NL2035355B1

NL2035355B1 - Vibrator assembly

Info

Publication number: NL2035355B1
Application number: NL2035355A
Authority: NL
Inventors: Casper Jung Boudewijn
Original assignee: Iqip Holding Bv
Priority date: 2023-07-12
Filing date: 2023-07-12
Publication date: 2025-01-27
Also published as: WO2025014355A1

Abstract

A vibrator assembly for installing a pile into the ground is disclosed. The vibrator assembly comprises connection means configured to engage a pile, wherein the connection means comprises at least one connection member; a first vibrator, the first vibrator comprising a first actuator coupled to a first mass, the first actuator being configured, when actuated, to vibrate the first mass along a first linear path that is tangential to, or is parallel to a tangent of, a surface of the pile; and a second vibrator, the second vibrator comprising a second actuator coupled to a second mass, the second actuator being configured, when actuated, to vibrate the second mass along a second linear path that is tangential to, or is parallel to a tangent of, the surface of the 10 pile. [Fig. 1]

Description

VIBRATOR ASSEMBLY

This invention relates generally to a vibrator assembly for installing piles into the ground. More specifically, although not exclusively, this invention relates to a vibrator assembly for installing offshore foundation piles.

Offshore piles, for example foundation piles such as monopiles or jacket piles, are driven into soil to provide foundations for above-water structures.

The piles are usually driven into the floor using an axial force. The axial force may be in the form of sequential axial impulses, or pulses, provided by a pile driving tool, for example a pile driving hammer. The axial force may be in the form of a vibratory axial force applied to the pile. Clearly, driving in the pile using axial force requires sufficient energy to be transmitted to the pile to overcome the resistance offered by the soil. The resistance includes the direct force acting on the toe, or lower edge, of the pile, as well as friction forces acting on the radially inner and outer surfaces of the pile.

In order to overcome the direct force acting on the toe, the pile must displace the floor material away from the path of the toe as the pile is driven into the soil. The diameter of the pile may be, for example, between 8 m and 13 m, and the wall thickness may be, for example, 100 mm.

Therefore, the surface area of the toe may be up to, for example, 4 m2. As such, to move the pile 250 mm into the soil, up to 1 m3 of soil might need to be displaced which requires a large amount of energy. Furthermore, as the pile moves deeper, the soil is more densely packed and so the resistance offered by the soil to the toe increases, requiring an increasing amount of energy to be imparted to the pile.

It will be appreciated that the friction forces acting on the radial faces of the pile also increase with depth, as more of the surfaces become in contact with soil. Furthermore, as the pile penetrates deeper into the soil the direct forces acting on the radial faces increases due to the more densely packed soil, thereby increasing the friction forces.

Overcoming these resistances typically requires very large axial forces to be applied to the piles.

These axial forces create large stress fluctuations in the piles which sometimes cause damage, or even failure, in the piles or associated structures. The damage may be fatigue damage, which affects the remaining fatigue capacity of the pile, which, in turn, affects the lifetime of the pile and associated structures. Accordingly, the piles must be designed with sufficient strength to withstand the high impact forces, which increases the cost of the piles. For example, it may be the load required to drive the pile that governs the wall thickness of the pile. Furthermore, the vibration of the pile caused by the impacts delivered with an installation tool result in large amounts of noise during the piling process, which has negative environmental effects, and also increases health risks to nearby personnel.

It is known to vibrate the pile to reduce the resistance offered by the soil. In this manner, the requirement for an applied axial force is reduced, or in some cases completely removed with the pile instead ‘sinking’ through the soil as the pile is vibrated. However, known systems utilise rotating masses to vibrate the pile — for example the systems disclosed in WO2021040523A1 and

US3383531 — leading to additional complexity.

It is an objective of the present invention to overcome at least some of these limitations.

