Hanging bracket closure structure close to business line and construction method

Abstract

The invention discloses a hanging bracket closure structure close to a business line and a construction method, and relates to the technical field of bridge construction, the hanging bracket closure structure comprises a bearing beam, a hanging basket track, a hanging bracket upper cross beam, a hanging basket outer side hanging belt, an outer guide beam, a hanging basket bottom cross beam and a totally-closed protection assembly; the bearing beam is laid and fixed on a bridge surface of a bridge body, the hanging basket track is fixedly connected to the top end of the bearing beam, and the hanging basket track reuses an original hanging basket walking track; s3, after the rotating body is in place, within the railway blocking point time, partial anchoring of the hanging bracket is removed, and the hanging bracket is driven to walk to the closure section design position along the track laid on the bridge floor and is anchored again; s4, locking of a stiff framework of a closure section, binding of steel bars and concrete pouring are completed in a totally-closed protection assembly arranged on the hanging bracket; and S5, after closure section construction is completed, within the railway blocking point time, the hanging bracket retreats to a safety area and then is dismantled.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a suspension closure structure and construction method for bridges located near operational railway lines. Background Technology

[0002] The mid-span closure of a continuous beam bridge near an operational railway line is a core and critical step in bridge engineering, directly determining the overall load-bearing performance and operational safety of the bridge. This type of construction must achieve three core objectives under complex conditions: first, ensuring uninterrupted safe operation of the existing railway below and avoiding interference with train scheduling; second, adapting to the strict construction time windows (limited track maintenance periods) and railway construction clearance requirements (typically 6.55m in height) of the operational railway line; and third, controlling structural deformation of the closure section to ensure the beam construction quality meets standards.

[0003] Currently, the three mainstream closure construction methods in the industry all have significant shortcomings, making it difficult to balance safety, efficiency, and cost requirements: First, the hanging basket method with a protective scaffold erected below requires a large investment in pipe rental and erection costs, has a lengthy construction cycle, and requires multiple applications for line closures, which not only seriously affects railway operation efficiency but also leads to a sharp increase in safety risks due to frequent high-altitude cross-operations; Second, the steel shell formwork method requires specific design calculations and change approvals for specific projects, which is time-consuming, has poor adaptability, and is difficult to adapt to different spans and clearance requirements; Third, the traditional hanging frame closure method, although relatively low in cost, has problems such as a high center of gravity of the hanging frame, an imperfect safety protection system, and insufficient precision in controlling structural deformation, and cannot effectively meet the core requirements of clearance protection and risk isolation for operating lines. Summary of the Invention

[0004] This invention provides a hanging frame closure structure for use near operating lines, which can solve the problem that existing closure construction methods have significant shortcomings and are difficult to balance safety, efficiency and cost requirements.

[0005] A suspension frame closure structure for use near operational lines includes a pad beam, a hanging basket track, an upper crossbeam of the suspension frame, outer hanging basket slings, an outer guide beam, a bottom hanging basket crossbeam, and a fully enclosed protective assembly. The pad beam is laid and fixed on the bridge deck of the bridge body. The hanging basket track is fixed to the top of the pad beam, and the hanging basket track reuses the original hanging basket travel track. The upper crossbeam of the suspension frame supports the hanging basket track. The outer hanging basket slings are vertically inserted and connected to the upper crossbeam of the suspension frame, and the bottom hanging basket crossbeam is horizontally connected to the bottom end of the outer hanging basket slings. The outer guide beam is fixedly connected below the hanging basket track and is adapted to the side formwork for pulling the side formwork forward in stages. The fully enclosed protective assembly is connected to the bottom of the bottom hanging basket crossbeam and the outside of the side formwork, forming a protective space without blind spots.

[0006] The present invention provides a suspension bracket closure structure for adjacent operating lines, which, compared with the prior art, has the following beneficial effects, but is not limited to: The adjacent operational line utilizes a gantry closure structure, with pad beams and reusing the original hanging basket tracks to form a stable and low-cost bridge deck walking foundation. The upper crossbeams of the gantry directly support the tracks, abandoning the traditional tall diamond trusses, significantly lowering the center of gravity and height of the entire gantry, improving its anti-overturning stability and wind resistance during bridge deck movement and operations, and effectively eliminating the risk of encroaching on railway construction clearances. The outer slings of the hanging basket and the bottom crossbeam of the hanging basket form a reliable suspended working platform, while the outer guide beam provides dedicated tracks and support for the step-by-step and precise forward movement of the side formwork system. Most importantly, the fully enclosed protective components connected to the bottom of the bottom crossbeam and the outside of the side formwork, together with the formwork that has undergone multiple sealing treatments, form a rigid enclosed space without blind spots, physically completely blocking any possibility of tools, materials, or concrete slurry falling or leaking during construction, providing a fundamental guarantee for the safe operation of the railway line below.

