Large-diameter pile driving method and system

Abstract

And the large-diameter steel pile column (1) is vertically driven into the ground. A pile driving device (10) is used at the top end of the pile. The pile driving device comprises a heading assembly (20) having an annular contact surface (21) resting on the top end of the pile and an annular anvil surface located above the annular contact surface. The steel impact weight (30) has a mass of at least 100 tons. The impact weight (30) is lifted to a desired initial height position by a lifting system (60). A quick release mechanism (70) is operated to effect quick release of the lifting system such that the impact weight falls from the initial height position onto the anvil face (22) of the heading assembly (20). The impact weight comprises a tubular impact weight preferably implemented from steel.

Description

Technical Field

[0001] The present invention relates to the field of vertically driving hollow, open-ended, large-diameter steel piles into the ground, the piles having a cylindrical top portion with a top portion wall thickness between an inner diameter and an outer diameter, wherein the outer diameter penetrates at least 5 meters into the soil. The invention is particularly advantageous for driving monolithic piles for offshore wind turbines into the seabed. Practical embodiments currently envisaged include monolithic piles with a diameter between 5 and 12 meters and a length between 60 and 120 meters. The weight of the monolithic piles can be greater than 1,000 tons, with monolithic piles of approximately 2,500 tons (12 meters outer diameter, 120 meters length) currently proposed. Background Art

[0002] In current monolithic pile installation practice, a single, so-called accelerated hydraulic hammer is typically used. This hydraulic hammer is a pile driver in which an impact weight is hydraulically accelerated downward by gas pressure to achieve accelerations well above 1 G (normal acceleration under gravity). These known devices are capable of achieving accelerations up to twice the free-fall rate, thus reaching 2 G. Currently, such pile driving devices are available in configurations capable of delivering over 4000 kJ per stroke, and even up to 5500 kJ per stroke, such as the Menck MHU 4400S, or the IQIP IQ4 or IQIP IQ6 hammers. However, their practical application for driving large-diameter monolithic piles appears to suffer from various drawbacks.

[0003] In a known application for driving monolithic piles into the seabed, a single hydraulic hammer is centrally located on a head assembly, which rests with its contact surface on the top of the monolithic pile. The head assembly has a very strong, disc-shaped portion that distributes the impact energy from an anvil surface in the center of the head assembly to an annular contact surface with a diameter that is the same as the diameter of the top of the monolithic pile. This requires a very strong design of the head assembly.

[0004] Another method for driving large-diameter piles (e.g., monolithic piles) is proposed in WO2006 / 010758. Here, multiple hydraulic hammer pile driving devices are placed on top of a single monolithic pile. Each device has its own impact weight and an associated acceleration mechanism based on gas pressure via a hydraulic device acting on the impact weight. Each hammer is mounted on a section at the open top of the pile. This method requires extreme synchronization of the hammer devices, which is impractical.

[0005] WO2020 / 153838 proposes an alternative method for driving piles of large diameter. Here, the drop weight falls solely under the action of gravity, and therefore falls at 1G. In an embodiment, a single drop weight used for pile driving has a mass of at least 50 tons, for example 100 tons or even several hundred tons. In an embodiment, the drop weight consists of a support platform on which steel counterweight elements are stacked. The platform is guided by a vertical tower. In an embodiment, the drop weight assembly is lifted by a lifting system comprising a plurality of hydraulic lifting cylinders and associated hydraulic pumps. The quick release system comprises one or more quick release valves, which open to allow the hydraulic fluid to be quickly discharged from the lifting cylinders. The hydraulic fluid of the one or more lifting cylinders can be circulated through a heat exchanger system to cool the hydraulic fluid. For example, the heat exchanger is supplied with seawater to cool the circulating hydraulic fluid when the pile is installed in the seabed. Summary of the Invention

[0006] The object of the present invention is to provide an alternative pile driving device for driving large diameter piles into soil, for example driving monolithic piles into the seabed. In particular, the object of the present invention is to provide a pile driving device that has limited complexity (e.g. with regard to manufacturing), high reliability and / or is easy to integrate into the overall process of monolithic pile installation.

[0007] According to a first aspect of the invention, a pile driving method is provided for driving a large diameter hollow and open-ended steel pile vertically into the ground, the pile having a cylindrical top portion with a top portion wall thickness between an inner diameter and an outer diameter, wherein the outer diameter is at least 5 meters, for example a monolithic pile for an offshore wind turbine into soil, for example into the seabed.

[0008] Wherein, a pile driving device arranged on the top of the pile is used, and the pile driving device comprises:

[0009] a driving assembly having an annular contact surface resting on the top end of the pile and an annular anvil surface above the annular contact surface,

[0010] a steel impact weight having a mass of at least 100 tons, for example greater than 200 tons, which impact weight is vertically movable above the anvil surface of the driving head assembly,

[0011] - a vertical guide structure configured to guide the impact weight vertically,

[0012] wherein the driving assembly is configured as an energy transfer assembly between the annular anvil surface and the contact surface for transferring energy from the falling impact weight to the annular contact surface and thereby to the pile top,

[0013] - a lifting system configured to bring the impact weight into an initial height position relative to the annular anvil surface of the driving head assembly,

[0014] - a quick release system adapted to achieve a quick release of the lifting system so that the impact weight falls from said initial height position onto the anvil surface of the driving assembly,

[0015] wherein the method comprises a repeated loop wherein:

[0016] -The impact counterweight is lifted to the initial height position through the lifting system,

[0017] -Operating the quick release mechanism to achieve a quick release of the lifting system, causing the impact weight to fall from the initial height position onto the anvil surface of the driving head assembly, wherein the energy from the falling impact weight is transferred to the contact surface of the driving head assembly and thereby to the top end of the pile, causing the pile to be driven deeper into the soil.

[0018] According to a first aspect of the present invention, the impact weight comprises or is embodied as a tubular impact weight made of steel.

[0019] In an embodiment, the tubular impact weight has an inner and outer diameter such that, in vertical projection, the tubular impact weight and the wall thickness of the top portion of the pile overlap. This arrangement allows the impact energy of the falling impact weight to travel vertically through the head assembly and then into the wall thickness of the top portion of the (monolithic) pile. This avoids undue stress in the path of the impact energy and allows for optimal driving efficiency.

[0020] In one embodiment, an acceleration mechanism is provided that accelerates the falling counterweight downward at an acceleration greater than 1G (e.g., adjustable between 1G and 2G). For example, a plurality of accelerator devices are provided in the pile driving device, arranged in a circular array and engaging a tubular impact counterweight at distributed locations. For example, each of these plurality of accelerator devices is based on an acceleration mechanism known from the aforementioned hydraulic hammer, such as that shown in US Pat. No. 4,601,349. For example, each accelerator device comprises a cylinder having a cylinder body and a piston / piston rod, wherein a pressurized gas-filled chamber pushes the piston / piston rod downward. In contrast to the accelerator hammer device disclosed in WO 2006 / 010758, in which each accelerator device has its own impact counterweight, the plurality of accelerator devices now engage a common impact counterweight. Since the accelerator devices are now mechanically coupled via a rigid impact counterweight, this has advantages in terms of synchronization of the accelerator devices.

