An offshore fixed pile foundation adaptive ice resistant structure

Abstract

The application discloses a kind of offshore fixed pile foundation self-adapting ice-resistant structure, including the ice-resistant foundation body of being set in the periphery of pile foundation, it is composed of floating sleeve, positive and negative cone combination icebreaking cone and passive guide limiting mechanism.Floating sleeve is equipped with buoyancy tank and fills low-density buoyancy material to realize automatic lifting with water level;Its outer periphery is fixed with upper cone and lower cone connected symmetrically to form positive and negative cone combination structure, for bidirectional guiding sea ice bending damage.Passive guide limiting mechanism includes vertical guide rail arranged on the outer wall of pile foundation, guide block arranged on the inner wall of floating sleeve and limiting ring plate arranged on the top and bottom of guide rail, sliding block and guide rail are slidingly connected to guide lifting, limiting ring plate limits lifting range.Floating sleeve is connected into split structure by two semicircular cylinder flanges.No external power is needed, can adapt to water level change, realize bidirectional icebreaking, guide limiting, extreme stop and convenient maintenance, and can be widely applied to ice area offshore photovoltaic and offshore wind farm.

Description

Technical Field

[0001] This invention belongs to the field of basic marine engineering technology, specifically relating to an adaptive anti-icing structure suitable for offshore fixed pile foundations in cold sea areas, especially suitable for the infrastructure of offshore photovoltaic fields and offshore wind farms in sea areas with large tidal ranges. Background Technology

[0002] With the increasing global demand for renewable energy, the offshore energy industry in cold regions is developing rapidly. However, sea ice hazards are a core issue threatening the safe service of offshore fixed pile foundation structures. Currently, the ice-resistant design of pile foundations in ice-covered areas has the following significant shortcomings.

[0003] Inappropriate ice load failure mode: When sea ice interacts with pile foundations, the continuous impact of sea ice loads, ice-induced vibrations, and fatigue effects will have a huge impact on the pile foundations. Although traditional ice-resistant cones can guide ice floes to bend and fail, some broken ice can easily climb up the cone, overturn, and fall to the edge of the cone, causing accumulation. This accumulation phenomenon will change the guidance of bending failure of the ice floes, causing the ice floes to undergo compression failure in front of the cone. Since the compression strength of sea ice is much higher than its bending strength, it leads to a surge in structural stress.

[0004] The adaptability to water level changes is extremely poor: tidal changes cause drastic fluctuations in water level, making it difficult for existing anti-ice devices to always be in the optimal ice-breaking position. While some solutions for liftable anti-ice devices exist, they all have significant drawbacks. Existing fixed multi-stage cone solutions, although adapting to different tide levels by using multiple cone shells, have fixed cone positions that cannot continuously change with water level, limiting ice-breaking efficiency to the number and spacing of the preset cones. Active lifting solutions (such as hydraulic self-lifting systems, rack and pinion drives, and electric drives) are complex and costly, and rack and pinion mechanisms are susceptible to jamming due to broken ice. Electric drive solutions require external power and have poor reliability in harsh icy environments. While self-floating anti-ice solutions propose the core concept of using buoyancy for lifting, they use annular airbags as position locking devices, requiring an inflation unit and control system, resulting in a complex structure and active control. Furthermore, they do not specify the concrete configuration of the anti-ice cone or provide a technical solution to ensure the cone maintains the correct ice-facing direction during lifting.

[0005] Therefore, there is an urgent need to develop a new type of anti-ice structure that is simple in structure, requires no external power drive, requires no active control system, can reliably adapt to water level changes, and always maintains the correct ice-facing direction. Summary of the Invention

[0006] The purpose of this invention is to provide an adaptive anti-icing structure for offshore fixed pile foundations. Through the organic coordination of five components—a floating sleeve, a positive and negative cone, a guide rail, a limiting ring plate, and a split structure—it overcomes the shortcomings of existing anti-icing devices, such as their inability to adapt to changes in water level, the tendency for ice fragments to accumulate, and the complex and unreliable structure of active lifting schemes. It achieves comprehensive technical effects, including adaptive lifting without external power, bidirectional ice-breaking guidance, circumferential limiting and anti-torsion, stopping under extreme working conditions, and convenient maintenance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an adaptive ice-resistant structure for offshore fixed pile foundation, comprising an ice-resistant foundation body sleeved around the pile foundation, wherein the ice-resistant foundation body is composed of a floating sleeve, a combination of positive and negative cone ice-breaking cones and a passive guiding and limiting mechanism; The floating sleeve is a cylindrical structure, concentrically fitted on the outside of the pile foundation. The interior of the floating sleeve has a sealed cavity to form a buoyancy chamber, which is filled with a buoyancy material with a density less than seawater, so that the ice-resistant foundation body can automatically rise and fall with the water level. The combined positive and negative cone ice-breaking cone is fixedly installed on the outer peripheral wall of the floating sleeve, including an upper cone and a lower cone arranged symmetrically. Both the upper cone and the lower cone are truncated cone structures. The small end of the upper cone faces upward and the large end faces downward, while the small end of the lower cone faces downward and the large end faces upward. The large ends of the upper cone and the lower cone are connected to form a combined positive and negative cone structure. The passive guiding and limiting mechanism includes several vertical guide rails set on the outer wall of the pile foundation, several guide sliders set on the inner wall of the floating sleeve, and limiting ring plates set on the top and bottom of the guide rails. The guide sliders slide in cooperation with the guide rails, so that the floating sleeve can rise and fall along the axial direction of the pile foundation. The limiting ring plates are used to limit the rising and falling range of the floating sleeve. The floating sleeve consists of two semi-circular cylinders connected by flanges to form a split structure.

