Erecting method of in-situ precast beam

Abstract

The invention discloses a method for erecting an in-situ precast beam, which comprises seven steps of side slope excavation and protection, lower structure construction, profile steel pedestal construction, beam sheet in-situ prefabrication, maintenance and tension, transverse movement and beam falling and subsequent construction, the precast beam is a T beam matched with a vehicle-mounted overbridge, in-situ prefabrication is carried out on a bridge site, and off-site prefabrication and beam transportation procedures are not needed; three differentiated transverse moving beam falling schemes are designed, a section steel pedestal is of a modular detachable structure and can be repeatedly used, and a leveling cushion layer is arranged on the contact face of a precast beam and a permanent support. The construction safety risk is greatly reduced, the process is simple and convenient, the construction period is short, the construction cost is saved, the construction flexibility and adaptability are high, the erection precision is high, the structural stability is good, and the construction method is suitable for various T-beam erection projects with limited sites and particularly suitable for vehicle platform bridge projects which stretch across newly-built main line expressways and are located in remote excavation sections.

Description

Technical Field

[0001] This invention belongs to the technical field of bridge construction, specifically relating to a method for erecting in-situ precast beams. Background Technology

[0002] T-beams are a common form of bridge superstructure. Currently, the mainstream construction process involves centralized prefabrication at specialized precast yards, long-distance transportation of the beams to the construction site by beam transport vehicles, and then beam erection using bridge erecting machines. This process is mature, highly standardized, and suitable for bridge projects with open sites and convenient transportation. However, it has insurmountable limitations in the construction of some special bridge locations.

[0003] For vehicular overpass projects spanning newly built main expressways and located in remote excavation sections, construction faces multiple site constraints: First, the space around the bridge site is narrow, making it impossible for the beam transport vehicle to maintain parallelism with the precast beam installation position, hindering the vehicle's movement, turning, and beam transport operations; Second, the site does not meet the requirements for the assembly, debugging, and operation space of the bridge erecting machine, making it difficult to implement the beam erection method; Third, the T-beams of this type of vehicular overpass have large spans and high self-weights. If a dual-crane method is used for erection, the lifting angle needs to be rotated and the crane position moved multiple times during construction, which not only increases construction costs but also easily leads to safety accidents such as beam overturning and crane instability due to operational errors, posing significant hidden dangers in the lifting construction.

[0004] Existing technologies for improving the erection of precast beams mainly focus on the structural optimization of beam transport vehicles and bridge erecting machines, without designing suitable construction schemes for special bridge locations with limited space. This makes it impossible to solve the problem of erecting T-beams for vehicular overpasses in remote excavation sections and across highways. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a method for erecting in-situ precast beams, which solves the technical problems of special bridge sites where traditional beam transport and bridge erection machines cannot be used due to narrow space, and the high risks associated with dual-machine platform cranes.

[0006] This invention is achieved through the following technical solution: A method for erecting in-situ precast beams includes the following steps: A. Slope excavation and protection: Use surveying instruments to mark out the bottom line of the slope excavation, excavate to 50cm below the bottom of the beam, and simultaneously complete the slope protection construction. B. Substructure construction: After accurate measurement and layout, the substructure components of the bridge, such as pile foundations, abutments, and permanent bearings, are constructed in sequence. C. Construction of steel piers: After excavating the soil 50cm below the bottom of the beam, test the bearing capacity of the foundation. If it does not meet the requirements, replace the foundation. Then, construct two precast steel piers on both sides of the abutment. The height of the steel piers is 10cm higher than the permanent supports on both sides of the abutment. D. In-situ prefabrication of beams: The prefabrication process, including steel bar binding, formwork installation, and concrete pouring, is completed on the qualified steel pedestal. E. Curing and tensioning: The precast beams are cured for seven days. After curing, the prestressing tensioning is carried out according to the design requirements. F. Lateral movement and beam lowering: After the precast beam is lifted by the lifting device, the tensioned precast beam is laterally moved to the designed installation position by the lateral movement device below the lifting device, and then the precast beam is lowered to the top of the permanent support by the lifting device. G. Subsequent construction: After all precast beams are installed, the bridge deck system and ancillary works will be constructed. The steel piers can be removed and the main roadbed will be excavated to the design elevation. Cross-operations at different levels are prohibited throughout the construction process.

[0007] Furthermore, the slope protection described in step A adopts one of the following: shotcrete and anchor, grouted rubble masonry, or steel support, which is suitable for the geological conditions of silty clay, sandstone, and mudstone interlayers at the bridge site.

