Field of the invention

The present invention relates to a pile lifting device for lifting a foundation object, such as a foundation pile or a sheet pile. The present invention further relates to a foundation assembly for inserting a foundation object, to a method of inserting a foundation object in the ground, to a method of withdrawing a foundation object out of the ground and to a method of manufacturing a foundation assembly.

State of the art

At present, foundation apparatuses are known throughout, for example from WO 2014/054942 A1. These foundation apparatuses are suspended from the winch of a crane or a leader and are configured to subject foundation objects, such tubular piles, sheet piles or concrete piles, to an insertion force, in order to drive them into the ground.

The foundation objects are generally elongate objects, which arrive at the building site in a horizontal orientation. Prior to inserting them into the ground, the foundation objects need to be handled to be moved towards a desired insertion location and up-ended into a vertical orientation. This is currently done typically by means of the foundation apparatus, by holding, especially clamping, and lifting the foundation object with the foundation apparatus.

This provides the situation that the entire weight of the foundation object needs to be suspended from the holding device, for example a clamping device. This requires the clamping device to be dimensioned much heavier, as compared to when the clamping only needs to take place during insertion, for transferring the insertion force onto the foundation object from the foundation apparatus.

Furthermore, some of the existing foundation apparatuses may not be formally certified as lifting equipment, thus possibly being unsafe when used for lifting foundation objects. Officially, these foundation apparatuses may not even used to lift foundation objects, which thus requires a second winch on the crane, or even a second crane, to position the foundation object underneath the foundation apparatus prior to insertion.

Both of the above drawbacks render the current insertion of foundation objects to be less favourable, requiring over-dimensioned foundation apparatuses or even multiple cranes.

Further reference is made to JP H10 114941 A1 , which discloses a crane having two winches, wherein one winch is used to lift a foundation apparatus and wherein another winch is used to lift a foundation object. The foundation object and the foundation apparatus can be moved relative to each other by selectively activating either one of the winches. This known system has the drawback of requiring two winches, whereas it may be preferred to lift the foundation object and the foundation apparatus by means of a single winch.

Object of the invention

It is therefore an object of the invention to provide a more efficient method and apparatus for inserting foundation objects into the ground, or at least to provide an alternative.

Detailed description

The present invention provides a pile lifting device for lifting a foundation object, such as a foundation pile or a sheet pile, the pile lifting device comprising: a lifting part, comprising a lifting yoke for suspending the pile lifting device from a crane, and a suspension arrangement for suspending the foundation object, an attachment part, movable relative to the lifting part and configured to be attached to a foundation apparatus to suspend the foundation apparatus from the crane, optionally, a linear bearing, in between the lifting part and the attachment part, configured to guide the linear movement between the lifting part and the attachment part, and a linear actuator device, configured to move the attachment part relative to the lifting part, to move the foundation apparatus relative to the suspension arrangement, between:

• a raised position, in which the attachment part is located at a distance from the suspension arrangement, and

• a lowered position, in which the attachment part is located proximate to the suspension arrangement.

The present pile lifting device is an add-on for foundation apparatuses, both existing apparatuses and newly-built ones. The pile lifting device is thereby configured to be suspended from the crane and the foundation apparatus is, in turn, suspended from the pile lifting device. According to the present invention, the foundation apparatus is thus not directly suspended from the crane.

During use for positioning of foundation objects, the foundation object is suspended from the pile lifting device and not from the foundation apparatus, which implies that the foundation apparatus is bypassed in terms of the weight of the foundation object, not being subjected to this weight. Only when it is needed to subject the foundation object to the insertion forces, the foundation apparatus can be moved towards the foundation object to effect holding of the foundation object and to allow for the transfer of the insertion force from the foundation apparatus to the foundation object.

The guiding of the weight of the foundation object through the pile lifting device provides that the weight of the foundation object does not need to be supported by the foundation apparatus during lifting and displacement of the foundation object. In fact, the foundation apparatus can be located at a distance from the foundation object during lifting. This provides the benefit that the foundation apparatus, especially the holding, e.g. clamping device thereof, does not need to be dimensioned to support the entire foundation object during lifting. Instead, the clamping device of the foundation apparatus only needs to be capable of holding the foundation object during insertion, which may allow for a smaller clamping device and thus a lower weight for the foundation apparatus, especially of the dynamic part thereof, e.g. the part vibrating during insertion of the foundation object, which reduces the amount of power, e.g. hydraulic power required for inserting the foundation object in the ground and allows for a more efficient operation with fewer energy losses occurring in the foundation apparatus.