[0021] In one embodiment, the pile driving device lacks an acceleration mechanism, allowing the impact weight to fall under gravity without further acceleration. Compared to accelerated embodiments, this gravity-based descent in the present invention results in a relatively long duration of energy transfer. This improves pile driving efficiency and can help reduce pile driving noise, which is particularly relevant for offshore pile driving.

[0022] Preferably, the impact weight is embodied as a tubular impact weight made of steel, for example cast or welded from steel plates, for example welded from semicircular steel plates, for example with a wall thickness of between 10 cm and 20 cm.

[0023] In an embodiment, the tubular impact weight has a circular cross-section, for example welded from semicircular steel plates. In other embodiments, the tubular impact weight is welded from flat plates to form a polygonal cross-section, for example a 16-sided or 32-sided polygon.

[0024] Preferably, the steel tubular impact weight has an inner peripheral side and an outer peripheral side with a wall thickness between the inner and outer peripheral sides, and is thus made of solid steel between the inner and outer peripheral sides.

[0025] In an embodiment, the tubular impact weight has a lower section having a first wall thickness and an upper section having a second wall thickness, the second wall thickness being greater than the first wall thickness.

[0026] Preferably, a lifting system is connected to the upper part of the tubular impact weight, for example a lifting cylinder having a piston rod, one end of which is connected to the upper section of the tubular impact weight.

[0027] Preferably, the tubular impact weight is free of any internal support members extending through the opening defined by the tubular impact weight. This avoids, for example, undue localised stresses where such support members abut the tubular component.

[0028] In an embodiment, the tubular impact weight has an inner and outer diameter such that, in vertical projection, the tubular impact weight and the wall thickness of the top portion of the pile overlap. This arrangement allows the impact energy of the falling impact weight to travel vertically through the head assembly and then into the wall thickness of the top portion of the (monolithic) pile. This avoids undue stress in the path of the impact energy and allows for optimal driving efficiency.

[0029] In a practical embodiment, as in the prior art, the top portion of the pile is open, just like the bottom.

[0030] In an embodiment, the tubular impact weight is hollow and open ended, and thus effectively implements a solid steel impact weight ring.

[0031] In an embodiment, a pile driving device including a tubular impact weight has an open-ended central passage, for example to allow access from above to the interior of a monolithic pile by the pile driving device. Preferably, the central opening has a diameter of at least 2 meters, for example corresponding to at least 50%, for example at least 75%, of the inner diameter of the top portion of the pile. This allows sufficient access from above to the interior of the monolithic pile by the pile driving device, which has practical benefits.

[0032] For example, during pile driving or in subsequent steps before removing the pile driving device from the (single) pile, other activities involving access to the interior of the pile via the central passage are performed. For example, the central passage is used to access the interior of the pile by one or more of the following: injection equipment, soil removal equipment, drilling equipment, vibration equipment, grouting equipment including the lines associated with these equipment. For example, the passage is used to access the stone removal device when, for example, the pile hits a relatively large stone during pile driving.

[0033] For example, the central passage is used to allow drilling equipment to be lowered along the pile to the seabed. This is particularly advantageous when the pile has struck a large rock embedded in the seabed during the pile driving operation. Normally, the pile must be lifted and removed from the installation site so that the drilling equipment can be used to remove the rock or other obstruction. By having a central passage, the drilling equipment can be lowered to the seabed and the obstruction removed without having to lift and remove the pile.

[0034] For example, the central channel is used to engage a pile lifting tool with the top portion of the pile, wherein the pile lifting tool is configured to be introduced into the central channel and then engage with the top portion of the pile.

[0035] For example, the pile has an inwardly facing top flange, eg with bolt holes. Preferably, the contact surface is located directly above the top part wall of the monolithic pile to avoid that the top flange is (over)tensioned during driving of the pile.

[0036] For example, during pile travel, if the pile driver is closed, as the pile travels deeper into the seabed, any air inside the pile and the pile driver is compressed, which increases the pressure inside the pile and the pile driver. This pressure may become high enough to lift the pile driver from the top of the pile, which may cause significant damage to the pile driver, the pile and surrounding structures, as well as pose a danger to personnel. By having an open-ended central passage, which allows air to escape from the pile and the pile driver, no pressure builds up, thereby increasing the safety of the operation.

[0037] For example, the central channel can be used to reduce the chance of a pile traveling.The central channel allows for the use of a pile traveling prevention member that can be disposed inside the central channel and configured to engage a flange at the top end of the pile.

[0038] In an embodiment, the pile travel preventing member comprises a damping member suspended from the pile driver or alternatively from a crane, and an engaging member suspended from the damping member and configured to engage an inwardly facing top flange of the pile.

[0039] In an alternative embodiment, the pile travel prevention member is embodied as a cable having a first end and a second end, wherein the first end is suspended from the pile driver or alternatively from a crane, and wherein the second end is provided with an engagement member configured to engage an inwardly facing top flange of the pile, wherein during normal operation the cable is slack, and when the pile is driven deeper into the ground by the pile driver, the length of the cable increases such that the cable does not exert a force on the pile, and only when pile travel occurs does the cable become taut and exert an upward force on the pile, thereby preventing pile travel.

[0040] In an embodiment, the driving assembly is configured to expose a portion of the inwardly facing top flange. In an embodiment, this arrangement can allow the flange to be gripped by a gripper of a pile lifting tool. In an embodiment, the driving assembly has an inner diameter greater than the inwardly facing top flange, such that a peripheral portion of the flange is exposed.

[0041] In an embodiment, the tubular impact weight has a wall thickness of between 10 centimeters and 20 centimeters.

[0042] In an embodiment, the tubular impact weight has a height between 4 and 12 meters, such as between 6 and 10 meters, wherein preferably the tubular impact weight has a wall thickness between 10 and 20 centimeters.

[0043] In an embodiment, the lifting tool is configured to provide a vertical distance between the anvil surface and the initial height of the impact weight of at most 2 meters, such as approximately 1 meter.

[0044] In an embodiment, the pile driving device has a housing extending coaxially about a tubular impact weight, the housing having an open lower end that rests on a driving head assembly.

[0045] Preferably, the housing is peripherally closed.

[0046] In a practical embodiment, the housing has an open top end and has a central passage having a diameter corresponding to at least 50%, more preferably at least 75%, of the inner diameter of the top portion of the pile.

[0047] In a practical embodiment, the lifting mechanism comprises a plurality of hydraulic lifting cylinders.

[0048] In an embodiment, for example generally as disclosed in US4601349, the lifting cylinder is integrated with an acceleration mechanism that accelerates the falling counterweight downwardly at an acceleration greater than 1G (for example adjustable between 1G and 2G).

[0049] Preferably, the hydraulic lifting cylinders are arranged in a circular array above the tubular impact weights, more preferably so as to leave a central passage having a diameter corresponding to at least 50%, more preferably at least 75% of the inner diameter of the top portion of the pile.

[0050] In practical embodiments, the quick-release system includes one or more quick-release valves that are opened to allow rapid discharge of hydraulic fluid from the lift cylinders. For example, the lift cylinders may be connected to a common hydraulic discharge conduit assembly controlled by a single quick-release valve, or two groups of lift cylinders may each be connected to a corresponding common hydraulic discharge conduit assembly, each controlled by a corresponding quick-release valve. These measures can reduce any lag in the discharge of hydraulic fluid from one or more lift cylinders relative to one or more other lift cylinders.

[0051] For example, a plurality of hydraulic lifting cylinders are arranged on a top portion of the housing, for example on an inwardly facing flange of the housing.

