Modular construction technology for cast-in-situ cross beam of high-pile wharf

Abstract

The application discloses a kind of high-pile wharf cast-in-place crossbeam modular construction technology, comprising: construction preparation and platform erection, steel platform modular assembly, operation platform bottom die installation, PHC pile head cutting, pile core construction, lower crossbeam reinforcement and formwork system construction, lower crossbeam concrete pouring and maintenance and side mold dismantling and bottom die steel platform reverse sequence disassembly;Wherein operation platform bottom die installation is carried out by mold A, mold B and mold C circulating sequence, form the bottom die laying scheme corresponding to pile distribution, according to laying scheme installation platform bottom die, then install steel guardrail, footboard on both sides of platform, set personnel up and down stair, form standardization water operation platform, mold A and mold B are unified specification symmetrical processing lightweight fixed steel mold, mold C is the lightweight fixed steel mold of adjusting unequal spacing, and mold C and mold A / mold B are different in specification.

Description

Technical Field

[0001] This invention relates to the field of high-pile wharf technology, and in particular to a modular construction process for cast-in-place crossbeams of high-pile wharves. Background Technology

[0002] High-pile wharves are a widely used wharf structure in port engineering. The upper load is transferred to the pile foundation through the crossbeams. Therefore, the construction quality of the crossbeams directly affects the overall structural safety of the wharf. The construction of cast-in-place crossbeams for high-pile wharves requires the erection of a bottom formwork support system on the water, relying on the already constructed pile foundations to transfer the construction load to the pile body.

[0003] Currently, the bottom formwork support system for cast-in-place crossbeams of high-pile wharves mainly includes the following methods: Corbel support method: Corbels are welded to the pile body, and longitudinal beams and distribution beams are erected on the corbels to form a support platform. This method has a simple structure, but it involves underwater welding, which is difficult to construct. In addition, welding will damage the anti-corrosion coating on the surface of the steel pipe pile, making later repair difficult. Round steel suspension method: The bottom formwork is suspended from the top of the pile using precision rolled threaded steel or round steel. This method saves materials, but the bottom formwork is difficult to remove, and steel bar ends will be left at the bottom of the crossbeam, which is difficult to handle and can easily lead to quality problems. Inverted bottom formwork method: The bottom formwork is supported by an inverted lifting mechanism, and the existing piles are used as the load-bearing foundation. This method is less affected by tides and the quality of the crossbeams can be controlled, but the structure is complex.

[0004] In addition, existing steel clamp support systems typically use clamp brackets to support the main beam to form the bottom formwork platform. However, in actual construction, the spacing between adjacent pile foundations is often not completely consistent. Due to design requirements or construction deviations, the center distance between adjacent pile foundations within the same frame may differ. In this case, existing technologies usually use on-site cutting of bamboo plywood to fill the gaps or custom-made non-standard bottom formwork. The former is inefficient and has poor standardization, while the latter is costly and has poor turnover.

