Patent Description:
Further, the present invention relates to an arrangement comprising a marine foundation and an object.

Furthermore, the present invention relates to a use of a marine foundation.

Even further, the present invention relates to a method of installing a marine foundation.

Additionally, the present invention relates to a method of de-installing a marine foundation.

Different kinds of marine foundations are known, in which the marine foundation structure is made by pile-driving the framework structure submerged in water to the bottom. The use of one large pile anchored or submerged to the bottom is known as a different alternative. A third alternative is to transport to the installation site or to manufacture on site a massive foundation structure of steel and/or concrete, onto which a construction or object can be joined above the water surface.

The problem with the previously used solutions has been the heavy special equipment needed in the transport and installation of the foundation structures, which is available to a very limited extent. In addition, the use of special equipment is very expensive, especially when preparing the foundation structures in offshore circumstances, in which the weather windows suitable for working are short. The time needed for installation is long in relation to the weather window that can be predicted, even in ideal conditions. Fast and hard changes in weather may interrupt the foundation project, and may even force to demobilize and remobilize expensive equipment. If several foundation structures are to be installed in the same area, for example when building a wind park, it is extremely difficult to work out a fixed schedule, and advantages of serial production are lost.

<CIT>, for example, discloses a marine foundation structure comprising a shell structure which is thin in relation to the diameter of the structure. The shell structure is filled with soil.

Another type of marine foundation is disclosed in document <CIT>.

Document <CIT> further discloses a gravity based marine foundation.

Further, document <CIT> describes an offshore structure including a foundation to be located on a sea floor and a base column fixed to the foundation. The foundation comprises a hollow structure having an open bottom surface and an open top surface. The hollow structure will settle on the sea floor by its own structural mass.

Additionally, cited document <CIT> teaches a marine foundation that is partially built on land, is able to float, can be towed to an installation site and then be lowered to the seabed by filling a cavity with ballast.

In view of the foregoing, it would be beneficial to provide a marine foundation capable of being easily transported, installed and de-installed without use of special heavy equipment such as jack-up vessels and the like. The equipment required for transportation, installation and de-installation of the marine foundation should be moderately priced standard equipment. Certain embodiments of the marine foundation should be capable of being used in arctic weather conditions. The marine foundation should be further capable of being manufactured in industrial scale. Additionally, certain embodiments of the marine foundation should be capable of being used as a foundation for an offshore wind energy power plant.

According to a first aspect of the present invention, there is provided a marine foundation comprising a planar base, a perimeter wall and a cover forming a shell structure having a cavity, a hollow structure extending through an opening in the cover to the base, wherein within the cavity a plurality of compartments is formed, wherein the marine foundation is configured to change from a floating state to a semi-submerged state by pumping of material capable of being pumped into the cavity, wherein the marine foundation is configured to change from the semi-submerged state to the floating state by pumping of material capable of being pumped out of the cavity, and wherein in the floating state at least the cover and a part of the hollow structure are located above a water surface, and wherein in the semi-submerged state the base is positioned on a seabed, wherein the base is polygonal, the cover is polygonal and planar, the perimeter wall has a plurality of planar sides protruding from the polygonal base to the polygonal cover, wherein the plurality of compartments is formed by inner walls extending from at least two edges to the hollow structure, wherein each edge is formed between two adjacent planar sides of the perimeter wall, and wherein each planar side of the perimeter wall is inclined at an angle to the polygonal base in a range between <NUM>° and <NUM>°.

According to a second aspect of the present invention, there is provided an arrangement comprising a marine foundation according to any one of claims <NUM>-<NUM> and an object coupled to a coupling section of the hollow structure of the marine foundation. According to a certain embodiment of the present invention, the object comprises a wind energy power plant, a light house, a seamark, a part of a bridge, or a marine structure.

According to a third aspect of the present invention, there is provided a use of a marine foundation according to any one of claims <NUM>-<NUM>, wherein an object is coupled to a coupling section of the hollow structure of the marine foundation.

According to a fourth aspect of the present invention, there is provided a method of installing a marine foundation, the method comprising providing at an installation site a floating marine foundation comprising a polygonal and planar base, a perimeter wall having a plurality of planar sides protruding from the base to a polygonal and planar cover, thus forming a shell structure having a cavity, a hollow structure extending through an opening of the cover to the base, wherein within the cavity a plurality of compartments is formed by inner walls extending from at least two edges to the hollow structure, wherein each edge is formed between two adjacent sides of the perimeter wall, and wherein each planar side of the perimeter wall is inclined at an angle to the polygonal base in a range between <NUM>° and <NUM>°, and filling the cavity at least partially with ballast by pumping of material capable of being pumped in order to lower the base of the marine foundation to a seabed.