[0008] Furthermore, the steel pedestal mentioned in step C is made of H-beams, I-beams, or box-shaped steel. After the steel pedestal is constructed, a load-bearing capacity test must be conducted. Only after the test is passed can the beam prefabrication work begin.

[0009] Furthermore, the lateral movement device described in step F has lateral movement, limiting and precise positioning functions, which can prevent the precast beam from moving too far laterally, and a support structure is provided to prevent the beam from overturning during the lateral movement of the precast beam. The support structure is a steel pipe support or a steel profile support.

[0010] Furthermore, in step F, the lateral movement and lowering of the beam involves installing a lateral movement device with integrated lifting function on both sides of the permanent support, and directly completing the lateral movement and lowering of the precast beam through this device.

[0011] Furthermore, in step F, the lateral beam lowering involves setting up a transverse track under the steel pedestal and anchoring it to the foundation. Hydraulic jacks are installed on both sides of the track to provide lateral movement force. After the precast beam is laterally moved, it is lowered to the sand bucket temporary supports on both sides of the permanent support, and then the beam lowering is completed through the sand bucket temporary supports.

[0012] Furthermore, in step F, the lateral beam lowering involves setting up a transverse track under the steel pedestal and anchoring it to the foundation. Hydraulic jacks are installed on both sides of the track to provide lateral movement force. At the intersection of the steel pedestal and the precast beam, additional jacks are added as a special lifting device to complete the precise lowering of the precast beam.

[0013] Furthermore, the precast beam is a T-beam, which is suitable for the superstructure of the vehicular overpass, and the precast beam is precast on-site at the bridge site, eliminating the need for off-site precasting and beam transportation processes.

[0014] Furthermore, the precast beam is erected in conjunction with the steel pedestal, lateral movement device and lifting device at the bridge site. The steel pedestal is adapted to the size and load of the precast beam, and the steel pedestal is a modular and detachable structure that can be reused.

[0015] Furthermore, a leveling pad is provided on the contact surface between the beam end of the precast beam and the permanent support. The leveling pad is made of mortar or steel plate to ensure the flatness and stability of the precast beam during erection.

[0016] The beneficial effects of this invention are: 1. Significantly reduce construction safety risks: In-situ prefabrication reduces the time and amount of work at height. The lateral movement device is equipped with limit and precise positioning functions, and an anti-overturning support structure is set up during the lateral movement process, avoiding the hoisting safety hazards caused by multiple rotations and movements of the dual-machine platform crane, thus significantly improving construction safety.

[0017] 2. Simple construction process and short construction period: The construction process of this invention is simple, without complicated large equipment assembly and debugging procedures. The precast beam can be erected within two days, which greatly shortens the construction period and improves the overall efficiency of bridge construction compared with traditional construction methods.

[0018] 3. Save on construction costs: The steel pier is a modular and detachable structure that can be reused, reducing the waste of pier materials; at the same time, it eliminates the rental, transportation and usage costs of beam transport vehicles and bridge erecting machines, and also avoids the high cost of dual-machine piers, significantly reducing the overall construction cost of the project.

[0019] 4. High flexibility and adaptability in construction: Three different transverse beam lowering implementation schemes are designed, which can be flexibly selected according to the geological conditions, load requirements and installation accuracy requirements of the bridge site. Furthermore, the slope protection and steel pedestal materials can be customized according to the site conditions, making it suitable for T-beam erection projects with various site constraints.

[0020] 5. High erection accuracy and good structural stability: The contact surface between the precast beam end and the permanent support is equipped with a leveling pad, which can effectively compensate for flatness errors. In addition, the transverse movement device has a precise positioning function, and the lifting device achieves smooth beam lowering, ensuring the accuracy of the precast beam after erection and the overall structural stability. Attached Figure Description

[0021] The present invention will now be described in further detail with reference to the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0024] Figure 3This is a schematic diagram of the structure of Embodiment 2 of the present invention. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0026] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0027] In the description of this invention, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. It should be noted that the terms "comprising," "including," or any other variations are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0028] like Figures 1-3 As shown Example 1

