NL2022909B1 - A foundation pile - Google Patents

Abstract

The invention is directed to a foundation pile (1) comprising a tubular housing (2) having an upper end (3) and an open lower end (4) and wherein at or near the open lower end (4) the following means are present (i) vibration means (5), (ii) means (6) 5 to discharge a fluid into the interior space (20) of the tubular housing and (iii) means (7) to discharge a fluid from the lower end (4) of the tubular housing(2) in a direction which has a downward directional component. {Figure 2} 2022909

Description

A FOUNDATION PILE The invention is directed to a foundation pile comprising a tubular housing having an upper end and an open lower end and wherein at or near the open lower end means are present to discharge a fluid.

WO03/100178 describes a method to install a wind turbine at sea by vibrating a tubular foundation pile of a so-called monopile into the earth using a vibration arrangement clamped to the upper end of the foundation pile. The vibration arrangement may weigh 40-50 tonnes and may be one as described in US5653556. Once the tubular foundation pile is installed an intermediate part and a wind turbine tower is fixed to the tubular foundation. Next a nacelle and hub and blades are mounted.

WO15190919 described a method to upend, bring into a vertical position, of a combined foundation pile and a vibrating arrangement similar to the one disclosed in WO03/100178.

WO02/18711 describes a hammer fixed to the upper end of a foundation pile.

The hammer is provided with eccentric rotatable weights which may be electrically or hydraulically powered. The pile can be installed in the soil of a sea bed.

A disadvantage of the method of WO03/100178 is that the use of the vibration arrangement causes underwater noise and that the method is energy intensive. This is not desired from an ecological point of view. For this reason new foundation piles are developed which when installed result in significantly less noise and require less energy. One such a foundation pile is described in WO2017/203023. This publication describes a tubular foundation pile having an open lower end. The lower end of the tube is provided with an array of moving tips which movement is caused by rotating eccentric masses powered by a hydraulic motor. Further the tips are provided with outlet openings for water to achieve an upwardly moving flow of water along the outer and inner wall of the tube. When installing a foundation pile of this design significantly lower noise levels would result because it would avoid the use of a 40- 50 tonnes weight vibration device.

Although the design of WO2017/203023 is beneficial in many ways there is stil! room for improvement. For example, it appears that when the foundation pile of WO2017/203023 is used in harder soil it becomes difficult to penetrate this soil to a sufficient depth for the pile to serve as a foundation for, for example, a wind turbine.

The object of the present invention is therefore to provide a foundation pile which avoids the use of a noise generating vibration device described WO03/100178 and which has an improved soil penetration as compared to the foundation pile as described in WO2017/203023.

This is achieved by the following foundation pile. A foundation pile comprising a tubular housing having an upper end and an open lower end and wherein at or near the open lower end the following means are present (i) vibration means, (ii) means to discharge a fluid into the interior space of the tubular housing and (iii) means to discharge a fluid from the lower end of the tubular housing in a direction which has a downward directional component.

Applicant found that the combination of measures (i)-(iii) results in that the foundation pile can penetrate a soil deeper than the prior art foundation pile described in WO2017/203023. Applicants found that the soil resistance can be effectively reduced by having a vibration means located at the lower end of the tubular housing. The energy level of the source of vibration and thus also the noise level may be significantly lower as compared to when a vibration means are located at the upper end of the foundation pile as shown in WO03/100178. Furthermore the noise caused by the vibrating means will be effectively damped by the surrounding soil and by the length of the foundation pile which is already surrounded by soil when penetrating the soil. Thus vibration in combination with a clever way of reducing the soil resistance by adding water to said soil at the lower end of the foundation pile makes a better penetration at a lower noise level possible. The invention is therefore also directed to the following process.

Process to install a foundation pile comprising a tubular housing having an upper end and an open lower end into a mass of soil by making use of the gravitational forces resulting from the mass of the foundation pile and any optionally connected part to said foundation pile in the downward axial direction and wherein the soil resistance, which prevents the foundation pile from penetrating the soil, is reduced by (a) vibrating the tubular housing using a vibration means located at or near the open lower end of the tubular housing, (b) fluidising the soil as present in the interior of the tubular housing using water as a fluidising medium and (c) discharging downward projected jets of water from the lower end of the tubular housing.

