Pile installation

Abstract

A pile driving method for vertically driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a single pile of an offshore wind turbine, into the soil, such as into the seabed, using a pile driving system, the pile driving system includes at least one hammer device and a torsional vibration driver.

Description

Technical Field

[0001] The invention relates to the field of vertically installing a hollow tubular pile with a vertical centerline, a top end and an open foot end into soil, for example into the seabed. For example, the pile is a relatively large diameter pile with an outer diameter of at least 5 meters at the open foot end. For example, the pile is a so-called monolithic pile of an offshore wind turbine. Background Art

[0002] Practical embodiments of monolithic piles currently envisioned include monolithic piles having a diameter between 5 and 12 meters and a length between 60 and 120 meters. In embodiments, the wall thickness of the pile is greater than 10 centimeters. For example, the pile may have a mass greater than 1000 tons, such as greater than 2000 tons, or even greater than 3000 tons.

[0003] In a practical embodiment, the pile is a steel pile, for example consisting of ring segments welded end to end, each ring segment consisting of arc segments welded to each other to form a ring.

[0004] The pile may comprise, for example, a tapered or conical section between a lower pile section of larger diameter and a pile top section of smaller diameter. In another embodiment, the pile has a uniform cross section over its length. Preferably, the pile has a circular horizontal cross section over its entire length. In an embodiment, the top end of the pile is provided with a connection structure for a wind turbine tower, possibly with an interface for a transition piece, such as a flange for bolting and / or a sliding joint connection structure.

[0005] The pile may also be part of a set of piles forming part of a foundation of an offshore wind turbine, for example the foundation being embodied as a tripod secured to three piles which have been driven into the sea bed. Summary of the invention

[0006] A first aspect of the invention relates to a piling system for vertically driving a hollow tubular pile having a vertical centerline, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile for an offshore wind turbine) into soil (e.g. into the seabed), wherein the piling system comprises a hammer device and a torsional vibration drive.

[0007] The monolithic pile installation process is a process of driving a monolithic pile vertically into the seabed. The pile driving force, i.e., the force driving the pile into the seabed in the axial direction, can be generated by a combination of a vibrating device, an impact hammer, a pile gyrator, and one or more spiral ribs and / or excavating blades mounted on the monolithic pile.

[0008] Typically, piles are driven into the seabed using an impact hammer, such as a drop-weight pile driver device or a hydraulic impact hammer. However, this type of pile driving process generates a lot of noise, which has a negative impact on the environment, especially on wildlife in the environment. Therefore, during the pile driving process, expensive and elaborate noise mitigation devices, such as bubble sheets, are deployed.

[0009] An alternative to the percussion hammer is to use a vibrating pile driver device to drive the pile into the seafloor. This technique produces less noise than using a percussion hammer.

[0010] It is known from WO2020 / 207903 to drive a monolithic pile into the soil using a vibration force directed along the longitudinal axis of the monolithic pile. In addition to the vibration driving force, water can be used to remove soil from under the foundation pile. This prior art installation process requires a complex device to be provided at the foot end of the monolithic pile. At the end of the installation process, the device must be excavated to enable it to be used for the installation of another foundation pile. The excavation of this complex device is difficult and time-consuming.

[0011] For the use of both known impact hammers and vibratory devices, their effectiveness for larger diameter piles is expected to be limited. It is expected that these types of piling devices will not be able to generate the pile driving forces required to effectively drive the larger diameter foundation piles envisioned in the near future into the seabed.

[0012] An object of the first aspect of the present invention is to overcome one or more limitations of prior art piling systems and methods and to at least provide an alternative thereto. The first aspect of the present invention also aims to provide an improved, more particular and more efficient monolithic pile installation process.

[0013] According to a first aspect of the invention, a piling system as defined in claim 1 is proposed.

[0014] The system is based on the presence of one or more pile driver devices (e.g. drop-weight pile driver devices) engaged on the top end of the pile, e.g. to provide all or most of the vertical piling energy, and on the presence of a torsion drive comprising one or more vibrating pile driver devices. The one or more vibrating pile driver devices may in fact be used mainly to reduce the surface friction between the pile and the soil, e.g. without generating vertical piling energy, or only generating less vertical piling energy than the one or more drop-weight pile driver devices.

[0015] The first aspect of the present invention also provides a method according to claim 20.

[0016] In the method of the invention, a combination of systems is used, the method being based on the presence of a hammer device, for example comprising one or more drop-weight pile driver devices, which is engaged on the top end of the pile, for example to provide all or most of the vertical piling energy, and the method being based on the presence of a torsional vibration drive, for example comprising one or more vibrating pile driver devices. The torsional vibration drive can in fact be used mainly to reduce the surface friction between the pile and the soil, for example, without generating vertical piling energy, or only generating less vertical piling energy than the hammer device.

[0017] In an embodiment of the piling system according to the first aspect of the invention, the piling system is for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, the piling system comprising:

[0018] - at least one hammer device configured to transfer energy from the respective hammer device to the top of the pile at a respective frequency along a piling axis, wherein the piling axis is parallel to, and preferably coincides with, a central longitudinal axis of the pile; and

[0019] - a torsional vibration drive, wherein the torsional vibration drive comprises at least one vibrating pile driver device engaged on a pile column or on a hammer device, and wherein each vibrating pile driver device of the torsional vibration drive is constructed and operated to apply an alternating force at a corresponding vibration frequency about a pile driving axis simultaneously with the operation of at least one hammer device.

[0020] Here, the hammer device is understood to be an impact hammer or a vibrating hammer.

[0021] For example, the hammer, also called drop weight, may be embodied as a (hydraulic accelerated) drop weight hammer device, as is commonly used for (offshore) piling.

[0022] For example, the vibratory hammer can be embodied as a vibratory pile driver device, as is commonly used for (offshore) piling of piles, and is configured to apply an alternating vertical force with a corresponding vibration frequency along a vertical working line associated with the pile driver device and parallel to the piling axis, preferably coinciding with the piling axis.

[0023] In an embodiment, the system further comprises a floating support connecting the torsional vibration drive to the hammer device, or connecting the torsional vibration drive to the pile, wherein the floating support is configured to allow free movement of the torsional vibration drive along the piling axis to prevent energy from being directly transferred from the hammer device to the torsional vibration drive, and to restrict, preferably prevent, free movement of the torsional vibration drive about the piling axis to enable torsional forces to be directly transferred from the torsional vibration drive to the hammer device or the pile.

[0024] The purpose of the pile driving system of the present invention is to reduce the surface friction between the pile and the soil by using a vibration drive so as to facilitate driving the pile into the seabed by using a hammer device. Since the impact force generated by the impact hammer during the pile driving process may damage the vibration device without a floating support, the floating support enables the vibration drive device to be combined with the impact hammer.

[0025] In this embodiment of the piling system according to the first aspect of the invention, the hammer device is combined with a vibration device via a floating support for vibrating the pile column about its centre line during piling.

[0026] The torsional vibration drive generates an alternating torsional force to produce torsional vibrations of the pile, ie the torsional force causes the pile to rotate back and forth about its central axis.

[0027] In this case, vibration is a motion in which an object, i.e., a pile, moves in one direction and then moves approximately the same distance in the opposite direction.

[0028] Due to the torsional vibration of the pile, the pile surface of the pile moves relative to the soil of the seabed, which reduces the friction between the pile and the soil. Therefore, vibrating the pile about its longitudinal axis reduces the friction between the pile and the soil. Due to the reduced friction, less force is required to drive the pile into the seabed. In addition, the pile driving process can be shortened. This enables an efficient pile driving concept.

[0029] Furthermore, these aspects achieve a reduction in the noise generated by the piling process and thus in the environmental impact. The invention may therefore also achieve a reduction in the noise mitigation measures required to keep the environmental impact of the piling process within acceptable limits, which may further reduce the cost of the piling process.

[0030] The floating support limits the maximum acceleration, and preferably the maximum deceleration, of the vibratory drive in the vertical direction during the piling process.

[0031] During the pile driving process, the impact of the hammer accelerates the pile. The hammer is coupled to the pile so that the hammer's pile driving force can be transferred directly from the hammer to the pile, i.e., with minimal energy losses. At each impact of the hammer, the pile is accelerated in the vertical direction and is thereby driven into the seabed.

[0032] Due to the floating support, the impact force generated by the hammer is not directly transmitted to the vibration drive. In addition, due to the floating support, the maximum acceleration of the pile in the vertical direction during the pile driving process is therefore significantly greater than the maximum acceleration of the vibration drive. As a result, the impact of the hammer on the vibration drive is reduced, which enables the use of the vibration drive in combination with the impact hammer.

[0033] In an embodiment, the piling system comprises a plurality of hammer devices arranged to apply vertical forces along working lines associated with respective hammer devices, and wherein the vertical forces combine to produce a resultant vertical force having a resultant vertical force working line, and wherein the vertical force working line is parallel to the piling axis, preferably coincident with the piling axis.

[0034] In an embodiment, at least one of the hammer devices is a vibratory hammer device preferably engaged on the top end of the pile column, the vibratory hammer device being configured to transfer energy from the respective vibratory hammer device to the top of the pile column at a respective frequency along the piling axis.

[0035] In an embodiment, at least one hammer device is a drop-weight pile driver device engaged on a top end of the pile column, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile column at a respective frequency along the pile driving axis.

[0036] In an embodiment, the torsional vibration drive comprises a plurality of vibrating pile driver devices arranged, for example, in a circular array around a piling axis, and wherein each vibrating pile driver device is configured to apply an alternating force at a vibration frequency in a plane perpendicular to the piling axis to vibrate the pile column around the piling axis.

[0037] In an embodiment, the torsional vibration driver is distinct from the hammer device and is configured to engage the pile, for example, at a larger diameter lower pile section below a smaller diameter pile top section of the pile.

[0038] In an embodiment, the floating support enables the torsional vibration driver to move along a vertical working line relative to a hammer device, such as an impact hammer device, within a range of at least 20 cm, preferably within a range of at least 40 cm, such as a range of 60 cm or more.

[0039] In an embodiment, the floating support is configured to cushion the impact force generated by at least one hammer device when the impact force is transmitted from the hammer device to the torsional vibration driver, for example, the floating support is provided with one or more elastic bodies, such as one or more springs or cylinders, between the impact hammer or pile and the torsional vibration driver.

[0040] In an embodiment, the torsional vibration driver is configured to apply a torsional vibration load having a frequency of at least 50 Hz, preferably at least 65 Hz, for example 80 Hz.

[0041] In an embodiment, at least one hammer device is a vibratory hammer device and is configured to apply a vibratory load along the piling axis having a frequency of at least 14 Hz, preferably at least 17 Hz, for example 20 Hz.

[0042] In an embodiment, the hammer device is configured to generate impact forces at a piling frequency, and wherein the torsional vibration drive generates torsional forces at a torsional frequency, and wherein the torsional frequency is at least three times, preferably at least four times, such as at least five times, the piling frequency.

[0043] In an embodiment, the floating support is provided with damping means which reduce a movement of the torsional vibration driver along the piling axis and relative to the hammer device, wherein the movement is caused by the hammer device.

[0044] In an embodiment, the damping device has an operating path of several decimeters, ie a path in which the relative speed of the torsional vibration drive is reduced, for example an operating path of at least 20 cm, preferably more than 30 cm, for example at least 40 cm.

[0045] In an embodiment, the buffer device comprises one or more hydraulic cylinders coupled to a gas buffer, and wherein the hydraulic cylinders preferably have a working trajectory of 30 cm.

[0046] In an embodiment, the piling system comprises an anvil configured to couple with a top end of the foundation pile column to transmit an axial piling force from the pile driver to the foundation pile column, and preferably wherein the floating support is mounted to the anvil.

[0047] In an embodiment, the floating support comprises a plurality of support arms, each support arm having a base end and a support end for connecting the annular frame of the torsional vibration driver to the pile. The support arm is pivotally mounted at its base end to the top end of the pile and pivotally mounted at its support end to the frame of the torsional vibration driver.

[0048] In another embodiment, the support arms extend substantially tangentially to a circle centered on the pile driving axis, e.g. similar to the floating support of the sixth aspect of the invention. The floating support preferably comprises a plurality of elastic bodies, e.g. implemented as hydraulic cylinders connected to gas buffers. The elastic bodies are e.g. mounted between the pile and the annular frame of the floating support to dampen the vertical movement of the torsional vibration driver relative to the hammer device.

[0049] In an embodiment, the piling system comprises a sleeve for receiving a top end of the pile, wherein the sleeve is configured to be fixed to the pile to resist rotation about a longitudinal axis of the pile, and preferably wherein the floating support is mounted to the sleeve.

[0050] In an embodiment, the floating support is mounted to the top end of a monolithic pile, the monolithic pile comprising, for example, a ring mounted on the top end of the pile.

[0051] A first aspect of the invention also provides a vessel, such as a jack-up vessel, provided with a piling system according to one or more of the preceding claims.