[0008] Furthermore, the inner diameter of the floating sleeve is larger than the outer diameter of the pile foundation, creating an annular gap between the floating sleeve and the pile foundation; the buoyancy chamber is enclosed by the wall of the floating sleeve, and the buoyancy material is foam glass, polyurethane foam, or composite polymer foam material; the overall density of the entire floating sleeve and the combined positive and negative cone icebreaker is less than the density of seawater; or In deep water or in situations requiring greater buoyancy, the buoyancy chamber is replaced by a sealed cavity structure instead of the buoyancy material, using air to provide buoyancy. The buoyancy chamber is equipped with a partition and a one-way pressure relief valve, and is supplemented by an inflation and adjustment system to achieve active and precise control of buoyancy.

[0009] Furthermore, the angle between the conical surfaces of the upper cone and the lower cone and the horizontal plane is 30° to 60°.

[0010] Furthermore, the surface of the combined positive and negative cone ice-breaking cone is provided with a wear-resistant and corrosion-resistant coating, and is provided with a number of ice-breaking teeth, which are spaced apart along the generatrix of the cone; the ice-breaking teeth are triangular teeth, trapezoidal teeth, sawtooth teeth, or teeth arranged in a spiral along the generatrix of the cone.

[0011] Furthermore, the guide rails are evenly arranged along the circumference of the pile foundation, and the length of the guide rails extends from below the design low water level to above the design high water level, so as to ensure that the floating sleeve can maintain guidance throughout the entire range of tidal changes.

[0012] Furthermore, the limiting ring plate is welded to the top and bottom of the guide rail, and the limiting ring plate, the guide rail and the guide slider together constitute the lifting boundary constraint system of the floating sleeve.

[0013] Furthermore, a friction-reducing pad is provided between the guide slider and the guide rail; or For pile foundations with smaller diameters or lighter loads, the passive guide and limit mechanism uses a groove-roller structure instead of a guide rail-slider structure. That is, an annular groove is set on the outer wall of the pile foundation, and several sets of rollers are set on the inner wall of the floating sleeve. The rollers slide in the annular groove to achieve axial lifting and circumferential limiting.

[0014] Furthermore, the combined positive and negative cone ice-breaking cone is a two-part structure that can be detached along the generatrix of the cone. The two parts are connected by field bolts through connecting ear plates, which corresponds to the split structure of the floating sleeve, and together realizes the split-type maintainable design of the whole system.

[0015] Furthermore, the pile foundation is a cylindrical pipe pile structure, and the diameter of the pile foundation is either the same or a variable diameter pipe pile.

[0016] Furthermore, in areas with relatively light ice loads or thin ice, the combined positive and negative cone icebreaker is a hollow sandwich structure, filled internally with lightweight high-strength concrete or high-density foam to reduce its weight; or The combined positive and negative cone ice-breaking cone has a cavity inside, which is equipped with a water injection port and a vacuum port. Water is injected and negative pressure is drawn at extreme low temperatures to accelerate the formation of ice layer and enhance the surface hardness and impact resistance of the cone.

[0017] The working process and force mechanism of this invention are as follows: When the tide level changes, the floating sleeve automatically rises and falls with the water level under the buoyancy provided by the buoyancy chamber, without any external power or active control. During this process, the guide slider slides along the guide rail to ensure that the floating sleeve rises and falls smoothly along the axial direction; under the action of horizontal loads such as waves and sea ice, the cooperation between the guide slider and the guide rail restricts the circumferential rotation of the floating sleeve, so that the ice-breaking cone always contacts the ice layer in the correct ice-facing direction; when the sea ice contacts the upper or lower cone of the ice-breaking cone (depending on the relative position of the water level and the ice layer at that time), under the guidance of the cone surface, the sea ice undergoes bending failure rather than compression failure, and the ice fragments slide down along the cone surface without accumulation; under extreme high or low water level conditions, the limiting ring plate acts as a mechanical stop to prevent the floating sleeve from falling off the guide rail, ensuring safety; when the ice-breaking cone is worn, the split floating sleeve and the split ice-breaking cone can be disassembled outside the pile foundation, the worn parts can be replaced and reassembled without affecting the main structure of the pile foundation.

[0018] The beneficial effects of this invention are: (1) Excellent water level adaptability: The buoyancy chamber design enables the anti-icing device to automatically follow water level fluctuations without manual adjustment or mechanical drive. Its effective working water level coverage is 100% larger than that of the fixed structure, making it suitable for ice-covered sea areas with large tidal ranges, such as the Bohai Sea and similar cold regions.

[0019] (2) Optimization of structural reliability and economy: The cooperation between the guide rail and the slider greatly reduces the frictional resistance between the floating sleeve and the pile foundation, and reduces the wear of moving parts. At the same time, the structure does not change the original pile foundation and is suitable for various pile types (steel pipe piles, PHC piles, precast high-strength concrete thin-walled steel pipe piles, etc.). It is applicable to both new construction and renovation, and the overall construction cost is reduced by about 15% compared with traditional underwater fixed anti-icing devices.

[0020] (3) Extended service life: By avoiding ice floe compression damage and ice fragment accumulation, ice-induced vibration and fatigue effects are greatly reduced. It is estimated that this structure can reduce the fatigue damage accumulation rate of pile foundations during ice periods by more than 50%, significantly extending the service life of offshore fixed pile foundation structures.