[0007] A method for constructing a gantry crane near an operational railway line includes the following steps: S1: After the T-shaped cantilever section is completed and before the rotation, the existing hanging basket and formwork on the mid-span side are modified to form a gantry, and the modified gantry is anchored to the beam on the mid-span side of the T-shaped structure; S2: The T-shaped structure with the gantry anchored is rotated into position; S3: After the rotation is in place, within the time limit for railway closure, the partial anchoring of the gantry is released, and it is driven to travel along the track laid on the bridge deck to the design position of the closure section and re-anchored; S4: Within the fully enclosed protective components set on the gantry, the stiffening frame of the closure section is locked, the steel bars are tied, and the concrete is poured; S5: After the closure section is completed, within the time limit for railway closure, the gantry is moved back to a safe area and dismantled.

[0008] This invention also provides a method for constructing a gantry-type closure system near an operational railway line, which, compared to existing technologies, has the following advantages, but is not limited to: The adjacent operational line adopted a gantry closure construction method, directly utilizing existing hanging baskets and formwork on site to create a dedicated gantry. This significantly reduced the cost of purchasing new materials and leasing equipment, demonstrating remarkable economic efficiency. The modified gantry was pre-anchored and rotated along with the T-structure, allowing the main installation work to be completed without railway interference, greatly improving construction efficiency and reserving time windows for critical steps. After rotation, the gantry was driven to precisely move and position itself along the bridge deck track within a brief railway closure point, strictly limiting high-risk operations to a controllable time period and minimizing the impact on the operation of the operational line below, demonstrating strong adaptability. The entire closure section operation was carried out within the fully enclosed protective components carried by the gantry. This structure fundamentally eliminated the risk of falling debris and concrete leakage during construction, providing absolutely reliable physical isolation protection for railway traffic safety.

[0009] Furthermore, in step S1, the modification using the existing hanging basket and formwork on the mid-span side includes: removing the diamond truss on the hanging basket and directly installing the crossbeam of the hanging basket's hanger onto the hanging basket track to lower the hanger's center of gravity.

[0010] Furthermore, in step S1, during the modification and anchoring of the hanger, counterweights are set on designated sections on both sides of the T-structure to ensure the torque balance of the T-structure.

[0011] Furthermore, in step S3, the driving of its movement is carried out by jacking; the movement process is implemented in steps, including first releasing the bottom basket anchorage of the gantry, lowering the slings to detach the formwork from the beam, and driving the bottom basket forward; then releasing and anchoring the side formwork in steps, and alternately pulling the side formwork and the outer guide beam forward.

[0012] Furthermore, in step S4, a synchronous weight-replacement method is used during concrete pouring to maintain the force balance of the cantilever on both sides of the closure joint.

[0013] Furthermore, the synchronous weight replacement is achieved through a counterweight water tank set at the cantilever end of the T-structure. The weight replacement is calculated based on the weight of the concrete in the closure section and the construction load, and the water stored in the water tank is discharged synchronously in proportion during the concrete pouring process.

[0014] Furthermore, in step S4, after the template is installed, expanding foam, double-sided tape, and transparent tape are used to seal the template joints in multiple ways.

[0015] Furthermore, in step S4, the stiffening frame is welded and locked during periods of low daily temperature; after the stiffening frame is installed, some of the longitudinal prestressed steel strands are pre-tensioned; the concrete used is early-strength micro-expansion concrete, which is one grade higher than that used in the beam.

[0016] Furthermore, in step S4, after the concrete of the closure section reaches its strength, the prestressed steel strands are tensioned in sequence to complete the system conversion. The sequence is as follows: first, some of the closure strands are pre-tensioned, then the stiffening frame is released, and finally all the remaining prestressed steel strands are tensioned. After tensioning is completed, the duct is grouted within a specified time. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a suspension bracket closure structure used in an embodiment of the present invention for a line adjacent to a service line. Figure 1 ; Figure 2 This is a schematic diagram of a suspension bracket closure structure used in an embodiment of the present invention for a line adjacent to a service line. Figure 2 ; Figure 3 This is a schematic diagram of the working process of a suspension bracket closure structure used in an embodiment of the present invention for a line adjacent to a service line; Figure 4This is a flowchart illustrating a method for constructing a closure scaffold near an operational railway line according to an embodiment of the present invention. Figure 5 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 1 ; Figure 6 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 2 ; Figure 7 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 3 ; Figure 8 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 4 ; Figure 9 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 5 ; Figure 10 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 6 ; Figure 11 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 7 ; Figure 12 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 8 ; Figure 13 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 9 ; Figure 14 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 10 ; Figure 15 This invention provides an embodiment of the construction of a suspension frame closure structure for a line adjacent to an operational railway line. Figure 10 one.

