Method for storing large tubular piles

Abstract

Method of storing one or more tubular structural piles (1), such as a pin pile or monopile, in a horizontally lying state above a supporting surface (2), in particular a ground surface, wherein the method comprises the steps of: • - providing, on the supporting surface, a seating arrangement (30) comprising one or more seating members (3) arranged along a longitudinal axis for receiving and holding the tubular structural pile in the horizontally lying state therein at a non-zero distance from said supporting surface; • - positioning the tubular structural pile (1) in the horizontally lying state in the one or more seating members of the seating arrangement such that a center of gravity of the tubular structural pile is positioned in between longitudinal outer ends of the seating arrangement and such that the central longitudinal axis is substantially parallel to the longitudinal axis; characterized in that the step of providing the one or more seating members of the seating arrangement comprises the steps of: • - providing a plurality of supporting bodies (31-36), wherein a supporting body is formed from a flexible container comprising a filling of a loose granular substance, such as sand; • - positioning the supporting bodies for forming the one or more seating members.

Description

[0001] The present invention relates to a method of storing one or more tubular structural piles, such as a pin pile or monopile, in a horizontally lying state at a spaced apart distance from a supporting surface. The present invention further relates to a seating member, a pile positioning device and a spreader lifting beam for use in the method of storing.

[0002] In order to be able to operate wind turbines offshore, offshore foundations are required for anchoring the wind turbines to the seabed and for raising the towers of such wind turbines sufficiently high to not be impacted by sea waves. Although various types of offshore foundation structures exist, the monopile is still the most common type. A monopile is essentially a large tubular pile (i.e. having a diameter of at least 4 meters, nowadays typically 7 meters or more, and 10 meters or more is already planned for) that is driven into the seabed. Different types of bottom-fixed offshore foundations are multi-membered lattice type foundations, such tripods and / or jacket foundations. These types of foundation are typically anchored to the seabed using so called pin piles (e.g. having a diameter in between 1 to 4 meters), which are long and slender tubular piles that are piled into the seabed for anchoring the multi-membered lattice type foundations.

[0003] As offshore wind farms comprise many tens, or even more than a hundred, turbines, a typical wind farm requires as many foundations, thereby resulting in large numbers of monopiles and / or pin piles that are manufactured and subsequently stored in yard areas, typically a large plot of land in a harbor / port area having a quayside (nearby), from whereon they are loaded onto installation and / or transport vessels. Such a yard area will therefore be arranged for storing, for a limited time, a large amount of these tubular structural piles. yard preparation is required as the piles needs to be stored at height (i.e. space apart from the ground surface) for pile integrity and to enable and accommodate the transport of piles, which is typically done by Self Propelled Modular Transporters (SPMTs) that can be positioned under the piles for subsequently lifting and transporting the piles. A typical monopile nowadays is around 8 meters in diameter and easily weights 1200 metric tons, while monopiles of over 3000 metric tons having diameters of more than 12 meters for future projects are also already planned for. At the same time, the piles are relatively thin-walled, such that an insufficient contact area during the storage can cause plastic deformation of the pile.

[0004] Yard areas are furthermore also not directly suitable for storing these monopiles. In case they would be simply laid onto a flat ground surface, an unallowable line loading exceeds the load bearing capacity of the ground surface. Traditionally, project-specific sand dunes are erected in the yard area, which, firstly require enormous volumes of sand (up to, or even over 30.000m 3< ) and secondly require to be formed in small layers that need to be compacted before depositing a next layer. Additionally, as the project-specific sand dunes are tailored towards a project-specific monopile (i.e. having a specific weight, diameter, length and / or geometry), they cannot simply be reused for a next project and need to be decommissioned after the monopiles have all been installed offshore. The enormous amounts of sand need to be disposed of, making the process unsustainable and time consuming. The commissioning and decommissioning of the sand dunes can take up to 10 weeks per project, which reduces the effective time a yard area can be used for storage purposes.

[0005] The goal of the present invention is therefore to provide for an improved method of storing one or more tubular structural piles, such as a pin pile or monopile, in a horizontally lying state at a spaced apart distance from a supporting surface, such as a ground surface, wherein at least some of the above presented issues have been resolved, or at least wherein the impact is reduced.

[0006] In a first aspect, the disclosure relates to a method of storing one or more tubular structural piles, such as a pin pile or monopile, in a horizontally lying state above a supporting surface, in particular a ground surface, wherein the method comprises the steps of: providing, on the supporting surface, a seating arrangement comprising one or more seating members arranged along a longitudinal axis for receiving and holding the tubular structural pile in the horizontally lying state therein at a non-zero distance from said supporting surface; positioning the tubular structural pile in the horizontally lying state in the one or more seating members of the seating arrangement such that a center of gravity of the tubular structural pile is positioned, as seen in a top down view and along a central longitudinal axis of the tubular structural pile, in between longitudinal outer ends of the seating arrangement and such that the central longitudinal axis is substantially parallel to the longitudinal axis; characterized in that the step of providing the one or more seating members of the seating arrangement comprises the steps of: providing a plurality of supporting bodies, wherein a supporting body is formed from a flexible container comprising a filling of a loose granular substance, such as sand; positioning the supporting bodies for forming the one or more seats.

[0007] The invention thereby distinguishes from the traditionally formed sand dunes in that the seating members, which together form the seating arrangement, are formed from arranging a plurality of supporting bodies that are formed from a flexible container (e.g. a bag) comprising a filling of a loose granular substance, such as sand (e.g. a sandbag), gravel, concrete granulate, plastic granulate, rubber granulate, granulates from waste sources, and / or a combination of these. It is further noted that "loose" defines that the granular substance is not bounded together using a hardening binding agent and / or other means for solidifying the granular substance (i.e. permanently affixing or adjoining the separate granulates for forming a solid body). The filling of loose granular substance may be compacted for obtaining desired mechanical characteristics of the supporting bodies. The supporting bodies preferably have a width and length (and preferably height) of more than 1 meters, for example being 2 meters in length and having a width of 1 meter. Preferably, the footprint (i.e. bottom) of the supporting bodies are quadrilaterals, more preferably substantially square and / or rectangular. Oval shaped footprints, e.g. round or ellipse shaped, may also be possible. These supporting bodies can thereby be placed, and later removed, using lifting equipment that is commonly available in a yard, such as a reach-stacker, forklift, telehandler, container handler, bulldozer or straddle carrier (which may all be modified for the purpose) or similar wheeled, or tracked, vehicles that can lift objects. This reduces the commissioning and decommissioning of the seating arrangement, such that the effective availability of the yard is increased. Additionally, the supporting bodies can be stored and reused for a next project, also in a separated state, wherein the filing of loose granular substance and the flexible containers are separately stored, resulting in a more sustainable process.

