Pile structure for offshore wind turbines and installation method thereof

Abstract

Disclosed herein is a pile structure for an offshore wind turbine and its installation method. The pile structure (100) includes a pile body (101) having a pile tip (101a) configured to be inserted into a ground (5), such as the seabed, and a fluid delivery device (110) configured to deliver fluid to a surface of the pile body (101) adjacent to the pile tip (101a) in a direction away from the pile tip (101a). The fluid delivery device (110) is configured to deliver fluid at a local differential pressure, i.e., low pressure, between 0 and 8 bar.

Description

[Technical Field]

[0001] The present invention relates in particular but not exclusively to pile structures for offshore wind turbines and methods for their installation. [Background technology]

[0002] Offshore wind turbines can be broadly divided into two different categories: floating offshore wind turbines and seabed-fixed offshore wind turbines (Non-Patent Document 1).

[0003] A floating wind turbine comprises a floating platform, such as a spar platform, semi-submersible platform, or tension leg platform, held in place by a number of mooring lines. The wind turbine tower is attached to the platform.

[0004] Seabed-anchored offshore wind turbines maintain direct contact between the wind turbine structure and the seabed. Examples of such structures include gravity foundations, suction bucket anchors, and piles, which use their own weight to resist any lateral forces acting on the wind turbine. Both suction bucket anchors and piles must be inserted into the seabed and use contact forces between their sides and the seabed to resist any lateral forces acting on the wind turbine.

[0005] Suction bucket anchors are large caisson or tank-type structures that are installed into the seabed using pumps. The pumps are arranged to expel water from the caisson structure, causing the resulting pressure differential to force or "suck" the caisson structure into the seabed. Suction bucket anchors may function as mono-bucket foundations or as part of a multi-bucket foundation in combination with a jacket structure.

[0006] In contrast, piles are elongated structures that are driven into soil, including but not limited to, the seabed, using a hammer-driven method. Pile structures can be tubular or cylindrical, or they can be sheet piles or H-piles. Hammer-driven methods involve driving piles into the seabed using a pile driving hammer or impact hammer. Driving piles can generate forces up to 50 to 100 times the force of gravity, and accordingly, pile structures must be able to withstand these forces. Piles are installed vertically to provide maximum lateral frictional support with the seabed. Piles can function as single-pile foundations or can be combined with a jacket structure to form part of a multi-pile foundation.

[0007] Piles are a competitive foundation solution for offshore wind turbine installations due to their simple construction and installation.

[0008] However, pile driving generates noise as the hammer strikes the pile. Pile driving noise is broadband and the noise generated can exceed several hundred decibels (dB) in the surrounding area. This noise generation can be problematic for marine life, which is why various regulations have been put in place to limit the amount of noise generated during pile driving.

[0009] Noise generated during pile driving can potentially be mitigated using various noise reduction solutions (see Table 4 in Non-Patent Document 1), however, such solutions increase the cost of pile installation and experience with their effectiveness is mixed.

[0010] Using less force when driving the piles can also reduce the amount of noise generated, however larger pile structures (which may be used to support offshore wind turbines in larger and / or deeper waters) require more force to properly install.

[0011] Additionally, various marine soils can present challenges when installing piles. For example, soils containing glauconite may require greater driving force to overcome the high shear strength of the glauconite soil when inserting the pile into the soil. Thus, there may be areas where installing piles is currently impossible due to the high resistance the soil presents during insertion. This is because the high resistance may require the use of larger pile driving hammers, which may be less cost-effective and / or generate more noise than is desirable for use near marine life.

[0012] Additionally, processes such as "jetting" may be used during pile driving to aid in the insertion of the actual pile structure into the seabed, as used in suction bucket foundations and other situations. Jetting typically involves removing soil from directly beneath the pile toe by spraying a jet of water directly onto the soil in the direction of pile insertion (see Non-Patent Document 2). Jetting requires high flow rates and pressures. The pressures typically associated with jetting are high and can be on the order of 10 bar (1000 kPa) to 100 bar (10 MPa) relative to the pressure at the jetting location. While jetting may facilitate the insertion of the pile structure by removing soil from beneath the pile toe, soil removal weakens the structure of the seabed strata on which the pile structure is installed. This reduces the strata's resistance to lateral loads, thereby weakening the installed pile structure's ability to withstand lateral loads. For this reason, jetting is generally avoided when installing pile structures for offshore wind turbines.

[0013] Thus, there are practical limitations on the size of pile structures used for offshore wind turbines, particularly when used with certain types of seabed formations, and there are also drawbacks associated with using larger pile structures for offshore wind turbines. It would be desirable to address and / or overcome the above-mentioned limitations. [Prior art documents] [Non-patent literature]

[0014] [Non-Patent Document 1] Jiang, Z. (2021) “Installation of offshore wind turbines:A technical review”, Renewable and Sustainable Energy Reviews, Vol.139 [Non-patent document 2] Cathie et al. (2019) “Suction Installed Caisson Foundations for Offshore Wind:Design Guidelines”, Offshore Wind Accelerator, February, page 56 Summary of the Invention [Means for solving the problem]

[0015] According to a first aspect of the present invention, there is provided a pile structure comprising a pile body having a pile tip configured to be inserted into ground, and a fluid delivery device configured to deliver fluid to a surface of the pile body adjacent to the pile tip in a direction away from the pile tip. In a preferred embodiment, the fluid delivery device is configured to deliver fluid to the surface of the pile body at a local pressure difference of between 0 and 8 bar.

[0016] The present invention thus relates to the delivery of liquid at relatively low pressures compared to those used for jetting, as it serves a somewhat different purpose (as explained below). Indeed, as will be further discussed, in many applications much lower pressures are preferred. Viewed from a second aspect, the present invention therefore provides a pile structure comprising a pile body having a pile tip configured for insertion into the ground, and a fluid delivery device configured to deliver fluid to a surface of the pile body adjacent the pile tip at a local differential pressure of between 0 and 8 bar (0 and 800 kPa). In a preferred embodiment, the fluid delivery device is configured to deliver fluid to the surface of the pile body at a local differential pressure of between 0 and 5 bar (0 and 500 kPa).

[0017] For the avoidance of doubt, the term "local differential pressure" as used herein refers to the pressure of the delivered fluid compared to the ambient pressure at the location of the pile toe. Thus, for example, if the ground is a seabed or depending on the water table in the soil, the absolute pressure will increase with depth.

[0018] By delivering fluid proximate the pile toe of the pile body, the fluid delivery device may function to reduce the effective stresses and / or forces (e.g., frictional forces acting between the ground soil and the pile wall) experienced by the pile body as it is inserted into the ground. This is achieved because the fluid delivery device functions by a number of mechanisms to reduce the effective stresses and / or forces experienced by the pile body during insertion into the ground. However, because the fluid is delivered at relatively low pressure and / or in a direction away from the pile toe (i.e., generally opposite the direction of insertion), it is not a form of jetting.

[0019] As will be described further below, the present invention is particularly useful for piles used to support offshore wind turbines.

[0020] In viscosities and soils that contain a significant proportion of clay and / or exhibit clay-like properties, the delivered fluid may particularly reduce the undrained shear strength at the soil / pile structure interface. Therefore, the driving force required to properly install the pile structure in the ground may be reduced, which may reduce the amount of noise generated during installation and / or allow for the use of smaller pile driving equipment, such as pile drivers or impact hammers, relative to the size of the pile structure. Alternatively, since less energy is required to move the pile structure in the ground, a larger pile structure may be installed in the ground relative to the required pile driving force.

[0021] Furthermore, because less energy is required to move the pile structure in the ground, the present invention may better encourage the use of alternative pile driving tools such as vibratory hammers, which generate lower levels of noise during use, or other pile driving tools.

[0022] The delivered fluid may function to lubricate the surface of the pile body, which may reduce the frictional forces experienced by the pile body during insertion into the ground. Thus, the fluid delivery device may function by a number of mechanisms to reduce the effective stresses and / or forces experienced by the pile body during insertion into the ground.

[0023] Additionally, the delivered fluid may act to reduce effective stresses in various soils of the ground that may resist pile toe penetration.

[0024] For example, soil layers containing clay may exhibit high effective stresses. Delivery of fluid to these clays may result in mixing of the clay and fluid, locally plasticizing the clay beyond its reformed shear strength, and thus providing less resistance to the insertion of the pile body. Furthermore, the plasticized clay with increased moisture content may form a lubricating layer on the surface of the pile body, thereby reducing the frictional forces experienced by the pile body as it is inserted into the ground.

[0025] Similar to clay-containing soil layers, glauconite-containing soil layers (e.g., glauconite sand) can also exhibit high resistance to pile toe penetration. Glauconite, like some clays, can respond to the insertion of an object (such as the toe of a pile body) by generating localized negative pore water pressures. This negative pore pressure arises due to the low permeability of the sediment and increases the shear strength of the sediment. Adding fluid to the sediment during pile insertion can reduce the shear strength of the sediment by shifting the material's negative pore pressure toward or toward a positive value (i.e., exhibiting overpressure). This can reduce the driving force required to insert the pile body into such soil layers. Furthermore, because these regions of high negative pore pressure tend to occur near the pile body (e.g., within a few centimeters of the pile body), delivering fluid to the surface of the pile body is sufficient to reduce the shear strength of these soil layers.

[0026] Pile structures may be particularly useful in the field of offshore wind turbines. Pile structures (e.g., for offshore wind turbines) may provide foundation structures that are less disruptive to marine life during installation by reducing frictional forces experienced during insertion; may increase the available offshore locations suitable for offshore wind turbine installation by allowing wind turbine foundation structures to be more easily installed in locations with soils containing glauconite and / or high-strength clay; and may facilitate the installation of larger offshore wind turbines, which may be capable of generating greater amounts of electricity, by allowing larger pile structures to be used. The pile structure may be an offshore pile structure.

[0027] The ground is ground comprising one or more soil layers. The ground may be on land or offshore. The ground may be the seabed.