According to a fifth aspect of the present invention, there is provided a method of de-installing a marine foundation, the method comprising providing at a de-installation site a semi-submerged marine foundation comprising a polygonal and planar base, a perimeter wall having a plurality of planar sides protruding from the base to a polygonal and planar cover, thus forming a shell structure having a cavity, a hollow structure extending through an opening of the cover to the base, and wherein within the cavity a plurality of compartments is formed by inner walls extending from at least two edges to the hollow structure, wherein each edge is formed between two adjacent planar sides of the perimeter wall, and wherein each planar side of the perimeter wall is inclined at an angle to the polygonal base in a range between <NUM>° and <NUM>°, and removing ballast from the cavity by pumping material capable of being pumped in order to change the state of the marine foundation to a floating state.

Considerable advantages are obtained by means of certain embodiments of the present invention. A marine foundation and a method of installing a marine foundation are provided. The design of the marine foundation is such that land-based construction of the marine foundation can take place, for example at a harbour or shipyard, and then the floating marine foundation can be towed to a sea-based installation site prior to installing it at the installation site by ballasting the marine foundation. Thus, a jack-up vessel comprising a crane or similar other heavy equipment is not required at the installation site for installation of the marine foundation. The marine foundation is typically mainly built on land. The marine foundation may be finalized when being positioned at the bottom at a quay. In other words, the marine foundation is typically not built in a floating condition. The design of the marine foundation according to certain embodiments is further such that the marine foundation is able to float even in shallow waters prior to installation. This is of importance in case that the marine foundation has to be towed to the final installation site via shallow waters. Installation at the installation site by changing the state of the marine foundation from a floating state to a semi-submerged state can take place utilizing ballast water. In the semi-submerged state the cavity of the marine foundation may be completely filled with ballast water or with ballast water and pressurized air. In a similar way, de-installation of the marine foundation, for example <NUM> years after installation, is possible by removing ballast water or any other sort of ballast present in the shell structure. This may, for example, take place utilizing pressurized air and/or pumps. Also sand, gravel or material capable of being pumped may be present instead or in addition to water in the shell structure. Consequently, transportation, installation and de-installation of the marine foundation can take place quickly, safely, reliably, easily and cost-efficiently without that use of special heavy equipment is required. The equipment required for transportation, installation and de-installation of the marine foundation is moderately priced standard equipment such as tugs, pumps, means for providing pressurized air, etc. The structure of the marine foundation is further strong enough to allow towing.

According to certain embodiments of the present invention, only minor preparation of the seabed has to be carried out prior to installation of the marine foundation. For example, only a gravel layer has to be provided on the seabed prior to installation of the marine foundation. The design of the marine foundation is such that a low accuracy in gravel layer tolerances is sufficient for installation of the marine foundation. Consequently, pre-treatment of the seabed can be carried out quickly, cost-efficiently and with standard equipment such as a dredger or an excavator positioned on a lighter or barge. According to certain other embodiments, there is no preparation of the seabed required at all prior to installation of the marine foundation. For example, it may not be required to drive a pile or to pre-treat moraine by exploding when installing a seamark.

The marine foundation in accordance with the present invention is further easily scalable depending on its intended use. Certain embodiments of the present invention may be used in connection with installation of objects such as offshore wind energy power plants, lighthouses, seamarks, marine structures or as structures of a bridge.

According to certain embodiments of the present invention, a wind energy power plant can be coupled to the marine foundation e.g. in a harbour prior to towing the combined unit including the marine foundation and the wind energy power plant to the installation site. At the installation site, the state of the combined unit is then changed from a floating state to a semi-submerged state as described above. Thus, heavy installation equipment is not required at the sea-based installation site and the wind energy power plant can be installed quickly, safely, reliably, easily and cost-efficiently.

According to certain embodiments of the present invention, the marine foundation is capable of being used in arctic weather conditions due to arrangement of an ice protector or an ice shield.

According to the present invention, each side of the perimeter wall is inclined at an angle to a horizontal plane in a range between <NUM>° and <NUM>° and preferably in a range between <NUM>° and <NUM>°. As a result, the marine foundation is able to float even in very shallow waters when the cavity is filled with air or pressurized air.