[0021] (4) Significantly improved ice-breaking effect: The combination of positive and negative cones ensures that ice floes can be guided to bend and break at any water level. According to the mechanical properties of ice, the load required for bending failure is only about 1 / 3 of that required for compression failure, which can greatly reduce the impact of ice load on the pile foundation. According to simulation calculations, the peak load is reduced by about 30% to 40% compared with the traditional straight pile structure. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the offshore fixed pile foundation anti-icing structure of the present invention; Figure 2This is a cross-sectional view of the ice-breaking structure; Figure 3 This is a schematic diagram of the guiding mechanism of the present invention; Figure 4 This is a schematic diagram of the arrangement of ice-breaking teeth on the surface of the ice-breaking cone of the present invention.

[0023] In the diagram, 1—pile foundation; 2—floating sleeve; 3—ice-breaking cone; 3-1—upper cone; 3-2—lower cone; 3-3—connecting ear plate; 4—guide mechanism; 4-1—guide rail; 4-2—guide slider; 5—limiting ring plate; 6—ice-breaking teeth. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] In the description of this invention, it should be noted that the terms "upper", "middle", "lower", "inner", "outer", "both sides", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] like Figure 1-4 As shown, the adaptive anti-icing structure of the offshore fixed pile foundation of the present invention includes an anti-icing foundation body sleeved around the pile foundation 1. The anti-icing foundation body is composed of a floating sleeve 2, a positive and negative cone combined ice-breaking cone 3 and a passive guide and limiting mechanism.

[0028] The floating sleeve 2 is a cylindrical structure, concentrically fitted outside the pile foundation 1. The interior of the floating sleeve 2 is provided with a sealed cavity to form a buoyancy chamber. The buoyancy chamber is filled with a buoyancy material with a density less than seawater, so that the ice-resistant foundation body can automatically rise and fall with the water level.

[0029] The combined ice-breaking cone 3 is fixedly installed on the outer peripheral wall of the floating sleeve 2, and includes an upper cone 3-1 and a lower cone 3-2 arranged symmetrically. Both the upper cone 3-1 and the lower cone 3-2 are truncated cone structures. The small end of the upper cone 3-1 faces upward and the large end faces downward, while the small end of the lower cone 3-2 faces downward and the large end faces upward. The large ends of the upper cone 3-1 and the lower cone 3-2 are connected to form a combined ice-breaking cone structure.

[0030] The passive guiding and limiting mechanism includes several vertical guide rails 4-1 disposed on the outer wall of the pile foundation 1, several guide sliders 4-2 disposed on the inner wall of the floating sleeve 2, and limiting ring plates 5 disposed on the top and bottom of the guide rails 4-1. The guide sliders 4-2 slide in cooperation with the guide rails 4-1, so that the floating sleeve 2 can rise and fall along the axial direction of the pile foundation 1. The limiting ring plates 5 are used to limit the rising and falling range of the floating sleeve 2.

[0031] The floating sleeve 2 is a split structure consisting of two semi-circular cylinders connected by flanges.

[0032] The anti-ice structure of this invention is fitted onto the sea ice activity area of ​​a fixed pile foundation at sea. When the tide level changes, the floating sleeve 2 automatically rises and falls with the water level under the buoyancy provided by the buoyancy material in the buoyancy chamber, without any external power or active control system drive. During this process, the guide slider 4-2 slides along the guide rail 4-1 to ensure that the floating sleeve 2 rises and falls smoothly along the axial direction of the pile foundation 1. Under the action of horizontal loads such as waves and sea ice, the cooperation between the guide slider 4-2 and the guide rail 4-1 restricts the circumferential rotation of the floating sleeve 2, so that the combined positive and negative cone icebreaker 3 always contacts the ice layer in the correct ice-facing direction. After the sea ice contacts the upper cone 3-1 or lower cone 3-2 of the combined positive and negative cone icebreaker 3 (depending on the relative position of the water level and the ice layer at that time), the sea ice is bent and broken rather than crushed under the guidance of the cone surface, and the ice fragments slide down along the cone surface without accumulating. Under extreme high or low water level conditions, the limiting ring plate 5 acts as a mechanical stop to prevent the floating sleeve 2 from falling off the guide rail 4-1, ensuring safety.

[0033] The adaptive lifting and lowering of the floating sleeve 2, combined with the bidirectional ice-breaking capability of the combined positive and negative cone ice-breaking cone 3, ensures that the ice-breaking function is not limited by tidal fluctuations. Regardless of water level changes, one cone always contacts the ice layer at the optimal angle, effectively covering the entire tidal range. Simultaneously, the guide rail 4-1 and guide slider 4-2 ensure directional stability during lifting and lowering, while the limiting ring plate 5 ensures boundary safety of the lifting range, preventing the floating sleeve 2 from circumferentially deflecting (ensuring the ice-breaking cone's ice-facing direction) and from derailing (ensuring safety under extreme conditions). The split-type structural design allows the entire system to be assembled and disassembled on-site outside the pile foundation 1, eliminating the need to insert it from the pile top and solving the post-installation problem of in-service pile foundations.

[0034] Furthermore, the inner diameter of the floating sleeve 2 is larger than the outer diameter of the pile foundation 1, so that an annular gap is formed between the floating sleeve 2 and the pile foundation 1; the buoyancy chamber is surrounded by the cylinder wall of the floating sleeve 2, and the buoyancy material is foam glass, polyurethane foam or composite polymer foam material; the overall density of the entire floating sleeve 2 and the combined positive and negative cone icebreaker 3 is less than the density of seawater.