[0028] In the case of a pile structure such as that described in the first embodiment, by delivering the fluid in a direction away from the pile tip, the fluid can be more efficiently applied to and lubricated on the surface of the pile body. By delivering the fluid in a direction opposite to the insertion direction of the pile structure, the possibility that the delivery of the fluid from the fluid delivery device will be blocked by soil from the ground is also reduced.

[0029] The direction away from the pile toe can be considered as the direction away from the pile toe and toward the pile head, and / or as the direction extending in the opposite direction to the direction in which the pile structure is inserted into the ground. However, it will be understood that not all of the fluid needs to be delivered precisely in this direction. The present invention simply requires that a sufficient amount of fluid be delivered generally in the aforementioned direction so that the fluid is delivered adjacent the sidewall of the pile above the fluid delivery device. Nevertheless, in preferred forms of the present invention, fluid use is optimized by delivering the fluid through apertures or nozzles oriented substantially in the aforementioned direction and / or with the aid of a filter.

[0030] The fluid delivery device of the second aspect may also be configured to deliver fluid in a direction away from the pile tip, and therefore the pile structure of the second aspect may similarly benefit from the technical advantages discussed above, if such a feature is present.

[0031] For pile structures such as those described in the second embodiment, by delivering fluid to the pile body (i.e., providing lubrication) at the same low differential pressure, disturbance of the soil in the ground caused by fluid flow can be reduced when the pile is inserted into the ground. Thus, once the pile structure is installed, the ground can effectively provide lateral support to the pile structure, thereby improving the stability of the facility. This is in stark contrast to fluid being injected into the soil during jetting, which is often done at pressures of 10 bar to 100 bar (1 MPa to 10 MPa) or more, which can significantly weaken the soil strata.

[0032] As described above, the fluid delivery device provides lubrication while minimizing impact on the strength of the surrounding foundation. Therefore, the fluid is preferably delivered at the lowest pressure sufficient to deliver it. The absolute pressure, therefore, depends on conditions at the location where the fluid is delivered, such as local formation pressure or pressure at or below the ground, such as the seabed (e.g., in the area where the fluid is delivered, toward the pile toe). Therefore, the fluid delivery device is configured to deliver the fluid at a pressure between 0 and 8 bar (0 and 800 kPa); preferably, between 0 and 5 bar (0 and 500 kPa), or more preferably, between 0 and 3 bar (0 and 300 kPa), where this pressure is the differential pressure relative to the local ambient pressure. The fluid delivery device may be configured to deliver the fluid at a pressure of at least 0.1 bar (10 kPa), at least 0.2 bar (20 kPa), at least 0.5 bar (50 kPa), or at least 1 bar (100 kPa). The local pressure differential may define the lower limit of any of the ranges mentioned above.

[0033] The fluid delivery device may be configured to be driven by a hydrostatic head, thereby supplying fluid under gravity. Thus, the fluid body may be provided with sufficient head and placed in fluid communication with the fluid delivery device. This may be considered a first / passive mode of operation. Since the purpose of fluid delivery is primarily to lubricate the pile body, the use of a hydrostatic head may be sufficient. The fluid body is located inside the pile body, preferably within the body itself (i.e., no tank or the like is required). The fluid body may have a height (i.e., head) higher than the surrounding sea level. The fluid body is preferably a body of seawater.

[0034] However, if desired, for example in applications where high pressure is required to ensure fluid delivery, the fluid delivery device may be configured to be driven by a pump in fluid communication with the fluid delivery device. This may be considered a second / active mode of operation. The pump may be a submersible pump or a pump provided on a nearby vessel.

[0035] The fluid delivery device may be configured to switch between a first mode of operation and a second mode of operation.

[0036] The pile structure may be suitable for offshore structures and / or offshore installations. For example, the pile structure may be suitable for an offshore platform and may be configured to be inserted into or installed on the seabed. Although the invention is applicable in many situations, the pile structure may be particularly suitable for supporting offshore wind turbines. In this regard, the pile structure may form a single pile supporting the wind turbine, or may form part of a pile pin structure in a multi-pile jacket structure.

[0037] In this specification, the distal end of the pile body is referred to as the pile tip. The section of the pile body located between the pile tip and the pile head (i.e., the proximal end of the pile body) is referred to as the middle section. The pile tip and / or pile head may be generally flat, not sharpened, and may lie perpendicular to the surface of the pile body.

[0038] In some arrangements, the pile body may be a sheet pile, an H-pile, or a solid cylindrical pile body.

[0039] In another arrangement, the pile body may be a tubular pile body, i.e. a pile body of tubular structure or form. The pile body may have inner and outer surfaces defined relative to the surface of the tubular structure.

[0040] The pile body may be circular, elliptical, annular, or polygonal in cross section.

[0041] The pile body may be a generally cylindrical tubular structure and may be made of steel, for example steel grade S355. The pile toe is open, i.e., circular in cross section. The pile cap may also be open or closed, i.e., forming a disk.

[0042] The overall diameter of the pile body may be at least 2 m wide, 5 m wide, 8 m wide, 10 m wide, or more. If the pile structure is a pin pile structure, for example, used to attach the legs of a jacket structure, the overall diameter may be less than 5 m, or less than 3 m. If the pile structure is a single pile structure, the overall diameter may be at least 5 m, at least 8 m, or at least 10 m. The diameter of the pile structure may be based on many factors, including: the depth of the ocean where the pile structure will be installed; or the size of the equipment that will be attached to the pile structure.

[0043] The pile body is preferably tapered at the top, which may facilitate driving of the pile structure, for example with a pile driving hammer. The central section of the pile body preferably has a constant outer diameter.

[0044] In some embodiments, the pile body may be formed from multiple sections, or "cans", welded together, each section being at least 2m, 3m, 4m, or 5m in height.

[0045] The thickness of the wall of the pile body may vary along its length. Varying the thickness of the pile body in this manner may minimize stress and / or fatigue experienced by the pile body during driving. The wall may gradually thicken along the length of the pile body, extending from the pile head to the pile tip. In some arrangements, the pile body may be thickest toward the central section of the pile body and then taper again toward the pile tip. The pile body may be thickest, or thicken again, at the bottom section of the pile body (i.e., the pile tip). This may resist buckling and / or ovalization of the pile body during driving.

[0046] The thickest section of the pile body may also be the lowest section of the pile body, and its wall thickness may be between 100 and 120 mm. The thinnest section of the pile body may also be the highest section of the pile body, and its wall thickness may be between 50 and 70 mm.

[0047] The pile body may have a length of between 20m and 100m, between 30m and 90m, between 40m and 80m, or between 50m and 70m. The pile body may be configured to be embedded into the seabed to a depth of at least 10m, at least 20m, at least 30m, or at least 40m. The pile body may be configured to protrude from the seabed at least 3m, at least 45m, 10m, 20m, at least 30m, at least 40m, at least 50m, or at least 60m.

[0048] The pile body may include a releasable hatch, which is fluid-tight when closed, and which may provide access to the interior of the pile structure, the hatch being positioned so as to be above the seabed when the pile structure is installed on the seabed.

[0049] The fluid may be water. More particularly, seawater may be used as the fluid, such as when the pile structure is installed on the seabed. When water / seawater is used as the fluid, the fluid delivery device may be considered a water delivery device. However, other fluids are also envisioned. For example, the fluid may be or include bentonite mud. Bentonite mud may be particularly useful in sandy soils.

[0050] Preferably, the fluid delivery device is located substantially at the pile tip, i.e., immediately behind the pile tip, which is likely to experience the greatest resistance during driving of the pile body, so locating the fluid delivery device at the pile tip may have the greatest effect in reducing frictional forces / effective stresses experienced during insertion.

[0051] The fluid delivery device may be configured to deliver fluid to an exterior and / or interior surface of the pile body.

[0052] The fluid delivery device may comprise a manifold having one or more (ie, one or multiple) apertures configured to deliver the fluid.

[0053] The manifold may extend around the pile body. The manifold may surround the pile body or extend circumferentially around the pile body.

[0054] The manifold may have an upper surface and a side surface. As will be further described below, a driving shoe (i.e., a reinforcing element for the lower end of the pile) may be provided. The pile body and the driving shoe may each define further side surfaces and a lower surface. Alternatively, the manifold may have further side surfaces and a lower surface that are integrally formed.

[0055] The manifold may define a plenum that extends around the pile body. If the pile body is cylindrical, elliptical, or circular in cross section, the manifold may be an annular member (such as an annular ring member) that defines a plenum that extends circumferentially relative to the pile body. If the pile body is a sheet pile or H-pile, the manifold may extend along or around the periphery of the pile body.

[0056] The plenum is positioned to receive the fluid flow, and thus is configured to convey the fluid flow delivered to the surface of the pile body.

[0057] In other words, the manifold can define a cavity positioned to receive a fluid flow, and the manifold also has one or more apertures each configured to deliver the fluid flow from the cavity and to the surface of the pile body.

[0058] The one or more apertures may be multiple apertures.

[0059] The multiple apertures may be comprised of multiple nozzles, holes, or outlets. The apertures are generally configured to direct the flow of fluid delivered from the fluid delivery device. The multiple apertures may be formed on the upper surface of the manifold, i.e., the surface facing away from the pile tip. The apertures may therefore be arranged to deliver the flow of fluid in a direction away from the pile tip. Even more advantageously, the multiple apertures may therefore be formed on a surface that does not face the insertion direction of the pile body. This may make the apertures less likely to be blocked or clogged by soil during insertion of the pile body.

[0060] Each aperture may have a diameter of at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm. Preferably, each aperture has a diameter between 1 mm and 3 mm.

[0061] The multiple apertures are preferably distributed circumferentially, more preferably uniformly, around the manifold. The apertures may be spaced about 5 mm apart, or between 3 and 10 mm apart. The apertures may be spaced less than 10 mm apart, less than 20 mm apart, less than 30 mm apart, less than 40 mm apart, or less than 50 mm apart.

[0062] Alternatively, the apertures may be spaced between 20 and 50 mm apart. The apertures may be spaced at least 20 mm apart, at least 30 mm apart, at least 40 mm apart, or at least 50 mm apart.

[0063] The apertures may be formed during manufacture of the manifold, for example during casting, or may be formed by drilling and / or cutting after manufacture of the manifold.