[0029] A method for erecting in-situ precast beams, the specific steps of which are as follows: A. Slope excavation and protection: The slope excavation line was laid out using a total station. The excavator excavated to 50cm below the bottom of the beam. The silty clay layer at the bridge site was relatively thick, so shotcrete and anchor support was used to complete the slope protection. B. Substructure construction: After accurate measurement and layout, the substructure components of the bridge, such as pile foundations, abutments, and permanent bearings, are constructed in sequence. C. Construction of steel piers: After excavating the soil 50cm below the bottom of the beam, the bearing capacity of the foundation is tested by plate load test. If it meets the requirements, no replacement is required. Two steel piers are constructed on both sides of the abutment. They are made of spliced ​​H-beams. The height of the piers is 10cm higher than that of the permanent supports. After the construction is completed, the bearing capacity is inspected and the inspection is qualified. D. In-situ prefabrication of beams: The prefabrication process, including steel bar binding, formwork installation, and concrete pouring, is completed on the qualified steel pedestal. E. Curing and tensioning: The precast beams are cured for seven days. After curing, the prestressing tensioning is carried out according to the design requirements. F. Lateral Movement and Beam Lowering: A steel rail is installed under the steel pedestal and anchored to the foundation. 200t hydraulic jacks are installed on both sides of the rail as the lateral movement power source to form a lateral movement device. H-shaped steel supports are installed on both sides of the T-beam as anti-overturning support structures. First, the jacks at the intersection are started to lift the T-beam. Then, the hydraulic jacks are started to move the T-beam laterally along the rail at a speed of 0.3m / min to the designed installation position. The T-beam is first lowered to the sand bucket temporary supports on both sides of the permanent support. Then, the sand in the sand buckets is slowly released to smoothly lower the T-beam to the top of the permanent support, completing the beam lowering. G. Subsequent construction: After the two T-beams are installed and pass inspection, the construction of bridge deck paving, crash barriers, anti-falling object nets and other bridge deck and ancillary works will be carried out; the steel pedestals will be dismantled and transferred to the next construction site for reuse; the main roadbed will be excavated to the design elevation using an excavator, and safety warning tapes will be set up during the construction process, with dedicated personnel monitoring the work and prohibiting cross-operations at different levels. Example 2

[0030] The difference between Example 2 and Example 1 lies in the lateral movement and beam lowering in step F, specifically: A lateral movement device is constructed by installing steel rails under a steel pedestal and anchoring them to the foundation, with 200t hydraulic jacks on both sides of the rails serving as the lateral movement power source. Simultaneously, a lifting device is constructed by installing jacks at the intersections of the steel pedestal and the T-beam, using a synchronous control system. H-beam supports are installed on both sides of the T-beam as anti-overturning support structures. First, the jacks at the intersections are activated to lift the T-beam, then the hydraulic jacks are activated to move the T-beam laterally along the rails at a speed of 0.3m / min to the designed installation position. Subsequently, the jacks at the intersections are activated, and the jack height is slowly lowered to precisely lower the T-beam onto the permanent support, completing the beam lowering. A 1cm thick mortar leveling pad is placed on the contact surface between the T-beam end and the permanent support to ensure flatness during erection.

[0031] The beam placement accuracy of this embodiment can reach ±2mm, which is far higher than the design requirements and is suitable for bridge projects with high installation accuracy requirements.

[0032] Example 1: Enhancing stability to accommodate heavy T-beams, solving safety and construction challenges that dual-crane platform cranes cannot handle. Core technology: Using steel rails and hydraulic jacks as the foundation for lateral movement and lifting, temporary sand bucket supports are added to achieve step-by-step beam lowering, and H-shaped steel anti-overturning supports are used to make the lateral movement and beam lowering process more stable and the load distribution better.

[0033] Addressing the pain point: In the background technology, the T-beams at special bridge locations have large spans and high self-weights. The dual-crane platform crane is prone to safety accidents due to excessive load. This embodiment significantly improves the stability of the erection of heavy-weight T-beams by using a track lateral movement and sand bucket step-by-step beam lowering design. There is no beam tilting or overturning. It specifically solves the hidden dangers of hoisting and constructing heavy-load T-beams, and eliminates the need for the high cost of investing in dual-crane platform cranes.

[0034] Suitable scenarios: Suitable for site-constrained erection projects of heavy T-beams, with basic requirements for foundation bearing capacity, and can meet the arrangement space of sand bucket temporary supports.

[0035] Example 2: Precise positioning to meet high-precision requirements, filling the technical gap in high-precision erection of special bridge sites. Core technology: Based on Example 1, a dedicated jack lifting device is added, along with a 1cm thick mortar leveling pad, which can achieve a beam dropping accuracy of ±2mm, far exceeding the conventional design requirements. The equipment operation is controlled synchronously throughout the process, resulting in more precise positioning.

[0036] Addressing the pain points: Existing technologies only optimize traditional equipment and cannot meet the high precision requirements of T-beam erection at special bridge locations. This embodiment achieves precise beam placement and flatness compensation through a dual design of a dedicated lifting device and a leveling pad, while retaining the core advantages of in-situ prefabrication and small-scale equipment construction, thus solving the problem of limited space.

