WO2015136086A1

WO2015136086A1 - A quay structure, a quay arrangement and a method of installing such structure

Info

Publication number: WO2015136086A1
Application number: PCT/EP2015/055324
Authority: WO
Inventors: Gregers Kudsk
Original assignee: Apm Terminals Management Bv
Priority date: 2014-03-13
Filing date: 2015-03-13
Publication date: 2015-09-17

Abstract

A floating semi-submersible structure for providing a quay for berthing sea-going vessels, said structure comprising a barge (1) comprising a top platform (11) and one or more buoyancy chambers (12) for maintaining the upper surface of the barge above water level, one or more anchors (21, 30) for securing the barge to the seabed, wherein at least a part of said anchors are arranged to hold said upper surface stable and level under varying loads on the upper surface via a permanent tension load due to the buoyancy of the barge.

Description

A quay structure, a quay arrangement and a method of installing such structure

The present invention relates to a floating quay structure for providing a quay arrangement for berthing sea-going vessels, said structure comprising a barge having a top platform and one or more buoyancy chambers for maintaining the upper surface of the barge above water level, and securing the barge to the seabed preferable at or near a plurality of corners of said barge. The invention also concerns a method of installing such structure. From US 8,251 ,002 B2 a pontoon-type floating structure is known. Herein there is disclosed a platform with buoyancy chambers and which is secured to the seabed such that the upper deck of the platform is maintained above water level and to receive and support a load on the platform. In the US 8,251 ,002 there is disclosed that the platform could be used as a floating container terminal. This pontoon-type floating structure deals with avoiding deflection of the platform by providing a number of buoyancy chambers in the platform. As taught in US 8,251 ,002 by the design of very large floating structures it is intended to minimise wave induced motions of the platform. However, pontoon-type floating platforms are typically used on calm waters and when such pontoon-type floating platform is provided in large dimensions deflections of the platform is of concern.

A floating platform for deployment in shallow or deep waters is also known from US 2008/0038067 A1 . This platform comprises an array of hollow structural elements for dynamically ballasting the platform by locally adjusting the buoyancy of the structural elements depending on where the load on the platform is provided.

In CA1064334 a floating off-shore platform is described for extracting or processing gas. This platform is anchored to the seabed. The platform includes a submerged buoyancy units and an upper deck which is raised high above the water line. This makes such a platform unsuitable for efficient loading and unloading of cargo ships.

Further to the prior art structures, it is an object of the present invention to provide a stable floating quay structure, which is a stable operating environment for the cranes and the like for the provision of a floating quay structure. Standard berthing operations from quayside (i.e. typically ground level in a habour) is optimized for truck access to take containers to and from the site and cranes are optimized for reaching over the ship and access hatches and containers on deck. Accordingly, it is preferable that the height of the deck of quay is somewhere between 0.5 to 20 meters over the MSL (mean sea level), more preferably, between 1 -10 meters, such as between 1 -8m, such as between 2-6 meters, such as between 2-4 meters, such as between 3-4 meters.

This object is achieved by a floating semi-submersible structure for providing a quay for berthing sea-going vessels, said structure comprising a barge comprising a platform with an upper surface and one or more buoyancy chambers for maintaining the upper surface of the barge above water level, one or more anchors for securing the barge to the seabed, wherein one or more of said anchors are arranged to hold said upper surface stable and level under varying loads on the upper surface via a permanent tension load due to the buoyancy of the barge. In other words, the anchors in the subset are coupled to the seabed at one end and the barge at the other end in such way that the barge is submerged further than it would be without the tension load in the anchor, so that the buoyancy of the barge exerts a tensile pressure on the anchor. The phrases permanent tension, preload and pretension is in the context of the present invention taken to mean that during operation as a quay structure the object is under tension (which may vary, but remain positive) as long as the maximum load on the upper surface of the quay is not exceeded.

The quay structure fulfils the function of a floating quay platform and is anchored to the seabed by anchors and typically also anchoring systems preferably at each corner. Contrary to the floating quay structures cited above, the invention advantageously provides anchoring to the seabed applied to a floating structure for container operations and other quay operations which prevents the quay structure from moving due to variations in load on the quay structure or due to tidal water changes. As an alternative or in combination with placing anchors at the corners, the anchors may be distributed in various ways such as evenly distributed, along the sides, in rows along the length, at the ends and in the middle and combinations thereof. Fewer anchors may simplify installation whereas more anchors may better distribute the loads from the anchors over the barge and thus may allow for a less stiff barge. Depending on the soil conditions it may also be advantageous to install fewer larger anchors or install a higher number of smaller anchors. Advantageously it is realised that the barge may generally consist of three layers: an upper deck part, a lower section providing buoyancy and typically substantially completely submerged and a mid-section having low buoyancy relative to the volume between the upper and lower sections.

In order to establish access to the quay platform, a connection member is provided between the barge and the shore, said connection member having an upper surface adapted to vehicle transportation of cargo to and from the quay. Preferably, said connection member is a connection bridge having and floating structure and wherein said bridge is anchored to the seabed by one or more pillars and/or tension legs.