[0035] Alternatively, in deep water or in situations requiring greater buoyancy, the buoyancy chamber can be replaced by a sealed cavity structure instead of the buoyancy material, using air to provide buoyancy. The buoyancy chamber is equipped with a partition and a one-way pressure relief valve, and is supplemented by an inflation and adjustment system to achieve active and precise control of buoyancy.

[0036] The annular gap formed between the floating sleeve 2 and the pile foundation 1 avoids direct contact and frictional jamming, ensuring smooth raising and lowering of the floating sleeve 2. The buoyancy chamber is enclosed by a cylindrical wall and filled with low-density buoyancy material (foam glass, polyurethane foam, or composite polymer foam), making the overall density of the device less than that of seawater, thus obtaining sufficient reserve buoyancy to follow water level changes. As an alternative, in deep water or under conditions requiring greater buoyancy, the buoyancy chamber can adopt a closed cavity structure, utilizing air to provide buoyancy. Baffles divide the buoyancy chamber into several independent closed chambers; even if individual chambers are damaged, the overall buoyancy remains unaffected. One-way pressure relief valves automatically release pressure when the chamber pressure is too high, preventing the chamber from bursting. The inflation and regulation system can actively adjust the buoyancy as needed, achieving active and precise control of buoyancy.

[0037] The annular gap design effectively reduces the frictional resistance between the floating sleeve 2 and the pile foundation 1, ensuring the device's responsiveness to water level changes. The selection of low-density buoyancy material allows the device to achieve adaptive lifting and lowering without any external power. The sealed cavity alternative provides a wider buoyancy adjustment range, while the baffles and one-way pressure relief valves significantly improve the safety and reliability of the buoyancy chamber. The inflation adjustment system transforms buoyancy control from passive to active and controllable, making it suitable for complex working conditions such as deep water areas.

[0038] Furthermore, the angle between the conical surfaces of the upper cone 3-1 and the lower cone 3-2 and the horizontal plane is 30° to 60°.

[0039] The angle between the conical surfaces of the upper cone 3-1 and the lower cone 3-2 and the horizontal plane is set to 30°–60°. When sea ice contacts the conical surfaces, the ice floe undergoes bending failure under the guidance of the conical surfaces. According to the ice mechanics properties, the ratio of the vertical to horizontal components of the force exerted by the conical surfaces on the sea ice is optimal within this angle range, effectively inducing the ice floe to bend and fracture at the root of the conical surfaces. The angle range of 30°–60° ensures that the sea ice can reliably undergo bending failure rather than compression failure on the conical surfaces. The load required for bending failure is only 1 / 3 to 1 / 5 of that required for compression failure, which can significantly reduce the impact force of ice load on pile foundation 1, avoid damage to pile foundation 1 caused by ice-induced vibration and fatigue effects, and also avoid the accumulation of ice fragments at the edge of the cones.

[0040] Furthermore, the surface of the combined positive and negative cone icebreaker 3 is provided with a wear-resistant and corrosion-resistant coating, and is provided with a number of icebreaker teeth 6, which are spaced apart along the generatrix of the cone; the icebreaker teeth 6 are triangular teeth, trapezoidal teeth, sawtooth teeth, or teeth arranged in a spiral along the generatrix of the cone.

[0041] A wear-resistant and corrosion-resistant coating covers the surface of the combined positive and negative cone icebreaker 3, resisting seawater corrosion and ice floe abrasion. Icebreaking teeth 6 are spaced apart along the generatrix of the cone. When sea ice slides along the cone surface, the icebreaking teeth 6 generate concentrated stress on the ice layer, forming scratches and cracks on the ice surface, promoting premature ice breakage at the root of the cone. The serrated or spiral arrangement of the icebreaking teeth 6 generates additional splitting action during ice breaking, further improving icebreaking efficiency. The wear-resistant and corrosion-resistant coating significantly extends the service life of the combined positive and negative cone icebreaker 3 in harsh ice-covered environments. The arrangement of the icebreaking teeth 6 changes the contact between the cone surface and the ice layer from surface contact to point / line contact, increasing local contact stress and making the ice layer more prone to breakage, thus improving icebreaking efficiency. The serrated or spiral arrangement of the icebreaking teeth 6 provides stronger breaking capability for thicker ice layers, effectively expanding the applicability of the device.

[0042] Furthermore, the guide rail 4-1 is uniformly arranged around the pile foundation 1, and the length of the guide rail 4-1 extends from below the design low water level to above the design high water level to ensure that the floating sleeve 2 can maintain guidance throughout the entire range of tidal changes.

[0043] Guide rails 4-1 are evenly distributed around the circumference of pile foundation 1, and guide sliders 4-2 are correspondingly installed on the inner wall of floating sleeve 2, with the two slidingly engaged. The upper and lower ends of guide rails 4-1 extend above the design high water level and below the design low water level, respectively, ensuring that floating sleeve 2 is constrained by guide rails 4-1 throughout the entire tidal range. The evenly distributed circumferential guide rails 4-1 ensure balanced force on floating sleeve 2 during lifting and lowering, preventing skewing and jamming. The length of guide rails 4-1 covers the entire range from the design high water level to the design low water level, ensuring that floating sleeve 2 maintains correct guidance at any water level, allowing the ice-breaking cone to always face the ice at the designed angle, fully utilizing its bending ice-breaking function.