[0064] The one or more apertures may consist of a single continuous aperture.

[0065] The single continuous aperture surrounds or encircles, i.e., is continuous with, part or all of the pile body. The single continuous aperture may be an annular slit or channel formed in the upper surface of the manifold.

[0066] By providing a single continuous aperture circumferentially surrounding the wall of the pile structure, fluid can be more evenly and completely delivered to the surface of the pile body adjacent the pile tip because the single continuous aperture is not interrupted by other elements such as the surface of the manifold, etc. This arrangement may promote lubrication of the surface of the pile body.

[0067] Alternatively, the one or more apertures may be comprised of multiple apertures, each an elongated slit or opening extending around the circumference of the pile body. Each aperture may substantially surround at least one-tenth, at least one-sixth, at least one-fifth, at least one-quarter, at least one-third, or at least one-half of the circumference of the pile body. Each of the one or more apertures may provide an arrangement that reduces the number of interruptions or gaps separating the apertures. Such an arrangement may allow for more uniform and complete delivery of fluid to the surface of the pile body adjacent the pile tip.

[0068] The fluid delivery device may further include one or more filters that occupy one or more apertures. The filters are configured to be permeable to the fluid and selected to be impermeable to soil without impairing fluid flow. That is, the filters are configured to prevent soil from entering the manifold, while still allowing fluid flow therethrough. The filters preferably match the size and shape of the one or more apertures so that the apertures are fully occupied by the filters. For ease of reference only, the filters may each be referred to as a first filter.

[0069] Each first filter occupies a respective aperture. The one or more first filters may be particularly useful when the one or more apertures consist of a single continuous aperture, or when each aperture is an elongated slit. When the one or more apertures consist of a single continuous aperture, preferably the one or more first filters consist of a single continuous filter occupying the single continuous aperture.

[0070] A first filter is placed in one or more apertures to allow water to be delivered from the fluid delivery device but prevent soil from entering the fluid delivery device.

[0071] The first filter may be configured to be impermeable to soil without impeding fluid flow as described above, and therefore impermeable to particulate matter above a predetermined particle size.

[0072] The first filter may be one of a sand-epoxy filter, a Vyon filter, or a geotextile filter. The filter may include one or more layers, each layer including a woven or nonwoven material. The filter may include a volume element or layer and a cover layer. The volume element may primarily promote fluid flow, and the cover layer may primarily impede soil or sediment flow. The permeability of the first filter may be selected depending on a predetermined delivery pressure of the fluid from the fluid delivery device and a predetermined flow rate of the fluid.

[0073] The fluid delivery device may further include a filter configured to extend from the manifold in a direction opposite to the insertion direction of the pile tip. The filter is configured to be as impermeable to the soil as possible without impeding the flow of fluid, and to be permeable to the fluid. Thus, the filter may be configured to be impermeable to particulate matter above a predetermined particle size. This filter may be referred to as the second filter simply for ease of reference.

[0074] The second filter may promote fluid flow along a surface of the pile body, for example, the second filter may be positioned to direct fluid along a surface of the pile body adjacent the pile tip, in use.

[0075] Additionally, the second filter can facilitate fluid delivery to the soil near the surface of the pile body adjacent to the pile tip. For example, during the insertion of the pile structure, a cavity or soil overhang may form behind the manifold. The second filter can improve contact between the pile structure and the adjacent soil so that fluid is effectively delivered to the interface between the soil and the pile structure. This can be particularly beneficial when the pile tip is located in soil with negative pore water pressure.

[0076] The second filter may be secured to the manifold using glue, a welded joint, or a combination of the two.

[0077] The second filter may be a geotextile filter defining a skirt extending from the manifold, with one or more apertures located between the skirt and the pile body. The geotextile filter may be a reinforced geotextile membrane. The skirt may also be considered a collar. The geotextile filter may comprise one or more layers, each layer comprising a woven or nonwoven material. The filter may comprise a volume element or layer and a cover layer. The volume element may primarily promote fluid flow, while the cover layer may primarily impede soil or sediment flow.

[0078] The geotextile filter can be considered to have a first end and a second end. The first end is secured to the manifold, e.g., toward the edge of the manifold distal from the pile body. The second end is a free end extending downstream of one or more apertures. In some configurations, the free end is not secured to the surface of the pile body at all, i.e., the free end is free throughout. In other configurations, the second end is secured intermittently or periodically to the surface of the pile body proximate the pile tip. The free end may be secured at intervals of 5 to 30 cm, and / or at least every 5 cm, at least every 10 cm, at least every 15 cm, at least every 20 cm, or at least every 25 cm, such that the free end is intermittently free or unsecured.

[0079] The geotextile filter may be reinforced and / or it may be a deformable fabric. The geotextile filter may be configured to sag in a direction opposite to the direction of the pile body during insertion of the pile body.

[0080] The skirt's shape can promote fluid flow along the surface of the pile body while also providing an interface for fluid delivery to the soil in contact with the skirt. This can be particularly beneficial when the pile toe is located in soil with negative pore water pressure. The geotextile filter can also serve to prevent soil from occupying the space immediately downstream of one or more apertures to maintain proper function of the fluid delivery device.

[0081] Alternatively, the second filter may define a sloped surface extending between the manifold and the pile body, with one or more apertures covered by a geotextile fabric filter. The second filter may be a geotextile filter, a Vyon filter, or a sand-epoxy filter. The filter may comprise one or more layers, each comprising a woven or nonwoven fabric material. The filter may comprise a volume element or layer and a cover layer. The volume element may primarily promote fluid flow, and the cover layer may primarily impede soil or sediment flow.

[0082] The sloped surface may cover one or more apertures, thereby preventing soil penetration into the aperture or apertures. The sloped surface provides a surface that contacts the surrounding soil, effectively delivering fluid to the soil as well as the surface of the pile body. This can be particularly beneficial when the pile toe is located in soil with negative pore water pressure.

[0083] The sloped surface may define a volume downstream of the one or more apertures between the second filter, the manifold, and the pile body. For example, fluid may be encouraged to flow along the surface of the pile body during insertion by one or more of the wicking action of the second filter or the movement of the pile body during insertion. In such an arrangement, the second filter may preferably be a geotextile filter, such as an elongated geotextile membrane or fabric.

[0084] Alternatively, the second filter may have a tapered cross section and may be flush with both the pile body and the upper surface of the manifold, i.e., the second filter may extend between the pile body and the manifold and along the surfaces of the pile body and the manifold, respectively.

[0085] The manifold may be configured to receive fluid flow via channels formed through the pile body, i.e., the manifold may be configured to receive fluid flow from a conduit located on an opposite side of the pile body from the manifold, and the pile body may include a number of said channels formed therethrough.

[0086] Additionally or alternatively, the manifold may be configured to receive fluid flow through openings formed in a surface of the manifold facing away from the pile tip. That is, the manifold may be configured to receive fluid flow from a conduit located on the same side of the pile body as the manifold. The manifold may comprise a number of such openings distributed circumferentially around the manifold. The openings may be distributed intermittently or coincident with one or more apertures.

[0087] The manifold may extend circumferentially around an outer surface of the pile body, with the one or more apertures configured to deliver fluid to the outer surface of the pile body, i.e., the manifold may be considered an external manifold relative to the pile body.

[0088] Alternatively, the manifold may extend circumferentially around the inner surface of the pile body, with the one or more apertures configured to deliver fluid to the inner surface of the pile body, i.e., the manifold may be considered an internal manifold relative to the pile body.

[0089] The use of internal manifolds can be particularly beneficial in pin pile structures, such as foundation structures with jacket structures (e.g., as described in the third aspect below) or pile structures used as part of other multi-pile foundations, and / or narrower pile structures.

[0090] The manifold may include a transition portion extending along the pile body in a direction away from the pile toe. The transition portion defines a slope for directing water toward the surface of the pile body proximate the pile toe. The slope may extend between the manifold and the pile body and may be configured to guide or direct fluid toward the surface of the pile body. The slope may be convex, concave, or linear, or may be a combination of the above slopes. The transition portion may define one of a chamfer, a fillet, or a bevel.

[0091] The transition portion defines a transition between the manifold and the surface of the pile body. The use of the transition portion may facilitate fluid flow along the surface of the pile body. For example, providing a fillet (typically a concave fillet due to an internal corner formed between the manifold and the surface of the pile body) may result in a smoother and more regulated flow of fluid from one or more apertures along the surface of the pile body.

[0092] The manifold may be a first manifold comprising a first set of one or more apertures, and the fluid delivery device comprises a second manifold having a second set of one or more apertures configured to deliver the fluid, the second manifold extending circumferentially within the inner surface of the pile body, the second set of one or more apertures configured to deliver the fluid to the inner surface of the pile body.

[0093] In other words, the fluid delivery device may include both an internal manifold and an external manifold.

[0094] By delivering fluid to both the inner and outer surfaces of the pile body, a greater reduction in frictional forces experienced can be achieved because the pile body is lubricated at two surfaces that come into contact with the ground soil, rather than just one.

[0095] The internal manifold and the external manifold may each be configured to receive fluid flow from a respective conduit. Additionally or alternatively, the internal manifold and the external manifold may be in fluid communication via a channel formed through the pile body.

[0096] The driving shoe may be located at the tip of the pile. The driving shoe is sometimes called a cutting shoe.

[0097] The driving shoe may have an external and / or internal portion, referred to as an external driving shoe and an internal driving shoe, respectively. The terms "external" and "internal" refer to the location / portion of the driving shoe relative to the wall of the pile body.

[0098] The driving shoe typically projects outward from the surface of the pile body and may facilitate insertion of the pile body into the ground by reducing the frictional forces experienced by the pile body (above the shoe) during insertion.

[0099] The driving shoe may be formed, for example by welding, onto the surface of the pile body at the pile tip. Alternatively, the driving shoe may be integrally formed with the pile body. The driving shoe may be formed, for example, as a thicker section of the pile body to achieve a desired driving shoe profile.

[0100] The dimensions of the driving shoe may be predetermined based on the ground soil conditions at the installation location and / or the desired reduction in resistance experienced during driving.