In some embodiments of the invention an anchoring system refers to one or more anchors providing vertically and horizontally stability to at least part of the barge. As described below, vertically and horizontally stability is in some embodiments achieved via a single pillar acting as anchor and installed and mounted to the barge so that during operation the pillar is under permanent tension due to the buoyancy of the barge, i.e. that pillar holds the barge down and restricts the barge from rising further out of the water. At the same time the pillar may provide transverse or horizontal stability by being coupled to the barge so that it restricts the transverse movements of the barge. In other embodiments, two or more anchors share the loads to provide the vertically and horizontally stability, such as a tension leg and a horizontal stabilising anchor, to form an anchoring system. Typically, the anchor(s) of an anchoring system are arranged to act in substantially the same point on the barge e.g. mounted in a common compartment, but may in principle be spaced from each other and even distributed differently. Anchoring systems of different types may also be applied to the same barge. An anchoring system is typically acting primarily on a section or part of the barge, such as when mounted in one of the corners. It is typically necessary to provide more than one anchoring system or anchoring points to provide stability to the entire barge. A stiffer construction of the barge and the coupling between barge and anchors may provide for the need for less anchoring, but will typically drive the cost of the system up. In some embodiments, the barge is fixed at one end to shore and in other embodiments the barge is fixed via anchors alone. The anchoring systems, typically at least in each of the corners of the barge, may comprise one or more components. Accordingly, the anchoring system may be in the form of tension legs in their common configuration, i.e. cables or chains secured to the seabed and/or a pillar, such as spud piles, driven into the seabed and/or in both cases acting as a tension leg and held tensioned by the buoyancy of the floating structure. In the following reference to a tension leg shall, unless otherwise clear, refer to a tension leg in its common form; however, with the proviso that, unless otherwise clear, this type of tension leg may be replaced by any type of anchor coupled to the seabed and the barge and under permanent tension due to buoyancy of the barge such as a pile arranged under permanent tension such as in fig. 13 and 14. In an embodiment where the anchoring systems comprise tension legs (particularly in their common form), a horizontal stabilising anchor, for instance in the form of pillars, also known as spud piles, are provided preferably at least in each corner to absorb the horizontal forces that the floating quay is subjected to. In some embodiments, the function of the horizontal anchor may be integrated with one or more of the tension legs e.g. by slanting one or more of the tension legs. In other embodiments, pillars are used for absorbing both vertical and horizontal forces as the pillars are installed on the seabed and the barge is mounted to the pillars (see e.g. fig. 13 and 14). In the preferred embodiment, the barge has a rectangular platform and the lower section with four corners and the anchoring system is arranged at least at the corners of said barge. The anchoring system pillars may be extended through the lower section of the structure or terminated in the lower section. In embodiments where the barge is sectioned in a lower, mid and upper section the pillers may also terminate in the mid- section and preferably in the upper section so that there is easy access from the top. In some embodiments the mid-section is at least partly formed by the pillars so that the pillers at least partly support the upper section (i.e. typically the platform deck). In other embodiments the upper section is supported on columns supported by the lower section. The pillers will typically extend through some or all of these columns (and/or terminate inside them) but may also extend to the upper section beside the columns.. As discussed in relation to Fig. 6-9 below having a relatively small volume of the midsection (when placed in the waterline) has the advantage of providing less variation in the total buoyancy of the barge as a function of tidal and/or wave variations.

Furthermore, it is is some embodiments advantageous for the mid-section to have a substantially constant cross section. In some embodiment the mid-section (extending from the lower section to the upper section) is arranged at MSL so that it extends from a position below the MSL to a position above MSL. In one embodiment the mid-section extends from more than 0.3 meters below MSL, such as more than 0.5 meters below MSL, such as more than 1 meter below MSL, such as more than 1 .5 meters below MSL, such as more than 2 meters below MSL, while at the same time less than 30 meters below MSL, such as less than 20 meters below MSL, such as less than 10 meters below MSL, such as less than 5 meters below MSL. In some embodiments the mid-section extends to at least 0.5 meters above MSL, such as at least 1 meter above MSL, such as at least 2 meters above MSL, such as at least 3 meters above MSL, such as at least 4 meters while at the same time less than 30 meters above MSL, such as less than 20 meters above MSL, such as less than 10 meters above MSL, such as less than 5 meters above MSL. In some embodiments the top of the med-section is arranged at at least the significant weight height over MHWS (mean height water spring) plus 10% or more, such 25% or more, such 50% or more, such as 100% or more, such 200% or more. The bottom is at least the level of the valley of the significant wave under LAT (lowest astronomical tide) minus 10% or more, such 25% or more, such 50% or more, such as 100% or more, such 200% or more. To provide a relatively small variation in submerged volume as the water level varies the area of the horisontal cross section (such as the sum of cross sections of columns forming mid- section) of the mid-section should be small. In some cases the area of the horisontal cross section is less than 50% of the area of the upper surface, such as less than 40%, such as less than 30%, such as less than 20%, such as preferably less than 10%, such as less than 5% and even more preferably less than 3%. As mentioned above, in accordance with an embodiment of the invention, each of said anchoring systems comprise a pillar which is driven into the seabed. Other methods may be applied to install such pillars in the seabed, such as pre-drilling a hole for the pillar and cementing it in place. This proves an advantageous solution since this way of installing the barge does not require pre-installations on the seabed. If the seabed is soft or if it is found necessary to further secure the pillar to the seabed, the pillar may be grouted in the seabed.

In an embodiment of the invention, each of said anchoring systems comprise at least one tension leg with at least one mooring line secured to the seabed and tensioned due to the buoyancy of the barge, and at least one horizontal stabilising anchor connecting the barge to the seabed. It is found advantageous to use the tension leg technology applied to a floating structure for container operations and other quay operations. The horizontal stabilising anchor, for instance in the form of pillars, also known as spud piles, are provided at each corner to absorb the horizontal forces that the floating quay is subjected to. In some embodiments, the function of the horizontal anchor may be integrated with one or more of the tension legs e.g. by slanting one or more of the tension legs.

In this embodiment it is found advantageous to provide the combination of horizontal stabilising anchor, such as spud piles and/or anchors with chains, to control horizontal movements and tension legs to control the level. When installed, the tension in the tension legs is provided by the buoyancy of the barge and is therefore reduced by an increase in operating loads on the barge. However, by providing sufficient tension in the tension legs (causing the barge to float lower than it would with no tension legs and increasing the buoyancy force) the barge will be vertically stationary for loads less than buoyancy. Hereby roll and pitch of the barge in the water is prevented while allowing variations in operating loads on the barge, exerted by vessels, cranes and vehicles as well as weather influences. In the present context a tension leg anchor is taken to mean an anchor arrangement providing sufficient down-force to provide a stable deck (i.e. the top surface of the barge) while supporting the variable loads associated with such operations. The anchor is connected via a flexible cable, wire or chain between a fixed point on the seabed (typically a pile driven into the seabed) and the barge. In some embodiments, the tension legs are therefore arranged to lower the deck more than 0.5 m relative to the steady state level without tension in the tension legs, such as more than 1 m, such as more than 1 .5 m, such as more than 2 m, such as more than 2.5 m, such as more than 3 m, such as more than 4 m. In some embodiments, the tension legs are arranged to lower the deck more than 10% of the total height of the barge relative to the steady state level without tension in the tension legs, such as more than 15%, such as more than 20%, such as more than 25%, such as more than 30%, such as more than 50%. This allow for a steady state level of the barge with variable loads on the platform deck, such as cranes and other equipment of up to 500 kN/m² or more, such as 1000 kN/m² or more, such as 2000 kN/m² or more, such as 5000 kN/m² or more, or up to 10,000 kN/m². In one embodiment, the at least one horizontal stabilising anchor of each corner comprises pillars, such as spud piles. Accordingly, the at least one horizontal stabilising anchor of each corner comprises one or more piles mountable to the seabed underneath the barge.

