A method for dismantling an old frame bridge under a railway operating line

Abstract

The present invention relates to the technical field of bridge engineering construction, and discloses a method for dismantling an old frame bridge under a railway operating line, comprising S1, supporting a formwork in the middle of the old frame bridge, pouring concrete to form a plain concrete strip foundation, hanging a steel mesh on the outside of the plain concrete strip foundation and anchoring it into the top plate and bottom plate of the old frame bridge. S2, constructing independent piers at corresponding positions according to the specifications of D-type temporary beams, so that the D-type temporary beams are erected between the top plate and the independent piers of the frame bridge directly above the plain concrete strip foundation, and reinforcing the corresponding railway tracks. The method for dismantling an old frame bridge under a railway operating line of the present invention abandons the traditional construction method of simple rope saw cutting or simple overall ejection in the dismantling of old frame bridges, and solves the problem that the width of the old frame bridge is so large that the widest type of D-type temporary beam cannot be installed on its upper part. The advantages of multiple construction methods complement each other, reasonably solve the construction problems, and have strong operability.

Description

Technical Field

[0001] The invention relates to the technical field of bridge engineering construction, and in particular to a method for dismantling an old frame bridge under a railway operating line. Background Art

[0002] With the increase of urban population and traffic demand, the capacity of the original operating railway frame bridge can no longer meet the use requirements, forming a traffic jam in the city and restricting the needs of economic development. Removing the existing old frame bridge, building a new larger frame bridge, and widening and renovating the old road have become urgent needs for urban development.

[0003] Before dismantling the old frame bridge, it is necessary to use D-type temporary beams to reinforce the railway tracks within a certain range above the frame bridge. D-type temporary beams generally have several models, D12, D16, D20, and D24, with a maximum span of 24m. If the width of the old frame bridge of the project is large, even if a D-type temporary beam with a maximum span of 24m is used, the net width on both sides of the frame bridge is not enough to set up the pile foundation and strip foundation supporting the D-type temporary beam. At this time, it is difficult to use the common methods of dismantling the old frame bridge (overall ejection method, rope saw cutting method).

[0004] Therefore, a method for dismantling old frame bridges under railway operating lines was proposed in combination with the actual site conditions, construction period and cost requirements. Summary of the invention

[0005] In order to make up for the defects of the prior art, the purpose of the present invention is to provide a method for dismantling an old frame bridge under a railway operating line, which adopts the method of partial cutting and ejecting the remaining part, and can quickly and safely realize the dismantling construction of the old frame bridge, thereby achieving the purpose of shortening the construction period and saving construction costs.

[0006] The present invention is implemented by the following technical solution: A method for dismantling an old frame bridge under a railway operating line comprises the following steps:

[0007] S1. Formwork is supported in the middle of the old frame bridge, and concrete is poured to form a plain concrete strip foundation. A steel mesh is hung on the outside of the plain concrete strip foundation and anchored into the top and bottom plates of the old frame bridge;

[0008] S2. construct independent piers at corresponding positions according to the specifications of the D-type temporary beam, so that the D-type temporary beam is erected between the top plate of the frame bridge and the independent piers directly above the plain concrete strip foundation, and reinforce the corresponding railway tracks;

[0009] S3, excavate and slope the soil outside the outer wall of the old frame bridge to form an excavation and slope surface;

[0010] S4, use temporary supports to reinforce the top plate inside the old frame bridge;

[0011] S5, sequentially remove the connection parts between the top plate and the side wall of the old frame bridge, the side walls on both sides of the old frame bridge, and the connection parts between the bottom plate and the side wall of the old frame bridge;

[0012] S6. Dig holes below the bottom plate of the old frame bridge to form multiple pile holes evenly distributed;

[0013] S7, sequentially placing steel cages in each pile hole, supporting formwork above the ground, and pouring concrete to form a pile foundation;

[0014] S8. Formwork is supported on the top of the pile foundation on the same side, steel bars are tied, and concrete is poured to form a reinforced concrete strip foundation;

[0015] S9. Use the temporary beam conversion method to set up D-type temporary beams between two reinforced concrete strip foundations and between reinforced concrete strip foundations and independent piers to reinforce the corresponding railway tracks;

[0016] S10. Based on the completed new frame bridge, the remaining part of the old frame bridge and the internal plain concrete strip foundation are pushed out and removed as a whole.

