Corrosion-resistant light-weight steel screw pile suitable for complex seabed

Abstract

The invention belongs to the technical field of pile foundation engineering, and provides an anti-corrosion lightweight steel screw pile suitable for a complex seabed, the anti-corrosion lightweight steel screw pile comprises a pile body, the pile body is of a thin-wall circular tube structure, and a structure reinforcing assembly is arranged on the inner wall of the pile body; the spiral blade assembly comprises a guide blade section and a bearing blade section which are sequentially arranged along the outer wall of the pile body from bottom to top, the top of the guide blade section is connected with the bottom of the bearing blade section, and the screw pitch of the guide blade section and the screw pitch of the bearing blade section are sequentially increased from bottom to top. The maximum screw pitch of the guide blade section is smaller than the minimum screw pitch of the bearing blade section, and cutting pieces are arranged on the outer edges of blades of the guide blade section and the bearing blade section and used for damaging the soil body structure on the outer edges of the blades; and the anti-corrosion assembly comprises an electrochemical anti-corrosion layer and a shielding anti-corrosion layer which are sequentially coated on the surfaces of the pile body, the guide blade section and the bearing blade section. Through the collaborative design of the machinable soil body structure and the variable pitch, the resistance moment is effectively reduced, and meanwhile the light weight of the pile body is achieved.

Description

Technical Field

[0001] This invention belongs to the field of pile foundation engineering technology, and in particular relates to a corrosion-resistant and lightweight steel helical pile suitable for complex seabeds. Background Technology

[0002] As a highly efficient foundation type, helical piles have been widely used in marine engineering due to their advantages such as convenient installation, high bearing capacity, and minimal environmental impact. They penetrate the seabed by rotation, primarily relying on the end bearing capacity provided by the helical blades and the side friction of the pile.

[0003] However, in practical engineering applications, especially in complex marine environments, traditional helical piles have revealed the following significant drawbacks: Poor geological adaptability and construction difficulties: Traditional helical piles typically employ a blade design with equal pitch and smooth outer edges. When facing dense sand, hard clay, or complex seabeds with hard interlayers, this design lacks sufficient soil cutting ability, leading to a sharp increase in penetration torque. Furthermore, on extremely soft surface soil or sloping seabeds, insufficient initial engagement may cause "pile slippage," resulting in pile tilting and making it difficult to guarantee verticality and the designed penetration depth.

[0004] Structural redundancy and poor economic efficiency: To cope with complex marine loads (such as waves, currents, ice loads, etc.), traditional designs often rely on simply increasing the thickness of the pile wall and blades to ensure safety. This design results in a large amount of material redundancy, which not only significantly increases the amount of steel used and manufacturing costs, but also greatly increases the self-weight of the pile, bringing additional difficulties and costs to marine transportation, hoisting and construction.

[0005] Insufficient corrosion resistance and questionable durability: The high temperature, high humidity, and high salinity of the marine environment pose a strong corrosive effect on steel structures. Traditional helical piles often employ a single coating or cathodic protection. Under long-term erosion, alternating wet and dry conditions, and biofouling, the anti-corrosion layer is prone to failure, leading to uniform corrosion or localized pitting of the steel substrate. This gradually weakens the effective cross-section, seriously threatening the long-term safety of the structure and resulting in high maintenance costs. Summary of the Invention

[0006] The purpose of this invention is to provide a corrosion-resistant and lightweight steel helical pile suitable for complex seabeds, in order to solve the above-mentioned problems, achieve lightweight structure while ensuring high bearing capacity and excellent corrosion resistance, and significantly improve adaptability and construction friendliness to complex and variable seabed geological conditions.

[0007] To achieve the above objectives, the present invention provides the following solution: a corrosion-resistant, lightweight steel helical pile suitable for complex seabeds, comprising: The pile body is a thin-walled circular tube structure, and structural reinforcement components are provided on the inner wall of the pile body; The helical blade assembly includes a guide blade segment and a load-bearing blade segment arranged sequentially from bottom to top along the outer wall of the pile body. The top of the guide blade segment is connected to the bottom of the load-bearing blade segment. The pitch of the guide blade segment and the pitch of the load-bearing blade segment increase sequentially from bottom to top, and the maximum pitch of the guide blade segment is less than the minimum pitch of the load-bearing blade segment. The outer edges of the guide blade segment and the load-bearing blade segment are provided with cutting elements to destroy the soil structure at the outer edge of the blade. The corrosion protection components include an electrochemical corrosion protection layer and a shielding corrosion protection layer that are sequentially coated on the surfaces of the pile body, the guide blade segment, and the load-bearing blade segment.

