Construction method of one-connection prefabricated bridge superstructure under space limited working condition

Abstract

This invention relates to a construction method for the superstructure of a precast bridge under space-constrained conditions. The superstructure of a precast bridge is divided longitudinally into a standard span and a sliding span, which are arranged alternately in sequence. During the installation of the sliding span, one crane is positioned under the bridge projection plane within the span, and another crane is positioned under the bridge projection plane outside the span. These two cranes are used to install the smaller box girders within the sliding span, except for one central box girder. Simultaneously, the central box girder is hoisted and placed on one side of the side box girder. During the installation of the standard span, one crane is positioned under the bridge projection plane of the already installed sliding span, and the other crane is positioned under the bridge projection plane of the span following the standard span. These two cranes are used to install and position each small box girder of the standard span. The central box girder of the sliding span is moved transversely and lowered by hoisting. The advantages of this invention are that it ensures construction efficiency while being economical and reliable.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a construction method for a precast bridge superstructure under space-constrained conditions. Background Technology

[0002] The main lifting equipment for conventional bridge beams includes truck cranes, crawler cranes, floating cranes (suitable for operation on rivers), bridge cranes, and gantry cranes.

[0003] Currently, bridge erecting machines are generally used to address the limited space for hoisting operations beneath bridges. However, using bridge erecting machines also presents several limitations: 1. They must be installed span by span in the direction of increasing or decreasing bridge station number to meet the need for feeding the erecting machine with beams; 2. When vehicles transporting beams cannot directly reach the bridge, a beam lifting station must be considered to vertically transport the beams to the bridge deck; 3. Different bridge erecting machines have different structures and can adapt to different bridge design conditions. Bridge erecting machines generally have the following limitations: longitudinal slope (generally less than 5%), cross slope (generally less than 4%), single span (generally 30-50m), and design radius of curvature (generally greater than 150m). When any of these limitations cannot be met, bridge erecting machines cannot be used for beam erection.

[0004] Truck cranes and crawler cranes generally do not require installation span by span or additional beam lifting equipment, making them widely adaptable to various bridge design conditions. However, they have high requirements for working space, generally requiring at least 10 meters of working space beyond the bridge's projection plane.

[0005] Gantry cranes generally do not have high requirements for the size of the working space, but they have high requirements for the track foundation. They usually require special strip foundations for construction, which can be costly for short-distance bridge construction. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a construction method for the superstructure of a precast bridge under space-constrained conditions. This method employs a dual-machine lifting system to install all beams except for one central beam within the bridge's projection plane. The final central beam is then installed to its designed position using a beam lateral movement and lowering device. This method solves the problem of difficult construction of a precast bridge due to limited external construction space.

[0007] The objective of this invention is achieved through the following technical solutions:

[0008] A construction method for the superstructure of a precast bridge under space-constrained conditions, used to install multiple small box girders on the cap beam of a precast bridge, wherein the small box girders are divided into middle box girders and side box girders according to their position, characterized in that: the construction method includes:

[0009] The superstructure of the precast bridge is divided into standard spans and sliding spans along the bridge direction, and the standard spans and the sliding spans are arranged alternately in sequence.

[0010] During the installation of the sliding span, one crane is arranged under the bridge projection plane inside the span, and another crane is arranged under the bridge projection plane outside the span. The two cranes are used to complete the installation of the beams of the small box girders in the sliding span, except for one medium box girder; at the same time, the medium box girder is hoisted and placed on the side box girder on one side.

[0011] During the installation of the standard span, one crane station is located below the bridge projection plane of the already installed sliding span, and the other crane station is located below the bridge projection plane of the next span after the standard span. The two cranes are used to complete the installation and positioning of each small box girder of the standard span.

[0012] The middle box girder of the sliding span is moved laterally and then lowered into place by hoisting.

[0013] During the installation of the sliding span, the main boom of the crane located under the bridge projection plane inside the span extends through the gap formed between the uninstalled middle box girder and the cap beam, and works in conjunction with the crane outside the span to lift the middle box girder.

[0014] During the installation of the standard span, the main boom of the crane, which is positioned under the bridge projection plane of the already installed sliding span, extends through the gap formed between the uninstalled middle box girder and the cap beam, and works in conjunction with the crane located under the bridge projection plane of the next span to lift each small box girder within the standard span.

