom plate, the plurality of splicing plates are respectively arranged on the top and bottom of the first top plate and the first bottom plate, and on both sides of the two first web plates, and the bottom of the first bottom plate is evenly provided with a plurality of first connecting holes;

[0009] A plurality of cross beams, each of which is arranged at the bottom of the longitudinal beam, each of which comprises a second top plate, a second bottom plate, a second web plate, a plurality of reinforcing plates and two side baffles, the top and bottom of the second web plate are respectively fixedly mounted on the bottom of the second top plate and the top of the second bottom plate, and a plurality of second connecting holes are opened on the top of the second top plate;

[0010] Multiple cross-lifting beams are arranged at the bottom of the longitudinal beams, and multiple cross-lifting beams include a third top plate, a third bottom plate, two third web plates and multiple partitions, and the tops and bottoms of the multiple partitions are respectively fixedly connected to the bottom of the third top plate and the top of the third bottom plate, and multiple third connecting holes are opened on the top of the third top plate.

[0011] Preferably, the tops and bottoms of the plurality of first reinforcing ribs are respectively fixedly connected to the bottom of the first top plate and the top of the first bottom plate, and the plurality of first reinforcing ribs are respectively fixedly connected to the side surfaces of the two first webs.

[0012] Preferably, the plurality of reinforcing plates are respectively fixedly connected to two sides of the second web, and the tops of the plurality of reinforcing plates are fixedly connected to the bottom of the second top plate.

[0013] Preferably, the two side baffles are respectively arranged on both sides of the second web, the side surfaces of the two side baffles are fixedly connected to the side surfaces of the plurality of reinforcement plates, and the tops of the two side baffles are fixedly connected to the bottom of the second top plate.

[0014] Preferably, the two third webs are respectively fixedly connected to two sides of the plurality of partitions, and the tops and bottoms of the two third webs are respectively fixedly connected to the bottom of the third top plate and the top of the third bottom plate.

[0015] Preferably, the bottom of the first bottom plate is respectively arranged on the top of the second top plate and the third top plate.

[0016] Preferably, supporting plates are provided at both ends of the bottom of the third bottom plate, threaded rods are provided inside the four sides of the supporting plates, and support plates are fixedly installed at the bottoms of the four threaded rods.

[0017] Preferably, a plurality of sleepers are provided at the bottom of the support plate, and a first nut and a second nut are provided at the bottom and the bottom of the support plate respectively, and the first nut and the second nut are both threadedly connected to the outer side surface of the threaded rod.

[0018] Preferably, connecting bolts are arranged inside all four sides of the support plate.

[0019] In order to solve the above problems, the present invention also provides a construction method of a variable fulcrum construction temporary beam for construction under an existing line, comprising the following steps:

[0020] S1. During construction, the horizontal beams are inserted into the bottom of the rails, so that the horizontal beams are spaced and avoid the longitudinal beam joints, and the two ends of the horizontal beams are fixed on the top of the piles, so that they can support the longitudinal beams when they are installed later;

[0021] S2. Then, remove the ballast between the sleepers, insert each ballast into the steel beam, and use adjustable rail fasteners to firmly connect the line rails to the beams;

[0022] S3. Then use a 50t truck crane and a flatbed trailer to transport the longitudinal beam to the site, check whether the beam bottom corresponds to the bolt hole in the middle support, correct the size deviation, and check the plane size and elevation of the embedded parts and support parts on the bored piles;

[0023] S4. The longitudinal beam adopts splicing. When installing, each segment is hoisted in place separately, and then spliced ​​into a whole. High-strength bolts are used to connect the segments. When the longitudinal beam segments are assembled into a whole, the straightness of the longitudinal beam should be adjusted first, and the lateral bend should not be greater than 5mm (based on the web plane), and then the high-strength bolts can be installed;

[0024] S5. Then connect the top of the cross beam and the cross lifting beam to the longitudinal beam through bolts, and open the line after the construction scope meets the conditions for train release.