[0052] In an embodiment, the vertical guide structure comprises an impact weight engagement member configured to engage the tubular impact weight, for example on an outer side of the tubular impact weight, wherein preferably the impact weight engagement member is configured to engage the impact weight with a preload.

[0053] In a practical embodiment, the vertical guide structure includes roller assemblies, each of which includes one or more horizontal-axis rollers that engage the tubular impact weight, for example, on its outer side. For example, the roller assemblies are mounted to the housing. For example, there is a lower set of roller assemblies and an upper set of roller assemblies, and the vertically movable impact weight is always guided by these lower and upper sets of roller assemblies.

[0054] In an embodiment, the roller assembly is configured to press one or more rollers against the tubular impact weight with a preload. This allows, for example, precise vertical guidance and / or absorption of peak loads caused by rebound of the impact weight.

[0055] In an embodiment, the driving head assembly includes a resilient material buffer member, such as an annular resilient material buffer member, disposed between the anvil surface and the contact surface.

[0056] In an embodiment, the energy transfer assembly of the driving assembly includes one or more spring devices and / or one or more damper devices acting between the anvil surface and the contact surface. The one or more spring devices and / or one or more damper devices are configured to extend the duration of energy transfer, which improves efficiency and reduces noise generation.

[0057] In an embodiment, the driving head assembly comprises a plurality of spring devices and / or a plurality of damper devices arranged in a circular array in the driving head assembly, for example implemented as an integrated spring and damper device.

[0058] In an embodiment, the driving assembly includes a plurality of cylinder devices arranged in an annular array in the driving assembly, each cylinder device having a cylinder body, a piston and a chamber defined by the piston, wherein the chamber is filled with a liquid and / or a gas, such as oil, and wherein, optionally, the chambers of the cylinder devices are interconnected.

[0059] In an embodiment, a plurality of cylinder devices are arranged in a circular array in the driving head assembly, wherein the cylinder devices are arranged between an annular anvil member forming an anvil surface and a base member forming a contact surface. The cylinder devices are made of metal, such as steel or titanium.

[0060] In an embodiment, a plurality of cylinder devices are evenly arranged along the circumference of the pile and on the top flange of the pile, wherein each cylinder device is provided with an anvil member at its top end and a bottom member forming a contact surface between the cylinder device and the top flange of the pile.

[0061] In an embodiment, the cylinder device comprises a cylinder body, a piston and a single chamber defined by the cylinder body and the piston. Preferably, the chamber is filled with a liquid, and oil is preferably used to fill the chamber due to its relatively high elasticity (eg compared to water).

[0062] Preferably, the piston is embodied as a hollow piston. The piston has a central chamber extending from an opening at the piston's bottom end to a closed end at the piston's top end. The central chamber is defined by an annular piston wall and the piston's top wall. The central chamber forms part of a single chamber. By using a hollow piston, the piston's weight is reduced and the volume of liquid, such as oil, is increased. This results in improved energy transfer efficiency.

[0063] In one embodiment, the bottom end of the piston wall is chamfered. During pile hammering, the piston moves very quickly through the oil as the oil is compressed. This can create cavitation areas near the bottom end of the piston wall, which degrades the oil and reduces the efficiency of energy transfer. By using a chamfered bottom end of the piston wall, the piston can move more easily through the oil, i.e., the piston wall is more fluid, which reduces the chance of cavitation areas forming in the oil.

[0064] In one embodiment, an elastically compressible element is disposed on top of the top end of the piston. This element is implemented to act as a cushion, such as a plate or disk made of an elastically compressible material, or a metal element, such as one or more coil springs. By providing this element on the top of the piston so as to act between the piston and the impact weight, the piston accelerates more slowly than if this element were not present.

[0065] In an embodiment, the pile driving device comprises a sleeve extending downwardly from the head end assembly along a top section of the pile.

[0066] In an embodiment, the pile driving device is connected to a lifting tool of a crane during pile driving, wherein a plurality of shock absorbers are mounted to a top of the pile driving device, e.g. to a housing of the pile driving device, the plurality of shock absorbers are connected to a spreader structure at top ends of the shock absorbers, e.g. two shock absorbers are connected to a spreader rod, and wherein the spreader structure is connected to the lifting tool, e.g. via two slings.

[0067] In an embodiment, the method is performed offshore, for example for installation of monolithic piles, using a vessel comprising a pile gripping device, such as a motion compensating pile gripper, which is operated to hold the pile upright during driving.

[0068] In an embodiment, a vibrating device is used in conjunction with a pile driving device.

[0069] For example, the vibration device is configured for generating an alternating force about a vertical axis of the pile at a vibration frequency so as to vibrate the pile about the axis and reduce friction between the pile and soil (eg seabed).

[0070] For example, the vibration device is configured to generate vertical vibrations to drive the pile into the soil. In an embodiment, this can be combined with the vibration of the pile around a vertical axis to reduce friction between the pile and the soil (e.g., seabed).

[0071] For example, the vibration device is mechanically decoupled from the pile driving device described herein, so that the vibration device is not affected, or is affected in a limited manner, by the impacts caused by the impact weight.

[0072] For example, the vibration device is configured to be mounted within a top portion of the pile, e.g., before the pile driving device is placed on the pile. When present, the central passage of the pile driving device may provide access to the vibration device, e.g., to allow for supplying energy to the vibration device, e.g., a hydraulic line for supplying hydraulic fluid to a motor of the vibration device.

[0073] For example, the vibration device is supported by a floating support member configured to allow the vibrator to float along a vertical axis to prevent an impact applied by the pile driving device from being directly transmitted to the vibrator. For example, the floating support member is configured to cushion the impact force, for example, one or more elastic bodies, such as one or more springs or cylinders, are provided to support the vibrator in the vertical direction.

[0074] For example, the vibration device is connected to an inward flange of the pile and / or is clamped inside the top part of the pile, for example using hydraulic friction clamps (such as wedge clamps).

[0075] For example, the vibration device is only connected to the pile when the pile driving device is not applying an impact to the pile. This avoids excessive mechanical loads on the vibration device.

[0076] For example, a vibration device is used for the first stage of driving the pile into the soil, while a pile driving device with an impact weight is used for the second stage of driving the pile into the soil. This can, for example, reduce the overall noise generation of the installation of a (single) pile.

[0077] For example, the vibrating device is independently suspended and therefore not mechanically attached to the pile driving device. For example, the vibrating device is suspended from a crane, such as the same crane from which the pile driving device is suspended, for example via the aforementioned shock absorbers and possibly a spreader structure. Alternatively, as described herein, the vibrating device is suspended from the spreader structure, for example via a winch arrangement.

[0078] In an embodiment, the lower portion of the impact weight comprises one or more spring devices and / or one or more damper devices in contact with the anvil surface.

[0079] In one embodiment, the impact weight includes holes extending from a lower portion of the impact weight in the height direction of the impact weight, wherein the holes are distributed along the circumference of the impact weight. The length of the holes is between 50-90% of the impact weight height, preferably between 60-80% of the impact weight height. An elongated member, such as a rod or bar, is housed within the hole and extends along the entire length of the hole, such that the lower end of the elongated member extends beyond the lower portion of the impact weight and contacts the anvil surface. Due to the length of the elongated member, it acts like a spring, which allows for a longer duration of energy transfer, thereby increasing efficiency and reducing noise generation. For example, the elongated member is housed in the hole with some play.