In another embodiment, a plurality of anchors are provided at each corner, each comprising an inclined anchor chains between the corner of the barge and anchor point of the anchor in the seabed. The alternatives of using either spud piles or anchors and chains can be two separate solutions or may be used in combination depending on the circumstances.

Preferably, the barge is provided with a ballast arrangement for controlling the buoyancy of the barge. In particular, said ballast arrangement may preferably comprise a plurality of ballast tanks and optionally a ballast control system for supplying and discharging water to and from said ballast tanks. One application of such a ballast arrangement allows optimizing the tension force in the anchors under varying temperature conditions. By controlling or arranging the ballast in relation to the buoyancy of the barge the tension in each tension leg is also ensured to be present irrespective of the water level, which may vary due to the tide, as well as the load on the deck, which may also vary depending on the activities on the quay. The buoyance, ballast and tension of the tension legs are arranged so that the tension legs are kept tensioned at all times. The mooring lines of the tension legs are typically wires, but could alternatively also be chains or spud piles. Chains are in some embodiments preferable as they are often cheaper and provides for simple interlocking (e.g. using a chain stop) so that chain can be easily locked to the barge during installation. In a preferred embodiment, a multiple of tension legs are arranged at each corner. The advantage of a multiple of lines at each corner is that the tension at each cable (or chain) is reduced. In a preferred embodiment multiple wires or anchors are applied to provide redundancy.

In one embodiment of the invention, the barge is made of steel. However, by the invention it is realised that the barge can also be made of concrete or be made as a structure which is a combination of steel and concrete. Preferably each of the anchoring systems of the barge are provided with an anchor mounting receiving compartment for receiving some components of the anchoring system, such as tension leg mooring lines and a fixation compartment for receiving the horizontal stabilising anchors. The corner design of the barge for anchoring the tension legs to the barge is designed so that the mooring lines, such as tension cables, are received in a corner compartment and mounted to the barge. Such compartments may also be installed at other areas of the barge as an alternative or supplement e.g. to distribute the down-force on the barge instead of or as a supplement to the

arrangements in the corners.

Advantageously, the barge is provided with equipment on an upper deck for enabling processing of cargo to or from one or more vessels moored to the structure, such as mobile harbour cranes (MHCs) of up to 625 1 gross weight and/or for rail mounted ship- to-shore (STS) gantry cranes. Accordingly, in some embodiments the upper deck comprises rails for cranes. Such cranes typically weigh more than 500 tons but less than 5000 tons, such as between 500 tons and 4000 tons, such as between 1000 tons and 4000 tons, such as between 1000 tons and 3500 tons, such as between 1000 tons and 3000 tons, such as between 500 tons and 2500 tons, such as between 1000 tons and 2000 tons. In some embodiments the cranes (mobile or rail mounted) are arranged to with an upper lifting capacity at the ropes lifting to and from the ship between 80 tons and 300 tons, such as between 80 tons and 200 tons. Mobile and rail mounted habour cranes are distinguishable from marine cranes, tower cranes and knuckle-boom cranes typically applied in offshore structures where loads are lifting to and from the deck residing above a supply vessel. The floating quay comprising one or more barges allows the free movement of cranes for container operations or other equipment.

Accordingly, in accordance with a second aspect of the invention, there is provided a quay arrangement comprising a plurality of sections of quay structures according to the first aspect described above arranged abutting each other for forming a quay for berthing of sea-going vessels. Preferably, in the quay arrangement, one or more of the tension legs or anchors may be arranged to pull the sections towards each other.

In some embodiments the invention relates to barge(s) constructed as described in comination with an access bridge coupling the barge to a quay side on shore or another fixed structure, preferably an access bridge suitable for allowing semi-truck to transport cargo containers to and from the barge. The invention also related to a method of installing such a system of one or more barges and an access bridge. A multiple of platform barges hereby form quay sections arranged in a row to form a floating quay. The number of barges can be chosen in accordance with the desired length of the quay. One or more of the tension legs may be provided with inclination to drag the sections, i.e. two neighbouring barges together. The deck (i.e. its upper flat surface) of the barge is preferably substantially rectangular which allows it to be substantially parallel to a ship moored to the quay and allows more than one barge to be abutted to increase the length or the width. However, other shapes are also envisioned, such as round, semi-circles and squares and as well as combinations thereof. In some embodiments, the barge is longer than 50 m such as longer than 75 m, such as longer than 100 m, such as longer than 125 m. In some embodiments, the barge is furthermore more than 20 m wide, such as more than 30 m wide, such as more than 40 m wide, such as more than 50 m wide, such as more than 60 m wide, such as more than 70 m wide, such as more than 80 m wide, such as more than 90 m wide. The barge is preferably sufficiently high that a suitable deck height above the water can be provided. At the same time, it is often preferable that, when installed, the lower surface of the barge is relatively close to the seabed because this can allow a more efficient functioning of the horizontal anchors. When the horizontal anchor is in the form of anchor chain (or cable) to an anchor on the seabed, the chain with a lower spacing between barge and seabed may allow the chain to lay more horizontal which typically makes it more efficient. In some embodiments, the chain of one or more of the horizontal anchors is fixed to the barge above the water level, follows a substantially vertical direction to the bottom of the barge and tapers to horizontal. In some embodiments, the chain transfers at least some (such as all) of the horizontal forces to the bottom of the barge. On the other hand, if the spacing between seabed and barge becomes too narrow there is a risk that the water flow below the barge will be so constricted that the flow causes a substantial down-force on the barge. Accordingly, in some embodiments, the barge is arranged so that, when installed, the spacing between seabed and barge is more than 0.5 m, such as more than 1 m, such as more than 1 .5 m, such as more than 2 m, such as more than 3 m, such as more than 4 m. In some embodiments, the barge is more than 2 m high, such as more than 4 m, such as more than 6 m, such as more than 8 m, such as more than 10 m, such as more than 12 m. In some embodiments, the barge is between 2 and 25 m high, such as between 3 and 20 m, such as between 5 and 20 m, such as between 5 and 15 m, such as between 7 and 15 m, such as between 7 m and 13 m.