In the description of the invention terms like upper, lower, upwardly downwardly, upward, downward, above, below are used to describe the invention in its most typical configuration when used as a foundation pile. This language does not in any manner limit the invention to such configuration. Thus foundation piles having another position, for example lying horizontally in storage, may still be according to the present invention. The lower end of the foundation pile according to the invention may be provided with an array of moveable tips as described in WO2017/203023 in addition to the means (i)-(iii). Preferably the lower end of the foundation pile is a fixed or non- moving arrangement, preferably this lower end is a downward directed non-moving pointed end. The vibration means may be positioned at the outer wall of the tubular housing near the lower end of the tubular housing. Preferably the vibration means are a series of individual vibration devices positioned at the interior wall of the tubular housing near the lower end of the tubular housing. By near is here preferably defined that the distance between the vibration device and the lower end of the foundation pile is less than internal radius of tubular housing. The vibration devices are preferably at the interior wall of the tubular housing because of the local fluidised bed causing a low sail friction.

The individual vibration device suitably comprises of a motor connected to a rotating eccentric mass which in use results in a vibration of the foundation pile. The motor may be an electric, pneumatic or hydraulic motor. Preferably the motor is a hydraulic motor. An advantage of a hydraulic motor is that water used to power the hydraulic motor may be discharged via the means (ii) to discharge a fluid into the interior space of the tubular housing. In this way less fluid is required to be directly fed to such means (ii). The hydraulic motor will be connected to a supply for water, preferably supplying water from a more elevated position.

Vibration means making use of an eccentric mass are known as for example described in the aforementioned WO0218711. The vibration means may be positioned to effect an axial vibration, a tangential or torsional vibration and/or a radial vibration. Preferably the individual vibration devices are positioned such that at least one of an axial vibration or a tangential (torsional) vibration results. Therefore the axis of rotation of the eccentric mass or masses of the individual vibration devices are preferably directed in a radial direction with respect to the tubular housing.

Suitably the individual vibration devices are positioned in a ring along the interior wall of the tubular housing. The rotating eccentric masses of the individual vibration device are suitably rotatably interconnected such to synchronise their motion. Applicants believe that such a ring of interconnected eccentric masses is new and inventive and therefore the invention is also directed to a vibration device comprising of multiple rotating eccentric masses which are rotatably interconnected such to synchronise their motion and are placed in a ring shaped housing. The rotating eccentric masses are suitably connected to one or more electric, pneumatic or hydraulic motors. The axis of rotation of the eccentric masses are suitably directed in a radial direction with respect to the ring shaped housing. The vibration device is 5 suitably used as a means to install a foundation pile into soil. Suitably the vibration device is suitably detachably connected to a lower end part of the foundation pile such that it can be removed once the pile is installed. Other preferred features of the vibration device may be those described in this description and figures of this application. For example the vibration device may be provided with fluid outlet openings as described for the foundation pile.

The means to discharge a fluid into the interior space of the tubular housing have the function to provide enough fluid to fluidise the soil present in this interior space when the foundation pile moves downwards into the soil. Suitably these means to discharge a fluid are an array of more than one outlet openings arranged in a ring along the interior wall of the tubular housing and wherein the direction of the fluid has an upward and an inward directional component. Suitably these means to discharge a fluid are fluidly connected to fluid supply conduits which supply a fluid from the upper end of the foundation pile. The means to discharge a fluid may also be fluidly connected to a fluid outlet of a hydraulic motor of the vibration means. The supply of fluid may be separate such that one group of outlet openings are fluidly connected to a fluid outlet of a hydraulic motor of the vibration means and another set of outlet openings are fluidly connected to the fluid supply conduits.

Suitably the means to discharge a fluid into the interior space of the tubular housing further comprise more than one outlet openings to discharge a fluid along the interior wall of the tubular housing. The outlet openings will be arranged in a ring and the direction of the fluid has an upward direction along the inner wall of the tubular housing.

Preferably the lower end of the tubular housing is a ring shaped element having a downwardly pointed end.

The ring shaped element is preferably provided with an array of fluid outlet openings suited to discharge a fluid from the lower end of the tubular housing in a direction which has a downward directional component.

The ring shaped element may have an angled, also referred to as pointed, outer surface and/or an (pointed) angled inner surface.