[0005] Therefore, there is an urgent need for a modular construction process for cast-in-place beams of high-pile wharves to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a modular construction process for cast-in-place crossbeams of high-pile wharves that solves the above-mentioned problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A modular construction process for cast-in-place crossbeams of high-pile wharves, characterized by comprising: S1. Construction preparation and platform construction; Prefabricate standard templates A, B, and C of different widths; complete the re-measurement of the PHC pile top elevation; and install steel clamps and clamp brackets on the PHC piles. S2, modular assembly of steel platform; Double H-beams are used as the main beams, which are erected on the brackets. Tie rods and steel pipes are installed between the main beams. The secondary beams are laid at a center-to-center spacing of 35cm and are fixed to the main beams with U-shaped clips. S3. Installation of the bottom formwork for the work platform; In step S1, the three templates are installed in a cyclical sequence of "template A, template B, and template C" to form the platform bottom mold; S4, PHC pile head removal; Cut off the pile head to 20mm from the design elevation, tie it with steel wire rope and discard the cut-off pile head in the designated water area, and then manually chisel off the remaining 20mm protective layer. S5. Pile core construction; The steel bottom tray was installed using the reverse hoisting method. Two hoisting points were set at 1 / 4 of the height of the PHC pile head end. The steel cage was hoisted down to the design position, and finally C35 shrinkage compensating concrete was poured to the top of the pile. S6. Construction of the lower crossbeam reinforcement and formwork system; After the initial setting of the pile core concrete, the lower crossbeam structure and formwork system are constructed. The lower crossbeam reinforcement cage consists of main bars and stirrups. The formwork system includes the bottom formwork in step S3 and the side and end formwork installed in this step. After the side formwork is reinforced into an integral module, a release agent is applied. A grout stop strip is installed between the side formwork and the bottom formwork. The bottom is fixed with a secondary beam tightening device, and the top is equipped with tie rods. The end formwork is reinforced with angle steel. S7. Concrete pouring and curing of the lower crossbeam; The concrete was poured in layers using a ground pump. The pouring time for a single beam was about 2 hours. The layer thickness was ≤500mm, the spacing was 30~50cm, and each layer penetrated ≥5cm into the layer below. S8. Side formwork removal and bottom formwork steel platform dismantling in reverse order; The day after the concrete was poured, based on the test block strength reaching 2.5MPa or above under the same conditions, the connectors, tie rods, and bottom clamping devices were removed and cleaned in sequence, and finally the platform was dismantled in reverse order.

[0008] Preferably, in step S1, template A and template B are lightweight fixed-shape steel molds with uniform specifications and symmetrical processing, and template C is a lightweight fixed-shape steel mold with adjustable unequal spacing, and template C has different specifications from template A / template B.

[0009] Preferably, in step S1, the clamp brackets are arranged perpendicular to the axis of the PHC pile, and the clamp brackets on both sides of the PHC pile are installed symmetrically, horizontally, and coplanarly.

[0010] Preferably, in step S3, grout-stopping strips are pasted at the connection points between templates A and B and the pile foundation, and at the connection points between templates A and B and template C. Joint bolts for tightening the grout-stopping strips are also provided at the joints of templates A, B, and C. Adjusting wooden strips for adjusting non-standard gaps are installed on one side of template C.

[0011] Preferably, the wooden strip is adjusted to be 2-5cm wide.

[0012] Preferably, in step S3, templates A, B, and C are pre-set with lifting points, and lifting lugs are provided at the lifting points.

[0013] Preferably, in step S4, the steel wire is a 6X37-φ24 steel wire rope with a safety factor ≥6 and a sling angle ≤60°.

[0014] Preferably, in step S6, the main reinforcement bars are connected using straight threaded sleeves, and the stirrups are tied point by point.

[0015] Preferably, in step S6, the secondary beam tightening device is a force-bearing component used to tighten and fix the side formwork from the bottom.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses three pre-formed steel molds—template A, template B, and template C—in a cyclical sequence for mold assembly. Templates A and B are lightweight, standardized steel molds of uniform specifications, ensuring efficient and standardized laying of conventional, equidistant sections. Template C is specifically used for unequal-spacing transition sections, absorbing spacing errors caused by pile design deviations or construction misalignments. It is supplemented with wooden strips to fill any remaining tiny gaps, forming a complete bottom mold laying scheme with standardized sequence coverage and local fine-tuning. The combination of the three templates can cover various pile spacing conditions without the need for temporary cutting on a water-based work platform. This solves the technical problems of low standardization and poor on-site cutting efficiency in existing bottom mold laying technologies, realizing factory prefabrication and on-site assembly of bottom mold laying. 2. This invention adopts a three-stage connection method: installing the steel bottom tray using the reverse hoisting method, first pouring the pile core concrete up to the bottom of the lower crossbeam, and then completing the crossbeam pouring before the initial setting of the lower layer of concrete. This method not only suppresses the generation of shrinkage cracks through layered pouring, but also ensures the integrity of the pile core and crossbeam by completing the upper layer pouring before initial setting. At the same time, the use of the reverse hoisting method for the steel bottom tray avoids the defect that conventional supports at the bottom of the pile core cannot be removed, effectively improving the structural durability and construction quality of the crossbeam root. Attached Figure Description

[0017] Figure 1 This is a construction diagram of the bottom formwork of the work platform in this invention.