[0008] The supporting bodies can be held together using suitable means, for instance using tension straps that are arranged onto or around the supporting bodies, in order to absorb any traverse forces that the tubular structural pile exerts on the plurality of supporting bodies. In a preferred embodiment, the flexible containers comprise a reinforced bottom, such that they can be lifted in a filled state without tearing due to the self-weight of the supporting bodies. The method is highly suitable for storing piles having a diameter of at least 1 meter, preferably at least 4 meters, more preferably at least 6 meters.

[0009] The filling of the loose granular substance preferably comprises grain sizes, as defined on the Krumbein Phi Scale, in the range of 8 to -6 (which corresponds to a metric size range of 0.0625 mm to 64 mm), preferably in the range of 4 to -4 (equivalent to a sand and / or gravel; e.g. a very fine sand, fine sand, medium sand, coarse, very coarse sand, (very) fine gravel and / or medium gravel), more preferably in the range of 2 to -2 (equivalent to medium sand to very fine gravel). It is noted that the loose granular substance may comprise grains having different sizes and / or being from different materials. The loose granular substance may also have substantially the same size (range) and be made from a single (type of) material. Preferably, the loose granular substance, when graded using a coefficient of uniformity Cu, and preferably a coefficient of curvature Cc, has a Cu of at least 3, preferably at least 4 and, preferably, the Cc is between 0.5 and 5, more preferably between 1 and 3. The loose granular substance is preferably well-graded, as this will minimize settlement of the filling material.

[0010] In a preferred embodiment, the step of arranging the supporting bodies for forming the one or more seating members comprises forming a respective seating member by positioning a plurality of supporting bodies in a predefined pattern of adjacent supporting bodies, preferably wherein said predefined pattern extends in two different directions, as seen from a top-down view. Such a predefined pattern of adjacent supporting bodies thereby allows to spread the gravitational loading due to the weight of the tubular structural pile over a larger surface area, thereby reducing the pressure exerted onto the supporting surface, e.g. ground surface, of the yard. In dependence of the size and weight of the tubular structural pile, the specific pattern and the required amount of adjacently arranged supporting bodies can be selected and positioned. It is noted that adjacent supporting bodies may, or may not, directly abut each other.

[0011] It is then preferred that the predefined pattern comprises one or more traversely extending rows of adjacently positioned supporting bodies that extend along a traverse axis that is substantially perpendicular to the longitudinal axis, wherein a row comprises two or more, preferably three or more, more preferably four or more, adjacently positioned supporting bodies; and / or wherein the predefined pattern comprises one or more longitudinally extending columns, of adjacently positioned supporting bodies that extend along the longitudinal axis, wherein a column comprises two or more, preferably three or more, more preferably four or more, adjacently positioned supporting bodies. A substantially square and / or rectangular pattern comprising a number of rows, and preferably also comprising a number of columns, of supporting bodies is relatively easy to position on the supporting surface. Such a predefined pattern is best made using supporting bodies having a rectangular or square footprint, as a tight-packed arrangement is thereby enabled, leading to an effective distribution of the gravitational forces over a large surface.

[0012] Preferably, a respective seating member has a first traverse outer end, as seen along the traverse axis, that is higher than the average height of the seat, and, preferably, a second, opposite, traverse outer end that is higher than the average height of the seat; and / or wherein a respective seating member has a central section that is in between the respective outer traverse ends of the seat, wherein the central section has a lower height compared to the average height of the seat; and wherein the step of positioning the tubular structural pile comprises positioning the tubular structural pile such that, as seen in a top view along a vertical axis that is substantially perpendicular to the supporting surface, the central longitudinal axis is positioned in between the respective outer traverse ends of the seating member and / or is positioned in the central section of the seat.

[0013] By varying the height of the respective supporting elements, the outer contour of the tubular structural pile can be followed. This allows to create a relatively large contact surface between the pile and the respective seating member, point- and / or line loading is thereby prevented as much as possible, resulting in an even distribution of the contact forces. Additionally, this prevents the pile from easily rolling of the respective seating member. It is further noted that the filling degrees of the supporting bodies that are comprised in different seating members can be different, depending on the pile specifics and local loading conditions such as snow, ice and (storm) wind.

[0014] This advantage is for instance also achieved by an upper side of the cross-section of the seating member, as taken perpendicular to the longitudinal axis, approximates a substantially concave, U-, and / or V-shaped, wherein the approximate of the substantially concave, U-, and / or V-shape is a continuous or non-continuous shape, in particular wherein the non-continuous shape is a piecewise linear and / or stepwise concave, U-, and / or V-shape; and wherein the step of positioning the tubular structural pile comprises positioning the tubular structural pile such that, as seen in a top view along a vertical axis that is substantially perpendicular to the supporting surface, the central longitudinal axis is positioned in substantially central part of the substantially concave, U-, and / or V-shape. To maximize the above mentioned advantage, at least a portion of the upper side of the cross-section of the seating member is shaped, and preferably sized, to correspond to the outer circumferential shape, and preferably the size, of the structural tubular pile. This may also allow to accommodate any protruding parts of the tubular structural pile that protrude from the outer circumferential wall of the pile. It can be envisioned that some of the supporting bodies are given a decreased height for this.