According to a first aspect of the invention there is provided a vibrator assembly for installing a pile into the ground, the vibrator assembly comprising: connection means configured to engage a pile, wherein the connection means comprises at least one connection member; a first vibrator, the first vibrator comprising a first actuator coupled to a first mass, the first actuator being configured, when actuated, to vibrate the first mass along a first linear path that is tangential to, or is parallel to a tangent of, a surface of the pile; and a second vibrator, the second vibrator comprising a second actuator coupled to a second mass, the second actuator being configured, when actuated, to vibrate the second mass along a second linear path that is tangential to, or is parallel to a tangent of, the surface of the pile, wherein the first vibrator and the second vibrator are coupled to the connection means such that forces generated by vibration of the first mass and the second mass are transferred to the pile by the connection means.

With the claimed arrangement, the reaction forces from the vibrations of the first and second masses are transferred to the pile via the connection members. This causes the pile to vibrate within the XY plane, where the longitudinal axis of the pile extends in the Z-direction. As the linear vibrations act tangentially to the outer surface of the pile, these result in the transfer of torsional vibrations to the pile. That is, the pile is caused to vibrate about its longitudinal axis. The vibrations of the pile act to at least partially fluidise the soil beneath/around the pile, reducing the soil resistance such that the pile can ‘sink’ into the ground. As such, the energy required to install the pile to a predetermined depth is greatly reduced and there is no requirement for an impact hammer, resulting in a much quieter installation. The use of linear vibrators is more simple than known solutions, for example solutions using rotating masses. In addition, the penetration of the pile can be achieved in the same manner or even in a more controlled manner than achieved with rotating masses. That is, the use of linear actuators provides increased sensitivity between the vibrations of the masses and the resulting vibration of the pile. This allows greater control over the installation of the pile.

In certain embodiments, the at least one connection member comprises: a first connection member positioned so as to engage the surface of the pile at a first circumferential position; and a second connection member positioned so as to engage the surface of the pile at a second circumferential position.

In certain embodiments, the first vibrator is positioned so as to be circumferentially aligned with a first circumferential position of the surface of the pile, wherein the first linear path is tangential to, or is parallel to a tangent of, the surface of the pile at the first circumferential position, and the second vibrator is positioned so as to be circumferentially aligned with a second circumferential position of the surface of the pile, wherein the second linear path is tangential to, or is parallel to a tangent of, the surface of the pile at the second circumferential position.

In certain embodiments, the first linear path is substantially parallel to the second linear path.

In certain embodiments, the first vibrator is positioned so as to be circumferentially aligned with the first connection member, wherein the first linear path is tangential to, or is parallel to a tangent of, the surface of the pile at the first circumferential position, and the second vibrator is positioned so as to be circumferentially aligned with the second connection member, wherein the second linear path is tangential to, or is parallel to a tangent of, the surface of the pile at the second circumferential position.

In certain embodiments, the first circumferential position is diametrically opposed to the second circumferential position.

In certain embodiments, the first actuator is configured to vibrate the first mass along the first linear path at a frequency of from about 40 to about 80 Hz, wherein the second actuator is configured to vibrate the second mass along the second linear path at a frequency of from about 40 to about 80 Hz.

In certain embodiments, the vibrator assembly comprises a control system in communication with the first actuator and the second actuator, wherein the control system is configured to actuate the first actuator and the second actuator.

In certain embodiments, the control system is configured to actuate the first actuator and the second actuator according to a vibration pattern, wherein the vibration pattern is configured such that the during simultaneous vibrations of the first mass and the second mass, the first mass moves along the first linear path in a direction that corresponds to a circumferential direction around the surface of the pile and the second mass moves along the second linear path in a direction that corresponds to the circumferential direction around the surface of the pile.

In certain embodiments, the control system comprises a memory storing the vibration pattern.

In certain embodiments, the vibrator assembly comprises at least one pressure sensor configured to monitor forces applied to the pile by the vibrators.

In certain embodiments, the vibrator assembly further comprises at least one axial vibrator, each axial vibrator of the at least one axial vibrator comprising an actuator coupled to a mass, the actuator being configured, when actuated, to vibrate the mass along a path that is parallel to, or coaxial with, the longitudinal axis of the pile.

In certain embodiments, the actuator of the axial vibrator is configured to vibrate the mass along the path at a frequency of from about 25 Hz to about 40 Hz.

In certain embodiments, the vibrator assembly comprises a connection point for connection to a lifting device.

In certain embodiments, the at least one connection member is a hydraulic clamp.