The floating quay for vessels, in particular container vessels, are preferably designed for loading and discharging activities only as the floating quay arrangement is installed such that it extends from a shoreline, such as an existing quay and into the port basin or sea.

In a third aspect of the invention, there is provided a method of installing a quay structure in a maritime environment, preferably on shallow water, said method comprising:

- providing a barge from off-site to a predetermined position,

- mounting at least one pillar at the predetermined positions by driving, or otherwise installing, the pillars into the seabed underneath the future position of the barge.

Installing a pillar through the barge has the advantage that the barge may provide its own work platform for installation and installation equipment may be sailed to the site on the barge.

This method of installing a floating quay on-site is quick and simple. The barges may be built and equipped off-site and then transported to the quay site.

In an embodiment, the seabed may be prepared for the receipt of the barge or barges by mounting the anchoring structures for the tension legs. Optionally, preparing the seabed by mounting tension leg anchors when needed for receiving mooring towlines at predetermined positions for embodiments where these are needed. For

embodiments where the functions of provided vertical and horizontal stability are integrated into a pillar such preparation may not be needed. The barge is provided from off-site to a predetermined position with corners corresponding to the tension leg anchors. The barge may be positioned and the mooring towlines of the tension legs of the corners of the barge are then connected to the corresponding tension leg anchors on the seabed. The method may also involve the step of mounting at least one pillar at the predetermined positions by driving (or otherwise installing) the pillars into the seabed underneath the barge or installation of at least one anchor in the sea bed to control the horizontal motions of the barge. The method preferably further comprises the steps of submerging or semi-submerging the barge by controlling the buoyancy, loading the barge, ballasting, providing tension to one or more piles installed; and after the step of connecting the mooring towlines, and lifting the barge by establishing buoyancy to position the barge at a predetermined level above the water level and thereby tensioning the tension leg towlines;

Preferably, the barge is provided with equipment on the platform, such as mobile harbour cranes or the like, pre-installed for enabling processing of cargo to or from one or more vessels moored to the structure. In a preferred embodiment, the mooring towlines are pre-installed on the tension leg anchors on the seabed before providing the barge on the mounting site. Alternatively, the mooring towlines are pre-installed on the barge. In accordance with the actual coastal conditions, the seabed, etc. on the installation site, the quay structures may be prepared with the pre-installations deemed most suitable.

The quay structure according to the invention is preferably mounted on shallow water in a coastal region extending into the sea from a shoreline. In some embodiments, shallow water is taken to mean a water depth of less than 200 m, or even less than 100 m or even further less than 50 m, such as less than 40 m, such as less than 30 m, such as less than 20 m, such as less than 10 m. However, shallow water is typically deeper than 2 m, such as deeper than 5 m, such as deeper than 9 m.

In the context of the present invention, by the term "a barge" is meant a long, large vessel typically having no keel, but typically having a deck that is above the water line for carrying freight and which is generally unpowered and towable or pushable by another craft. However, by the invention it is realised that the barge may have an upper platform deck and a floating structure which may or may not include a keel.

In the context of the present invention, by the terms "a berth" or "berthing" are meant a space for a ship to dock or anchor or the act of docking a ship, i.e. a sea-going vessel. The tensions legs are not "just for mooring", but rather arranged to absorb the changes in the live loads to allow these live (movable/variable) loads to vary greatly without the barge moving.

Other features of the invention which may be advantageous in certain circumstances include active pumping ballasting or dynamic ballasting, such as opening closing valves, where active pumping or dynamic refers to a system that is active during operation. This may result in less tension on the anchoring pillars and/or cables. In some embodiments, active or dynamic ballasting further comprises one or more sensors and control system to guide the system. In some embodiments, the active or dynamic systems may control the ballast according to the load and/or the expected load on the barge. In some embodiments, the active pumping and/or dynamic system is arranged to control the transverse distribution of ballast water, such as in response to the habour cranes moving along a berthing vessel. Ballast water is typically moved away from the position of the crane to even the load over the barge. In some embodiments, this is controlled by load sensors and/or by sensor or control system in response to the position of the cranes. It may also be advantageous to dimension the barge such that it is closer to the seabed. This may make the vertical anchors more effective. In case of vertical anchor cables, these may be connected in a dry room inside the barge above the water level, guided to the bottom of the barge and extend vertically (after tapering a couple of meters) along the seabed.

In an embodiment using tension legs with chains, the barge may advantageously be designed with dry hook up rooms for the chains. Such hook up room may be provided with openings to below. This facilitates the installation of the barge when anchoring it to the seabed.

In order to achieve redundancy in the anchoring systems, multiple cables, chains or pillars may be provided for each point of anchoring, such as at each corner.

Also it is realised that "Coffer dam" ballast chambers may be provided with one or more tanks inside the compartment. The barge design with the features mentioned above may be found advantageous in relation to safety in relation to puncture of the structure.

In the following the invention is described in more details with reference to the accompanying drawings, in which:

Fig. 1 is a schematic top view of a quay arrangement comprising a plurality of sections of quay structures;

Fig. 2 is a schematic cross-sectional detailed view of a first embodiment of the

invention;

Fig. 3 is a schematic cross-sectional detailed view of a second embodiment of the invention;

Fig. 4 is a schematic cross-sectional detailed view of a third embodiment of the

invention;

Fig. 5 is a schematic cross-sectional detailed view of a fourth embodiment of the

invention;

Fig. 6 is a perspective illustration of a floating quay arrangement according to an

embodiment of the invention;

Fig. 7 is a perspective view of a barge according to another embodiment of the

invention;

Figs. 8 and 9 are cross-sectional view of A-A and B-B of fig. 8;

Fig. 10 illustrates the forces acting on a barge according to the invention;

Fig. 1 1 is principal illustration of the movements that may be caused by the forces acting on the barge;

Fig. 12 shows schematic cross-sectional views of the barge illustrating effects acting on the barge; and