With angled or pointed surface is meant any surface which does not run parallel to the outer or inner wall of the tubular housing.

For example the outer surface may be angled and the inner surface may be parallel.

In such a configuration the outer surface may be provided with outlet openings to discharge a fluid downwardly and radially outwardly.

At the lower pointed end of such a ring shaped element outlet openings may be present which direct the fluid in a downward direction . Preferably the ring shaped element has a pointed inner surface and wherein the pointed inner surface is provided with outlet openings to discharge a fluid from the lower end of the tubular housing in a direction which has a downward directional component and a component in the direction of the axis of the tubular housing.

More preferably at the lower pointed end of the ring shaped element outlet openings are present which direct the fluid in a downward direction.

Such a ring shaped element is further provided with outlet openings at the outer surface to discharge a fluid from the lower end of the tubular housing in a direction which has a radial outward directional component.

The ring shaped element may comprise of a ring of the afore mentioned vibration means positioned above the means to discharge a fluid from the lower end of the tubular housing.

The ring shaped element may further comprises a ring of the afore mentioned outlet openings to discharge a fluid into the interior of the tubular housing positioned above the ring of vibration means.

The ring shaped element having such combined functionalities may be fixed to the inner wall of the tubular housing in a permanent manner, such as for example by means of welding or bolted.

The ring shaped element may also be detachably connected to the interior wall of the tubular housing.

For example by means of hydraulic operated cross bars which press the ring shaped element onto the inner wall. Such cross-bars may also be provided with outlet openings for a fluid. A detachable ring shaped element is advantageous because it enables one to reuse the relatively complex element in another foundation pile according to the invention.

The tubular housing of the foundation pile may be made of every material. Because the vibration means are located at the lower end of the foundation pile materials may be used which would not have survived a vibration or hammering means fixed to its upper end. Tubular housings made of composites such as being developed by Jules Dock, Rotterdam, The Netherlands for wind turbines may be used. The tubular housing is suitably made of steel because steel is currently the material of choice in this industry. The foundation pile may have any dimension. Preferably the internal diameter of the tubular housing is at least 1 meter such to accommodate the means (i)-(iii). There is not real maximum internal diameter. Tubular housings having internal diameters of up to 50 meter may be used. The foundation pile may be any foundation pile which needs to be fixed in soil. The foundation pile according to the invention is advantageously used in a soil covered by a body of water, like in a lake or sea. In this way the fluidisation of the soil within the tubular housing will be most effective in reducing the soil resistance. The foundation pile may be an anchor onto which a larger structure may be placed. For example a number of installed foundation piles according to the invention and positioned in a fixed pattern may be used to fix a foundation of a wind turbine having inserts according to the same pattern. The foundation may then be a framework or the like. The foundation pile may suitably be part of a monopile of a wind turbine. Preferably the tubular housing is a metal tubular housing having a diameter of at feast 1 meter and wherein the upper end of the tubular housing is connected to a monopile transition piece of a wind turbine. Even more preferably the tubular housing is a metal tubular housing having a diameter of at least 1 meter and wherein the upper end of the tubular housing is connected to a monopile comprising a wind turbine. Installing the foundation pile making use of means (i)-(iii) while a complete wind turbine is connected to the foundation pile is advantageous because the mass of the wind turbine will assist in the installation of the foundation pile. Lifting devices as disclosed in WO2018/151594 or NL2021129 can be used to position such a complete wind turbine in a vertical position on the sea bed after which the foundation pile according to this invention can install itself making use of means (i)-(iii). Alternatively the process according to this invention may be used to install such a foundation pile with monopile transition piece or the entire monopile wind turbine.

In the process according to this invention the foundation pile comprising a tubular housing having an upper end and an open lower end is installed into a mass of soil by making use of the gravitational forces resulting from the mass of the foundation pile and any optionally connected part to said foundation pile in the downward axial direction. The soil resistance, which prevents the foundation pile from penetrating the soil, is reduced by (a) vibrating the tubular housing using a vibration means located at or near the open lower end of the tubular housing, (b) fluidising the soil as present in the interior of the tubular housing using water as a fluidising medium and (c) discharging downward projected jets of water from the lower end of the tubular housing.