[0052] The first aspect of the invention also provides a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, preferably a piling system according to one or more of the preceding claims, wherein the piling method comprises the following steps:

[0053] - setting up the pile with the open foot in the seabed while supporting the pile above the horizontal plane in a radial direction using pile guides mounted on a vessel, such as a jack-up vessel;

[0054] - using at least one hammer device to generate an axial piling force along a piling axis to drive the pile into the seabed, wherein the piling axis is aligned with a vertical centerline of the pile;

[0055] - using a torsional vibration drive to generate a torsional force about the pile driving axis to rotate the pile about a vertical centerline, thereby reducing friction between the pile and the seabed; and

[0056] - allowing the torsional vibration drive to move freely along the piling axis to prevent the impact force from being directly transmitted from the impact hammer to the torsional vibration drive, and restricting, preferably preventing, the torsional vibration drive from moving freely around the piling axis to enable the torsional force to be directly transmitted from the torsional vibration drive to the impact hammer or the pile.

[0057] In an embodiment, one or more vibratory pile driver devices of the torsion drive have a horizontal working line oriented tangentially to the outer surface of the tubular pile column to generate torsional vibrations, and the hammer device includes another pile driver device mounted on the top of the pile column and providing a vertical pile driving force.

[0058] In an embodiment, in a method according to the first aspect of the invention, the method is for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0059] - a drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile at a respective frequency along a vertical working line,

[0060] Characterized in that at least one vibrating pile driver device, distinct from the drop-weight pile driver device, is engaged on the top end of the pile column, each vibrating pile driver device being constructed and operated simultaneously with the operation of the at least one drop-weight pile driver device so as to apply an alternating force at a corresponding vibration frequency about a working line associated with the pile driver device.

[0061] Thus, in the method of the invention, a combination of systems is used, one system being based on the presence of one or more drop-weight pile driver devices engaged on the top end of the pile, for example to provide all or most of the vertical piling energy, and another system being based on the presence of one or more vibrating pile driver devices distinct from the one or more drop-weight pile driver devices. The one or more vibrating pile driver devices may in fact be used primarily to reduce the surface friction between the pile and the soil, for example without generating vertical piling energy, or only generating less vertical piling energy than the one or more drop-weight pile driver devices.

[0062] A second aspect of the invention relates to a piling method for driving a hollow tubular pile having a vertical centre line, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile for an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising a plurality of vibratory pile driver devices.

[0063] For example, in the field of driving larger diameter piles, the system disclosed in WO2015 / 190919 is used. FIG. 4 thereof shows a system known in the art as Super Quad Kong. The system has been used to drive a single pile into the seabed for use in a wind farm in the North Sea. The system has four vibrating pile driver devices, which are mounted on a common rigid base, which is clamped on the top of the single pile using a plurality of clamps. Each of these pile driver devices is configured to apply an alternating vertical force at a corresponding vibration frequency along a vertical working line associated with the pile driver device. These alternating vertical forces are combined to produce a composite vertical force having a composite vertical force working line. The working line coincides with the vertical center line of the single pile.

[0064] Another known vibratory pile driving system is the so-called Octa Kong system, in which eight vibratory pile driver devices are mounted on a common rigid ring structure that is clamped to the top of a very large diameter pile using a plurality of clamps. Each of these pile driver devices is configured to apply an alternating vertical force at a corresponding vibration frequency along a vertical working line associated with the pile driver device. These alternating vertical forces combine to produce a resultant vertical force having a resultant vertical force working line. The working line coincides with the vertical centerline of the pile.

[0065] According to a second aspect of the invention, a method as defined in clause 1 is proposed.

[0066] In the method of the present invention, a plurality of vibratory pile driver devices are arranged in a circular array and independently engaged on the top end of the pile column, each vibratory pile driver device being configured to apply an alternating vertical force at a corresponding vibration frequency along a working line associated with the pile driver device, the alternating vertical forces combining to produce a resultant vertical force having a resultant vertical force working line.

[0067] In the method of the present invention, a plurality of vibratory pile driver devices are operated to apply their alternating out-of-phase vertical forces such that the resultant vertical force deviates from and travels about the vertical centerline of the tubular pile column.

[0068] The method of the present invention is intended to reduce the surface friction between the pile and the soil. For example, at least four vibrating pile driver devices are included in a circular array, such as six, or eight, or other numbers. In an embodiment, the pile driver devices are each directly connected, such as clamped to the pile, such as connected to the top of the pile. In another embodiment, the pile driver devices are integrated in a common carrier, such as to enable all devices to be lifted to the top of the pile by a crane.

[0069] In the method of the present invention, these pile driver devices that produce a resultant vertical force that deviates from the vertical centerline of the tubular pile and travels about the vertical centerline can be all the devices used to drive the pile into the soil. In another embodiment, one or more additional pile driver devices are used simultaneously. For example, a single (high-power) drop-weight pile driver device is also used. In another example, one or more additional vibrating pile driver devices are used, which do have a resultant force that coincides with the centerline of the pile.

[0070] In a practical embodiment, the pile driving system includes a controller that monitors the phase of each of a plurality of vibrating pile driver devices that are operated to apply their out-of-phase alternating vertical forces, and that also enables regulation of the out-of-phase operation. As is known in the art, the controller may also enable, for example, regulation of the vibration frequency.

[0071] In a practical embodiment, the movement of the top end of the pile in the horizontal plane is monitored, for example to monitor and / or control the operation of a pile driver device that generates a resultant vertical force that deviates from and travels about the vertical centerline of the tubular pile. For example, such monitoring is accomplished using (laser) distance measuring equipment and / or inertial based measuring equipment or the like.

[0072] A second aspect of the invention also relates to a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0073] - A plurality of drop-weight pile driver devices arranged in a circular array and independently engaged on the top end of the pile, each pile driver device being configured to transfer energy from a respective drop-weight to the top end of the pile at a respective frequency along an operating line associated with the pile driver device, the energy transfers of the pile driver devices in combination producing a resultant vertical force having a resultant vertical force operating line.

[0074] An example of such a method is disclosed in EP 1 781 861. Therein, it is disclosed that for optimum pile driving, a plurality of falling weight pile driver devices are synchronized so that their strikes are within 10 milliseconds.

[0075] According to a second aspect of the invention, a method is provided in which a plurality of drop weight pile driver devices are operated to perform their respective out-of-phase energy transfers such that the resultant vertical force deviates from and travels about a vertical centre line of a tubular pile.

[0076] It will be appreciated that such operation is envisaged to result in reduced surface friction.

[0077] A second aspect of the invention also relates to a piling system as discussed herein.

[0078] A third aspect of the invention relates to a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0079] - a vibrating pile driver device engaged on said top end of said pile column, the vibrating pile driver device being configured to apply an alternating force at a corresponding vibration frequency along a working line associated with the pile driver device.

[0080] For example, see WO2021 / 040523. It is explained here that in order to reduce surface friction, torsional vibrations are introduced into the pile column by the operation of one or more vibrating pile driver devices. In an embodiment, one or more vibrating pile driver devices have a horizontal working line that is oriented tangentially to the outer surface of the tubular pile column so as to generate torsional vibrations. Another pile driver device is installed on the top of the pile column and provides a vertical pile driving force.

[0081] According to a third aspect of the invention, there is provided a piling method for driving a hollow tubular pile having a vertical centre line, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into a seabed, wherein a piling system is used, the piling system comprising:

[0082] a vibrating pile driver device engaged on the top end of the pile, the vibrating pile driver device being configured to apply an alternating force at a corresponding vibration frequency along a working line associated with the pile driver device,

[0083] Characteristically, the vibratory pile driver device is constructed and operated with a horizontal working line so that a lateral vibratory force is applied on the top end of the pile column.

[0084] Thus, instead of torsional vibration, the top end of the pile is effectively caused to oscillate in a vertical plane in order to reduce surface friction.

[0085] A third aspect of the invention is based on the recognition that, particularly for larger diameter piles, effectively inducing torsional vibrations may prove impractical. Controllably oscillating a pile in a vertical plane may be feasible even for larger diameter piles, for example by using a circular arrangement of such pile driver devices operating in unison to produce controlled lateral vibrations of the top end of the pile.

[0086] For example, two vibrating pile driver devices are mounted at diametrically opposed locations on the top end of the pile, and a pair of vibrating pile driver devices are constructed and operated with a horizontal working line, such as a common working line, so that a lateral vibration force is applied to the top end of the pile. One or more additional vibrating pile driver devices may be mounted at other locations on the top end of the pile and have parallel working lines to assist in inducing lateral vibration.

[0087] A third aspect of the invention also relates to a piling system as discussed herein.

[0088] A fourth aspect of the invention relates to a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0089] - A drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile at a respective frequency along a vertical working line.

[0090] For example, the system disclosed in WO2020153838 is used. In this document, a system is described that allows the generation of huge pile driving energies to drive a monolithic pile into the soil. Typically, a very large mass that falls (not accelerated except by gravity) is used here. For example, the energy transfer lacks mechanical impact energy transfer.

[0091] A fourth aspect of the invention provides a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0092] - a drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile at a respective frequency along a vertical working line,

[0093] Characterized in that at least one vibrating pile driver device, different from the drop-weight pile driver device, is engaged on the top end of the pile column, each vibrating pile driver device being constructed and operated to simultaneously with the operation of the at least one drop-weight pile driver device to apply an alternating force at a corresponding vibration frequency along a working line associated with the pile driver device.

[0094] Thus, in the method of the invention, a combination of systems is used, one system being based on the presence of one or more drop-weight pile driver devices engaged on the top end of the pile, for example to provide all or most of the vertical piling energy, and another system being based on the presence of one or more vibrating pile driver devices distinct from the one or more drop-weight pile driver devices. The one or more vibrating pile driver devices may in fact be used primarily to reduce the surface friction between the pile and the soil, for example without generating vertical piling energy, or only generating less vertical piling energy than the one or more drop-weight pile driver devices.

[0095] In this fourth aspect of the invention, one or more vibrating pile driver devices may provide the above-mentioned lateral vibration of the third aspect of the invention. In another embodiment, these one or more vibrating pile driver devices may provide torsional vibration. In another embodiment, one or more vibrating pile driver devices may provide vertical vibration. One or more vibrating pile driver devices may also provide a combination of vibrations as mentioned herein, such as vertical vibration and torsional vibration, such as vertical vibration to reduce surface friction. For example, one or more vibrating pile driver devices provide vibrations at a higher frequency than the operation of a drop-weight pile driver device engaged on the top of the pile.

[0096] A fourth aspect of the invention also relates to a piling system as discussed herein.

[0097] A fifth aspect of the invention relates to a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0098] - a drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile at a respective frequency along a vertical working line,

[0099] - An energy transfer assembly configured to transfer energy from the falling weight to the top end of the pile.

[0100] Such a system is disclosed, for example, in WO2020153838. In this document, a system is described that allows the generation of enormous pile driving energies for driving a monolithic pile into the soil. Typically, a very large mass that falls (not accelerated except by gravity) is used here. For example, the energy transfer lacks mechanical impact energy transfer.

[0101] A fifth aspect of the invention provides a piling method for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as into the seabed, wherein a piling system is used, the piling system comprising:

[0102] - a drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile at a respective frequency along a vertical working line,

[0103] - an energy transfer assembly configured to transfer energy from the falling weight to the top end of the pile,

[0104] Characteristically, the energy transfer assembly is constructed and operative to convert a portion of the energy from the falling weight into a torsional stress wave applied to the top end of the pile.

[0105] A fifth aspect of the invention is based on the recognition that torsional stress waves (which can also be considered as acoustic waves) can be generated by axial, vertically travelling waves, such as can be observed when the energy from a falling weight travels to the top of a pile. In practice, part of the energy is then converted into torsional stress waves, and the remainder continues as axial, vertical waves.

[0106] In an embodiment, for example, the energy transfer assembly includes a tubular section through which energy from a falling weight is transferred to the top of the pile, the tubular section having a spiral wall thickness increase that causes the generation of a torsional stress wave. The section is connected to the top of the pile so that both the torsional stress wave and the axial, vertical stress wave are transmitted to the top of the pile.

[0107] A fifth aspect of the invention also relates to a piling system as discussed herein.

[0108] A sixth aspect of the invention relates to a piling method for vertically driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile for an offshore wind turbine, into soil, such as into the seabed, wherein a piling system is used, which comprises an impact hammer and a vibration drive.

[0109] The monolithic pile installation process is a process of driving a monolithic pile vertically into the seabed. The pile driving force, i.e., the force driving the pile into the seabed in the axial direction, can be generated by a combination of a vibrating device, an impact hammer, a pile gyrator, and one or more spiral ribs and / or excavating blades mounted on the monolithic pile.

[0110] Typically, piles are driven into the seabed using an impact hammer, such as a drop-weight pile driver device or a hydraulic impact hammer. However, this type of pile driving process generates a lot of noise, which has a negative impact on the environment, especially on wildlife in the environment. Therefore, during the pile driving process, expensive and elaborate noise mitigation devices, such as bubble sheets, are deployed.

[0111] An alternative to the percussion hammer is to use a vibrating pile driver device to drive the pile into the seafloor. This technique produces less noise than using a percussion hammer.