[0101] The driving shoe may extend, i.e. protrude, from the surface of the pile body by at least 40 mm. The driving shoe may extend from the surface of the pile body by at least 40 mm, at least 50 mm, at least 60 mm, or at least 70 mm.

[0102] The driving shoe may have a length (ie axial height / extension) of between 50 and 200 mm, between 75 and 175 mm, or between 100 and 150 mm.

[0103] The fluid delivery device may be positioned rearward of and in contact with the impact shoe. In other words, the fluid delivery device / fluid delivery device manifold may be located adjacent and proximate to the impact shoe, directly behind the impact shoe.

[0104] By locating the fluid delivery device directly behind the driving shoe, the driving shoe may provide support and / or protection for the fluid delivery device while reducing the likelihood of the fluid delivery device shearing during insertion of the pile body into the ground. Additionally, locating the manifold directly behind the external driving shoe ensures that the fluid delivery device is located near the pile toe for most efficient delivery of fluid to the surface of the pile body.

[0105] The external manifold of the fluid delivery device may be located rearward of and in contact with the external impact shoe.

[0106] The internal manifold of the fluid delivery device may be located rearward of and in contact with the internal impact shoe.

[0107] The manifold may be integrally formed with the driving shoe of the pile body, or alternatively, the manifold may be attached to the driving shoe by, for example, welding or bolts.

[0108] The pile structure may include multiple driving shoes, which may be distributed along the length of the pile body. The use of multiple driving shoes may improve the reduction of friction forces experienced by the pile structure when installed through multiple soil layers.

[0109] The pile structure may include multiple fluid delivery devices. The multiple fluid delivery devices may be distributed along the length of the pile body. The use of multiple fluid delivery devices may improve the delivery of fluid to lubricate the pile body along its length, particularly when the pile structure extends through multiple soil layers during insertion. Each fluid delivery device may be located behind and in contact with a respective driving shoe.

[0110] A conduit may extend along a surface of the pile body, the conduit being configured to provide a flow of fluid to the fluid delivery device.

[0111] The conduit is positioned to extend above the ground. The opening of the conduit may remain above the ground. The length of the conduit may be selected such that the opening of the conduit remains above the ground during and after installation of the pile structure in the ground. This allows the opening of the conduit to remain unobstructed and / or clear of soil or other debris / sediments disturbed during driving of the pile structure. Preferably, the opening of the conduit remains at least 2 m above the ground after installation.

[0112] The conduit may be or consist of a pipe.

[0113] The conduit may be attached to the pile body, for example, by welding (directly or indirectly, for example, via brackets and / or doubler plates), glue, or via one or more brackets arranged to secure the conduit to the pile body. In other words, the conduit does not have to be integrally formed with the pile body.

[0114] During insertion, the pile body is subjected to large forces, for example, by the use of an impact hammer, etc. The pile body should therefore be designed to withstand these forces and not suffer structural failure as a result.

[0115] Forming the conduit integrally with the pile body can weaken the structure, so while it is possible to design a pile structure with the conduit formed integrally with the pile body, it is not preferred.

[0116] Alternatively, by providing the conduit attached to the pile body, the conduit can be at least partially isolated from the pile body so as to be shielded from impact forces experienced during driving of the pile body.

[0117] The conduit may be or consist of a half-pipe or other structure attached to the pile body that defines a channel between it and the pile body.

[0118] The conduit may be configured to provide fluid flow to the fluid delivery device through a channel formed in the pile body. Alternatively, the conduit may be configured to provide fluid flow to the fluid delivery device through an opening formed in the top surface of the manifold.

[0119] The conduit may extend along an inner surface of the pile body. This conduit may be considered an internal conduit with respect to the pile body. The conduit may be configured to be in fluid communication with the internal manifold through an opening formed in the top surface of the internal manifold. The conduit may be configured to be in fluid communication with the external manifold through a channel formed through the pile body. When an internal manifold and an external manifold are present, the conduit may be configured to deliver a fluid flow through the internal manifold (e.g., via a channel) to the external manifold.

[0120] Alternatively, the conduit may extend along the outer surface of the pile body. This conduit can be considered an external conduit relative to the pile body. The conduit may be configured to be in fluid communication with the external manifold through an opening formed in the top surface of the external manifold. The conduit may be configured to be in fluid communication with the internal manifold through a channel formed through the pile body. When an internal manifold and an external manifold are present, the conduit may be configured to deliver a fluid flow to the internal manifold through the external manifold (e.g., via a channel).

[0121] The conduit may be configured for use in a passive mode of operation, in which the conduit is in fluid communication with a fluid body located within the pile body and hydrostatic pressure generated by the fluid body drives a flow of fluid to the fluid delivery device. The passive mode may be as described above.

[0122] The conduit may be an internal conduit as described above. The pile body may be configured to contain a fluid body. The fluid body may be bounded by the pile body and the ground. If the pile body is configured to be installed within the seabed, the fluid body may have a height / level / depth above that of the surrounding sea. Thus, the hydrostatic pressure of the fluid body may be higher than the hydrostatic pressure of the adjacent sea at the seabed. The fluid body is preferably a body of seawater.

[0123] Passive operation modes can be particularly effective in delivering fluids to soils that generate negative pore water pressures in response to the insertion of a foreign object. Examples of such soils include those containing glauconite. When the local pore water pressure is negative, the soil acts like a sponge and readily accepts the delivered water. (Some glauconite samples have been found to exhibit negative pore water pressures of up to 200–400 bar, and accordingly, an effective pressure differential can consistently drive fluid through such soils via the fluid delivery device.) In doing so, the soil's pore water pressure approaches positive, reducing its shear strength. Therefore, less energy is required to drive the pile tip into the soil, making insertion easier.

[0124] The passive mode of operation is also particularly advantageous in that once the water level in the fluid body has been artificially raised, no further energy is required to force the fluid through the fluid delivery device. Therefore, this mode of operation of the fluid delivery device is considered a passive mode of operation, or a passive mode of operation. The fluid delivery by the fluid delivery device requires only low pressure to lubricate the surface of the pile body, so high-pressure pumping equipment is not required for some soils. Therefore, the potential energy of the fluid body is sufficient to move the fluid through the fluid delivery device.

[0125] The conduit may be configured to be used in an active mode of operation in which the conduit is in fluid communication with a pump arranged to drive a flow of fluid to a delivery device. The active mode may be an active mode as described above.

[0126] In soils with high effective stress, such as those containing high-strength clays, a larger differential pressure may be required to deliver fluid to the soil (e.g., to generate excess pore water pressure). As previously mentioned, delivering fluid to the clay in this manner can result in mixing of the clay with the fluid, which can plasticize the clay and reduce its resistance to pile insertion. Therefore, the use of a pump can assist in moving the fluid through the fluid delivery device so that it is properly delivered to soils with high effective stress. Therefore, this mode of operation can be referred to as an active mode of operation.

[0127] The pump may be placed in fluid communication with the conduit by direct attachment to the conduit or through an intermediate conduit such as a hose or the like.

[0128] The pump may be a submersible pump and may be configured to provide a flow of seawater or other fluid to the fluid delivery device. Alternatively, the pump may be located on board the vessel and arranged to pump fluid from the vessel.

[0129] The pump may be configured to vary the pressure of the fluid delivered by the fluid delivery device.

[0130] The conduit may be an internal conduit. In such a configuration, the internal conduit may be accessible through a hatch (which may be as described above). The pump may be in fluid communication with the conduit through an intermediate conduit that passes through the hatch.

[0131] The conduit may be located behind the driving shoe, i.e., the conduit may be located completely behind the footprint / cross-sectional area of ​​the driving shoe. The driving shoe may therefore provide protection for the conduit, for example, so that the conduit is not damaged or sheared when the pile structure is inserted into the ground.

[0132] The conduit may protrude from the pile body further than the average protrusion / length of the driving shoe from the pile body. That is, the driving shoe may have a first portion extending a first distance from the pile body. The conduit may extend a third distance from the pile body. The first distance may be smaller than the third distance. The driving shoe may further include a second portion extending a second distance from the pile body, the second distance being greater than the third distance. The second portion of the driving shoe may be located in a straight line with the conduit. In other words, the driving shoe may include a locally extended portion configured to provide protection for the conduit during insertion of the pile structure into the ground. Thus, the driving shoe may be suitably configured to provide protection for the conduit.

[0133] If the conduit is an internal conduit (i.e. located internally relative to the pile body), the conduit may be located aft of the internal driving shoe.

[0134] If the conduit is an external conduit (i.e. located externally relative to the pile body), the conduit may be located behind the external driving shoe.

[0135] The pile structure may comprise a number of said conduits.

[0136] The pile structure may comprise at least two, at least three, at least four, or at least five conduits.

[0137] The multiple conduits may consist of multiple internal and / or external conduits, each of which may be circumferentially distributed around the pile body. Providing multiple conduits may facilitate achieving a desired amount of fluid flow to the fluid delivery device and may also provide redundancy in the event that a conduit breaks and / or fails during use.

[0138] Viewed from a third aspect of the present invention, there is provided an offshore single pile structure, which may be similar to the pile structure of the first or second aspect, i.e. the offshore pile structure of the first and / or second aspect may be a single pile.

[0139] The offshore single pile structure of the third aspect may have one, more than one, or all of the features (including optional features) of the pile structure of the first and / or second aspects, and therefore the above description may be equally applicable to the offshore single pile structure of the third aspect.

[0140] Viewed from a fourth aspect of the present invention, there is provided a foundation structure comprising a jacket structure having a number of legs and a number of pile structures as described in the first and / or second aspects, each leg of the jacket attached to a respective pile structure.

[0141] The offshore single pile structure of the fourth aspect may have one or more or all of the features (including optional features) of the pile structures of the first, second and / or third aspects, and therefore the above description may be equally applicable to the foundation structure of the fourth aspect.

[0142] Viewed from a fifth aspect of the present invention, there is provided an offshore wind turbine structure comprising a wind turbine mounted on a pile structure as described in the first, second or third aspects, or on a foundation structure as described in the fourth aspect.