[0044] Furthermore, the limiting ring plate 5 is welded to the top and bottom of the guide rail 4-1, and the limiting ring plate 5, the guide rail 4-1 and the guide slider 4-2 together constitute the lifting boundary constraint system of the floating sleeve 2.

[0045] The limiting ring plate 5 is fixedly installed at the top and bottom of the guide rail 4-1. When the floating sleeve 2 rises with the water level to above the design high water level, the upper end face of the guide slider 4-2 abuts against the top limiting ring plate 5, preventing the floating sleeve 2 from rising further; when the floating sleeve 2 falls with the water level to below the design low water level, the lower end face of the guide slider 4-2 abuts against the bottom limiting ring plate 5, preventing the floating sleeve 2 from falling further. As a purely mechanical stop structure, the limiting ring plate 5 reliably limits the lifting range of the floating sleeve 2 under extreme high or low water level conditions, preventing it from detaching from the guide rail 4-1. The limiting ring plate 5, the guide rail 4-1, and the guide slider 4-2 work together to simultaneously achieve three functions: axial lifting guidance, circumferential limiting and anti-torsion, and safety stop under extreme working conditions, forming a complete lifting boundary constraint system.

[0046] Furthermore, a friction-reducing pad is provided between the guide slider 4-2 and the guide rail 4-1. Alternatively, for pile foundation 1 with a smaller diameter or lighter load, the passive guide limiting mechanism adopts a groove-roller structure instead of a guide rail-slider structure. That is, an annular groove is provided on the outer wall of the pile foundation 1, and several sets of rollers are provided on the inner wall of the floating sleeve 2. The rollers slide in the annular groove to achieve axial lifting and circumferential limiting.

[0047] A friction-reducing pad is placed between the contact surfaces of the guide slider 4-2 and the guide rail 4-1, converting the sliding friction between them into low-friction sliding friction, thus reducing lifting resistance. The friction-reducing pad can be made of PTFE (polytetrafluoroethylene), copper alloy, or other low-friction materials. As an alternative, in the groove-roller structure, an annular groove is set on the outer wall of the pile foundation 1 as a guide rail, and a roller is set on the inner wall of the floating sleeve 2 and embedded in the annular groove. When the floating sleeve 2 rises and falls, the roller rolls along the annular groove, converting sliding friction into rolling friction. The friction-reducing pad significantly reduces the frictional resistance between the floating sleeve 2 and the guide rail 4-1, improving the device's response sensitivity to water level changes, while reducing wear on moving parts and extending service life. The groove-roller alternative further converts sliding friction into rolling friction, resulting in lower contact stress and greater wear resistance, making it particularly suitable for pile foundations 1 with smaller diameters or lighter loads.

[0048] Furthermore, the combined positive and negative cone icebreaker 3 is a two-part structure that can be detached along the generatrix of the cone. The two parts are connected by field bolts through connecting ear plates 3-3, which corresponds to the split structure of the floating sleeve 2, and together realize the split-type maintainable design of the whole system.

[0049] The inverted cone combined ice-breaking cone 3 is divided into two semi-conical parts along the generatrix of the cone. Each semi-conical part is pre-assembled and connected to the corresponding semi-circular cylinder of the floating sleeve 2. During on-site installation, the two semi-circular floating sleeves 2 are first joined together around the pile foundation 1 and fixed by flange bolts. Then, the two semi-conical parts are bolted together on-site through connecting ear plates 3-3 to form a complete inverted cone combined ice-breaking cone 3. Disassembly is carried out in the reverse order. The split design of the inverted cone combined ice-breaking cone 3 corresponds to the split structure of the floating sleeve 2, allowing all components of the entire anti-icing structure to be assembled and disassembled on-site around the pile foundation 1. When the ice-breaking cone wears out, the worn parts can be disassembled and replaced and reassembled around the pile foundation 1 without affecting the main structure of the pile foundation 1, greatly reducing maintenance difficulty and cost. At the same time, this invention is applicable to both newly built sites and post-installation modifications in existing sites.

[0050] Furthermore, the pile foundation 1 is a cylindrical pipe pile structure, and the diameter of the pile foundation 1 is either the same or a variable diameter pipe pile.

[0051] The pile foundation 1 adopts a cylindrical pipe pile structure, which can be a steel pipe pile, a PHC pile, or a precast high-strength concrete thin-walled steel pipe pile, etc. The diameter of pile foundation 1 can be set to the same diameter or a variable diameter according to the stress requirements (e.g., increasing the diameter at the mud surface to improve bearing capacity). The inner diameter of the floating sleeve 2 is larger than the maximum outer diameter of pile foundation 1, ensuring the existence of annular gaps. This invention is applicable to various pile types (steel pipe piles, PHC piles, precast high-strength concrete thin-walled steel pipe piles, etc.), and can be well adapted to both pipe piles of the same diameter and those of varying diameters, demonstrating strong versatility. The variable diameter pipe pile design can increase the diameter at the mud surface to improve bearing capacity, while keeping the diameter smaller near the water surface to reduce the area affected by ice loads and optimize structural stress.

[0052] Furthermore, in areas with relatively light ice loads or thin ice, the combined positive and negative cone ice-breaking cone 3 has a hollow sandwich structure, filled with lightweight high-strength concrete or high-density foam to reduce its weight. Alternatively, the combined positive and negative cone ice-breaking cone 3 has an internal cavity with a water injection port and a vacuum port. Water is injected and negative pressure is applied at extreme low temperatures to accelerate ice formation, thereby enhancing the surface hardness and impact resistance of the cone.

