Patent Description:
It is known that pile driving is done by a hammer with a sleeve, wherein the sleeve is stabbed over the pile. The hammer delivers one or more blows to the pile, thereby driving the pile into the ground formation.

For the sake of completeness, attention is drawn to the following prior art. <CIT> relates to a system and a method for installing tubular foundation elements in an underwater ground formation, the system comprising a hydraulic driver, an anvil and an adaptor for transmitting energy from the anvil to the toe of the foundation element, which adaptor fits inside the tubular foundation element. The inner wall of the foundation element is provided with a support for the adaptor at or near its toe.

<CIT> discloses an offshore foundation for mounting thereon a wind turbine. The monopile of the foundation is provided with an internal flange portion for support of an anvil.

<CIT> relates to a pile-driving machine, comprising a ram, a pile, an inner sleeve and a hoisting device. The inner sleeve is located in a lower part of the outer sleeve. The ram can move upwards and downwards within the outer sleeve, thereby directly hitting the inner sleeve. Lugs are projecting from the ram, which lugs strike the top of the outer sleeve to move the outer sleeve downwards.

<CIT> relates to driving long piles into submerged lands with a liquid ram or spear generated in an evacuated tube. In one embodiment, the pile itself is used as at least a portion of the working chamber for generating a water hammer.

<CIT>relates to a driving assembly for installing piles in a ground formation.

It is an object of the present invention to provide an assembly comprising a tubular foundation element which does not require or requires less removal of soil material.

To this end, the presently provided assembly is according to claim <NUM>.

During installation of the tubular foundation element, a driver is placed on the support provided at the inside of the tubular foundation element and the tubular foundation element penetrates the soil material of the ground formation, in particular an underwater ground formation, and the soil material enters the tubular foundation element. At a predetermined point during driving of the tubular foundation element, the anvil and the support hit the soil material, thereby forcing the soil material to move downwards. As a result, the part of the tubular foundation element above the support contains no or little soil material.

Moreover, the soil material within the tubular foundation element is compressed during installation of the tubular foundation element and, therefore, becomes more dense. If a further element is inserted into the tubular foundation element, for instance a jacket leg of a jacket, grout may be provided around the further element and within the tubular foundation element to provide a fixation of the further element relative to the tubular foundation element. Due to the more dense soil material, mixing of the grout with the soil material may be prevented or reduced and grouting is improved.

It is noted that in the context of the present patent application, the term directly is referred to as without changing direction, and is also referred to as with nothing in between. Thus, the energy transmitted from the anvil to the tubular foundation element does not change direction during transmittal as such.

In a preferred embodiment, the support is provided in the upper half of the tubular foundation element, in particular in the upper quarter of the tubular foundation element. In this respect, 'upper' refers to a tubular foundation element which is vertically oriented. In a more specific embodiment, the tubular foundation element has a length in a range from <NUM> to <NUM>, preferably in a range from <NUM> to <NUM>, and the support is placed at a distance from the at least one open end, which distance is in a range from <NUM> to <NUM>, in particular in a range from <NUM> to <NUM>, and/or in a range from <NUM>% to <NUM>%, in particular in a range from <NUM>% to <NUM>% of the total length of the tubular foundation element. In this embodiment, the upper part of the tubular foundation element, i.e. the part above the support, stays clean during installation of the tubular foundation element. In the upper part, a jacket leg may be inserted and fixed with respect to the tubular foundation element by means of grout. Due to the clean upper part of the tubular foundation element, no removal of soil material is required before grouting.

The support may comprise a flange secured to an inner surface of the tubular foundation element. The flange may be secured, e.g. welded or bolted, to the inner surface, in particular an inner wall of the tubular foundation element.

The support may be substantially tapered towards the toe of the tubular foundation element in the longitudinal direction thereof. In this respect, 'toe' refers to the lowermost end of the tubular foundation element. Due to the tapered shape of the support towards the toe of the tubular foundation element, the energy delivered via the anvil to the support is transmitted efficiently to the wall of the tubular foundation element.

The invention further relates to a method of installing a tubular foundation element in a ground formation, by means of a pile driver according to claim <NUM>.

The support may be provided in the upper half of the tubular foundation element, in particular in the upper quarter of the tubular foundation element. In this respect, 'upper' refers to a tubular foundation element which is vertically oriented.

In an embodiment the driver and/or anvil are held by the tubular foundation element during driving thereof.

In a preferred embodiment, the tubular foundation element is placed directly on the ground formation and driven into the ground formation. The anvil compresses soil material of the ground formation within the tubular foundation element during at least a part of a installing process of the tubular foundation element. Usually, the upper layer of the ground formation, in particular underwater ground formation, has to be excavated before the tubular foundation element may be installed in the ground formation.

