Multistage air cushion bottom opening caisson submerged ship maintenance platform

Abstract

The invention discloses a multi-stage air cushion open-bottom caisson submerged ship maintenance platform which comprises a first-stage open-bottom caisson, a plurality of second-stage open-bottom caissons, an air pressure adjusting system and a positioning restraint system, and an air cushion flow stabilizing structure is arranged in the caissons. The first-level open-bottom caisson is used for providing overall buoyancy, the multiple second-level open-bottom caissons are used for local buoyancy adjustment and posture control, the air cushion flow stabilizing structure is used for restraining free liquid level fluctuation in the caissons and forming a gas buffer layer, and the air pressure adjusting system is used for independently or cooperatively adjusting air pressure in the caissons. The positioning constraint system is used for limiting the spatial displacement of the platform and providing attitude constraint. Through the combination of the multi-stage caissons and the air cushion steady flow structure, the stable posture control of the submerging and floating platform in the submerging, leveling and supporting and floating operation processes is realized. The device is suitable for underwater maintenance operation of ships in inland rivers, harbor basins and near-shore water areas, and has the advantages of simple structure, high stability, wide application range and the like.

Description

Technical Field

[0001] This invention relates to the field of marine engineering and underwater maintenance equipment technology, and in particular to a multi-stage air cushion open-bottom caisson submersible marine maintenance platform. Background Technology

[0002] Underwater repairs of ships typically rely on dry docks or floating docks. These methods suffer from high construction costs, poor maneuverability, long repair cycles, and significant downtime losses. For inland waterway vessels, a large portion of repair needs are concentrated on localized underwater operations such as propeller replacement, debris removal, zinc ingot replacement, rudder system inspection, and repair of localized corrosion on the hull. If all these tasks were handled in dry dock, it would significantly increase downtime and repair costs.

[0003] Open-bottom caisson type submersible platforms have advantages such as simple structure and adjustable buoyancy, but existing technologies still have the following problems:

[0004] 1. A single caisson structure is prone to free surface oscillation, leading to unstable buoyancy distribution;

[0005] Second, the platform's attitude adjustment capability is insufficient, making it difficult to meet the needs of localized floating maintenance;

[0006] Third, the pressure pump type submersible structure has a large short-term power demand, high energy consumption and slow response.

[0007] Fourth, traditional floating docks are large in size and have poor mobility, making them unsuitable for high-frequency maintenance operations on inland waterways.

[0008] Therefore, it is necessary to provide a submersible ship repair platform that is structurally stable, attitude-adjustable, and has the ability to stabilize current. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a multi-stage air-cushion open-bottom caisson submersible ship repair platform.

[0010] Technical solution: The present invention

[0011] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0012] 1. A multi-stage caisson structure is adopted to achieve separate control of overall buoyancy and local leveling;

[0013] 2. An air cushion flow stabilization structure is installed to suppress free liquid surface oscillation inside the caisson;

[0014] 3. Multiple independent two-stage open-bottom caissons are used for attitude adjustment to improve leveling accuracy;

[0015] 4. The open-bottom caisson structure has a wide buoyancy adjustment range, adapting to ships of different tonnages;

[0016] 5. Compartmentalized air pressure regulation improves system safety and redundancy;

[0017] 6. The positioning constraint system improves the stability of platform operations;

[0018] 7. Enables mobile underwater maintenance operations;

[0019] 8. Underwater partial repairs of ships can be completed without entering dry dock;

[0020] 9. Reduce ship downtime and maintenance costs. Attached Figure Description

[0021] Fig. 1 This is a schematic diagram of the overall structure of the present invention.

[0022] Fig. 2 This is a schematic diagram of the removal of the top plate in this invention.

[0023] Fig. 3 This is a schematic cross-sectional view of a partial step in this invention.

[0024] Fig. 4 This is a schematic diagram of the bottom surface of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0026] See appendix Figs. 1-4 The figure shows that the present invention provides a multi-stage air-cushion open-bottom caisson submersible ship repair platform, the platform comprising:

[0027] 1. Open-bottom caisson.