[0080] The size, shape, and material of the impact weight make it difficult to manufacture the impact weight from just one part. To make the manufacturing process of the impact weight easier and faster, the impact weight can be made from multiple parts that are then joined to form the impact weight.

[0081] In an embodiment, the impact weight comprises two or more ring members, e.g., each ring member is made of steel, e.g., cast steel or welded steel, which are stacked on top of each other to form the impact weight. In an embodiment, each ring member of the impact weight comprises two or more ring segments, e.g., semicircular ring segments, e.g., more than four ring segments, which together constitute the ring member.

[0082] In an embodiment, a plurality of ring members, such as ring segments thereof, are vertically connected to each other using vertical fasteners, such as bolts.

[0083] In an embodiment, the impact weight includes two or more ring members stacked on top of each other, wherein each ring member includes two or more ring segments, wherein the ring segments of adjacent ring members are circumferentially offset such that each ring segment overlaps at least two adjacent ring segments. Vertical fasteners, such as long bolts, can extend through aligned holes in the ring segments to interconnect the ring segments and the ring members, thereby forming a tubular impact weight.

[0084] In an embodiment, adjacent ring segments are welded to one another to form a ring member, wherein the plurality of ring members are interconnected by vertical fasteners extending through aligned holes in the ring members.

[0085] When the impact weight falls and contacts the anvil of the driving assembly, it will expand in the radial direction, for example in its lower portion, which causes significant tangential stresses in the impact weight. These repeated tangential stresses acting on the impact weight can cause fatigue, which can lead to damage and failure. To reduce the tangential stresses, the impact weight can be implemented so that the impact weight has multiple regions that provide flexibility in the tangential direction. The tangential flexibility of these regions allows the impact weight to expand more freely when in contact with the anvil, which reduces the peak tangential stresses. To achieve these tangentially flexible regions, multiple embodiments of the impact weight are contemplated.

[0086] In an embodiment, the impact weight comprises two or more ring segments, such as circular arc segments or quadrilateral segments, wherein adjacent segments are connected to each other by an elastic region, which can also be referred to as a spring region. The elastic region can bridge the gap between adjacent ring segments, which are, for example, embodied as folded steel parts.

[0087] In an embodiment, the impact counterweight includes one or more ring members, each ring member being assembled from two or more ring segments, such as arc segments or quadrilateral segments, wherein the ring segments have an inner wall surface, an outer wall surface and a wall thickness, wherein adjacent ring segments are connected to each other by welds, such as vertical welds, wherein the welds in the ring members extend alternately from the inner wall surface and the outer wall surface, and wherein each weld extends only partially between the inner wall surface and the outer wall surface, so that the groove extends at the junction of the ring segments.

[0088] The tangential stresses caused by a falling impact weight can cause structural damage, particularly in the falling weight's circumferential welds, which are typically less resistant to stress and fatigue than the rest of the impact weight. To reduce the stresses acting on the circumferential welds, the impact weight includes multiple quadrilateral segments that form a polygonal shape. This reduces the stress on the circumferential welds by positioning them further away from high-stress areas.

[0089] For example, the segments are implemented as quadrilateral segments, so that two or more segments form a polygon, for example a hexadecagon comprising 16 quadrilateral segments.

[0090] In an embodiment, the impact weight comprises a single circular segment having an inner wall surface and an outer wall surface.For example, the single circular segment has axial grooves evenly distributed along the radius and height of the impact weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] The present invention will now be explained with reference to the accompanying drawings. In the drawings:

[0092] Figure 1A Shown in vertical section is a monolithic pile and a portion of a pile driving device according to a first embodiment of the invention;

[0093] Figure 1B Shown on a larger scale Figure 1A part of

[0094] Figure 2 is a top view of the device of Figure 1,

[0095] Figure 3 It is a tubular impact weight of the pile driving device in Figure 1.

[0096] Figure 4 It is the outer shell of the pile driving device in Figure 1,

[0097] Figure 5 It is the head end assembly of the pile driving device in Figure 1,

[0098] Figures 6a and 6b are roller assemblies of the pile driving device of Figure 1.

[0099] Figure 7 shows the handling of the pile driving device of FIG1 by a crane,

[0100] FIG8a shows another embodiment of the head end assembly,

[0101] FIG8b shows an embodiment of a cylinder arrangement,

[0102] Figure 9 A single pile and part of the pile driving device are shown in vertical section, including the head end assembly of FIG. 8 a .

[0103] Figure 10 Schematically shows the application of the vibration device,

[0104] Figures 11a-11f show an alternative embodiment of a tubular impact weight,

[0105] FIG12a shows an embodiment of a pile travel prevention member comprising a damping member, and

[0106] Figure 12b shows an embodiment of a pile travel preventing member implemented as a cable having a first end and a second end. DETAILED DESCRIPTION

[0107] refer to Figure 1A-Figure 7 , a first embodiment of the invention will be described. The accompanying drawings are drawn to scale and show a monolithic pile 1 having an external diameter of 8 metres being driven into the seabed. Figure 1A The people shown in FIG. 1 are shown only as a reference to enable understanding of the dimensions of the components shown by way of example.

[0108] The monolithic pile 1 is a large diameter hollow and open-ended steel monolithic pile 1 that is driven vertically into the seabed to serve as a foundation for an offshore wind turbine.

[0109] The pile can have a constant diameter over its length, but other designs are also possible. For example, a single pile can have a lower portion with a first maximum diameter, a tapered portion, and a top portion 1a with a second minimum diameter. For example, the second minimum dimension can be at least 5 meters, such as 8 meters, as shown here.

[0110] The monolithic pile 1 has a cylindrical top portion 1a having a top wall thickness between the inner diameter and the outer diameter. For example, as shown here, the wall thickness of the top portion 1a is 8 cm. The top portion is open at its top end.

[0111] Considering the connection of a wind turbine tower to the monolithic pile 1 , the pile 1 has an inwardly facing top flange 1 b where bolt holes are provided.

[0112] As is known in the art, the length of a single pile can be between 60 and 120 meters. Base diameters between 8 and 12 meters are known or proposed. The weight of a single pile can be well over 1,000 tons, for example between 2,000 and 3,000 tons. Wall thicknesses between 8 and 15 centimeters are known or proposed.

[0113] Figure 1- Figure 7 A pile driving device 10 is shown which is configured to be arranged on the top end of the pile 1 .

[0114] The pile driving device 10 comprises:

[0115] a driving head assembly 20 having an annular contact surface 21 configured to rest on the top end of the pile 1 and an annular anvil surface 22 above the annular contact surface 21,

[0116] a steel impact weight 30 , which in the example depicted has a mass of approximately 200 tons, which is vertically movable above the annular anvil surface 22 of the driving head assembly 20 ,

[0117] a vertical guide structure 40 configured to vertically guide the impact weight 30 ,

[0118] The driving assembly 20 is configured to transfer energy between the annular anvil surface 22 and the annular contact surface 21, and is used to transfer energy from the impact weight 30 to the annular contact surface 21 and thereby to the pile top 1a.

[0119] a lifting system 60 configured to bring the impact weight 30 to an initial height position relative to the annular anvil surface 22 of the driving head assembly 20 ,

[0120] A quick release system 70 adapted to enable quick release of the lifting system 60 , so that the impact weight 30 falls from the initial height position onto the anvil surface 22 of the driving head assembly 20 .