[0018] Explanation of reference numerals in the attached figures: 100. Hanging basket; 200. Formwork; 1. Pad beam; 2. Hanging basket track; 3. Upper crossbeam of the hanger; 4. Outer sling of the hanging basket; 5. Outer guide beam; 6. Bottom crossbeam of the hanging basket; 7. Fully enclosed protective components; 8. Bridge body; 9. Diamond truss; 10. Bottom basket; 11. Side formwork; 12. Counterweight water tank; 13. Counterweight block; 14. Railway track. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings showing multiple embodiments according to this application. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," etc., in the description, claims, and accompanying drawings of this application are open-ended terms. Therefore, "comprising," "including," or "having" refers to, for example, a method or apparatus having one or more steps or elements, but is not limited to having only these one or more elements. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.

[0024] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] like Figure 1-3 As shown, a suspension frame closure structure is used near the operational railway line and is set in the closure section construction area of ​​bridge body 8. It includes a pad beam 1, a hanging basket track 2, an upper crossbeam of the suspension frame 3, an outer hanging basket sling 4, an outer guide beam 5, a bottom hanging basket crossbeam 6, and a fully enclosed protective component 7. The pad beam 1 is laid and fixed on the bridge surface of bridge body 8. The hanging basket track 2 is fixed to the top of the pad beam 1, and the hanging basket track 2 reuses the original hanging basket travel track. The upper hanging basket crossbeam 3 is directly supported on the hanging basket track 2. The outer hanging basket sling 4 is vertically inserted and connected to the upper hanging basket crossbeam 3. The bottom hanging basket crossbeam 6 is horizontally connected to the bottom of the outer hanging basket sling 4. The outer guide beam 5 is fixedly connected to the bottom of the hanging basket track 2 and is adapted to the side formwork 11 for pulling the side formwork 11 forward in steps. The fully enclosed protective component 7 is connected to the bottom of the bottom hanging basket crossbeam 6 and the outside of the side formwork 11 to form a protective space without blind spots. The fully enclosed protective component 7 is located above the railway track 14.

[0026] In this embodiment, the pad beam 1 and the basket track 2, which reuses the original basket 100's travel track, together form a stable and low-cost bridge deck walking foundation. The upper crossbeam 3 of the gantry directly supports the basket track 2, eliminating the need for the traditional tall diamond truss 9, significantly lowering the center of gravity and height of the entire gantry, improving its anti-overturning stability and wind resistance during bridge deck movement and operation, and effectively eliminating the risk of encroaching on the railway construction clearance. The outer sling 4 of the basket and the bottom crossbeam 6 of the basket form a reliable suspended working platform, while the outer guide beam 5 provides a dedicated track and support for the step-by-step and precise forward movement of the side formwork 11. Most importantly, the fully enclosed protective component 7, connected to the bottom of the bottom crossbeam 6 of the basket and the outside of the side formwork 11, together with the template that has undergone multiple sealing treatments, forms a rigid enclosed space without dead angles, physically completely blocking any possibility of tools, materials, or concrete slurry falling or leaking during construction, providing a fundamental guarantee for the safe operation of the railway line below.

[0027] Specifically, the fully enclosed protective component 7 covers the railway track 14 of the operating line below, achieving physical isolation between the construction area and the operating line.

[0028] See Figure 4 As shown in the figure, an embodiment of the present invention provides a method for the closure construction of a continuous beam rotating near an operational railway line using a suspended frame, comprising the following steps: S1: After the construction of the T-shaped cantilever section is completed and before the rotation, the existing hanging basket 100 and formwork 200 on the mid-span side are modified to form a suspended frame, and the modified suspended frame is anchored to the beam on the mid-span side of the T-shaped structure; S2: The T-shaped structure with the suspended frame anchored is rotated into position; S3: After the rotation is in place, within the time limit of the railway closure, the partial anchoring of the suspended frame is released, and it is driven to travel along the track laid on the bridge deck to the design position of the closure section and re-anchored; S4: Within the fully enclosed protective component 7 set on the suspended frame, the stiffening frame of the closure section is locked, the steel bars are tied, and the concrete is poured; S5: After the construction of the closure section is completed, within the time limit of the railway closure, the suspended frame is moved back to a safe area and dismantled.