Furthermore, only the pile lifting device is used for lifting of the foundation object, which means that only the pile lifting device may need to be certified for lifting purposes. This provides a further benefit, since the pile lifting device can be retro-fitted on existing foundation apparatuses, even foundation apparatuses that are not certified for lifting by themselves. This makes these existing foundation apparatuses, i.e. together with the pile lifting devices, suitable for lifting. It is therefore no longer necessary to lift via the potentially unsafe foundation apparatus. As such, operators of existing foundation apparatuses do not need to acquire a new foundation apparatus that might be certified for lifting, but only needs to retrofit a pile lifting device, which is obviously far less expensive.

Compared to existing situations, in which two cranes were needed for lifting and insertion the foundation object, the present pile lifting device offers a further benefit that only one crane may need to be used, which reduces cost significantly.

To achieve these benefits, the pile lifting device is composed of two main parts that are movable relative to each other, namely the lifting part and the attachment part. The lifting part is configured to be suspended from the crane. This may either be done from the hook of a conventional winch crane, or from the leader of a piling rig. The attachment to the crane provides that the lifting part is intended to carry all gravitational loads of the foundation object, the foundation apparatus and the pile lifting device that are all suspended from the crane.

The lifting yoke for attachment to the crane is typically provided at an upper end of the lifting part, whereas the suspension arrangement may be provided at a lower end of the lifting part. The weight of the foundation object, during use of the pile lifting device, is thus suspended from the lower end of the lifting part, which provides that the gravitational forces from the foundation object are transmitted upwardly through the lifting part, towards the crane.

The second main part of the pile lifting device is the attachment part, which is attached to the lifting part and which is movable relative to the lifting part, for example in a linear direction, such as a vertical direction during use of the pile lifting device. The attachment part is configured to be attached to the foundation apparatus during use in order to support the foundation apparatus relative to the lifting part. The foundation apparatus may be any type of foundation apparatus, such as a vibratory pile driver or an impact hammer.

The attachment part is provided distinct from the lifting part, which enables the relative movement between them and which provides that the foundation object does not need to be held by the foundation apparatus during lifting thereof. The foundation apparatus is thus not loaded by the foundation object during lifting.

The attachment part, and the foundation apparatus in accordance, is movable relative to the lifting part between the raised position and the lowered position, which positions are defined as they are during use of the pile lifting device, when the pile lifting device is suspended from the crane. The linear bearing may be configured to ensure a smooth movement of the attachment part with the foundation apparatus attached, relative to the lifting part.

In the raised position, the attachment part is moved upward relative to the lifting part, so that the foundation apparatus is moved upward and located at a distance from the suspension arrangement. This provides that the foundation apparatus, especially the holding, e.g. clamping device thereof, is moved away from the foundation object during use. The attachment part and the foundation apparatus are intended to be held in this raised position during lifting of the foundation object, so that the foundation object is unable to exert any forces on the foundation apparatus or vice versa, and that the foundation object can be substantially freely hanging to allow for correct positioning thereof.

The attachment part can be moved downward from the raised position into the lowered position, so that the attachment part is moved towards the suspension arrangement. Accordingly, the foundation apparatus attached to the attachment part can thus be moved towards the foundation object that is suspended from the suspension arrangement. The moving of the attachment part towards the lowered position may be effected when the foundation object is positioned correctly, at a desired insertion location. By lowering of the attachment part, the foundation apparatus can be moved towards the foundation object, in order to effect holding, e.g. clamping of the foundation object, to enable the transmission of insertion forces onto the foundation object.

The pile lifting device comprises a linear actuator device that is configured to effect the mutual movement between the attachment part and the lifting part. During use, the linear actuator device is thus configured to bring the foundation apparatus away from or towards the foundation object. The linear actuator device may be controlled remotely by an operator that also controls the entire foundation process from the crane. The linear actuator device may further be configured to transmit an upward pulling force from the crane, via the pile lifting device and the foundation apparatus, towards the foundation object, when it is desired withdraw the foundation object out of the ground.

In an embodiment, the lifting part comprises two opposed lifting arms, in between which the attachment part is located for receiving the foundation apparatus in between the lifting arms.