[0028] Air cushion flow stabilization structure 2.

[0029] Multiple two-stage open-bottom caissons 3.

[0030] Air pressure regulation system.

[0031] Positioning constraint system 4.

[0032] The various systems work together to enable the platform to submerge and adjust its attitude.

[0033] In this embodiment, the first-stage open-bottom caisson 1 is the main structure of the platform, adopting a steel structure box form. Its top and sides are closed, and its bottom is connected to the external water body to form an open-bottom structure. The interior of the first-stage open-bottom caisson 1 forms a gas-liquid coupling cavity. By adjusting the gas pressure inside the caisson, the position of the gas-water interface is changed, thereby changing the drainage volume and generating buoyancy changes.

[0034] The first-stage open-bottom caisson 1 can be a rectangular, circular, or polygonal box structure, with its dimensions determined by the tonnage of the vessel being repaired. The interior of the first-stage open-bottom caisson 1 can be equipped with reinforcing baffles 5 or partitioned structures to improve structural rigidity and reduce free surface effects, while also enhancing the platform's torsional resistance.

[0035] In this embodiment, the air cushion flow stabilizing structure 2 is disposed inside the first-stage open-bottom caisson 1 to suppress free liquid surface fluctuations inside the caisson. The air cushion flow stabilizing structure 2 is preferably a floating structure and can move up and down with changes in the liquid level inside the caisson, thereby dividing the internal space of the caisson into multiple air cushion areas and reducing air-water interface fluctuations.

[0036] The air cushion stabilizing structure 2 can be a floating plate structure, a floating box structure, or a combined floating structure, and is connected to the caisson through a guide structure to restrict lateral movement and allow vertical floating.

[0037] Multiple independent secondary open-bottom caissons 3 are set inside the primary open-bottom caisson 1 or in the key leveling area of ​​the platform. Each secondary open-bottom caisson 3 is connected to the air pressure regulation system for local buoyancy adjustment and attitude control.

[0038] In this embodiment, multiple independent secondary open-bottom caissons 3 are set inside the primary open-bottom caisson 1 or in the key area of ​​the platform. Each secondary open-bottom caisson 3 is an independent gas-liquid chamber and is connected to the air pressure regulation system.

[0039] The secondary open-bottom caisson 3 can be set at the corner, edge area or bottom support area of ​​the platform for local buoyancy adjustment and attitude control.

[0040] By adjusting the air pressure inside different secondary open-bottom caissons 3, the platform's lateral or longitudinal tilt attitude can be corrected.

[0041] In this embodiment, the air pressure regulation system includes an air source device, an air storage unit, a control valve group, and a piping system. When the platform is idle, a low-power air compressor or vacuum pump can use non-operation time to inflate or evacuate the air storage tank to store energy, so as to provide rapid buoyancy adjustment capability during operation.

[0042] The air source device can be an air compressor, vacuum pump, air tank or external air source system, and the air pressure regulation system can be arranged on the platform body, auxiliary work vessel or shore-based equipment.

[0043] In this embodiment, a positioning constraint system 4 is set around the platform to limit the horizontal displacement of the platform and provide attitude constraints.

[0044] Positioning constraint system 4 may include:

[0045] Positioning pile structure;

[0046] Guide frame structure;

[0047] Guide rail structure;

[0048] Mooring structure;

[0049] Lateral limiting structure.

[0050] The positioning restraint system 4 can be a fixed or detachable structure and can be used in conjunction with shore-based structures or underwater foundations.

[0051] This embodiment includes the following working processes: diving process, bottoming and leveling process, buoyancy operation process, unloading and diving process, platform departure process, and standby berthing process, with each stage forming a cyclical operation mode.

[0052] 1. Descent process

[0053] When the platform needs to enter maintenance mode, the gas inside the first and second open-bottom caissons is gradually discharged through the air pressure regulation system, causing the water level inside the caissons to rise and the overall buoyancy of the platform to decrease, thereby enabling the platform to slowly submerge.