[0018] Figure 2 This is a schematic diagram of the structure of template A in this invention.

[0019] Figure 3 This is a schematic diagram of the structure of template C in this invention.

[0020] Figure 4 This is a cross-sectional structural diagram of the connection between adjacent templates in this invention.

[0021] Explanation of reference numerals in the attached drawings: 1. Distribution beam; 2. Longitudinal connecting rod; 3. Steel panel; 4. Splicing bolt; 5. Grout stop strip; 6. Adjusting wooden strip; 7. Lifting point; 8. Pile foundation. Detailed Implementation

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. In the following detailed description, many specific details are set forth for ease of explanation to provide a full understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments may be implemented without these specific details. Furthermore, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising”, “including”, etc., as used herein indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0024] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted in a manner consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0025] Please see the appendix Figure 1 - Appendix Figure 4 This invention provides a modular construction process for cast-in-place crossbeams of high-pile wharves, which specifically includes the following steps.

[0026] S1. Construction Preparation and Platform Erection Bottom formwork design and selection: Based on the design pile location plan, the center distance between 8 adjacent piles is calculated. For sections with regular spacing, standard formwork A and standard formwork B are prefabricated. For sections with local unequal spacing, adjustable formwork C is prefabricated. Template A and Template B are lightweight, symmetrically machined steel molds of uniform specifications. Template C is a lightweight, symmetrically machined steel mold with adjustable spacing, and Template C has different specifications from Template A and Template B. Templates A, B, and C have the same main structure, consisting of distribution beam 1, longitudinal connecting rod 2, steel panel 3, splicing bolts 4, and grout stop strip 5. The difference is that templates A and B have circular notches at different positions that fit with PHC piles. Template C differs from templates A and B only in length specifications, depending on the spacing section. Templates A, B, and C are all made of Q235B steel. Pile location re-measurement and platform support: Based on the design drawings, the elevation of the top of the PHC pile was re-measured. A barge crane was used in conjunction with a construction raft to install steel clamps and clamp brackets on the PHC pile, and safety rope anchor points were set on the top surface of the clamp brackets to fix the rings. The clamp brackets are tightened symmetrically and evenly with high-strength bolts at a torque of 500 N·m to ensure the stability and consistent elevation of the support system. After installation, the height difference of the top surface of each clamp bracket is re-measured with a level instrument, and the height difference error is controlled within ±5 mm. The clamp brackets are arranged perpendicular to the axis of the PHC pile, and the clamp brackets on both sides of the PHC pile are installed symmetrically, horizontally, and coplanarly to ensure that the force axis is consistent with the load transfer direction of the cap beam.

[0027] S2, Modular assembly of steel platform Double-section H-beams are used as the main beams and erected on the clamp brackets. Tie rods and steel pipe supports are installed between the main beams to prevent lateral overturning. The support spacing is arranged in rows of 1.5m, which together with the tie rods form a lateral constraint. The secondary beams are made of No. 10 channel steel and are laid at a center-to-center spacing of 35cm. The secondary beams are fixed to the main beams by U-shaped buckles. The double-section H-beam has a web height of 400mm, a flange width of 200mm, and a nominal diameter of 16mm for the tie rod.

[0028] S3, Installation of the bottom formwork for the work platform In step S1, the three templates are matched in a cyclical sequence of "template A, template B, and template C" to form a bottom formwork laying scheme corresponding to the pile location distribution. Grout-stopping strips 5 are pasted at the connection points between template A and template B and the pile foundation 8, and at the connection points between template A and template B and template C. Joint bolts 4 are installed at the joints of template A, template B, and template C to tighten the grout-stopping strips 5. Adjusting wooden strips 6, 2-5cm wide, are installed on one side of template C to adjust non-standard gaps. The bottom formwork of the platform is installed according to the laying scheme. During bottom formwork installation, the joints between templates are sealed with grout-stopping strips 5 to ensure no grout leakage. After the templates are installed, the remaining gaps between template C and the pile location sidewalls are adjusted and filled with 2-5cm wide adjusting wooden strips 6. Rubber strips are used to seal the gaps between the adjusting wooden strips and the steel formwork, achieving complete closure of the bottom formwork working surface. Then, steel guardrails and toe boards are installed on both sides of the platform, and ladders are set up to allow personnel to ascend and descend, forming a standardized water operation platform. The templates A, B, and C are pre-set with lifting points 7, and lifting lugs are provided at the lifting points 7. The dimensions of templates A and B are 1.5m x 0.8m x 0.006m, and the weight of a single piece is about 110kg. Therefore, the lifting points 7 and lifting lugs must be set in advance for hoisting during construction.