[0015] Before sliding down the box girder of the sliding span, the installation of each standard span and the sliding span is repeated sequentially along the bridge direction.

[0016] The advantages of this invention are:

[0017] 1) Solving the problem of hoisting bridge beams with large longitudinal slopes and curvatures:

[0018] In some strictly space-constrained design conditions (e.g., longitudinal slope greater than or equal to 5%, transverse slope greater than or equal to 4%, radius of curvature less than or equal to 150m), conventional bridge erecting machines and gantry cranes are not easy to implement; the method provided by this invention can solve the problem of bridges with large longitudinal slopes or large curvatures.

[0019] 2) Economical and cost-effective:

[0020] Under such complex boundary conditions, other hoisting methods often require additional measures to achieve the desired implementation. For each kilometer of bridge beam installation, this invention is expected to save 500,000 to 2 million yuan compared to other hoisting methods.

[0021] 3) High overall construction efficiency:

[0022] After the construction of the superstructure of the bridge is completed, the middle beam on the sliding span is positioned by the beam lateral movement and lowering device. This step does not occupy the working surface for hoisting other beams, and the beam of the sliding span can be laterally moved and lowered into position at the same time as the beams of other spans are installed, resulting in high overall construction efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the span arrangement of the present invention;

[0024] Figure 2 This is a schematic diagram of the lifting plan and elevation of the sliding span in this invention;

[0025] Figure 3 This is a schematic diagram of the longitudinal section of the sliding span hoisting in this invention;

[0026] Figure 4 This is a schematic diagram of the hoisting plan and elevation of the standard span in this invention;

[0027] Figure 5 The construction steps for lowering the box girder after lateral sliding according to the present invention are as follows. Figure I ;

[0028] Figure 6 The construction steps for lowering the box girder after lateral sliding according to the present invention are as follows. Figure II ;

[0029] Figure 7 The construction steps for lowering the box girder after lateral sliding according to the present invention are as follows. Figure III ;

[0030] Figure 8 The construction steps for lowering the box girder after lateral sliding according to the present invention are as follows. Figure IV ;

[0031] Figure 9 The construction steps for lowering the box girder after lateral sliding according to the present invention are as follows. Figure V ;

[0032] Figure 10 The construction steps for lowering the box girder after lateral sliding according to the present invention are as follows. Figure VI ;

[0033] Figure 11 This is a schematic diagram of the reaction frame in this invention;

[0034] Figure 12 This is a schematic diagram of the structure of the sliding shoe and guide rail in this invention;

[0035] Figure 13 This is a schematic diagram of the beam-dropping frame in this invention;

[0036] Figure 14 This is a schematic diagram of the balance beam in this invention. Detailed Implementation

[0037] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art:

[0038] like Figure 1-14 As shown in the figure, markings 1-29 represent: sliding span 1, standard span 2, first crane 3, second crane 4, side box girder 5, middle box girder 6, cap beam 7, slip shoe 8, guide rail 9, steel section 10, round steel pipe 11, supporting steel section 12, beam lowering frame 13, balance beam 14, tapered frame 15, sleeper 16, shackle 17, vertical plate 18, corner plate 19, MGE plate 20, transverse bridge adjustment jack 21, longitudinal bridge adjustment jack 22, H-beam crossbeam 23, upper flange connecting plate 24, distribution beam 25, stiffening rib 26, lifting tool ear plate 27, channel steel 28, stiffening plate 29.

[0039] Example: Figures 1 to 14 As shown in this embodiment, the construction method for the superstructure of a precast bridge under space-constrained conditions involves hoisting and positioning the precast middle box girder 6 and side box girder 5 onto the already erected cap beam 7. Figure 1 As shown, this embodiment uses three small box girders as an example, including one central box girder 6 that needs to be erected on the cap beam 7, and two side box girders 5 located on either side of it. During construction, this embodiment mainly addresses the construction problem of this precast bridge under conditions of limited external space.

[0040] Specifically, the construction method in this embodiment includes the following steps:

[0041] S1, such as Figure 1 As shown, based on the environmental conditions at the hoisting site, the precast bridge section is divided into sliding span 1 and standard span 2 along the longitudinal direction, with the two alternating in sequence. Three small box girders are erected in both sliding span 1 and standard span 2.