[0017] As a further improvement of the above solution, in step S1, cutting holes for later cutting are uniformly embedded in the concrete strip foundation.

[0018] As a further improvement of the above solution, in step S3, steel mesh and shotcrete are hung on the slope for protection.

[0019] As a further improvement of the above solution, in step S3, holes are drilled and ropes are passed through, and a rope saw is used to cut and remove the connection between the top plate and the side wall of the old frame bridge and the connection between the bottom plate and the side wall of the old frame bridge.

[0020] As a further improvement of the above solution, in step S3, a circular saw is used to cut and remove the side walls on both sides of the old frame bridge.

[0021] As a further improvement of the above solution, in step S6, a manual hole digging construction method is adopted to form a plurality of pile holes that are evenly distributed.

[0022] As a further improvement of the above solution, in step S10, the old frame bridge is dismantled by a construction method of partial cutting and overall ejecting of the remaining parts.

[0023] As a further improvement of the above solution, the method further includes step S11, wherein the temporary support is removed after the old frame bridge is pushed out of the safety range of the railway line as a whole.

[0024] As a further improvement of the above scheme, the step S12 is also included, in which a rope is passed through a hole through drilling, and a rope saw is used to cut and remove the cantilevered part of the top plate of the old frame bridge.

[0025] As a further improvement of the above scheme, it also includes step S13, based on the reserved cutting holes, using a rope saw to cut and remove the plain concrete strip foundation and the old frame bridge bottom plate piece by piece until the demolition is completed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The method for dismantling an old frame bridge under a railway operating line of the present invention abandons the traditional construction method of simply cutting with a rope saw or simply ejecting the entire bridge, and solves the problem that the width of the old frame bridge is so large that the widest D-type temporary beam cannot be installed on its upper part. The advantages of various construction methods complement each other, reasonably solve the construction problems, and are highly operable.

[0028] 2. The method for dismantling an old frame bridge under a railway operating line of the present invention, wherein a newly-built strip foundation inside the frame bridge mainly bears pressure and basically does not consider the influence of bending moment, so there is no need to set stress reinforcement (only a steel mesh is hung on the outside). It is a plain concrete structure with simple construction and low overall cost.

[0029] 3. The method for dismantling an old frame bridge below a railway operating line of the present invention adopts a construction method of partial cutting and overall ejecting of the remaining part for dismantling the old frame bridge, which promptly frees up construction space for the subsequent ejection of a new frame bridge. The construction period is short, the impact on the operating railway above is small, and the construction safety is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the structure of pouring concrete in the old frame bridge to form a strip foundation in step S1 of the old frame bridge dismantling method provided in Example 1 of the present invention;

[0031] Figure 2 A schematic diagram of the structure of reinforcing the existing track with a D-type temporary beam in step S2 of the method for dismantling an old frame bridge provided in Example 1 of the present invention;

[0032] Figure 3 A schematic diagram of the structure of the slope excavation on both sides of the old frame bridge in step S3 of the method for dismantling the old frame bridge provided in Example 1 of the present invention;

[0033] Figure 4 A schematic diagram of the structure of using temporary support 7 to reinforce the old frame bridge and cutting the end of the top plate of the old frame bridge in steps S4 and S5 of the method for dismantling the old frame bridge provided in Example 1 of the present invention;

[0034] Figure 5 A schematic diagram of the structure of cutting the side wall of the old frame bridge in step S5 of the method for dismantling the old frame bridge provided in Example 1 of the present invention;

[0035] Figure 6A schematic diagram of the structure of cutting the end of the bottom plate of the old frame bridge in step S5 of the method for dismantling the old frame bridge provided in Example 1 of the present invention;

[0036] Figure 7 A schematic diagram of the structure of excavating pile holes in step S6 of the method for dismantling an old frame bridge provided in Example 1 of the present invention;

[0037] Figure 8 A schematic diagram of the structure of pouring a pile foundation in step S7 of the method for dismantling an old frame bridge provided in Example 1 of the present invention;

[0038] Fig. 9 A schematic diagram of the structure of casting a strip foundation on top of the pile foundation in step S8 of the method for dismantling an old frame bridge provided in Example 1 of the present invention;