[0025] Compared with the related art, the variable fulcrum construction temporary beam and construction method provided by the present invention for construction under the existing line have the following beneficial effects:

[0026] The present invention provides a construction beam with a variable fulcrum for underpass existing lines and a construction method. The longitudinal beam, the transverse beam and the transverse lifting beam cooperate with each other. When in use, the transverse lifting beam is inserted into the bottom of the rail and fixed on the top of the pile to provide support for the longitudinal beam, the transverse beam is inserted into the cross beam and connected to the line rail, the longitudinal beam is hoisted for connection, and a plurality of longitudinal beams are spliced, etc. The fulcrum position can be changed according to the on-site layout, so that the construction beam can be flexibly adjusted according to different geological conditions and construction requirements, which greatly improves the performance of the construction beam, is no longer limited by a fixed structure, can better adapt to various complex construction sites, expands its scope of application, and meets the needs of different spans on site; and can effectively improve the bearing capacity and adaptability of the structure, and can provide more reliable support when facing the engineering needs of large-span box culvert jacking, thereby improving the progress and quality of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of a first embodiment of a variable fulcrum construction beam for underpass construction of an existing line provided by the present invention;

[0028] Figure 2 for Figure 1 The end face structure schematic diagram shown;

[0029] Figure 3 for Figure 1 The schematic diagram of the longitudinal beam side structure shown;

[0030] Figure 4 for Figure 3 The schematic diagram of the bottom structure of the longitudinal beam is shown;

[0031] Figure 5 for Figure 3 The schematic diagram of the longitudinal beam cross-section structure shown;

[0032] Figure 6 for Figure 1 The schematic diagram of the side structure of the beam shown;

[0033] Figure 7 for Figure 6 A schematic diagram of the top structure of the beam shown;

[0034] Figure 8 for Figure 6 The cross-beam cross-section structure diagram shown in FIG.

[0035] Fig. 9 for Figure 1 The schematic diagram of the side structure of the horizontal lifting beam shown;

[0036] Fig.10 for Fig. 9 The schematic diagram of the bottom structure of the horizontal lifting beam shown;

[0037] Fig.11 for Fig. 9 The cross-sectional structure diagram of the horizontal lifting beam shown in FIG.

[0038] Fig.12 A schematic structural diagram of a second embodiment of a variable fulcrum construction beam for underpass construction of an existing line provided by the present invention;

[0039] Fig.13 for Fig.12 The side structure diagram of the support plate is shown.

[0040] Numbers in the figure: 1. longitudinal beam, 11. first top plate, 12. first bottom plate, 121. first connecting hole, 13. first web, 14. first reinforcing rib, 15. splicing plate, 2. cross beam, 21. second top plate, 211. second connecting hole, 22. second bottom plate, 23. second web, 24. reinforcing plate, 25. side baffle, 3. cross beam, 31. third top plate, 32. third bottom plate, 321. third connecting hole, 33. third web, 34. partition, 4. support plate, 41. connecting bolt, 42. threaded rod, 43. first nut, 44. second nut, 45. sleeper, 46. support plate. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0042] First embodiment

[0043] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 and Fig.11 ,in, Figure 1 A schematic structural diagram of a first embodiment of a variable fulcrum construction beam for underpass construction of an existing line provided by the present invention; Figure 2 for Figure 1 The end face structure schematic diagram shown; Figure 3 for Figure 1 The schematic diagram of the longitudinal beam side structure shown; Figure 4 for Figure 3 The schematic diagram of the bottom structure of the longitudinal beam is shown;