[0112] It is known from WO2020 / 207903 to drive a monolithic pile into the soil using a vibration force directed along the longitudinal axis of the monolithic pile. In addition to the vibration driving force, water can be used to remove soil from under the foundation pile. This prior art installation process requires a complex device to be provided at the foot end of the monolithic pile. At the end of the installation process, the device must be excavated to enable it to be used for the installation of another foundation pile. The excavation of this complex device is difficult and time-consuming.

[0113] With the use of known impact hammers and vibratory devices, their effectiveness on larger diameter piles is expected to be limited. It is expected that these types of piling devices will not be able to generate the pile driving forces required to effectively drive the larger diameter foundation piles envisioned in the near future into the seabed.

[0114] The sixth aspect of the invention aims to overcome one or more limitations of prior art piling systems and methods and at least provide an alternative thereto. The sixth aspect of the invention also aims to provide an improved, more particularly more efficient, method of installing a monolithic pile.

[0115] According to a sixth aspect of the invention, a piling system as defined in the clause is proposed.

[0116] The piling system according to the sixth aspect is configured to drive a hollow tubular pile, such as a larger diameter pile having an outer diameter of at least 5 meters at an open foot end, such as a monolithic pile of an offshore wind turbine, vertically into soil, such as a seabed, the pile having a vertical centerline, a top end and an open foot end.

[0117] In an embodiment, according to the sixth aspect of the present invention, the piling system comprises:

[0118] - an impact hammer for generating an axial pile driving force along a pile driving axis, wherein the pile driving axis is aligned with the vertical centerline of the pile, to drive the pile into the seabed;

[0119] a vibration drive for generating an alternating force about the pile driving axis at a vibration frequency to vibrate the pile about a vertical centerline and reduce friction between the pile and the seabed; and

[0120] a floating support which connects the vibration drive to the impact hammer or is configured to connect the vibration drive to the pile,

[0121] The floating support is configured to allow the vibration drive to move freely along the piling axis to prevent the impact force from being directly transmitted from the impact hammer to the vibration drive, and to limit, preferably prevent, the vibration drive from moving freely around the piling axis to enable the torsional force to be directly transmitted from the torsional drive to the impact hammer or the pile.

[0122] The purpose of the pile driving system of the present invention is to reduce the surface friction between the pile and the soil by means of a vibration drive so as to facilitate driving the pile into the seabed by means of an impact hammer. Since the impact force generated by the impact hammer during the pile driving process will destroy the vibration device without a floating support, the floating support enables the vibration drive device to be combined with the impact hammer.

[0123] According to the piling system of the sixth aspect of the present invention, the impact hammer is combined with the vibration device via the floating support to vibrate the pile column about its center line during the piling process.

[0124] The vibration drive generates an alternating torsional force to produce torsional vibrations of the pile, ie the torsional force causes the pile to rotate back and forth about its central axis.

[0125] In this case, vibration is a motion in which an object, i.e., a pile, moves in one direction and then moves approximately the same distance in the opposite direction.

[0126] Due to the torsional vibration of the pile, the pile surface of the pile moves relative to the soil of the seabed, which reduces the friction between the pile and the soil. Therefore, vibrating the pile about its longitudinal axis reduces the friction between the pile and the soil. Due to the reduced friction, less force is required to drive the pile into the seabed. In addition, the pile driving process can be shortened. This achieves an efficient pile driving concept.

[0127] Furthermore, these aspects achieve a reduction in the noise generated by the piling process and thus in the environmental impact. The invention may therefore also achieve a reduction in the noise mitigation measures required to keep the environmental impact of the piling process within acceptable limits, which may further reduce the cost of the piling process.

[0128] With the piling system according to the sixth aspect of the invention, during the piling process the floating support limits the maximum acceleration of the vibration drive in the vertical direction, and preferably limits the maximum deceleration.

[0129] During the pile driving process, the impact of the hammer accelerates the pile. The hammer is coupled to the pile so that the hammer's driving force can be transferred directly from the hammer to the pile, i.e., with minimal energy loss. With each hammer impact, the pile is accelerated in the vertical direction and thus driven into the seabed.

[0130] Due to the floating support, the impact force generated by the hammer is not directly transmitted to the vibration drive. In addition, due to the floating support, the maximum acceleration of the pile in the vertical direction during the pile driving process is therefore significantly greater than the maximum acceleration of the vibration drive. As a result, the impact of the hammer on the vibration drive is reduced, which enables the use of the vibration drive in combination with the impact hammer.

[0131] The floating drive is considered to allow a range of motion of the vibration drive relative to the hammer, wherein the range of motion is preferably at least a few decimeters, ie at least 20 cm, preferably at least 40 cm, for example 60 cm.

[0132] In an embodiment, the floating support is configured to buffer the impact force when it is transmitted from the impact hammer to the vibration driver, for example, the floating support is provided with one or more elastic bodies, such as one or more springs or cylinders, between the impact hammer and the vibration driver.

[0133] In order to further limit the accelerations to which the vibration drive is subjected, the floating support is preferably constructed not only to prevent the hammer force from being directly transmitted to the vibration drive, i.e. to limit the increase in the vertical velocity caused by the impact force of the impact hammer, but also to prevent a significant reduction in the vertical velocity caused, for example, by the vibration drive falling on the floating support, i.e. to reach the outer limit of the relative movement range permitted by the floating support.

[0134] In an embodiment, the floating support is provided with damping means which reduce the relative movement of the vibration drive when one or both limits of the relative movement allowed by the floating support are reached.

[0135] Furthermore, it is proposed that the damping device preferably has an operating path, ie a path of a few decimeters in which the relative speed of the vibration drive is reduced, for example an operating path of at least 20 cm, preferably more than 30 cm, for example at least 40 cm.

[0136] In an embodiment, the buffer device comprises one or more hydraulic cylinders coupled to a gas buffer, and preferably, the hydraulic cylinders have a working trajectory of 30 cm.

[0137] In an embodiment, the floating support enables the vibration driver to move relative to the impact hammer along the piling axis over a range of at least 20 cm, preferably at least 40 cm, such as 60 cm or more.

[0138] In an embodiment, the torsional drive comprises a plurality of vibratory pile driver devices arranged in a circular array about the pile driving axis, wherein each vibratory pile driver device is configured to apply an alternating force at a vibration frequency in a plane perpendicular to a vertical centerline of the pile column to vibrate the pile column about the vertical centerline.

[0139] In an embodiment, a plurality of vibrating pile driver devices are arranged in a circular array. For example, the circular array includes at least three vibrating pile driver devices, such as six, or eight, or other numbers. In another embodiment, a plurality of vibrating devices are supported independently of each other by floating supports, for example, each vibrating pile driver device is supported by a support arm, which is pivotally connected to the impact hammer or to a frame mounted to the impact hammer. In such an embodiment, each vibrating pile driver device can move independently of each other in the vertical direction.

[0140] In an alternative embodiment, the pile driver device is integrated in a common vehicle, wherein the common vehicle is supported relative to the hammer by means of floating supports.

[0141] In another embodiment, the floating support comprises an annular frame which is configured to extend around the piling axis in an operating state and wherein a vibratory drive, such as a plurality of vibratory drives, is mounted to the annular frame.

[0142] In an embodiment, the impact hammer generates impact force at a pile driving frequency and the vibration drive generates torsional force at a torsional frequency, wherein the torsional frequency is at least five times, preferably at least ten times, such as at least twenty times, the pile driving frequency.

[0143] In an embodiment, the floating support comprises a plurality of support arms, each arm having a base end and a support end, wherein the support arm is provided with a pivot axis at its base end and supports the vibration driver at its support end, preferably, each support arm supports the vibration driver at the support end of the support arm.

[0144] In an embodiment, the pivot axis of each support arm extends in a plane perpendicular to the piling axis.

[0145] In an embodiment, the pivot axis of each support arm extends in a plane parallel to the piling axis.

[0146] In an embodiment, the pivot axis of each support arm extends in a radial direction relative to the piling axis.

[0147] In an embodiment, the pivot axis of each support arm extends perpendicular to the longitudinal axis of the support arm.

[0148] In an alternative embodiment, the floating support comprises a plurality of flexible support arms, each flexible support arm having a base end and a support end, wherein the flexible support arms support the vibratory drive at their support ends, preferably each flexible support arm supports a vibratory pile driver device at its support end.

[0149] In an embodiment, the support arm is tangent to a circle centred on the piling axis when viewed in top view.

[0150] In an embodiment, the support arm extends in a radial direction relative to the piling axis when seen in top view.

[0151] In an embodiment, the floating support comprises a plurality of linkage systems, each linkage system having a base linkage and a support linkage, wherein the linkage system supports the vibratory drive by means of its support linkage, preferably each linkage system supports the vibratory pile driver device via the support linkage, preferably such that the vibratory drive can move in a direction parallel to the pile driving axis.

[0152] In an embodiment, the floating support comprises a plurality of fins and slots extending parallel to the piling axis, such that the vibratory drive is movable in a direction parallel to the piling axis.

[0153] In an embodiment, the floating support comprises one or more elastic bodies, such as springs or cylinders, for elastically supporting the vibration driver in a direction parallel to the piling axis.

[0154] In an embodiment, the impact hammer is a gravity hammer, such as a falling weight hammer.

[0155] In an embodiment, the impact hammer is a forced impact hammer, preferably a hydraulic forced impact hammer.

[0156] In an embodiment, the hammer is a combination of a plurality of hammers, wherein each hammer is configured to transfer energy to the pile at a frequency, and wherein the hammers are adapted to operate sequentially.

[0157] In an embodiment, the pile driver includes an anvil configured to couple with a top end of the foundation pile column to transmit an axial pile driving force from the pile driver to the foundation pile column.

[0158] In another embodiment, the floating support is mounted to the anvil.

[0159] In an embodiment, the floating support is mounted to the top end of a monolithic pile (eg, comprising a ring mounted on the top end of the pile).

[0160] In an embodiment, the monolithic stud is configured to be engaged by the floating support, for example provided with radially extending teeth for cooperating with driving teeth of the floating support, and / or provided with a seat at the top end of the monolithic stud for accommodating the floating support.

[0161] The present invention also provides a vessel, such as a jack-up vessel, provided with a piling system for performing one or more piling methods disclosed herein.

[0162] A sixth aspect of the invention also provides a method of piling for vertically driving a hollow tubular pile having a vertical centerline, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile of an offshore wind turbine, into soil, such as into a seabed, using a piling system, preferably a piling system according to one or more aspects of the invention, wherein the method comprises the following steps:

[0163] - setting up the pile with the open foot in the seabed while supporting the pile above the horizontal plane in a radial direction using pile guides mounted on a vessel, such as a jack-up vessel;

[0164] - using an impact hammer to generate an axial piling force along a piling axis to drive the pile into the seabed, wherein the piling axis is aligned with the vertical centerline of the pile;

[0165] - using a vibratory drive to generate a torsional force about the pile driving axis to rotate the pile about a vertical centerline, thereby reducing friction between the pile and the seabed; and

[0166] - free movement of the vibrating drive along the piling axis to prevent direct transmission of impact forces from the hammer to the vibrating drive, and restrict, preferably prevent, free movement of the vibrating drive around the piling axis to enable direct transmission of torsional forces from the torsional drive to the hammer or the pile.

[0167] According to a seventh aspect, the present invention also provides a foundation pile installation method for conveniently driving a foundation pile into the seabed. According to the seventh aspect, a collapse zone is provided in the seabed before installing the foundation pile. The collapse zone promotes the movement of soil from under the foundation pile during the installation of the foundation pile and thus promotes the driving of the foundation pile into the seabed. Furthermore, with the method according to the seventh aspect, the soil around the foundation pile remains more or less intact, so that once the pile is driven into the seabed, an optimal friction between the seabed and the outside of the foundation pile can be obtained.

[0168] A seventh aspect provides a first foundation pile installation method, the installation method comprising preparing the seabed to facilitate driving a foundation pile, such as a foundation pile for supporting a wind turbine, into the seabed to an installation depth, wherein the foundation pile has a circumferential wall that forms a vertical foundation pile receiving area when the foundation pile is installed in the seabed; the method comprising:

[0169] - providing a central depression by excavating (e.g. drilling or scooping) a vertical cavity in the seabed, wherein the central depression is dimensioned such that a pile receiving zone is formed parallel to and around the depression with a soil transfer zone between the central depression and the receiving zone;

[0170] - positioning the foundation piles relative to the collapse zone and landing the bottom ends of the foundation piles on the seabed, thereby positioning the foundation pile receiving area around the central collapse zone and forming a soil transfer area between the central collapse zone and the receiving area;

[0171] - driving piles into the seabed, for example by hammering or vibrating the foundation piles at their top ends, thereby forming a containment zone parallel to the collapse zone and surrounding the soil transfer zone; and

[0172] -By driving the pile into the seabed, by pushing the soil away from under the circumferential wall of the foundation pile into the soil transfer zone, the vertical cavity in the central collapse zone is at least partially collapsed, and the soil is thereby pushed from the soil transfer zone into the collapse zone, the soil being transferred toward and into the central collapse zone facilitating the driving of the pile into the seabed.

[0173] In another embodiment, the method includes providing a lining along the interior of the vertical cavity of the central collapse zone, preferably while the vertical cavity is being excavated.