[0039] Fig.10 A schematic diagram of the structure of the temporary beam conversion and reinforcement of the existing track in step S9 of the old frame bridge dismantling method provided in Example 1 of the present invention;

[0040] Fig.11 A schematic diagram of the structure of integrally ejecting the remaining part of the old frame bridge in step S10 of the method for dismantling the old frame bridge provided in Example 1 of the present invention;

[0041] Fig.12 A schematic diagram of a structure for removing temporary supports in an old frame bridge in step S11 of the method for dismantling an old frame bridge provided in Example 2 of the present invention;

[0042] Fig.13 A schematic diagram of the structure of cutting both ends of the top plate of the old frame bridge in step S12 of the method for dismantling the old frame bridge provided in Example 2 of the present invention;

[0043] Fig.14 A schematic diagram of the structure of the strip foundation and the remaining parts cut step by step in step S13 of the method for dismantling an old frame bridge provided in Example 2 of the present invention;

[0044] Fig.15 A schematic cross-sectional structure diagram of a temporary support in an uninstalled state in a method for dismantling an old frame bridge provided in Example 4 of the present invention;

[0045] Fig.16 for Fig.15 A schematic diagram of the structure of the central synchronizing shaft, the limit groove, the limit block and the first spring;

[0046] Fig.17 for Fig.15 A schematic diagram of the cross-sectional structure of the temporary support when the height is adjusted;

[0047] Fig.18 for Fig.15 Schematic diagram of the cross-sectional structure of the temporary support after height adjustment.

[0048] Description of main symbols:

[0049] 1. Old frame bridge; 2. Plain concrete strip foundation; 3. Cutting hole; 4. Independent pier; 5. D-type temporary beam; 6. Excavation and slope; 7. Temporary support; 8. Cutting and removing part; 9. Pile hole; 10. Pile foundation; 11. Reinforced concrete strip foundation; 12. Track surface; 13. Ground; 14. Pressure plate; 15. Top plate; 16. Rack; 17. Toothless gear; 18. Rocker; 19. Synchronous shaft; 20. Limiting groove; 21. Limiting block; 22. First spring; 23. L-shaped rod; 24. Block; 25. Second spring. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0051] Example 1

[0052] This embodiment provides a method for dismantling an old frame bridge under a railway operating line, which is applicable to the dismantling of an old frame bridge under a railway operating line where the width of the old frame bridge 1 is large, so that the pile foundation and strip foundation constructed on the outer side of the outer wall of the old frame bridge 1 cannot be used to build a common type of D-type temporary beam. The dismantling method specifically includes the following construction steps:

[0053] S1. Formwork is supported in the middle of the old frame bridge 1, and concrete is poured to form a plain concrete strip foundation 2. A steel mesh is hung on the outside of the plain concrete strip foundation 2 and anchored into the top plate and bottom plate of the old frame bridge 1. Cutting holes 3 for later cutting are evenly embedded in the plain concrete strip foundation 2, such as Figure 1 As shown;

[0054] The newly built plain concrete strip foundation 2 inside the frame bridge is mainly used to bear pressure, and the influence of bending moment is basically not considered, so there is no need to set stress reinforcement (only hang steel mesh on the outside). It is a plain concrete structure with simple construction and low overall cost.

[0055] S2. According to the specifications of the D-shaped temporary beam 5, an independent pier 4 is constructed at the corresponding position, so that the D-shaped temporary beam 5 is erected between the top plate of the frame bridge and the independent pier 4 directly above the plain concrete strip foundation 2, and the corresponding railway track is reinforced, such as Figure 2 As shown;

[0056] S3, excavate and slope the soil outside the outer wall of the old frame bridge 1 to form an excavation and slope surface 6, and hang steel mesh and sprayed concrete for protection, such as Figure 3 As shown;

[0057] S4, use temporary support 7 to reinforce the top plate inside the old frame bridge 1, such as Figure 4 shown.

[0058] S5, drill holes and pass ropes through them, and use rope saws to cut and remove the connection between the top plate and the side wall of the old frame bridge 1, such as Figure 4 As shown;

[0059] After the connection between the top plate and the side wall of the old frame bridge 1 is cut and removed, both ends of the top plate become cantilevered, so it is necessary to add temporary supports 7 to improve the stress state of the top plate and ensure the safety of the frame bridge.