[0054] During the descent, the buoyancy of each area is kept balanced by adjusting the air pressure inside each of the secondary open-bottom caissons 3, thus preventing the platform from tilting laterally or longitudinally.

[0055] Meanwhile, the air cushion flow stabilization structure 2, which is installed inside the first-stage open-bottom caisson 1, moves upward with the change of liquid level inside the caisson, dividing the internal space of the caisson into multiple air cushion areas, thereby suppressing free liquid surface fluctuations and reducing attitude disturbances during the diving process.

[0056] When the platform approaches the predetermined working depth, reduce the exhaust speed of the first-stage bottom-opening caisson 1 to allow the platform to enter the working position at a lower speed and avoid bottom impact.

[0057] 2. Bottom-out leveling process

[0058] When the platform approaches the riverbed or the operating height, the platform's attitude is finely adjusted by regulating the internal air pressure of each secondary open-bottom caisson 3, so that the platform remains horizontal or at the predetermined angle.

[0059] If necessary, air can be added to local areas to increase local buoyancy, thereby correcting the platform's tilt or pitch error.

[0060] The positioning constraint system 4 also restricts the horizontal displacement of the platform to prevent the platform from shifting under the influence of water flow or external disturbances, thereby ensuring that the platform enters a stable operating state.

[0061] 3. Floating operation process

[0062] Once the platform's attitude has been adjusted, the vessel to be repaired will drive onto the platform and be positioned and secured.

[0063] Subsequently, by replenishing gas into the first-stage open-bottom caisson 1, the overall buoyancy of the platform is increased, and the platform slowly rises, thereby providing local buoyancy support for the underwater part of the repair vessel.

[0064] During the buoyancy lifting process, the air pressure of each secondary open-bottom caisson is adjusted to change the buoyancy distribution in different areas, so that the lifted vessel can maintain a stable attitude.

[0065] The air cushion flow stabilization structure 2 continuously suppresses water fluctuations inside the caisson during the buoyancy process, thereby improving buoyancy stability.

[0066] 4. Unloading and descent process

[0067] After the maintenance work is completed, the gas inside the first-stage open-bottom caisson 1 is gradually discharged through the air pressure regulation system, which reduces the overall buoyancy of the platform and causes the platform to slowly submerge, thereby allowing the towed vessel to gradually return to the water.

[0068] During the unloading process, the buoyancy of each area is adjusted by the two-stage open-bottom caisson 3 to prevent the ship from tilting or experiencing localized impacts.

[0069] Once the repair vessel is completely detached from the platform support, the platform continues to descend to a safe clearance height, allowing the repair vessel to safely leave the platform area.

[0070] 5. Platform Exit Process

[0071] After the maintenance vessel departs, the platform is raised to a floating state by replenishing air into the first-level open-bottom caisson 1.

[0072] During the ascent, the air pressure of the secondary open-bottom caisson 3 is adjusted to maintain the platform's stable posture.

[0073] Once the platform reaches the required draft for relocation, the positioning constraint system 4 is released, and the platform can be moved to other work areas or standby areas by towing, pushing, or self-propelled means.

[0074] 6. Standby parking process

[0075] When not in operation, the platform can be moored in shallow water or at a pre-set berth.

[0076] In standby mode, the platform can adopt two modes: floating standby or bottoming standby.

[0077] In floating standby mode, the platform remains in an inflated floating state and is fixed in position by mooring or positioning stakes so as to quickly enter the working state.

[0078] In the bottoming standby mode, the platform slowly descends and lands on the bottom by venting, and is stabilized by the positioning restraint system 4, the platform's own weight, and bottom contact, thereby reducing drift and wave effects.

[0079] When operations are required again, the platform is brought back to the surface and ready for operation by replenishing air to the first-level open-bottom caisson 1.