[0174] In another embodiment, the liner is configured to collapse into a central collapse zone by driving the foundation piles into the seafloor, the collapse preferably being caused at least in part by pushing soil away from beneath the circumferential walls of the foundation piles into the soil transfer zone.

[0175] In another embodiment, the method comprises removing the liner prior to driving the foundation pile into the sea floor, and preferably prior to landing the bottom end of the foundation pile into the sea floor.

[0176] In another embodiment, the method comprises preventing collapse of the collapse zone before driving the pile into the seabed by inserting a support body into the vertical cavity, wherein the support body has an outer support surface positioned against the wall of the cavity or against a liner provided along the wall of the cavity, and removing the support body before driving the foundation pile into the seabed and preferably before landing the bottom end of the foundation pile into the seabed.

[0177] In another embodiment, the method includes providing a grid of central collapsed areas for each facilitating driving of foundation piles into the sea floor and thereby forming a grid of foundation piles.

[0178] A seventh aspect also provides a seabed preparation process for preparing the seabed to facilitate driving a foundation pile, such as a foundation pile for supporting a wind turbine, into the seabed to an installation depth, wherein the foundation pile has a circumferential wall that forms a vertical foundation pile receiving area when the foundation pile is installed into the seabed, the method comprising:

[0179] -Providing an annular collapse zone around a central area by excavating (e.g., drilling or digging) one or more vertical cavities in the seabed, wherein the dimensions of the annular collapse zone are designed so that a pile accommodation zone is parallel to the collapse zone and is formed around the collapse zone, wherein a soil transfer zone is located between the central collapse zone and the accommodation zone.

[0180] In another embodiment, the method comprises the subsea preparation process according to item 9, the installation method further comprising:

[0181] - positioning the foundation pile relative to the collapse zone and landing the bottom end of the foundation pile into the seabed, thereby positioning the foundation pile receiving area around the annular collapse zone and forming a soil transfer area between the annular collapse zone and the receiving area; and

[0182] - driving piles into the seabed, for example by hammering or vibrating the foundation piles at their top ends, thereby forming a containment zone parallel to the collapse zone and surrounding the soil transfer zone; and

[0183] -By driving the pile into the seabed, by pushing soil away from under the circumferential wall of the foundation pile into the soil transfer zone, one or more vertical cavities in the annular collapse zone are at least partially collapsed, and soil is thereby pushed from the soil transfer zone into the collapse zone, the soil being transferred toward and into the annular collapse zone facilitating the driving of the pile into the seabed.

[0184] In another embodiment, the method includes providing a lining along the interior of each of the one or more vertical cavities of the annular collapse zone, preferably while excavating the one or more vertical cavities.

[0185] In another embodiment, one or more liners are configured to collapse into one or more vertical cavities in an annular collapse zone, respectively, by driving the foundation piles into the seabed, the collapse preferably being caused at least in part by pushing soil away from beneath the circumferential walls of the foundation piles into the soil transfer zone.

[0186] In another embodiment, the method includes removing one or more liners prior to driving the foundation piles into the seafloor, and preferably prior to landing the bottom end of the foundation piles on the seafloor.

[0187] In another embodiment, the method comprises preventing collapse of one or more cavities of the annular collapse zone before driving the pile into the seabed by inserting a support body into each of the one or more vertical cavities, respectively, wherein the support body has an outer support surface positioned against a wall of the corresponding cavity or against a liner provided along the wall of the corresponding cavity, and removing the support body before driving the foundation pile into the seabed and preferably before landing the bottom end of the foundation pile into the seabed.

[0188] In another embodiment, the collapse zone includes an annular cavity extending around the central zone, and wherein the annular cavity is provided with an interior for preventing collapse of the core zone, and wherein the outer liner is configured to collapse as a result of the foundation piles being driven into the seabed, or wherein the outer liner is removed from the cavity before the foundation piles are driven into the seabed.

[0189] In another embodiment, the method comprises providing a grid of annular collapsed areas for each facilitating driving of foundation piles into the sea floor and thereby forming a grid of foundation piles.

[0190] In another embodiment, the vertical cavity of the annular collapse zone has a depth similar to or greater than the installation depth.

[0191] In another embodiment, the method includes providing a collapsed zone including digging at least one annular vertical hole around a central zone.

[0192] In another embodiment, the width of the annular hole is greater than the width of the circular wall of the foundation pile, and wherein, when the collapse zone includes an inner liner and / or an outer liner, the width of the annular hole is greater than the combined width of the width of the circular wall of the foundation pile and the width of the inner liner and / or the outer liner, respectively.

[0193] In another embodiment, the method includes providing a collapsed zone comprising excavating a series of vertical holes distributed around a central zone.

[0194] In another embodiment, at least one of the one or more holes of the annular collapse area has a depth that is similar to or greater than the installation depth.

[0195] In another embodiment, one or more vertical cavities are filled with a slurry, such as a slurry of bentonite, to prevent complete collapse of the one or more vertical cavities before the foundation piles are driven into the seafloor.

[0196] In another embodiment, the liner is a corrugated material, wherein the grooves extend in the longitudinal direction of the liner.

[0197] In another embodiment, the collapse zone is located within at least 90%, preferably within 80%, of the radius of the foundation pile to facilitate landing of the foundation pile, so that a soil transfer zone is formed between the collapse zone and the foundation pile receiving area, and wherein the soil transfer zone has a width wide enough to prevent the collapse zone from affecting the trajectory of the foundation pile when landing or driving into the seabed. In an embodiment, the width of the soil transfer zone is at least twice the width of the circumferential wall of the foundation pile.

[0198] In another embodiment, the collapse zone includes a soil receiving space, and wherein the volume of the soil receiving space is greater than a volume included by the foundation pile receiving zone when the foundation piles are driven into the seafloor at the installation depth.

[0199] In another embodiment, the seabed preparation method is performed by a vessel, preferably a floating vessel, and wherein excavating one or more vertical cavities of the annular / central collapse zone includes controlling and / or supporting an excavation device for excavating one or more holes.

[0200] In another embodiment, the seabed preparation method, ie forming the collapsed zone in the seabed, is performed by a first vessel, and the foundation pile installation process, ie driving the foundation piles into the seabed, is performed by a second vessel.

[0201] In another embodiment, there are at least twenty-four hours between the seabed preparation process and driving the foundation piles into the seabed.

[0202] In another embodiment, the foundation pile has a diameter greater than 5 meters, preferably at least 8 meters, for example 10 meters or more.

[0203] In another embodiment, the foundation piles are driven into the seabed to an installation depth of at least 20 meters, preferably at least 30 meters, such as 40 meters.

[0204] In another embodiment, the circumferential wall of the foundation pile has a width of at least 5 cm, preferably a width of at least 8 cm.

[0205] In another embodiment, one or more shafts have a depth of at least 60% of the piling depth.

[0206] In another embodiment, the collapse zone comprises a plurality of shafts, and wherein the shafts have different depths, for example, one or more shafts have a depth of 60% of the piling depth, and one or more shafts have a depth of 90% of the piling depth.

[0207] In another embodiment, the foundation pile receiving area, soil transfer area, collapse area and optional central area are concentric.

[0208] It is proposed that the accommodation zone is preferably formed by driving the foundation pile into the seabed, whereby the radius of the accommodation zone is similar to the radius of the wall of the foundation pile and the depth of the accommodation zone is similar to the installation depth.

[0209] Furthermore, it is proposed that the actual boundary between the soil transfer zone and the foundation pile receiving zone is preferably determined by placing the foundation pile in a foundation pile receiving zone, the foundation pile receiving zone being located below the circumferential wall of the foundation pile and the soil transfer zone being located just inside the circumferential wall of the foundation pile.

[0210] The collapse zone comprises one or more holes which are shaped and / or positioned so that they collapse during the piling process. Thus, the collapse zone helps to move soil away from under the pile during the piling process and thus helps to drive the foundation pile into the seabed.

[0211] In an embodiment, the combined volume of the one or more holes in the collapse zone is similar to, and preferably greater than, the volume of the pile accommodation zone, i.e., the volume of soil that will be displaced by the foundation piles when they are driven into the seafloor to the pile installation depth. Thus, the volume of soil that will be displaced by the foundation piles can be accommodated in the holes in the collapse zone. It should be noted that in an embodiment, some of the soil that will be displaced by the wall of the foundation piles will be pushed in a radially outward direction and will therefore not move towards the collapse zone.

[0212] In an embodiment, the circumferential wall of the foundation pile is shaped to push the soil toward the collapse area. For example, the bottom surface of the circumferential wall can be inclined so as to mainly push the soil inwards.

[0213] In an embodiment, the collapse zone comprises an annular hole having a cross-section similar to or the same as the cross-section of the circumferential wall of the foundation pile.

[0214] Since the seventh aspect of the invention facilitates driving the pile into the seabed, the piling process may include a pile driver device, for example for hammering and / or vibrating, which engages the top end of the foundation pile. In this method, no devices such as drilling devices, digging devices, etc. are used at the bottom end of the foundation pile, which enables a less complicated piling process. Therefore, once the foundation pile is installed in the seabed, it is not necessary to remove the pile driver device at the bottom end of the foundation pile.

[0215] The containment area is the portion of the sea floor that will be replaced by the walls of the foundation piles.

[0216] The soil transfer zone is arranged between the collapse zone and the accommodation zone.

[0217] Typically, the hole created for the collapsed area is a narrow hole. The hole has a greater depth than its width and length. There can be many types of shapes, i.e. cross-sections, such as rectangular holes, or circular holes, annular holes.

[0218] One or more holes are distributed in the collapsed area. In an embodiment, the collapsed area comprises a plurality of circular holes distributed in an annular area, for example distributed in two circles of holes, wherein the holes are evenly distributed in each circle.

[0219] A seventh aspect of the present invention facilitates driving the pile into the seabed, thereby enabling an effective piling process. In addition, since less force is required to drive the pile into the seabed, less noise is generated during the piling process.

[0220] According to an eighth aspect, the present invention also provides a pile installation device and a method for installing a pile, preferably by using the pile installation device according to the fifth aspect of the present invention.

[0221] Offshore wind turbines are usually mounted on foundation piles, also called monopiles, i.e. hollow tubular piles with a vertical centerline, a top end and an open foot end. These foundation piles are provided with a transition piece, on which the tower of the wind turbine is mounted. With the trend towards increasing wind turbine capacity, and towards providing larger wind turbines on taller towers, these foundation piles used have increased in size and mass.

[0222] Typically, wind turbine foundation piles are driven into the seabed using a hammer mounted on the top of the foundation pile. This pile driving process creates a lot of noise, which is harmful to marine life. It would therefore be beneficial if an alternative method could be used to drive the piles into the seabed, particularly for installing larger sized foundation piles.

[0223] According to an eighth aspect, the present invention is directed to an alternative for installing a wind turbine foundation pile into the seabed, more particularly to an alternative for driving a foundation pile into the seabed using a hammer. The present invention is also directed to a pile installation device configured for efficiently lowering a foundation pile into the seabed. The present invention is also directed to a pile installation device configured for drilling a hole for receiving a foundation pile.

[0224] The pile installation device is configured for supporting the pile and for drilling a hole beneath the pile to enable the pile to be lowered into the seabed.

[0225] The pile installation device of the present invention comprises a supporting frame, a pile guide, a pile liner and a pile drilling machine.

[0226] The support frame comprises a pile guide for supporting the pile in an upright position and for guiding the pile as it is lowered into the sea bed.

[0227] The support frame is provided with three or more feet, or for example with a single annular foot, for supporting the pile guide and hence the foundation pile received therein in an upright position on the seabed. The feet may be mounted on legs extending in a radial direction away from the pile guide.

[0228] Preferably, the pile is configured to adjust the position of the pile guide relative to one or more feet, and / or to adjust the individual position of the feet relative to the pile guide, so that the pile guide can be set in an upright position. Thus, the pile guide can be set in an upright position to support the pile in a vertical position when the seabed surface is uneven and / or not level.

[0229] In an embodiment, the pile guide comprises a plurality of pile engagement devices configured to engage an outer surface of a foundation pile, the pile engagement devices being individually positionable relative to the support frame to adjust the position of a foundation pile supported in the pile installation arrangement.

[0230] Furthermore, the movable pile engagement means may be configured to integrally take into account the diameter variation of the foundation pile.For example, a foundation pile typically comprises a wider foot section and a narrower head section.

[0231] The pile support is also provided with a tubular pile liner and a pile drilling rig.

[0232] During use, the pile is housed inside and concentric with the pile liner. Preferably, the inside of the pile liner is provided with spacers to position the pile inside the pile liner so that there is a space between the outwardly facing surface of the pile and the inwardly facing surface of the pile liner. The space between the foundation pile and the pile liner can be used to remove bored material from the lower end of the pile.

[0233] During the drilling process, both the pile liner and the pile are lowered into the seabed, more particularly into the annular pile hole drilled by the pile drilling rig.

[0234] The pile drilling rig is preferably annular, ie comprises a central opening wide enough to accommodate the pile. Thus, the pile can be moved along the outside of the pile.

[0235] The drill bit may include a plurality of drill bits.

