Trestle-free rapid assembling and disassembling construction method for offshore high-rise pile cap steel hanging box

Abstract

The invention discloses a trestle-free rapid assembling and disassembling construction method for an offshore high-rise pile cap steel hanging box. The trestle-free rapid assembling and disassembling construction method comprises the following steps that S1, the steel hanging box is machined in a factory and pre-assembled; s2, transporting the steel hanging box to an assembling platform at a bridge site, and performing total assembling on the steel hanging box and the prefabricated bottom plate through connecting bolts; s3, hoisting the steel hoisting box to the pier position through a crane ship, and mounting the steel hoisting box at the pier position; s4, after the lower portion of the steel hanging box is in place, a blocking steel plate and a shear bracket are welded, and the shear bracket is located between the blocking steel plate and the steel pipe pile; s5, bottom sealing concrete is poured; s6, a bearing platform is poured; and S7, the hanging box is dismantled. A factory-like and modular process is adopted for the steel hanging box, after the river steel-concrete combined cofferdam is modularly machined in a factory, the steel-concrete combined cofferdam is generally spliced on an offshore splicing platform, then the steel-concrete combined cofferdam is hoisted in place at a time through a large crane ship, the construction efficiency is greatly improved, meanwhile, a temporary trestle is omitted, the overall hoisting technology of the crane ship is utilized, and the construction cost is reduced. The occupation on channels and the dependence on large equipment are reduced, and the construction cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of offshore high pile cap construction, and in particular to a method for rapid assembly and disassembly of an offshore high pile cap steel hoisting box without a trestle. Background Art

[0002] Traditional offshore steel pipe pile high pile foundation construction usually adopts the construction method of steel cofferdam or steel hanging box combined with trestles, which requires reliance on large-scale lifting equipment and temporary trestles for material transportation and lifting. It has problems such as long construction period, high cost, great impact on navigation, and high water pollution.

[0003] Especially in strong tide and rapid current environments, the steel hanging box is heavy and has poor stability, and requires complex anchoring measures to resist the impact of water flow, which further increases the difficulty of construction. Summary of the Invention

[0004] The purpose of the present application is to provide a method for rapid assembly and disassembly of an offshore high-pile foundation steel hoisting box without a pier. In the present application, the steel hoisting box adopts a factory-based and modular process. After modular processing on the steel-concrete composite cofferdam in the factory, it is assembled on the offshore assembly platform and then hoisted into place at one time by a large crane ship. The use of the steel-concrete composite cofferdam solves a series of problems such as the difficulty in dismantling conventional steel bottom plates, water pollution, and electrical connectivity of sacrificial anodes. In addition, by optimizing the internal support system of the steel hoisting box, a cantilever beam structure with both the function of a shelving beam and a hoisting device is set up, and a traversable bolted hanger structure is adopted to save steel usage, achieve efficient installation, precise positioning and rapid dismantling of the steel hoisting box, significantly shorten the construction period and reduce construction costs.

[0005] In the first aspect, the present application provides a method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle, which adopts the following technical solutions: A method for rapid assembly and disassembly of an offshore high-pile foundation steel hanging box without a trestle comprises the following steps: S1. Process the steel hanging box and pre-assemble it in the factory; S2. Transport the steel hanging box to the assembly platform at the bridge location and assemble it with the prefabricated bottom plate through connecting bolts; S3. Hoist the steel hanging box to the pier position by a crane ship and install it at the pier position; S4. After the bottom of the steel hanging box is in place, weld the sealing steel plate and shear bracket. The shear bracket is located between the sealing steel plate and the steel pipe pile. S5. Pour bottom seal concrete to realize the system conversion of steel-concrete composite cofferdam; S6. Casting the foundation pile; S7. Remove the connecting bolts between the steel hanging box and the prefabricated base plate and dismantle the hanging box.

[0006] By adopting the above technical solution, the steel hoisting box of this process adopts a factory-based and modular process. After modular processing on the steel-concrete composite cofferdam in the factory, it is assembled on the assembly platform at sea and then hoisted into place in one go using a large crane ship, which greatly improves construction efficiency. At the same time, the temporary pier is eliminated and the overall hoisting technology of the crane ship is used to reduce the occupation of the waterway and the dependence on large equipment, thereby reducing construction costs.

[0007] Optionally, the prefabricated base plate includes an outer beam and an inner beam frame, the outer beam is arranged to fit the inner wall of the steel hanging box, the inner beam frame is arranged inside the outer beam, and a plurality of vacant holes are provided in the inner beam frame, and the vacant holes are used for steel pipe piles to pass through.