The lifting arms are arranged opposite to each other and spaced from each other in a horizontal direction, i.e. horizontal during use of the pile lifting device for lifting foundation objects. Preferably, the opposed lifting arms are symmetric to each other, relative to a vertical mirror plane. The lifting arms may thereby each extend vertically during use, each comprising a lifting yoke at their upper ends, with which they are suspended from the crane, and each comprising a suspension arrangement, for example embodied as a suspension shackle, at their lower ends, to be attached to the foundation object.

The lifting arms may be provided relatively rigid, in order to withstand the loading from the foundation object, since the lifting arms themselves do not need to be movable. Instead, the lifting arms are configured to be held stationary relative to the foundation object, merely serving the purpose of transferring gravitational forces from the foundation object towards the crane. For example, the lifting arms can each be attached to the foundation object via a respective tensile element.

With the lifting arms being spaced apart from each other, a central aperture is obtained between the lifting arms. According to this embodiment, the attachment part is provided such, that the foundation apparatus is held in this central aperture during use of the pile lifting device. This may further contribute to the symmetry of the thus obtained foundation assembly, having the relatively heavy foundation apparatus located centrally in between the lifting arms and centrally underneath the point from where the pile lifting device is suspended from the crane.

In a further embodiment, the lifting part comprises a central bridging element, which is arranged in between and releasably connected to the lifting arms. The central bridging element thus spans between the lifting arms, i.e. in a horizontal direction during use of the pile lifting device, and serves the purpose to hold the lifting arms apart in order to define the central aperture between them.

The central bridging element is releasable from the lifting arms, which implies that a first central bridging element with a first horizontal width can be exchanged for a second central bridging element with second width, larger than the first width. This may allow the width of the central aperture of the pile lifting device to be adjusted, i.e. increased, which allows for accommodation of a larger foundation apparatus, with a larger width. The exchangeable central bridging element may thus be provided that a single pile lifting device, having only a single pair of standard lifting arms, can be used more universally for foundation apparatuses of different sizes, e.g. widths. Moreover, a single pile lifting device may even be used for multiple different types of foundation apparatuses, for example both vibratory pile drivers and impact hammers.

In an embodiment, the attachment part comprises two opposed attachment struts, and each of the attachment struts is linearly movably attached to a respective one of the lifting arms.

The opposed attachment struts may each be provided at a respective lifting arm. As such, a single attachment strut may protrude into the central aperture between the lifting arms from opposite sides. The foundation apparatus may thereby be received in between the attachment struts, to be attached to the pile lifting device on opposite sides, with a respective attachment strut. The two attachment struts may contribute to the symmetry, since the weight of the foundation apparatus acting on the pile lifting device may be spread between both lifting arms, to be located centrally underneath the point from where the pile lifting device is suspended from the crane.

The linear actuator device may comprise a linear actuator at each of the lifting arms, each being functionally arranged in between a lifting arm and its respective attachment strut, so that each attachment strut can be moved individually relative to its lifting arm.

In an embodiment, the pile lifting device further comprises a linear bearing, for example a sliding bearing in between the lifting part and the attachment part, configured to guide the linear movement between the lifting part and the attachment part. The bearing is configured to ensure a smooth movement of the attachment part with the foundation apparatus attached, relative to the lifting part.

Preferably, the pile lifting device comprises a linear bearing in each of its lifting arms e.g. both linear bearings being aligned parallel to each other. Each of the bearings may thereby be arranged in between a lifting arm and the attachment strut of that lifting arm. The linear bearings can be sliding bearings, each being formed by interlocking surface that enable mutual displacement in a single direction, e.g. the vertical direction, and that prevent mutual movements in other, e.g. horizontal directions.

In an embodiment, the linear actuator device is a hydraulic actuator device. The use of a hydraulic actuator device may be beneficial, since the foundation apparatus may be powered hydraulically as well, so that part of the existing infrastructure may be used to implement the pile lifting device in existing foundation apparatuses. Alternatively, however, the linear actuator device may comprise a spindle, a rack-and- pinion or a worm transmission. These types of transmissions may typically be able to convert a rotation of a first component about a first axis, into a mutual translation of a second component relative to the first component. This translation may, in the case of a spindle or worm transmission, be in a direction parallel to the first axis or in a direction perpendicular to the first axis for the rack-and-pinion transmission.