The frequency of the vibration means is suitably between 10 and 200 Hz. The direction of the vibrating tubular housing may be axial, torsional and/or radial and more preferably at least axial and/or torsional. The fluid may be fresh water or sea water. The process is advantageously applied in a soil covered by a body of water, like in a lake or sea. The fluid used in the process is preferably the same as the type of water of the body of water. Thus for example salt water when the body of water is a sea. The amount of fluid supplied to the interior of the tubular housing is such that the soil as present in this space is fluidised. The amount of fluid, like for example the amount to achieve the minimum fluidization velocity, will mainly depend on the type of soil and can be determined by one skilled in the art using ordinary fluidized bed reactor engineering guidelines. The minimum fluidization velocity is mostly dependent on the particle size and particle density of the soil and fluid viscosity and fluid flow velocity.

In the process the vibration is achieved by using a number of individual vibration devices comprising of a hydraulic motor connected to a rotating eccentric mass as positioned in a ring along the interior wall of the tubular housing which in use results in a vibration of the tubular housing and wherein the rotating eccentric masses of the individual vibration device are rotatably interconnected such to synchronise their motion. The hydraulic motor is powered by a flow of water and wherein preferably the used water is used for fluidising the soil as present in the interior of the tubular housing.

The process is preferably performed using a foundation pile according to the invention. When a detachable ring shaped element is used it is preferred that this element is pulled upwards within the tubular housing once the foundation pile reached its desired penetration depth.

The invention shall be described by the following non-limiting Figures 1-7.

Figure 1 shows a foundation pile (1) comprising a tubular housing (2) having an upper end (3) and an open lower end (4).

Figure 2 shows the open lower end (4) of the foundation pile of Figure 1 in more detail. At this lower end (4) vibration means (5), means (6) to discharge a fluid into the interior space (20) of the tubular housing and means (7) to discharge a fluid from the lower end (4) of the tubular housing (2) in a direction which has a downward directional component. The individual vibrating devices (8) forming the vibration means (5) are present in a ring (12). The means (6) to discharge a fluid into the interior space (20) of the tubular housing are present in a ring (13) of an array outlet openings (29). The means (7) to discharge a fluid from the lower end (4) of the tubular housing( 2) are outlet openings (16) as present in a ring shaped element (17). The outlet openings (16) are present in a pointed inner surface (22) which has the shape of a frusto conical shaped surface (27). Fluid discharged from openings (16) flow in a direction which has a downward directional component and a component in the direction of the axis (24) of the tubular housing (2).

In Figure 2 the ring (12) and ring (13) are part of the ring shaped element (17). Such a ring shaped element (17) may be detachably connected to the interior wall (9) of the tubular housing (2). Also shown are an array of outlet openings (23) focated at the exterior of the ring shaped element. Further several conduits (28) are present running along the interior wall (9) to separately supply water to the vibration means (5), means (6) and means (7). In this way the different means can be supplied with water having a capacity and pressure optimised for the different means.

Figure 3 shows the ring shaped element (17) of Figure 2 as a separate element. An array of outlet openings(29) are shown which are arranged in a ring (13) as the means (6) to discharge a fluid into the interior space (20) of the tubular housing (2). The outlet openings (29) are positioned in a frusto-conical shaped surface (25) such that any fluid being discharged from said openings have an upward and an inward directional component. Further an array of outlet openings (14) are shown at the upper end of the frusto-conical shaped surface (25) such that any fluid being discharged from said openings has an upward direction along the interior wall (9) of the tubular housing (2). Figure 3 also shows an array of outlet openings (23) located at the exterior of the ring shaped element. Via these openings (23) a jet of fluid can be discharged sideways thereby further lowering the soil resistance. When the ring shaped element (17) has such external openings (23) it is preferred that the ring shaped element extends somewhat below the lower end of the tubular housing (2) such that these openings have a clear outflow space as shown in Figure 2. Figure 4 shows a cross-section of the ring shaped element (17) of Figure 3.

The gear wheel of eccentric mass (10a) of one device (8) is connected the gear wheel of eccentric mass (10b) of its neighbouring device (8). In this way the multiple rotating eccentric masses as present in the ring shaped element (17) are rotatably interconnected such to synchronise their motion.