[0008] Preferably, the lead angle of the guide vane segment is smaller than that of the carrier vane segment.

[0009] Preferably, an anti-overturning blade segment is fixedly connected to the side wall of the pile body. The anti-overturning blade segment is disposed on top of the bearing blade segment. The outer diameter of the anti-overturning blade segment is larger than the outer diameter of the bearing blade segment. The number of turns of the anti-overturning blade segment is [number]. A guide pile tip is provided at the bottom of the pile body.

[0010] Preferably, the cutting element includes a plurality of serrated grooves formed on the outer edge of the blades of the guide blade segment and the carrier blade segment, and the plurality of serrated grooves are equally spaced.

[0011] Preferably, the electrochemical anti-corrosion layer is a hot-dip galvanized layer, covering the outer surfaces of the pile body, guide blade segment, bearing blade segment and anti-overturning blade segment, and the shielding anti-corrosion layer is a modified epoxy coating, covering the surface of the electrochemical anti-corrosion layer.

[0012] Preferably, the structural reinforcement component includes multiple reinforcing ribs, which are vertically fixed to the inner wall of the pile body.

[0013] Preferably, the guide leaf segment and the carrier leaf segment have multiple through holes on their blade surfaces, and the multiple through holes are evenly distributed.

[0014] Preferably, a cutting edge is provided on the side of the through hole facing the spiral direction of the guide blade segment and the bearing blade segment. The cutting edge is used to cut the soil to reduce the spiraling resistance.

[0015] Preferably, the bottom of the blades of the guide blade segment and the carrier blade segment are fixedly connected with multiple reinforcing plates, which are respectively located on the sides of multiple through holes. The reinforcing plates are arc-shaped and arranged parallel to the rotation direction of the blades of the guide blade segment and the carrier blade segment.

[0016] Preferably, a connecting flange is fixedly connected to the top of the pile body to rigidly connect the pile body to the superstructure.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: 1. This invention optimizes the soil cutting and removal mechanism by combining the cuttable soil structure set on the outer edge of the blade with the variable pitch design, effectively reducing the resistance torque during the pile driving process, enabling the pile foundation to smoothly penetrate hard soil layers and reducing the energy consumption of construction equipment.

[0018] 2. The variable pitch design of this invention enables the upper bearing blades to mobilize a larger range of soil to participate in pull-out resistance, thereby improving the ultimate bearing capacity of a single pile and exhibiting excellent pull-out bearing capacity.

[0019] 3. This invention achieves lightweighting of the pile body without compromising mechanical properties, reducing manufacturing costs and the difficulty of marine transportation. Simultaneously, the composite anti-corrosion system on the outer wall of the helical pile overcomes the shortcomings of a single anti-corrosion layer, significantly improving the corrosion resistance of the pile foundation in a marine environment and extending the maintenance cycle. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the spiral pile of the present invention; Figure 2 This is a top view of the spiral shape of the present invention; Figure 3 This is a cross-sectional schematic diagram of the through hole in the present invention; Figure 4 This is a bottom view of a through hole in the present invention; Among them, 1. pile body; 2. helical blade assembly; 3. connecting flange; 4. guide pile tip; 5. reinforcing rib; 6. electrochemical anti-corrosion layer; 7. shielding anti-corrosion layer; 8. serrated groove; 9. guide blade segment; 10. load-bearing blade segment; 11. through hole; 12. anti-overturning blade segment; 13. reinforcing plate; 14. cutting edge. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Reference Figures 1-4 This invention provides a corrosion-resistant, lightweight steel helical pile suitable for complex seabeds, comprising: Pile body 1 is a thin-walled circular tube structure, and structural reinforcement components are provided on the inner wall of pile body 1. The helical blade assembly 2 includes a guide blade segment 9 and a load-bearing blade segment 10 arranged sequentially from bottom to top along the outer wall of the pile body 1. The top of the guide blade segment 9 is connected to the bottom of the load-bearing blade segment 10. The pitch of the guide blade segment 9 and the pitch of the load-bearing blade segment 10 increase sequentially from bottom to top, and the maximum pitch of the guide blade segment 9 is less than the minimum pitch of the load-bearing blade segment 10. The outer edges of the guide blade segment 9 and the load-bearing blade segment 10 are provided with cutting elements to destroy the soil structure at the outer edge of the blade. The corrosion protection components include an electrochemical corrosion protection layer 6 and a shielding corrosion protection layer 7, which are sequentially coated on the surfaces of the pile body 1, the guide blade segment 9, and the load-bearing blade segment 10.