[0236] In an embodiment, the drill comprises an annular frame with a central drilling axis, the annular frame being provided with a plurality of drill bits supported at regular intervals along the circumference of the frame. The drill bits are arranged with their axes parallel to the central axis of the annular frame. Thus, in use, the drilling rig is set up so that the drilling axis is parallel to, and preferably coincides with, the central axis of the monolithic pile to be lowered into the seabed. The drilling direction is parallel to the drilling axis, in a downward direction into the seabed.

[0237] In an embodiment, the drilling rig is configured to move the annular drill frame around a central drilling axis. Thus, the drill head moves along at least a portion of the circumference of the pile. In an embodiment, the drilling rig is configured to move back and forth, for example, along a portion of the circumference of the pile.

[0238] In an embodiment, the pile drilling rig comprises a driving module for driving a drill bit. The drilling rig module may be arranged on top of an annular drilling frame supporting a plurality of drill bits.

[0239] In an embodiment, the pile drilling rig is powered by a fluid, such as a liquid or a gas such as air. In an embodiment, a power source for driving the pile drilling rig is mounted on the pile support. In an alternative embodiment, the power source is mounted on a support vessel. The power source can be connected to the pile drilling rig via one or more cables and / or pipes (e.g., pipes for conveying fluid for driving the pile drilling rig), which are guided to the pile drilling rig via a space between the pile and the pile liner. In an embodiment, the pile liner is provided with one or more pipelines for directing air to the pile drilling rig so as to provide power for the pile drilling rig.

[0240] In an embodiment, the drilling rig is mounted to the pile liner so that it moves together with the pile liner. In this embodiment, the pile driver can be removed from the pile hole by lifting the pile liner upwards.

[0241] In an embodiment, the pile drilling rig removes a cable connected to the pile drilling rig, the cable extending upwardly through the space between the pile liner and the foundation pile for lifting the pile drilling rig out of the pile hole after the drilling process is completed.

[0242] Additionally, or alternatively, the drilling rig may be mounted to the exterior of the pile. In an embodiment, the foundation pile is provided with a coupling means, such as an opening or a mounting, which can be engaged by the drilling rig. For example, to provide a clamp for the drilling rig and enable the drilling rig to move in a circular direction relative to the pile during the drilling process.

[0243] In an embodiment, the drilling rig is provided with an electromagnet to temporarily secure the drilling rig to the pile.

[0244] In addition, or as an alternative to the drill bit, the drilling rig may be provided with water jets for drilling the pile holes.

[0245] In an embodiment, the pile is provided with injection openings at the lower end, ie, the end that descends into the seabed. Through these openings, fluid can be injected at the lower end of the pile to form the pile hole.

[0246] Preferably, material loosened by the drill bit and / or water jets is transported upwardly by the flow of fluid in the space between the foundation pile and the pile liner.

[0247] According to an eighth aspect, the present invention also provides a method for installing a wind turbine foundation pile, preferably using the pile installation device according to the present invention.

[0248] First, the pile installation device is set up on the seabed. The legs of the pile installation device are preferably anchored in the seabed, for example, one or more spikes are provided, which are driven into the seabed. Furthermore, if necessary, the relative positions of the legs and the pile guide are adjusted to position the pile guide in an upright position, i.e., a position for supporting the pile guide in an upright position, i.e., a vertical position.

[0249] Preferably, when the pile guide is set up, the pile liner and the pile drilling machine are already accommodated in the pile guide. As an alternative, after the pile guide has been set up on the seabed, the pile liner and / or the pile driver are installed in the pile guide.

[0250] The pile liner is concentrically received in the pile guide, and the pile drilling rig is located at the lower end of the pile liner on the seabed.

[0251] The pile guide is now ready to receive the pile. It is proposed that the pile installation device may be set up by a vessel other than the vessel transporting the pile. For example, a plurality of pile drivers may be set up by the first vessel at different locations. Thus, a vessel configured for transporting and / or for erecting foundation piles and / or for lifting foundation piles into the pile installation device may be provided. For example, a support vessel may be used to set up the pile installation device, a barge may be used to transport the foundation piles to the pile installation device, and a crane vessel may be used to erect the foundation piles and to lift the foundation piles into the pile installation device.

[0252] After the pile installation device is set up on the seabed, the foundation pile is lifted into the pile guide and into the pile liner held in the pile guide. The pile installation device may be provided with one or more centralizers at the top end for guiding the lower end of the pile into the pile guide and preferably aligning the pile with the pile liner accommodated in the pile guide. If present, the pile engagement device may engage the portion of the pile that is not accommodated in the pile liner, i.e., the portion of the pile that extends above the pile liner.

[0253] Preferably, the pile installation device is configured to support the foundation pile in an upright position. In an alternative embodiment, for example during the first part of the pile installation process, the foundation pile is also supported by a crane. In such an embodiment, a crane vessel supporting the pile may support the pile until enough of the pile is lowered into the seabed so that the pile installation device can support the pile in an upright position.

[0254] The inner side of the pile liner is provided with a spacer for positioning the foundation pile in the center of the pile liner. By lowering the pile into the pile guide, more particularly by accommodating the pile in the pile liner, a space is created between the pile and the pile liner. The pile drilling rig is located at the lower end of this space. The space between the pile liner and the foundation pile is used to transport drilling material, such as drill cuttings, upwards and away from the pile drilling rig.

[0255] Once the foundation pile is received in the pile liner and the pile is supported in an upright position, an annular pile hole is drilled at the lower end of the foundation pile and the pile liner using a pile drilling machine. The pile drilling machine gradually drills a vertical annular space for receiving the foundation pile and the pile liner. Both the pile and the pile liner follow the pile drilling machine, and therefore, the annular space between the foundation pile and the pile liner follows the pile drilling machine. Therefore, the drilled material can be continuously transported upwards via the annular space and leaves the pile drilling machine.

[0256] In an embodiment, the bored material is removed at the top end of the annular space via one or more outlets and transported, for example, to a support vessel. On the support vessel, the bored material can be cleaned, i.e. the drilling fluid can be removed, after which the bored material can be used to fill the space between the foundation pile and the seabed once the pile liner and the pile drill are removed.

[0257] When the drilling process is completed, the pile liner and the pile drilling rig are lifted up out of the pile hole. Thus, the pile remains in the seabed.

[0258] In an embodiment, the space created by removing the pile drill and pile liner can be filled, such as cemented. For example, when the pile drill and pile liner are lifted out of the pile hole, the space below them can be filled with cement and / or materials removed during the drilling process. Filling this space can further enhance the contact between the seabed and the foundation pile, and thus can improve the stability of the pile.

[0259] According to an eighth aspect, the present invention provides a foundation pile column installation device, the foundation pile column installation device comprising:

[0260] - a support frame configured to be set up on the sea bed, the support frame preferably comprising three or more adjustable feet for adjusting the position of the support frame on the sea bed;

[0261] a pile liner for receiving the pile and for moving with the pile when the pile is lowered into the seabed, wherein the pile liner is preferably configured to form a space between the liner and the foundation pile received in the liner;

[0262] a pile drilling rig, preferably an annular pile drilling rig, arranged at the lower end of the pile liner for drilling pile holes capable of receiving the liner and the foundation piles received in the liner; and

[0263] - A pile guide, which is retained in the supporting frame and is used to guide the pile and / or pile liner in which the foundation pile is accommodated during the pile installation process, ie when the pile and pile liner are lowered into the seabed.

[0264] In an embodiment, the pile guide comprises an upper section and a lower section, the upper section being provided with one or more pile engagement devices for engaging and guiding a foundation pile received in the pile installation device, the lower section being configured for guiding the pile liner as it is lowered into the seabed together with the foundation piles during the installation process, and thereby guiding the foundation pile received in the pile liner.

[0265] In an embodiment, the pile drilling rig is fixed to the pile liner so that after the drilling process, the pile liner and the pile drilling rig can be removed as an integral piece.

[0266] In an embodiment, the pile liner is provided with one or more pipelines for conducting a power fluid to the pile drilling rig. In yet another embodiment, the pile liner is provided with one or more pipelines for conducting cement under the pile drilling rig so that the space created can be cemented when the pile liner and the pile drilling rig are removed from the pile hole after the drilling process. Thus, the pile hole can be cemented at the same time as the liner and the drill bit are removed, which reduces the chance of the space collapsing before being cemented.

[0267] It should be understood that the first, second, third, fourth, fifth, sixth, seventh and / or eighth aspects may be combined in various combinations, for example to optimize a pile driving method and / or a pile driving system. For example, the floating support of the sixth aspect of the invention may be used in a pile driving system according to the first aspect of the invention, and the torsional vibration driver of the first aspect of the invention may be implemented as a vibration driver of the sixth aspect of the invention. Furthermore, components discussed in the context of the vibration driver of the sixth aspect of the invention, such as a plurality of support arms connecting the vibration driver to the anvil of a hammer, may be incorporated into the torsional vibration driver of the first aspect of the invention, for example to connect the floating support to the top of a pile column. Furthermore, for example, features discussed in relation to the sixth aspect may be combined with the first aspect of the invention and vice versa. Furthermore, for example, the floating support of the vibration driver connected to the impact hammer according to the sixth aspect of the invention may be used, for example, in a pile driving method according to the fourth aspect of the invention, wherein the floating support is combined with a drop weight pile driver device engaged on the top of the pile column and at least one vibration pile driver device of the fourth aspect of the invention to provide a pile driving system. Furthermore, for example, the method according to the fourth aspect of the present invention may be combined with the method according to the seventh aspect, i.e., the pile driving method according to the fourth aspect of the present invention may be used to drive piles into the seabed, wherein the seabed is provided with a collapsed zone according to the seventh aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0268] Various aspects will now be described with reference to the accompanying drawings. In the drawings:

[0269] Figure 1 Schematically illustrating a second aspect of the present invention,

[0270] Figure 2 Schematically illustrating a third aspect of the present invention,

[0271] Figure 3 A fourth aspect of the present invention is schematically shown,

[0272] Figure 4A , Figure 4B A fifth aspect of the present invention is schematically shown,

[0273] Figure 5 a schematic side view in partial section showing an exemplary embodiment of a piling system 201 according to the sixth aspect of the invention on a pile 202;

[0274] Figure 6 Shows Figure 5 A top view of a portion of a piling system;

[0275] Figure 7 The first working state is shown Figure 5 A piling system in which the elastic body 217 is compressed and the support arm is pivoted downward;

[0276] Figure 8 Shows the second working state Figure 5 A piling system in which the elastic body 217 is extended and the support arm is pivoted upward;

[0277] Fig. 9 A first aspect of the present invention is schematically illustrated;

[0278] Fig.10 showing a cross-sectional side view of an exemplary embodiment of a pile installation arrangement according to an eighth aspect of the invention; and

[0279] Figures 11A-11F Shows the use of Fig.10 Different steps of the method according to the eighth aspect of the invention of a pile installation device, wherein the pile installation device is shown in cross section. DETAILED DESCRIPTION

[0280] exist Figure 1 In the figure, reference numeral 1 denotes a hollow tubular pile 1 having a vertical centerline 2, a top end 3 and an open foot end 4. The pile 1 is to be driven vertically into the soil, for example into the seabed. For example, the pile is a relatively large diameter pile having an outer diameter at the open foot end of at least 5 meters, for example 7 meters or more. For example, the pile is a so-called monolithic pile of an offshore wind turbine.

[0281] Practical embodiments of the monolithic pile currently envisaged include monolithic piles 1 having a diameter between 5 and 12 meters and a length between 60 and 120 meters. In an embodiment, the wall thickness of the pile 1 is greater than 10 centimeters. For example, the pile 1 may have a mass greater than 1000 tons, such as greater than 2000 tons, or even greater than 3000 tons.

[0282] In a practical embodiment, the pile 1 is a steel pile, for example consisting of annular segments welded end to end, each annular segment consisting of arc-shaped segments welded to each other to form an annular shape.

[0283] The pile 1 may comprise, for example, a tapered or conical section between a lower pile section of larger diameter and a pile top section of smaller diameter.

[0284] In a second aspect of the invention, a piling system 10 is used, which comprises a plurality of vibrating pile driver devices 11, 12, 13, 14, 15, 16, 17, 18. Thus, in this example, eight vibrating pile driver devices are used, but other numbers of vibrating pile driver devices may be used, such as four, six, ten, etc.

[0285] A plurality of vibratory pile driver devices 11 - 18 are arranged in a circular array and are engaged on the top end 3 of the pile 1 independently of each other.

[0286] Each vibrating pile driver device 11-18 is configured to apply an alternating vertical force at a corresponding vibration frequency along a working line associated with the pile driver device. For example, each device includes one or more sets of rotating eccentric weights that rotate around an associated axis. For example, a hydraulic motor drives the eccentric weights.

[0287] The alternating vertical force combination produces a composite vertical force having a composite vertical force working line. In the prior art method, the composite vertical force working line coincides with the center line 2.

[0288] In the inventive method of the second aspect of the present invention, a plurality of vibratory pile driver devices 11-18 are operated to apply their alternating out-of-phase vertical forces in such a way that the resultant vertical force F deviates from the vertical centerline 2 of the tubular pile column and travels about the vertical centerline. Figure 1 The purpose of this method is to effectively reduce the surface friction between the pile 2 and the soil.