[0121] The pile driving device 10 is operable in a repetitive cycle wherein:

[0122] - lifting the impact weight 30 to the initial height position through the lifting system 60,

[0123] - Operating the quick release mechanism 70 to achieve a quick release of the lifting system 60, causing the impact weight 30 to fall from the initial height position onto the anvil surface 22 of the driving head assembly 20, wherein the energy from the falling impact weight 30 is transferred to the contact surface 21 of the driving head assembly and thereby to the top end of the pile, causing the pile to be driven deeper into the soil.

[0124] As shown in the figure, the impact weight 30 is implemented as a tubular impact weight made of steel. The tubular impact weight is hollow and open at the ends.

[0125] The wall thickness of the tubular impact weight 30 is on average slightly greater than the wall thickness of the cylindrical wall of the top portion 1 a of the monolithic pile 1 in order to obtain the required weight of the impact weight 30 .

[0126] The height of the tubular impact weight 30 is greater than 4 meters, for example between 4 and 12 meters, for example between 6 and 10 meters. In the depicted embodiment, for a monolithic pile with a top diameter of 8 meters and an impact weight diameter of 8 meters, the height is approximately 7.5 meters.

[0127] The diameter of the tubular impact weight 30 generally corresponds to the diameter of the monolithic pile top part 1 a so that the mass of the impact weight 30 is generally located in vertical projection on the cylindrical wall of the top part 1 a. This allows for optimal energy transfer.

[0128] The tubular impact weight has a diameter such that in vertical projection it overlaps the wall thickness of the top portion 1a of the pile 1. The wall thickness of the tubular impact weight is between 10 cm and 20 cm.

[0129] As shown here, the contact surface 21 is located directly above the top part wall 1 a of the monolithic pile 1 in order to avoid that the top flange 1 b is over-tensioned during driving of the pile.

[0130] As shown, the driving assembly 20 is configured to expose a peripheral portion of the inwardly facing top flange 1 b, for example so that the bolt holes remain accessible. In an embodiment, this arrangement may allow the flange 1 b to be gripped by a gripper of a monolithic pile lifting tool.

[0131] The lifting tool 60 is configured to provide a vertical distance of up to 2 meters, here a maximum of about 1 meter, between the anvil face 22 and the initial height of the impact weight 30. The lifting tool 60 is configured to adjust the initial height to adjust the energy per strike of the impact weight, for example, to a maximum height of 1 meter.

[0132] The pile driving device has a housing 50 extending coaxially around the tubular impact weight 30. The housing has an open lower end, which rests on the driving head assembly 20.

[0133] The housing 50 is made of steel, such as welded steel.

[0134] The housing 50 has an open top end. Optionally, a (removable) movable closure is associated with the open top end of the housing 50, such as a removable cover.

[0135] The housing 50 is closed at its perimeter, for example to form a noise barrier. For example, a sound deadening lining material, not shown, is present on the sides of the housing to reduce noise emanating from the housing 50 when pile driving occurs.

[0136] The housing 50 has an open top end and has a central passage with a diameter corresponding to at least 50%, more preferably at least 75%, of the inner diameter of the top portion of the pile.

[0137] The pile driving device has an integrated lifting and acceleration mechanism 60 comprising a plurality of integrated lifting and accelerator devices 61. These devices are distributed in a circular array, for example, on the top portion of the housing 50, where they are mounted on the inward-facing top flange 51 of the housing 50. For example, six to twelve devices 61 are present on the housing 50. For example, device 2 allows for adjustable acceleration of the falling counterweight up to 2 G. Greater accelerations are not excluded, but would require a heavier design of the pile driving device, for example, its housing 50.

[0138] The device 61 is vertically mounted on the housing 50 .

[0139] The devices 61 are each connected to the upper portion of the tubular impact weight 30 .

[0140] The device 61 has a piston and a piston rod 62 extending downwardly from a cylinder 63 attached to the housing 50. The piston rod 62 has an end connected to the upper section of a tubular impact weight.

[0141] In this example, the impact weight 30 has a hole 31 along its upper edge, wherein a clevis of the piston rod fits over the upper edge and is connected to the impact weight 30 via a pin.

[0142] The lower chamber 64 defined by the piston is a hydraulic lift chamber. The upper chamber 65 defined by the piston is a pressurized acceleration chamber, for example, filled with pressurized gas, such as from a gas buffer 66. For example, as is known in the art, a gas pressure regulating valve assembly is provided that allows the desired gas pressure and thereby the desired acceleration of the impact weight 30 to be set.

[0143] The chambers 64 of the device 61 may be connected to a common conduit arrangement 67 for supplying hydraulic liquid to the chambers 64 and / or for quickly draining hydraulic liquid, such as water, from the chambers 64. For example, the common conduit for a plurality of chambers 64, possibly all of the chambers 64, is connected to one or more quick-release valves 70 that open to allow rapid draining of hydraulic liquid from the lifting chambers 64 of the device 61. A hydraulic system is provided, for example including one or more hydraulic pumps 68, for use in the lifting operation.

[0144] In another embodiment, the quick release device is implemented in the form of an operable connector device that connects the lift cylinder to the impact weight, such as a mechanical latch, magnetic connector, friction clamp, etc.

[0145] To ensure that the impact weight 30 drops accurately in the vertical direction onto the anvil surface, the vertical guide structure 40 includes roller assemblies 41, 42 mounted on a housing 50. Each roller assembly 41, 42 includes horizontal axis rollers 43, here two per assembly, which engage the tubular impact weight, here the outer peripheral side of the tubular impact weight.

[0146] These assemblies 41, 42 are configured to press one or more rollers 43 against the tubular impact weight 30 with a preload. This is achieved by a biasing assembly 44 in each roller assembly.

[0147] The roller 43 is shown having an outer lining of elastomeric material which engages the outer side of the steel impact weight 30 .

[0148] like Figure 1A As best shown in FIG. 1 , the driving head assembly 20 includes a resilient material buffer member 23 , here an annular resilient material buffer member, disposed between the anvil face and the contact face.

[0149] The driving head assembly 20 is shown to be composed of a metal ring member 24, the bottom side of which defines a contact surface 21. A groove with an open top is formed in the metal ring member 24, and an annular buffer member 23 is received in the groove.

[0150] The anvil surface 22 is shown to be formed by a metal anvil ring resting on an annular cushioning member 23 .

[0151] Cushioning member 23 is shown having a thickness approximately equal to the thickness of impact weight 30 and a height at least equal to the thickness of member 23 .

[0152] For example, a cooling device is provided for the annular buffer member 23, such as using a water spray, a liquid cooling pipe in the head end assembly, etc.

[0153] For example, the cushioning member 23 is composed of stacked layers of metal and synthetic materials, such as metal, which facilitates removal of heat from the cushioning member 23 .

[0154] For example, the cushioning member 23 is composed of metal elements, such as fibers, embedded in a synthetic material, such as metal members that facilitate removal of heat from the cushioning member 23 .

[0155] For example, as shown, the annular cushioning member 23 has vertical sides that are taller than the thickness of the cushioning member, which facilitates removing heat from the cushioning member.

[0156] Removing heat from the cushioning member may serve to extend the useful life of the member 23 .