For a more complete understanding of particular embodiments of the present invention and their advantages, reference is now made to the following descriptions, taken in conjunction with the accompanying drawings. In the drawings:.

In this document, the term "marine foundation" is used. The term "marine foundation" includes an offshore foundation, an inshore foundation to be installed near the coastline as well as a foundation structure to be installed in rivers and lakes.

In this document, the word "polygonal" is used. The word "polygonal" means a geometric form having a number of corners, for example a triangular form, a quadrangular form, a hexagonal form, or an octagonal form. The number of corners can be three or more. Preferably, the polygonal form is symmetrical.

In this document, the expression "material capable of being pumped" is used. Of course, said material includes water. However, said expression also includes other material that can be transported from one position to another position utilizing pumps. The expression further includes material that cannot be transported from one position to another position utilizing only pumps, but also material that can be transported from one position to another position utilizing pumps and an additive which creates the pumping capability of the material during the pumping process. Such an additive may be, for example, water.

In <FIG> a schematic perspective view of a part of a marine foundation <NUM> in accordance with at least some embodiments of the present invention is illustrated. The shown marine foundation <NUM> comprises a hexagonal base <NUM>, a perimeter wall <NUM> having six sides <NUM>, i.e. outer walls, protruding from the base <NUM> to a hexagonal cover (not shown), thus forming a shell structure. The hexagonal base <NUM> and the hexagonal cover are symmetrical to provide a shell structure that can be uniformly loaded with ballast. The sides <NUM> are typically, but not necessarily, planar. The base <NUM> and the cover <NUM> are typically planar. Between two adjacent sides <NUM> an edge <NUM> is formed. The shell structure is typically made of concrete. Within the shell structure formed by the base <NUM>, the perimeter wall <NUM> and the cover a cavity <NUM> is formed. Further, a hollow structure (not shown) extends through an opening (not shown) of the cover to the base <NUM>. Within the cavity <NUM> a plurality of compartments <NUM> is formed by inner walls <NUM> extending from each edge <NUM> formed between two adjacent sides <NUM> of the perimeter wall <NUM> to the hollow structure <NUM>. The inner walls <NUM> are typically also made of concrete. According to certain embodiments, the number of sides <NUM> is different than the number of inner walls <NUM>, i.e. the number of compartments <NUM> is not necessarily linked to the shape of the perimeter wall <NUM> or the base plate <NUM>. For example, the base <NUM> may be quadrangular, the cover <NUM> may be quadrangular and two compartments <NUM> are formed within the cavity <NUM> by two inner walls <NUM>.

Each side <NUM> of the perimeter wall <NUM> comprises a plurality of first profiles <NUM> arranged parallel or substantially parallel to each other. In other words, each side <NUM> of the perimeter wall <NUM> is reinforced by the first profiles <NUM>. The first profiles <NUM> are orientated in a direction perpendicular or substantially perpendicular to the Earth's normal, i.e. in a horizontal direction. The first profiles <NUM> are comprised by the sides <NUM> of the perimeter wall <NUM> or attached to each inner side <NUM> of the perimeter wall <NUM>. The sides <NUM> may comprise a plurality of connector plates (not shown) to which the first profiles <NUM> are welded, for instance. The first profiles <NUM> typically extend along the entire width of each side <NUM> of the perimeter wall <NUM>. The first profiles <NUM> may be T-shaped profiles, for instance. The first profiles <NUM> may be, for example, made of steel.

Further, each inner wall <NUM> comprises a plurality of second profiles <NUM> arranged parallel or substantially parallel to each other. In other words, each inner wall <NUM> of the perimeter wall <NUM> is reinforced by the second profiles <NUM>. The second profiles <NUM> are orientated in a direction perpendicular or substantially perpendicular to the Earth's normal, i.e. in a horizontal direction. In <FIG>, the second profiles <NUM> are comprised by or attached to only one side of each inner wall <NUM>. However, second profiles <NUM> may also be present on both sides of each inner wall <NUM>. The inner walls <NUM> may comprise a plurality of connector plates (not shown) to which the second profiles <NUM> are welded, for instance. The second profiles <NUM> typically extend along the entire width of each inner wall <NUM>. The second profiles <NUM> may be T-shaped profiles, for instance. The second profiles <NUM> may be, for example, made of steel.