[0025] The pile body 1 is designed with a thin-walled structure, which effectively reduces the helical mass. The main function of the structural reinforcement components is to improve the structural stiffness of the pile body. The main function of the guide blade segment 9 is to reduce the initial torque and axial pressure requirements when cutting into hard soil layers by setting a smaller gradually changing pitch structure, thus acting as a drill bit. The main function of the bearing blade segment 10 is to increase the soil shear volume between adjacent blades by setting a larger gradually changing pitch structure, allowing more soil to participate in pull-out resistance, thus acting as an anchor. The main function of the cutting component is to act as a cutting tool during the rotation of the helical blades, effectively disrupting the soil structure and further reducing the resistance during insertion, especially suitable for compacted sandy soil or hard clay layers. The main function of the anti-corrosion components is to improve the anti-permeability and adhesion of the coating by setting two anti-corrosion layers, thereby improving the long-term durability and reliability of the helical pile in marine environments. Overall, this invention significantly reduces the construction torque and improves the bearing capacity in complex strata through the design of variable pitch blades and cutting components. It achieves lightweight design by utilizing structural reinforcement components and thin-walled pile structure. At the same time, it greatly extends the service life of helical piles in marine environments by using a composite protection system of electrochemical and dense covering, thus achieving the goals of convenient construction, excellent load-bearing capacity, and economic durability.

[0026] Further optimization of the scheme resulted in the lead angle of guide vane segment 9 being smaller than that of carrier vane segment 10.

[0027] By reducing the lead angle of guide vane segment 9, the initial torque and circumferential pressure requirements for cutting into hard soil layers can be further reduced, while the torque borne by the pile body is also reduced, which is more conducive to the lightweight design of the pile body.

[0028] The scheme is further optimized by fixing an anti-overturning leaf segment 12 to the side wall of the pile body 1. The anti-overturning leaf segment 12 is set on top of the bearing leaf segment 10. The outer diameter of the anti-overturning leaf segment 12 is larger than the outer diameter of the bearing leaf segment 10. The number of turns of the anti-overturning leaf segment 12 is 1. A guide pile tip 4 is provided at the bottom of the pile body 1.

[0029] like Figure 1 As shown, when the helical pile is in place, the anti-overturning leaf segment 12 is located near the mud surface. Through the large contact area, it can effectively mobilize a larger area of ​​soil near the mud surface to generate a resisting moment when the pile body 1 is subjected to a large horizontal load (such as wave force), thereby significantly enhancing the overall anti-overturning stability of the pile foundation.

[0030] A conical guide tip 4 is welded to the bottom of the pile body 1. By setting this guide tip 4, the construction alignment and initial penetration positioning can be facilitated.

[0031] The further optimized scheme includes multiple serrated grooves 8 formed on the outer edge of the blades of the guide vane segment 9 and the carrier vane segment 10, with the multiple serrated grooves 8 being evenly distributed.

[0032] In this embodiment, by opening serrated grooves 8 at equal intervals on the outer edge of the spiral blade, a continuous and sharp serrated structure is formed on the outer edge of the blade. By setting this serrated cutting edge, the dense soil layer or hard shell layer can be cut and broken efficiently like a knife, and the rotational resistance can be significantly reduced.

[0033] The scheme is further optimized. The electrochemical anti-corrosion layer 6 is a hot-dip galvanized layer, which covers the outer surface of the pile body 1, guide blade segment 9, load-bearing blade segment 10 and anti-overturning blade segment 12. The shielding anti-corrosion layer 7 is a modified epoxy coating, which covers the surface of the electrochemical anti-corrosion layer 6.

