Method for dismantling girder of cable-stayed bridge with less stress in support stage

Abstract

According to the cable-stayed bridge girder dismantling method with less stress in the support stage, staged stay cables are released step by step, then girder cutting is conducted in a staged mode, the dead weight of the girder is released by releasing the oblique tension of the stay cables on the girder, and the girder is demolished. Partial self-weight of the main beam is released in each stage, partial load of the main beam is transferred to the support system below the main beam from the inhaul cable, partial structure of the main beam is cut after release in each stage, and the self-weight of the cut partial structure of the main beam corresponds to the partial self-weight of the released main beam; and in the last stay cable releasing stage, all cable force is released, the residual self-weight load of the main beam is completely transferred to a support system below the main beam, and then the residual structure of the main beam is cut in a segmented mode. The method is applied to dismantling of the main beam of the cable-stayed bridge, staged step-by-step releasing and tensioning of the stay cable are utilized, loads are transmitted to a dismantling support step by step, a main beam structure is cut off step by step, the purpose of reducing stress of the support is achieved, and therefore the input amount of the support is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of bridge construction, and in particular to a method for dismantling a main beam of a cable-stayed bridge subjected to less stress during a support stage. Background Art

[0002] A cable-stayed bridge, also known as a cable-stayed bridge, is a bridge in which the main beam 10 is directly pulled to the bridge tower by many cables. It is a structural system composed of compression towers, tension cables and bending beams.

[0003] A cable-stayed bridge is a bridge in which a main beam 10 is supported on towers 30 by several stay cables 20. It consists of three parts: the main beam 10, the stay cables 20, and the towers 30. A cable-stayed bridge is a self-anchored system, where the horizontal force of the stay cables 20 is borne by the beam. In addition to being supported by piers, the beam is also supported by the stay cables 20 extending from the towers 30.

[0004] Common cable-stayed bridge main beam 10 dismantling processes include blasting, hanging basket dismantling, in-situ demolition, scaffolding and segmented cutting of existing beams, and crane cutting in small sections. Each process has its own characteristics, advantages and disadvantages: blasting is suitable for mountainous areas, areas with few surrounding residents, and areas insensitive to the surrounding environment, but not suitable for areas with dense populations, adjacent to scenic spots, and downtown areas; hanging basket dismantling is suitable for the demolition of bridges in relatively good condition, but not suitable for dangerous bridges; in-situ demolition is suitable for the demolition of low-lying land bridges with few surrounding residents and little noise impact; the scaffolding method of whole-section demolition is suitable for the demolition of all types of main beams 10. Under the condition of bridge bottom height limit, the amount of scaffolding required is large; the crane small-piece cutting method is suitable for the demolition of bridges in good health.

[0005] There are many problems in dismantling the main beam 10 of a cable-stayed bridge with limited space at the bottom of the bridge, such as low efficiency of the bracket for setting up and dismantling the main beam 10, large span of the bracket designed outside the projection line of the main beam 10, etc. Moreover, if the bracket system needs to bear the load of the entire section of the main beam 10, then the load-bearing system requirements will be particularly high, which will cause a particularly large material investment. At the same time, there are problems such as low installation efficiency and extremely high cost. Therefore, we need to control the bracket force during the dismantling process and reduce the requirements for the bracket system.

[0006] In the above context, the applicant has proposed a new solution for dismantling the main beam 10 of a cable-stayed bridge. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for dismantling the main beam of a cable-stayed bridge with reduced stress at the support stage. The method utilizes the stepwise tensioning of the stay cables to control the stress on the support and dismantle the main beam in small sections. The technical solutions employed include:

[0008] A method for dismantling the main beam of a cable-stayed bridge with less stress at the support stage comprises: gradually tensioning the stay cables in stages, then cutting the main beam in stages, releasing the self-weight of the main beam by releasing the oblique tension of the stay cables on the main beam, releasing part of the self-weight of the main beam in each stage, transferring part of the load of the main beam from the cables to the support system below the main beam, and cutting part of the main beam structure after each stage of release, wherein the self-weight of the cut main beam structure corresponds to the released part of the self-weight of the main beam; in the last stay cable tensioning stage, all the cable forces are released, transferring all the load of the remaining self-weight of the main beam to the support system below the main beam, and then cutting the remaining structure of the main beam in sections.

[0009] According to an embodiment of the present invention, a method for dismantling a main beam of a cable-stayed bridge with less stress in the support stage includes a dismantling stage, which includes the following steps:

[0010] S1. Release 30% of the main beam's deadweight by releasing the diagonal tension of the stay cables on the main beam, and transfer 30% of the main beam's deadweight to the support system below the main beam;

[0011] S2. Cut the flange plate and inclined web of the main beam;

[0012] S3. Release 30% of the main beam's deadweight by releasing the diagonal tension of the stay cables on the main beam, and transfer 30% of the main beam's deadweight to the support system below the main beam;

[0013] S4, cutting the beams on both sides of the main beam;

[0014] S5. Release all remaining cable forces in the stay cables and transfer all remaining deadweight loads of the main beam to the support system below the main beam.