[0143] The offshore wind turbine of the fifth aspect may have one or more or all of the features (including optional features) of the pile structure of the first, second and / or third aspects and / or the foundation structure of the fourth aspect, and therefore the above description may be equally applicable to the offshore wind turbine of the fifth aspect.

[0144] Viewed from a sixth aspect of the present invention, there is provided a system for installing a pile structure in ground, the system comprising a pile structure as set out in any of the first, second or third aspects and a pile driving hammer.

[0145] The system of the sixth aspect may have one or more or all of the features (including optional features) of the pile structures of the first, second and / or third aspects, and therefore the above description may be equally applicable to the system of the sixth aspect.

[0146] According to a seventh aspect of the present invention, there is provided a method for installing a pile structure in ground, the method comprising: driving a pile tip of a pile body into ground using a pile driving tool; and delivering a fluid to a surface of the pile body adjacent the pile tip. The method also includes at least one of delivering the fluid in a direction away from the pile tip and delivering the fluid at a local pressure difference between 0 and 8 bar.

[0147] The ground may comprise glauconite sand, glauconite, or high strength clay. These materials may behave as described above. The ground may be the seabed. The local pressure difference may be the pressure difference at the seabed relative to the hydrostatic pressure of the sea.

[0148] The pile driving tool may be a pile driving hammer, an impact hammer, a vibratory hammer, or the like.

[0149] The method may include delivering a fluid to an interior and / or exterior surface of the pile body.

[0150] The method may include using a hydrostatic head to force the fluid flow, ie, using the force of gravity to force the fluid flow to be delivered.

[0151] The method may include using a pump to force the flow of fluid.

[0152] The method may include switching between using a hydrostatic head to force the fluid flow and using a pump to force the fluid flow.

[0153] The method may include intermittently or selectively delivering the fluid depending on formation conditions. The fluid may be delivered simultaneously with and / or in conjunction with driving the pile toe.

[0154] Alternatively, the method may include delivering the fluid constantly, i.e. during / simultaneously with the step of driving the pile tip.

[0155] The pile structure may be as described in any of the first, second or third aspects of the invention, and the method may comprise using a system as described in the sixth aspect of the invention. Accordingly, the above statements may be equally applicable to the method of the seventh aspect, which may have one or more or all of the features (including optional features) of the preceding aspects.

[0156] Viewed from an eighth aspect of the present invention, there is provided a method of installing an offshore wind turbine structure in a seabed, the method comprising installing a pile structure in the seabed as described in the seventh aspect, wherein the ground is the seabed, and thereafter attaching the wind turbine to the pile structure.

[0157] The above description may be equally applicable to the method of the eighth aspect, which may have one or more or all of the features (including optional features) of the preceding aspects.

[0158] The wind turbine may be mounted directly on the pile structure.

[0159] Alternatively, the wind turbine may be indirectly attached to the pile structure, for example via a foundation structure, transition piece, or the like.

[0160] A wind turbine may be understood to include at least a hub, a nacelle, and a number of turbine blades. The number of turbine blades is attached to the hub, which is located in front of the nacelle. A wind turbine may also include a tower. The tower may extend between a pile structure / foundation and the nacelle.

[0161] Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0162] [Figure 1] A cross-sectional view of the pile structure installed on the seabed is shown. [Figure 2] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 3] 1 shows a pile structure in plan view from the pile head of the pile structure. [Figure 4] 1 shows a pile structure in plan view from the pile head of the pile structure. [Figure 5] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 6] The cross-sectional representation of the tip of the pile structure is shown. [Figure 7] 1 shows a pile structure in plan view from the pile head of the pile structure. [Figure 8] 1 shows a pile structure in plan view from the pile head of the pile structure. [Figure 9] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 10] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 11] 1 shows a pile structure in plan view from the pile head of the pile structure. [Figure 12] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 13] 1 shows a pile structure in plan view from the pile head of the pile structure. [Figure 14] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 15] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 16] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 17] The cross-sectional representation of the pile tip of the pile structure is shown. [Figure 18] 1 shows a cross section of a pile structure installed in the seabed. [Figure 19] Shows a foundation structure installed within the seabed. DETAILED DESCRIPTION OF THE INVENTION

[0163] FIG. 1 shows a cross-sectional view of a pile structure 100 for a wind turbine installed in the seabed 5. The seabed 5 includes various soil layers 3 and 4. In this embodiment, the pile structure 100 is a single pile structure. The pile structure 100 includes a pile body 101 that, when installed in the seabed 5, extends from below the seabed 5 to above the sea surface 1. The distal end of the pile body 101 (facing the seabed 5) is referred to as the pile tip 101a and is configured to be driven into the seabed 5 as shown. The pile tip 101a is sometimes referred to as the pile toe. The proximal end of the pile body 101 (facing the sea surface 1) is referred to as the pile head 101b and is positioned to receive a transition piece (not shown). The transition piece facilitates attachment of the wind turbine tower to the pile body 101.

[0164] The pile body 101 is a hollow tubular structure and may be referred to as a pipe pile body, pile sleeve, or pile body 101. In this embodiment, the pile body 101 is a cylindrical structure formed from S355 steel and has an overall diameter of 10 m wide. In various embodiments, diameters up to 15 m or greater are contemplated. Diameters less than 5 m are also contemplated. The diameter of the pile structure 100 can be selected based on many factors, including the depth of the sea 2 in which the pile structure 100 will be installed or the size of the equipment (in this case, a wind turbine) to be attached to the pile structure 100. The diameter of the pile body 101 is tapered at the top to facilitate a hammer interface, with the central portion of the pile body 101 having a constant outer diameter.

[0165] The pile body 101 is formed from multiple sections welded together. Each section is 2 to 5 meters high. The wall thickness of the pile body 101 gradually increases as the pile body 101 extends toward the seabed 5 (i.e., as the pile body 101 extends from the pile head 101b to the pile tip 101a) and then decreases again as the pile body extends toward the pile tip. The lowest section, located at the pile tip, is the thickest to resist ovalization / buckling during driving. The wall thickness of the lowest section is 100 to 120 mm. The highest section, which is also the thinnest in this embodiment, has a wall thickness of 50 to 70 mm. Increasing the wall thickness of the pile body 101 in this manner minimizes stress and / or fatigue experienced by the pile body 101 during insertion and subsequent service life.

[0166] In this embodiment, the length of the part of the pile body 101 that is installed in the seabed 5 is 35 m. The length of the part of the pile body 101 that extends above the seabed 5 and above the sea surface 1 is 40 m.

[0167] To insert the pile body 101 into the seabed 5, a pile driving hammer (also known as an impact hammer) is used to drive the pile body 101 into the seabed 5. The pile body 101 is positioned to be struck at its proximal end by the pile driving hammer. The impact of the hammer on the proximal end causes the pile tip 101 a of the pile body 101 to penetrate into the seabed 5.

[0168] The pile tip 101a is shown in more detail in Figure 2, which is a close-up representation of Detail A in Figure 1. The pile body 101 comprises a driving shoe 102, which in this embodiment comprises an outer driving shoe 102a and an inner driving shoe 102b. In various embodiments, only one of the outer driving shoe 102a and the inner driving shoe 102b may be present. It will be understood that the terms "external" and "internal" define the location / portion of the driving shoe 102 relative to the wall of the pile body 101. The driving shoe 102 is sometimes referred to as a cutting shoe.

[0169] The driving shoe 102 is added after fabrication of the pile body 101 by welding. In other embodiments, the driving shoe may be formed integrally with the pile body 101. The driving shoe 102 is 100 mm long and extends or protrudes from the wall of the pile body 101 by 50 mm.

[0170] The provision of the driving shoe 102 may facilitate insertion of the pile body 101 into the seabed 5 by reducing the frictional forces experienced by the pile body 101 during insertion. In this respect, the driving shoe 102 may be effective in cutting into the soil 3, 4 despite increasing the footprint of the pile body 101 at the pile tip 101a.

[0171] The pile driving force required to insert the pile structure 100 into the seabed 5 depends on the size of the pile structure 100. Furthermore, if it is desired to insert the pile structure 100 into seabed soils 3, 4 with high effective stresses, a greater pile driving force will be required to overcome the associated resistance forces experienced during insertion of the pile body 101.

[0172] However, generating a greater pile driving force requires a larger pile driving hammer, which is more expensive. Additionally, the use of a greater pile driving force generates a higher level of noise.

[0173] Therefore, the pile structure 100 in this embodiment and in other embodiments according to the present invention includes a fluid delivery device 110. The fluid delivery device 110 is positioned toward the pile tip 101a of the pile body 101, and preferably substantially at the position of the pile tip 101a, and is configured to deliver fluid to the surface of the pile body 101 adjacent to the pile tip 101a in a direction away from the pile tip 101a (i.e., in a direction toward the pile head 101b).

[0174] By delivering fluid proximate the pile tip 101 a of the pile body 101, the fluid delivery device 110 may act to reduce the effective stress and / or resistance experienced by the pile body 101 as it is inserted into the seabed 5. In clays and soils that contain a significant proportion of clay and / or exhibit properties such as viscosity, the delivered fluid may particularly reduce the undrained shear strength at the soil / pile structure interface. This may reduce the driving force required to successfully install the pile structure 100 into the seabed 5, and therefore may reduce the amount of noise generated during installation relative to the size of the pile body 101 and / or allow for the use of smaller pile driving hammers. Conversely, because less energy is required to drive the pile structure 100 into the seabed 5, a larger pile structure 100 may be installed into the seabed 5 relative to the pile driving force.

[0175] The fluid delivery device 110 may act to reduce the effective stresses and / or resistance forces experienced by the pile body 101 as it is inserted into the seabed 5 by a number of mechanisms.

[0176] For example, the delivered fluid may act to lubricate the surface of the pile body 101, which may reduce the frictional forces experienced by the pile body 101 as it is inserted into the seabed 5.

[0177] Additionally, the delivered fluid may act to reduce effective stresses in the various soils 3, 4 of the seabed 5 that may resist penetration of the pile tip 101a.