[0008] Through the above technical solution, the reliability of the connection between the inner beam frame and the steel hanging box is guaranteed by the outer beam, and the vacant holes provided on the inner beam frame facilitate avoiding interference with the steel pipe piles when the steel hanging box is lowered.

[0009] Optionally, the prefabricated base plate is made by pouring concrete.

[0010] Through the above technical solution, the prefabricated base plate made of concrete solved a series of problems such as the difficulty of dismantling conventional steel base plates, water pollution, and electrical connection of sacrificial anodes. In addition, on the assembly platform, the steel hanging box wall panels were used as the outer mold of the concrete prefabricated base plate, which saved the template investment of the prefabricated base plate, effectively strengthened the fit between the steel hanging box wall panels and the prefabricated base plate, and accelerated the overall assembly progress of the steel-concrete composite cofferdam.

[0011] Optionally, a side sealing plate is provided at the bottom of the steel hanging box, and a portion of the side sealing plate abuts against the bottom of the outer beam.

[0012] Through the above technical solution, the side-wrapped bottom structure is adopted, which can effectively ensure the fit between the concrete prefabricated bottom plate and the inner wall of the steel hanging box, enhance the waterproof ability of the cofferdam, and solve the unsightly problem caused by the prefabricated bottom plate exceeding the base contour due to the conventional bottom wrapping side.

[0013] Optionally, in step S4, at low tide, a sealing steel plate is constructed, and a receiving hole is provided on the sealing steel plate. During construction, the sealing steel plate is put on the steel pipe pile through the receiving hole, and then the sealing steel plate is connected to the inner beam frame, and a shear corbel is welded between the sealing steel plate and the steel pipe pile.

[0014] Through the above technical solution, the bottom of the steel hanging box can be sealed by blocking the steel plate, and the relative fixation of the shear corbel and the inner beam frame can be achieved.

[0015] Optionally, since the steel pipe piles are set at an angle, the sealing steel plate needs to be installed at an angle, and the size of the receiving hole on the sealing steel plate needs to be slightly larger than the steel pipe piles. This results in an inevitable gap between the receiving hole and the steel pipe pile after the sealing steel plate is installed.

[0016] In order to seal the gap between the receiving hole and the steel pipe pile, a water-swelling rubber strip is fixedly connected to the bottom of the shear corbel, and the water-swelling rubber strip is installed in the gap between the receiving hole and the steel pipe pile. The same steel pipe pile corresponds to multiple shear corbels, and the multiple shear corbels are arranged along the circumference of the steel pipe pile. The cross-section of the shear corbel is a right-angled trapezoid, with the large end located at the top, and the small end of the shear corbel is fixedly connected to the water-swelling rubber strip. During installation, the water-swelling rubber strip is inserted from top to bottom into the gap between the steel pipe pile and the receiving hole. The small end of the shear corbel then enters the side wall of the receiving hole and the steel pipe pile. As the shear corbel continues to be inserted, the inclined surface of the shear corbel contacts the side wall of the receiving hole. Multiple shear corbels work together to relatively fix the position of the steel pipe pile and the sealing steel plate. Finally, the shear corbel is welded to the steel pipe pile and the sealing steel plate. When the shear corbel is placed between the receiving hole and the steel pipe pile, it can be achieved by knocking.

[0017] In addition, a circular steel mesh is fixed to the side wall of the shear corbel. This mesh is positioned above the water-swelling strip and within the gap between the steel pipe pile and the receiving hole. Once the shear corbel is secured, sealing concrete is poured between the receiving hole and the steel pipe pile. The circular steel mesh serves as a framework for the sealing concrete, enhancing its strength after formation while also alleviating the pressure from the water-swelling strip. Once the sealing concrete is formed, it is ready for the bottom seal concrete. Due to the large amount of bottom seal concrete poured, the sealing concrete effectively prevents the bottom seal concrete from breaking through the water-swelling strip. The width of the circular steel mesh decreases from top to bottom to allow it to fit into the gap between the steel pipe pile and the receiving hole. The mesh also deforms to accommodate gaps of varying sizes (due to the tilted steel pipe pile, the gap between the steel pipe pile and the receiving hole varies in size).

[0018] It should be noted that the above construction needs to be carried out at low tide, when the water level is lower than the sealing steel plate. After the above construction is completed, when the water level rises, the water-expandable rubber strip can expand when it comes into contact with water, further improving the reliability of the sealing. At the same time, the water-expandable rubber strip is equivalent to the bottom formwork of the sealing concrete.