[0015] S6. Cut the remaining structure of the main beam supported on the support system into sections.

[0016] According to an embodiment of the present invention, a method for dismantling a main beam of a cable-stayed bridge with less stress in the support stage further includes a support system support stage before the dismantling stage, which includes the following steps:

[0017] S10. Drive steel pipe piles into the area outside the projection line directly below the main beam as a temporary support foundation;

[0018] S20, erecting a steel truss beam on top of the steel pipe pile to form a load-bearing platform spanning the main beam;

[0019] S30. Install a pressure ring and a beam bottom support pad at the fulcrum where the steel truss beam contacts the main beam, ensuring close contact between the main beam, the pressure ring and the beam bottom support pad;

[0020] S40, cutting off the joint end of the main beam to form a double cantilever structure. At this time, the main beam extends to both sides with the tower column as the center to form a cantilever;

[0021] S50. Select the stay cable on the side with the longest cantilever, install a through-hole jack at the anchor end of the stay cable at the top of the tower, and connect it to a pressure sensor.

[0022] According to a method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to an embodiment of the present invention, in step S2, the flange plate and the inclined web plate are cut with a wire saw, and both sides must be cut off simultaneously.

[0023] According to a method for dismantling a main beam of a cable-stayed bridge with less stress during the support stage according to an embodiment of the present invention, in step S3, when releasing the tension of the stay cables, the stress on the pressure ring must be observed and fine-tuned to ensure that the stress is even.

[0024] According to a method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to an embodiment of the present invention, in step S4, the outer webs on both sides of the main beam and the bottom plates connected thereto are simultaneously removed.

[0025] According to a method for dismantling a main beam of a cable-stayed bridge with less stress in the support stage according to an embodiment of the present invention, in step S6, the cutting of the remaining structure of the main beam must be segmented and symmetrical.

[0026] According to an embodiment of the present invention, a method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage requires symmetrical unloading when tensioning the cable stays at each stage, with the cables on both sides being tensioned alternately from the mid-span toward the bridge tower.

[0027] According to a method for dismantling a main beam of a cable-stayed bridge with less stress in a support stage according to an embodiment of the present invention, the beam bottom support pad is a steel plate or a rubber pad.

[0028] According to an embodiment of the present invention, a method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage includes, in step S40, setting temporary supports on both sides of the joint section to be removed; and using a diamond wire saw to remove the concrete or steel joint section in sections.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention is applied to the dismantling of the main beam of a cable-stayed bridge, making full use of the advantage of graded unloading of the cable-stayed cable, which can greatly reduce the stress on the bracket at each stage, and at the same time use the pressure ring to accurately read the load transferred to the bracket, so as to achieve precise control of the stress on the cable and the stress on the bracket, and then cut in sections, thereby replacing the conventional large-segment removal, in which all the loads are transferred to the beam storage bracket. The bracket is difficult to install under the limited space at the bottom of the bridge, the span of the projected outer side pile driving is large, and the investment in the steel structure of the load-bearing system increases dramatically. The present invention uses the cable-stayed cable to be tensioned step by step in stages, and the load is transferred step by step to the dismantling bracket, and the main beam structure is removed in stages, so as to achieve the purpose of reducing the stress on the bracket, thereby reducing the investment in the bracket. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0032] Figure 1 This is a schematic diagram of the support stage of the bracket system in the embodiment of the present application;

[0033] Figure 2 This is a schematic diagram of the demolition stage in the embodiment of this application Figure 1 ;

[0034] Figure 3 This is a schematic diagram of the demolition stage in the embodiment of this application Figure 2 ;

[0035] Figure 4 This is a schematic diagram of the demolition stage in the embodiment of this application Figure 3 .

[0036] Description of main component symbols:

[0037] 10. Main beam; 11. Flange plate; 12. Diagonal web; 13. Outer web; 14. Bottom plate; 20. Stay cable; 30. Tower column; 40. Steel pipe pile; 50. Steel truss beam; 60. Pressure ring. DETAILED DESCRIPTION

[0038] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0039] In the description of this invention, "above," "below," and "within" are understood to be exclusive of the number indicated. The terms "first" and "second" are used solely to distinguish technical features and are not to be construed as indicating or implying relative importance, or as implicitly specifying the number or order of the technical features indicated.