[0178] For example, soil layers containing clay may exhibit high effective stress. Delivery of fluid to these clays may cause the clay and fluid to mix, further plasticizing the clay beyond its reformed shear strength, thereby potentially providing less resistance to insertion of the pile body 101. Additionally, the plasticized clay with increased water content may form a lubricating layer on the surface of the pile body 101, thereby reducing the frictional forces experienced by the pile body 101 as it is inserted into the seabed 5.

[0179] Similar to clay-containing soil layers, glauconite-containing soil layers (e.g., glauconite sand) may also exhibit high resistance to the penetration of the pile tip 101a into the seabed 5. Glauconite, like some clays, may respond to the insertion of an object (such as the pile tip 101a of the pile body 101) by generating negative pore water pressure. This negative pore pressure occurs as a result of the low permeability of the sediment and increases the shear strength of the sediment. By adding fluid to the sediment during insertion of the pile body 101, the negative pore pressure of the material can approach or become positive (i.e., exhibiting over-pore pressure), reducing the shear strength of the sediment. This can reduce the driving force required to insert the pile body 101 into such soil layers. Such high negative pore pressure regions also tend to occur near the pile body (e.g., within a few centimeters of the pile body), so delivering fluid to the surface of the pile body reduces the shear strength of these soil layers.

[0180] Also, by delivering the fluid in a direction away from the pile tip 101a, the fluid can be more efficiently applied to and lubricated on the surface of the pile body 101. Furthermore, by delivering the fluid in a direction opposite to the insertion direction of the pile structure 100, the possibility that the delivery of the fluid from the fluid delivery device 110 will be obstructed by the soils 3 and 4 on the seabed 5 is reduced.

[0181] In this embodiment, seawater is used as the fluid. However, in other embodiments, fresh water or bentonite mud may be used as the fluid. When water is used as the fluid, the fluid delivery device may be considered a "water" delivery device.

[0182] In this embodiment, the fluid is delivered from the fluid delivery device 110 at a pressure differential of 0-5 bar (0-500 kPa) compared to the pressure at sea level or at the pile tip 101a. However, in other embodiments, the fluid may be delivered at a pressure of 0-8 bar (0-800 kPa) or 0-3 bar (0-300 kPa). The use of low pressure (i.e., pressures less than 10 bar (1 MPa), orders of magnitude lower than the pressures used in processes such as jetting) allows the fluid to be delivered to the surface of the pile body 101 during insertion of the pile structure 100 without disturbing the surrounding soil.

[0183] For example, in the case of a pile structure 100 having a pile body 101 with a diameter of about 1.5 m, the volume of fluid delivered per hour is about 2 m 3 This value may vary depending on the size of the pile body 101 and the shape of the fluid delivery device. However, typically the volume of fluid delivered by the fluid delivery device 110 is between 0 and 10 m per hour. 3 or at least to the same extent.

[0184] In this embodiment, as shown in detail in Figure 2, the fluid delivery device 110 is positioned substantially at and directly behind the pile tip 101a of the pile body 101. The pile tip 101a of the pile body 101 may experience the greatest resistance during driving of the pile body 101, and therefore positioning the fluid delivery device 110 at the pile tip 101a may have the greatest effect in reducing the frictional forces / effective stresses experienced during insertion.

[0185] The fluid delivery device 110 comprises a manifold 103, which is an annular manifold extending circumferentially relative to the pile body 101. The manifold 103 is arranged to lubricate the outer surface of the pile body 101 and thus extends circumferentially around the pile body 101. The manifold 103 defines a plenum 104 arranged to receive seawater and a number of apertures 105 distributed around the periphery of the manifold 103 for delivering the seawater. Each aperture 105 can be considered a nozzle insofar as it directs the flow of fluid.

[0186] The multiple apertures 105 are holes or outlets located on the proximal-facing surface of the manifold 103 (i.e., the surface of the manifold 103 that faces the pile head 101b and faces in the opposite direction to the direction in which the pile body 101 is inserted into the seabed 5). Thus, the apertures 105 deliver water in the direction in which they face, as shown by the arrows in Figure 2. By arranging the multiple apertures 105 on the proximal (i.e., upper) surface of the manifold 103, water can be delivered to the outer surface of the pile body 101 more efficiently.

[0187] The manifold 103 is positioned aft of (i.e., adjacent and proximate to) and in contact with (i.e., immediately aft of) the external driving shoe 102a. In this manner, the driving shoe 102a protects the fluid delivery device 110 and reduces the likelihood of the fluid delivery device being sheared off during insertion of the pile body 101 into the seabed 5. Locating the manifold 103 immediately aft of the external driving shoe 102a ensures that the fluid delivery device 110 is positioned close to the pile toe 101a for most efficient delivery of fluid to the surface of the pile body 101.

[0188] 1 and 2, the fluid delivery device 110 is in fluid communication with a conduit 106 for delivering fluid to the fluid delivery device 110. In this embodiment, the conduit is a pipe 106. In this embodiment, the pipe 106 extends along the inner surface of the pipe body 101 and is in fluid communication with the plenum 104 via a channel 107 formed through the pipe body 101.

[0189] The pipe 106 extends from the fluid delivery device 110 to above the seabed 5 and is positioned such that when the pile structure 100 is installed at a desired depth within the seabed 5, the opening of the pipe 106 remains above the seabed 5. The opening of the pipe 106 is preferably located at least 2 m above the seabed 5. Thus, during insertion of the pile body 101 into the seabed 5, the opening of the pipe 106 remains clear of sediments on the seabed 5 that are stirred up and dispersed in the water flowing into the pipe 106, and therefore is not obstructed by the sediments.

[0190] The pipe 106 is located aft of the inner driving shoe 102b, which therefore protects the pipe 106 during insertion of the pile structure 100 into the seabed 5 in a similar manner to the outer driving shoe 102a in relation to the manifold 103.

[0191] Figure 3 shows a plan view of the pile structure 100. A cross section (i.e., Detail A) of Figure 2 is shown at line A-A'. The pile structure 100 comprises four pipes 106. Each pipe 106 is identical in function and structure to the pipes 106 described above. Although four pipes 106 are shown, any other suitable number of pipes 106 may be used to provide fluid flow to the fluid delivery device 110.

[0192] A number of apertures 105 are distributed circumferentially around the pile body 101 on the upper surface of the manifold 103 (i.e., on the surface facing the pile head 101b). The apertures 105 are uniformly distributed and spaced 30 mm apart, although other spacing arrangements are contemplated in other embodiments. Each aperture 105 has a diameter of 2 mm.

[0193] Figure 4 shows another embodiment of the present invention. In contrast to the embodiment shown in Figures 1, 2 and 3, the embodiment shown in Figure 4 includes both the external manifold 103 and the internal manifold 113 described above.

[0194] Like the outer manifold 103, the inner manifold 113 includes a number of apertures 115. The apertures 105 are uniformly distributed at intervals of approximately 5 mm. However, in other embodiments, intervals of 20 mm to 50 mm or other intervals are contemplated. Each aperture 105 has a diameter of approximately 2 mm.

[0195] FIG. 5 shows a cross-sectional view of the pile body 101, taken across line B-B' in FIG. 4, toward the pile tip 101a. The pipe 106 extends along the inner surface of the pile body 101 and is in fluid communication with a plenum 114 defined by an internal manifold 113. The internal manifold 113 is in fluid communication with the external manifold 114 via channels 107 formed through the pile body 107. The channels 107 are intermittently formed circumferentially around the pile body 101, preferably aligned with the pipe 106. However, additional channels 107 may be provided to further facilitate fluid flow from the plenum 114 of the internal manifold 113 to the plenum 104 of the external manifold 103. The channels 107 are preferably equally spaced around the circumference of the fluid delivery device 110.

[0196] Figure 6 shows a cross-sectional view of the pile body 101 towards the pile tip 101a, taken across line C-C' in Figure 4. Plenums 104, 114 defined by the external manifold 103 and the internal manifold 113, respectively, extend circumferentially relative to the pile body 101. The external manifold 103 and its plenum 104 extend circumferentially around the pile body 101, while the internal manifold 113 and its plenum 114 extend circumferentially within the pile body 101.

[0197] The multiple apertures 115 of the internal manifold 113, like the external manifold 103, are holes or outlets located on the proximally facing surface of the internal manifold 113. Thus, the apertures 115 deliver water in the direction they face, as shown by the arrows in Figure 6. By locating the multiple apertures 115 on the proximal surface of the internal manifold 113, water can be delivered more efficiently to the inner surface of the pile body 101.

[0198] The internal manifold 113 is disposed behind the internal driving shoe 102b and is in contact with the internal driving shoe 102b. Therefore, the internal manifold 113 and the pipe 106 connected to the internal manifold 113 are protected by the internal driving shoe 102b when the pile body 101 is inserted into the seabed 5.

[0199] In various embodiments, the pile structure 100 may include only the internal manifold 113 , only the external manifold 103 , or both the external manifold 103 and the internal manifold 113 .

[0200] Figure 7 shows a plan view of an alternative pile structure 100. Rather than having multiple apertures distributed circumferentially around the manifold 103, as is the case with the pile structure 100 shown in Figures 3 and 4, the pile structure 100 instead has one continuous aperture extending circumferentially around the manifold 103. Figure 9 shows a cross-sectional view of the pile structure 100 along line D-D'.

[0201] Figure 8 shows another plan view of another pile structure 100. The pile structure 100 includes both an outer manifold 103 and an inner manifold 113, each with one continuous aperture extending circumferentially around its periphery. Figure 9 shows a cross-sectional view of the pile structure 100 along line E-E', and a cross-sectional view of the pile structure along line F-F' is provided in Figure 10.

[0202] Figure 9 shows a cross-sectional view of the pile body 101 looking towards the pile tip 101a. The structure of the pile body 101 and fluid delivery device 110 is similar to that of Figure 5, so a discussion of similar features will not be repeated.

[0203] The fluid delivery device 110 comprises a single continuous aperture extending circumferentially around the manifold 103. This aperture can be equivalent to a slit or channel. This single continuous aperture is formed in the upper surface of the manifold 103 and is configured to deliver fluid from the plenum 104 of the manifold 103 to the surface of the pile body 101. This single continuous aperture has a depth of approximately 2 mm. In other embodiments, depths between 2 and 50 mm are contemplated.