[0157] The pile driving device 1 is shown to include a sleeve 80 extending downwardly from the head end assembly 20 along the top 1 a of the pile 1 .

[0158] As shown, the entire pile driving device 10 is embodied so as to enable access to the interior of the monolithic pile 1 even during pile driving. A central passage 90 effectively extends from above through the lower end of the device 10 and has a diameter of at least 2 meters, preferably at least 50% of the diameter of the pile 1, more preferably at least 75% of the diameter of the pile 1.

[0159] For example, as shown, the diameter of the passage 90 corresponds at least to the diameter of the opening defined by the inwardly facing flange 1 b of the post.

[0160] Preferably, the flange 1 b remains accessible via this passage 90 .

[0161] Due to the relatively large cross-section of central passage 90, here exceeding 75% of the diameter of the monolithic pile, other equipment can be used during pile driving, such as a jetting system, which requires a relatively large high-pressure jetting line to enter the interior of the monolithic pile 1 through passage 90. The housing 50 can be configured to provide support for such additional equipment. Furthermore, in embodiments, flange 1b can be used to provide support for additional equipment involved in pile driving, such as jetting equipment, vibrating equipment, etc.

[0162] A relatively large passage 90 is also beneficial when the pile driving device 10 is stored, for example, on the deck of a vessel, for example to allow a hydraulic power unit associated with the pile driving device 10 to be placed within the passage 90 in a stored arrangement.

[0163] like Figure 7 As best shown in FIG, the pile driving device 1 can be configured to be connected to a lifting tool of a crane during pile driving. A shock absorber 90 is mounted on the top of the pile driving device, in this case on the housing 50 of the pile driving device. A plurality of shock absorbers are connected at their top ends to a spreader structure 100, in this case two shock absorbers connected to a spreader bar. The spreader structure is connected to the lifting tool, such as a crane hook, via two slings 101.

[0164] Refer to Figure 8 and Figure 9 , different versions of the pile driving device and method of the present invention will be discussed. Figure 7 Components corresponding to those shown in FIG. 1 are denoted by the same reference numerals.

[0165] FIG8 shows a head end assembly 20'. The assembly 20' has a plurality of cylinder devices 200 arranged in a circular array within the driving assembly 20'. For example, there may be between 20 and 60 cylinder devices 200 within the assembly 20'. For the 8-meter diameter pile driving apparatus shown, this number may be approximately 40.

[0166] The cylinder device 200 is arranged between an annular anvil member 210 forming the anvil surface 22 and a base member 215 forming the contact surface 21 .

[0167] Each cylinder assembly has a cylinder body 201, where all cylinders are integrated into a steel annular head body 202 that forms the entire cylinder body. Each cylinder assembly 201 has a single-acting piston and piston rod assembly 203 and a chamber 204 defined by the piston. In this example, the chambers 204 are all completely filled with a liquid, such as water. The volume of the liquid is preferably adjustable. In an embodiment, all chambers 204 are interconnected.

[0168] For example, each piston of device 200 has a diameter between 20 cm and 50 cm.

[0169] The multi-cylinder device 200 having a chamber filled with a liquid, such as water, effectively acts as a spring for impacting the impact weight 30 onto the anvil surface 22. The liquid pressure can rise to significant values, such as over 400 bar, for example approximately 600 bar.

[0170] In the embodiment schematically shown in Figure 8b, the cylinder device comprises a cylinder body 203b, a piston 203a and a single chamber 203c defined by the cylinder body 203b and the piston 203a. The chamber 203c is filled with a liquid, such as oil.

[0171] The piston 203a is implemented as a hollow piston. The hollow piston has a central cavity extending from an opening at the bottom end of the piston, wherein the central cavity is defined by an annular downwardly extending piston wall 203d. The central cavity forms part of a single chamber.

[0172] The bottom end of the piston wall 203d is preferably chamfered.

[0173] An elastic element 203e, such as a solid compressible material element and / or a metal elastic element, is arranged on top of the top end of the piston 203a.

[0174] In an embodiment, considering the huge maximum pressure that occurs in chamber 204, liquid can be allowed to leak along the piston and piston rod assembly, rather than attempting to prevent leakage by a complicated sealing device. Here, it is envisioned that a supplementary circuit for liquid (e.g., water) to chamber 204 is provided, which supplies liquid to chamber 204 in order to compensate for leakage. For example, it is envisioned that the leakage amount of each impact each chamber 204 is approximately 1 liter. Particularly when the liquid is water, from an environmental perspective, leakage is not annoying. If the liquid is oil, preferably due to its elasticity, the leaked oil will be collected, for example, collected via one or more grooves, and supplied to the supplementary circuit.

[0175] In an embodiment, there is no annular anvil member 210 so that the entirety of the piston top forms an annular anvil surface onto which the steel impact weight 30 rests.

[0176] In an embodiment, the cylinder device 200 is arranged at the lower end of the impact counterweight 30, and preferably the piston of each device 200 extends downward. Here, for example, the impact counterweight 30 is implemented as a single tubular ring segment, or the impact counterweight 30 includes a plurality of ring segments 32, wherein one or more cylinder devices 200 are arranged at the lower end of each ring segment 32.

[0177] exist Figure 7 , the housing 50 is also shown resting on top of the head end assembly 20 ′, thus effectively resting on a component that is integral with or formed from the annular anvil member 210 .

[0178] The sleeve 80 extends downwardly from the housing 50 , surrounds the head end assembly 20 ″ and extends downwardly along the upper portion 1 a of the monolithic pile 1 .

[0179] Under the impact of the impact weight 30, the head end assembly 20 ' uses some spring action to transfer the impact to the cylindrical wall at the top end of the monolithic pile. As shown, in the embodiment, the contact surface 22 is arranged vertically above the cylindrical wall so that energy is transferred vertically from the impact weight 30 into the wall without excessive loading of the flange 1b.

[0180] In the embodiment, Figure 10 As shown in , the system further includes a vibration device 300.

[0181] Figure 10 The vibrating device 300 is shown to be independently suspended and therefore not mechanically attached to the pile driving device 10 .

[0182] Preferably, the channel 90 is sized so that the device 300 can be moved through the channel 90 , for example for removal of the device 10 without the need to remove the device 10 from the pile 1 .

[0183] Preferably, the vibration device has a clamping mechanism operable to clamp the device 300 to the pile 1 , for example using hydraulically operated clamps 306 that create a friction fit with the interior of the pile 1 .

[0184] As is known in the art, one or more rotating eccentric mass units 307 induce the desired vibrations.

[0185] The vibration device 300 is mechanically separated from the pile driving device 10 and can also be selectively disconnected from the pile 1 , so that the vibration device 300 is not affected by the impact caused by the impact weight 30 or is affected in a limited manner.

[0186] Figure 10 The vibrating device 300 is shown suspended from a crane, here for example via cables 301. The pile driving device is suspended from the same crane, for example via the described shock absorbers 90 and possibly a spreader structure 100.

[0187] Optionally, the vibrating device 300 is suspended from the spreader structure 100, for example via a winch arrangement.

[0188] For example, the vibration device 300 is configured to generate an alternating force about a vertical axis of the pile at a vibration frequency so as to vibrate the pile about the axis and reduce friction between the pile and soil (eg, seabed).