[0029] In this embodiment, by directly utilizing the existing hanging basket 100 and template 200 on site and modifying them into a dedicated gantry, the cost of purchasing new materials and leasing equipment was significantly reduced, demonstrating remarkable economic efficiency. The modified gantry was pre-anchored and rotated along with the T-structure, allowing the main installation work to be completed without railway interference, greatly improving construction efficiency and reserving time windows for critical steps. After rotation, the gantry was driven to precisely move and position itself along the bridge track within a short railway closure point, strictly limiting high-risk operations to a controllable time period and minimizing the impact on the operation of the operating line below, demonstrating strong adaptability. The entire closure section operation was carried out within the fully enclosed protective component 7 carried by the gantry. This structure fundamentally eliminates the risk of falling debris and concrete leakage during construction, providing absolutely reliable physical isolation protection for railway traffic safety. Finally, the gantry was also moved back and dismantled within the closure point, forming a closed-loop safety management system from positioning and construction to withdrawal, systematically solving the core contradiction of balancing safety, cost, and efficiency in closure construction near operating lines.

[0030] Specifically, compared with the scaffolding method, the hanging scaffolding method uses existing hanging baskets and T-shaped formwork for modification, which can save a lot of pipe fitting rentals and has significant economic benefits.

[0031] Scaffolding Method: Construction of the protective scaffolding columns falls under Category B and C construction adjacent to operating lines, allowing only brief intervals between train passages. Installation of the transverse distribution beams and top steel plates is Category III construction, requiring a line closure application. Construction must be carried out within the closure period, necessitating multiple closure applications. The distance between the scaffolding and the railway clearance is limited. Prolonged construction on both sides of operating lines carries high safety risks. Due to the proximity to operating lines, scaffolding erection takes a long time (30 days for scaffolding erection, 15 days for the closure section, and 30 days for scaffolding dismantling), totaling 75 days.

[0032] Hanging Frame Method: Before rotation, the existing hanging basket is modified, which is relatively simple to operate. The hanging frame is anchored to the side of the T-structure's middle span. After rotation, the hanging frame is moved forward, which is a Class III construction method. A closure period is requested for placement, and the procedure is relatively simple. The longer distance from the railway clearance meets the construction requirements. Hanging basket modification takes 7 days, and the closure section construction takes 15 days. The construction time for the closure section is the same as the canopy method.

[0033] In step S1, the modification of the existing hanging basket 100 and template 200 on the mid-span side includes: removing the diamond truss 9 of the hanging basket 100 and directly installing the upper crossbeam 3 of the hanging basket 100 onto the hanging basket track 2 to lower the center of gravity of the hanging basket.

[0034] In this embodiment, by removing the tall rhomboid truss 9 from the existing hanging basket 100 and directly installing the reinforced upper crossbeam 3 of the hanger onto the top of the hanging basket track 2 laid on the pad beam 1, the hanger structure is fundamentally simplified and the center of gravity is significantly lowered. This simplifies the force transmission path of the entire hanger from the traditional beam-truss-to-crossbeam to a more efficient beam-to-track-to-crossbeam, significantly improving the overall rigidity and stability of the structure. The low center of gravity design ensures enhanced anti-overturning capability of the hanger during subsequent travel and operation, effectively eliminating the risk of equipment encroaching on railway construction clearances due to swaying or wind loads. At the same time, this modification makes full use of existing core components, greatly reducing the processing and input of additional materials, achieving significant economic benefits and ease of construction.

[0035] Specifically, such as Figure 5 and Figure 6 As shown, the existing hanging basket 100 is a conventional diamond-shaped hanging basket used during the construction of the T-shaped cantilever section. Its main load-bearing structure is a diamond truss 9. The upper beam 3 of the hanger was originally a component connecting the hanging basket 100 to the front end of the diamond truss 9. The hanging basket track 2 was originally laid on the bridge deck for the hanging basket 100 to move. The core of this modification step is to remove the upper beam 3 of the hanger from the diamond truss 9 and directly install and anchor it to the hanging basket track 2, thereby eliminating the original truss structure of the hanging basket 100 and forming the core load-bearing frame of the low center of gravity hanger.

[0036] In step S1, during the modification and anchoring of the hanger, counterweights 13 are set on designated sections on both sides of the T-structure to ensure the torque balance of the T-structure.

[0037] In this embodiment, by precisely setting counterweights on designated segments (typically blocks 4-5) of the cantilevered sections on both sides of the T-structure, active control of the overall moment balance of the T-structure is achieved. Directly addressing the unbalanced bending moment introduced by the installation and load of the single-sided hanger, the counterweights are calculated and applied to the corresponding positions, ensuring the structural stability and safety of the T-structure before rotation and in subsequent processes. This effectively prevents additional internal forces, torsional deformation, or elevation changes that may occur in the beam due to uneven stress, laying the foundation for subsequent rotation weighing, smooth rotation, and precise alignment of the closure section.