As a further alternative, the linear actuator may comprise an actuator winch of which a line can be connected to the attachment part. The actuator winch may be provided in the crane from which the pile lifting device is suspended, i.e. with a lifting winch. The lifting winch can thereby be used to lift the pile lifting device and the foundation object during use, whereas the actuator winch may be configured to lift the attachment part and the foundation apparatus, to enable the mutual movement between the lifting part and the attachment part.

In a further embodiment, the hydraulic actuator device comprises at least one hydraulic cylinder, comprising a barrel and a piston rod, wherein the barrel is connected to the attachment part and wherein the piston rod is connected to the lifting part, or vice versa.

The hydraulic cylinders are, during use configured to receive pressurized hydraulic fluid in the barrel on a first side or a second side of the piston rod. The hydraulic fluid may effect a displacement of the piston rod relative to the barrel, to effect the mutual movement between the lifting part and the attachment part.

In a further embodiment, in which the attachment part comprises the two opposed attachment struts and in which each of the attachment struts is linearly movably attached to the respective one of the lifting arms, the hydraulic actuator device comprises at least one of the hydraulic cylinders for each of the lifting arms, each configured to move the respective attachment strut relative to its lifting arm.

At least one hydraulic cylinder may thereby be present in each pair of lifting arms and associated attachment struts, to move a respective attachment strut relative to its lifting arm. The piston rods of the cylinders may be attached to the top ends of the lifting arms and the barrels of the cylinders may be attached to the attachment struts with upper ends thereof. The attachment struts may thereto comprise a through passage, aligned in the vertical direction during use, through which the cylinder barrels can extend alongside the lifting arms.

According to a second aspect, the present invention provides a foundation assembly for inserting a foundation object, such as a foundation pile or a sheet pile, in the ground, wherein the foundation assembly comprises a foundation apparatus, comprising: a holding device for holding, e.g. clamping, the foundation object during insertion in the ground, a carter, connected to the holding device, configured to subject the holding device and the foundation object to an insertion force, a suppressor housing, elastically connected to the carter, for suspending the holding device and the carter, characterized in that, the foundation assembly further comprises the pile lifting device as disclosed herein, wherein the foundation apparatus, e.g. the suppressor housing, is attached to the attachment part of the pile lifting device, and wherein the pile lifting device is configured to move the foundation apparatus relative to the suspension arrangement, between:

• the raised position, in which, during use, the holding device is spaced at a distance from the foundation object, and

• the lowered position, in which, during use, the holding device contacts the foundation object to hold, e.g. clamp, the foundation object.

The foundation assembly according to the second aspect may comprise one or more of the features and/or benefits disclosed herein in relation to the pile lifting device according to the present invention, in particular as recited in the appended claims.

The foundation assembly is composed of a foundation apparatus and the pile lifting device. The foundation apparatus may be any type of foundation apparatus, such as a vibratory pile driver or an impact hammer. The foundation apparatus does not need to be certified for lifting, i.e. it may be an existing foundation apparatus, since only the pile lifting device may need to be certified for lifting purposes.

In case the foundation apparatus is provided as an impact hammer, the pile lifting device may be attached to an outer housing of the hammer, in which a drop weight is accommodated as a carter to strike the foundation object during use, to obtain a downward impact insertion force. The holding device may thereby, for example, comprise a sleeve to surround the foundation object, to ensure aligned striking of the foundation object with the drop weight.

Should the foundation apparatus be provided as a vibratory pile driver, then the holding device may concern a clamping device, configured to clamp the foundation object during insertion in the ground. The clamping may be beneficial to ensure proper transfer of the vibrational insertion force from the foundation apparatus towards the foundation object. The carter is configured to generate this vibrational force during insertion, for example by means of a plurality of rotating eccentric masses. The suppressor housing of the foundation apparatus is attached to the carter in an elastic manner, so that vibrations from the carter and the clamping device are not transmitted towards the suppressor housing, but dampened substantially instead.

The pile lifting device may be attached to the suppressor housing of the foundation apparatus, so that the foundation apparatus is suspended from the pile lifting device. Opposed to existing foundation apparatuses, which are typically suspended from a crane directly, is the foundation apparatus in the present foundation assembly only suspended from the crane indirectly, via the pile lifting device. The pile lifting device itself is configured to support the foundation object, so that no lifting of the foundation object is required through the foundation apparatus. This implies that the foundation apparatus is bypassed in terms of the weight of the foundation object.