[0289] For example, the pile driver devices 11-18 are each directly connected, for example clamped to the pile 1, for example clamped to its top end. In another embodiment, the pile driver devices 11-18 are integrated in a common carrier, for example so that all devices are lifted onto the top end of the pile by a crane.

[0290] like Figure 1 As shown, these pile driver devices 11-18 that generate a resultant vertical force F that deviates from the vertical centerline 2 of the tubular pile 1 and travels about the vertical centerline can be all the devices used to drive the pile 1 into the soil. In another embodiment, one or more additional pile driver devices are used simultaneously. For example, a single (high-power) drop-weight pile driver device can also be used, such as Figure 2 In another example, one or more additional vibratory pile driver devices are used, which have a combined force that coincides with the centerline of the pile, such as Figure 2 shown.

[0291] In a practical embodiment, the pile driving system 10 includes a controller that monitors the phase of each of the plurality of vibrating pile driver devices 11-18 that are operated to apply their alternating out-of-phase vertical forces, and that also enables out-of-phase operation of the adjustment devices 11-18. The controller may also enable, for example, adjustment of the vibration frequency, as is known in the art.

[0292] In a practical embodiment, the movement of the top end 3 of the pile 1 in the horizontal plane is monitored, for example to monitor and / or control the operation of the pile driver device 11-18, which generates a resultant vertical force F that deviates from and travels around the vertical centerline 2 of the tubular pile. For example, such monitoring is done using (laser) distance measuring equipment and / or inertial based measuring equipment or the like.

[0293] Figure 1 It can also be considered as a schematic diagram of another method according to the second aspect of the present invention, wherein the pile driving system 10 includes a plurality of drop weight pile driver devices 11-18 engaged independently of each other on the top end of the pile column in a circular array. Here, each pile driver device 11-18 is configured to transfer energy from a corresponding drop weight to the top of the pile column at a corresponding frequency along the working line associated with the pile driver device, and the energy transfer of the pile driver devices is combined to produce a resultant vertical force having a resultant vertical force working line.

[0294] According to a second aspect of the invention, a plurality of drop weight pile driver devices 11-18 are operated to perform their respective out-of-phase energy transfers in such a manner that the resultant vertical force is offset from and travels about the vertical centre line of the tubular pile.

[0295] It will be appreciated that such operation is envisaged to result in a reduction in surface friction.

[0296] For example, the falling weight devices are each embodied as a (hydraulic accelerated) falling weight hammer device, as is customary for driving (offshore) piles.

[0297] Reference Figure 2 The third aspect of the present invention is discussed.

[0298] A third aspect of the invention relates to a piling method for driving a hollow tubular pile 1 having a vertical centre line 2, a top end 3 and an open foot end vertically into soil, for example into the seabed, for example the pile is a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, for example a monolithic pile for an offshore wind turbine.

[0299] A pile driving system 20 is used which includes one or more vibratory pile driver devices 21, 22 engaged on the top end of the pile column, each of the vibratory pile driver devices 20, 21 being configured to apply an alternating force at a respective vibration frequency along a working line associated with the pile driver device.

[0300] According to a third aspect of the invention, one or more vibrating pile driver devices 21, 22 are constructed and operated with a horizontal working line so that a lateral vibrating force Fh is applied to the top end 3 of the pile 1. The top end of the pile is thus effectively oscillated in a vertical plane to reduce surface friction.

[0301] A third aspect of the invention is based on the recognition that, particularly for larger diameter piles, effectively inducing torsional vibrations may prove impractical. For example, by using a circular arrangement of such pile driver devices operating in unison to produce controlled lateral vibrations of the top end of the pile, it may be feasible to controllably oscillate the pile 1 in a vertical plane even for larger diameter piles.

[0302] Here two vibrating pile driver devices 21, 22 are shown mounted at diametrically opposed positions on the top end of the pile, the pair of devices 21, 22 being constructed and operated with a horizontal working line, such as a common working line, so that a lateral vibration force Fh is applied to the top end of the pile. One or more additional vibrating pile driver devices may be mounted at other positions on the top end of the pile and have parallel working lines to assist in inducing lateral vibrations.

[0303] In order to provide the vertical pile driving force, it is envisaged that one or more additional pile driver devices are combined with one or more devices 21, 22. Here a single (hydraulic accelerated) drop weight hammer device 23, commonly used for the driving of (offshore) piles, is shown for providing (most of) the vertical pile driving force. The device 23 has a sleeve 24 mounted on the top end of the pile 1. The (accelerated) drop weight 23a falls on an anvil 24a directly connected to the sleeve and resting on the top of the pile 1.

[0304] Reference Figure 3 The fourth aspect of the present invention is discussed.

[0305] A fourth aspect of the invention relates to a method for driving a pile vertically into soil, e.g. into the seabed, a hollow tubular pile 1 having a vertical centre line 2, a top end 3 and an open foot end, e.g. the pile is a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, e.g. a monolithic pile for an offshore wind turbine.

[0306] A pile driving system 20' is used which comprises a drop weight pile driver device 23 engaged on the top end 3 of the pile and configured to transfer energy from a respective drop weight 23a along a vertical working line at a respective frequency, here via anvil 24a, to the top of the pile.

[0307] In another embodiment, the system disclosed in WO2020153838 is used. In this document, a system is described that allows the generation of huge pile driving energies to drive a monolithic pile into the soil. Typically, a very large mass that falls (not accelerated except by gravity) is used here. For example, the energy transfer lacks mechanical impact energy transfer.

[0308] A fourth aspect of the invention proposes a pile driving method, wherein a pile driving system is used, the pile driving system also comprising at least one vibrating pile driver device 21, 22, 25, 26 which is different from the drop weight pile driver device 23 and which is engaged on the top end of the pile column.

[0309] Each vibrating pile driver device 21, 22, 25, 26 is constructed and operated to operate simultaneously with the operation of at least one drop-weight pile driver device 23 to apply an alternating force Fh, Fv at a respective vibration frequency along a working line associated with the pile driver device 21, 22, 25, 26.

[0310] Therefore, in the inventive method of the fourth aspect, a combination of systems is used, one system is based on the presence of one or more drop-weight pile driver devices 23 engaged on the top end of the pile, for example to provide all or most of the vertical piling energy, and the other system is based on the presence of one or more vibrating pile driver devices 21, 22, 25, 26 that are different from the one or more drop-weight pile driver devices 23, and the one or more vibrating pile driver devices 21, 22, 25, 26 can actually be mainly used to reduce the surface friction between the pile and the soil, for example without generating vertical piling energy, or only generating less vertical piling energy than the one or more drop-weight pile driver devices 23.

[0311] By way of example it is shown that the vibratory pile driver arrangement 21, 22 provides the above mentioned lateral vibration of the third aspect of the invention.

[0312] Vibratory pile driver devices 25, 26 are shown providing vertical vibration.

[0313] As described herein, vertical and horizontal vibrations are primarily used to reduce surface friction between the pile and the soil. For example, one or more vibrating pile driver devices 21, 22, 25, 26 provide vibrations at a higher frequency than the operation of the drop weight pile driver device 23 engaged on the top end of the pile 1.

[0314] Reference Figure 4A , Figure 4B , discussing the fifth aspect of the present invention.

[0315] A fifth aspect of the invention relates to a piling method for driving a hollow tubular pile 1 having a vertical centre line, a top end 3 and an open foot end vertically into soil, for example into the seabed, for example the pile is a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, for example a monolithic pile for an offshore wind turbine, wherein a piling system is used.

[0316] The pile driving system comprises: a drop weight pile driver device 23, which is engaged on the top of the pile column 1, and the drop weight pile driver device 23 is configured to transfer energy from the corresponding drop weight to the top of the pile column at a corresponding frequency along the vertical working line,

[0317] An energy transfer assembly 30 configured to transfer energy from the falling weight 23a to the top end of the pile 1 .

[0318] A fifth aspect of the present invention provides a pile driving method in which the energy transfer assembly 30 is constructed and operated to convert a portion of the energy from the falling weight 23a into a torsional stress wave applied to the top end 3 of the pile 1.

[0319] A fifth aspect of the invention is based on the recognition that torsional stress waves (which can also be considered as acoustic waves) can be generated from axial, vertically travelling waves, such as can be observed when the energy from a falling weight travels to the top of a pile. In practice, a small portion is then converted into torsional stress waves, the remainder continuing as axial, vertical waves.

[0320] In an embodiment, as schematically shown, the energy transfer assembly 30 comprises a tubular section 31 through which the energy from the falling weight 23a travels to the top end 3 of the pile, wherein the section 31 has a helically increasing wall thickness portion 32 which results in the generation of a torsional stress wave. The wave Figure 4B This is schematically shown in FIG. 1 and denoted by “W”. The section 31 is connected to the top of the pile so that the torsional stress wave and the axial and vertical stress wave are transmitted to the top of the pile 1 .

[0321] According to the sixth aspect of the present invention, the pile driving system 201 includes an impact hammer 203 , a vibration driver 204 and a floating support 205 .

[0322] The impact hammer is mounted on the top end of a hollow tubular pile 202 having a centerline with a vertical centerline 206, a top end 207 and an open foot end that vertically enters the soil (not shown), such as the seabed. The pile 202 is a larger diameter pile having an outer diameter of about 12 meters at the open foot end and is a single-piece pile for supporting an offshore wind turbine.

[0323] The hammer 203 is configured to generate an axial pile driving force along a pile driving axis 208. Since the hammer is mounted on the pile 202, the pile driving axis 208 is aligned with the vertical centerline 206 of the pile 202.

[0324] In the embodiment shown, the hammer comprises an anvil 209 by which the hammer is mounted on the top end of the pile.

[0325] The vibration drive 204 is configured to generate an alternating force about a pile driving axis 208 at a vibration frequency to vibrate the pile 202 about a vertical centerline 206 and reduce friction between the pile and the seafloor.

[0326] In the illustrated embodiment, the vibratory drive 204 is configured as a ring frame 210 that includes a plurality of vibratory pile driver devices 211. The ring frame is depicted in partial cross-section.

[0327] In the illustrated embodiment, the vibration driver 204 is mounted to the hammer, and more specifically to the anvil 209 of the hammer.

[0328] The floating support is configured to allow free movement of the vibration driver 204 along the piling axis to prevent impact forces from being directly transmitted from the impact hammer to the vibration driver, and to restrict, preferably prevent, free movement of the vibration driver around the piling axis to enable torsional forces to be directly transmitted from the torsional driver to the impact hammer or pile.

[0329] In the particular embodiment shown, the floating support comprises a plurality of support arms 212, Figure 5 Only one support arm is shown in the figure. A plurality of support arms 212 each have a base end 213 and a support end 214. The support arm is provided with a pivot axis 215 at its base end and supports a vibration driver, in the illustrated embodiment, an annular frame of the vibration driver 204 at its support end. In the illustrated embodiment, the support arm is pivotally mounted to the anvil at its base end and to the frame of the vibration driver at its support end. Furthermore, in the illustrated embodiment, the support arm extends substantially tangentially to a circle centered about the center line. Figure 6 A schematic top view of the anvil and three support arms of the floating support is shown. Furthermore, in the embodiment shown, the floating support comprises a plurality of elastic bodies 217, which in the embodiment shown are implemented as hydraulic cylinders connected to gas buffers. The elastic bodies 217 are mounted between the anvil 209 and the annular frame 210 of the floating support.

[0330] The elastic body thus allows the vibration driver to move freely along the pile driving axis to prevent the impact force from being directly transmitted from the impact hammer to the vibration driver.

[0331] In the embodiment shown, the elastomer supports the annular frame so that when the system is stationary (as depicted), the support arms are in a substantially horizontal position. The elastomer can extend to compensate for sudden acceleration of the impact hammer, and can be compressed to decelerate the annular frame when the annular frame follows the pile in a downward direction but the pile has slowed down or stopped. Thus, the floating support prevents excessive acceleration and deceleration of the vibratory drive during the pile driving process.

[0332] The support arm limits, preferably prevents, free movement of the vibration drive about the pile driving axis, thus enabling a direct transmission of torsional forces from the torsional drive to the hammer and, via the hammer, directly to the pile.

[0333] Reference Fig. 9 A first aspect of the present invention is discussed.

[0334] A first aspect of the invention relates to a piling system for driving a hollow tubular pile 301 having a vertical centerline 302, a top end 303 and an open foot end vertically into soil, for example into the seabed, for example the pile is a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, for example a monolithic pile of an offshore wind turbine.

[0335] A pile driving system 320 is used. In the embodiment shown, the pile driving system 320 comprises a hammer device 323 implemented as a drop weight pile driver device. The hammer device is engaged on the top end 303 of the pile. The drop weight pile driver device is configured to transfer energy from a corresponding drop weight 323a along a vertical working line at a corresponding frequency, here via anvil 324a, to the top of the pile.

[0336] A first aspect of the invention proposes a piling system, wherein a piling system further comprising a torsional vibration drive 304 comprising at least one vibrating pile driver device is used. In the embodiment shown, the torsional vibration drive 304 is distinct from the hammer device 323 and is engaged on the top end of the pile column.