[0060] Use a circular saw to cut and remove the side walls on both sides of the old frame bridge 1, such as Figure 5 As shown;

[0061] Through drilling holes and passing ropes, a rope saw is used to cut and remove the connection between the bottom plate and the side wall of the old frame bridge 1, such as Figure 6 As shown;

[0062] S6. Under the bottom plate of the old frame bridge 1 removed in the previous step, a plurality of pile holes 9 are formed by manual digging, such as Figure 7 As shown;

[0063] S7, for each pile hole 9, successively hang the steel cage, support the formwork above the ground, and pour concrete to form the pile foundation 10, such as Figure 8 As shown;

[0064] S8, on the same side, the top of the pile foundation 10 is supported by formwork, steel bars are tied, and concrete is poured to form a reinforced concrete strip foundation 11, such as Fig. 9 As shown;

[0065] S9, use the temporary beam conversion method to set up D-shaped temporary beams 5 between two reinforced concrete strip foundations 11 and between the reinforced concrete strip foundation 11 and the independent pier 4, and reinforce the corresponding railway tracks, such as Fig.10 As shown;

[0066] S10, using the poured new frame bridge as support, the remaining part of the old frame bridge 1 and the plain concrete strip foundation 2 inside are pushed out and removed as a whole, such as Fig.11 As shown;

[0067] In step S10, the old frame bridge 1 is dismantled by a construction method of partial cutting and overall ejecting of the remaining parts.

[0068] After the old frame bridge 1 is pushed out, the space is freed up, and the new frame bridge can be pushed into place according to the conventional construction method. The proposed construction method abandons the traditional construction method of simple rope saw cutting or simple overall push-out in the demolition of the old frame bridge, and solves the problem that the width of the old frame bridge is too large to cross the widest D-type beam on its upper part. The advantages of various construction methods complement each other, reasonably solve the construction problems, and have strong operability.

[0069] Example 2

[0070] The removal method of this embodiment further includes the following steps based on the first embodiment:

[0071] Step S11: After the old frame bridge 1 is pushed out of the safety range of the railway line, the temporary support 7 is removed. Fig.12 shown.

[0072] After the old frame bridge 1 has been pushed out of the safe range of the railway line as a whole, the subsequent demolition and dismantling work will have no impact on the adjacent operating lines, and the safety risks have been greatly reduced.

[0073] The old frame bridge is dismantled by partial cutting and overall jacking out of the remaining parts, which promptly frees up construction space for the subsequent jacking up of the new frame bridge. The construction period is short, the impact on the operating railway above is small, and the construction safety is high.

[0074] Step S12: drill holes, thread ropes, and use rope saws to cut and remove the cantilevered parts of the top plate of the old frame bridge 1, such as Fig.13 The cut-away portion 8 of the overhang of the top deck of the old frame bridge 1 can be seen.

[0075] Step S13: Based on the reserved cutting holes 3, a rope saw is used to cut and remove the plain concrete strip foundation 2 and the bottom plate of the old frame bridge 1 piece by piece until the demolition is completed. Fig.14 shown.

[0076] Example 3

[0077] This embodiment is an implementation case of embodiment 1 and embodiment 2 in reality, specifically the Shuangfeng Road underpass of Hefei City, Anhui Province, the Hefu Railway, Hefei-Bengbu Passenger Dedicated Line, and Huainan Line Project. The Shuangfeng Road expansion road adopts an (8+12+12+8)m box structure to underpass the Huainan Line. The box structure is referred to as box 1-box 4 from north to south. The width of box 1 and box 4 is 8m; the width of box 2 and box 3 is 12m; among them, the total length of box 1, box 2, and box 4 is 23.9m, and the total length of box 3 is 23.93m. The existing Huainan Line at the bridge site of this project is an electrified railway, the rails are seamless P60 rails, the straight roadbed section, the line spacing is 4 to 5.5m, and the section underpassing the Huainan Line is located between Shuangdunji Station and Dabaoying Line Station. This section of the railway is an electrified railway, and the line train operation density is high, about one train every 10 minutes, and the number of trains passing through every day is about 123 (pairs).