[0044] Figure 5 for Figure 3 The schematic diagram of the longitudinal beam cross-section structure shown; Figure 6 for Figure 1 The schematic diagram of the side structure of the beam shown; Figure 7 for Figure 6 A schematic diagram of the top structure of the beam shown; Figure 8 for Figure 6 The cross-beam cross-section structure diagram shown in FIG. Fig. 9 for Figure 1 The schematic diagram of the side structure of the horizontal lifting beam shown; Fig.10 for Fig. 9 The schematic diagram of the bottom structure of the horizontal lifting beam shown; Fig.11 for Fig. 9 The cross-sectional structure diagram of the horizontal beam is shown. A variable fulcrum construction beam and construction method for underpass existing lines, comprising: a plurality of longitudinal beams 1, each of the plurality of longitudinal beams 1 comprises a first top plate 11, a first bottom plate 12, two first webs 13, a plurality of first reinforcing ribs 14 and a plurality of splicing plates 15, the top and bottom of the two first webs 13 are respectively fixedly mounted on the bottom of the first top plate 11 and the top of the first bottom plate 12, the plurality of splicing plates 15 are respectively arranged on the top and bottom of the first top plate 11 and the first bottom plate 12, and on both sides of the two first webs 13, the bottom of the first bottom plate 12 is evenly provided with a plurality of first connection holes 121;

[0045] A plurality of cross beams 2, each of which is arranged at the bottom of the longitudinal beam 1, and each of which comprises a second top plate 21, a second bottom plate 22, a second web plate 23, a plurality of reinforcing plates 24 and two side baffles 25, the top and bottom of the second web plate 23 are respectively fixedly mounted on the bottom of the second top plate 21 and the top of the second bottom plate 22, and a plurality of second connecting holes 211 are opened on the top of the second top plate 21;

[0046] Multiple cross-lifting beams 3 are arranged at the bottom of the longitudinal beam 1, and multiple cross-lifting beams 3 include a third top plate 31, a third bottom plate 32, two third webs 33 and multiple partitions 34, the tops and bottoms of the multiple partitions 34 are respectively fixedly connected to the bottom of the third top plate 31 and the top of the third bottom plate 32, and the top of the third top plate 31 is provided with multiple third connecting holes 321.

[0047] The tops and bottoms of the plurality of first reinforcing ribs 14 are respectively fixedly connected to the bottom of the first top plate 11 and the top of the first bottom plate 12 , and the plurality of first reinforcing ribs 14 are respectively fixedly connected to the side surfaces of the two first webs 13 .

[0048] The plurality of reinforcing plates 24 are respectively fixedly connected to two sides of the second web 23 , and the tops of the plurality of reinforcing plates 24 are all fixedly connected to the bottom of the second top plate 21 .

[0049] The two side baffles 25 are respectively arranged on both sides of the second web 23 , the sides of the two side baffles 25 are fixedly connected to the sides of the plurality of reinforcing plates 24 , and the tops of the two side baffles 25 are fixedly connected to the bottom of the second top plate 21 .

[0050] The two third webs 33 are respectively fixedly connected to two sides of the plurality of partitions 34 , and the tops and bottoms of the two third webs 33 are respectively fixedly connected to the bottom of the third top plate 31 and the top of the third bottom plate 32 .

[0051] The bottom of the first bottom plate 12 is disposed on the top of the second top plate 21 and the third top plate 31 .

[0052] Multiple longitudinal beams 1 are spliced ​​into a whole when installed on the construction site. The splicing adopts bolted joints. Bolt hole groups are set at the top plate, the bottom plate and the ends of the web plate for splicing when the porous beams are used continuously. Splicing plates 15 are set on the outside of the top plate and the bottom plate, and splicing plates 15 are set on both sides of the web plate. The splicing bolts adopt M24 high-strength bolts, and the friction surface is treated with aluminum spraying.

[0053] The cross beam 2 is connected to the bottom of the longitudinal beam 1 by bolts. The cross beam 1 adopts an I-shaped section. The second top plate 21 is 200 mm wide and 20 mm thick. The second web plate 23 is 172 mm high and 20 mm thick. The second bottom plate 22 is 220 mm wide and 20 mm thick.

[0054] When constructing in a long rail section, in order to increase the lateral stability of the long rail, a side baffle 25 is installed on the crossbeam 2 and the ballast bed is tamped;

[0055] The transverse beam 3 adopts a box-shaped structure, which is connected to the bottom plate of the longitudinal beam 1 by bolts in the middle, and anchored on the temporary pier by bolts passing through the third connection holes 321 at both ends. The thickness of the third top plate 31 and the third bottom plate 32 are both 40mm, the thickness of the third web plate 33 is 24mm, the overall height is 700mm, and the width is 370mm;

[0056] By changing the simply supported beam of the D-type construction beam into a continuous beam, the bearing capacity and adaptability of the structure can be effectively improved to meet the engineering requirements of large-span box culvert jacking. This transformation requires comprehensive consideration of design, construction, materials, safety and economy to ensure the successful implementation of the project.