Typically, the marine foundation <NUM> comprises within each compartment <NUM> at least one stiffening element <NUM> extending from an inner side <NUM> of the perimeter wall to at least one inner wall <NUM>. In <FIG>, a plurality of stiffening elements <NUM> extend within each compartment <NUM> from a side <NUM> of the perimeter wall <NUM> to one inner wall <NUM>. The stiffening elements <NUM> provide stability to the shell structure and the inner walls <NUM> of the marine foundation <NUM>. The stiffening elements <NUM> may be, for example, in the form of pipes or hollow cylinders. The stiffening elements <NUM> may be, for example, made of steel. Typically, each stiffening element <NUM> is welded to a first profile <NUM> and a second profile <NUM>.

In <FIG>, a footprint of the base <NUM> is greater than a footprint of the cover <NUM>, i.e. a surface area of the base <NUM> is greater than a surface area of the cover <NUM>. Consequently, each side <NUM> of the perimeter wall <NUM> is inclined at an angle relative to the horizontal plane. Each side <NUM> of the perimeter wall <NUM> may be inclined at an angle to a horizontal plane in the range between <NUM>° and <NUM>°, for example <NUM>°. As a result, the marine foundation <NUM> is able to float even in very shallow waters when the cavity is filled with air or pressurized air.

The marine foundation <NUM> typically comprises at least one connector or valve (not shown) for filling at least a part of the cavity <NUM> with ballast such as (sea-) water or material capable of being pumped in order to install the floating marine foundation <NUM> at a desired installation site. Typically, ballast is then simultaneously guided into each of the compartments <NUM> of the marine foundation <NUM> for reaching final installation depth, i.e. the marine foundation <NUM> is gravity based. The marine foundation <NUM> further comprises at least one connector or valve configured to guide pressurized air into at least a part of the cavity <NUM>, preferably into each of the compartments <NUM>. In the semi-submerged state the cavity <NUM> of the marine foundation <NUM> may be completely filled with ballast such as water, water and pressurized air, or material capable of being pumped. Thus, forces are exerted against the forces created by the environment, in particular the water pressure, against the sides <NUM> of the perimeter wall <NUM>. Additionally, the marine foundation <NUM> typically comprises at least one connector or valve for emptying at least a part of the cavity <NUM> from ballast such as (sea-) water or material capable of being pumped. Water can also be removed using a pump and/or pressurized air in order to de-install the floating marine foundation <NUM>. Typically, ballast is then simultaneously guided out of each of the compartments <NUM> of the marine foundation <NUM> until the marine foundation <NUM> is floating again.

The form of the base <NUM> and/or the cover <NUM> may also be circular according to certain embodiments. In such a case, the shell structure typically has a circular cross-section. However, manufacturing a shell structure having a circular-cross section is more complex than providing a polygonal base <NUM> and a polygonal cover <NUM> separated by a plurality of planar sides <NUM> of the perimeter wall <NUM>.

In <FIG> a schematic cross-sectional view of a detail of a marine foundation in accordance with at least some embodiments of the present invention is illustrated. Six inner walls <NUM> are connected to a hollow structure <NUM>. The hollow structure <NUM> may comprise at least one ring <NUM> for stiffening the hollow structure <NUM>. The at least one stiffening ring <NUM> is typically arranged within the hollow structure <NUM>. The hollow structure <NUM> is typically arranged in the center of the polygonal base (not shown). The inner walls <NUM> are connected within the cavity to an outer surface <NUM> of the hollow structure <NUM>, thus forming a plurality of compartments <NUM>.

In <FIG> a schematic view of another detail of a marine foundation in accordance with at least some embodiments of the present invention is illustrated. A plate <NUM> or ring is arranged outside of the hollow structure <NUM>. The plate <NUM> is typically made of steel and welded to the hollow structure <NUM>. A concrete layer <NUM> is then made in such a way, that the plate <NUM> is embedded in or covered by the concrete layer <NUM>, i.e. a concrete layer surrounding the hollow structure <NUM> is made above the cover <NUM>. The cover <NUM> is further reinforced by several first beams <NUM>. The first beams <NUM> are typically arranged within the cavity <NUM> in horizontal direction. The first beams <NUM> are typically made of steel. Between the cover <NUM> and the first beams <NUM> an additional steel cover <NUM> may be arranged. Further, second beams <NUM> are integrated at an end of each inner wall. The second beams <NUM> extend from the base to the plate <NUM> in vertical direction. The second beams <NUM> are typically made of steel. The second beams <NUM> are welded to the hollow structure <NUM>, to the first beams <NUM>, to the steel cover <NUM> and to the plate <NUM>, i.e. the second beams <NUM> extend into the concrete layer <NUM>. Manufacturing takes place by welding the parts made of steel prior to forming the concrete cover <NUM> and the concrete layer <NUM>. The described construction avoids or at least reduces the risk of fatigue failure in the area of the opening in the cover <NUM>.