[0078] The old frame bridge (external width 16.1m) is located at the railway mileage K85+036.8. The height limit frames are set on both sides of the box body. The box culvert is 6.2m high, the top plate thickness is 0.65m, and the height limit is 4.3m. The above construction method is used to dismantle the old frame bridge. Some specific parameters are as follows:

[0079] ① The plain concrete strip foundation 2 of the supporting project has dimensions of 3.0m (width) × 4.85m (height) × 12.12m (length), the concrete grade is C20, a φ16@150 steel mesh is hung on the outside, and the cutting holes 3 are evenly distributed in two rows vertically with a horizontal spacing of 2.0m.

[0080] ② The implementation case relies on the independent pier 4 of the project with a size of 1.5m (width) × 0.6m (height) × 2.5m (length) reinforced concrete structure.

[0081] ③ Implementation case: The slope of the excavation and slope surface 6 of the project is 1:075. After excavation, 10cm thick C20 fine stone concrete is used to cast the slope surface in time, and φ8@100 steel mesh is installed.

[0082] ④ Implementation case The temporary support 7 of the supporting project is supported by φ609 steel pipes with a spacing of 1.5m. The rope saw cutting can be carried out only after the ballast within the diamond rope path is cleaned up. First cut the upper part of the side wall and the top plate, cut the transverse seam every 2m, and cut it into 3.0m×1.0m×0.7m blocks.

[0083] ⑤ Implementation case The diameter of the bored piles in the project is 1.5m, and 3 piles are evenly set on one side. There are 6 piles on both sides.

[0084] ⑥The implementation case relies on the pile foundation 10 of the project with a length of 18.0m.

[0085] ⑦ The reinforced concrete strip foundation 11 of the implementation case project has dimensions of 2.5m (height) × 2.0m (width) × 14.0m (length).

[0086] Advantages after implementation: The proposed construction method abandons the traditional construction method of simple rope saw cutting or simple overall ejection in the demolition of old frame bridges, and solves the problem that the width of the old frame bridge is too large to be able to span the widest D-type temporary beam on its upper part. The advantages of various construction methods complement each other, reasonably solve the construction problems, and have strong operability; the newly built strip foundation located inside the frame bridge mainly functions to bear pressure, and basically does not consider the influence of bending moment, so there is no need to set stress reinforcement (only hang steel mesh on the outside), which is a plain concrete structure with simple construction and low comprehensive cost; the demolition of the old frame bridge adopts the construction method of partial cutting and overall ejection of the remaining part, which promptly makes room for the subsequent jacking of the new frame bridge, with a short construction period, little impact on the operating railway above, and high construction safety.

[0087] Example 4

[0088] Please combine Figures 15 to 18 This embodiment is a preferred solution of the temporary support 7 in Embodiment 1, specifically, the temporary support 7 is an integrally erected columnar structure with a hollow interior. The bottom of the temporary support 7 is used to be placed on the top surface of the inner bottom plate of the old frame bridge 1, and a pressure plate 14 for supporting and lifting the inner top plate of the old frame bridge 1 is suspended above the temporary support 7. An adjusting device for adjusting the height of the pressure plate 14 is provided inside the temporary support 7. The height of the temporary support 7 can be adjusted in time according to the distance between the inner top plate and the bottom plate of the old frame bridge 1, so as to support and install the temporary support 7 between the inner top plate and the bottom plate of the old frame bridge 1 in an adaptive manner, which is convenient and quick.

[0089] The adjusting device includes a top plate 15 inserted on the top of the temporary support 7. The top of the top plate 15 is fixed to the bottom of the pressure plate 14, and the bottom extends into the temporary support 7. A rack 16 parallel to its moving direction is provided on the outer wall of the top plate 15 located in the temporary support 7.

[0090] A limit groove 20 perpendicular to the rack 16 is provided on one side of the temporary support 7, a limit block 21 is slidably connected in the limit groove 20, and the limit block 21 is connected to the corresponding groove wall of the limit groove 20 on the side close to the rack 16 through a first spring 22. A synchronous shaft 19 perpendicular to the moving direction of the limit block 21 is rotatably inserted, and the synchronous shaft 19 is perpendicular to the rack 16. A toothless gear 17 matching the rack 16 is sleeved and fixed on the outer side of the synchronous shaft 19.