According to a second aspect of the invention there is provided a system for installing a pile into the ground, the system comprising: the vibrator assembly of the first aspect of the invention; and a support structure for supporting the pile in a predetermined orientation at an installation position.

In certain embodiments, the system further comprises a sensor configured to determine the relative position between the pile and the support structure during installation.

According to a third aspect of the invention there is provided a kit of parts comprising: the vibrator assembly of any embodiment of the first aspect of the invention; and a pile. 5

In certain embodiments, the pile is a monopile or a jacket pile.

According to a fourth aspect of the invention there is provided a method for installing a pile into the ground, the method comprising: positioning a pile at an installation position; engaging the pile with connection means of a vibrator assembly wherein the connection means comprises at least one connection member; actuating a first actuator of a first vibrator to vibrate a first mass along a first linear path that is tangential to, or is parallel to a tangent of, a surface of the pile; and actuating a second actuator of a second vibrator to vibrate a second mass along a second linear path that is tangential to, or is parallel to a tangent of, the surface of the pile; wherein the first vibrator and the second vibrator are coupled to the connection means such that forces generated by vibration of the first mass and the second mass are transferred to the pile by the connection means.

In certain embodiments, the vibrator assembly is that of any embodiment of the first aspect of the invention.

In certain embodiments, engaging the pile with connection means comprises: engaging the surface of the pile at a first circumferential position with a first connection member of the at least one connection member; and engaging the surface of the pile at a second circumferential position with a second connection member of the at least one connection member.

In certain embodiments, the pile is a monopile or a jacket pile.

In certain embodiments, the installation position is offshore.

In certain embodiments, once the pile is installed into the ground to a predetermined depth, the pile is configured to support an above-surface structure, for example a wind turbine.

In certain embodiments, the method further comprises actuating an actuator of an axial vibrator to vibrate a mass along a path that is parallel to, or coaxial with, the longitudinal axis of the pile.

According to another aspect of the present invention there is provided computer readable instructions which, when executed by a computer, are arranged to perform a method according to the fourth aspect of the invention.

According to another aspect of the present invention there is provided a non-transitory, computer- readable storage medium storing instructions thereon that, when executed by one or more electronic processors, causes the one or more electronic processors to carry out a method according to the fourth aspect of the invention.

As used herein the position of features of the vibrator assembly may be described with respect to the pile, representing the ‘in-use’ configuration of the vibrator assembly. The position of features of the vibrator assembly may equally be defined with respect to a plane and an axis normal to the plane, where the plane corresponds to an upper surface of a pile and the axis corresponds to a longitudinal axis of the pile. For example, the circumferential positions of the connection members and the first and second linear paths may be defined with respect to a circle extending around the axis within the plane. The circle may correspond to an outer and inner curved surface of the pile.

The vibrator assembly will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 shows an exploded view of a vibrator assembly (shown in side cross-section) and a pile {shown in perspective view);

Figure 2 shows a side cross-section of the vibrator assembly and pile shown in Figure 1;

Figure 3 shows a top cross-section of the vibrator assembly and pile shown in Figure 1;

Figure 4 shows a side cross-section of another vibrator assembly;

Figure 5 shows a side cross-section of another vibrator assembly; and

Figure 6 shows a top view of another vibrator assembly.

Turning to Figure 1, there is shown a vibrator assembly 100 for installing a pile 200 into the ground.

In this example the pile 200 is a monopile, but it will be appreciated that the vibrator assembly 100 disclosed herein may be used for the installation of other piles, such as jacket piles. The pile 200 is illustrated schematically as a continuous cylindrical pile having an annular cross-section but it would be understood that the pile 200 may have any suitable shape or structure. For example the pile 200 may be constructed from one or more cylindrical sections each of differing diameters. An upper section of the pile 200 may be frustoconical in shape.

In the illustrated example, the vibrator assembly 100 is used in an offshore application. That is, 5s the vibrator assembly 100 is used to install the pile 200 into the soil of an underwater floor, the water surface being labelled 300. Once the pile 200 is installed into the ground to a predetermined depth, the pile is configured to support an above-surface structure, for example a wind turbine.