[0053] In the hollow sandwich structure, the outer shell of the combined positive and negative cone icebreaker 3 is made of steel plate, while the inner sandwich is filled with lightweight high-strength concrete or high-density foam. This reduces the overall weight while ensuring structural strength and improves the responsiveness to water level changes. In the cavity design, the combined positive and negative cone icebreaker 3 has a sealed cavity inside. Water is injected into the cavity through an injection port, and then negative pressure is created through a vacuum port, forming a negative pressure environment inside the cavity and accelerating the freezing process. Under extreme low-temperature conditions, the water inside the cavity freezes rapidly to form an ice layer. This ice layer bonds tightly to the cone surface, enhancing the surface hardness and impact resistance.

[0054] The hollow sandwich structure effectively reduces the self-weight of the combined positive and negative cone ice-breaking cone 3, enabling the device to respond more sensitively to water level changes in areas with lighter ice loads or thinner ice. The cavity water injection and vacuum pumping scheme utilizes the extreme low temperature environment to form an ice layer inside the cone, significantly enhancing the surface hardness and impact resistance of the cone, making it suitable for harsh working conditions in extremely cold regions.

[0055] This invention utilizes the synergistic effect of five components: a floating sleeve, an ice-breaking cone, a guide rail, a limiting ring plate, and a split structure, which can produce good beneficial results.

[0056] 1. Adaptive icebreaking across the entire water level range The adaptive lifting and lowering of the floating sleeve, combined with the bidirectional ice-breaking capability of the ice-breaking cone structure, works synergistically to ensure that the ice-breaking function is not limited by tidal fluctuations. By filling the buoyancy chamber with a buoyancy material with a density less than seawater, the device rises with the water level, and the lower cone contacts the ice layer; when the water level drops, the device descends with the upper cone, and the upper cone contacts the ice layer. No external power is required, completely solving the failure problem of traditional fixed anti-icing devices caused by water level changes, ensuring that the ice-breaking cone is always within the sea ice activity zone. The result of this synergy is that regardless of water level changes, there is always one cone in contact with the ice layer at the optimal angle, effectively covering the entire tidal range—an effect that neither a single self-floating cone nor a fixed upright / inverted ice-breaking cone can achieve.

[0057] 2. Reliable motion control integrating lifting, guiding, and limiting functions. The self-floating lifting function of the floating sleeve, the axial constraint function of the guide rail, and the end stop function of the limiting ring plate work together to ensure that the floating sleeve maintains controlled movement throughout the entire tidal range and under extreme conditions. The guide rail ensures directional stability during lifting, while the limiting ring plate ensures boundary safety within the lifting range. Their synergy prevents the floating sleeve from circumferentially deflecting (ensuring the ice-breaking cone's ice-facing direction) and from derailing (ensuring safety under extreme conditions). This synergistic effect cannot be achieved by simply adding the functions of the guide rail and the limiting ring plate together—guiding alone cannot prevent derailment, and limiting alone cannot prevent circumferential deflection; only their combined function can simultaneously solve both directional control and displacement boundary control problems.

[0058] 3. System integration design that is maintainable throughout its entire lifecycle. The floating sleeve, ice-breaking cone, guide rail, limiting ring plate, and modular structure together constitute a complete system solution. The components have the following cooperative relationships: Synergy between the floating sleeve and the ice-breaking cone: The ice-breaking cone is fixed to the outer periphery of the floating sleeve and rises and falls synchronously with it, so that the ice-breaking cone is always at the height of the ice layer, ensuring that the bidirectional ice-breaking function of the cone can be exerted in the full water level range; The coordination between the floating sleeve and the guide rail: The guide rail constrains the floating sleeve to move up and down only along the axial direction, so that the ice-breaking cone always maintains the correct ice-facing direction during the lifting and lowering process, avoiding ice-breaking failure due to circumferential rotation; Synergy between the floating sleeve and the limiting ring plate: The limiting ring plate acts as a mechanical stop to prevent the floating sleeve from coming off the guide rail under extreme high / low water level conditions, ensuring safety throughout its entire life cycle; The coordination between the limiting ring plate and the guide mechanism: together they constitute the lifting boundary constraint system of the floating sleeve, which not only ensures smooth lifting under normal working conditions, but also limits the displacement range under extreme working conditions. The synergy between the split-type structural design and the aforementioned four components: Because the floating sleeve and ice-breaking cone are both split-type structures, while the guide rail and limiting ring plate are located on the outer wall of the pile foundation, the complete system composed of these four components can be assembled on-site outside the pile foundation—that is, the guide rail and limiting ring plate are first installed on the outer wall of the pile foundation, and then the split-type floating sleeve (pre-installed with inverted and upright cones) is assembled and installed around the pile foundation. This synergy solves the following technical problem: if the floating sleeve is not a split-type structure, it must be inserted from the top of the pile during the pile foundation construction stage, making it unsuitable for retrofitting existing pile foundations. The synergy between the split-type structure and the floating sleeve, ice-breaking cone, guide rail, and limiting ring plate makes this invention applicable to both newly built and existing sites, an effect that cannot be achieved by the split-type structure alone (without the cooperation of the other four components).

[0059] 4. Multi-mechanism coordinated ice load reduction The ice-breaking mechanism of the ice-breaking cone and the ice-facing direction-maintaining mechanism of the guide rail work together: the ice-breaking cone itself has bidirectional bending ice-breaking capability, but if the cone deflects circumferentially, the contact angle between the cone surface and the ice floe changes, and the bending ice-breaking effect will be greatly reduced. The guide rail ensures that the cone always faces the ice at the designed angle, allowing the bending ice-breaking function of the ice-breaking cone to be fully utilized. The ice load reduction effect produced by the synergy of these two mechanisms is significantly greater than the simple superposition of the individual effects of the ice-breaking cone and the guide rail.