The foundation apparatus is, during use, movable relative to the foundation object by means of the pile lifting device. During lifting of the foundation object, the foundation apparatus is held in the raised position with the pile lifting device. This ensures that the foundation apparatus, especially the clamping device thereof, is moved upward and located at a distance from the foundation object. This provides that the foundation apparatus, especially the clamping device thereof, is moved away from the foundation object. The attachment part and the foundation apparatus are intended to be held in this raised position during lifting of the foundation object, so that the foundation object is unable to exert any forces on the foundation apparatus or vice versa, and that the foundation object can be substantially freely hanging to allow for correct positioning thereof.

The attachment part can be moved downward from the raised position into the lowered position, so that the foundation apparatus is moved towards the foundation object with its clamping device. The downward moving of the foundation apparatus may be effected when the foundation object is positioned correctly, at a desired insertion location. By lowering of the foundation apparatus, the clamping device may clamp the foundation object, to enable the transmission of insertion forces onto the foundation object.

In a further embodiment, the suppressor housing is located centrally in the pile lifting device, e.g. located centrally in between the lifting arms. The foundation apparatus may thereby be located in the central aperture, to ensure that the overall foundation assembly, with the foundation object underneath it, can be provided relatively symmetrically to improve insertion of the foundation object.

In an embodiment, the foundation assembly further comprises one or more tensile elements, connected to the suspension arrangement and configured to be connected to the foundation object for lifting the foundation object with the pile lifting device. The tensile elements may be provided as steel cables, chains or the like, which are connected to the pile lifting device at the suspension arrangement and which are to be fastened to the foundation object during use.

During lifting of the foundation object, the foundation object may be fully suspended from the pile lifting device through the tensile elements, so that the entire weight of the foundation object is supported by the tensile elements. However, when the foundation object is displaced towards the desired insertion location and when the foundation apparatus is lowered to clamp the foundation object, the pile lifting device may be lowered by the crane in its entirety, to let the foundation object rest on the ground in full. This will relax the tensile elements, so that it can be prevented that the vibrational insertion force is transmitted from the foundation object towards the pile lifting device, through the otherwise tensioned tensile elements.

According to a third aspect, the present invention provides a method of inserting a foundation object, such as a foundation pile or a sheet pile in the ground by means of the foundation assembly as disclosed herein, the method comprising the steps of: suspending the foundation object from the suspension arrangement, while the pile lifting device is in the raised position, displacing, with the pile lifting device or the foundation apparatus, the foundation object to a desired insertion location, moving the pile lifting device into the lowered position, holding, e.g. clamping, the foundation object with the holding device, and subjecting the foundation object to the insertion forces to insert the foundation object in the ground.

The method according to the third aspect may involve one or more of the features and/or benefits disclosed herein in relation to the pile lifting device or the foundation assembly according to the present invention, in particular as recited in the appended claims.

For inserting the foundation object in the ground, either onshore, offshore or below sea level, use is made of the foundation assembly, which comprises a foundation apparatus and the pile lifting device according to the present invention. The foundation assembly may be suspended from a crane, for example either a hook of a conventional winch crane, or from the leader of a piling rig. The foundation objects may typically be supplied in a horizontal orientation, so that the step of placing may comprise both the upending of the foundation object and the displacement towards the desired insertion location.

The foundation object is first suspended from the suspension arrangement of the pile lifting device, for example being attached to the lifting arms of the lifting part by means of tensile elements. When the foundation object is suspended, the attachment part with the foundation apparatus attached to it is in the raised position, so that the holding, e.g. clamping device is moved away from the foundation object and that the foundation object can freely hang from the pile lifting device, without being suspended by the foundation apparatus.

When the foundation object has reached the desired insertion location, it can be placed on the ground, so that no longer the entire weight of the foundation object is suspended from the pile lifting device, but that the foundation object at least partly comes to rest on the ground. The pile lifting device is then moved towards the lowered position, so that the foundation apparatus is moved towards the foundation object, to contact an upper end of the foundation object with the holding device of the foundation apparatus.

Then, the foundation object is held with the holding device. Should the holding device be provided with a sleeve, the sleeve can be moved over the upper end of the foundation object to sidewardly confine the foundation object inside the sleeve. For inserting the foundation object, it may then be subjected to a downward impact insertion force to drive the foundation object in the ground.