[0189] For example, the vibration device 300 is configured to generate vertical vibrations to drive the pile into the soil. In an embodiment, this can be combined with the vibration of the pile around a vertical axis to reduce friction between the pile and the soil (e.g., seabed).

[0190] The central channel of the pile driving device also provides access to the vibration device, eg allowing for supplying energy to the vibration device, eg hydraulic lines for supplying hydraulic fluid to the motor of the vibration device.

[0191] For example, the vibration device 300 is only connected to the pile 1 when the pile driving device 10 is not applying an impact to the pile. This avoids excessive mechanical loads on the vibration device.

[0192] For example, the vibration device 300 is used for the first stage of driving the pile into the soil, while the pile driving device 10 with the impact weight 30 is used for the second stage of driving the pile 1 into the soil. This can, for example, reduce the overall noise generation of the installation of a (single) pile.

[0193] FIG11 a shows a longitudinal cross-section of an embodiment of an impact weight 30, wherein the impact weight comprises five ring members 30a-30e stacked one on top of the other to form the impact weight 30. Each ring member 30a-30e comprises a plurality of ring segments 32. The ring segments 32 of adjacent ring members 30a-30e are not vertically aligned, such that a ring segment overlaps at least two vertically adjacent ring segments. Vertical fasteners 33, such as bolts, are used to connect adjacent ring members and adjacent ring segments to each other.

[0194] FIG11 b shows a cross-section of an impact weight 30, wherein the ring segments 32 are each semicircular, forming a ring member of a tubular impact weight. Each ring segment is provided with a plurality (here, three) of holes 34. When the ring members are stacked on top of each other, the holes 34 align, and vertical fasteners 33 can be inserted through the aligned holes. For example, fasteners 33 are long bolts.

[0195] FIG. 11 c shows an alternative embodiment of an impact weight 30, wherein the impact weight 30 comprises three ring segments 32 connected to one another using elastic regions 35 or spring regions 35 that bridge the small distances between adjacent ring segments 32. For example, the elastic regions 35 are implemented as steel components, such as welded components, for example with folded sections, an example of which is shown here. Each elastic region 35 is shown with an inwardly folded section, but other configurations are also conceivable.

[0196] FIG11 d shows an alternative embodiment of an impact counterweight 30, wherein the impact counterweight 30 comprises a plurality of ring segments 32. The ring segments have an inner wall surface and an outer wall surface and a wall thickness. Adjacent ring segments are connected to each other by welding, in this case vertical welds. The welds extend alternately from the inner wall surface and the outer wall surface. Each weld does not extend through the wall thickness of the ring segment, but only partially extends between the inner wall surface and the outer wall surface. As a result, alternating vertical grooves are formed. As explained, this alternating arrangement of the partial welds reduces the tangential peak stress in the impact counterweight.

[0197] FIG. 11 e shows an alternative embodiment of an impact weight 30 , wherein the impact weight is provided with evenly distributed axial grooves 37 , which are divided in the tangential direction.

[0198] FIG11 f shows an embodiment of an impact counterweight 30 in which the impact counterweight comprises sixteen segments 32, each of which is implemented as a quadrilateral segment so that the connected segment segments 32 form a hexagon. Here, the segment segments are welded to each other, but other arrangements (as discussed herein) are also possible. A 16-sided polygonal cross section can be considered an approximation of a circular design. In another embodiment, taking into account the diameter of the counterweight 30, a 32-sided polygonal cross section, for example, is also feasible.

[0199] Figure 11g shows a cross-section of an alternative embodiment of an impact weight 30, wherein the impact weight 30 includes holes 38 extending from a lower portion of the impact weight 30 in the height direction of the impact weight, wherein the holes are distributed along the circumference of the impact weight 30. The length of the holes is between 50-90% of the height of the impact weight, preferably between 60-80% of the height of the impact weight. A slender member 39, for example made of steel, such as a solid steel rod, is housed inside the hole and extends along the entire length of the hole, so that the lower end of the slender member 39 extends beyond the lower portion of the impact weight and contacts the anvil surface. It is conceivable that the slender members 39 act as axial springs, for example having radial play in the corresponding holes. In an embodiment, as shown, each slender member 39 can have a foot configured to be able to contact the anvil surface.

[0200] Figure 12a shows a pile travel preventing member 400 comprising a damping member 401 suspended from a pile driver or alternatively from a crane. An engaging member 402 is suspended from the damping member 401 and engages the inwardly facing top flange 1 b of the pile 1 .

[0201] FIG12 b shows an alternative embodiment of a pile travel preventing member 400, wherein the pile travel preventing member is implemented as a cable 403 having a first end and a second end, wherein the first end is suspended from the pile driver, and wherein the second end is provided with an engagement member 402 configured to engage the inwardly facing top flange of the pile 1 b. As shown, during pile driving, the cable 403 is slack.

Claims

1. A pile driving method for vertically driving a large diameter hollow open-ended steel pile into soil, the pile having a cylindrical top portion with a top portion wall thickness between an inner diameter and an outer diameter, wherein the outer diameter is at least 5 meters, the pile being, for example, a monolithic pile of an offshore wind turbine, the soil being, for example, the seabed. in, A pile driving device is used which is arranged on the top end of the pile, the pile driving device comprising: a driving assembly having an annular contact surface resting on the top end of the pile and an annular anvil surface above the annular contact surface, a steel impact weight having a mass of at least 100 tons, for example greater than 200 tons, said impact weight being vertically movable above the anvil surface of the driving head assembly, - a vertical guide structure configured to guide the impact weight vertically, wherein the driving head assembly is configured for energy transfer between the anvil surface and the contact surface for transferring energy from the falling impact weight to the annular contact surface and thereby to the pile top, - a lifting system configured to bring the impact weight into an initial height position relative to the anvil surface of the driving head assembly, - a quick release system adapted to achieve a quick release of the lifting system so that the impact weight falls from said initial height position onto the anvil surface of the driving assembly, Wherein, the method comprises repeating cycles wherein: -The impact counterweight is lifted to the initial height position through the lifting system, - operating the quick release mechanism to achieve a quick release of the lifting system, causing the impact weight to fall from the initial height position onto the anvil surface of the driving head assembly, wherein energy from the falling impact weight is transferred to the contact surface of the driving head assembly and thereby to the top end of the pile, causing the pile to be driven deeper into the soil, The impact weight comprises, preferably, a tubular impact weight made of steel, for example with a wall thickness between 10 cm and 20 cm.

2. The pile driving method according to claim 1, wherein: The impact weight is embodied as a tubular impact weight made of steel, for example with a wall thickness between 10 cm and 20 cm, wherein the tubular impact weight has a height between 4 m and 12 m, for example between 6 m and 10 m.

3. The pile driving method according to claim 1 or 2, wherein: The tubular impact weight has a diameter such that in vertical projection the tubular impact weight overlaps the wall thickness of the top portion of the pile.

4. Pile driving method according to one or more of the preceding claims, wherein: A plurality of accelerator devices are provided in the pile driving device. The plurality of accelerator devices are arranged in a circular array and engaged with the tubular impact weight at distributed positions.

5. Pile driving method according to one or more of the preceding claims, wherein: The pile driving device is configured such that the tubular impact weight falls only under the force of gravity (1G), for example, the pile driving device does not have one or more accelerator devices for the impact weight.