[0015] Preferably, when a traversely extending row comprises at least three supporting bodies, the average height of the supporting body and / or bodies in a central section of the traversely extending row is lower than the average height of the supporting body and / or bodies in an outer end section of the traversely extending row, wherein said central section is in between the respective outer end sections. Hereby, the piecewise linear and / or stepwise concave, U-, and / or V-shape may be obtained in simple manner. The height of a supporting bodies may be adjusted by adding, removing and / or compacting filling of loose granular substance inside of the flexible container. The, preferably closed-off, flexible container may be re-openable for that purpose. The flexible container may therefore be fitted with a filling opening that is openable and resealable. The flexible containers of all the supporting bodies may therefore be identical, whereby the height difference is obtained through filling the flexible containers with different amounts of loose granular substance, and / or by different levels of compacting the loose granular substance held in the flexible containers.

[0016] In a preferred embodiment, the flexible container is formed from a flexible fabric, in particular a flexible high-tensile strength fabric such as a geotextile or fiber-reinforce polymer sheet, and wherein the flexible container is closed-off for retaining the filling of the loose granular substance therein. Geotextiles are highly suitable for holding loose granular substance therein, as inherent permeability allows excess water to drain from the flexible containers, while at the same time, geotextiles can be obtained with high-tensile strengths. It is thereby prevented that the loose granular substance is saturated with (rain-) water, while also enabling to obtain flexible containers strong enough, such that the supporting bodies may be lifted during the process of commissioning and / or decommissioning the yard area. An inner, and / or outer, lining of non-woven material, such as felt, that is arranged with the geotextile may prevent granular particles having a small size from permeating out of flexible containers.

[0017] Alternatively, or additionally, the flexible fabric may be a reinforced sheet of plastic material. Such a reinforced sheet of plastic material may be formed by arranging (e.g. welding) a plastic layer (e.g. elastomeric foil) onto, or around, a sheet formed from reinforcing fibers and / or wire material, such as for instance a nylon-wire, metal-wire (e.g. steel wire), glass-fiber, carbon-fiber basis. Alternatively, a woven sheet of fiber material may for instance be covered by a layer of an elastomeric material (through a casting process or the like). A sheet of plastic material is hereby obtained that is reinforced by the therein arranged internal fibers and / or wires.

[0018] In a preferred embodiment, the sheet of flexible material comprises a plurality of layers of flexible material. The layers are preferably interconnected by stitching said layers such that the plurality of stacked layers effectively acts as a single sheet of flexible material. By arranging the sheet as a stack of a plurality of different and / or the same layers, one is able to tune the permeability and / or tensile strength of the sheet of flexible material.

[0019] In a preferred embodiment, the flexible container is made from a sheet of fabric that comprises a plurality of layers of flexible material. The layers are, for instance, interconnected by stitching said layers such that the plurality of stacked layers effectively acts as a single sheet of flexible material. By arranging the sheet as a stack of a plurality of different and / or the same layers, one is able to tune the tensile strength of the sheet of flexible material.

[0020] In a certain embodiment, at least two layers of the plurality of layers have a higher tensile strength along a primary axis and a lower tensile strength along a secondary axis, and wherein the two layers of the plurality of layers are arranged such that the respective primary axis are at a non-zero angle, preferably at 90°, with respect to each other. As high-strength geotextiles typically have a bi-directional strength, wherein the tensile strength along a primary axis is higher than along a secondary, perpendicular, axis, a stacking of at least two layers, wherein the layers are arranged at a non-zero angle, in particular a 90° angle, allows to obtain a sheet of fabric, and thereby a flexible container, having an omnidirectional tensile strength.

[0021] The flexible fabric may also be non-permeable material, such as for instance a fiber-reinforce polymer sheet of polymer material, such as elastomers. Such a fiber-reinforce polymer sheet may be formed by arranging a polymer layer (e.g. foil) around a basis of reinforcing fiber material, such as for instance a nylon-wire basis, or a reinforcing metal-wire grid.

[0022] It is preferred that the flexible containers are made from a flexible fabric having a high-tensile strength of at least 500 kN / m, preferably at least 1000 kN / m, more preferably at least 1500 kN / m, to ensure the integrity of the flexible containers.

[0023] Preferably, a set of supporting bodies of the plurality of supporting bodies are interconnected and wherein the step of positioning the supporting bodies comprises simultaneously positioning the first set of supporting bodies. Multiple supporting bodies can thereby be lifted in a single lift, even further reducing the commissioning and decommissioning time.

[0024] It is then further preferred that the supporting bodies comprise a bottom that is positioned onto (i.e. arranged to face the) supporting surface during the step of positioning the supporting bodies and a top that is arranged to face the tubular structural pile; and wherein the supporting bodies forming a respective set are interconnected by means a bottom connecting member that interconnects the respective bottoms of the respective set, and / or by means a top connecting member that interconnects the respective tops of the respective set, and / or by means of a circumferential connecting members that connect side walls of the flexible containers of the supporting structure of the respective set. Such a bottom and / or top connecting member enables the interconnected members and, additionally, is able to (in case of an interconnected row) absorb the traverse forces that the monopile exerts onto the seating members. As these forces are self-balancing, the traverse forces that act on the first traverse outer end, are substantially equal and opposite to the traverse forces that act on the second, opposing, traverse outer end. There is thereby no need to anchor, or connect in any other way, the supporting members to the supporting surface.

[0025] Preferably, the set of interconnected supporting bodies are simultaneously positioned by simultaneously lifting the respective set by means of a movable lifting device, wherein a spreader lifting beam is arranged in between the lifting device and the set of interconnected supporting bodies, and wherein the spreader lifting beam comprises one or two hook-on points for connecting it to the lifting device and comprises a plurality of spaced apart suspension points for suspending the set of interconnected supporting bodies from the spreader lifting beam using a plurality of lifting cables and / or slings; and wherein the steps of providing and positioning the plurality of supporting bodies comprises: connecting the plurality of lifting cables to the set of interconnected supporting bodies; lifting and moving the interconnected supporting bodies using the movable lifting device to a designated location where a seating member of the seating arrangement is to be positioned; lowering and positioning the set interconnected supporting bodies onto the supporting surface according to the predefined pattern; disconnecting the plurality of lifting cables from the set of interconnected supporting bodies.