In case the holding device is provided as a clamping device, the clamping device may clamp the foundation object to hold it in place. Next, the foundation apparatus may subject the foundation object to vibratory insertion forces to oscillate the foundation object in order to drive the foundation object in the ground.

In an embodiment, the insertion method further comprises , after the step of holding and before the step of subjecting, the steps of: moving the pile lifting device into the raised position, and lowering the pile lifting device relative to the foundation object.

This embodiment may provide that when the foundation object is placed at the desired insertion location and when the foundation apparatus is lowered to clamp the foundation object, the pile lifting device may be lowered by the crane in its entirety, to let the foundation object rest on the ground in full. This will relax the tensile elements between the pile lifting device and the foundation object, so that it can be prevented that the vibrational insertion force is transmitted from the foundation object towards the pile lifting device, through the tensile elements.

According to a fourth aspect, the present invention provides a method of withdrawing a foundation object, such as a foundation pile or a sheet pile out of the ground by means of the foundation assembly as disclosed herein, the method comprising the steps of: connecting the foundation object to the suspension arrangement, clamping the foundation object with the clamping device, while the pile lifting device is in the lowered position, subjecting the foundation object to withdrawal forces to withdraw the foundation object out of the ground, upwardly pulling the pile lifting device to pull the foundation object out of the ground, moving the pile lifting device into the raised position, suspending the foundation object from the suspension arrangement, while the pile lifting device is in the raised position, and displacing, with the pile lifting device or the foundation apparatus, the foundation object towards a desired storage location.

The method according to the fourth aspect may involve one or more of the features and/or benefits disclosed herein in relation to the pile lifting device or the foundation assembly according to the present invention, in particular as recited in the appended claims. For withdrawing the foundation object, the method may involve the steps of the insertion method according to the present invention in a substantially reverse order.

Finally, according to a fifth aspect, the present invention provides a method of manufacturing a foundation assembly, comprising the steps of: providing a foundation apparatus, providing the pile lifting device as disclosed herein, and attaching the pile lifting device to the foundation apparatus, e.g. to a suppressor housing of the foundation apparatus, with the attachment part thereof.

The method according to the fifth aspect may involve one or more of the features and/or benefits disclosed herein in relation to the pile lifting device or the foundation assembly according to the present invention, in particular as recited in the appended claims.

The present method is configured to result in a foundation assembly that is composed of a foundation apparatus and the pile lifting device. The foundation apparatus may be any type of foundation apparatus, such as a vibratory pile driver or an impact hammer. The foundation apparatus does not need to be certified for lifting, i.e. it may be an existing foundation apparatus, even a foundation apparatus that is not certified for lifting by itself. This makes that only the pile lifting device may need to be certified for lifting purposes.

In case the foundation apparatus is provided as an impact hammer, the pile lifting device may be attached to an outer housing of the hammer, in which a drop weight is accommodated as a carter to strike the foundation object during use, to obtain a downward impact insertion force.

Should the foundation apparatus be provided as a vibratory pile driver, it typically comprises a clamping device, configured to clamp the foundation object during insertion in the ground. The clamping may be beneficial to ensure proper transfer of the vibrational insertion force from the foundation apparatus towards the foundation object. The foundation apparatus may then further comprise a carter, configured to generate a vibrational force during insertion, for example by means of a plurality of rotating eccentric masses. The suppressor housing of the foundation apparatus is attached to the carter in an elastic manner, so that vibrations from the carter and the clamping device are not transmitted towards the suppressor housing, but dampened substantially instead. The pile lifting device may be attached to the suppressor housing of the vibratory foundation apparatus, so that the foundation apparatus becomes suspended from the pile lifting device. Opposed to existing foundation apparatuses, which are typically suspended from a crane directly, is the foundation apparatus in the present foundation assembly only suspended from the crane indirectly, via the pile lifting device. The pile lifting device itself is configured to support the foundation object, so that no lifting of the foundation object is required through the foundation apparatus. This implies that the foundation apparatus is bypassed in terms of the weight of the foundation object.

Brief description of drawings

Further characteristics of the invention will be explained below, with reference to embodiments, which are displayed in the appended drawings, in which:

Figure 1 schematically depicts an embodiment of the pile lifting device according to the present invention, shown in its raised position,

Figure 2 shows the pile lifting device in its lowered position, and

Figures 3A - 3D show an embodiment of the foundation assembly according to the present invention in various steps of the present insertion method.