[0091] The gear teeth of the toothless gear 17 are close to one side of the rack 16, and the toothless part is fixedly connected to the swing rod 18, and the free end of the swing rod 18 extends to the outside of the temporary support 7. In this embodiment, when the first spring 22 is not deformed, the gear teeth of the toothless gear 17 are not in contact with the rack 16. When the pressure plate 14 needs to be raised, the toothless gear 17 and the synchronous shaft 19 are first driven by the swing rod 18 to move the limit block 21 in the limit groove 20 toward the rack 16 (the first spring 22 is compressed and deformed), so that the gear teeth of the toothless gear 17 are in contact with the rack 16, and then the toothless gear 17 is driven to rotate by the swing rod 18, so that the gear teeth of the toothless gear 17 are engaged to drive the rack 16 and the top plate 15 to move upward, thereby driving the pressure plate 14 to move upward. In order to keep the height of the pressure plate 14 stable after the height adjustment, a self-locking mechanism is installed on the temporary support 7 in this embodiment, that is, after the toothless gear 17 rotates, the self-locking mechanism can timely complete the locking of the rising height of the pressure plate 14. When the self-locking mechanism is locked, the position of the toothless gear 17 in the circumferential and horizontal directions is reset through the swing rod 18, and the above operation is repeated again to adjust the height of the pressure plate 14 in coordination with the rack 16 until the pressure plate 14 is adjusted to contact the internal top plate of the old frame bridge 1.

[0092] The self-locking mechanism includes an L-shaped rod 23 located below the toothless gear 17. The vertical section of the L-shaped rod 23 is located inside the temporary support 7, the horizontal section extends outside the temporary support 7, and the end of the horizontal section is connected to the outer wall of the temporary support 7 through a second spring 25.

[0093] Specifically, a rotating shaft (not shown) is rotatably inserted at the bend of the L-shaped rod 23, and the two ends of the rotating shaft are fixedly inserted at both sides of the inner wall of the temporary support 7, so that the L-shaped rod 23 can rotate relative to the temporary support 7 around the rotating shaft to achieve force transmission. A clamping block 24 is provided on the side of the vertical section of the L-shaped rod 23 close to the rack 16. When the pressure plate 14 does not move, the clamping block 24 is clamped between the two teeth at the corresponding position on the rack 16 to prevent the rack 16 from moving, so that the pressure plate 14 remains stable (the second spring 25 is in a compressed state at this time).

[0094] In this embodiment, the side of the clamping block 24 facing the pressure plate 14 is flat and has an anti-slip texture to increase the static friction between the clamping block 24 and the teeth of the rack 16 in contact therewith, so as to ensure the stability of the clamping block 24 clamping the rack 16 .

[0095] The block 24 has an inclined surface (not shown) on the side away from the pressure plate 14, and the inclined surface is smoothed so that when the rack 16 moves upward, the tooth body located below the block 24 and about to contact can slide and squeeze the block 24 through the inclined surface to skip the block 24 and avoid interfering with the continuous upward movement of the rack 16. When the inclined surface contacts and slides to squeeze the block 24, it will drive the L-shaped rod 23 to rotate and further squeeze the second spring 25. When the pressure plate 14 moves to the specified height, the rack 16 no longer moves. At this time, the elastic force of the second spring 25 is released to allow the L-shaped rod 23 to drive the block 24 to re-enter between the corresponding two teeth on the rack 16, thereby locking the position of the pressure plate 14 after the height adjustment, so as to complete the installation support of the temporary support 7 between the top plate and the bottom plate inside the old frame bridge 1.

[0096] In this embodiment, when the temporary support 7 needs to be removed, it is only necessary to step on the horizontal section of the L-shaped rod 23 with the foot to force the second spring 25 to be further compressed, so that the block 24 is disengaged from the two corresponding teeth of the rack 16. Then, the pressure plate 14, the top plate 15 and the rack 16 will move downward under the action of gravity until they return to the initial position, saving removal time and being safe and convenient.

[0097] The innovative idea of ​​the present invention is obtained through innovation and reflection based on the difficulties and limitations of the actual old frame bridge demolition project, so that the demolition construction period of the old frame bridge is short, the impact on the upper operating railway is small, and the construction safety is high.