[0026] Multiple supporting bodies are thereby lifted in a single lift, for obtaining the reduction in commissioning and decommissioning time. The supporting bodies are not necessarily interconnected for simultaneously lifting the supporting bodies with the spreader lifting beam. In a further aspect, the disclosure also relates to a herein disclosed spreader lifting beam as such.

[0027] The spreader lifting beam preferably comprises two hook-on points at spaced apart outer longitudinal ends of the spreader lifting beams, preferably extending from a top side of the spreader lifting beam, such the spreader lifting beam may be suspended from a lifting device, such as reach-stacker, forklift, telehandler, bulldozer, container handler or straddle carrier (which may all be modified for the purpose), by means of a, or a pair of, lifting cable(s) and / or sling(s) that interconnect the respective hook-on points with the lifting device. The plurality of spaced apart suspension points are preferably arranged at a bottom side, that is substantially opposite from the top side, of the spreader lifting beam. In order to evenly distribute the load and to be able to suspend each supporting body of a set of interconnected supporting bodies, the spaced apart suspension points are preferably evenly spaced along the length of the spreader lifting beam.

[0028] In a preferred embodiment, the step of positioning the tubular structural pile comprises, by using a pile positioning system: lifting and moving the tubular structural pile in the horizontally lying state from a first position to the seating arrangement; lowering the tubular structural pile in the horizontally lying state into the one or more seating members of the seating arrangement. The piles can thereby be moved to the stored position.

[0029] It is then preferred that the pile positioning system comprises a pile holding device and a drivable transport system, in particular comprising a pair of multi-axle vehicles, wherein the pile holding device comprises a lifting frame and a lifting cradle, wherein the pile holding device is arranged onto the drivable transport system, such as (e.g. comprising a plurality of coupled) Self Propelled Modular Transporters (SPMTs), that are arranged to move over the supporting surface; wherein said lifting frame holds the lifting cradle for holding the tubular structural pile therein, wherein the lifting cradle is movable in the vertical direction for lifting and lowering the tubular structural pile with respect to the supporting surface. SPMTs are widely available, and suitable for use on a yard area. A highly suitable pile positioning system is thereby obtained that requires only some custom-made, or custom-purpose, components.

[0030] It Is preferred that the pair of multi-axle vehicles have a height-adjustable cargo platform, whereon the lifting frame is arranged (e.g. connected) on top of the height-adjustable cargo platform and wherein the steps of lifting and lowering of the tubular structural pile of comprise, respectively, increasing and decreasing the height of the height-adjustable cargo platform. Typical SPMTs comprise such height-adjustable cargo platforms, such that the lifting frame may be a simple rigid frame that is supported on the SPMTs, thereby leading to a very simple and robust lifting frame. Additionally, or alternatively it is then preferred that the lifting cradle is vertically movably with respect to the lifting frame and wherein the steps of lifting and lowering of the tubular structural pile of comprise, respectively, lowering and lifting the lifting cradle with respect to the lifting frame. In case the SPMTs do not comprise such height-adjustable cargo platform, or do not have the required vertical reach, the lifting cradle made be made vertically movably with respect to the lifting frame, for instance by means of a pair of vertically arranged hydraulic lifting cylinders.

[0031] Preferably, the lifting frame is substantially n-shaped having a pair of spaced apart column beam members that are interconnected by means of a girder beam member. A first column beam member of said column beam members may have a higher bending stiffness, for instance by means of a thereto connected diagonal beam, and / or lattice, structure, for increasing the stability of the lifting frame. The length of column beam members is greater than the diameter of the tubular structural pile and, preferably, wherein the column beam members are arranged at a mutual distance that is greater than the diameter of the tubular structural pile; preferably wherein the length of the girder beam member is adjustable for adjusting the spaced apart distance between the spaced apart column beam members; and preferably wherein the lifting cradle, that may be formed from a substantially limply arranged lifting sling and / or belt arrangement, is connected to the n-shaped lifting frame, in particular to the pair of spaced apart column beam members. The lifting cradle thereby acts as a support in the horizontal and vertical direction for the pile. The lifting cradle may be adjusted in length to accommodate piles having different diameters. Alternatively, the lifting cradle may hold multiple, smaller diameter (i.e. up to 4 meters), piles simultaneously. The n-shape (i.e. inverted U-shape and / or horseshoe-shape) enables the lifting frame to surround a stored tubular structural pile while being able to move in a direction substantially parallel to the central longitudinal axis of the tubular structural pile. The lifting cradle is for this purpose preferably detachable from at least on side of the lifting frame, such that the pile positioning system is able to also pass the seating arrangement wherein the tubular structural pile is stored in. In a further aspect, the disclosure also relates to a herein disclosed pile positioning system and / or a pile holding device as such.

[0032] It is preferred that in the step of positioning the tubular structural pile two pile positioning systems are used, wherein a first pile positioning device is arranged to lift the structural pile at a first lifting location that is in between the center of gravity and a first longitudinal outer end of the tubular structural pile; and wherein a second pile positioning device is arranged to lift the structural pile at a second lifting location that is in between the center of gravity and a second longitudinal outer end, that is opposite to the first longitudinal outer end, of the tubular structural pile. The pile is thereby stably held by the two pile positioning systems during lifting and transporting. Due to the movability of the positioning systems in all different directions, the piles can be tightly packed on the yard area.

[0033] Preferably, the method comprises storing a second tubular structural pile, such as a pin pile or monopile, in a horizontally lying state above a supporting surface, wherein the second tubular structural pile is positioned in a second seating arrangement, preferably substantially similar to the seating arrangement, to be stored substantially parallel to the tubular structural pile. It is then preferred that a distance between the respective piles is larger than the size, i.e. width, of the smallest column of the lifting frame (i.e. having the lowest stiffness) and preferably no more than 10 times the width of the column, more preferably no more than 5 times, most preferably no more than 3 times. The pile positioning systems are thereby able to move between, and along, the respective stored tubular structural piles, while at the same time allowing for storing a high number of tubular structural piles on the yard are. Hence, the method preferably comprises storing a plurality of tubular structural piles (e.g. 5 or more, 10 or more, 20 or more).