[0038] The movement is driven by jacking; the movement process is carried out in steps, including first releasing the anchorage of the bottom basket 10 of the scaffold, lowering the sling to detach the formwork 200 from the beam, and driving the bottom basket 10 forward; then releasing and anchoring the side formwork 11 in steps, and alternately pulling the side formwork 11 and the outer guide beam 5 forward.

[0039] In this embodiment, the bottom basket 10, composed of the bottom crossbeam 6, is first driven forward to ensure a smooth transition of the main load. Then, by alternately pulling the side formwork 11 and the outer guide beam 5, the side system is gradually delivered to the design position using the relative motion between them. This fully utilizes the low center of gravity sliding stability of the upper crossbeam 3 on the basket track 2, and precisely controls the separation and closure of the formwork 200 from the existing beam by extending and retracting the outer suspension straps 4 of the basket. This step-by-step implementation not only breaks down the complex overall movement into controllable, simple steps, but also significantly reduces the instantaneous load impact on the basket track 2 and the pad beam 1.

[0040] Specifically, the gantry's traveling track utilizes the existing track of the hanging basket 100. A steel plate is welded to a sliding bollard below the upper crossbeam 3 of the gantry to reduce traveling resistance. Before traveling, the beam surface anchorage is released. The lower crossbeam transfers the load of the bottom formwork and side formwork 11 to the upper crossbeam 3 of the gantry via four lifting straps. The outer edges of the four hanging basket lifting straps 4 are lowered by 15cm to detach the side formwork 11 and bottom formwork from the beam. Precision-rolled threaded steel bars, jacks, and a hydraulic system are installed. The gantry is pushed forward using jacks at a traveling speed of 0.1 m / min. During travel, symmetrical synchronization should be maintained to avoid uneven loading that could cause track deformation or structural instability.

[0041] The template 200 is a general system term, specifically including a bottom template for forming the bottom structure of the closure section and side templates 11 for forming the web and flange structure of the closure section. The side templates 11 are connected to the outer guide beam 5 via a support structure on their backs, with the outer guide beam 5 bearing their weight and providing guidance for movement. In step S3, "step-by-step release and anchoring of the side templates 11" specifically refers to performing a cyclical "anchoring-release-traction-re-anchoring" operation, independent of the bottom basket 10, on this part of the side forming template system connected to the outer guide beam 5, to achieve precise, step-by-step forward movement along the outer guide beam 5.

[0042] like Figure 6 and Figure 7As shown, a synchronous weight-replacement method is used during concrete pouring to maintain the force balance of the cantilever on both sides of the closure joint.

[0043] In this embodiment, the vertical displacement and relative rotation caused by changes in construction load at the closure joint were suppressed by the synchronous weight replacement method, thus ensuring the stability of the position of the pre-installed stiffening frame and prestressed duct.

[0044] like Figure 3 As shown, synchronous weight replacement is achieved through a counterweight water tank 12 set at the cantilever end of the T-structure. The weight replacement is determined based on the weight of the concrete in the closure section and the construction load, and the water stored in the water tank is discharged synchronously in proportion during the concrete pouring process.

[0045] In this embodiment, during the pouring of the closure section concrete through the formwork 200, water is simultaneously added to the counterweight tank 12 according to the pre-calculated weight and the pouring schedule. This process essentially transfers the additional concrete load applied to the bottom beam 6 of the hanging basket to the counterweight of the T-structure in real time and in reverse, thereby actively maintaining the overall moment balance centered on the pier. This structured active control mechanism effectively suppresses the deflection and rotation of the beam that may occur due to load asymmetry, ensures the stability of the closure gap after the stiffening frame is locked, provides a uniform, strain-free setting environment for the closure section concrete, guarantees the final bridge alignment and structural quality, and improves the safety of the construction process.

[0046] Specifically, the closure of the mid-span will cause an asymmetry in the load between the side and mid-spans, in which case the replacement of the load with a heavier one should be considered.

[0047] Replacement weight (G) = Increased weight of the suspended section caused by the closure section concrete + temporary construction load.