[0057] The segmented longitudinal beam 1 is supplied to reduce the unit size and weight, and solve the difficulties in manufacturing, transporting and storing the construction beam. The box-type section is adopted, so it has good rigidity and stability. The interface is connected with a splicing plate 15, which effectively strengthens the longitudinal connection of the beam, improves the vibration characteristics, and improves the driving safety. It can further adapt to the needs of railway construction to meet the requirements of on-site use. It has the advantages of fast passing speed, good lateral stability, and small deflection of the main longitudinal beam 1.

[0058] The working principle of a variable fulcrum construction temporary beam and a construction method provided by the present invention for construction under an existing line is as follows:

[0059] During construction, the horizontal lifting beam 3 is inserted into the bottom of the rail, so that the horizontal lifting beam 3 is spaced and avoids the joint of the longitudinal beam 1, and the two ends of the horizontal lifting beam 3 are fixed to the top of the pile column, so as to support the longitudinal beam 1 when it is installed later; then the ballast between the sleepers is removed, and the steel cross beams 2 are inserted one by one, and the line rails and the cross beams 2 are firmly connected using adjustable rail fasteners; then the longitudinal beam 1 is hoisted to the top of the horizontal lifting beam 3, and then the installation bolts are respectively passed through the first connection hole 121 and the third connection hole 321 to connect the longitudinal beam 1 and the horizontal lifting beam 3, and then the installation bolts are respectively passed through the other first connection holes 121 and the second connection holes 211 to connect the cross beam 2 and the longitudinal beam 1;

[0060] When multiple longitudinal beams 1 need to be spliced, the end faces of two longitudinal beams 1 are butt-jointed, and then multiple splicing plates 15 are used to respectively connect the first top plate 11, the first bottom plate 12 and the first web plate 13 on the two longitudinal beams 1 by installing bolts, thereby connecting the multiple longitudinal beams 1.

[0061] Compared with the related art, the variable fulcrum construction temporary beam and construction method provided by the present invention for construction under the existing line have the following beneficial effects:

[0062] Through the cooperation between the longitudinal beam 1, the transverse beam 2 and the cross-lifting beam 3, when in use, the cross-lifting beam 3 is inserted into the bottom of the rail and fixed on the top of the pile to provide support for the longitudinal beam 1, inserted into the cross beam 2 and connected to the line rail, the longitudinal beam 1 is hoisted for connection and multiple longitudinal beams 1 are spliced, etc. The fulcrum position can be changed according to the on-site layout, which makes the construction beam flexibly adjustable according to different geological conditions and construction requirements, greatly improving the performance of the construction beam, no longer limited to a fixed structure, can better adapt to various complex construction sites, expand its scope of application, and meet the needs of different spans on site; and can effectively improve the bearing capacity and adaptability of the structure, when facing the engineering needs of large-span box culvert jacking, it can provide more reliable support and improve the progress and quality of the project.

[0063] Second embodiment

[0064] Please refer to Fig.11 and Fig.13Based on the variable support point construction beam and construction method for underpass existing lines provided in the first embodiment of the present application, the second embodiment of the present application proposes another variable support point construction beam and construction method for underpass existing lines. The second embodiment is only a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0065] Specifically, the second embodiment of the present application provides a variable fulcrum construction beam and a construction method for construction under an existing line. The difference is that, in the variable fulcrum construction beam and a construction method for construction under an existing line, both ends of the bottom of the third base plate 32 are provided with support plates 46, and threaded rods 42 are provided inside around the support plate 46, and support plates 4 are fixedly installed at the bottom of the four threaded rods 42.