[0337] The torsional vibration drive 304 is configured to generate an alternating force Fa about the piling axis 305 at a vibration frequency to vibrate the pile 301 about the vertical centerline 302 and reduce friction between the pile and the seabed.

[0338] In the embodiment shown, the torsional vibration drive 304 comprises four vibrating pile driver devices 321, 322, 325, three of which are shown, which are configured in a ring around the pile. In addition, in the embodiment shown, the torsional vibration drive 304 is configured as a ring frame, and the ring frame 310 comprises four vibrating pile driver devices 321, 322, 325.

[0339] Each vibrating pile driver device 321, 322, 325 is constructed and operated simultaneously with the operation of at least one drop-weight pile driver device 323 to apply an alternating force Fa at a respective vibration frequency about a pile driving axis 305 coinciding with the central longitudinal axis of the pile column.

[0340] Thus, in the inventive method of the first aspect, a combination of systems is used. One is based on the presence of at least one hammer device 323 engaged on the top end of the pile, for example to provide all or most of the vertical piling energy, and the other is based on the presence of a torsional vibration drive 304. The torsional vibration drive 304 comprises one or more vibrating pile driver devices 321, 322, 325, which are actually used to reduce the surface friction between the pile and the soil, and do not generate vertical piling energy.

[0341] By way of example it is shown that the vibrating pile driver devices 321 , 322 , 325 provide the above-mentioned alternating force Fa about the piling axis at a corresponding vibration frequency.

[0342] As described herein, horizontal vibrations about the pile driving axis are primarily used to reduce surface friction between the pile and the soil. For example, one or more vibrating pile driver devices 321, 322, 325 provide vibrations at a higher frequency than the operation of the drop weight pile driver device 323 engaged on the top end of the pile 301.

[0343] Thus, in the embodiment shown, the hammer device 323 is mounted on the top end of a hollow tubular pile 301 having a vertical centerline 302, a top end 303 and an open foot end that extends vertically into soil (not shown), such as into the seabed. The pile 301 is a larger diameter pile having an outer diameter of approximately 12 meters at the open foot end and is a monolithic pile for supporting an offshore wind turbine.

[0344] In the embodiment shown, the hammer device 323 is implemented as an impact hammer. The hammer device 323 is configured to generate an axial pile driving force along a pile driving axis 305. Since the impact hammer is mounted on the pile column 301, the pile driving axis 305 is aligned with the vertical centerline 302 of the pile column.

[0345] Furthermore, in the embodiment shown, the torsional vibration driver 304 is connected to the pile 301 via a floating support. The floating support is disposed between and connected to the annular frame of the torsional vibration driver and the foundation pile. The floating support is configured to allow the torsional vibration driver to move freely along the pile axis 305 to prevent energy from being directly transferred from the hammer device 323 to the torsional vibration driver, and to restrict, preferably prevent, free movement of the torsional vibration driver around the pile axis to enable torsional forces to be directly transferred from the torsional vibration driver to the hammer device or the pile.

[0346] It is contemplated that the floating support may be implemented as the floating support discussed in relation to the sixth aspect of the present invention, and for example in Figures 5 to 8 Shown in.

[0347] The floating support is configured to allow free movement of the torsional vibration driver along the piling axis to prevent direct transmission of impact forces from the impact hammer to the torsional vibration driver, and to restrict, preferably prevent, free movement of the torsional vibration driver around the piling axis to enable direct transmission of torsional forces from the torsional driver to the impact hammer or the pile.

[0348] In an embodiment, the floating support comprises a plurality of support arms, each support arm having a base end and a support end connecting the annular frame of the torsional vibration driver to the pile. The support arms are pivotally mounted at their base ends to the top ends of the piles and pivotally mounted at their support ends to the frame of the torsional vibration driver.

[0349] In another embodiment, the support arm extends substantially tangentially to a circle centered on the pile driving axis, for example similar to Figure 6 In addition, the floating support preferably comprises a plurality of elastic bodies, not shown in the figure, for example implemented as hydraulic cylinders connected to gas buffers. The elastic bodies are installed, for example, between the pile and the annular frame of the floating support to dampen the vertical movement of the torsional vibration drive relative to the hammer device.

[0350] Fig.10 A cross-sectional side view of an exemplary embodiment of a pile installation device 101 according to the eighth aspect of the invention is shown. Figures 11A-11F Shows the use of Fig.10 Different steps of the method according to the eighth aspect of the invention of a pile installation device, wherein the pile installation device is shown in cross section.

[0351] The pile installation device 101 includes a support frame 102 , a pile liner 103 , a pile drilling machine 104 and a pile guide 105 .

[0352] Fig.11A The pile installation arrangement is shown set up on the seabed ready to receive the foundation piles. Fig. 11B Shows Fig.11A A pile installation device for supporting the foundation pile 106. Fig. 11C The foundation piles are shown being lowered into the sea floor. Fig.11E The pile liner 103 and pile drill rig 104 are shown lifted from the pile hole, and the foundation pile 106 lowered into the installation position. Fig.11F The foundation installation arrangement 101 , more specifically the support frame 102 and the pile guides 105 , are shown removed (ie lifted), thereby leaving the foundation piles in the installed position.

[0353] The support frame 102 is configured to be erected on the sea floor 108. Fig.10 In the exemplary embodiment of the pile installation device 101 shown, the support frame 102 is provided with three legs 107, of which two legs are shown, for laterally supporting the foundation piles. The legs 107 are provided with spikes to secure their position on the seabed.

[0354] The pile liner 103 for receiving the pile is configured to form a space between the liner and the outer surface 109 of the foundation pile 106 received in the liner. In the particular embodiment shown, the liner is provided with a spacer 111 which centers the foundation pile 106 in the pile liner 103, thereby forming a space between the pile and the pile liner.

[0355] In an embodiment, the spacers may be adjustable so that they enable different sized piles to be centered in the pile liner.

[0356] A pile guide 105 is held in the support frame 102, in the embodiment shown, and is configured to guide the foundation pile 106 and the pile liner 103. It is proposed that during the drilling process, the pile liner 103 is moved together with the foundation pile 106 into the pile hole 112 formed by the pile drilling machine 104. This Fig. 11C and 11D Described in.

[0357] In the embodiment shown, the pile guide 105 comprises an upper section 105a and a lower section 105b. The upper section 105a of the pile guide is provided with one or more pile engagement means 113 for engaging and guiding a foundation pile received in the pile installation device. The lower section 105b is configured for guiding the pile liner 103 and thus the foundation pile 106 received in the pile liner while the pile liner is lowered into the seabed together with the foundation pile during the installation process.

[0358] The pile drilling rig 104 in the exemplary embodiment shown is an annular pile drilling rig. The pile drilling rig is combined with a driving module 114. The driving module 114 is arranged on top of an annular drilling frame supporting a plurality of drilling heads.

[0359] In the exemplary embodiment shown, the pile installation device 101 is provided with a funnel-shaped centralizer 110 for guiding the lower end pile into the pile guide.

[0360] The present invention can be summarized according to one or more of the following items:

[0361] 1. A method of piling a hollow tubular pile having a vertical centre line, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile of an offshore wind turbine) vertically into soil (e.g. into the seabed), wherein a piling system is used, the piling system comprising:

[0362] - a plurality of vibratory pile driver devices in a circular array and independently engaged on the top end of the pile column, each vibratory pile driver device being configured to apply an alternating vertical force at a corresponding vibration frequency along a working line associated with the pile driver device, the alternating vertical forces combining to produce a resultant vertical force having a resultant vertical force working line,

[0363] Therein, a plurality of vibratory pile driver devices are operated to apply their alternating out-of-phase vertical forces in such a manner that the resultant vertical force deviates from and travels about the vertical centerline of the tubular pile column.

[0364] 2. A method of piling a hollow tubular pile having a vertical centre line, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile of an offshore wind turbine) vertically into soil (e.g. into the seabed), wherein a piling system is used, the piling system comprising:

[0365] - a plurality of drop-weight pile driver devices in a circular array and independently of one another engaged on the top end of the pile, each pile driver device being configured to transfer energy from a respective drop-weight to the top end of the pile at a respective frequency along a working line associated with the pile driver device, the energy transfers of the pile driver devices combining to produce a resultant vertical force having a resultant vertical force working line, characterized in that

[0366] The plurality of drop-weight pile driver devices are operated to perform their respective out-of-phase energy transfers in such a manner that the resultant vertical force is offset from and travels about the vertical centerline of the tubular pile.

[0367] 3. A method of piling a hollow tubular pile having a vertical centre line, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile of an offshore wind turbine) vertically into soil (e.g. into the seabed), wherein a piling system is used, the piling system comprising:

[0368] - a vibrating pile driver device engaged on the top end of the pile column, the vibrating pile driver device being configured to apply an alternating force at a corresponding vibration frequency along a working line associated with the pile driver device, characterized in that

[0369] The vibratory pile driver device is constructed and operated with a horizontal working line so that a lateral vibratory force is applied to the top end of the pile.

[0370] 4. A method of piling a hollow tubular pile having a vertical centre line, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile for an offshore wind turbine) vertically into soil (e.g. into the seabed), wherein a piling system is used, the piling system comprising:

[0371] - a drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top end of the pile at a respective frequency along a vertical working line, characterized in that

[0372] At least one vibratory pile driver device distinct from the drop-weight pile driver device is engaged on the top end of the pile column, each vibratory pile driver device being constructed and operated to simultaneously with the operation of the at least one drop-weight pile driver device to apply an alternating force at a corresponding vibration frequency along a working line associated with the pile driver device.

[0373] 5. A method of piling a hollow tubular pile having a vertical centre line, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile for an offshore wind turbine) vertically into soil (e.g. into the seabed), wherein a piling system is used, the piling system comprising:

[0374] - a drop-weight pile driver device engaged on the top end of the pile, the drop-weight pile driver device being configured to transfer energy from a respective drop-weight to the top of the pile at a respective frequency along a vertical working line,

[0375] - an energy transfer assembly configured to transfer energy from a falling weight to the top end of the pile, characterized in that

[0376] The energy transfer assembly is constructed and operative to convert a portion of the energy from the falling weight into a torsional stress wave applied to the top end of the pile.

[0377] 6. A foundation pile column installation device, the foundation pile column installation device comprising:

[0378] - a support frame configured to be set up on the sea bed, the support frame preferably comprising three or more adjustable feet for adjusting the position of the support frame on the sea bed;

[0379] a pile liner for receiving the pile and for moving with the pile when the pile is lowered into the seabed, wherein the pile liner is preferably configured to form a space between the liner and the foundation pile received in the liner;

[0380] a pile drilling rig, preferably an annular pile drilling rig, arranged at the lower end of the pile liner for drilling pile holes capable of receiving the liner and the foundation piles received in the liner; and

[0381] - A pile guide, which is retained in the supporting frame and is used to guide the pile and / or pile liner (in which the foundation pile is accommodated) during the pile installation process, ie when the pile and pile liner are lowered into the seabed.

[0382] 7. A foundation installation device according to the preceding clause, wherein the pile guide comprises an upper section and a lower section, the upper section being provided with one or more pile engagement devices for engaging and guiding a foundation pile housed in the pile installation device, the lower section being configured for guiding the pile liner as it is lowered into the seabed together with the foundation piles during the installation process, and thereby guiding the foundation piles housed in the pile liner.

[0383] 8. A method for installing a wind turbine foundation pile, preferably using a pile installation device according to the preceding clause, wherein the method comprises the following steps:

[0384] placing the pile mounting device on the seabed;

[0385] lowering a foundation pile into a pile guide of the installation device and into a pile liner received in the pile guide;

[0386] Drilling a pile hole at the lower end of the pile liner and the foundation pile accommodated in the pile liner, and lowering the pile drilling machine, the pile liner and the foundation pile into the pile hole;

[0387] removing the pile liner and the pile drill from the pile hole and optionally cementing the space created by removing the pile liner and the pile drill; and

[0388] Remove the stake mounting device.

[0389] 9. A piling system for driving a hollow tubular pile having a vertical centerline, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile for an offshore wind turbine) vertically into soil (e.g. into the seabed), wherein the piling system is used, the piling system comprising:

[0390] an impact hammer for generating an axial pile driving force along a pile driving axis, wherein the pile driving axis is aligned with a vertical centerline of the pile, to drive the pile into the seabed;

[0391] a vibration drive for generating an alternating force about the pile driving axis at a vibration frequency to vibrate the pile about a vertical centerline and reduce friction between the pile and the seabed; and

[0392] a floating support which connects the vibration drive to the impact hammer or is configured to connect the vibration drive to the pile,

[0393] The floating support is configured to allow the vibration drive to move freely along the piling axis to prevent the impact force from being directly transmitted from the impact hammer to the vibration drive, and to limit, preferably prevent, the vibration drive from moving freely around the piling axis to enable the torsional force to be directly transmitted from the torsional drive to the impact hammer or the pile.

[0394] 10. A piling system according to clause 9, wherein the floating support enables the vibration drive to move relative to the hammer along the piling axis within a range of at least 20 cm, preferably at least 40 cm, for example 60 cm or more.