[0060] Example 1 This embodiment takes a certain offshore photovoltaic field in the Bohai Sea as an example. The average annual tidal range in this sea area is about 2.5m, the maximum tidal range is about 3.8m, the ice period is mainly concentrated from December to March of the following year, and the sea ice thickness is generally 10-30cm.

[0061] Pile 1 uses PHC pipe piles with a diameter of 900mm. Floating sleeve 2 has an inner diameter of 1000mm, forming a 50mm annular gap with pile 1. The interior of floating sleeve 2 contains a buoyancy chamber filled with polyurethane foam (density approximately 0.1g / cm³), ensuring that the overall density of floating sleeve 2 and its accessories is less than 1.0g / cm³. Floating sleeve 2 consists of two semi-circular cylinders connected by flanges.

[0062] The ice-breaking cone 3 is made of Q345 low-temperature steel. The angle between the cone surfaces of the upper cone 3-1 and the lower cone 3-2 and the horizontal plane is 45°. Ice-breaking teeth 6 are installed every 200mm along the generatrix of the cone, with a tooth height of 30mm. The surface of the ice-breaking cone 3 is coated with a polyurea wear-resistant and corrosion-resistant coating. The ice-breaking cone 3 is divided into two parts along the generatrix, which are connected in place by bolts to the connecting lugs 3-3.

[0063] Four guide rails 4-1 are evenly arranged around the circumference of pile foundation 1 and are fixed to the outer wall of pile foundation 1 by welding. The length of guide rail 4-1 extends from 0.5m below the design low water level to 0.5m above the design high water level. Guide sliders 4-2 are correspondingly arranged on the inner wall of floating sleeve 2. The slider material is copper alloy, and a PTFE anti-friction pad is placed between the slider and guide rail 4-1. Limiting ring plates 5 are welded to the top and bottom of guide rail 4-1.

[0064] Installation steps: (1) Weld guide rail 4-1 and limiting ring plate 5 to the outer wall of pile foundation 1; (2) Pre-assemble the two parts of the ice-breaking cone 3 with the two semi-circular cylinders of the floating sleeve 2 respectively; (3) Close the two semi-circular floating sleeves 2 around the pile foundation 1 and fix them by connecting and fixing them with flange bolts, while ensuring that the guide slider 4-2 is accurately embedded in the guide rail 4-1; (4) The two parts of the ice-breaking cone 3 are bolted together on site by connecting ear plates 3-3.

[0065] In operation, when the tide rises, the floating sleeve 2 slides upward along the guide rail 4-1 under the action of buoyancy; when the tide falls, it slides downward along the guide rail 4-1 under its own weight. After the sea ice comes into contact with the upper cone 3-1 or the lower cone 3-2 of the icebreaking cone 3, it bends and breaks along the cone surface, and the ice fragments slide down the cone surface without accumulating. Under extreme high or low water level conditions, the limiting ring plate 5 prevents the floating sleeve 2 from detaching.

[0066] In this embodiment, the anti-icing structure of this invention is installed on a pile foundation and compared with a traditional anti-icing structure. To achieve the same icebreaking effect, the traditional anti-icing structure uses 1.5 tons of steel, while the present invention uses only about 1.3 tons, reducing costs by about 15%. Utilizing the buoyancy of the buoyancy chamber, the present invention significantly reduces the fatigue effects caused by wave impact and ice loads under harsh conditions. Based on theoretical deductions and comparative analysis according to marine fatigue design specifications (such as DNV GL), the fatigue performance of the present invention and traditional fixed anti-icing devices differs significantly over their 25-year design service life. According to the Palmgren-Miner linear cumulative theory, due to the significant reduction in stress amplitude and the change in vibration modes, under the same fatigue load and service life, the equivalent cumulative fatigue damage value of the present invention is 0.4, while that of the traditional structure is approximately 0.9, a reduction of more than half. This allows the structure of the present invention to have a large safety margin while fully meeting the 25-year design service life requirement, avoiding the serious fatigue cracking risk faced by traditional structures in the middle of their service life (approximately 10-15 years), and significantly reducing the maintenance costs throughout the entire life cycle.

[0067] Example 2 This embodiment takes an offshore wind farm in a northern sea area as an example. The water depth in this sea area is about 15m, the average annual tidal range is about 1.8m, and the maximum tidal range is about 3.0m.

[0068] Pile 1 uses steel pipe piles with a diameter of 1200mm (variable diameter design, 1500mm at the mud surface). The floating sleeve 2 has an inner diameter of 1300mm, forming a 50mm annular gap with pile 1. The buoyancy chamber is filled with foam glass (density approximately 0.15g / cm³). The icebreaking cone 3 uses a hollow sandwich structure, filled with lightweight high-strength concrete to reduce overall weight.

[0069] Six guide rails 4-1 are evenly arranged around the circumference of pile foundation 1. The length of guide rail 4-1 extends from 0.8m below the design low water level to 0.8m above the design high water level. In addition to being set at the top and bottom of guide rail 4-1, a middle limiting ring plate 5 is also added in the middle of guide rail 4-1 to further restrain the vibration amplitude of floating sleeve 2 under extreme wave conditions.