Fig. 13 is a schematic cross-sectional detailed view of a fifth embodiment of the

invention;

Fig. 14 is a schematic cross-sectional detailed view of a sixth embodiment of the

invention; and

Fig. 15 is a schematic sectional top view of the pillar fixation in fig. 14,

Fig. 16 is a schematic perspective view of a barge according to a currently preferred embodiment of the invention,

Fig. 17 is the same embodiment as in fig. 16 but from a different perspective, Fig. 18 is a schematic cross-sectional view of the barge in figs. 16 and 17,

Fig. 19 is a detailed view thereof,

Fig. 20 is a schematic top view of a connecting bridge between the barge and the shore line,

Fig. 21 is a schematic cross-sectional side view thereof,

Fig. 22 is a schematic view of a cross-section orthogonally to the direction of the

connecting bridge, and

Fig. 23 is a schematic perspective of the connecting bridge. As shown in fig. 1 , a group of barges 1 are linked together to form a floating quay for berthing of a vessel 8, such as container and other types of vessels. Each barge 1 is preferably between 50 and 150 m, but even up to 450 m long or more and 20 and 60 and up 100 m wide or more. Accordingly, in one embodiment the barge is 50 m or longer, such as 70 m or longer, such as 90m or longer, such as 130m or longer, such as 150m or longer, such as 200 m or longer, such as 230 m or longer, such as 250 m or longer, such as 300 m or longer, such as 350 m or longer, such as 400 m or longer. The depth of each barge 1 is preferably 4 to 15 m, such as 4 to 10 meters, such as 4 to 7 meters. The barges 1 are arranged to float in the sea 7, preferably in the port basin next to the shore 6, such as an existing quay. The barges 1 are anchored to the seabed 9 (see figs. 2-5) by a tension legs arrangement 2 and a spud pile 3 at each corner. At the barge 1 closest to the shore 6, the quay is provided with an access bridge 5. Depending on shore conditions the access bridge can in general be between 1 to a 1000 meters or more. The bridge may or may not be supported by piles and/or other anchors similar to the barge but will typically be hinged to the quayside and the barge at either end. The quay formed by the barges 1 is also the working area for stevedoring activities. This implies that on the upper surfaces of the barges 1 which form a deck 1 1 there is provided equipment 10 on the deck 1 1 for enabling loading and unloading of cargo to or from one or more vessels 8 moored to the quay. Such equipment 10 may include mobile harbour cranes, reach stackers and trucks with trailers. Storage and/or processing of the cargo usually will take place on another location on shore.

In some embodiments, the quay arrangement according to the invention is in use similar to conventional quays, with bollards (not shown) typically having max. 20 m intervals and at least 100 tons capacity. In some embodiments, fenders (not shown) are included. These are typically max. 2 m wide cone or cylinder type fenders, suspended from the side of the quay wall with chains.

As mentioned above, each barge 1 is being held in position by spud piles 3 in each corner, which lead through the structure (see figs. 2-5). The opening of the spud pile hole is covered to create a uniform deck to operate. The spud piles or alternatively chains with anchors absorb all horizontal forces exerted on the quay structure, including those of the vessels moored against the structure. The design of the piles and the anchoring structure 21 of the tension legs 2 may depend on the soil conditions. In figs. 2 to 5, four embodiments of the anchoring assembly at the corners 4 of the barge 1 are shown.

The barges 1 are provided with ballast tanks in compartments 12 so that the buoyancy of the barge 1 is controlled and ensured to tension the tension legs 2 even at low sea level 71 and high load on the deck 1 1 . This provides stability to the barge 1 and consequently to the quay.

This operational stability is ensured by creating a pre-load in the structure through the one or more tension legs 2 in each corner 4 in addition to the spud piles 3 or anchor chains. The tension in the tension legs 2 will be up to 20,000-60,000 kN per corner. This creates a level operating deck 1 1 , which will remain stable as the forces on the quay structure (deriving from sources such as vessels, cranes, vehicles, weather and waves) vary. The loads may vary from nothing up to 500 kN/m² or more, such as 1 ,000 kN/m² or more, such as 2,000 kN/m² or more, such as 5,000 kN/m² or more, such as 10,000 kN/m². The deck can also be fitted with rails for rail mounted cranes.

The structure of each barge 1 is divided in various compartments 12. This design of the barges 1 with such compartments 12 and with vertical inner walls 13 serve the purposes of providing structural strength, guiding of forces from the equipment 10, such as crane rails and propping pads, ballasting the barge 1 and also provides a buffer against vessel collisions.

The barge 1 is designed with a platform for operation with mobile harbour cranes (MHCs) of up to 625 1 gross weight and/or for rail mounted ship-to-shore gantry cranes (STSs). In the case of mobile harbour cranes, the platform is stable enough to allow free movement of the cranes over the platform. In the case of ship-to-shore gantry cranes, these are positioned on rails, under which bulkheads in the platform are constructed. The equipment on the deck 1 1 , such as the ship-to-shore gantry cranes or the like, is preferably pre-installed at the yard building the barge 1 .

The deck of the platforms is typically paved. The deck 1 1 may be designed to withhold a uniformly distributed load of at least 30 kN/m², and wheel forces of 275 kN, and propping pad forces of at least 400 kN/m² in designated places, which are typical requirements for present loading equipment. Higher values are expected in the future. The load requirements for a platform are 275 kN per tire or higher, or 1 150 kN per axle or higher, while propping pads exert forces up to 400 kN per m²or more. The tension in the anchors (tension legs/pillars) is typically dimensioned accordingly in some embodiments taking the ballasting system into account.

As shown in fig. 1 and fig. 6, the platforms 1 are connected to each other by suitable means, such as braces or hinges, and the gap will be covered by a box and/or driving plates for free movement of vehicles and cranes.

The connection 5 to the shore 6 is for instance made by ramps. For this, the side of the barge 1 closest to the shore 6 will be within a reasonable span and angle from the shore 6, to allow mobile harbour cranes to drive over from the shore quay to the floating quay. As an example of a connection 5, shelf ferry ramps could be used.

The floating quay according to the invention will be operated as alternative to a conventional port quay. Therefore, similar environmental conditions apply as to conventional quays. The depth of the water in which the floating quay operates can vary between 5 and 100 m.