[0040] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0041] In the present invention, unless otherwise expressly defined, terms such as "disposed," "installed," and "connected" should be interpreted broadly. For example, they may refer to direct connection or indirect connection through an intermediate medium; fixed connection or detachable connection or integral molding; mechanical connection; and internal communication between two components or interaction between two components. Those skilled in the art can reasonably determine the specific meanings of these terms in the present invention based on the specific content of the technical solution.

[0042] A method for dismantling the main girder of a cable-stayed bridge with less stress during the support stage comprises gradually releasing the stay cables 20 in stages, then cutting the main girder 10 in stages. The self-weight of the main girder 10 is released by releasing the diagonal tension of the stay cables 20 on the main girder 10. In each stage, a portion of the self-weight of the main girder 10 is released, transferring part of the load of the main girder 10 from the cables to the support system below the main girder 10. After each stage of release, a portion of the main girder 10 structure is cut, and the self-weight of the cut portion of the main girder 10 structure corresponds to the released portion of the self-weight of the main girder 10. In the last stage of tensioning the stay cables 20, all cable forces are released, transferring the remaining self-weight of the main girder 10 to the support system below the main girder 10, and then the remaining structure of the main girder 10 is cut in sections. During each stage of tensioning the stay cables 20, the unloading must be symmetrical, with the cables on both sides being alternately tensioned from the mid-span toward the bridge tower.

[0043] The following is a detailed description through specific embodiments and accompanying drawings:

[0044] A method for dismantling the main beam of a cable-stayed bridge with less stress in the support stage, such as Figure 1 、 2 , 3, and 4, including the support system support stage and the removal stage, in which

[0045] The support stage of the support system includes the following steps:

[0046] S10, driving steel pipe piles 40 into the area outside the projection line directly below the main beam 10 as a temporary support foundation;

[0047] S20, erecting a steel truss beam 50 on top of the steel pipe pile 40 to form a load-bearing platform spanning the main beam 10;

[0048] S30, setting a pressure ring 60 and a beam bottom support pad at the fulcrum position where the steel truss beam 50 contacts the main beam 10, ensuring that the main beam 10 is in close contact with the pressure ring 60 and the beam bottom support pad; the beam bottom support pad is a steel plate or a rubber pad;

[0049] S40, cutting off the joint end of the main beam 10 so that the main beam 10 forms a double cantilever structure (such as Figure 1As shown), at this time, the main beam 10 extends to both sides with the tower column 30 as the center to form a cantilever; before cutting, temporary supports are set on both sides of the joint section to be cut, and the concrete or steel joint section is removed in sections using a diamond wire saw to avoid vibration disturbance;

[0050] S50: Select the inclined cable 20 on the side with the longest cantilever, install a through-hole jack at the anchoring end of the inclined cable 20 at the top of the tower, and connect it to a pressure sensor.

[0051] The dismantling phase includes the following steps:

[0052] S1. Release 30% of the main beam 10's deadweight by releasing the oblique tension of the stay cables 20 on the main beam 10, and transfer 30% of the deadweight of the main beam 10 to the support system below the main beam 10.

[0053] S2, cutting the flange plate 11 and the inclined web 12 of the main beam 10, cutting the flange plate 11 and the inclined web 12 with a rope saw, and cutting both sides at the same time (such as Figure 2 As shown, the black part in the figure is the cutting part);

[0054] S3. Release 30% of the main beam 10's deadweight by releasing the diagonal tension of the stay cables 20 on the main beam 10. Transfer 30% of the deadweight of the main beam 10 to the support system below the main beam 10. When releasing the force of the stay cables 20, observe the force on the pressure ring 60 and make fine adjustments to ensure that the force is evenly distributed.

[0055] S4, cutting the beams on both sides of the main beam 10, specifically, cutting the outer webs 13 on both sides of the main beam 10 and the bottom plates 14 connected thereto (such as Figure 3 As shown, the black part in the figure is the cutting part);

[0056] S5, release all the remaining cable forces of the stay cable 20, and transfer all the remaining deadweight load of the main beam 10 to the support system below the main beam 10 (such as Figure 4 shown);

[0057] S6. Cut the remaining structure of the main beam 10 supported on the support system into sections, and the sections must be cut symmetrically and synchronously.

[0058] The present invention is applied to the dismantling of the main beam 10 of a cable-stayed bridge, making full use of the advantage of the graded unloading of the inclined cables 20, which can greatly reduce the stage-by-stage stress of the bracket. At the same time, the pressure ring 60 is used to accurately read the load transferred to the bracket, so as to realize the precise control of the stress of the inclined cables 20 and the stress of the bracket, and then cut in sections, thereby replacing the conventional large-segment removal and transferring all the loads to the beam storage bracket. The bracket is difficult to install under the limited space at the bottom of the bridge, the span of the projected outer side pile driving is large, and the investment in the steel structure of the load-bearing system increases dramatically. The present invention uses the inclined cables 20 to release the tension step by step in stages, and the load is transferred to the dismantling bracket step by step, and the main beam 10 structure is removed in stages, so as to achieve the purpose of reducing the stress on the bracket, thereby reducing the investment in the bracket.