[0042] S2, such as Figure 2 and Figure 3 As shown, during the installation of sliding span 1, the first crane station 3 is located below the bridge projection plane inside the span of sliding span 1, and the second crane station 4 is located below the bridge projection plane outside the span. The installation of the side box beams 5, except for the middle box beam 6, is completed in sequence.

[0043] By simulating the hoisting conditions, special attention should be paid to analyzing whether the main boom of the first crane 3 will be affected by the already installed beam (side box girder 5) during the hoisting process. The stopping position of the first crane 3, located within the span, should be determined in the working condition diagram, and the crane should be guided on-site to strictly follow the stopping position in the working condition simulation. The main boom of the first crane 3 extends through the gap formed between the uninstalled middle box girder 6 and the cap beam 7, and works with the second crane 4 outside the span to hoist the last middle box girder 6 onto the side box girder 5 for temporary placement.

[0044] S3, such as Figure 4 As shown, during the installation of standard span 2, one crane, typically the first crane 3, is positioned below the bridge projection plane of the sliding span 1, which has already been installed in the previous step. The main boom of the first crane 3 extends through the gap in the position of the middle box girder 6, which has not yet been installed in the sliding span 1. The other crane, typically the second crane 4, is positioned below the bridge projection plane of the span following the standard span. The two cranes install each beam of standard span 2 in a certain order, including the installation of the middle box girder and the side box girder on standard span 2.

[0045] Through steps S2 and S3 and in combination Figures 2 to 4 As shown in the figure, the construction range of the first crane 3 and the second crane 4 in this embodiment is indicated by their outer circular outline. It can be seen that the construction influence range of the first crane 3 and the second crane 4 in this embodiment is mainly below the bridge projection plane, with only the parts on both sides of the transverse bridge slightly exceeding the bridge projection plane. Therefore, the construction of the superstructure of a precast bridge under space-constrained conditions is realized.

[0046] S4. Repeat steps S2 and S3 to install each sliding span 1 and standard span 2 in sequence along the bridge direction.

[0047] S5. Slide each middle box girder 6 on each sliding span 1 in the transverse direction and place it at the designed position between the side box girders 5 on both sides.

[0048] like Figures 5 to 14 As shown in the figure, this embodiment provides a device for the lateral sliding and lowering of the beam of the middle box girder 6. However, in actual use, various technical means can also be used to achieve this construction.

[0049] Specifically, in this embodiment, the device for laterally sliding and lowering the beam is used to laterally slide the middle box girder 6 and lower it between the side box girder 5 on both sides. The middle box girder 6 and the side box girder 5 on both sides are three small box girders supported on the cap beam 7. These three small box girders are arranged side by side. Due to the limitation of construction space, the middle box girder 6 is temporarily stacked on one side of the side box girder 5. At this time, it is necessary to move the middle box girder 6 between the side box girder 5 on both sides.

[0050] The device will be described below in conjunction with the construction method of this embodiment, as follows:

[0051] I. Installation and reinforcement of sliding equipment:

[0052] 1) Measure and confirm the installation position of guide rail 9. Guide rail 9 is the track that provides the middle box girder 6 for lateral sliding and is part of the lateral sliding system. Guide rail 9 is laid along the lateral sliding direction of the middle box girder 6, and its two ends are laid on the side box girders 5 on both sides.

[0053] 2) Use supporting steel 12 to support and reinforce the cantilever ends of the side box girder 5. The supporting steel 12 can be H-beams, specifically arranged below the cantilever ends on both sides of the side box girder 5 to effectively support the cantilever ends of the side box girder 5 from below, preventing damage during the movement of the middle box girder 6.

[0054] 3) Using round steel pipes 11 and structural steel 10, a reinforcing frame is erected below the designed placement position of the guide rail 9. This reinforcing frame is located between the side box beams 5 on both sides, i.e., the position where the middle box beam 6 is to be lowered. This reinforcing frame is part of the lateral sliding system and is used to ensure that the guide rail 9 as a whole can be stably supported, thereby ensuring the safety of the middle box beam 6 during the lateral sliding process.

[0055] 4) The guide rail 9 is installed horizontally and fixed with the mounting plate.