[0395] 11. A piling system according to item 9 or item 10, wherein the floating support is configured to cushion the impact force when the impact force is transmitted from the impact hammer to the vibration driver, for example, the floating support is provided with one or more elastic bodies, such as one or more springs or cylinders, between the impact hammer and the vibration driver.

[0396] 12. Piling system according to one or more of clauses 9 to 11, wherein the floating support is provided with damping means which reduce the relative movement of the vibratory drive when one or both limits of the relative movement achieved by the floating support are reached.

[0397] 13. Piling system according to item 12, wherein the buffer device has a working path of several decimeters, i.e. a path in which the relative speed of the vibration drive is reduced, for example a working path of at least 20 cm, preferably a working path of more than 30 cm, for example a working path of at least 40 cm.

[0398] 14. A piling system according to clause 12 or clause 13, wherein the buffer device comprises one or more hydraulic cylinders coupled to a gas buffer, and wherein the hydraulic cylinders preferably have a working trajectory of 30 cm.

[0399] 15. A piling system according to one or more of clauses 9 to 14, wherein the torsional drive comprises a plurality of vibrating pile driver devices arranged in a circular array around the piling axis, wherein each vibrating pile driver is configured to apply an alternating force at a vibration frequency in a plane perpendicular to the vertical centerline of the pile column to cause the pile column to vibrate about the vertical centerline.

[0400] 16. A piling system according to one or more of clauses 9 to 15, wherein the impact hammer generates the impact force at a piling frequency, and wherein the vibration drive generates the torsional force at a torsional frequency, and wherein the torsional frequency is at least five times, preferably at least ten times, for example at least twenty times, the piling frequency.

[0401] 17. A piling system according to one or more of clauses 9 to 16, wherein the floating support comprises an annular frame configured to extend around a piling axis in a working state, and wherein a vibratory drive, such as a plurality of vibratory pile driver devices, is mounted to the annular frame.

[0402] 18. A piling system according to one or more of items 9 to 17, wherein the floating support comprises a plurality of support arms, each arm having a base end and a support end, wherein the support arms are provided with a pivot axis at their base ends and support a vibrating drive at their support ends, preferably each support arm supports a vibrating pile driver device at the support end of the support arm.

[0403] 19. A piling system according to clause 18, wherein the pivot axis of each support arm extends in a plane perpendicular to the piling axis.

[0404] 20. A piling system according to clause 18 or clause 19, wherein the pivot axis of each support arm extends in a plane parallel to the piling axis.

[0405] 21. Piling system according to one or more of items 18 to 20, wherein the pivot axis of each support arm extends in a radial direction relative to the piling axis.

[0406] 22. Piling system according to one or more of items 9 to 21, wherein the pivot axis of each support arm extends perpendicularly to the longitudinal axis of the support arm.

[0407] 23. A piling system according to one or more of items 18 to 22, wherein the floating support comprises a plurality of flexible support arms, each flexible support arm having a base end and a support end, wherein the flexible support arms support a vibration drive at their support ends, preferably each flexible support arm supports a vibration pile driver device at the support end of the flexible support arm.

[0408] 24. A piling system according to one or more of clauses 18 to 23, wherein the support arm is tangent to a circle centred on the piling axis when seen in top view.

[0409] 25. A piling system according to clause 18 or clause 23, wherein the support arms extend in a radial direction relative to the piling axis when seen in a top view.

[0410] 26. A piling system according to one or more of items 9 to 17, wherein the floating support comprises a plurality of linkage systems, each linkage system having a base linkage and a support linkage, wherein the linkage systems support the vibration drive by means of their support linkages, preferably each linkage system supports the vibration drive by means of the support linkage, preferably such that the vibration drive can move in a direction parallel to the piling axis.

[0411] 27. Piling system according to one or more of clauses 9 to 26, wherein the floating support comprises a plurality of fins and slots extending parallel to the piling axis, such that the vibratory drive is movable in a direction parallel to the piling axis.

[0412] 28. A piling system according to one or more of items 9 to 27, wherein the floating support comprises one or more elastic bodies, such as springs or cylinders, for elastically supporting the vibration driver in a direction parallel to the piling axis, and wherein the elastic body is preferably configured to cushion the impact force when the impact force is transmitted from the impact hammer to the vibration driver.

[0413] 29. A piling system according to one or more of clauses 9 to 28, wherein the impact hammer is a gravity hammer, such as a drop weight hammer.

[0414] 30. Piling system according to one or more of clauses 9 to 29, wherein the impact hammer is a forced impact hammer, preferably a hydraulic forced impact hammer.

[0415] 31. A piling system according to one or more of clauses 9 to 30, wherein the hammer is a combination of a plurality of hammers, wherein each of the hammers is configured to transfer energy to the pile at a certain frequency, and wherein the hammers are configured to operate sequentially.

[0416] 32. The piling system according to one or more of clauses 9 to 31, wherein the pile driver comprises an anvil configured to couple with a top end of the foundation pile column to transmit the axial piling force from the pile driver to the foundation pile column.

[0417] 33. A piling system according to clause 32, wherein the floating support is mounted to the anvil.

[0418] 34. A piling system according to one or more of items 9 to 32, wherein the floating support is mounted to the top end of a monolithic pile (eg comprising a ring mounted on the top end of the pile).

[0419] 35. A piling system according to one or more of items 9 to 34, wherein the monolithic pile is configured to be engaged by a floating support, for example, radially extending teeth are provided for cooperating with driving teeth of the floating support, and / or a seat is provided at the top end of the monolithic pile for accommodating the floating support.

[0420] 36. A piling system according to one or more of items 9 to 35, wherein the floating support enables the vibration drive to be moved relative to the hammer along the piling axis within a range of at least 20 cm, preferably at least 40 cm, for example 60 cm or more.

[0421] 37. A vessel, such as a jack-up vessel, provided with a piling system according to one or more of items 9 to 36.

[0422] 38. A method of piling a hollow tubular pile having a vertical centre line, a top end and an open foot end (e.g. a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile for an offshore wind turbine) vertically into soil (e.g. into the seabed), using a piling system, preferably a piling system according to one or more of the preceding clauses, wherein the method comprises the following steps:

[0423] - setting up the pile with the open foot in the seabed while supporting the pile above the horizontal plane in a radial direction using pile guides mounted on a vessel, such as a jack-up vessel;

[0424] - using an impact hammer to generate an axial piling force along a piling axis to drive the pile into the seabed, wherein the piling axis is aligned with the vertical centerline of the pile;

[0425] - using a vibratory drive to generate a torsional force about the pile driving axis to rotate the pile about a vertical centerline, thereby reducing friction between the pile and the seabed; and

[0426] - free movement of the vibrating drive along the piling axis to prevent direct transmission of impact forces from the hammer to the vibrating drive, and restrict, preferably prevent, free movement of the vibrating drive around the piling axis to enable direct transmission of torsional forces from the torsional drive to the hammer or the pile.

Claims

1. A piling system for driving a hollow tubular pile having a central longitudinal axis, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 meters at the open foot end, such as a monolithic pile for an offshore wind turbine, vertically into soil, such as into the seabed, wherein: The piling system comprises: - at least one hammer device configured to transfer energy from the respective hammer device to the top of the pile at a respective frequency along a piling axis, wherein the piling axis is parallel to, and preferably coincides with, a central longitudinal axis of the pile; and - a torsional vibration drive, wherein the torsional vibration drive comprises at least one vibrating pile driver device engaged on a pile column or on a hammer device, and wherein each vibrating pile driver device of the torsional vibration drive is constructed and operated to apply an alternating force at a corresponding vibration frequency about a pile driving axis simultaneously with the operation of at least one hammer device.

2. The piling system according to claim 1, wherein: The floating support connects the torsional vibration drive to the hammer device, or connects the torsional vibration drive to the pile, wherein the floating support is configured to allow free movement of the torsional vibration drive along the piling axis to prevent energy from being directly transferred from the hammer device to the torsional vibration drive, and to restrict, preferably prevent, free movement of the torsional vibration drive around the piling axis to enable torsional forces to be directly transferred from the torsional vibration drive to the hammer device or the pile.

3. The piling system according to claim 1 or 2, wherein: The piling system comprises a plurality of hammer devices arranged to apply vertical forces along working lines associated with respective hammer devices, and wherein the vertical forces combine to produce a resultant vertical force having a resultant vertical force working line, and wherein the vertical force working line is parallel to the piling axis, preferably coincident with the piling axis.

4. Piling system according to one or more of the preceding claims, wherein: At least one hammer device is a vibratory hammer device preferably engaged on the top end of the pile column and configured to transfer energy from the respective vibratory hammer device to the top of the pile column at a respective frequency along the piling axis.

5. A piling system according to one or more of claims 1 to 3, wherein: At least one hammer device is a drop-weight pile driver device engaged on a top end of the pile column and configured to transfer energy from a respective drop-weight to the top of the pile column at a respective frequency along the pile driving axis.

6. Piling system according to one or more of the preceding claims, wherein: The torsional vibration drive comprises a plurality of vibrating pile driver devices arranged, for example, in a circular array around a piling axis, and wherein each vibrating pile driver device is configured to apply an alternating force at a vibration frequency in a plane perpendicular to the piling axis to vibrate the pile column around the piling axis.

7. Piling system according to one or more of the preceding claims, wherein: The torsional vibration driver is distinct from a hammer device and is configured to engage the pile, for example, at a larger diameter lower pile section below a smaller diameter pile top section of the pile.

8. Piling system according to one or more of the preceding claims, wherein: The floating support enables the torsional vibration driver to move along the vertical working line relative to a hammer device, such as an impact hammer device, within a range of at least 20 cm, preferably within a range of at least 40 cm, such as 60 cm or more.

9. Piling system according to one or more of the preceding claims, wherein: The floating support is configured to cushion the impact force generated by at least one hammer device when it is transmitted from the hammer device to the torsional vibration driver. For example, the floating support is provided with one or more elastic bodies, such as one or more springs or cylinders, between the impact hammer or pile and the torsional vibration driver.

10. Piling system according to one or more of the preceding claims, wherein: The torsional vibration drive is configured to apply a torsional vibration load with a frequency of at least 50 Hz, preferably at least 65 Hz, for example 80 Hz.

11. Piling system according to one or more of the preceding claims, wherein: At least one hammer device is a vibratory hammer device and is configured to apply a vibratory load along the piling axis having a frequency of at least 14 Hz, preferably at least 17 Hz, for example 20 Hz.

12. Piling system according to one or more of the preceding claims, wherein: The hammer device is configured to generate impact forces at a pile driving frequency, and wherein the torsional vibration drive generates torsional forces at a torsional frequency, and wherein the torsional frequency is at least three times, preferably at least four times, such as at least five times, the pile driving frequency.

13. A piling system according to one or more of claims 9 to 11, wherein: The floating support is provided with a damping device which damps a movement of the torsional vibration driver along the piling axis and relative to the hammer device, wherein the movement is caused by the hammer device.

14. The piling system according to claim 13, wherein: The damping device has an operating path of several decimeters, ie a path in which the relative speed of the torsional vibration drive is reduced, for example an operating path of at least 20 cm, preferably more than 30 cm, for example at least 40 cm.

15. A piling system according to claim 13 or 14, wherein: The buffer device comprises one or more hydraulic cylinders coupled to a gas buffer, and wherein the hydraulic cylinders preferably have a working trajectory of 30 cm.

16. Piling system according to one or more of the preceding claims, wherein: The piling system comprises an anvil configured to couple with a top end of a foundation pile column to transmit an axial piling force from a pile driver to the foundation pile column, and preferably wherein a floating support is mounted to the anvil.

17. Piling system according to one or more of the preceding claims, wherein: The piling system comprises a sleeve for receiving a top end of a pile, wherein the sleeve is configured to be fixed to the pile against rotation about a longitudinal axis of the pile, and preferably wherein the floating support is mounted to the sleeve.

18. Piling system according to one or more of the preceding claims, wherein: The floating support is mounted to the top end of a monolithic pile, which for example comprises a ring mounted on the top end of the pile.

19. A vessel, such as a jack-up vessel, provided with a piling system according to one or more of the preceding claims.

20. A method of piling for vertically driving a hollow tubular pile having a vertical centre line, a top end and an open foot end, such as a larger diameter pile having an outer diameter of at least 5 metres at the open foot end, such as a monolithic pile for an offshore wind turbine, into soil, such as a seabed, wherein: Use of a piling system, preferably a piling system according to one or more of the preceding claims, wherein the piling method comprises the following steps: - setting up the pile with the open foot in the seabed while supporting the pile above the horizontal plane in a radial direction using pile guides mounted on a vessel, such as a jack-up vessel; - using at least one hammer device to generate an axial piling force along a piling axis to drive the pile into the seabed, wherein the piling axis is aligned with a vertical centerline of the pile; - using a torsional vibration drive to generate a torsional force about the pile driving axis to rotate the pile about a vertical centerline, thereby reducing friction between the pile and the seabed; and - allowing the torsional vibration drive to move freely along the piling axis to prevent the impact force from being directly transmitted from the impact hammer to the torsional vibration drive, and restricting, preferably preventing, the torsional vibration drive from moving freely around the piling axis to enable the torsional force to be directly transmitted from the torsional vibration drive to the impact hammer or the pile.

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