[0204] By providing a single continuous aperture circumferentially around the wall of the pile structure 101, fluid can be more uniformly and completely delivered to the surface of the pile body 101 adjacent the pile tip 101 a. This arrangement may promote lubrication of the surface of the pile body 101.

[0205] A filter 108 is provided in the single continuous aperture to prevent soil from entering the manifold 103 through the single continuous aperture. The filter 108 is permeable to fluids, allowing fluids such as water to be delivered from the plenum 104 of the manifold 103 to the surface of the pile body 101 proximate the pile tip 101 a, but is impermeable to soil and other particulate matter above a predetermined particle size. This may prevent the single continuous aperture of the manifold 103 and the plenum 104 from becoming blocked or clogged during use.

[0206] 7 and described above, the fluid delivery device 110 includes an internal manifold 113. A plenum 114 of the internal manifold 113 is in fluid communication with the pipes 106 and therefore receives the fluid. A channel 107 is provided in line with the pipes 106 and supplies the fluid to the external manifold 103. In this embodiment, the channel 107 is also provided at a location between the pipes 106. However, in other embodiments, the fluid delivery device 110 may not include an internal manifold 113, and instead may include one or more pipes 106 that supply fluid to the external manifold 104 directly or indirectly via the channel 107.

[0207] The internal manifold 113 in this embodiment does not have apertures for delivering fluid to the inner surface of the pile body 101. Instead, the internal manifold 113 may function to regulate the flow of fluid to the external manifold 103. That is, by using the internal manifold 113 to receive the fluid and multiple channels 107 evenly distributed around the circumference of the fluid delivery device 110, a more even distribution of fluid to the external manifold 103 is achieved, resulting in a more even delivery of fluid from a single continuous aperture in the external manifold to the surface of the pile body 101 proximate the pile tip 101 a.

[0208] Figure 10 shows a cross-sectional view of the pile structure 100 of Figure 8, with the fluid delivery device 110 comprising an outer manifold 103 and an inner manifold 113. The structure of the pile body 101 and the fluid delivery device 110 is similar to that of Figure 6, and therefore a discussion of similar features will not be repeated.

[0209] The internal manifold 113 similarly includes a single continuous aperture configured to deliver water to the inner surface of the pile body 101 adjacent the pile tip 104a. This single continuous aperture is provided with a filter 118 having the same function and structure as the filter 108 provided in the external manifold 103.

[0210] 8, pipe 106 supplies fluid to fluid delivery device 110. Pipe 106 is in fluid communication with internal manifold 113 and may be aligned with a single continuous aperture in internal manifold 113. In an alternative embodiment, pipe 106 may intersect the single continuous aperture and be in direct fluid communication with plenum 114 of internal manifold 113.

[0211] The filters 108, 118 are sand-epoxy filters, although other filters are contemplated, such as Vyon filters, geotextile filters, etc. The permeability of the filter is selected depending on the selected pressure for delivering the fluid and the desired flow rate of the fluid from the fluid delivery device 110.

[0212] 11 shows a plan view of an alternative pile structure 100. The fluid delivery device 110 includes an internal manifold 113 defining a plenum 114 in fluid communication with the pipes 106. Fluid is supplied from the pipes 106 to the plenum 104 of the external manifold 103 via channels 107 extending through the pile body 101. In this embodiment, there are four pipes 106 and four channels 107 that supply fluid to the external manifold 103. However, in other embodiments, the fluid delivery device 110 may not include an internal manifold 113, but instead may include one or more pipes 106 that supply fluid to the external manifold 104 directly or indirectly via channels 107. The external manifold 103 includes a filter 109. The filter 109 is located downstream of the aperture 105 and extends circumferentially around the pile body 101.

[0213] Figure 12 shows a cross-sectional view of the pile structure 100 of Figure 11 taken along line G-G'. The external manifold 103 includes a single continuous aperture 105 configured to deliver fluid to the surface of the pile body 101 proximate the pile tip 101a. However, in other embodiments, the external manifold can include multiple apertures instead of a single continuous aperture. A filter 109 is provided in fluid communication with the aperture 105.

[0214] The filter 109 extends along the surface of the pile body 101 and has a sloped or tapered profile relative to the surface of the pile body 101. In this embodiment, the filter 109 is fixed and therefore extends between the outer edge of the manifold 104 and the surface of the pile body 101 proximate the pile tip 101a. In other embodiments, the filter 109 may be fixed anywhere on the manifold 103, such that the aperture 105 is located between the filter 109 and the surface of the pile body 101.

[0215] The filter 109 may facilitate delivery of fluid to the surface of the pile body 101 by directing the flow of fluid along the surface of the pile body 101 and by wicking the flow of fluid along the surface of the pile body 101. When the filter 109 is secured between the manifold 104 and the surface of the pile body 101, the filter 109 may prevent soil or other particles above a predetermined size from entering the fluid delivery device 110.

[0216] Additionally, the filter 109 may facilitate fluid delivery to the soil at the surface of the pile body 101 adjacent the pile toe 101 a. During insertion of the pile structure 100, due to the shape of the driving shoe 102 a, a cavity or soil overhang may be formed above the pile driving shoe 102 a that may initially fill with air or, if below the water table, with water. The filter 109 may improve contact between the pile structure 100 and the adjacent soil, ensuring that fluid is effectively delivered to the interface between the soil and the pile structure 100, particularly in the area of ​​the surface of the pile body 101 adjacent the pile toe 101 a.

[0217] The filter 109 is a geotextile filter and is attached to the pile structure 100 using glue. In other embodiments, the filter 109 may instead be a Vyon filter or a sand-epoxy filter and / or may be attached using a steel structure by welding and / or glue.

[0218] In this embodiment, the filter 109 is sheet-like or narrow. In other embodiments, the filter 109 may include a tapered cross section and may be placed flush with both the surface of the pile body 101 and the top surface of the manifold 103, i.e., against the aperture 105.

[0219] Figure 13 shows a plan view of an alternative pile structure 100. The pile structure 100 is similar to that shown in Figure 11 except that in addition to the filter 109 provided in fluid communication with the external manifold 104, a filter 119 is provided in fluid communication with the internal manifold 113.

[0220] Figure 14 shows a cross-sectional view of the pile structure 100 of Figure 13 taken along line H-H'. The pipe 106 extends through the filter 119 and through a single continuous aperture to deliver fluid to the plenum 114 of the internal manifold 113.

[0221] Figure 15 shows a cross-sectional view of the pile structure 100 of Figure 13 taken along line I-I'. The filters 109, 119 are each configured to deliver a fluid to the surface of the pile body 101. The structure and function of the filters 109, 119 are similar to that of the filter of Figure 12, and therefore a discussion of similar features will not be repeated.

[0222] As shown in Figures 14 and 15, respectively, the manifolds 103, 113 each include a transition portion 103a, 113a extending along the pile body 101 and positioned between the apertures 105, 115 and the pile body 101. The transition portion 103a, 113a may serve to facilitate fluid delivery from the apertures 105, 115 to the adjacent surface of the pile body 101. In this embodiment, the transition portion 103a, 113a has a tapered cross-section and defines a chamfer. In other embodiments, the transition portion 103a, 113a may have an alternative cross-section and may define a slope to direct water toward the surface of the pile body 101, or may define a fillet (i.e., a concave transition at an interior corner) or a bevel extending along the pile body. The transition portion 103a, 113a may also be employed in other embodiments.

[0223] Figures 16 and 17 show cross-sectional views of an alternative fluid delivery device 110. Figure 16 represents a cross-sectional view of the pile structure 100 of Figure 13 along line H-H', and Figure 17 represents a cross-sectional view of the pile structure 100 of Figure 13 along line I-I'.

[0224] In this embodiment, the filters 109, 119 are fixed to the external manifold 104 and the internal manifold 113, respectively. The filters 109, 119 are elongated in cross section, extend circumferentially around the pile body 101, and are fixed to the fluid delivery device 110 at only one end, which is adjacent to the manifolds 103, 113. Thus, the filters 109, 119 can be considered to have a fixed end and a free end. In this embodiment, the free end is not fixed to the surface of the pile body 101 at all. However, in other embodiments, the free end can be fixed to the surface of the pile body 101 periodically or intermittently, for example, every 10 cm or 20 cm.

[0225] The filters 109, 119 are geotextile filters and are therefore deformable. In use, the filters 109, 119 flap in a direction opposite to the insertion direction of the pile body 101, thereby acting as a skirt or collar for the fluid delivery device 110 which extends from the manifolds 103, 113 in a direction opposite to the insertion direction of the pile body 101. The apertures 105, 115 are located between the pile body 101 and the respective filters 109, 119.

[0226] The filters 109, 119 function to direct the fluid in a desired flow direction, thereby promoting fluid flow along the surface of the pile body 101. The filters 109, 119 may also function to increase the surface area of ​​contact between the fluid delivery device 110 and the surrounding soil during insertion, for example, if an overhang forms behind the driving shoe 102 that defines an air gap or water pocket.

[0227] Although the embodiments shown in each of Figures 14 to 17 do not include filters 108, 118 occupying apertures 105, 115, in other embodiments, filters 108, 118 occupying apertures 105, 115 may be provided in combination with filters 109, 119 extending from manifolds 103, 113.

[0228] As shown in FIG. 16, the pipe 106 passes between the internal filter 119 and the pile body 101 and intersects with the plenum 114 of the internal manifold 113 .

[0229] According to the embodiment described above, and referring again to FIG. 1, the pipe 106 is located internal to the pile body 101 and extends along the inner surface of the pile body 101 from the fluid delivery device 110 to above the seabed 106.