[0034] In this embodiment, specifically, a hot-dip galvanized layer 6 is used to form an electrochemical anti-corrosion layer 6 at the bottom of the helical pile. The thickness of the hot-dip galvanized layer is ≥85µm. The galvanized layer acts as a sacrificial anode, providing electrochemical protection for the steel substrate of the helical pile and preventing pitting corrosion. On the surface layer, a modified epoxy coating is applied over the galvanized layer to form a shielding anti-corrosion layer 7. This coating is doped with nanoscale fillers, utilizing the dense physical barrier of nanoparticles to extend the penetration path of corrosive media to the substrate, thereby significantly improving the coating's impermeability and adhesion. The synergistic effect of these two layers significantly enhances the long-term durability and reliability of the helical pile in complex marine environments.

[0035] Further optimization of the scheme: the structural reinforcement component includes multiple reinforcing ribs 5, which are vertically fixed to the inner wall of the pile body 1.

[0036] In this embodiment, the pile body 1 is not a traditional uniformly thick circular tube, but a hollow thin-walled structure with internal reinforcing ribs designed based on the principle of topology optimization. Sensitive areas for material distribution are determined based on the maximum torque condition during pile driving and the maximum bending moment condition during service. Reinforcing ribs 5 are axially arranged inside the pile body 1. In areas where the pile body 1 experiences high torque and high bending moment, the distribution density of the reinforcing ribs 5 is higher, or the cross-sectional size of the reinforcing ribs 5 is larger; in areas with lower stress, the wall thickness of the pile body 1 is thinner, or the distribution of the reinforcing ribs 5 is sparser. This design, while ensuring that the overall torsional stiffness and bending stiffness meet the design requirements, eliminates redundant material, thereby reducing the overall mass of the pile body.

[0037] The design is further optimized so that multiple through holes 11 are opened on the blade surface of the guide leaf segment 9 and the bearing leaf segment 10, and the multiple through holes 11 are evenly distributed.

[0038] To further optimize the design, a cutting edge 14 is provided on the side of the through hole 11 facing the spiral direction of the guide blade segment 9 and the bearing blade segment 10. The cutting edge 14 is used to cut the soil to reduce the spiraling resistance.

[0039] In a further optimized design, multiple reinforcing plates 13 are fixedly connected to the bottom of the blades of the guide vane segment 9 and the carrier vane segment 10. The multiple reinforcing plates 13 are located on the sides of the multiple through holes 11. The reinforcing plates 13 are arc-shaped and are arranged parallel to the rotation direction of the blades of the guide vane segment 9 and the carrier vane segment 10.

[0040] In this embodiment, two sets of reinforcing plates 13 are provided on both sides of the through hole 11 along the radial direction of the pile body 1.

[0041] By creating multiple through holes 11 on the blade surface, three objectives can be achieved: first, to further reduce the blade's weight and aid in lightweighting; second, to allow some soil to pass through during penetration, reducing soil extrusion resistance; and third, to provide a sharp cutting edge 14 on the side of the through hole 11 facing the direction of rotation, forming an auxiliary cutting structure. To ensure local strength after the holes are created, an arc-shaped reinforcing plate 13 is welded to the side of the blade bottom near each through hole 11. By setting this reinforcing plate, the purpose of compensating for the strength reduction caused by the holes and ensuring the overall structural integrity of the blade can be achieved.

[0042] In a further optimized design, a connecting flange 3 is fixedly connected to the top of the pile body 1 to rigidly connect the pile body 1 to the superstructure.

[0043] In this embodiment, an external stiffening rib corresponding to the internal reinforcing rib 5 is provided below the connecting flange 3 for a high-strength rigid connection with the upper platform structure.