[0056] 5) Thin jacks are installed at the bottom of the middle box girder 6 to lift it up. Then, the sliding shoe 8 and reaction frame are installed onto the guide rail 9. The sliding shoe 8 and reaction frame are also part of the lateral sliding system. The sliding shoe 8 is installed at the bottom of the middle box girder 6 and further supported on the guide rail 9, with a sliding fit between the sliding shoe 8 and the guide rail 9. Figure 7 As shown, the reaction frame consists of a vertical plate 18 and a corner plate 19. The corner plate 19 is installed on one side of the vertical plate 18, and the other side of the vertical plate 18 is also provided with a plate for fixed connection with the guide rail 9. The function of the reaction frame is to provide reaction force for the lateral movement of the middle box girder 6.

[0057] 6) Install steel strands and anchors between the reaction frame and the slipper 8.

[0058] 7) Install the traction jack at the reaction frame and connect it to the hydraulic trolley via the oil circuit.

[0059] 8) Remove the original sleepers below the middle box girder 6, and use thin jacks to lower the middle box girder 6 onto the sliding shoe 8.

[0060] II. Traction and Slippage:

[0061] 1) such as Figure 2As shown, the hydraulic trolley is started, and the traction jack is controlled to pull the steel strand. Using the reaction frame as the reaction force, the middle box girder 6 slides on the guide rail 9. (As shown) Figure 8 As shown, in this embodiment, an MGE plate 20 is provided at the contact position between the bottom of the sliding shoe 8 and the guide rail 9. The MGE plate 20 is bolted to the sliding shoe 8 and has good elasticity and impact resistance. It can effectively eliminate the various hazards caused by the local high pressure caused by the unevenness of the guide rail 9, thereby ensuring the safety of the middle box girder 6 during lateral sliding.

[0062] 2) After the sliding is in place, the spatial position of the middle box girder 6 is determined, and the beam position of the middle box girder 6 is adjusted using the fine-tuning device on the sliding shoe 8. For example... Figure 8 As shown, the fine-tuning device includes a transverse bridge-direction adjusting hydraulic cap 21 and a longitudinal bridge-direction adjusting hydraulic cap 22 mounted on the sliding shoe 8. The transverse bridge-direction adjusting hydraulic cap 21 is used to adjust the position of the middle box girder 6 in the transverse direction, and the longitudinal bridge-direction adjusting hydraulic cap 22 is used to adjust the position of the middle box girder 6 in the longitudinal direction. Specifically, since the middle box girder 6 rests on a support on the sliding shoe 8, the two adjusting hydraulic caps can push the support in the transverse or longitudinal direction respectively, causing its position to move, thereby achieving fine-tuning of the position of the middle box girder 6.

[0063] III. Installation of the beam lowering frame:

[0064] 1) such as Figure 3 As shown, tapered frames 15 are installed on both sides of the beam lowering frame 13, and the tapered frames 15 on both sides are respectively installed on the side box beams 5. Figure 9 As shown, the beam drop frame 13 includes tapered frames 15 at both ends. A distribution beam 25 is provided above the tapered frame 15. Two rows of parallel H-beams 23 are provided above the distribution beams 25. The two rows of H-beams 23 are connected by upper flange connecting plates 24 to form a whole to ensure structural strength. Stiffening ribs 26 are also provided on the side ribs of the H-beams 23.

[0065] During installation, the positions of each tapered frame 15 are aligned with the lifting points of the middle box girder 6, and the double rows of H-shaped steel beams 23 at the top are parallel to the lateral movement direction of the middle box girder 6. In this embodiment, sleepers 16 are provided between the tapered frames 15 and the side box girder 5 to avoid damage to the side box girder 5.

[0066] 2) Fix the H-beam crossbeam 23 to the tapered frame 15 by spot welding.

[0067] 3) After assembling the screw and lifting device on the ground, they are hoisted and installed on the H-beam 23. The screw and lifting device can be installed using existing hoisting equipment, which is used to lift the middle box girder 6.

[0068] 4) Connect the connecting screw to the balance beam 14. (Example) Figure 10As shown, the balance beam 14 comprises a lifting lug plate 27 and channel steels 28 located on both sides thereof, i.e., the lifting lug plate 27 is clamped between the channel steels 28 on both sides, and the lifting lug plate 27 has lifting holes. Stiffening plates 29 are provided on the channel-shaped ribs of the channel steels 28 to ensure structural strength.