In fig. 1 , there is shown a first embodiment of the invention where the anchoring system comprises one tension leg provided at each corner 4. Three barges 1 are provided in a row to form a floating quay extending from the shore, such as an existing quay 6 and into the sea 7, such as the port basin. A vessel 8, such as a container vessel can be received along the quay and loaded or unloaded by harbour equipment 10, such as mobile harbour cranes 10, provided on the barges 1 forming the quay. Between the barge 1 closest to the shore 6 and the shore 6 an access bridge 5 is provided.

At each corner 4 of the barges 1 anchoring arrangements 2, 3 are provided. In the shown embodiment, one tension leg 2 is provided at each corner 4 as well as one horizontal stabilising anchor 3 in the form of a pillar 30 (see figs. 2-4 and 6).

In figs. 2-5, four embodiments of the anchoring system arrangement are shown. Fig. 2 shows a cross-sectional schematic view of the anchoring system of a barge 1 . The barge 1 is semi-submerged in the water 7 and anchored to the seabed 9. The barge 1 has an upper deck 1 1 and is provided with a series of ballast compartments 12 divided by internal walls 13. Not shown is the ballast control arrangement for pumping water into or out of the ballast compartments 12 for controlling the buoyancy of the barge 1 during transport, installation, and when installed, so that the deck 1 1 is firmly at a predetermined height above the water level 71 at all times. According to this first embodiment, the anchoring system is provided with one tension leg 2 and a horizontal stabilising anchor 3 in the form of a pillar 30, which is driven into the seabed 9. The tension leg 2 has a tension cable 20 mounted to a tension leg anchor 21 on the seabed 9. The tension leg cable 20 is secured to the barge 1 at the corner in a tubular mounting compartment 22 with retention means 23. The tension cable 20 may be tensioned during the installation of the tension leg 2 by hydraulic equipment or the like operated on the deck 1 1 and after installation the tension leg mounting compartment 22 may be closed. Similarly, an anchoring compartment 33 is provided for the horizontal stabilising anchor 3. Herein, the top of the pillars 30 is secured to the barge 1 by suitable mounting means.

In fig. 3 there is shown a second embodiment, which is similar to the first embodiment of fig. 2, but with two tension leg cables 20 mounted in each tension leg compartment 22 in which each cable 20 is secured by individual retention means 23. In a variant of this embodiment, three or more tension legs 2 could be arranged at each corner 4 and/or in other positions along the barge. Particularly for longer barges it may be preferable to have a distribution of anchors in order to provide lateral and horizontal stiffness, such as near the ends and middle. The tension legs 2 are in this second embodiment arranged in a closest corner compartment 42. In an alternative third embodiment shown in fig. 4, the tension legs 2 are arranged in an open corner arrangement 41 , where the retention means 23 are provided with a common anchor plate 24 shared by both (or all) the cables 20. In a fourth embodiment of the corner arrangement, as shown in fig. 5, there is provided an open corner compartment 41 with one tension leg 2 similar to the tension leg arrangements 2 described above, but instead of the horizontal stabilising anchoring arrangement 3 being one or more pillars 30 as shown in figs. 2-4, anchor chains 31 are used. The anchor chains 31 are secured to the seabed by anchors 32 and in the open corner compartment 41 an anchor retention plate 34 is provided for mounting the anchor chains 31 to the barge 1 . In the embodiment shown in fig. 5, three anchor chains 31 are provided. However, a plurality of anchor chains 31 could be provided at each corner and/or at one or more other locations along the barge depending on the actual circumstances, such as the type of seabed 9, coast conditions, tidal waves, etc., in order to ensure the barge 1 is firmly stabilised when installed.

In fig. 6 another embodiment is shown with a tension leg arrangement 2 comprising three tension cables 20 individually secured to an anchoring section 21 in the seabed and two pillars 30 at each corner 4.

As shown in fig. 6, the cross-section of the barge 1 can be provided with a flat upper deck 1 1 and buoyancy compartments 12 along each side of the barge 1 and with a groove-like section in the centre of the bottom of the barge 1 . One of the advantages by the present invention is that the preparation of a harbour quay can take place off-site so that an existing quay can be kept operational while the barges 1 are being prepared at a shipyard elsewhere. The installation method at the site then may include preparing the seabed by mounting tension leg anchors 21 for receiving tension leg cables 20 at predetermined positions. The barge 1 is then provided from off-site to the installation site and positioned in a predetermined position with its corners 4 corresponding to the tension leg anchors 21 . The tension leg cables 20 are then connected to the corners 4 of the barge 1 to the corresponding tension leg anchors 21 and the pillars 30 are mounted by driving (or otherwise installing) the pillars 30 into the seabed underneath the barge 1 . Accordingly, the seabed 9 may be prepared for the receipt of the barge 1 or barges 1 by mounting the anchoring structures 21 for the tension legs 2 in advance.

When positioning the barge 1 , the barge 1 is semi-submerged to a low position in the water by controlling the buoyancy thereof. After the connection of the tension leg cables 20, the barge 1 is then lifted up in the water by establishing buoyancy so that the barge 1 is positioned at the predetermined level above the water level 71 and so that the tension leg cables 20 are provided with the predetermined tension stress. Thereafter the pillars 30 may be driven into the seabed and fixed to the barge 1 .