[0044] The working process of this embodiment is as follows: During construction, a hydraulic torque actuator clamps the connecting flange 3 at the top of the pile, simultaneously applying rotational torque and downward axial pressure. The guide pile tip 4 and the guide blade segment 9 with serrated grooves 8 first contact the seabed. Under the action of torque and downward pressure, the edges of the serrated grooves 8 efficiently cut the soil, and the small-pitch blades smoothly "guide" the pile into the soil layer with relatively low torque. As penetration deepens, the large-pitch bearing blade segment 10 begins to work, continuously compacting the surrounding soil and forming a tight interlock with it. The anti-overturning blade segment 12 embeds into the mud surface, significantly enhancing the overall anti-overturning stability of the helical pile. The reinforcing ribs 5 inside the pile body ensure structural stability and prevent buckling when transmitting huge torques. After the pile is driven to the design elevation, it is fixed to the superstructure via the connecting flange 3. In subsequent long-term service, the composite anti-corrosion layer formed by the electrochemical anti-corrosion layer 6 and the shielding anti-corrosion layer 7 effectively resists marine corrosion, while the strong embedding of the variable-pitch blades with the surrounding soil provides stable and reliable horizontal, vertical, and tensile bearing capacity for the entire marine facility.

[0045] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0046] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A corrosion resistant lightweight steel screw pile suitable for complex seabed, characterized in that, The utility model relates to a kind of spiral pile, including: Pile body (1), the pile body (1) is thin-walled pipe structure, structural reinforcement assembly is provided on the inner wall of the pile body (1); Spiral blade assembly (2), including the guide blade segment (9) and the load blade segment (10) that guide blade segment (9) and load blade segment (10) are sequentially arranged from lower to upper along the outer wall of the pile body (1), the top of the guide blade segment (9) is connected with the bottom of the load blade segment (10), the pitch of the guide blade segment (9) and the pitch of the load blade segment (10) sequentially increase from lower to upper, and the maximum pitch of the guide blade segment (9) is less than the minimum pitch of the load blade segment (10), the blade outer edge of the guide blade segment (9), load blade segment (10) is provided with cutting member, for destroying the soil structure at blade outer edge; Anti-corrosion assembly, including electrochemical anticorrosion layer (6) and shielding anticorrosion layer (7) that are sequentially coated on the surface of the pile body (1), guide blade segment (9), load blade segment (10).

2. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 1, characterized in that: The lead angle of the guide blade segment (9) is less than the lead angle of the load blade segment (10).

3. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 1, characterized in that: The sidewall of the pile body (1) is fixedly connected with anti-overturning blade segment (12), the anti-overturning blade segment (12) is arranged at the top of the load blade segment (10), the outer diameter of the anti-overturning blade segment (12) is greater than the outer diameter of the load blade segment (10), and the number of turns of the anti-overturning blade segment (12) is 1 turn. The bottom of the pile body (1) is provided with a guide pile tip (4).

4. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 1, characterized in that: The cutting member includes a plurality of sawtooth grooves (8) opened in the blade outer edge of the guide blade segment (9) and the load blade segment (10), and the plurality of sawtooth grooves (8) are equally spaced.

5. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 3, characterized in that: The electrochemical anticorrosion layer (6) is a hot-dip galvanized layer covering the outer surfaces of the pile body (1), guide blade segment (9), load blade segment (10) and anti-overturning blade segment (12), and the shielding anticorrosion layer (7) is a modified epoxy coating covering the surface of the electrochemical anticorrosion layer (6).

6. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 1, characterized in that: The structural reinforcement assembly includes a plurality of reinforcing ribs (5) vertically fixedly connected to the inner wall of the pile body (1).

7. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 1, characterized in that: A plurality of through holes (11) are formed in the blade surface of the guide blade segment (9) and the load blade segment (10), and the plurality of through holes (11) are equally spaced.

8. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 7, characterized in that: The through hole (11) is provided with a cutting edge (14) on the side facing the direction of rotation of the guide blade segment (9) and the load blade segment (10), and the cutting edge (14) is used for cutting the soil to reduce the resistance to rotation.

9. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 7, characterized in that: The bottom of the guide blade segment (9) and the load blade segment (10) is fixedly connected with a plurality of reinforcing plates (13), and the plurality of reinforcing plates (13) are respectively located on the side of the plurality of through holes (11). The reinforcing plate (13) is arc-shaped and arranged in parallel with the rotation direction of the guide blade segment (9) and the load blade segment (10).

10. A corrosion resistant lightweight steel screw pile suitable for complex seabed according to claim 7, characterized in that: The top of the pile body (1) is fixedly connected with a connecting flange (3) for rigidly connecting the pile body (1) with the upper structure.

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