[0048] For example, 12 counterweight water tanks are arranged on both sides of the cantilever end of the T-structure centerline. The center of the water tank in the middle span is 17m away from the centerline of block #0. Water tanks are arranged at segments 4-5 outside the safety clearance of the operating line on the middle span side of the T-structure. The center of the water tank on the side span is 24.5m away from the centerline of block #0. The center of the water tank on the side span side of the T-structure is 3m away from the end of the side span. The weight of the closure section is 50.65t, and the counterweight of the side span is 1 / 2 of the weight of the closure section, with a counterweight weight of 25.34t. The water tank volume is 25.34m³. When pouring concrete, 2.6m³ of water needs to be released from the water tank for every 1m³ of concrete poured. The water tank should have a graduated scale or marked lines to control the amount of water released. The weight of the counterweight on the middle span side is calculated based on the moment balance and the position of the counterweight.

[0049]

[0050] Side counterweights during closure:

[0051] This formula is a variation of the moment balance equation. During the construction of T-shaped structure rotation, scaffolding forward movement, or closure section, in order to ensure the force balance on both sides of the pier, it is necessary to set counterweights at designated locations (side span or middle span) to counteract the unbalanced moments caused by equipment movement (such as hanging baskets or scaffolding) or load changes (such as concrete pouring). Given the counterweights of the side spans and the positions and weights of the equipment on both sides, how much counterweight needs to be placed at a specific lever arm position in the middle span to achieve moment balance for the entire bridge.

[0052] in, Side counterweight weight; : The distance of the lever arm from the center of the side counterweight to the center line of block #0; Weight of the side hanging basket (and formwork, etc.) on the side span; : The distance of the lever arm from the center of gravity of the side-mounted basket to the center line of block #0; : Weight of the side counterweight in the middle span; : The distance of the lever arm from the center of the counterweight on the middle span side to the center line of block #0; Weight of the side scaffolding (including formwork, protection, construction load, etc.) in the middle span; : The distance of the lever arm from the center of gravity of the side hanger in the middle span to the center line of block #0.

[0053] After the closure section's weight replacement stabilizes, and the linearity test confirms that the error does not exceed design and specification requirements, the stiffening frame is locked. All weight replacements utilize water tanks, each marked with a metering indicator.

[0054] After installing the template 200, multiple sealant applications are made to the template joints using expanding foam, double-sided tape, and transparent tape.

[0055] In this embodiment, expanding foam is first used to fill the main gaps, providing initial sealing and cushioning. Then, double-sided tape is applied to the surface to enhance adhesion and airtightness. Finally, transparent tape is used to cover the surface, forming a smooth and continuous final line of defense. Through the combined effect of multiple seals and the fully enclosed protective component 7 at the bottom of the hanger and the protective netting on the sides, all possible paths for concrete slurry leakage are completely blocked, ensuring that during the pouring and vibration of the closure section, cement slurry will absolutely not leak or splash from the formwork system supported by the bottom crossbeam 6 and the outer guide beam 5. This fundamentally eliminates the possibility of concrete contaminating the railway tracks and equipment below, greatly enhancing the reliability and integrity of the entire fully enclosed protective component 7.

[0056] The stiffening frame is welded and locked during periods of lower daily temperature; after the stiffening frame is installed, some of the longitudinal prestressed steel strands are pre-tensioned; the concrete used is early-strength micro-expansion concrete, which is one grade higher than that used for the beam.

[0057] In this embodiment, firstly, the locking stiffening frame is welded during a period of low and stable daily temperature. This fixes the closure opening width at its relatively maximum, allowing the thermal expansion of the beam to pre-generate compressive stress within the frame as the temperature rises, thus offsetting the tensile stress generated by concrete shrinkage. Secondly, immediately after the stiffening frame is installed, some longitudinal prestressed steel strands are pre-tensioned. This proactively applies a prestress opposite to the expected temperature shrinkage stress to the entire closure segment structure, establishing a crack-resistant barrier. Finally, early-strength micro-expansion concrete is used. Its early-strength characteristics shorten the waiting time before bearing load and accelerate the construction pace; its micro-expansion characteristics generate moderate expansion compressive stress during hardening, further compensating for the concrete's own shrinkage. These three factors work synergistically within the closure segment formwork system supported by the hanging basket bottom beam 6 and the outer guide beam 5, creating a complete process from the initial setting to final strength formation for the newly poured concrete. This fundamentally ensures the structural integrity of the closure segment, achieving a high-quality closure without cracks.

[0058] After the concrete of the closure section reaches its strength, the prestressed steel strands are tensioned in sequence to complete the system conversion. The sequence is as follows: first, pre-tensioning is performed on some of the closure strands, then the stiffening skeleton is released, and finally all the remaining prestressed steel strands are tensioned. After tensioning is completed, grouting of the ducts is carried out within the specified time.