Figure 5 shows the interior of a vibrating device (8). A bucket wheel (19) as the hydraulic motor (18) is seen. A flow of water will impact a wheel (19) of the hydraulic motor (18) tangentially resulting in a rotation. This rotation is transferred by means of a gearing wheel to a rotating eccentric mass (10a) which in tum transfers its rotation by means of a gearing wheel to a second eccentric mass (10b). use results in a vibration of the tubular housing (2). The eccentric masses (10a, 10b) rotate around their respective axis of rotation (11a,11b). Because the vibration device is fixed to the tubular wall (2) of the foundation pile (1) a vibration of the foundation pile and especially the lower part and end of the foundation pile will result.

The configuration as shown in Figure 5 is placed in a housing (26) as shown in Figure 6. This housing will also comprise the outflow openings (14) and (29) of the means (6) to discharge a fluid into the interior space (20) of the tubular housing (2) at an upper frusto conical surface (25) and openings (16) (not visible) of the means (7) to discharge a fluid from the lower end (4) of the tubular housing( 2) at a lower frusto conical surface (27). When such a device (8) is placed in a ring the axis of rotation (11a,11b) of the eccentric masses (10a, 10b) are directed in a radial direction with respect to the ring shaped element (17).

Figure 7 shows how ring shaped element (17) is connected to the lower end (4)

of the tubular housing (2). Ring shaped element (17) extend somewhat below the lower end (4) to enable a jet of fluid (arrow indicating flow direction) to be discharged via outlet openings (23) sideways, i.e. in a radially outward direction.

At the downwardly lower pointed end (21) of the ring shaped element (17) outlet openings (30) are present which direct the fluid in a downward direction as indicated by an arrow.

In this Figure also the positions and flow directions of all the other openings (16,29,14) are shown and indicated by arrows.

Also pointed end (21) is shown as a non-moving pointed end or arrangement.

The only moving parts are the wheels (19)

and eccentric masses (10a,10b) of the individual vibrating devices (8).

Claims (28)