Further to fig. 6, fig. 7 shows the barge 1 with the flat upper deck 1 1 and with the two side portions 1 A and opening 1 B in the centre of the lower side of the barge 1 . At the corners and also at the middle sides of the barge 1 , anchoring arrangements 4 are arranged. In the side portions 1 A the ballasting tanks 12 are arranged. This middle section 1 B extends longitudinally and as also shown in figs. 8 and 9 the lower side of this middle section 1 B will not be submerged. As illustrated by this example, the barge generally consists of three layers: an upper deck part, a lower section providing buoyancy and typically substantially completely submerged and a mid-section having low buoyancy relative to the volume between the upper and lower sections. Lower section providing buoyancy is in one embodiment less than 50% of the total volume of the barge, such as less than 40% of the total volume, such as less than 30% of the total volume, such as less than 20% of the total volume, such as less than 10% of the total volume, such as less than 5% of the total volume. The mid-section is in one embodiment formed by a plurality of pillars supporting the deck section on the lower section. This structure has the effect that variations in the tension on the anchors due to tide and waves are reduced because the mid-section contributes with a relatively small degree of buoyancy. To further reduce these variations the columns may be made open to the sea. This design provides a catamaran-like barge structure where the side portion 1 A can be said to comprise columns surrounding each of the anchoring arrangements and supporting the deck on top of pontoons 1 A-1 stretching the length of the barge and forming the lower surface of the barge. The pontoon 1 A-1 is formed via the openings to the 1 A-2 middle section 1 B. The pontoons 1 A-1 is intended to be submerged when the barge installed similar to a semi-submersible drilling rig. Further to the opening below middle section 1 B this reduces the water plane area to the columns which in turn reduces the variation in buoyancy when and if the water rises and falls due to tide variation or waves. This means that the tension legs can be reduced to consider less of the variation in buoyancy and more the variation in deck loads. In some embodiments, tensions legs are preferably provided in all columns, in this case 6 columns. If the columns, as here, are made open to the sea to accommodate the anchors and tension legs, the ballast surrounding the column is preferably reduced or omitted. As shown in the figs. 8 and 9, which are sections A-A and B-B, respectively, of fig. 8, the ballast tanks 12 providing the buoyancy are provided below the sea level 71 irrespective of whether the sea level is at high tide 71 ' or low tide 71 ".

Fig. 8 shows the section A-A along the anchoring compartment 41 . In fig. 9 section B-B shows the design of the side portions 1 A and the position of the ballast tanks 12 below the water line 71 , where the "T" represents the difference between the low tide 71 " and the high tide 71 '.

As an alternative or supplement to the cut-out below the middle section 1 B and/or the openings 1 A- 2 one or more ballast tanks may be made open to the sea and/or provide an active ballasting system where pumps can adjust the amount of ballast and/or valves can open or close the access to the sea. Although, this may come with the disadvantage of adding further complexity and enclosed spaces may become contaminated by dirt and growth which may eventually block the water flow, openings will typically have the advantage of reducing the materials requirement and may therefore reduce the cost of the construction.

In some embodiments, the problem of contamination of an active ballasting system is at least partially circumvented by having the water intake at a higher position and the water outlet at a lower position. This may allow the water intake to begin as the tide rises and water drainage to begin with the falling tide. In some embodiments, this is at least partially controlled by active valves so that the amount of ballast can be more accurately controlled. With reference to fig. 10, the design of the semi-submerged structure according to the invention has a number of features to compensate external forces with these effects:

• Weather (wind, waves, current): roll, heave, pitch, yaw, sway, surge

· Vessels (push against fenders, bollard pull): sway, surge, roll

• Crane static load: roll, pitch, heave

• Crane dynamic loads (driving, slewing, luffing, hoisting with and without live loads): roll, yaw, pitch, sway

• Tides: heave

Furthermore, referring also to fig. 1 1 to control the shown degrees of freedom as well as sagging and hogging effects of the structure the invention (see fig. 12) has the following features:

• Heave, caused by

o Weather: tension legs

o Crane static loads: ballasting

o Tides: combination of ballasting and tension legs

• Sway: horizontal anchors or spud-piles

• Surge: horizontal anchors or spud-piles

· Pitch, caused by:

o Weather: tension legs

o Crane static loads: combination of ballasting and tension legs o Crane dynamic loads: tension legs

• Roll, caused by:

o Weather: tension legs

• Roll: ballasting and tension legs

• Yaw: horizontal anchors or spud-piles

· Sagging and hogging: structural rigidity and ballasting

A combination of ballasting and tension legs is used to keep the forces in the tension legs low, which has a positive effect on lifetime, safety redundancy and costs. A fifth embodiment of the invention is shown in fig. 13. At each corner 4 of the barge 1 , a pillar 30 is driven into the seabed 9. At the corner 4 a hatch 44 is provided on the platform deck 1 1 . Through this hatch 44, the corner arrangement can be accessed and the pillar 30 can be inserted and mounted. The pillar 30 can be driven into the seabed 9 by suitable equipment (not shown) provided on the platform 1 1 while the barge 1 is floating in the sea 7. In order to ensure the pillar 30 is firmly secured to the seabed, grouting may be used. When the pillar 30 is mounted in the seabed 9 the barge 1 and pillar 30 are fixed to each other. The top of the pillar 30 is preferably cut off at a predetermined height relative to the barge 1 and a pillar top 301 is then welded 303 onto the pillar 30. This predetermined height thereby defines the water level at the quay. The pillar top 301 is provided with a number of side flanges 304, preferably evenly distributed around the pillar 30. Between the side flanges 304 and the anchoring plate 34, adjustment members 302 are provided. The adjustment members 302 could be hydraulic cylinders or mechanically operated linear actuators. Hereby, the level of the barge 1 in the water 7 may be adjusted relative to the water line 71 . When the pillar 30 is installed the barge 1 may be ballasted to the desired level in the water (or otherwise made to submerge further, such as by loading or pulling on pillars 30) and the adjustment members 302 are installed and adjusted to the predetermined length. The barge 1 is then unballasted e.g. by removing some or all of the ballast water in the buoyancy chambers 12 to increase the buoyancy of the barge 1 and thereby create the permanent tension in the pillar 30 so that it is ensured that the barge 1 will remain in a stationary position irrespective of the deck load and any changes in water level. With reference to figs. 14 and 15, a sixth embodiment of the invention is shown. Like in the fifth embodiment a pillar 30 is driven into the seabed 9 at each corner 4 of the barge 1 . At the corner 4, a hatch 44 is provided on the platform deck 1 1 . Through this hatch 44, the corner arrangement can be accessed and the pillar 30 can be inserted and mounted. The pillar 30 can be driven into the seabed 9 by suitable equipment (not shown) provided on the platform 1 1 while the barge 1 is floating in the sea 7. The pillars 30 may be grouted to ensure the fixation of the pillars to the seabed. The barge 1 is then lowered in the water by ballasting the barge 1 or otherwise forcing it down in the water. When the pillar 30 is mounted in the seabed 9 the barge 1 and pillar 30 are fixed to each other. The top of the pillar 30 is preferably cut off at a predetermined height relative to the barge 1 and a pillar fixation sleeve 31 1 is then welded 303 onto the top of the pillar 30. The pillar fixation sleeve 31 1 is provided as a concentric ring structure around the top portion of the pillar 30. At the lower portion of the fixation sleeve 31 1 , the fixation support 31 1 is provided with a number of side flanges 304, preferably evenly distributed annularly around the ring sleeve 31 1 . Chains 309 are mounted to the side flanges 304. These chains 309 are at the top secured to the anchoring plate 34 via chain stoppers 310.