[0029] S4, PHC pile head removal To avoid damaging the prestressed main reinforcement of the pile body when cutting off the pile head, a clamp-type pile cutter was used to cut off the pile head to 20mm from the design elevation. A 6X37-φ24 steel wire rope with a self-locking shackle was used for binding. The safety factor of the steel wire rope was ≥6. The pile head was lifted off by the main hook of the barge crane with a sling angle ≤60°. The auxiliary hook assisted in releasing the rope. The cut-off pile head was abandoned in a designated water area. Then, a pneumatic pick was used to manually chisel away the remaining 20mm protective layer until the flatness of the pile top met the design requirement of a height difference ≤5mm.

[0030] S5, Pile Core Construction The steel bottom tray was installed using a reverse hoisting method. The circular steel bottom tray with a diameter of 780mm and a thickness of 6mm was suspended at the designed bottom elevation of the pile core by four symmetrically arranged φ25mm hoisting rods. The upper end of the hoisting rods was fixed to the top of the pile by hooks. Two hoisting points were set at the end of the PHC pile head. Then, the steel cage was hoisted and slowly lowered to the designed position. Finally, C35 shrinkage-compensating concrete was poured to the top of the pile and compacted with a φ30mm vibrator. The remaining pile core and crossbeam concrete were poured before the initial setting of the lower layer of concrete, so that the pile core and crossbeam formed an integral structure.

[0031] S6. Construction of the lower crossbeam reinforcement and formwork system After the initial setting of the pile core concrete, the construction of the lower crossbeam structure begins. The lower crossbeam reinforcement cage consists of longitudinal main reinforcement bars and transverse stirrups. The formwork system includes the bottom formwork that was laid in place with the platform in step 2, as well as the side formwork and end formwork installed in this step. The main reinforcement bars are connected by straight threaded sleeves, and the stirrups are tied point by point. After the formwork arrives on site, the side formwork is reinforced into an integral module for inspection. After passing the inspection, a release agent is applied. A grout stop strip 5 is installed between the side formwork and the bottom formwork. The bottom is fixed by a secondary beam tightening device, and the top is equipped with tie rods. The end formwork is reinforced with angle steel to ensure that the formwork system is tight and stable. The secondary beam tightening device is a load-bearing component used to tighten and fix the side formwork from the bottom. The secondary beam tightening device can be freely selected according to the actual construction. For example, in actual projects, a component that can be adjusted and tightened by rotating bolts is set between the bottom of the side formwork and the secondary beam.

[0032] S7. Concrete pouring and curing of the lower crossbeam The concrete is poured in layers using a ground pump, with the interval between layers ≤ the initial setting time of the concrete. The pouring time for a single beam is about 2 hours, and the layer thickness is ≤ 500mm. The immersion vibrator is inserted quickly and withdrawn slowly, with a spacing of 30~50cm. Each layer is inserted ≥ 5cm into the layer below to ensure the concrete is dense. During insertion, it is strictly forbidden to touch the embedded parts, steel bars and formwork. After scraping off the laitance on the top surface, the surface is plastered twice and compacted, and then covered with geotextile and watered for curing.