CONCLUSIONS l. Foundation pile (1), comprising a tubular housing (2) comprising an upper end (3) and an open lower end (4), and in which the following means are provided at or near the open lower end (4) are (i) vibration means (5), (in) means (6) for delivering a fluid into the interior space (20) of the tubular housing, and (iii) means (7) for delivering a fluid from the lower end ( 4) from the tubular housing (2) in a direction that includes a downwardly directed component. Foundation pile according to claim 1, wherein the vibration means (5) is a series of individual vibration devices (8) positioned at the level of the inner wall (9) of the tubular housing (2), in the vicinity of the lower end (4) of the tubular housing (2). Foundation pile according to claim 2, wherein the individual vibration devices (8) consist of a motor 18) connected to a rotating eccentric mass (10a, 10b) which, during use, gives rise to a vibration of the foundation pile (1) . The foundation pile of claim 3, wherein the motor is a hydraulic motor (18). A foundation pile according to any one of claims 3 to 4, wherein the axis of rotation (11a, 11b) of the eccentric mass (10a, 10b) of the individual vibrators (8) is aligned in a radial direction with respect to the tubular housing ( 2). A foundation pile according to any one of claims 3 to 5, wherein the individual vibration devices (8) are positioned in a ring (12) along the inner wall (9) of the tubular housing (2), and wherein the rotating eccentric masses (10a) , 10b) of the individual vibration devices (8) are rotatably interconnected, in such a way that their movement is synchronized. A foundation pile according to any one of claims 1 to 6, wherein the means for delivering a fluid into the interior space (20) of the tubular housing (2) are more than one delivery openings (29) for delivering a fluid. positioned in a ring (13) along the inner wall (9) of the tubular housing (2), and in which the direction of the fluid comprises an upward and an inward directed component. $. Foundation pile according to claim 7, wherein the means (6) for delivering a fluidizing fluid into the interior space (20) of the tubular housing (2) is additionally positioned with more than one discharge openings (14) for delivering a fluidizing fluid. in a ring (15) along the inner wall (9) of the tubular housing (2), and in which the direction of the fluid comprises a component directed upwards along the inner wall (9) of the tubular housing (2). A foundation pile according to any one of claims 1 to 8, wherein the means (7) for delivering a fluid from the lower end (4) of the tubular housing (2) in a direction comprising a downwardly directed component, more then there are one discharge openings (16) which are in the form of an annular element (17) having a downwardly directed end (21). A foundation pile according to claim 9, wherein the annular element (17) has a pointed inner surface (22), and wherein the pointed inner surface (22) is provided with discharge openings (16) for discharging a fluid from the lower end (4) of the tubular housing (2), in a direction that includes a downward-facing component, as well as a component in the direction of the axis (24) of the tubular housing (2). Foundation pile according to claim 10, wherein, at the level of the downwardly directed end (21) of the annular element (17), discharge openings (30) are present which discharge the fluid in a downward direction. Foundation pile according to any one of claims 10 to 11, wherein the annular element is provided with discharge openings (23) at the level of an outer surface of the annular element (17) in order to discharge a fluid from the lower end (4) of the tubular housing (2), in a direction that includes an outwardly directed radial component. Foundation pile according to any one of claims 9 to 12, wherein the annular element (17) further comprises a ring (12) with vibration means (5), positioned above the means for delivering a fluid from the lower end of the tubular housing, as well as a ring (15) with discharge openings to deliver a fluidizing fluid into the interior (11) of the tubular housing (2), positioned above the ring (12) with vibration means (5), and provided in an upwardly directed end portion comprising an upwardly facing interior. Ring game according to claim 13, wherein the ring-shaped element (17) is releasably connected to the inner wall (9) of the tubular housing (2). Foundation pile according to any one of the claims through 14, wherein the tubular housing is a metal tubular housing having a diameter of at least 1 meter, and wherein the top end of the tubular housing is connected to a monopile junction of a wind turbine. A foundation pile according to any one of claims 1 to 14, wherein the tubular housing is a metal tubular housing having a diameter of at least 1 meter, and wherein the top end of the tubular housing is connected to a monopile which includes a wind turbine. 17. A method of installing a foundation pile comprising a tubular housing having an upper end and an open lower end, in a ground mass, using the force of gravity acting on the mass of the foundation pile and optionally including the foundation pile connected parts, in the downward axial direction, and in which the ground resistance that prevents the foundation pile from penetrating into the ground is reduced by (a) subjecting the tubular housing to a vibration by using vibration means that are located at or near the open lower end of the tubular housing, (b) fluidizing the soil as contained within the tubular housing interior, using water as the fluidizing medium, and (c) ) delivering downwardly directed water jets from the lower end of the tubular housing. 18. Method as claimed in claim 17, wherein the frequency of the vibration means is between 10 Hz and 200 Hz. A method according to any one of claims 17 to 18, wherein the direction of the vibrating tubular housing is axial and / or twisted. A method according to any one of claims 17 to 19, wherein the vibration is realized by using a plurality of individual vibration devices consisting of a hydraulic motor connected to a rotating eccentric mass positioned in a ring along the inner wall of the the tubular housing, thereby causing vibration of the tubular housing during use, and wherein the rotating eccentric masses of the individual vibration devices are rotatably interconnected in such a way that their movement is synchronized. The method of claim 20, wherein the hydraulic motor is driven by a water flow, and wherein the used water is used to fluidize the soil contained within the tubular housing. A method according to any one of claims 17 to 21, carried out by using a foundation pile according to any one of claims 1 to 16. A method according to any one of claims 17 to 21, performed using a foundation pile according to claim 14, and wherein, once the foundation pile has reached the desired depth of penetration, the annular element is pulled up in the tubular housing. 24. Vibration device, consisting of a plurality of rotating eccentric masses rotatably interconnected in such a way that their movement is synchronized, and placed in an annular housing. 25. Vibration device as claimed in claim 24, wherein the rotating eccentric masses are connected to one or more hydraulic motors. A vibration device according to any one of claims 24 to 25, wherein the rotational axes of the eccentric masses are aligned in a radial direction with respect to the annular housing. A vibration device according to any one of claims 24 to 26, wherein the eccentric masses are positioned in an annular housing having a frustoconical surface at its upper end, and a frustoconical surface at its lower end, and in which discharge openings for a fluid, are present in the upper and lower frusto-conical surfaces, with at least one radially inwardly directed fluid flow component, Use of a vibration device according to any one of claims 24 to 27, in a method of installing a foundation pile.