[0019] Optionally, in step S5, before pouring the bottom concrete, the bond strength of the bottom concrete is enhanced by arranging circumferential steel bars around the steel pipe piles. When pouring the bottom concrete, the side wall of the steel hanging box is used as a template for pouring the bottom concrete.

[0020] By adopting the above technical solution, the side wall of the steel hanging box is used as the template for pouring the bottom concrete, which can further reduce the investment in the template. At the same time, the annular steel bars can increase the bond strength of the bottom concrete, thereby increasing the bonding strength between the bottom concrete and the steel pipe piles.

[0021] Optionally, in step S5, a horizontally arranged cantilever beam is connected to the inner wall of the steel hanging box. After the steel hanging box is lowered to the pier position, the cantilever beam is located on the top of the steel pipe pile. A number of suspension rods are connected to the cantilever beam, and the suspension rods are connected to the inner beam skeleton. After the strength of the bottom concrete meets the requirements, the rotatable cantilever beam and suspension rods are removed.

[0022] By adopting the above technical solution, the cantilever beam structure with the functions of both a placing beam and a sling is placed on the top of the steel pipe pile, thereby realizing the rapid lowering of the steel hanging box into position.

[0023] Optionally, in step S6, water is first pumped out of the steel hanging box to form a dry working environment, and the deck of the small crane ship is used as a transfer platform for steel bars and small formwork materials.

[0024] Through the above technical solution, water is pumped out from the steel hoisting box to form a dry working environment, which facilitates more efficient and higher-quality construction. Using the deck of a small crane ship as a transfer platform for steel bars and small formwork materials effectively saves the investment in transport ships and speeds up the construction organization of the foundation.

[0025] Optionally, in step S7, gas cutting is used to remove the connecting bolts between the steel hanging box and the prefabricated bottom plate at low tide.

[0026] By adopting the above technical solution, the dismantling of the steel hanging box is accelerated, and the reuse of the steel hanging box is achieved through modular disassembly.

[0027] Optionally, in step S3, the steel box is roughly positioned using an anchoring vessel and an anchor cable system, and the position is dynamically adjusted in combination with GPS and a laser rangefinder to lower the steel box.

[0028] Through the above technical solution, combined with multi-sensor monitoring and dynamic adjustment technology, the positioning accuracy of the steel hanging box can be improved to adapt to the strong tide and rapid current environment.

[0029] In summary, this application includes at least one of the following beneficial technical effects: 1. This process uses a factory-based, modularized process. After modularization on the inland steel-concrete composite cofferdam, the steel box is assembled on an offshore assembly platform and then hoisted into place in one go using a large crane ship. This significantly improves construction efficiency and eliminates temporary trestles. Utilizing crane ship-based overall hoisting technology reduces waterway occupation and reliance on large equipment, thereby lowering construction costs. 2. The outer beam ensures the reliability of the connection between the inner beam frame and the steel hanging box. The empty holes set on the inner beam frame are convenient for avoiding interference with the steel pipe piles when the steel hanging box is lowered; 3. The precast concrete base plate solves a series of problems with conventional steel base plates, such as difficulty in removal, water pollution, and electrical connectivity of sacrificial anodes. In addition, on the assembly platform, the steel hanging box wall panels are used as the outer formwork of the concrete precast base plate, which saves the template investment for the precast base plate, effectively improves the fit between the steel hanging box wall panels and the precast base plate, and speeds up the overall assembly progress of the steel-concrete composite cofferdam. 4. The side-wrapped bottom structure can effectively ensure the fit between the precast concrete bottom plate and the inner wall of the steel hanging box, enhance the waterproof ability of the cofferdam, and solve the unsightly problem caused by the precast bottom plate exceeding the outline of the platform due to the conventional bottom wrapping; 5. The sealing steel plate facilitates the bottom sealing of the steel hanging box and can also achieve the relative fixation of the shear corbel and the inner beam frame. The side wall of the steel hanging box serves as the formwork for pouring the bottom concrete, which can further reduce the investment in formwork. At the same time, the circumferential steel bars can increase the bond strength of the bottom concrete, thereby increasing the bonding strength between the bottom concrete and the steel pipe piles. 6. The cantilever beam structure, which serves as both a support beam and a sling, is placed on top of the steel pipe pile, enabling the steel hanging box to be quickly lowered into place; 7. Pumping out water from the steel hoisting box creates a dry working environment for more efficient and higher-quality construction. Using the deck of a small crane ship as a transfer platform for steel bars and small formwork materials effectively saves on the investment in transport ships and speeds up the construction organization of the foundation. 8. Combine multi-sensor monitoring and dynamic adjustment technology to improve the positioning accuracy of the steel hanging box and adapt to strong tide and rapids environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a side view cutaway schematic diagram of the steel hanging box in the present invention.