[0059] Of course, the present invention is not limited to the above-mentioned embodiments. Those skilled in the art may make equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications and substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for dismantling the main beam of a cable-stayed bridge with less stress in the support stage, characterized in that: The inclined cables (20) are gradually tensioned, and then the main beam (10) is cut in stages. The deadweight of the main beam (10) is released by releasing the oblique tension of the inclined cables (20) on the main beam (10). In each stage, part of the deadweight of the main beam (10) is released to transfer part of the load of the main beam (10) from the cables to the support system below the main beam (10). After each stage of release, part of the structure of the main beam (10) is cut. The deadweight of the cut part of the structure of the main beam (10) corresponds to the released part of the deadweight of the main beam (10). In the last stage of tensioning the inclined cables (20), all the cable forces are released, and the load of the remaining deadweight of the main beam (10) is completely transferred to the support system below the main beam (10). Then, the remaining structure of the main beam (10) is cut in sections.

2. The method for dismantling the main beam of a cable-stayed bridge with less stress at the support stage according to claim 1 is characterized in that: There is a demolition phase, which includes the following steps: S1. releasing 30% of the deadweight of the main beam (10) by releasing the oblique tension of the inclined cable (20) on the main beam (10), and transferring 30% of the deadweight of the main beam (10) to the support system below the main beam (10); S2, cutting the flange plate (11) and the inclined web plate (12) of the main beam (10); S3, releasing 30% of the deadweight of the main beam (10) by releasing the oblique tension of the inclined cable (20) on the main beam (10), and transferring 30% of the deadweight of the main beam (10) to the support system below the main beam (10); S4, cutting the beam bodies on both sides of the main beam (10); S5, releasing all the remaining cable forces of the stay cables (20), and transferring all the remaining deadweight load of the main beam (10) to the support system below the main beam (10); S6. Cut the remaining portion of the main beam (10) supported on the support system into sections.

3. The method for dismantling the main beam of a cable-stayed bridge with less stress at the support stage according to claim 2 is characterized in that: Before the dismantling stage, there is also a support system support stage, which includes the following steps: S10, driving steel pipe piles (40) into the area outside the projection line directly below the main beam (10) as a temporary support foundation; S20, erecting a steel truss beam (50) on top of the steel pipe pile (40) to form a load-bearing platform spanning the main beam (10); S30, setting a pressure ring (60) and a beam bottom support pad at the fulcrum position where the steel truss beam (50) contacts the main beam (10), ensuring that the main beam (10) is in close contact with the pressure ring (60) and the beam bottom support pad; S40, cutting off the joint end of the main beam (10), so that the main beam (10) forms a double cantilever structure. At this time, the main beam (10) is centered on the tower column (30) and extends to both sides to form cantilevers; S50, selecting the inclined cable (20) on the side of the longest cantilever, installing a through-hole jack at the anchoring end of the inclined cable (20) at the top of the tower, and connecting a pressure sensor.

4. The method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to claim 2 is characterized in that: In step S2, the flange plate (11) and the inclined web plate (12) are cut with a wire saw, and both sides must be cut off simultaneously.

5. The method for dismantling the main beam of a cable-stayed bridge with less stress at the support stage according to claim 2 is characterized in that: In step S3, when the cable force of the stay cable (20) is released, the force on the pressure ring (60) must be observed and fine-tuned to ensure that the force is even.

6. The method for dismantling the main beam of a cable-stayed bridge with less stress at the support stage according to claim 2 is characterized in that: In step S4, the outer webs (13) on both sides of the main beam (10) and the bottom plates (14) connected thereto are simultaneously cut away.

7. The method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to claim 2 is characterized in that: In step S6, the remaining portion of the main beam (10) is cut symmetrically in sections.

8. The method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to claim 1 is characterized in that: When the stay cables (20) are released at each stage, they must be unloaded symmetrically, and the cables on both sides must be released alternately from the mid-span toward the bridge tower.

9. The method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to claim 3 is characterized in that: The beam bottom support pad is a steel plate or a rubber pad.

10. The method for dismantling a main beam of a cable-stayed bridge with less stress at the support stage according to claim 3, characterized in that: In step S40, temporary supports are set on both sides of the joint section to be removed; and the concrete or steel joint section is removed in sections using a diamond wire saw, for example.

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