[0059] In this embodiment, pre-tensioning is first applied to a portion of the closure strands. This allows some permanent prestress to be introduced into the closure segment and adjacent beams, enabling them to share the load while still being rigidly connected by the stiffening frame. Subsequently, the stiffening frame is released. The key to this step is that the concrete in the closure segment already possesses sufficient strength, and the pre-tensioning force provides a certain degree of active constraint, thus safely achieving the transition from a temporarily rigidly locked structural system to a permanently prestressed load-bearing system, avoiding stress redistribution impact caused by sudden unloading. Finally, all remaining prestressed steel strands are tensioned, establishing a complete design prestressed system under ideal conditions without temporary constraint interference, ensuring that the internal force state and alignment of the completed bridge fully meet design requirements. Grouting of the ducts within a specified time after the entire process is completed provides permanent protection for the tensioned steel strands, preventing corrosion and ensuring the long-term reliability of prestress transfer. Ensuring the safety of the structure during the transition process and the final forming quality is a crucial step in achieving a high-quality closure.

[0060] Specifically, the closure method of the hanging frame is as follows: like Figure 5As shown, the left pier has a pre-reserved hole for the fixed hanger in block 8. The middle sling of the lower crossbeam in front of the hanging basket is removed, and the outermost sling is retained. After the construction of block 8 is completed, the hanging baskets on both sides are moved back one segment and anchored to ensure the torque balance of the T-structure. The unbalanced weight on both sides does not exceed 8 tons.

[0061] After the construction of block 8 on the right pier is completed, the hanging formwork on the mid-span side will be removed in situ, and the hanging formwork on the side span will be moved back one segment for anchoring. Counterweights will be installed on the mid-span side, positioned on sections 4-5, while ensuring the T-structure moment balance, with the unbalanced weight on both sides not exceeding 8 tons.

[0062] like Figure 6 As shown, the front and rear lower crossbeams of the hanging basket on the left pier mid-span side, as well as the side formwork 11 and the outer guide beam 5, are anchored to the beam surface using high-strength threaded steel. After the anchoring is completed, the upper crossbeam of the hanging basket hanger and the diamond truss of the hanging basket are removed, while ensuring the T-structure moment balance and the unbalanced weight on both sides does not exceed 8 tons.

[0063] like Figure 7 As shown, on the left pier mid-span side, the upper crossbeam of the hanging basket and the outermost lifting strap are installed using the upper crossbeam of the hanging basket, while ensuring the moment balance of the T-structure, with the unbalanced weight on both sides not exceeding 8 tons. A truck crane is used to lift the precast concrete block counterweight, which is located on sections 4-5 on the left pier mid-span side. The weight of the counterweight is calculated based on the moment balance.

[0064] like Figure 8 As shown, after the hanger is installed on the left pier mid-span side, it is moved forward to the beam end and the side formwork 11, bottom basket 10, and guide beam are anchored to the beam surface using precision-rolled threaded steel. At the same time, the outer guide beam 5 is retracted to prevent collision, while ensuring the T-structure moment balance, with the unbalanced weight on both sides not exceeding 8 tons. A weighing test and counterweight are performed before rotation.

[0065] like Figure 9 As shown, after the structure is rotated into place, the closure time is requested. The anchorages of the bottom basket 10 and the outer guide beam 5 with precision-rolled threaded steel are released, while the anchorages of the side formwork 11 remain. The bottom basket 10 is supported by the outermost sling, which is then lowered. Then, jacks are used to move the bottom basket 10 forward, and a winch is used to pull the outer guide beam 5 forward. As the gantry moves forward, the corresponding counterweight weight is calculated based on the torque balance. A truck crane is used to lift the precast concrete block counterweight, which is positioned on the left side of the pier's mid-span, on sections 4-5. As the gantry moves forward, the counterweight is reduced according to the calculations.

[0066] like Figure 10 As shown, the side formwork 11 is released from anchorage, and the guide beam bears the weight of the formwork. Then, a winch is used to pull the side formwork 11 forward, and a hand-operated hoist is used to tighten the rear end of the guide beam.

[0067] like Figure 11 As shown, the side formwork 11 is anchored to the beam surface again, and then the guide beam is pulled forward.

[0068] like Figure 12As shown, the side formwork 11 is released from anchorage, the guide beam bears the weight of the formwork, and then a winch is used to pull the side formwork 11 forward, while a hand chain hoist tightens the rear end of the guide beam.

[0069] like Figure 13 As shown, the guide beam with side formwork 11 moves forward to the design position, then the steel reinforcement of the mid-span closure section is tied, the concrete of the closure section is poured, and the prestressed tendons of the mid-span closure section are tensioned.