[0066] A plurality of sleepers 45 are disposed at the bottom of the support plate 46 , and a first nut 43 and a second nut 44 are disposed at the bottom and the bottom of the support plate 46 , respectively. The first nut 43 and the second nut 44 are both threadedly connected to the outer side surface of the threaded rod 42 .

[0067] Connecting bolts 41 are arranged inside the four sides of the support plate 4 .

[0068] The working principle of a variable fulcrum construction temporary beam and a construction method provided by the present invention for construction under an existing line is as follows:

[0069] When in use, if the two ends of the cross-lifting beam 3 are not at the same level due to errors in pouring the piles, the user can place the support plate 46 at the bottom of the third base plate 32, and pass the threaded rod 42 into the third connecting hole 321, and then place the support plate 4 on the top of the pile, and connect the support plate 4 and the pile through the connecting bolts 41, and then the user rotates multiple first nuts 43 set at the bottom of the support plate 46 to adjust the height of the support plate 46, thereby adjusting the height of the two ends of the cross-lifting beam 3. After adjusting the appropriate height, the second nut 44 is threadedly connected to the outer side of the threaded rod 42 and is located at the top of the third base plate 32, thereby limiting the cross-lifting beam 3, and then multiple sleepers 45 are placed between the support plate 4 and the support plate 46, thereby supporting the support plate 46.

[0070] Compared with the related art, the variable fulcrum construction temporary beam and construction method provided by the present invention for construction under the existing line have the following beneficial effects:

[0071] The structures such as the support plate 4, the connecting bolts 41, the threaded rod 42, the first nut 43, the second nut 44, the sleepers 45 and the support plate 46 cooperate with each other. When in use, the connecting bolts 41 pass through the inside of the support plate 4 and connect with the piles, and the top of the support plate 46 abuts against the bottom of the cross-lifting beam 3, and the height of the support plate 46 is adjusted by the first nut 43, so that the height of the two ends of the cross-lifting beam 3 can be adjusted to ensure the stability of the installation.

[0072] In order to solve the above problems, the present invention also provides a construction method of a variable fulcrum construction temporary beam for construction under an existing line, comprising the following steps:

[0073] S1. During construction, the horizontal beam 3 is inserted into the bottom of the rail so that the horizontal beams 3 are spaced and avoid the joints of the longitudinal beam 1, and the two ends of the horizontal beam 3 are fixed to the top of the pile column so that the longitudinal beam 1 can be supported when it is installed later;

[0074] S2, then remove the ballast between the sleepers, insert them into the steel beam 2 one by one, and use the adjustable rail fastener to firmly connect the line rail and the beam 2;

[0075] S3. Then use a 50t truck crane and a flatbed trailer to transport the longitudinal beam 1 to the site, check whether the beam bottom corresponds to the bolt hole in the middle support, correct the size deviation, and check the plane size and elevation of the embedded parts and support parts on the bored pile;

[0076] S4. The longitudinal beam 1 is spliced. When installing, each segment is hoisted in place separately, and then spliced ​​into a whole. The segments are connected with high-strength bolts. When the beam segments of the longitudinal beam 1 are assembled into a whole, the straightness of the longitudinal beam 1 should be adjusted first, and the lateral bend should not be greater than 5mm (based on the web plane), and then the high-strength bolts can be installed;

[0077] S5. Then connect the top of the cross beam 2 and the cross beam 1 to the longitudinal beam 1 through bolts, and open the line after the construction scope meets the conditions for train release.

[0078] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A variable support point construction beam for construction under an existing line. It is characterized in that include: A plurality of longitudinal beams, each of the plurality of longitudinal beams comprises a first top plate, a first bottom plate, two first web plates, a plurality of first reinforcing ribs and a plurality of splicing plates, the top and bottom of the two first web plates are respectively fixedly mounted on the bottom of the first top plate and the top of the first bottom plate, the plurality of splicing plates are respectively arranged on the top and bottom of the first top plate and the first bottom plate, and on both sides of the two first web plates, and the bottom of the first bottom plate is evenly provided with a plurality of first connecting holes; A plurality of cross beams, each of which is arranged at the bottom of the longitudinal beam, each of which comprises a second top plate, a second bottom plate, a second web plate, a plurality of reinforcing plates and two side baffles, the top and bottom of the second web plate are respectively fixedly mounted on the bottom of the second top plate and the top of the second bottom plate, and a plurality of second connecting holes are opened on the top of the second top plate; Multiple cross-lifting beams are arranged at the bottom of the longitudinal beams, and multiple cross-lifting beams include a third top plate, a third bottom plate, two third web plates and multiple partitions, and the tops and bottoms of the multiple partitions are respectively fixedly connected to the bottom of the third top plate and the top of the third bottom plate, and multiple third connecting holes are opened on the top of the third top plate.