[0033] S8. Side formwork removal and bottom formwork steel platform dismantling in reverse order; The day after the concrete was poured, based on the test block strength reaching 2.5MPa or above under the same conditions, the connectors, tie rods, and bottom clamping devices were removed in sequence and then lifted away and cleaned by a barge crane. After 7 days of curing and reaching 80% strength, a hand-operated hoist and sling are installed using pre-embedded lifting lugs. Construction workers then enter the bottom to operate, sequentially loosening the clamps, lowering the bottom formwork platform, and dismantling the guardrails, formwork, and secondary beams layer by layer. Finally, a barge crane lifts the main beam and clamps, completing the reverse dismantling of the platform.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A modular construction process for cast-in-place crossbeams of a high-pile wharf, characterized in that, include: S1. Construction preparation and platform construction; Prefabricate standard templates A, B, and C of different widths; complete the re-measurement of the PHC pile top elevation; and install steel clamps and clamp brackets on the PHC piles. S2, modular assembly of steel platform; Double H-beams are used as the main beams, which are erected on the brackets. Tie rods and steel pipes are installed between the main beams. The secondary beams are laid at a center-to-center spacing of 35cm and are fixed to the main beams with U-shaped clips. S3. Installation of the bottom formwork for the work platform; In step S1, the three templates are installed in a cyclical sequence of "template A, template B, and template C" to form the platform bottom mold; S4, PHC pile head removal; Cut off the pile head to 20mm from the design elevation, tie it with steel wire rope and discard the cut-off pile head in the designated water area, and then manually chisel off the remaining 20mm protective layer. S5. Pile core construction; The steel bottom tray was installed using the reverse hoisting method. Two hoisting points were set at 1 / 4 of the height of the PHC pile head end. The steel cage was hoisted down to the design position, and finally C35 shrinkage compensating concrete was poured to the top of the pile. S6. Construction of the lower crossbeam reinforcement and formwork system; After the initial setting of the pile core concrete, the lower crossbeam structure and formwork system are constructed. The lower crossbeam reinforcement cage consists of main bars and stirrups. The formwork system includes the bottom formwork in step S3 and the side and end formwork installed in this step. After the side formwork is reinforced into an integral module, a release agent is applied. A grout stop strip is installed between the side formwork and the bottom formwork. The bottom is fixed with a secondary beam tightening device, and the top is equipped with tie rods. The end formwork is reinforced with angle steel. S7. Concrete pouring and curing of the lower crossbeam; The concrete was poured in layers using a ground pump. The pouring time for a single beam was about 2 hours. The layer thickness was ≤500mm, the spacing was 30~50cm, and each layer penetrated ≥5cm into the layer below. S8. Side formwork removal and bottom formwork steel platform dismantling in reverse order; The day after the concrete was poured, based on the test block strength reaching 2.5MPa or above under the same conditions, the connectors, tie rods, and bottom clamping devices were removed and cleaned in sequence, and finally the platform was dismantled in reverse order.

2. The modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S1, template A and template B are lightweight fixed-shape steel molds with uniform specifications and symmetrical processing, while template C is a lightweight fixed-shape steel mold with adjustable unequal spacing, and template C has different specifications from template A / template B.

3. The modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S1, the clamp brackets are arranged perpendicular to the axis of the PHC pile, and the clamp brackets on both sides of the PHC pile are installed symmetrically, horizontally, and coplanarly.

4. A modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S3, grout-stop strips are pasted at the connection points between templates A and B and the pile foundation, and at the connection points between templates A and B and template C. Joint bolts for tightening the grout-stop strips are also installed at the joints of templates A, B, and C. Adjustment strips for adjusting non-standard gaps are installed on one side of template C.

5. A modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 4, characterized in that: Adjust the wooden strips to a width of 2-5cm.

6. A modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S3, templates A, B, and C are pre-set with lifting points, and lifting lugs are provided at the lifting points.

7. A modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S4, the steel wire used is 6X37-φ24 steel wire rope, the safety factor of the steel wire rope is ≥6, and the sling angle is ≤60°.

8. A modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S6, the main reinforcement bars are connected using straight threaded sleeves, and the stirrups are tied point by point.

9. A modular construction process for cast-in-place crossbeams of a high-pile wharf according to claim 1, characterized in that: In step S6, the secondary beam clamping device is a force-bearing component used to clamp and fix the side formwork from the bottom.

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