[0034] In a second aspect, the disclosure relates to a seating member for use in the method according to any of the preceding embodiments of the first aspect, wherein the seating member comprises a plurality of supporting bodies that comprises a flexible container comprising a filling of a loose granular substance, such as sand; wherein the plurality of supporting bodies are arranged in a predefined pattern of adjacent supporting bodies; and, preferably, wherein a set of a part of, or all of, the supporting bodies of the plurality of supporting bodies that form the seating member are interconnected. The seating member is thereby suited for forming the seating arrangement as previously described.

[0035] As was described above, it is preferred the flexible container is formed from a flexible fabric, in particular a flexible high-tensile strength fabric such as a geotextile or a fiber-reinforce polymer sheet, and wherein the flexible container is closed-off for retaining the filling of the loose granular substance therein; and / or wherein the supporting bodies comprise a bottom that is arranged to face the supporting surface and a top that is arranged to face the tubular structural pile; and wherein the supporting bodies forming the set are interconnected by means a bottom connecting member that interconnects the respective bottoms of the respective set and / or by means a top connecting member that interconnects the respective tops of the respective set, and / or by means of a circumferential connecting members that connect side walls of the flexible containers of the supporting structure of the respective set.

[0036] The present invention is further illustrated by the following figures, which show preferred embodiments of the different aspects of the present disclosure, and are not intended to limit the scope of the invention in any way, wherein: Figure 1 schematically shows, in a three-dimensional perspective view, a pair of monopiles stored according to the prior art. Figure 2A schematically shows, in a three-dimensional perspective view, a monopile stored according to a first embodiment of the method of the present disclosure. Figure 2B schematically shows, in a three-dimensional perspective view, a monopile stored according to a second embodiment of the method of the present disclosure. Figure 3 schematically shows, in a three-dimensional perspective view, a part of a seating arrangement comprising a plurality of seating members according to a first embodiment. Figures 4A and 4B schematically show, in a frontal and top view, a seating member according to a second embodiment. Figure 5 schematically shows, in a three-dimensional perspective view, a seating member that is suspended from a spreader lifting beam. Figure 6 schematically shows, in a three-dimensional perspective view, an embodiment of the pile lifting system that is used for lifting and positioning the tubular structural pile. Figure 7 schematically shows, in a frontal view along the central longitudinal axis of the tubular structural pile, the pile lifting system prior to lifting and / or posterior to lowering the tubular structural pile from, or into, the seating arrangement. Figure 8 schematically shows, , in a three-dimensional perspective view, an embodiment of the pile holding device that is comprised in the pile lifting system of figure 7.

[0037] Figure 1 schematically shows a pair of tubular structural piles, e.g. monopiles 1, stored according to the prior art. The monopiles 1 are stored onto a supporting surface, e.g. ground surface 2, in a yard area. At the respective outer end sections 11, 12 of the monopile, the monopile 1 is supported onto specifically created storage sand dunes 3. These project-specific sand dunes 3 are erected in the yard area, thereby requiring vast amounts of sand (up to, or even over 30.000m 3< ) and secondly require to be formed in small layers that need to be compacted before putting on a next layer in order to be able to be stable enough to support the weight of the monopiles 1, and the limit deformations of the sand dunes, to effectively distribute the weight thereof over a larger surface area of the ground surface 2.

[0038] Figure 2A schematically shows a monopile 1 stored according to a first embodiment of the method of the present disclosure. The monopile is supported by a seating arrangement 10 tot comprises plurality of seating members 101 - 106 that are arranged adjacently for having a certain predefined length l 100 as defined in a direction parallel to the central longitudinal axis I of the monopile 1. In the current example, a single closely spaced cluster of seating members 100 is formed. The monopile 1 is then positioned such that the center of gravity is positioned in between the respective outer ends of the seating arrangement 10, which are here formed by the first and sixth seating member 101, 106 of the closely spaced cluster of seating members 100.

[0039] Figure 2B schematically shows a monopile 1 stored according to a second embodiment of the method of the present disclosure. The seating arrangement 10 of the second embodiment comprises two spaced apart clusters of seating member 100a, 100b, which are arranged at a distance d 100 , which may vary, but is always shorter than the length of the monopile 1. The first cluster 100a, comprising three seating members 101a, 102a, 103a, is closer to the first outer end section 11 (when compared to the second cluster 100b) and the second cluster 100b, comprising four seating members 101b - 104b is, mutatis mutandis, arranged closer to the second outer end section 12. Further clusters may be envisioned, depending for instance on the requirements imposed by the monopile and / or yard area, in between the first and second clusters 100a, 100b. The distance between the respective clusters 100a, 100b and / or the distances from the respective outer end sections 11, 12, may be defined on the basis of, for instance, an allowable bending stress in the monopile 1 and / or a minimum length of a free end of the monopile 1 that is required for the pile positioning systems 2000 in order for the pile positioning systems 2000 to pick up and (re-)position the monopile 1.

[0040] The specific seating arrangement 10 is shown without the monopile 1 thereon in figure 3. The respective seating members 101 - 106 are all substantially the same and formed from a plurality of, in this case six, supporting bodies 31 - 36 that are adjacently arranged along a traverse axis III for forming a row of supporting bodies 30, that together form a respective seating member 106, that are directly positioned onto the ground surface 2. The different seating members 101 - 106 are arranged along the longitudinal axis II, that is substantially perpendicular to the traverse axis III. A predefined arrangement of supporting bodies 31 - 36 is thereby obtained that forms the single closely spaced cluster of seating members 100. The predefined arrangement is in the current embodiment a two-dimensional linear array, that extends as rows of supporting bodies 30 along the traverse direction III and columns of supporting bodies 40 along the longitudinal direction II. It is noted however, that a seating member may be arranged from more than one row of supporting bodies that are arranged in line with each other. Additionally, the seating members 101 - 106 may also be indirectly supported onto the supporting surface, for instance by arranging a footing member in between the seating member and the supporting surface, that allows to increase the height of the seating member.