The soil may be of any known sail type which is suitable for pile driving or pile installation, such as clay or sand. It would be understood that the vibrator assembly 100 may be equally applicable to onshore applications.

The vibrator assembly 100 includes connection means configured to engage the pile 200. In this example, the connection means includes a first connection member 102 positioned so as to engage a surface of the pile at a first circumferential position. The connection means further includes a second connection member 104 positioned so as to engage the surface of the pile at a second circumferential position.

Any suitable connection member may be used, provided they are configured to transfer vibrations from the vibrators to the pile 200 as described below. In this example, the first connection member 102 and the second connection member 104 are hydraulic clamps. The hydraulic clamps may be of the type disclosed in US6302222B1. The connection members may include at least one sensor to monitor pre-tension prior to an installation operation.

Each hydraulic clamp may be configured to engage with the outer curved surface of the pile 200, the inner curved surface of the pile 200, or both, so as to fix the position of the vibrator assembly 100 with respect to the pile 200. It would be understood that for a flanged pile the first connection member 102 and the second connection member 104 may engage with upper and lower surfaces of the flange so as to fix the position of the vibrator assembly 100 with respect to the pile. As used herein ‘the surface’ with which each connection member 102, 104 engages could be any of the aforementioned surfaces depending on the type of connection member 102, 104 used and the structure of the pile 200. From herein, as an example, reference will be made to the outer surface 202 of the pile 200 as ‘the surface’.

The vibrator assembly 100 includes a first vibrator including a first actuator 106 coupled to a first mass 110. The first actuator 106 is configured, when actuated, to vibrate the first mass 110. The vibrator assembly 100 also includes a second vibrator including a second actuator 108 coupled to a second mass 112. The second actuator 108 is configured, when actuated, to vibrate the second mass 112.

The actuators 106, 108 may be any type of actuator or shaker suitable for vibrating the masses 5s 110, 112 at the required frequency. For example the actuators 106, 108 may each comprise a linear actuator, or a rotor or motor coupled to the respective mass 110, 112 by means of a rack and pinion arrangement or the like.

The first vibrator and the second vibrator are coupled to the connection means such that forces generated by vibration of the first mass 110 and the second mass 112 are transferred to the pile 200 by the connection means. For example, the actuator 108, 108 of each of the first and second vibrators may be connected to the connection means to allow transfer of force therebetween.

In the illustrated examples, the first actuator 106, the second actuator 108, the first mass 110 and the second mass 112 are housed within a housing 122, with the first connection member 102 and the second connection member 104 extending from and/or are coupled to the housing 122. In this manner, as the actuators 106, 108 vibrate the masses 110, 112, the reaction force applied by the vibrating masses 110, 112 to the actuators 108, 108 is transferred via the housing 122 to the connection members 102, 104. In other examples, such as the example of Figure 6, the actuators 106, 108 and connection members 102, 104 may each be mounted on a plate, frame or collar.

The first actuator 106 is configured, when actuated, to vibrate the first mass 110 along a first linear path 124 that is tangential to, or is parallel to a tangent of, the outer surface 202 of the pile 200. In the same manner to the first actuator 106, the second actuator 108 is configured, when actuated, to vibrate the second mass 112 along a second linear path 126 that is tangential to, or is parallel to a tangent of, the outer surface 202 of the pile 200.

In this example the first vibrator is positioned so as to be circumferentially aligned with a first circumferential position of the outer surface 202 of the pile 200, with the first linear path 124 being tangential to, or parallel to a tangent of, the outer surface 202 of the pile 200 at the first circumferential position. Similarly, the second vibrator is positioned so as to be circumferentially aligned with a second circumferential position of the outer surface 202 of the pile 200, with the second linear path 126 being tangential to, or parallel to a tangent of, the outer surface 202 of the pile 200 at the second circumferential position. As used herein ‘circumferential alignment’ refers to an alignment along a radius of the pile 200.

It would be understood that the relative radial positioning between each mass 110, 112 and the pile 200 will dictate whether the corresponding linear path is tangential to the outer surface 202 of the pile 200 or is parallel to a tangent of the outer surface 202 of the pile 200. As best shown in Figure 3, the first mass 110 {as an example) is radially spaced from the annular profile of the pile 200 such that the first linear path 124 is parallel to a tangent of the outer surface 202 of the pile 200. In other examples the first mass 110 may be positioned directly above the pile 200 such that the first linear path 124 is substantially tangential to the outer surface 202 of the pile 200.