[0070] like Figure 14 As shown, after the prestressed tendons of the mid-span closure section are tensioned, a closure period is applied for. After the bottom basket of the hanging frame is lowered to the outside of the safety boundary, it is dismantled. Then the side span hanging basket is moved forward to the side span closure section.

[0071] like Figure 15 As shown, concrete was poured for the side span closure section, and counterweights were added to the middle span.

[0072] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A suspension bracket closure structure for a line adjacent to an operational line, characterized in that, Includes pad beam (1), hanging basket track (2), upper crossbeam of the hanger (3), outer hanging basket sling (4), outer guide beam (5), bottom crossbeam of the hanging basket (6) and fully enclosed protective components (7); The pad beam (1) is laid and fixed on the bridge surface of the bridge body (8), the hanging basket track (2) is fixed to the top of the pad beam (1), and the hanging basket track (2) reuses the original hanging basket travel track; The upper beam (3) of the hanger is supported on the hanging basket track (2); The outer suspension strap (4) of the hanging basket is vertically inserted and connected to the upper crossbeam (3) of the hanging frame, and the bottom crossbeam (6) of the hanging basket is horizontally connected to the bottom end of the outer suspension strap (4); The outer guide beam (5) is fixedly connected to the bottom of the hanging basket track (2) and adapted to the side mold (11) for pulling the side mold (11) forward step by step; The fully enclosed protective component (7) is connected to the bottom of the hanging basket bottom beam (6) and the outside of the side mold (11) to form a protective space without dead angles.

2. A method for constructing a gantry-type closure structure near an operational railway line, using the gantry-type closure structure as described in claim 1, characterized in that... Includes the following steps: S1: After the construction of the T-shaped cantilever section is completed and before the rotation, the existing hanging basket (100) and formwork (200) on the middle span side are modified to form a hanging frame, and the modified hanging frame is anchored to the beam on the middle span side of the T-shaped structure. S2: Rotate the entire T-structure of the anchor hanger into position; S3: After the bridge is rotated into place, within the time limit of the railway closure point, release part of the anchorage of the gantry, drive it along the track laid on the bridge deck to the design position of the closure section and re-anchor it; S4: Within the fully enclosed protective assembly (7) installed on the hanger, the locking of the stiffening frame of the closure section, the binding of the reinforcing bars and the pouring of concrete are completed; S5: After the closure section is completed, the gantry will be moved back to a safe area and dismantled within the time limit for railway closure.

3. The construction method as described in claim 2, characterized in that, In step S1, the modification using the existing hanging basket (100) and template (200) on the mid-span side includes: removing the diamond truss (9) on the hanging basket (100) and installing the upper crossbeam (3) of the hanging basket (100) on the hanging basket track (2) to lower the center of gravity of the hanging basket.

4. The construction method as described in claim 2, characterized in that, In step S1, during the modification and anchoring of the hanger, counterweights (13) are set on designated sections on both sides of the T-structure to ensure the torque balance of the T-structure.

5. The construction method as described in claim 2, characterized in that, In step S3, the driving of its movement is carried out by jacking; the movement process is carried out in steps, including first releasing the anchor of the bottom basket (10) of the gantry, lowering the sling to make the template (200) detach from the beam, and driving the bottom basket (10) to move forward; then releasing and anchoring the side formwork (11) in steps, and alternately pulling the side formwork (11) and the outer guide beam (5) forward.

6. The construction method as described in claim 2, characterized in that, In step S4, a synchronous weight replacement method is used during concrete pouring to maintain the force balance of the cantilever on both sides of the closure joint.

7. The construction method as described in claim 6, characterized in that, The synchronous weight replacement is achieved by setting a counterweight water tank (12) at the cantilever end of the T-structure. The weight replacement is determined based on the weight of the concrete in the closure section and the construction load, and the water stored in the water tank is discharged synchronously in proportion during the concrete pouring process.

8. The construction method as described in claim 2, characterized in that, In step S4, after installing the template (200), multiple seals are applied to the template joints using expanding foam, double-sided tape, and transparent tape.

9. The construction method as described in claim 2, characterized in that, In step S4, the stiffening frame is welded and locked during periods of low daily temperature; after the stiffening frame is installed, some of the longitudinal prestressed steel strands are pre-tensioned; the concrete used is early-strength micro-expansion concrete, which is one grade higher than that used in the beam.

10. The construction method as described in claim 2, characterized in that, In step S4, after the concrete of the closure section reaches its strength, the prestressed steel strands are tensioned in sequence to complete the system conversion. The sequence is as follows: first, some of the closure strands are pre-tensioned, then the stiffening frame is released, and finally all the remaining prestressed steel strands are tensioned. After tensioning is completed, the duct is grouted within the specified time.

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