Throughout the figures, the same reference numerals are used to refer to corresponding components or to components that have a corresponding function.

Detailed description of embodiments

Figure 1 schematically depicts an embodiment of the pile lifting device according to the present invention, to which is referred with reference numeral 1. The pile lifting device 1 is intended for lifting of a foundation object, which is embodied as a tubular foundation pile 100 in the present figures.

The pile lifting device 1 comprises a lifting part 10 with a lifting yoke for suspending the pile lifting device 1 from a crane. In the present embodiment, the lifting yoke comprises two opposed lifting shackles 11 at an upper end of the lifting part 10. The pile lifting device 1 is configured to hang from the crane by means of the lifting shackles 11, so that the entire weight of the pile lifting device 1, as well as the weight of the pile 100 and a foundation apparatus 51, is guided through the lifting part 10 towards the crane.

The lifting part 10 comprises two opposed lifting arms 12, which are arranged opposite to each other and spaced from each other in a horizontal direction H. The opposed lifting arms 12 are symmetric to each other and define a central aperture in between them. The lifting arms 12 extend in a vertical direction V during use, i.e. as shown in figures 3A - 3D. The lifting shackles 11 are each provided at the upper end of a respective lifting arm 12. Furthermore, the lifting arms 12 each comprise a suspension arrangement at their lower ends, which are embodied as suspension shackles 13. The suspension shackles 13 are intended to be connected to the pile 100 by means of tensile elements 2, as is shown in figures 3A - 3D. The weight of the pile 100, during use of the pile lifting device 1, is thus suspended from the lifting part 10 and all gravitational forces from the pile 100 are transmitted upwardly through the lifting part 10, towards the crane.

The lifting part 10 further comprises a central bridging element 14, which is arranged in between the lifting arms 12, to span in between the lifting arms 12 in the horizontal direction H during use of the pile lifting device 1. The central bridging element 14 is releasably connected to the lifting arms 12. A first central bridging element with a first horizontal width can therefore be exchanged for a second central bridging element with second width. This may allow the width of the central aperture of the pile lifting device 1 to be adjusted, to allow for accommodation of different foundation apparatuses, with different widths.

The pile lifting device 1 further comprises an attachment part 20, which comprises two attachment struts 21. The attachment struts 21 are movable relative to the lifting part 10 and are configured to be attached to a foundation apparatus 51, to suspend the foundation apparatus 51 from the crane indirectly. The attachment struts 21 of the attachment part 20 are movable relative to the lifting part 10 in a linear direction, parallel to the vertical direction V during use. The attachment struts 21 are configured to be attached to a foundation apparatus 51 during use, as shown in figures 3A - 3D, in order to support the foundation apparatus 51 relative to the lifting part 10. The attachment struts 21 project into the central aperture between the lifting arms 12, so that the foundation apparatus 51 can be held centrally in between the lifting arms 12.

The pile lifting device 1 comprises sliding bearings 15 in each of its lifting arms 12, which are each arranged in between a lifting arm 12 and the attachment strut 21 of that lifting arm 12. The sliding bearings 15 are configured to guide the linear movement between the lifting part 10 and the attachment part 20.

The attachment part 20 of the pile lifting device 1 is movable relative to the lifting part 10 between a raised position, as shown in figure 1, and a lowered position, shown in figure 2. In the raised position, the attachment struts 21 of the attachment part 20 are located at a distance from the suspension shackles 13 so that the foundation apparatus 51 can be spaced at a distance from the pile 100. In the lowered position, the attachment struts 21 of the attachment part 20 are located proximate to the suspension shackles 13 so that the foundation apparatus 51 can be located close to the pile 100.

The pile lifting device 1 further comprises a hydraulic linear actuator device that is configured to effect the mutual movement between the attachment part 20 and the lifting part 10. The hydraulic actuator device comprises a hydraulic cylinder 30 at each of the lifting arms 12, each being functionally arranged in between a lifting arm 12 and its respective attachment strut 21, so that each attachment strut 21 can be moved individually relative to its lifting arm 12. The hydraulic cylinders 30 each comprise a barrel 31 , connected to the respective attachment strut 21, and a piston rod 32, connected to the respective lifting arm 12.

The hydraulic cylinders 30 are, during use configured to receive pressurized hydraulic fluid in the barrel 31 on a first side or a second side of the piston rod 32. The hydraulic fluid may effect a displacement of the piston rod 32 relative to the barrel 31, to effect the mutual movement between the lifting part 10 and the attachment part 20, to bring the foundation apparatus 51 away from or towards the pile 100.