A pile installation or pile driving operation involving the vibrator assembly 100 includes positioning the pile 200 at an installation position; engaging the outer surface 202 of the pile 200 at a first circumferential position with the first connection member 102 and engaging the outer surface 202 of the pile 200 at a second circumferential position with the second connection member 104. The first actuator 106 is then actuated to vibrate the first mass 110 along the first linear path 124 and the second actuator 108 is actuated to vibrate the second mass 112 along the second linear path 126.

The reaction forces from the vibrations of the first and second masses 110, 112 are transferred to the pile 200 via the connection members 102, 104. This causes the pile 200 to vibrate within the XY plane, following the coordinate system labelled in Figure 1, where the longitudinal axis of the pile 200 extends in the Z-direction. As the linear vibrations act tangentially to the outer surface 202 of the pile 200, these result in the transfer of torsional vibrations to the pile 200. That is, the pile 200 is caused to vibrate about its longitudinal axis.

The vibrations of the pile 200 act to at least partially fluidise the soil beneath/around the pile 200, reducing the soil resistance such that the pile 200 can ‘sink’ into the ground. As such, the energy required to install the pile 200 to a predetermined depth is greatly reduced and there is no requirement for an impact hammer, resulting in a much quieter installation. The use of linear vibrators is more simple than known solutions, for example solutions using rotating masses. In addition, the penetration of the pile 200 can be achieved in the same manner or even in a more controlled manner than achieved with rotating masses. That is, the use of linear actuators provides increased sensitivity between the vibrations of the masses and the resulting vibration of the pile 200. This allows greater control over the installation of the pile 200.

Any suitable structure and/or material may be used for the masses, for example a solid block of material. The masses 110, 112 may, for example, each have a mass of from about 0.2 tonnes to about 1 tonne, aptly from about 0.5 tonnes to about 0.9 tonnes. It would be appreciated that the required mass for each mass 110, 112 would depend on the installation capacity of the vibrator assembly 100 and the number of vibrators in the assembly 100.

In this example the actuators 106, 108 are configured to vibrate the masses 104, 106 along their respective linear paths at a frequency of from about 40 to about 80 Hz. It has been found that vibrations at such frequencies help ensure the pile 200 is vibrated enough to reduce the soil resistance but the system still remains stable during vibrations of the pile 200.

In this example the vibrator assembly 100 includes a control system 120 in communication with thefirst actuator 106 and the second actuator 108.

The control system 120 may include one more of a controller, processing means and a memory.

The processing means may be one or more electronic processing devices which operably execute computer-readable instructions. The memory may be one or more memory devices. The memory may be electrically coupled to the processing means. The memory may be configured to store instructions. For example, the processing means may be configured to access the memory and execute the instructions stored thereon. The controller may comprise an input means and an output means. The input means may comprise an electrical input of the controller. The output means may comprise an electrical output of the controller. The input is arranged to receive an input signal, for example from a user, or a signal from a sensor, for example. The output is arranged to output actuation instructions to the vibrators of the vibrator assembly 100 as described herein.

The control system 120 may communicate wirelessly with the first and second actuators 108, 108. Alternatively a wired connection may be present between the control system 120 and the first and second actuators 106, 108. The control system 120 may be positioned within the housing 122 or located remotely from the other components of the vibrator assembly 100.

The control system 120 is configured to actuate the first actuator 106 and the second actuator 108. In this example the control system 120 is configured to actuate the first actuator 106 and the second actuator 108 according to a vibration pattern. The vibration pattern may be stored within the memory of the control system 120.

The vibration pattern is configured such that the during simultaneous vibrations of the first mass 110 and the second mass 112, the first mass 110 moves along the first linear path 124 in a direction that corresponds to a circumferential direction around the outer surface 202 of the pile 200 and the second mass 112 moves along the second linear path 126 in a direction that corresponds to the circumferential direction around the outer surface 202 of the pile 200. That is, the directions followed by each mass 110, 112 along their respective linear paths 124, 126 during simultaneous vibrations correspond to the same clockwise or anti-clockwise direction. As such, the vibrations of the masses 110, 112 cooperate to generate a moment about the longitudinal axis of the pile 200. These rotational or torsional pile vibrations reduce the soil resistance in the manner described above.