[0080] 7. Cyclic operation process

[0081] The complete workflow of this invention platform is as follows:

[0082] Submerge → Leveling → Float → Unload and Submerge → Ascend and Depart → Moor and Standby → Resuming Operations

[0083] Through the above-described cyclical process, continuous operation and mobile deployment of the submersible vessel maintenance platform can be achieved.

[0084] The working principle of this invention is based on gas-liquid coupling for flow stabilization and negative pressure leveling.

[0085] In an open-bottom caisson structure, the gas inside the caisson and the external water form a gas-liquid coupling system through the gas-water interface. By adjusting the gas pressure inside the caisson, the height of the gas-water interface can be changed, thereby altering the caisson's drainage volume and achieving buoyancy adjustment.

[0086] When the caisson is under positive pressure, the gas pressure acts on the gas-water interface, causing the water level inside the caisson to drop, the drainage volume to increase, and the buoyancy of the platform to increase, thus enabling the platform to float. When the gas inside the caisson is discharged, the water level inside the caisson rises, the drainage volume to decrease, and the buoyancy of the platform to decrease, thus enabling the platform to submerge.

[0087] The gas and liquid flows inside the caisson satisfy the gas-liquid two-phase coupling condition, and the interfacial flow can be described by the Navier-Stokes equations:

[0088]

[0089] in:

[0090] For fluid density;

[0091] v is the fluid velocity vector;

[0092] p represents pressure;

[0093] Dynamic viscosity;

[0094] g is the acceleration due to gravity.

[0095] In an open-bottom caisson system, changes in gas pressure create a pressure gradient term. This drives the movement of the air-water interface; the liquid inertia term reflects the mass inertia of the water; the viscosity term dampens the fluctuations of the liquid surface. By controlling the rate of change of air pressure inside the caisson, the pressure gradient can be adjusted, thereby suppressing liquid surface oscillations and improving system stability.

[0096] When an air cushion layer forms inside the caisson, the compressibility of the gas gives the system the characteristics of an air spring. The gas compression process can be approximated by the gas law:

[0097]

[0098] The compressibility of the gas provides restoring force, and the mass of the liquid provides inertia. Together, they constitute a gas-liquid coupled vibration system, which suppresses water fluctuations inside the caisson.

[0099] When a slight negative pressure is created inside the caisson, the external water pressure is greater than the gas pressure inside the caisson, and the air-water interface reaches a stable equilibrium under the influence of the pressure difference. At this time, the water column inside the caisson can maintain a stable suspended state for a short period of time under the combined action of air pressure and water pressure, thereby enabling fine-tuning of the platform's attitude.

[0100] As the negative pressure inside the caisson increases further, the stability of the gas-liquid system decreases. This is due to the pressure gradient term. Increased pressure leads to increased velocity at the air-water interface, intensified surface oscillations, and potentially nonlinear fluctuations and localized tumbling. Simultaneously, external water accelerates into the caisson under significant pressure differential, causing rapid changes in liquid level and consequently, fluctuations in platform attitude.

[0101] Furthermore, under high negative pressure, the caisson structure bears external pressure loads, and the top and sidewall structures of the caisson are subjected to compressive stress. When the negative pressure exceeds the structural design value, local buckling or structural deformation may occur. If a floating flow stabilizing structure is installed inside the caisson, a large negative pressure may also cause the floating structure to be subject to adsorption, affecting its free floating ability and thus reducing the flow stabilizing effect.

[0102] Therefore, in a multi-stage caisson structure, the air pressure regulation system is preferably set with a negative pressure control range. By limiting the negative pressure amplitude through compartmentalized pressure regulation and gradual air replenishment, the system can be kept operating within a stable gas-liquid coupling range, thereby improving the platform's leveling stability and reducing structural risks.

[0103] By adjusting the pressure distribution inside different caissons, a multi-degree-of-freedom gas-liquid coupling system can be formed, enabling overall buoyancy adjustment and attitude stability control of the platform. Even without a float structure, the caisson system can still rely on gas compressibility and liquid inertia to form a stable fluid system, thereby maintaining good fluid stability and leveling capability.