In <FIG> a schematic perspective view of a detail of a marine foundation <NUM> in accordance with at least some embodiments of the present invention is illustrated. The hollow structure <NUM> extends through an opening <NUM> in the cover <NUM>. The hollow structure is typically in the form of a hollow cylinder made of metal or a metal alloy, for example steel. The dimensions of the hollow structure <NUM> depend on various parameters such as water depth, height of the tide, intended use of the marine foundation <NUM> and size of the marine foundation <NUM> as such. An ice protector or ice shield <NUM> is connected to the hollow structure <NUM> outside of the cavity. The ice shield <NUM> may be, for example, in the form of a conical ring. The ice shield <NUM> is typically made of steel and welded to the hollow structure <NUM>. The position and the dimensions of the ice shield <NUM> depend on various parameters such as water depth, height of the tide, and size of the marine foundation <NUM> as such.

In <FIG> a schematic perspective view of an arrangement comprising an object <NUM> and a marine foundation <NUM> in accordance with at least some embodiments of the present invention is illustrated. The shown object <NUM> is a wind energy power plant. The object <NUM> is coupled to the marine foundation <NUM> at the upper end of the hollow structure <NUM> comprising a coupling section <NUM>. The coupling section <NUM> may, for example, comprise a flange for attachment of the object <NUM>.

In the semi-submerged state, the shell structure of the marine foundation <NUM> may be covered with soil, gravel and/or stones in order to provide further stability.

According to certain embodiments of the present invention, a wind energy power plant can be coupled to the marine foundation floating e.g. in a harbour prior to towing the combined unit including the marine foundation and the wind energy power plant to the installation site. The marine foundation <NUM> is configured to change its state from a floating state to a semi-submerged state and reverse. In the floating state the cover <NUM> and a part of the hollow structure <NUM> are located above the water surface. At the installation site, the combined unit is partially submerged into a semi-submerged state. In the semi-submerged state only a part of the hollow structure <NUM> is located above the water surface, i.e. the base <NUM>, the perimeter wall <NUM> and the cover <NUM> forming the shell structure are submerged completely below the water surface. After its lifespan, the combined unit can be de-installed by changing the state back into the floating state and towing the combined unit to a land-based de-installation site. Thus, heavy installation equipment is not required at the sea-based installation site and the wind energy power plant can be installed and de-installed cost-efficiently.

Claim 1:
A marine foundation (<NUM>) comprising:
- a planar base (<NUM>), a perimeter wall (<NUM>) and a cover (<NUM>) forming a shell structure having a cavity (<NUM>),
- a hollow structure (<NUM>) extending through an opening (<NUM>) in the cover (<NUM>) to the base (<NUM>),
- wherein within the cavity (<NUM>) a plurality of compartments (<NUM>) is formed,
- wherein the marine foundation (<NUM>) is configured to change from a floating state to a semi-submerged state by pumping of material capable of being pumped into the cavity (<NUM>),
- wherein the marine foundation (<NUM>) is configured to change from the semi-submerged state to the floating state by pumping of material capable of being pumped out of the cavity (<NUM>), and
- wherein in the floating state at least the cover (<NUM>) and a part of the hollow structure (<NUM>) are located above a water surface, and wherein in the semi-submerged state the base (<NUM>) is positioned on a seabed,
characterized in that
- the base (<NUM>) is polygonal,
- the cover (<NUM>) is polygonal and planar,
- the perimeter wall (<NUM>) has a plurality of planar sides (<NUM>) protruding from the polygonal base (<NUM>) to the polygonal cover (<NUM>),
- wherein the plurality of compartments (<NUM>) is formed by inner walls (<NUM>) extending from at least two edges (<NUM>) to the hollow structure (<NUM>), wherein each edge (<NUM>) is formed between two adjacent planar sides (<NUM>) of the perimeter wall (<NUM>), and
- wherein each planar side (<NUM>) of the perimeter wall (<NUM>) is inclined at an angle to the polygonal base (<NUM>) in a range between <NUM>° and <NUM>°.