Figures 4 and 5 illustrate embodiments of the vibrator assembly 100, in which the vibrator assembly 100 further includes an axial vibrator including an actuator 114 coupled to a mass 116.

The actuator 114 is configured, when actuated, to vibrate the mass 116 along a path 128 that is parallel to, or coaxial with, the longitudinal axis of the pile. In the examples of Figures 4 and 5, at least the actuator 114 is housed within the housing 122. It would be understood that in examples including a plate or collar the actuator 114 may also be mounted on the plate or collar so as to transfer reaction forces from vibrating the mass 116 to the pile 200. The vertical reaction forces from vibrating the mass 116 help drive, or gently force, the pile 200 through the, at least partly, fluidised soil, always depending on the amount of water in the soil and/or the compactness of the soil below the pile toe, taking advantage of the reduced soil resistance. In this manner the gentle vertical vibrations can replace impacts from hammers or vibro-hammers such that the energy input and noise is reduced.

The mass 116 may, for example, be from about 1 tonne to about 15 tonnes, aptly from about 2 tonnes to about 10 tonnes, aptly from about 2 tonnes to about 6 tonnes. It would be appreciated that the required mass of each mass 116 would depend on the installation capacity of the vibrator assembly 100 and the number of vertical vibrators in the assembly 100. The actuator 114 may vibrate the mass 116 along the axial path at a frequency of from about 25 to about 40 Hz, for example.

The vibrator assembly 100 may include at least one pressure sensor configured to monitor the forces applied to the pile 200 by the axial vibrators.

During pile installation the pile 200 may be supported in a predetermined orientation at the installation position by a support structure, for example an outrigger frame or pile gripper mounted on a floating installation vessel. The installation system may include a sensor configured to determine the relative position between the pile 200 and the support structure during installation.

In this manner, the installation progress can be monitored and the vibration settings can be tailored accordingly.

Various modifications to the above described embodiments are possible. For example, although the vibrator assembly 100 illustrated in Figures 1 to 5 includes two vibrators, the vibrator assembly 100 may include any number of vibrators (otherwise termed torsional vibrators due to the resulting torsional effect on the pile 200), for example three, four or more. Figure 6 shows an example where the vibrator assembly 100 includes four vibrators arranged around, and mounted to, an annular plate or collar member 400. In some embodiments it is preferable to use a larger number of vibrators, such that the mass used for each vibrator can be smaller and therefore easier to move. Aptly, there are from four to sixteen vibrators. Similarly, the vibrator assembly 100 may include any number of axial vibrators and/or connection members, for example one, three or more.

As mentioned above, the mass of the masses of each vibrator (both torsional and axial) may vary depending on the number of vibrators and the required installation capacity of the vibrator assembly 100. For example, the mass of the masses may be lower in an assembly 100 with a greater number of vibrators. As the total mass of the vibrators (i.e. the dynamic mass of the vibrator assembly 100) moves together with the pile it costs energy. As such, it is preferable to keep the total dynamic mass as low as possible, for example less than 10% of the mass of the pile 200 to be installed.

In a first non-limiting specific example, the vibrator assembly 100 includes: e Four torsional vibrators, each torsional vibrator having a mass of about 0.9 tonnes; and e Four axial vibrators, each axial vibrator having a mass of about 2.3 tonnes.

In a second non-limiting specific example, the vibrator assembly 100 includes: e Sixteen torsional vibrators, each torsional vibrator having a mass of about 0.7 tonnes; and e Six axial vibrators, each axial vibrator having a mass of about 4.8 tonnes.

In the example of Figures 1 to 5 the first linear path 124 is substantially parallel to the second linear path 126. This helps ensure the vibrations produce a moment around the longitudinal axis of the pile 200, rather than just shaking the pile 200 from side-to-side. However, it would be understood that other arrangements of vibrators are possible. For example, there may be three (or any number of} vibrators arranged equidistantly around the rim of the pile 200. To increase the number of vibrators in the vibrator assembly 100, there may be two or more vibrators at each circumferential position, for example a radially inner vibrator and a radially outer vibrator.