[0069] IV. Removal of Sliding Equipment and Reinforcement Measures:

[0070] 1) Disconnect the hydraulic trolley from the traction jack and connect the hydraulic trolley to the lifting device.

[0071] 2) Start the hydraulic trolley and lower the screw to a position close to the lifting lug of the middle box beam 6. Then, use the shackle 17 to connect the balance beam 14 to the middle box beam 6.

[0072] 3) such as Figure 4 As shown, the lifting device is used to lift the middle box girder 6 and separate it from the guide rail 9.

[0073] 4) Remove the sliding shoe 8, jack, reaction frame, guide rail 9 and reinforcement frame in sequence, that is, remove all components of the transverse sliding system.

[0074] V. Beam lowering and adjustment:

[0075] 1) Place supports and steel plates or temporary supports at the intended drop position of the middle box girder 6.

[0076] 2) such as Figure 5 As shown, the lifting device is used to slowly lower the middle box girder 6 to a position close to the temporary support behind the support.

[0077] 3) Based on the cross slope direction, control one side of the elevator to continue to slowly descend until the middle box girder 6 reaches the designed cross slope.

[0078] 4) Operate the lifting device to lower the middle box girder 6 to the required elevation position.

[0079] 5) Based on the position of the middle box girder 6, adjust the height of the temporary support and operate the lifting device to lift the middle box girder 6.

[0080] 6) Repeat steps 4) and 5) until the elevation of the middle box girder 6 after it is placed on the support or temporary support meets the design requirements.

[0081] 7) Wet joint reinforcement between box girder 6 and side box girder 5 in local welding.

[0082] VI. Lowering and Reinforcing the Beam Frame:

[0083] 1) Remove shackle 17 and disconnect the connection between beam drop frame 13 and middle box girder 6.

[0084] 2) Reverse the installation steps of the beam lowering frame 13 and dismantle the beam lowering frame 13.

[0085] 3) Remove the supporting steel 12 of the side box girder 5.

[0086] 4) Complete the construction, such as Figure 6 As shown.

[0087] Combination Figure 6 and Figure 7 As shown, in this embodiment, the main structure of the device for sliding the middle box girder 6 laterally and then lowering it is also erected within the bridge projection plane, thus realizing the overall construction of the superstructure of a precast bridge under space-constrained conditions.

[0088] Although the above embodiments have described the concept and embodiments of the present invention in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, and therefore will not be elaborated here.

Claims

1. A construction method for the superstructure of a precast bridge under space-constrained conditions, used to install multiple small box girders on the cap beam of a precast bridge, wherein the small box girders are divided into middle box girders and side box girders according to their position, characterized in that: The construction method includes: The superstructure of the precast bridge is divided into standard spans and sliding spans along the bridge direction, and the standard spans and the sliding spans are arranged alternately in sequence. During the installation of the sliding span, one crane is arranged under the bridge projection plane inside the span, and another crane is arranged under the bridge projection plane outside the span. The two cranes are used to complete the installation of the side box beams inside the sliding span, except for one central box beam. At the same time, the central box beam is hoisted and placed on one side of the side box beam. During the installation of the standard span, one crane station is located below the bridge projection plane of the already installed sliding span, and the other crane station is located below the bridge projection plane of the next span after the standard span. The two cranes are used to complete the installation and positioning of each small box girder of the standard span. The middle box girder of the sliding span is moved laterally and then lowered into place by hoisting.

2. The construction method for a precast bridge superstructure under space-constrained conditions according to claim 1, characterized in that: During the installation of the sliding span, the main boom of the crane located under the bridge projection plane inside the span extends through the gap formed between the uninstalled middle box girder and the cap beam, and works in conjunction with the crane outside the span to lift the middle box girder.

3. The construction method for a precast bridge superstructure under space-constrained conditions according to claim 1, characterized in that: During the installation of the standard span, the main boom of the crane, which is positioned under the bridge projection plane of the already installed sliding span, extends through the gap formed between the uninstalled middle box girder and the cap beam, and works in conjunction with the crane located under the bridge projection plane of the next span to lift each small box girder within the standard span.

4. The construction method for a precast bridge superstructure under space-constrained conditions according to claim 1, characterized in that: Before sliding down the box girder of the sliding span, the installation of each standard span and the sliding span is repeated sequentially along the bridge direction.

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