[0070] In this embodiment, the anti-icing structure of this invention is installed on a pile foundation and compared with a traditional anti-icing structure. To achieve the same ice-breaking effect, the traditional anti-icing structure uses 2 tons of steel, while the present invention uses only about 1.6 tons. Under the same fatigue load and service life, the equivalent cumulative fatigue damage value of the structure of this invention is 0.5, while that of the traditional structure is about 1.2. Overall, the structural cost is reduced by about 20%, and fatigue damage is reduced by more than half.

[0071] The remaining structure and working principle are the same as in Example 1.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A marine fixed pile foundation adaptive ice-resistant structure, characterized in that, It includes an anti-icing foundation body fitted around the pile foundation (1), the anti-icing foundation body being composed of a floating sleeve (2), a positive and negative cone combined ice-breaking cone (3), and a passive guiding and limiting mechanism; The floating sleeve (2) is a cylindrical structure, concentrically fitted outside the pile foundation (1). The interior of the floating sleeve (2) is provided with a sealed cavity to form a buoyancy chamber. The buoyancy chamber is filled with buoyancy material with a density less than seawater, so that the anti-ice foundation body can automatically rise and fall with the water level. The combined ice-breaking cone (3) is fixedly installed on the outer peripheral wall of the floating sleeve (2), including an upper cone (3-1) and a lower cone (3-2) symmetrically arranged. Both the upper cone (3-1) and the lower cone (3-2) are truncated cone structures. The small end of the upper cone (3-1) is upward and the large end is downward, while the small end of the lower cone (3-2) is downward and the large end is upward. The large ends of the upper cone (3-1) and the lower cone (3-2) are connected to form a combined ice-breaking cone structure. The passive guide limiting mechanism includes several vertical guide rails (4-1) set on the outer wall of the pile foundation (1), several guide sliders (4-2) set on the inner wall of the floating sleeve (2), and limiting ring plates (5) set on the top and bottom of the guide rails (4-1). The guide sliders (4-2) slide with the guide rails (4-1) to enable the floating sleeve (2) to rise and fall along the axial direction of the pile foundation (1). The limiting ring plates (5) are used to limit the rising and falling range of the floating sleeve (2). The floating sleeve (2) is a split structure consisting of two semi-circular cylinders connected by flanges.

2. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The inner diameter of the floating sleeve (2) is larger than the outer diameter of the pile foundation (1), forming an annular gap between the floating sleeve (2) and the pile foundation (1); the buoyancy chamber is enclosed by the wall of the floating sleeve (2), and the buoyancy material is foam glass, polyurethane foam, or composite polymer foam material; the overall density of the entire floating sleeve (2) and the combined positive and negative cone icebreaker (3) is less than the density of seawater; or In deep water or in situations requiring greater buoyancy, the buoyancy chamber is replaced by a sealed cavity structure instead of the buoyancy material, using air to provide buoyancy. The buoyancy chamber is equipped with a partition and a one-way pressure relief valve, and is supplemented by an inflation and adjustment system to achieve active and precise control of buoyancy.

3. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The angle between the conical surfaces of the upper cone (3-1) and the lower cone (3-2) and the horizontal plane is 30° to 60°.

4. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The surface of the combined positive and negative cone ice-breaking cone (3) is provided with a wear-resistant and corrosion-resistant coating and a number of ice-breaking teeth (6). The ice-breaking teeth (6) are spaced apart along the generatrix of the cone. The ice-breaking teeth (6) are triangular teeth, trapezoidal teeth, sawtooth teeth or teeth arranged in a spiral along the generatrix of the cone.

5. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The guide rail (4-1) is uniformly arranged around the pile foundation (1). The length of the guide rail (4-1) extends from below the design low water level to above the design high water level to ensure that the floating sleeve (2) can maintain guidance throughout the tidal range.

6. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The limiting ring plate (5) is welded to the top and bottom of the guide rail (4-1). The limiting ring plate (5), the guide rail (4-1), and the guide slider (4-2) together constitute the lifting boundary constraint system of the floating sleeve (2).

7. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, A friction-reducing pad is provided between the guide slider (4-2) and the guide rail (4-1); or For pile foundations (1) with small diameter or light load, the passive guide limiting mechanism adopts a groove-roller structure instead of a guide rail-slider structure. That is, an annular groove is set on the outer wall of the pile foundation (1), and several sets of rollers are set on the inner wall of the floating sleeve (2). The rollers are embedded in the annular groove and slide to achieve axial lifting and circumferential limiting.

8. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The combined positive and negative cone icebreaker cone (3) is a two-part structure that can be detached along the generatrix of the cone. The two parts are connected on-site by connecting ear plates (3-3) with bolts, which corresponds to the split structure of the floating sleeve (2) and together realize the split maintainable design of the whole system.

9. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to claim 1, characterized in that, The pile foundation (1) is a cylindrical pipe pile structure, and the diameter of the pile foundation (1) is the same or is set as a variable diameter pipe pile.

10. The self-adaptive ice-resistant structure for offshore fixed pile foundations according to any one of claims 1 to 9, characterized in that, In areas with relatively light ice loads or thin ice, the combined positive and negative cone ice-breaking cone (3) is a hollow sandwich structure, filled with lightweight high-strength concrete or high-density foam to reduce its weight; or The ice-breaking cone (3) with the inverted cone and the ice-breaking cone is provided with a cavity. The cavity is provided with a water injection port and a vacuum port. Water is injected and negative pressure is drawn at extreme low temperatures to accelerate the formation of ice layer and enhance the surface hardness and impact resistance of the cone.

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