In the example of Figures 1 to 5 the first circumferential position is diametrically opposed to the second circumferential position. This helps ensure the vibrations produce a moment around the longitudinal axis of the pile 200, rather than just shaking the pile 200 from side-to-side. However, it would be understood that other arrangements of connection members are possible. For example, there may be three (or any number of) connection members arranged equidistantly around the rim of the pile 200.

In the example of Figures 1 to 5 the first vibrator is positioned so as to be circumferentially aligned with the first connection member 102 and the first linear path 124 is tangential to, or is parallel to a tangent of, the surface of the pile 200 at the first circumferential position. In the same manner, the second vibrator is positioned so as to be circumferentially aligned with the second connection member 104 and the second linear path 126 is tangential to, or is parallel to a tangent of, the surface of the pile 200 at the second circumferential position. This arrangement is particularly efficient at transferring reaction forces between the vibrators and the connection members 102, 104. However, it would be understood that different arrangements are possible. For example, in the example of Figure 6, the vibrators are positioned circumferentially between the connection members. Similarly, it may be advantageous to circumferentially align the axial vibrators with the connection members to ensure efficient transfer of force to the pile. However, other arrangements are also possible.

The vibrator assembly 100 may include a connection point for connection to a lifting device. The connection point may be a lifting eye for connection to a crane to allow deployment of the vibrator assembly 100. The vibrator assembly 100 may include a damping means provided so as to damp the vibrations between the vibrators and the connection point. The damping means may include a static mass or any other suitable damping means.

The connection point may be pivotally connected to the main body of the vibrator assembly 100, where the main body is the housing 122, the annular plate 400 or the like. In this manner, the vibrator assembly 100 may function as a pile upending tool. In this manner, the same tool may be used for upending, deployment and installation of the pile 200.

It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be applicable interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the invention.

Claims

Conclusions

1. A vibrator assembly for driving a pile into a subsurface, the vibrator assembly comprising: connecting means configured to cooperate with a pile, the connecting means comprising at least one connecting element; a first vibrator, the first vibrator comprising a first actuator connected to a first mass, the first actuator configured to, when activated, vibrate the first mass along a first linear path tangential to a surface of the pile or parallel to a tangent of a surface of the pile; and a second vibrator, the second vibrator comprising a second actuator connected to a second mass, the second actuator configured to, when activated, cause the second mass to vibrate along a second linear path tangential to the surface of the pile or parallel to a tangent to the surface of the pile, the first vibrator and the second vibrator being connected to the connecting means in such a manner that forces generated by the vibration of the first mass and of the second mass are transmitted to the pile through the connecting means.

2. The vibrator assembly of claim 1, wherein the at least one connecting element comprises: a first connecting element positioned to engage the surface of the pole at a first circumferential position; and a second connecting element positioned to engage the surface of the pole at a second circumferential position.

3. A vibrator assembly according to any preceding claim, wherein the first vibrator is positioned so as to be circumferentially aligned with a first circumferential position of the surface of the pile, the first linear path being tangential to the surface of the pile or parallel to a tangent of the surface of the pile at the first circumferential position, and the second vibrator is positioned so as to be circumferentially aligned with a second circumferential position on the surface of the pile, the second linear path being tangential to the surface of the pile or parallel to a tangent of the surface of the pile at a second circumferential position.

4. An assembly according to any one of the preceding claims, wherein the first linear path is substantially parallel to the second linear path.

5. The vibrator assembly of claim 2, wherein the first vibrator is positioned so as to be circumferentially aligned with the first connecting element, the first linear path being tangential to the surface of the pole or parallel to a tangent to the surface of the pole at the first circumferential position; and the second vibrator is positioned so as to be circumferentially aligned with the second connecting element, the second linear path being tangential to the surface of the pole or parallel to a tangent to the surface of the pole at the second circumferential position.

6. A vibrator assembly according to claim 2 or claim 3, wherein the first circumferential position is diametrically opposite the second circumferential position.