In figures 3A - 3D, the pile lifting device 1 is shown with a foundation apparatus 51 attached to it, to form an embodiment of the foundation assembly 50 according to the present invention. The foundation apparatus 51 is a vibratory pile driver, which comprises a clamping device 52, configured to clamp the pile 100 during insertion in the ground. The clamping is established to ensure proper transfer of a vibrational insertion force from the foundation apparatus 51 towards the pile 100. The foundation apparatus 51 comprises a carter 53, configured to generate the vibrational force during insertion by means of a plurality of rotating eccentric masses. Finally, the foundation apparatus 51 comprises a suppressor housing 54, which is attached to the carter 53 in an elastic manner, so that vibrations from the carter 53 and the clamping device 52 are not transmitted towards the suppressor housing 54 and the pile lifting device 1 , but dampened substantially instead.

The pile lifting device 1 is attached to the suppressor housing 54 of the foundation apparatus 51 , so that the foundation apparatus 51 is suspended from the pile lifting device 1 and not from the crane directly. This implies that no lifting of the pile 100 is required through the foundation apparatus 51 and that the foundation apparatus 51 is bypassed in terms of the weight of the pile 100. The suppressor housing 54 is thereby located centrally in between the lifting arms 12, to substantially improve the symmetry of the assembly 50.

During use, the foundation apparatus 51 is movable relative to the pile 100 by means of the pile lifting device 1. During lifting of the pile 100, the foundation apparatus 51 is held in the raised position with the pile lifting device 1 , in order to move the clamping device 52 away from the pile 100. The attachment part 20 can further be moved downward from the raised position into the lowered position, so that the foundation apparatus 51 is moved towards the pile 100 with its clamping device 52.

In figure 3A, the assembly 50 is shown at the onset of the present insertion method, in which the pile 100 is arranged in horizontal orientation, which requires the pile 100 to be upended prior and to be displaced towards a desired insertion location. To effect upending and placement, the foundation assembly 50 is suspended from the hook of a conventional winch crane, but may alternatively be suspended from the leader of a piling rig or the like.

The pile 100, in turn, is suspended from the suspension shackles 13 of the lifting arms 12 by means of the tensile elements 2. The tensile elements 2 are provided as steel cables and extend, with their ends opposite to the suspension shackles 13, through openings that are cut in the pile 100.

During lifting of the pile 100, i.e. during the upending shown in figure 3A and the displacing towards the desired insertion location in figure 3B, the pile 100 becomes fully suspended from the pile lifting device 1 through the tensile elements 2, so that the entire weight of the pile 100 is supported by the tensile elements 2. The attachment part 20 of the pile lifting device 1 , with the foundation apparatus 51 attached to it, is thereby held in the raised position, so that the clamping device 52 is moved away from the pile 100 and that the pile 100 freely hangs from the pile lifting device 1, without being suspended by the foundation apparatus 51.

After the placement of the pile 100 at the desired insertion location, the pile 100 is placed on the ground, so that no longer the entire weight of the pile 100 is suspended from the pile lifting device 1, but that the pile 100 at least partly comes to rest on the ground. The attachment part 20 of the pile lifting device 1 is then brought in the lowered position to lower the foundation apparatus 51 towards the pile 100. The clamping device 52 of the foundation apparatus 51 thereby clamps the pile 100, to hold the pile 100 in place, as shown in figure 3C.

After lowering the foundation apparatus 51 relative to the lifting part 10 of the pile lifting device 1 , the foundation apparatus 51 comes to rest on the pile 100. In turn, the pile lifting device 1 is lowered by the crane in its entirety, as is shown in figure 3D, and the attachment part 20 is moved back into the raised position. This will leave the pile 100 resting on the ground in full, whilst the tensile elements 2 between the pile lifting device 1 and the pile 100 are relaxed.

Finally, the foundation apparatus 51 is activated to generate vibrations upon rotation of eccentric masses in the carter 53, in order to subject the pile 100 to the vibratory insertion forces, to oscillate the pile 100, which eventually drives the pile 100 in the ground. The relaxation of the tensile elements 2, following the lowering of the pile lifting device 1 , will thereby prevent that the vibrational insertion force is transmitted from the pile 100 towards the pile lifting device 1 and the crane.