[0041] The supporting bodies 31 - 36 are formed from a closed-off flexible container that is filled with a filling of a loose granular substance, such as sand. The supporting bodies 31 - 36 of the current embodiment can thereby be described as filled and closed-off sandbags. The flexible containers of the supporting bodies are preferably made from geotextile, which can be selected to have a suitable tensile strength. In the current embodiment the of supporting bodies 31 - 36 of the respective row 30 are interconnected by interconnecting the flexible containers of directly adjacent supporting bodies, such that supporting body 31 is connected to supporting body 32, which is in turn also connected to supporting body 33. This can be achieved, for instance, by sowing the respective abutting sides of the (geotextile) flexible containers of respective supporting bodies together.

[0042] The outer ends of the row of supporting bodies 30, in particular first and sixth supporting body 31, 36 have an (equally) increased height with respect to the centrally arranged supporting bodies 32 - 35; in particular the centrally arranged supporting bodies 32 - 35 have an equal height.

[0043] Figures 4A and 4B schematically show, in a frontal and top view, a seating member according to a second embodiment, that differs from the first embodiment of figure 3 in that the centrally arranged supporting bodies 132 - 135 also have a different height, as is explained below. Again, the outer supporting bodies 131, 136 have the same, highest, height of the supporting bodies 131 - 136. The central supporting bodies 133, 134 are seen to have the same, lowest, height of the supporting bodies 131 - 136. A set of intermediate supporting bodies, 132, 135 are seen to have an intermediate height that is higher than the height of the central supporting bodies 133,134, but lower than the height of the outer supporting bodies 131, 136. The row of supporting bodies 130 is further arranged to be substantially mirror-symmetric along mirror plane IV that is substantially perpendicular to the traverse axis III and parallel to the longitudinal axis II; this also holds for the embodiment of figure 3. Thereby, an upper side (as best seen in figure 4A) of the cross-section of the seating member, as taken perpendicular to the longitudinal axis II, approximates a substantially concave, U-, and / or V-shaped, wherein the approximate of the substantially concave, U-, and / or V-shape is a continuous or non-continuous shape, in particular wherein the non-continuous shape is a piecewise linear and / or stepwise concave, U-, and / or V-shape. The non-continuous shape, i.e. discrete shape, is obtained due to the use of substantially rectangular supporting bodies 31-36, 131-136. The rectangular supporting bodies 31-36, 131-136 preferably have rounded corners and / or edges for preventing stress concentrations in the flexible containers. It is noted that the upper side of the cross-section of row of supporting bodies 30 is shaped, and in at least the current embodiment also sized, to correspond to the outer circumference (i.e. its size and shape) of the monopile 1.

[0044] In the embodiment of figures 4A - 4B, the supporting bodies 31 - 36 of the respective row 30 are interconnected by means of one or more connecting elements, in particular tension members 141, 142. A first tension member 141 can be arranged around the circumferential sides of the supporting members 131 - 136, whereas a second tension member 142 can be connected to the top surface, bottom surface and / or arranged along both the top and bottom surfaces of the supporting members 131 - 136. Additionally, the one or more connecting elements may also be arranged in combination with the sown together sides of the supporting bodies 31 - 36.

[0045] A further alternative embodiment of a seating member is suspended from a spreader lifting beam 1000 that is lifted using a reach-stacker 1001, as is shown in figure 5. The seating member 230, that is formed as a row of interconnected supporting bodies comprising supporting bodies 231 - 236, has a substantially flat upper surface as the height of the supporting bodies 231 - 236 is substantially equal. The flexible containers of the supporting bodies 231 - 236 are interconnected in a substantially similar manner as the flexible containers of supporting bodies 31 - 36. The seating member 230 is provided with a lifting arrangement 240 comprising a plurality of lifting slings and / or lifting cables 241. In the current embodiment, the lifting arrangement 240 is fixedly connected to the seating member 230. Each of the respective supporting bodies 231 - 236 forming the seating member 230 is arranged with its own lifting sling 241 that is arranged to the front- and back sides of the respective supporting bodies 231 - 236, for instance by means of a stitched connection 242. The lifting sling 241 is, preferably, arranged to also run under the bottom of the respective supporting bodies 231 - 236, for an improved support.

[0046] A respective seating member can than be picked up and lifted using a suitable spreader lifting beam 1000. The spreader lifting beam 1000 comprises a central longitudinal beam member 1010 that is fitted, on a first side, with a plurality of, in particularly evenly, spaced apart suspension points 1021 that are arranged for receiving the respective lifting slings 241 therein. The distance between the respective suspension points 1021 is therefore substantially equal to the distance between the respective lifting slings 241. On a second, opposite, side, the central longitudinal beam member 1010 is arranged with a pair of spaced apart hook-on points 1031, for a beneficial loading of the central longitudinal beam member 1010, the hook-on points 1021 are preferably spaced apart and arranged at respective outer end sections 1011, 1012 of the central longitudinal beam member 1010, in particular no further to the outer end as the outer most of said suspension points 1021, and preferably further than the second outer most of said suspension points 1021. Respective spreader lifting beam cables and / or slings 1040 may than be used to suspend the spreader lifting beam 1000 from a suitable lifting device, such as a reach-stacker 1001.

[0047] Figures 6 - 8 show various aspects of lifting and transporting the tubular structural piles, such as the monopiles 1, using a pile positioning device 2000. The pile positioning system 2000 comprises a pile holding device 2100 and a drivable transport system 2200, in particular comprising a pair of spaced apart multi-axle vehicles 2210, 2220, that in the current embodiment each comprise a plurality of coupled Self Propelled Modular Transporters (SPMTs) 2230.

[0048] The pile holding device 2100 comprises a lifting frame 2110 and a lifting cradle 2120. The pile holding device 2100 is removably arranged onto the spaced apart pairs of Self Propelled Modular Transporters (SPMTs) 2230. In order to stably position the lifting frame 2110 onto the SPMTs 2230 and the distribute the gravitational forces of the pile holding device 2100 and a monopile 1 that is being lifted, a base footing 2111 having a large footprint is arranged. The large footprint is obtained as the length l 2111 of the base footing 2111 is at least halve of the height of the lifting frame 2110 and its width w 2111 spans at least the width of a single SPMT that is used for the drivable transport system

[0049] The lifting frame 2110 holds the lifting cradle 2120 for holding the tubular structural pile, e.g. monopile 1, therein (see figure 8). The lifting cradle 2120 is movable in the vertical direction V for lifting and lowering the monopile 1 with respect to the supporting surface 2.