7. An assembly according to any preceding claim, wherein the first actuator is configured to vibrate the first mass along the first linear path at a frequency between about 40 Hz and about 80 Hz, the second actuator is configured to vibrate the second mass along the second linear path at a frequency between about 40 Hz and about 70 Hz.

8. A vibrator assembly according to any preceding claim, comprising a control system in communication with the first actuator and the second actuator, the control system being configured to activate the first actuator and the second actuator.

9. The vibrator assembly of claim 8, wherein the control system is configured to activate the first actuator and the second actuator in accordance with a vibration pattern, the vibration pattern being configured such that, during simultaneous vibration of the first mass and the second mass, the first mass is displaced along the first linear path in a direction corresponding to a circumferential direction around the surface of the pile, while the second mass is displaced along the second linear path in a direction corresponding to a circumferential direction around the surface of the pile.

10. Vibrator assembly according to claim 9, wherein the control system comprises a memory in which the vibration pattern is stored.

11. A vibrator assembly according to any preceding claim, wherein the vibrator assembly comprises at least one pressure sensor configured to monitor forces exerted on the pole by the vibrators.

12. A vibrator assembly according to any preceding claim further comprising at least one axial vibrator, each axial vibrator of the at least one axial vibrator comprising an actuator connected to a mass, the actuator being configured, when activated, to vibrate the mass along a path parallel to or coaxial with the longitudinal axis of the pole.

13. The vibrator assembly of claim 12, wherein the actuator of the axial vibrator is configured to vibrate the mass along the path at a frequency between about 25 Hz and about 40 Hz.

14. Vibrator assembly according to any one of the preceding claims, wherein the vibrator assembly comprises a connection point for establishing a connection with a hoisting device.

15. Vibrator assembly according to any one of the preceding claims, wherein the at least one connecting element is a hydraulic clamp.

16. A system for driving a pile into a subsurface, the system comprising: a vibrator assembly according to any one of the preceding claims; and a support structure for supporting the pile in a predetermined orientation in an installation position.

17. The system of claim 16 further comprising a sensor configured to determine the relative position of the pole with respect to the support structure during installation.

18. A kit of parts comprising: a vibrator assembly according to any one of claims 1 to 15; and a pole.

19. A kit of parts as claimed in claim 18, wherein the pile is a monopile or a modular pile (jacket pile).

20. A method of installing a pile in a subsoil, the method comprising: positioning a pile in an installation position; engaging the pile with connecting means of a vibrator assembly, the connecting means comprising at least one connecting element; activating a first actuator of a first vibrator to cause a first mass to vibrate along a first linear path tangential to a surface of the pile or parallel to a tangent of a surface of the pile; and activating a second actuator of a second curator to cause a second mass to vibrate along a second linear path tangential to the surface of the pile or parallel to a tangent of the surface of the pile;

wherein the first vibrator and the second vibrator are connected to the connecting means in such a manner that forces generated by the vibration of the first mass and of the second mass are transmitted to the pile through the connecting means.

21. A method according to claim 20, wherein the act of causing the pole to cooperate with connecting means comprises: causing the surface of the pole to cooperate at a first circumferential position with a first connecting element of the at least one connecting element; and causing the surface of the pole to cooperate at a second circumferential position with a second connecting element of the at least one connecting element.

22. A method according to claim 20 or claim 21, wherein the pile is a monopile or a modular pile (jacket pile).

23. A method according to any one of claims 20 to 22, wherein the installation position is offshore.

24. A method according to any one of claims 20 to 23, wherein, once the pile has been driven into the subsurface to a predetermined depth, the pile is configured to support a structure above the surface, for example a wind turbine.

25. A method according to any one of claims 20 to 24, wherein the method further comprises activating an actuator of an axial vibrator to vibrate a mass along a path parallel to or coaxial with the longitudinal axis of the pile.

26. Computer-readable instructions which, when executed by a computer, are provided with and adapted to perform a method according to any one of claims 20 to 25.

27. A non-volatile computer-readable storage medium storing instructions which, when executed by one or more electronic processors, cause the one or more electronic processors to perform a method according to any one of claims 20 to 25.