[0031] Figure 2 It is a top view schematic diagram of the steel hanging box in the present invention.

[0032] Figure 3 It is a schematic diagram of the three-dimensional structure of the shear corbel in the present invention.

[0033] Figure 4 It is a schematic diagram of the cross-sectional structure of the water-swellable rubber strip and the shear corbel in the present invention.

[0034] In the figure, 1. Steel hanging box; 11. Side cladding plate; 2. Steel pipe piles; 21. Circumferential reinforcement; 3. Cap; 4. Precast base plate; 41. Outer beam; 42. Inner beam skeleton; 43. Vacant hole; 44. Sealing steel plate; 45. Shear corbel; 46. Accommodation hole; 47. Water-swelling rubber strip; 48. Circular steel mesh; 5. Cantilever beam; 51. Hanging rod. DETAILED DESCRIPTION

[0035] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0036] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be broadly understood, for example, to mean fixed, removable, or integral; mechanically or electrically connected; directly or indirectly through an intermediary; or internally connected between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Example 1 In a first aspect, the present application discloses a method for rapid assembly and disassembly of a steel hoisting box of an offshore high-pile foundation without a trestle.

[0038] A method for rapid assembly and disassembly of offshore high pile cap steel hoisting box without trestle, referring to Figures 1 to 4 , including the following steps: S1. Processing and pre-assembling the steel hanging box 1 in the factory; S2. Transport the steel box 1 to the assembly platform at the bridge site and assemble it with the precast base plate 4 using connecting bolts. The precast base plate 4 includes an outer beam 41 and an inner beam frame 42. The outer beam 41 is positioned against the inner wall of the steel box 1, and the inner beam frame 42 is positioned within the outer beam 41. The inner beam frame 42 is provided with a number of vacant holes 43 for the steel pipe piles 2 to pass through. The outer beam 41 ensures the reliability of the connection between the inner beam frame 42 and the steel box 1, while the vacant holes 43 on the inner beam frame 42 prevent interference with the steel pipe piles 2 when the steel box 1 is lowered. The precast base plate 4 is made of poured concrete. The precast base plate 4 made of concrete solves a series of problems such as the difficulty in dismantling conventional steel base plates, water pollution, and electrical connectivity of sacrificial anodes. In addition, on the assembly platform, the wall panels of the steel hanging box 1 are used as the outer mold of the concrete precast base plate 4, which saves the template investment of the precast base plate 4, effectively strengthens the fit between the wall panels of the steel hanging box 1 and the precast base plate 4, and speeds up the overall assembly progress of the steel-concrete composite cofferdam. The bottom of the steel hanging box 1 is provided with a side sealing plate, a part of which abuts against the bottom of the outer beam 41. The side bottom structure can effectively ensure the fit between the concrete precast base plate 4 and the inner wall of the steel hanging box 1, enhance the waterproof ability of the cofferdam, and solve the unsightly problem caused by the precast base plate 4 exceeding the outline of the base 3 due to the conventional bottom wrapping side.

[0039] S3. The steel box 1 is hoisted to the pier location using a crane vessel and installed there. During hoisting, the mooring vessel and anchor cable system are used to achieve rough positioning of the steel box 1. GPS and laser rangefinders are used to dynamically adjust the position and lower the steel box 1. Multi-sensor monitoring and dynamic adjustment technology are used to improve the positioning accuracy of the steel box 1 and adapt it to strong tides and rapids.

[0040] S4. After the bottom of the steel hanging box 1 is in place, the sealing steel plate 44 and the shear corbel 45 are welded. The shear corbel 45 is located between the sealing steel plate 44 and the steel pipe pile 2. At low tide, the sealing steel plate 44 is installed to cover the vacant hole 43. The sealing steel plate 44 is provided with a receiving hole 46. During construction, the sealing steel plate 44 is placed on the steel pipe pile 2 through the receiving hole 46. The sealing steel plate 44 is then connected to the inner beam frame 42, and the shear corbel 45 is welded between the sealing steel plate 44 and the steel pipe pile 2. The sealing steel plate 44 facilitates the bottom sealing of the steel hanging box 1 and can also achieve the relative fixation of the shear corbel 45 and the inner beam frame 42.