Thus, as explained above, the upper part of the tubular foundation element, i.e. the part above the support, contains no or little soil material after installation of the tubular foundation element. Therefore, the upper part of the tubular foundation element does not require to be emptied after installation. Further, the soil material within the tubular foundation elements is compressed during installation of the tubular foundation element. Due to the compression of the soil material of the ground formation, the soil material of the ground formation, in particular the upper layer, is more dense after installation.

Due to compression of the soil material during installation, the tubular foundation element may be placed onto the ground formation, in particular a ground formation with a soft upper layer, without excavating the upper layer of the ground formation.

The method may further comprise a step of placing a template having at least two guides for guiding a tubular foundation element on the ground formation, in particular before the tubular foundation element is placed on the ground formation.

In an embodiment, when the tubular foundation element is installed in an underwater ground formation, water may be relieved from the tubular foundation element, in particular at least from the part between the underwater ground formation and the support, during installation of the tubular foundation element in the underwater ground formation.

It is preferred that the pile driver comprises a hydraulic pile driver.

The assembly may comprise a template having at least two guides for guiding a tubular foundation element, which template is to be placed on the underwater ground formation, at least during installing the tubular foundation element.

Aspects of the invention will be explained in greater detail by reference to exemplary embodiments of the invention shown in the drawings, in which:.

In practice, installation of a jacket, e.g. for a wind turbine, starts with installing a number a jacket piles in a ground formation, e.g. an underwater ground formation. After installing the jacket piles, jacket legs of the jacket are placed within the jacket piles. A jacket leg extends in the upper part of a jacket pile. Grout may be added to the jacket pile, in particular the upper part of the jacket pile, in order to fixate the jacket leg with respect to the jacket pile.

To this end, <FIG> shows an embodiment of a tubular foundation element <NUM>, in this embodiment a jacket pile <NUM> which might be installed in an underwater ground formation <NUM>. The tubular foundation element <NUM> is placed on the surface of the underwater ground formation <NUM> and is held by a guide <NUM> of a template <NUM>. In this example, the jacket pile <NUM> has a circular cross-section and a diameter in the range from <NUM> to <NUM>.

The jacket pile <NUM> is provided with a support, in this embodiment a flange <NUM> provided at an inner wall of the jacket pile <NUM>. The flange <NUM> is attached to the inner wall of the jacket pile <NUM> by, e.g. welding, bolting, or any suitable manner to attach the flange <NUM> to the inner wall of the jacket pile <NUM>.

In an embodiment, the flange <NUM> may be provided with openings (not shown) in order to let water out from the lower part of the jacket pile <NUM> below the flange <NUM>. It is therewith prevented that the water pressure within the lower part of the jacket pile <NUM> exceeds a predetermined value as a result of driving the jacket pile <NUM> by means of the driver <NUM>, in particular a hydraulic driver, which driver delivers blows to the flange <NUM>. In this embodiment the blows are delivered directly to an upper side, i.e. top surface of the flange <NUM>.

In other embodiments, openings (not shown) might be provided in the tubular foundation element <NUM> and/or in an anvil <NUM> to let water out from the lower part of the tubular foundation element <NUM> below the support <NUM>.

As can be seen in <FIG>, when the jacket pile <NUM> is installed in the underwater ground formation <NUM>, the flange <NUM> is below the surface of the underwater ground formation <NUM>.

As can be seen in <FIG>, a driver <NUM> with an anvil <NUM> is placed on top of the support <NUM>, such that energy is transmitted from the anvil <NUM> directly to the tubular foundation element <NUM>, during installation of the tubular foundation element <NUM>. The driver <NUM> and the anvil <NUM> deliver blows to the flange <NUM> and therewith to the tubular foundation element <NUM> to install the tubular foundation element <NUM> in the underwater ground formation <NUM>. At a predetermined point during installing of the tubular foundation element <NUM>, the flange <NUM> and the anvil <NUM> reach the surface of the underwater ground formation <NUM>.

Installing of the tubular foundation element <NUM> continues and the flange and in particular the anvil <NUM> delivering blows to the flange <NUM> of the tubular foundation element <NUM> deliver blows to the soil material within the tubular foundation element. As a result, the soil material <NUM> within the tubular foundation element <NUM> is compressed and becomes more dense, at least the soil material directly below the anvil <NUM> and the flange <NUM>.