[0098] The accompanying drawings only show some working conditions and some implementation methods of the construction method. According to the proposed ideas, the dismantling order of the old frame bridge can be changed to form other related types of dismantling methods combining rope saw cutting and ejection. They are all equivalent modifications and changes of the present invention and will not be repeated here.

[0099] The accompanying drawings are only used for illustrative purposes and should not be construed as limitations on the present invention. In order to better illustrate the present embodiment, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings. The same or similar reference numerals correspond to the same or similar parts. The terms describing the positional relationship in the accompanying drawings are only used for illustrative purposes and should not be construed as limitations on the present invention.

[0100] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for dismantling an old frame bridge under a railway operating line, characterized in that: The steps include: S1. Formwork is supported in the middle of the old frame bridge, and concrete is poured to form a plain concrete strip foundation. A steel mesh is hung on the outside of the plain concrete strip foundation and anchored into the top and bottom plates of the old frame bridge; S2. construct independent piers at corresponding positions according to the specifications of the D-type temporary beam, so that the D-type temporary beam is erected between the top plate of the frame bridge and the independent piers directly above the plain concrete strip foundation, and reinforce the corresponding railway tracks; S3, excavate and slope the soil outside the outer wall of the old frame bridge to form an excavation and slope surface; S4, use temporary supports to reinforce the top plate inside the old frame bridge; S5, sequentially remove the connection parts between the top plate and the side wall of the old frame bridge, the side walls on both sides of the old frame bridge, and the connection parts between the bottom plate and the side wall of the old frame bridge; S6. Dig holes below the bottom plate of the old frame bridge to form multiple pile holes evenly distributed; S7, sequentially placing steel cages in each pile hole, supporting formwork above the ground, and pouring concrete to form a pile foundation; S8. Formwork is supported on the top of the pile foundation on the same side, steel bars are tied, and concrete is poured to form a reinforced concrete strip foundation; S9. Use the temporary beam conversion method to set up D-type temporary beams between two reinforced concrete strip foundations and between reinforced concrete strip foundations and independent piers to reinforce the corresponding railway tracks; S10. Based on the completed new frame bridge, the remaining part of the old frame bridge and the internal plain concrete strip foundation are pushed out and removed as a whole.

2. The method for dismantling an old frame bridge under a railway operating line according to claim 1, characterized in that: In step S1, cutting holes for later cutting are uniformly embedded in the concrete strip foundation.

3. The method for dismantling an old frame bridge under a railway operating line according to claim 1, characterized in that: In step S3, steel mesh and shotcrete are hung on the slope for protection.

4. The method for dismantling an old frame bridge under a railway operating line according to claim 1, characterized in that: In step S5, holes are drilled and ropes are passed through, and a rope saw is used to cut and remove the connection between the top plate and the side wall of the old frame bridge and the connection between the bottom plate and the side wall of the old frame bridge.

5. The method for dismantling an old frame bridge under a railway operating line according to claim 1, characterized in that: In step S5, a circular saw is used to cut and remove the side walls on both sides of the old frame bridge.

6. The method for dismantling an old frame bridge under a railway operating line according to claim 1, characterized in that: In step S6, a manual hole digging construction method is adopted to form a plurality of pile holes that are evenly distributed.

7. The method for dismantling an old frame bridge under a railway operating line according to claim 1, characterized in that: In step S10, the old frame bridge is dismantled by a construction method of partial cutting and overall ejecting of the remaining parts.

8. The method for dismantling an old frame bridge under a railway operating line as claimed in claim 2, characterized in that: The method further comprises step S11, after the old frame bridge is pushed out as a whole to outside the safety range of the railway line, the temporary support is removed.

9. The method for dismantling an old frame bridge under a railway operating line as claimed in claim 8, characterized in that: The method also includes step S12, drilling holes, threading ropes, and using a rope saw to cut and remove the cantilevered portion of the top plate of the old frame bridge.

10. The method for dismantling an old frame bridge under a railway operating line according to claim 9, characterized in that: The method also includes step S13, using a rope saw to cut and remove the plain concrete strip foundation and the old frame bridge bottom plate piece by piece based on the reserved cutting holes until the demolition is completed.

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