[0041] Since the steel pipe pile 2 is set at an angle, the sealing steel plate 44 needs to be installed at an angle, and the size of the accommodating hole 46 on the sealing steel plate 44 needs to be slightly larger than the steel pipe pile 2. This results in an inevitable gap between the accommodating hole 46 and the steel pipe pile 2 after the sealing steel plate 44 is installed.

[0042] To seal the gap between the receiving hole 46 and the steel pipe pile 2, a water-swelling rubber strip 47 is fixedly connected to the bottom of the shear corbel 45. The water-swelling rubber strip 47 is installed in the gap between the receiving hole 46 and the steel pipe pile 2. Multiple shear corbels 45 are associated with each steel pipe pile 2, and the multiple shear corbels 45 are arranged along the circumference of the steel pipe pile 2. The cross-section of the shear corbel 45 is a right-angled trapezoid, with the large end located at the top. The small end of the shear corbel 45 is fixedly connected to the water-swelling rubber strip 47. During installation, the water-swelling rubber strip 47 is inserted from top to bottom into the gap between the steel pipe pile 2 and the receiving hole 46. Then, the small end of the shear corbel 45 enters the receiving hole 46 and the side wall of the steel pipe pile 2. As the shear corbel 45 continues to be inserted, the inclined surface of the shear corbel 45 contacts the side wall of the receiving hole 46. The multiple shear corbels 45 cooperate to relatively fix the position of the steel pipe pile 2 and the blocking steel plate 44. Finally, the shear corbel 45 is welded to the steel pipe pile 2 and the blocking steel plate 44. The shear corbel 45 can be placed between the receiving hole 46 and the steel pipe pile 2 by knocking.

[0043] Furthermore, an annular steel mesh 48 is fixedly attached to the sidewall of the shear corbel 45. This mesh is positioned above the water-swelling strip 47 and within the gap between the steel pipe pile 2 and the receiving hole 46. After the shear corbel 45 is secured, plugging concrete is poured between the receiving hole 46 and the steel pipe pile 2. The annular steel mesh 48 serves as a framework for the plugging concrete, enhancing its strength after formation while also relieving pressure from the water-swelling strip 47. This allows for the preparation of the bottom seal concrete. Due to the large amount of bottom seal concrete poured, the plugging concrete effectively prevents the bottom seal concrete from breaking through the water-swelling strip 47. The width of the annular steel mesh 48 decreases from top to bottom to allow it to fit into the gap between the steel pipe pile 2 and the receiving hole 46. The mesh is also deformable to accommodate gaps of varying sizes (due to the inclined arrangement of the steel pipe pile 2, the gaps between the steel pipe pile 2 and the receiving hole 46 vary in size).

[0044] It should be noted that the above construction needs to be carried out at low tide, when the water level is lower than the sealing steel plate 44. After the above construction is completed, when the water level rises, the water-swelling rubber strip 47 can expand when it comes into contact with water, further improving the reliability of the sealing. At the same time, the water-swelling rubber strip 47 is equivalent to the bottom formwork of the sealing concrete.

[0045] S5. Pour the bottom concrete, completing the system conversion to a steel-concrete composite cofferdam. Before pouring the bottom concrete, circumferential reinforcement 21 is installed around the steel pipe piles 2 to enhance the concrete's bond strength. During the pouring of the bottom concrete, the side walls of the steel hanging box 1 serve as the formwork for pouring the bottom concrete. Using the side walls of the steel hanging box 1 as the formwork for pouring the bottom concrete further reduces formwork investment. The circumferential reinforcement 21 also increases the concrete's bond strength, thereby strengthening the bond between the bottom concrete and the steel pipe piles 2.

[0046] In addition, a horizontal cantilever beam 5 is connected to the inner wall of the steel hanging box 1. After the steel hanging box 1 is lowered to the pier position, the cantilever beam 5 is located on top of the steel pipe pile 2. Several suspension rods 51 are connected to the cantilever beam 5, which are connected to the inner beam skeleton 42. After the bottom concrete strength meets the requirements, the reusable cantilever beam 5 and suspension rods 51 are removed. By placing the cantilever beam 5 structure, which serves as both a support beam and a suspension device, on top of the steel pipe pile 2, the steel hanging box 1 can be quickly lowered into place.