6. Pile driving method according to one or more of the preceding claims, wherein: The tubular impact weight is hollow and open ended, for example wherein the tubular impact weight has a central passageway having a diameter of at least 2 metres, for example at least 50% or at least 75% of the inner diameter of the top portion of the pile.

7. Pile driving method according to one or more of the preceding claims, wherein: The pile has an inwardly facing top flange, e.g. with bolt holes, and wherein the heading assembly is configured to expose a portion of the inwardly facing top flange, e.g. wherein the heading assembly has an inner diameter that is larger than an inner diameter of the inwardly facing top flange, such that a peripheral portion of the flange is exposed, e.g. to allow gripping of the flange by a gripper of a pile lifting tool.

8. Pile driving method according to one or more of the preceding claims, wherein: The tubular impact weight has a wall thickness between 10 cm and 20 cm.

9. Pile driving method according to one or more of the preceding claims, wherein: The lifting tool is configured to provide a vertical distance of at most 2 meters, such as approximately 1 meter, between the anvil surface and the initial height of the impact weight.

10. Pile driving method according to one or more of the preceding claims, wherein: The pile driving device has a housing extending coaxially around a tubular impact weight, the housing having an open lower end resting on a driving head assembly, and wherein, preferably, the housing is peripherally closed.

11. Pile driving method according to one or more of the preceding claims, wherein: The lifting mechanism comprises a plurality of hydraulic lifting cylinders, and wherein, preferably, the quick release system comprises one or more quick release valves that open to allow rapid discharge of hydraulic fluid from the lifting cylinders.

12. Pile driving method according to one or more of the preceding claims, wherein: The vertical guide structure includes roller assemblies, each roller assembly including one or more horizontal-axis rollers engaging a tubular impact weight, and wherein the roller assembly is configured to press the one or more rollers against the tubular impact weight with a preload.

13. Pile driving method according to one or more of the preceding claims, wherein: The pile driving device is connected to a lifting tool of a crane during pile driving, wherein a plurality of shock absorbers are mounted to a top portion of the pile driving device, for example a housing of the pile driving device, the plurality of shock absorbers are connected to a spreader structure at their top ends, for example two shock absorbers are connected to a spreader rod, and wherein the spreader structure is connected to the lifting tool, for example via two slings.

14. Pile driving method according to one or more of the preceding claims, wherein: The method is performed at sea, for example for the installation of a monolithic pile, and wherein a vessel is used comprising a pile gripping device, such as a motion-compensating pile gripper, which is operated to hold the pile upright during driving, the vessel being, for example, a floating vessel.

15. A pile driving system for vertically driving a hollow, open-ended, large diameter steel pile into soil, the pile having a cylindrical top portion with a top portion wall thickness between an inner diameter and an outer diameter, wherein the outer diameter is at least 5 meters, the pile being, for example, a monolithic pile of an offshore wind turbine, the soil being, for example, the seabed. in, The system includes a pile driving device configured to be arranged on a top end of a pile, the pile driving device comprising: a driving head assembly having an annular contact surface configured to rest on a top end of the pile and an annular anvil surface above the annular contact surface, a steel impact weight having a mass of at least 100 tons, for example greater than 200 tons, said impact weight being vertically movable above the annular anvil surface of the driving head assembly, - a vertical guide structure configured to guide the impact weight vertically, wherein the driving head assembly is configured for energy transfer between the anvil surface and the contact surface for transferring energy from the falling impact weight to the contact surface and thereby to the pile top, - a lifting system configured to bring the impact weight into an initial height position relative to the anvil surface of the driving head assembly, - a quick release system adapted to achieve a quick release of the lifting system so that the impact weight falls from said initial height position onto the anvil surface of the driving assembly, The pile driving device is capable of repeated cyclic operation, wherein: -The impact counterweight is lifted to the initial height position through the lifting system, - operating the quick release mechanism to achieve a quick release of the lifting system, causing the impact weight to fall from the initial height position onto the anvil surface of the driving head assembly, wherein energy from the falling impact weight is transferred to the contact surface of the driving head assembly and thereby to the top end of the pile, causing the pile to be driven deeper into the soil, The impact weight comprises, preferably, a tubular impact weight made of steel, for example with a wall thickness between 10 cm and 20 cm.

16. The pile driving system according to claim 15, wherein: The impact weight is embodied as a tubular impact weight made of steel, for example with a wall thickness between 10 cm and 20 cm, wherein the tubular impact weight has a height between 4 m and 12 m, for example between 6 m and 10 m.

17. The pile driving system according to claim 15 or 16, wherein: A plurality of accelerator devices are provided in the pile driving device. The plurality of accelerator devices are arranged in a circular array and engaged with the tubular impact weight at distributed positions.

18. The pile driving system according to claim 15 or 16, wherein: The pile driving device is configured such that the tubular impact weight falls only under the force of gravity (1G), for example, the pile driving device does not have one or more accelerator devices for the impact weight.

19. A pile driving system according to one or more of claims 15 to 18, wherein: The tubular impact weight has a diameter such that in vertical projection the tubular impact weight overlaps the wall thickness of the top portion of the pile.

20. A pile driving system according to claims 15 to 19, wherein: The tubular impact weight has a central passage with a diameter of at least 2 meters, for example corresponding to at least 50% or 75% of the inner diameter of the top portion of the pile.

21. A pile driving system according to one or more of claims 15 to 20, wherein: The pile driving device comprises a housing extending coaxially around a tubular impact weight, the housing having an open lower end resting on a driving head assembly, and wherein the housing is preferably peripherally closed, and wherein, preferably, the housing has an open top end and has a central passage having a diameter corresponding to at least 50%, more preferably at least 75%, of the inner diameter of the top portion of the pile.

22. A pile driving system according to one or more of claims 15 to 21, wherein: The lifting mechanism comprises a plurality of hydraulic lifting cylinders, and wherein, preferably, the quick release system comprises one or more quick release valves that open to allow rapid discharge of hydraulic fluid from the lifting cylinders.

23. A pile driving system according to one or more of claims 15 to 22, wherein: The vertical guide structure includes roller assemblies, each roller assembly including one or more horizontal-axis rollers engaging a tubular impact weight, and wherein the roller assembly is configured to press the one or more rollers against the tubular impact weight with a preload.

24. A pile driving system according to one or more of claims 15 to 23, wherein: The energy transfer assembly of the driving head assembly includes one or more spring devices and / or one or more damper devices acting between the anvil surface and the contact surface.

25. A pile driving system according to one or more of claims 15 to 24, wherein The driving head assembly comprises a plurality of spring devices and / or a plurality of damper devices arranged in an annular array in the driving head assembly, for example, implemented as an integrated spring device and damper device.

26. A pile driving system according to one or more of claims 15 to 25, wherein The driving head assembly includes a plurality of cylinder devices arranged in an annular array in the driving head assembly, each cylinder device having a cylinder body, a piston and a chamber defined by the piston, wherein the chamber is filled with liquid, such as oil.

27. A pile driving system according to one or more of claims 15 to 26, wherein: The pile driving device includes a sleeve extending downwardly from the head end assembly along a top section of the pile.

28. A pile driving system according to one or more of claims 15 to 27, wherein The system further includes a vibration device.

29. The pile driving system according to claim 28, wherein: The vibration device is configured to generate an alternating force about a vertical axis of the pile at a vibration frequency to vibrate the pile about the axis and reduce friction between the pile and soil, such as the seabed.

Images