[0050] The lifting frame 2110 is arranged on top of the height-adjustable cargo platform 2231 of the SPMTs 2230, such that the steps of lifting and lowering of the monopile comprise, respectively, increasing and decreasing the height of the height-adjustable cargo platform 2231. Typical SPMTs 2230 comprise such height-adjustable cargo platforms 2231. In the current embodiment, the lifting cradle 2120 is also vertically movably with respect to the lifting frame 2110, in particular the base footing 2111 thereof. The lifting cradle 2120 made be made vertically movably with respect to the lifting frame 2110 by means of a plurality of vertically arranged hydraulic lifting cylinders 2213 that are arranged in pairs with each column beam member 2112. These hydraulic lifting cylinders 2213 enable the vertical movement of the cradle coupling points 2114 whereto the lifting cradle 2120 is (removably) connected to.

[0051] The lifting cradle 2120 is formed by a flexible U-shaped member, in particular made from a, or a pair of, lifting slings 2121 that are arranged for receiving and holding the monopile 1 therein. The lifting frame 2110 is substantially n-shaped having the pair of spaced apart column beam members 2112 that are interconnected by means of a girder beam member 2115. The girder beam member 2115 is a telescopic beam member, such that the distance between the pair of spaced apart column beam members 2112 is adjustable for adjusting the lifting frame 2110 to an outer diameter of the pile 1 that is to be lifted and transported. One of the column beam members 2112 is arranged with a thereto connected lattice structure 2116 for increasing the stability of the lifting frame 2110.

[0052] Figure 7 shows in a frontal view along the central longitudinal axis of the monopile 1a, the pile positioning system 2000 prior to lifting and / or posterior to lowering the monopile 1a from, or into, the seating arrangement 100. The monopile 1a is seen to be stored in a parallel arrangement next to a second monopile 1b that is stored in the same way. By adjusting the lifting frame 2110 to the outer diameter D 1 of the pile 1a in such a way that the interior distance d 2110 between the respective spaced apart column beam members 2112 is slightly larger than the outer diameter D 1 , the overall width of the pile positioning device 2000 is minimized as much as possible. In combination with the column beam members 2112, that are relatively slender, the monopiles 1a and 1b can be stored at a relatively short distance d ab next to each other; the width of the column beam member 2112 that is not arranged with the lattice structure 2116 is therefore smaller than the distance d 1ab . Hereby many piles can be stored on the yard area, as they can be tightly packed. In the process of placing the pile 1a onto the seating arrangement 100, the pile 1a is suspended at both longitudinal outer end sections in a respective lifting cradle 2120 of at least pile position systems 2200 (each arranged at the other outer end section). The pile 1a needs only a minor vertical lifting in order to be able to move it in the longitudinal direction over the seating arrangement 100. Once the pile 1a is positioned, it can be lowered (as described above) such that it is received in the seating members of the seating arrangement 100. The pile position systems 2200 can then move along the longitudinal direction towards, and past, the outer ends of the pile 1a, such that a next pile can be picked up and stored, or vice versa.

[0053] As the pile holding device 2100 is separate from the SPMTs 2230, it can simple be taken off the SPMTs when not needed and stored somewhere on, for instance, the yard area on its base footing 2111, as is shown in figure 8. This allows for a relatively simple solution for lifting and positioning the monopiles 1 from, and toward, the seating arrangement, that is able to employ a drivable transport system 2200 comprising standard SPMTs 2230 that are typically readily available.

[0054] The hereabove presented embodiments of the method of storing, the seating members, the spreader lifting beam and the pile positioning system may all be suitably combined for forming further embodiments. Additionally, the present invention is not limited to the embodiments shown, but also extends to other embodiments falling within the scope of the appended claims.

Claims

1. Method of storing one or more tubular structural piles, such as a pin pile or monopile, in a horizontally lying state at a spaced apart distance from a supporting surface, in particular a ground surface, wherein the method comprises the steps of: - providing, on the supporting surface, a seating arrangement comprising one or more seating members arranged along a longitudinal axis for receiving and holding the tubular structural pile in the horizontally lying state therein at the space apart distance from said supporting surface; - positioning the tubular structural pile in the horizontally lying state in the one or more seating members of the seating arrangement such that a center of gravity of the tubular structural pile is positioned in between longitudinal outer ends of the seating arrangement and such that the central longitudinal axis of the tubular structural pile is substantially parallel to the longitudinal axis; characterized in that the step of providing the one or more seating members of the seating arrangement comprises the steps of: - providing a plurality of supporting bodies, wherein a supporting body is formed from a flexible container comprising a filling of a loose granular substance, such as sand and / or gravel; - positioning the supporting bodies for forming the one or more seating members.

2. Method according to claim 1, wherein the step of arranging the supporting bodies for forming the one or more seating members comprises forming a respective seating member by positioning a plurality of supporting bodies in a predefined pattern of adjacent supporting bodies.

3. Method according to claim 2, wherein the predefined pattern comprises one or more traversely extending rows of adjacently positioned supporting bodies that extend along a traverse axis that is substantially perpendicular to the longitudinal axis, wherein a row comprises two or more, preferably three or more, more preferably four or more, adjacently positioned supporting bodies; and / or wherein the predefined pattern comprises one or more longitudinally extending columns, of adjacently positioned supporting bodies that extend along the longitudinal axis, wherein a column comprises two or more, preferably three or more, more preferably four or more, adjacently positioned supporting bodies.

4. Method according to any of the preceding claims, wherein a respective seating member has a first traverse outer end, as seen along the traverse axis, that is higher than the average height of the seating member, and, preferably, a second, opposite, traverse outer end that is higher than the average height of the seating member; and / or wherein a respective seating member has a central section that is in between the respective outer traverse ends of the seating member, wherein the central section has a lower height compared to the average height of the seating member; and wherein the step of positioning the tubular structural pile comprises positioning the tubular structural pile such that, as seen in a top view along a vertical axis that is substantially perpendicular to the supporting surface, the central longitudinal axis is positioned in between the respective outer traverse ends of the seating member and / or is positioned in the central section of the seating member.