[0047] S6, pouring the cap 3. When pouring the cap 3, first pump out the water in the steel hanging box 1 to form a dry working environment, and use the deck of the small crane ship as a transfer platform for steel bars and small formwork materials.

[0048] Water is pumped out from the steel hoisting box 1 to create a dry working environment, which facilitates more efficient and higher-quality construction. Using the deck of a small crane ship as a transfer platform for steel bars and small formwork materials effectively saves on the investment in transport ships and speeds up the construction organization of the foundation 3.

[0049] S7. Remove the connecting bolts between the steel hanging box 1 and the prefabricated base plate 4 to dismantle the hanging box. Gas cutting is used to remove the connecting bolts between the steel hanging box 1 and the prefabricated base plate 4 at low tide, which speeds up the dismantling of the steel hanging box 1 and enables the reuse of the steel hanging box 1 through modular disassembly.

[0050] The steel hoisting box 1 of this process adopts a factory-based and modular process. After modular processing on the steel-concrete composite cofferdam in the factory, it is assembled on the assembly platform at sea and then hoisted into place in one go using a large crane ship, which greatly improves construction efficiency. At the same time, the temporary pier is eliminated and the overall hoisting technology of the crane ship is used to reduce the occupation of the waterway and the dependence on large equipment, thereby reducing construction costs.

[0051] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A method for rapid assembly and disassembly of offshore high pile cap steel hanging box without trestle, characterized in that: The steps include: S1. Processing and pre-assembling the steel hanging box (1) in the factory; S2, transporting the steel hanging box (1) to the assembly platform at the bridge location and assembling it with the prefabricated bottom plate (4) through connecting bolts; S3, hoisting the steel hanging box (1) to the pier position by a crane ship, and installing it at the pier position; S4. After the lower part of the steel hanging box (1) is in place, the sealing steel plate (44) and the shear bracket (45) are welded; S5. Pour bottom seal concrete to realize the system conversion of steel-concrete composite cofferdam; S6, pouring the cap (3); S7. Remove the connecting bolts between the steel hanging box (1) and the prefabricated base plate (4) and remove the hanging box.

2. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 1, characterized in that: The prefabricated base plate (4) comprises an outer beam (41) and an inner beam frame (42); the outer beam (41) is arranged in contact with the inner wall of the steel hanging box (1); the inner beam frame (42) is arranged inside the outer beam (41); a plurality of vacant holes (43) are provided in the inner beam frame (42); the vacant holes (43) are used for allowing steel pipe piles (2) to pass through.

3. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 2, characterized in that: The prefabricated base plate (4) is made by pouring concrete.

4. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 3, characterized in that: The bottom of the steel hanging box (1) is provided with a side sealing plate, and a portion of the side sealing plate abuts against the bottom of the outer beam (41).

5. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 4, characterized in that: In step S4, at low tide, a blocking steel plate (44) is constructed. The blocking steel plate (44) is provided with a receiving hole (46). During construction, the blocking steel plate (44) is placed on the steel pipe pile (2) through the receiving hole (46), and then the blocking steel plate (44) is connected to the inner beam frame (42).

6. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 5, characterized in that: In step S5, before pouring the bottom seal concrete, the gripping force of the bottom seal concrete is enhanced by arranging circumferential reinforcement (21) around the steel pipe pile (2). When pouring the bottom seal concrete, the side wall of the steel hanging box (1) is used as a template for pouring the bottom seal concrete.

7. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 6, characterized in that: In step S5, a horizontally arranged cantilever beam (5) is connected to the inner wall of the steel hanging box (1), and a plurality of suspension rods (51) are connected to the cantilever beam (5), and the suspension rods (51) are connected to the inner beam skeleton (42). After the strength of the bottom seal concrete meets the requirements, the rotatable cantilever beam (5) and the suspension rods (51) are removed.

8. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 7, characterized in that: In step S6, water is first pumped out of the steel hanging box (1) to form a dry working environment, and the deck of the small crane ship is used as a transfer platform for steel bars and small formwork materials.

9. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 7, characterized in that: In step S7, at low tide, gas cutting is used to remove the connecting bolts between the steel hanging box (1) and the prefabricated bottom plate (4).

10. The method for rapid assembly and disassembly of a steel hanging box for an offshore high pile cap without a trestle according to claim 1, characterized in that: In step S3, the steel box (1) is roughly positioned using an anchoring vessel and an anchor cable system, and the position is dynamically adjusted in combination with GPS and a laser rangefinder to lower the steel box (1).

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