[0230] Opening 106a of pipe 106 communicates with a body of seawater 6 located inside pile body 101 to deliver water to fluid delivery device 110. The level of seawater 6 within pile body 101 is artificially raised (e.g., via a pump) relative to the water level 1 of ocean 2, and the hydrostatic head in the body of water forces the fluid through pipe 106 and through fluid delivery device 110 to the soils 3, 4 on the seabed 5. The level of seawater 6 within pile body 101 can be between 5 and 20 meters above sea level 1. For every 10 meters of rise in seawater 6 located within pile body 101 relative to sea level 1, the hydrostatic pressure in the body of water 6 can increase by approximately 1 bar (100 kPa). Therefore, the hydrostatic head of the seawater 6 in fluid communication with the opening 106a of the pipe 106 can create a greater pressure differential across the fluid delivery device 110, which causes fluid to move through the pipe 106 and the fluid delivery device 110 and be delivered to the soil 4 of the seabed 5.

[0231] The fluid delivery arrangement described above can be particularly effective in delivering fluid to soils that generate negative pore water pressure in response to the insertion of a foreign object. An example of such a soil is, as mentioned above, a glauconite-containing soil. When the pore water pressure is negative, the soil acts like a sponge and readily accepts the delivered water. (Some glauconite samples have been found to have negative pore water pressures on the order of up to 20-40 bar (2-4 MPa), and accordingly, an effective pressure differential can consistently drive fluid through the fluid delivery device 110 into such soil.) In doing so, the soil's pore water pressure approaches positive, reducing its shear strength. Therefore, less energy is required to drive the pile tip 101a into the soil, making its insertion easier.

[0232] The above-described fluid delivery arrangement is also particularly advantageous in that, after artificially raising the water level in the body of water 6, no further energy is required to push the fluid through the fluid delivery device 110. Therefore, this fluid delivery arrangement can be considered a passive fluid delivery arrangement or a passive mode of operation. The fluid delivery by the fluid delivery device 110 requires only a low pressure sufficient to lubricate the surface of the pile body 101, and therefore, high-pressure pumping equipment is not required for some soils. Therefore, the potential energy of the body of water 6 is sufficient to move the fluid through the fluid delivery device 110.

[0233] In an alternative fluid delivery arrangement, the opening 106a of the pipe 106 is in fluid communication with a pump 120. Figure 18 shows the pile structure 100 in a configuration in which fluid is pushed through the fluid delivery device 110 by the pump 120. The pump 120 is in fluid communication with the pipe 106 via a hose or other suitable pipe that passes through a hatch 101c formed in the wall of the pile body 101.

[0234] Pump 120 is a submersible pump suspended from a vessel (not shown) located at the sea surface 1. In another embodiment, pump 120 is located on the vessel and arranged to pump fluid from the vessel.

[0235] The pump 120 is controlled to vary the pressure of the fluid delivered by the fluid delivery device 120. For example, in soils that experience negative pore water pressure, a lower water pressure is sufficient to deliver fluid through the fluid delivery device 110.

[0236] Soils with high effective stress, such as those containing high-strength clays, may require a greater differential pressure to deliver water to the soil (e.g., to generate excess pore water pressure). As previously discussed, delivering fluid to the clay in this manner may result in mixing of the clay with the fluid, plasticizing the clay and reducing resistance to insertion of the pile body 101. Thus, the use of pump 120 may assist in moving fluid through fluid delivery device 110 so that the fluid is properly delivered to soils with high effective stress. This fluid delivery arrangement may therefore be referred to as an active fluid delivery arrangement or active mode of operation.

[0237] The hatch 101c can be opened when necessary and also functions as a service hatch formed in the wall of the pile body 101. When closed, the hatch 101c is fluid-tight. In the arrangement shown in Figure 1, the hatch 101c is closed. In the present arrangement shown in Figure 18, the hatch 101c is open. Thus, the pile structure 100 can be arranged to operate in either a passive or an active mode of operation, depending on the characteristics of the soils 3, 4 of the seabed 5 at the desired installation location of the pile structure 100.

[0238] For each of the fluid delivery arrangements described above, the pressure of the delivered fluid is similar to the order of the hydrostatic pressure of the sea 2 at the installation location of the pile structure 100. For example, a pressure of 0-5 bar can be used to effectively deliver fluid from the fluid delivery device 110. This contrasts with the much higher differential pressures used in processes such as jetting, which may require differential pressures on the order of 10-100 bar (1 MPa-10 MPa) to achieve the desired liquefaction / displacement of soil from the seabed.

[0239] By providing lubrication to the pile body 101 with a low differential pressure, disturbance of the soils 3, 4 on the seabed 5 can be suppressed when the pile body 101 is inserted into the seabed 5. Therefore, when the pile structure 100 is installed, the seabed 5 can provide better lateral support to the pile structure 100, which may result in improved stability of the facility.

[0240] In various embodiments, the pipes 106 may extend along the exterior of the pipe body 101. The pipes 106 may be protected by the external driving shoe 102a, as described above. The pipes 106 may be in fluid communication with the internal manifold 113 via respective channels 107 formed through the pile body 101, or may be provided in fluid communication with the plenum 104 of the external manifold 103. When the pipes 106 are external to the pile body 101, they are configured for use in combination with the pump 120. The remaining structural and functional features of the pile structure 100 are as described above.

[0241] While the pile structure 100 shown in Figures 1-7 is a single pile structure, alternative pile structures are also consistent with the present invention. For example, Figure 19 shows a foundation structure 200 for an offshore wind turbine installed on the seabed 5. The foundation structure 200 includes a jacket structure 201 having multiple legs 202 and multiple pile structures 300. Each leg 202 is attached to a respective pile structure 300. The jacket structure 201 is a lattice structure located above the seabed 5. The wind turbine can be attached to a mounting surface 203 of the jacket structure 201, which is located above sea level 1. Each pile structure 300 has a structure similar to the pile structure 100 described above. In a preferred embodiment, each pile structure 300 includes an internal manifold and pipes extending therethrough. The structure of these components is as described above.

[0242] Although the embodiments described herein relate to pile structures having tubular pile bodies of circular cross section, the fluid delivery device of the above-described function and configuration can be modified for use in pile structures having pile bodies of different shapes and sizes.

Claims

1. Pile structures, A pile body having a pile tip configured to be inserted into the ground, The system includes a fluid delivery device configured to deliver fluid to the surface of the pile body adjacent to the pile tip in a direction away from the pile tip, The fluid delivery device is configured to deliver the fluid with a local differential pressure between 0 and 8 bar. Pile structure.

2. The pile structure according to claim 1, wherein the fluid delivery device is configured to deliver the fluid at a local differential pressure between 0 and 5 bar.

3. The pile structure according to claim 1, wherein the fluid delivery device comprises a manifold having one or more apertures configured to deliver the fluid.

4. The pile structure according to claim 3, wherein the one or more apertures comprise a single continuous aperture extending around the pile body.

5. The pile structure according to claim 3, wherein the fluid delivery device comprises one or more first filters occupying one or more apertures, and the one or more first filters are configured to be impermeable to soil.

6. The pile body is a tubular pile body, and the manifold is an annular member that defines a plenum extending circumferentially with respect to the pile body, The manifold is configured to receive the fluid flow through a channel formed through the pile body, The manifold includes a transition portion that extends along the pile body in a direction away from the pile tip. A pile structure according to claim 3, which is at least one of the following.

7. The fluid delivery device includes a second filter configured to extend from the manifold in a direction opposite to the insertion direction of the pile tip, The second filter is permeable to the fluid. The pile structure according to claim 3.

8. The second filter is a geotextile fabric filter defining a skirt extending from the manifold, and the one or more apertures are located between the skirt and the pile body, The pile structure according to claim 7, wherein the second filter defines a sloped surface extending between the manifold and the pile body, and the one or more apertures are covered by the second filter.

9. The pile structure according to claim 3, wherein the manifold extends around the outer surface of the pile body, and the one or more apertures are configured to deliver the fluid to the outer surface of the pile body.

10. The pile structure according to claim 3, wherein the manifold extends around the inner surface of the pile body, and the one or more apertures are configured to deliver the fluid to the inner surface of the pile body.

11. The manifold is a first manifold having a first set of one or more apertures, and the fluid delivery device comprises a second manifold having a second set of one or more apertures configured to deliver the fluid. The pile structure according to claim 9, wherein the second manifold extends around the inner surface of the pile body, and the second set of one or more apertures is configured to deliver the fluid to the inner surface of the pile body.

12. The pile structure according to claim 1, further comprising a driving shoe positioned at the tip of the pile, wherein the fluid delivery device is selectively positioned behind the driving shoe and in contact with the driving shoe.

13. The pile structure according to claim 1, further comprising a conduit extending along the surface of the pile body, wherein the conduit is configured to provide the flow of the fluid to the fluid delivery device.

14. The pile structure according to claim 13, wherein the conduit extends along the inner surface of the pile body.

15. The pile structure according to claim 14, wherein the conduit is configured to be used in a passive operating mode, in which the conduit is in fluid communication with a fluid region of the fluid located inside the pile body, and the hydrostatic pressure generated by the fluid region moves the flow of the fluid to the fluid delivery device.

16. The conduit is configured to be used in an active operating mode, and in the active operating mode, the conduit is in fluid communication with a pump arranged to move the flow of the fluid to the delivery device, and / or, The aforementioned conduit is positioned behind the drive shoe, and / or, The pile structure according to claim 13, comprising a number of the aforementioned conduits.

17. The aforementioned pile body is a tubular pile body, and / or, The pile structure according to claim 1, wherein the ground is the seabed.

18. The pile structure according to claim 1, wherein the offshore pile structure is an offshore single pile structure.

19. A jacket structure with numerous legs, A plurality of pile structures according to any one of claims 1 to 17, Each leg of the aforementioned jacket is attached to the respective pile structure. Foundation structure.

20. An offshore wind turbine structure comprising a wind turbine attached to a pile structure according to claim 18.

21. A system for installing pile structures within the ground, A pile structure according to any one of claims 1 to 18, Pile driving hammer and A system equipped with these features.

22. A method for installing pile structures within the ground, The process involves driving the tip of the pile body into the ground using a pile driving tool, To deliver fluid to the surface of the pile body adjacent to the tip, The fluid is delivered in a direction away from the tip of the pile, The fluid is delivered with a local differential pressure between 0 and 8 bar. A method that includes this.

23. The method according to claim 22, wherein the pile structure is the pile structure described in any one of claims 1 to 18.

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