2. A variable fulcrum construction beam for construction under an existing line according to claim 1, It is characterized in that The tops and bottoms of the plurality of first reinforcing ribs are respectively fixedly connected to the bottom of the first top plate and the top of the first bottom plate, and the plurality of first reinforcing ribs are respectively fixedly connected to the side surfaces of the two first webs.

3. A variable fulcrum construction beam for construction under an existing line according to claim 1, It is characterized in that The plurality of reinforcing plates are respectively fixedly connected to two sides of the second web, and the tops of the plurality of reinforcing plates are fixedly connected to the bottom of the second top plate.

4. A variable fulcrum construction beam for construction under an existing line according to claim 3, It is characterized in that The two side baffles are respectively arranged on both sides of the second web, the side surfaces of the two side baffles are fixedly connected to the side surfaces of the plurality of reinforcement plates, and the tops of the two side baffles are fixedly connected to the bottom of the second top plate.

5. The variable fulcrum construction beam for underpass construction of an existing line according to claim 1, It is characterized in that The two third webs are respectively fixedly connected to the two sides of the plurality of partitions, and the tops and bottoms of the two third webs are respectively fixedly connected to the bottom of the third top plate and the top of the third bottom plate.

6. A variable fulcrum construction beam for construction under an existing line according to claim 1, It is characterized in that The bottom of the first bottom plate is respectively arranged on the top of the second top plate and the third top plate.

7. The variable support point construction beam for underpass construction of an existing line according to claim 1, It is characterized in that Support plates are provided at both ends of the bottom of the third bottom plate, threaded rods are provided inside the four sides of the support plates, and support plates are fixedly installed at the bottoms of the four threaded rods.

8. A variable fulcrum construction beam for construction under an existing line according to claim 7, It is characterized in that A plurality of sleepers are arranged at the bottom of the support plate, and a first nut and a second nut are arranged at the bottom and the bottom of the support plate respectively, and the first nut and the second nut are both threadedly connected to the outer side surface of the threaded rod.

9. A variable fulcrum construction beam for construction under an existing line according to claim 8, It is characterized in that Connecting bolts are arranged inside the four sides of the support plate.

10. A construction method for a variable fulcrum construction beam for construction under an existing line, It is characterized in that The following steps are involved: S1. During construction, the horizontal beams are inserted into the bottom of the rails, so that the horizontal beams are spaced and avoid the longitudinal beam joints, and the two ends of the horizontal beams are fixed on the top of the piles, so that they can support the longitudinal beams when they are installed later; S2. Then, remove the ballast between the sleepers, insert each ballast into the steel beam, and use adjustable rail fasteners to firmly connect the line rails to the beams; S3. Then use a 50t truck crane and a flatbed trailer to transport the longitudinal beam to the site, check whether the beam bottom corresponds to the bolt hole in the middle support, correct the size deviation, and check the plane size and elevation of the embedded parts and support parts on the bored piles; S4. The longitudinal beam adopts splicing. When installing, each segment is hoisted in place separately, and then spliced ​​into a whole. High-strength bolts are used to connect the segments. When the longitudinal beam segments are assembled into a whole, the straightness of the longitudinal beam should be adjusted first, and the lateral bend should not be greater than 5mm (based on the web plane), and then the high-strength bolts can be installed; S5. Then connect the top of the cross beam and the cross lifting beam to the longitudinal beam through bolts, and open the line after the construction scope meets the conditions for train release.

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