5. Method according to any of the preceding claims, wherein an upper side of the cross-section of the seating member, as taken perpendicular to the longitudinal axis, approximates a substantially concave, U-, and / or V-shape, wherein the approximate of the substantially concave, U-, and / or V-shape is a continuous or non-continuous shape, in particular wherein the non-continuous shape is a piecewise linear and / or stepwise concave, U-, and / or V-shape; and wherein the step of positioning the tubular structural pile comprises positioning the tubular structural pile such that, as seen in a top view along a vertical axis that is substantially perpendicular to the supporting surface, the central longitudinal axis is positioned in substantially central part of the substantially concave, U-, and / or V-shape.

6. Method according to any of the preceding claims, wherein at least a portion of the upper side of the cross-section of the seating member is shaped, and preferably sized, to correspond to the outer circumferential shape, and preferably the size, of the structural tubular pile; and wherein the step of positioning the tubular structural pile comprises positioning the tubular structural pile such that corresponding sections of the respective upper side and the outer circumferential shape abut.

7. Method according to any of the preceding claims, comprising, prior and / or posterior to step of positioning the supporting bodies, a step of adjusting the height of a supporting bodies by adding, removing and / or compacting the filling of loose granular substance inside of the flexible container.

8. Method according to any of the preceding claims, wherein the flexible container is formed from a flexible fabric, in particular a flexible high-tensile strength fabric such as a geotextile or a fiber-reinforce polymer sheet, and wherein the flexible container is closed-off for retaining the filling of the loose granular substance therein.

9. Method according to any of the preceding claims, wherein a set of supporting bodies of the plurality of supporting bodies are interconnected and wherein the step of positioning the supporting bodies comprises simultaneously positioning the first set of supporting bodies; and preferably, wherein the supporting bodies comprise a bottom that is positioned onto the supporting surface during the step of positioning the supporting bodies and a top that is arranged to substantially face the tubular structural pile; and wherein the supporting bodies forming a respective set are interconnected by means a bottom connecting member that interconnects the respective bottoms of the respective set and / or by means a top connecting member that interconnects the respective tops of the respective set, and / or by means of a circumferential connecting members that connect side walls of the flexible containers of the supporting structure of the respective set.

10. Method according to claims 3 and 9, wherein the set of supporting bodies is formed by a number, or all, of the adjacently positioned supporting bodies of a row and / or column of the predefined pattern of the respective seating member.

11. Method according to claim 9 or 10, wherein the set of interconnected supporting bodies are simultaneously positioned by simultaneously lifting the respective set by means of a movable lifting device, wherein a spreader lifting beam is arranged in between the lifting device and the set of interconnected supporting bodies, and wherein the spreader lifting beam comprises one or two hook-on points for connecting it to the lifting device and comprises a plurality of spaced apart suspension points for suspending the set of interconnected supporting bodies from the spreader lifting beam using a plurality of lifting cables and / or slings; and wherein the steps of providing and positioning the plurality of supporting bodies comprises: - connecting the plurality of lifting cables to the set of interconnected supporting bodies; - lifting and moving the interconnected supporting bodies using the movable lifting device to a designated location where a seating member of the seating arrangement is to be arranged; - lowering and positioning the set interconnected supporting bodies onto the supporting surface according to the predefined pattern; - disconnecting the plurality of lifting cables from the set of interconnected supporting bodies.

12. Method according to any of the preceding claims, wherein the step of positioning the tubular structural pile comprises, by using a pile positioning system: - lifting and moving the tubular structural pile in the horizontally lying state from a first position to the seating arrangement; - lowering the tubular structural pile in the horizontally lying state into the one or more seating members of the seating arrangement; preferably, wherein the pile positioning system comprises a pile holding device and a drivable transport system, in particular comprising a pair of multi-axle vehicles, wherein the pile holding device comprises a lifting frame and a lifting cradle, wherein the pile holding device is arranged onto the drivable transport system, such as Self Propelled Modular Transporters (SPMTs), that are arranged to move over the supporting surface; wherein said lifting frame holds the lifting cradle for holding the tubular structural pile therein, wherein the lifting cradle is movable in the vertical direction for lifting and lowering the tubular structural pile with respect to the supporting surface; and / or preferably, wherein in the step of positioning the tubular structural pile two pile positioning systems are used, wherein a first pile positioning device is arranged to lift the structural pile at a first lifting location that is in between the center of gravity and a first longitudinal outer end of the tubular structural pile; and wherein a second pile positioning device is arranged to lift the structural pile at a second lifting location that is in between the center of gravity and a second longitudinal outer end, that is opposite to the first longitudinal outer end, of the tubular structural pile.

13. Method according to any of the preceding claims, comprising storing a second tubular structural pile, such as a pin pile or monopile, in a horizontally lying state above a supporting surface, wherein the second tubular structural pile is positioned in a second seating arrangement, preferably substantially similar to the seating arrangement, to be stored substantially parallel to the tubular structural pile.

14. Seating member for use in the method according to any of the preceding claims, wherein the seating member comprises a plurality of supporting bodies that comprises a flexible container comprising a filling of a loose granular substance, such as sand and / or gravel; wherein the plurality of supporting bodies are arranged in a predefined pattern of adjacent supporting bodies; and wherein a set of a part of, or all of, the supporting bodies of the plurality of supporting bodies that form the seating member are interconnected.

15. Seating member according to claim 14, wherein the flexible container is formed from a flexible fabric, in particular a flexible high-tensile strength fabric such as a geotextile or a fiber-reinforce polymer sheet, and wherein the flexible container is closed-off for retaining the filling of the loose granular substance therein; and / or wherein the supporting bodies comprise a bottom that is arranged to face the supporting surface and a top that is arranged to face the tubular structural pile; and wherein the supporting bodies forming the set are interconnected by means a bottom connecting member that interconnects the respective bottoms of the respective set and / or by means a top connecting member that interconnects the respective tops of the respective set, and / or by means of a circumferential connecting members that connect side walls of the flexible containers of the supporting structure of the respective set.

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