[0104] Summary of working principles:

[0105] The first-stage open-bottom caisson 1 provides overall buoyancy adjustment capability;

[0106] Multiple two-stage open-bottom caissons provide attitude leveling capability;

[0107] Air cushion flow stabilization structure 2 suppresses fluctuations in the liquid level inside the caisson;

[0108] The air pressure regulation system enables compartment pressure control;

[0109] Positioning constraint system 4 restricts the lateral displacement of the platform;

[0110] The multi-stage caisson gas-liquid coupling system achieves stable leveling capability under the hydrodynamic conditions described by the Navier-Stokes equations and realizes attitude fine-tuning within the negative pressure control range, thereby ensuring the stable operation of the submersible vessel maintenance platform.

Claims

1. A multi-stage air-cushion open-bottom caisson submersible ship repair platform, characterized in that, include: At least one primary open-bottom caisson, which is used to provide overall buoyancy and is connected to the external water body to form an open-bottom structure; The partitioned air cushion flow stabilization structure installed inside the primary open-bottom caisson and / or the secondary caisson is used to divide the free liquid surface inside the caisson into multiple restricted areas and suppress liquid surface fluctuations through controlled flow damping. Multiple independent two-stage open-bottom caissons, which are used for local buoyancy adjustment; The air pressure regulation system is used to regulate the air pressure inside each caisson; A positioning constraint system, wherein the positioning constraint system is used to limit the spatial displacement of the platform; in: The partitioned air cushion flow stabilization structure includes multiple floating units and restricts lateral displacement through a guide structure, so that the gas-liquid coupling system inside the caisson is transformed from a continuous free liquid surface to a partitioned controlled liquid surface system, thereby achieving stable control of the large-scale open-bottom air cushion system. The partitioned air cushion flow stabilization structure forms multiple air cushion areas inside the caisson and restricts water flow through throttling channels between adjacent areas, thereby reducing the amplitude of liquid surface oscillation.

2. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The primary or secondary open-bottom caisson is equipped with an air cushion flow stabilization structure to suppress free liquid surface fluctuations inside the caisson and form a gas buffer layer. Without the air cushion flow stabilization structure, the free liquid surface inside the open-bottom caisson exhibits large-scale coupled oscillations, making it difficult to achieve stable buoyancy control. By using a zoned flow stabilization structure to discretize the continuous free liquid surface, the system is transformed from an unstable state to a controllable stable state.

3. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 2, characterized in that: The air cushion flow stabilizing structure is a floating structure and can move up and down with the change of liquid level in the caisson.

4. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 2, characterized in that: The air cushion stabilization structure is one or more of the following: a floating plate structure, a floating box structure, a porous floating plate structure, or a combined floating structure.

5. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: Multiple secondary open-bottom caissons are arranged inside the primary open-bottom caisson, at the corners of the platform, at the edge areas, or in key leveling areas.

6. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The secondary open-bottom caisson is used to adjust the platform's lateral tilt, longitudinal tilt, or partial buoyancy.

7. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The air pressure regulation system includes one or more of the following: an air compressor, a vacuum pump, an air tank, a control valve assembly, and gas pipelines.

8. The multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The positioning constraint system includes one or more of the following: positioning stakes, guide frames, guide rails, mooring structures, lateral limiting structures, or equivalent constraint structures.

9. A multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The caisson is an open-bottom structure that is closed at the top and sides and connected to the external water body at the bottom.

10. A multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The multi-stage caissons form a multi-degree-of-freedom buoyancy adjustment system through compartmentalized air pressure regulation, which is used to achieve platform heave control and attitude stability control.

11. A multi-stage air-cushion open-bottom caisson submersible ship repair platform according to claim 1, characterized in that: The air pressure regulation system includes an energy storage unit for storing air pressure energy in non-operational states and releasing it during operation to achieve rapid buoyancy adjustment of the caisson.

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