[0037] Suitable scenarios: It is suitable for the erection of T-beams for vehicular overpasses with large spans and high requirements for structural splicing accuracy. It is a dedicated solution for scenarios with both limited space and high precision requirements.

[0038] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments. Any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of this invention shall fall within the scope of protection of this invention.

Claims

1. A method for erecting in-situ precast beams, characterized in that: Includes the following steps: A. Slope excavation and protection: Use surveying instruments to mark out the bottom line of the slope excavation, excavate to 50cm below the bottom of the beam, and simultaneously complete the slope protection construction. B. Substructure construction: After accurate measurement and layout, the substructure components of the bridge, such as pile foundations, abutments, and permanent bearings, are constructed in sequence. C. Construction of steel piers: After excavating the soil 50cm below the bottom of the beam, test the bearing capacity of the foundation. If it does not meet the requirements, replace the foundation. Then, construct two precast steel piers on both sides of the abutment. The height of the steel piers is 10cm higher than the permanent supports on both sides of the abutment. D. In-situ prefabrication of beams: The prefabrication process, including steel bar binding, formwork installation, and concrete pouring, is completed on the qualified steel pedestal. E. Curing and tensioning: The precast beams are cured for seven days. After curing, the prestressing tensioning is carried out according to the design requirements. F. Lateral movement and beam lowering: After the precast beam is lifted by the lifting device, the tensioned precast beam is laterally moved to the designed installation position by the lateral movement device below the lifting device, and then the precast beam is lowered to the top of the permanent support by the lifting device. G. Subsequent construction: After all precast beams are installed, the bridge deck system and ancillary works will be constructed. The steel piers can be removed and the main roadbed will be excavated to the design elevation. Cross-operations at different levels are prohibited throughout the construction process.

2. The method for erecting in-situ precast beams according to claim 1, characterized in that: The slope protection described in step A adopts one of the following: shotcrete and anchor, grouted rubble masonry, or steel support, which is suitable for the geological conditions of silty clay, sandstone and mudstone interlayers at the bridge site.

3. The method for erecting in-situ precast beams according to claim 1, characterized in that: The steel pedestal mentioned in step C is made of H-beams, I-beams or box-shaped steel. After the steel pedestal is constructed, a load-bearing capacity test must be conducted. Only after the test is passed can the beam prefabrication work be carried out.

4. The method for erecting in-situ precast beams according to claim 1, characterized in that: The lateral movement device described in step F has the functions of lateral movement, limiting and precise positioning, which can prevent the precast beam from being moved too far laterally. During the lateral movement of the precast beam, a support structure is set to prevent the beam from overturning. The support structure is a steel pipe support or a steel profile support.

5. The method for erecting in-situ precast beams according to claim 1, characterized in that: In step F, the lateral movement and lowering of the beam involves installing a lateral movement device with integrated lifting function on both sides of the permanent support, and directly completing the lateral movement and lowering of the precast beam through this device.

6. The method for erecting in-situ precast beams according to claim 1, characterized in that: In step F, the beam is lowered by setting up a transverse track under the steel pedestal and anchoring it to the foundation. Hydraulic jacks are installed on both sides of the track to provide transverse force. After the precast beam is moved laterally, it is lowered to the sand bucket temporary supports on both sides of the permanent support. The beam is then lowered through the sand bucket temporary supports.

7. The method for erecting in-situ precast beams according to claim 1, characterized in that: In step F, the beam is lowered by setting a transverse track under the steel pedestal and anchoring it to the foundation. Hydraulic jacks are installed on both sides of the track to provide transverse force. At the intersection of the steel pedestal and the precast beam, additional jacks are added as a special lifting device to complete the precise lowering of the precast beam.

8. The method for erecting in-situ precast beams according to claim 1, characterized in that: The precast beam is a T-beam, which is suitable for the superstructure of the vehicular overpass. The precast beam is precast on-site at the bridge site, eliminating the need for off-site precasting and beam transportation.

9. The method for erecting in-situ precast beams according to claim 8, characterized in that: The precast beams are erected in conjunction with the steel pedestals, lateral movement devices, and lifting devices at the bridge site. The steel pedestals are compatible with the dimensions and loads of the precast beams, and the steel pedestals are modular, detachable, and reusable.

10. The method for erecting in-situ precast beams according to claim 9, characterized in that: The contact surface between the beam end of the precast beam and the permanent support is provided with a leveling pad, which is made of mortar or steel plate to ensure the flatness and stability of the precast beam during erection.

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