It is noted that the driver <NUM> with the anvil <NUM> can be hoisted by a hoisting device such as a crane (not shown), which crane is for example placed on a surface vessel, such as a jack-up barge (not shown). The driver may be a hydraulic driver, e.g. one out of the IHC Hydrohammer S-series connected to a power pack on board of a surface vessel (not shown).

In practice the length B of the legs of the jacket in <FIG> may be <NUM>. In the installed state, the tubular foundation element <NUM> may extend a distance D above the surface of the underwater ground formation <NUM>, which distance D in this example is <NUM>. The length C is in this example in a range from <NUM> to <NUM>, in particular in a range from <NUM> to <NUM>, and/or in a range from <NUM>% to <NUM>%, in particular in a range from <NUM>% to <NUM>% of the total length of the tubular foundation element <NUM>.

Due to the anvil <NUM> with the driver <NUM> forcing the soil material to move downwards during driving of the tubular foundation element <NUM>, it is not required to empty the part of the tubular foundation element <NUM> above the flange <NUM> after installation. As a result of compressing the soil material within the tubular foundation element <NUM>, the soil material is more dense and is a good match for the grout used to fixate the jacket leg <NUM> relative to the jacket pile <NUM>, i.e. grouting is improved.

In this embodiment, the jacket leg <NUM> comprises welding beads <NUM>, which may contribute to the fixation of the jacket leg <NUM> to the tubular foundation element <NUM>. The jacket leg <NUM> is inserted partly into the tubular foundation element <NUM> as indicated with arrow A.

As a further result, the compressed soil material is more dense. Due to the more dense soil material, mixing of the grout and the soil material is prevented or reduced, which leads to a reliable fixation of the jacket leg to the tubular foundation element <NUM>.

Further advantages of the tubular foundation element as presently provided are as follows. The tubular foundation element <NUM> is installed in the ground formation by driving within the tubular foundation element <NUM>. As a result thereof, the tubular foundation element <NUM> acts as a noise reducing element. As a further result, the diameter of the tubular foundation element <NUM> is not enlarged during driving. Thus the tubular foundation element <NUM> may be installed without additional structural elements at the outside of the foundation element and/or without adjusting the guide <NUM> of the template <NUM>.

A further advantage is a low centre of gravity due to the pile driver <NUM> being inserted in the tubular foundation element <NUM> during driving thereof.

Moreover, since the anvil <NUM> is placed on the support <NUM> during driving of the tubular foundation element <NUM>, energy delivered to the support by, i. the anvil <NUM> is transmitted to the wall of the tubular foundation element. The transmitted energy is in particular transmitted downwards, i.e. via the wall of the tubular foundation element <NUM>, in particular from the support <NUM> towards the toe of the tubular foundation element. As a result, the part of the tubular foundation element <NUM> contributing to the generation of noise is reduced.

It is noted that the drawings are schematic, not necessarily to scale and that details that are not required for understanding the present invention may have been omitted. The terms "upward", "downward", "below", "above", and the like relate to the embodiments as oriented in the drawings, unless otherwise specified. Further, elements that are at least substantially identical or that perform an at least substantially identical function are denoted by the same numeral.

It is, for example possible that a noise mitigation system is used during installing of the tubular foundation element. The noise mitigation system comprises a tubular sleeve, which can be placed around the tubular foundation element during driving thereof. The tubular sleeve reduces the noise produced during driving of the tubular foundation element. The noise mitigation system may be used in combination with a template as described above.

Claim 1:
Assembly comprising
a tubular foundation element (<NUM>), in particular a pile e.g. a jacket pile, to be installed in a ground formation (<NUM>), a pile driver (<NUM>) and an anvil (<NUM>), the tubular foundation element (<NUM>) having at least one open end, allowing the pile driver (<NUM>) with the anvil (<NUM>) to be inserted into the tubular foundation element (<NUM>), wherein the tubular foundation element (<NUM>) has two open ends, wherein the tubular foundation element (<NUM>) comprises a support (<NUM>) at the inside thereof,
wherein
the support (<NUM>) is adapted to transmit energy from the anvil (<NUM>) directly to the tubular foundation element (<NUM>), during installation of the tubular foundation element (<NUM>), wherein the anvil (<NUM>) and the support (<NUM>) are configured such that during installation of the tubular foundation element (<NUM>) to a position in which the tubular foundation element (<NUM>) extends a distance above the surface of the ground formation the distance being for example <NUM>, soil material that enters the tubular foundation element (<NUM>) below the anvil (<NUM>) and the support (<NUM>) is directly compressed by both the anvil (<NUM>) and the support (<NUM>), wherein the anvil (<NUM>) and the support (<NUM>) are configured such that the part of the tubular foundation element above the support after such installation of the tubular foundation element contains no or little soil material.