The chains 309 are adjusted in length so that when the barge 1 is unloaded the chains 309 are tensioned. When the platform 1 1 of the barge 1 is loaded and/or the water level drops, the tension of the chains will increase, but the level of the platform of the barge remains stationary. Unlike the fifth embodiment of fig. 13, the pillar 30 itself is loaded with compression forces as it is the chains that absorb tension forces.

When securing anchor blocks for tension legs and/or pillars to the seabed, it is by the invention realised that the foundation may be strengthened by grouting to support the floating quay structure. The grouting may be pressure grouting involving the injection of a grout material into generally isolated pore or void space into the seabed.

In figures 16-19, a currently preferred embodiment of the invention is shown. The floating quay is made of a series of barges 1 forming a floating structure extending from a shore line 6 (see also fig. 20). The barge 1 comprises an upper deck 1 1 on which gantry cranes and similar equipment 10 may be provided. Furthermore, the barge 1 comprises a lower section 1 ', which is fully submerged, and which preferably comprises buoyancy chambers, corridors, trim tanks and engine rooms. The trim tanks are mostly used for transit of the barge from its point of production to the installation site. In the engine rooms installations, such as pumps and the like, may preferably be installed for controlling the water to ballast and trim the barge during transit and during operation. The lower section 1 ' is preferably a box-like shape which typically simplifies

construction.

The platform 1 1 is mounted on top of the lower section 1 ' and supported by an array of pillars 30 (see details in fig. 19). Preferably, the platform supporting pillars 30 are axially aligned and are upwards extensions of the anchoring pillars 30 anchoring the lower section 1 ' and thereby the barge 1 to the seabed 9. The platform 1 1 is hereby kept at a predetermined level above the seabed 9 at a "normal" quay level such that sea-going vessels 8 can berth for loading and unloading of cargo. Preferably such vessels include in particular sea-going cargo vessels transporting containers as cargo. On the platform 1 1 , equipment 10 is provided on the upper deck for enabling processing of cargo to or from one or more vessels (in figs. 16-18 one vessels is shown) moored to the quay structure. Such equipment may include mobile harbour cranes (MHCs) of up to 625 1 gross weight and/or for rail mounted ship-to-shore (STS) gantry cranes as shown in figs. 16-18, where the cranes may be adapted to load and unload containers on and off the cargo vessel moored to the quay structure. With reference to figs. 18 and 19, the barge 1 is anchored to the seabed 9 via a number of anchoring systems 3, which preferably include pillars 30 (see figs. 16, 17 and 19). This anchoring ensures that the lower section 1 ' is fully submerged in the water 7 but with the platform 1 1 of the barge at the predetermined level above the water line 71 so that a vessel can dock the quay structure. In a preferred embodiment, the top platform 1 1 is raised above the lower section 1 ' by the pillars 30 such that the upper deck is positioned at 4.90 m above medium sea level (MSL). The barge 1 is preferably dimensioned so that the top of the lower section 1 ' is positioned at 1 .30 m below MSL. This ensures clearance between the platform 1 1 and the lower section 1 ' allowing for tidal waves, such as mean high water spring of up to 1 .80 m above MSL. By this installation, the barge 1 is installed with a platform height so that it is suitable for berthing of sea-going vessels 8, as shown in the figures 16-18. By the invention it is realised that the barge 1 may be installed at other levels relative to the water line depending on local requirements or the like. The floating quay structure according to the invention may be an assembly of a series of barges 1 installed in line after each other extending from the shore 6. This quay structure may preferably be installed in the vicinity of the shore 6 and then be connected to the shore 6 by an access bridge 5 as shown in the figures 20-23. The access bridge 5 may be between a few meters and as long as 100 m depending on the location of the quay installation relative to the shore 6. The vicinity of the shore 6 may be characteristic by having a water depth of less than 100 m, preferably less than 50 m or even 25 m or less.

As shown in the figures 20-23, the access bridge 5 may be a floating bridge structure with an upper deck and a buoyancy box 5' fully submerged. The access bridge 5 is then secured to the seabed 9 by a number of pillars 5". At its upper deck the access bridge 5 is provided a road surface which allows for transport of cargo to and from the quay. Above, the invention is described with reference to some currently preferred embodiments. However, by the invention it is realised that other variants may be provided without departing from the scope of the invention which is defined in the accompanying claims.

Claims

1 . A floating semi-submersible structure for providing a quay for berthing sea-going vessels, said structure comprising

a barge comprising a platform with an upper surface and one or more buoyancy chambers for maintaining the upper surface of the barge above water level,

one or more anchors for securing the barge to the seabed,

wherein one or more of said anchors are arranged to hold said upper surface stable and level under varying loads on the upper surface via a permanent tension load due to the buoyancy of the barge.

2. A structure according to claim 1 , wherein the one or more buoyancy chambers are in a lower section which is fully submerged and with the platform mounted on top of said lower section.

3. A structure according to claim 1 or 2, wherein one or more of said anchors form an anchor system arranged to hold at least a part of the barge vertically and horizontally stable.

4. A structure according to any of the preceding claims, wherein the barge has a rectangular platform and lower section with four corners, and an anchoring system is arranged at least at the corners of said barge.

5. A structure according to claim 4, wherein the anchoring system is arranged at least in the corners of the lower section of the barge.

6. A structure according to any of the preceding claims, wherein one or more anchors and/or anchoring systems are arranged at least along the side edges of the barge, such as between the corners of the lower section.

7. A structure according to any of the preceding claims, wherein said one or more anchors comprises pillars which are coupled to the seabed, such as by driving it into the seabed, and under permanent tension due to the buoyancy of the barge.

8. A structure according to any of the preceding claims 2-7, wherein one or more, such as all, of said anchoring systems comprise pillars which are coupled to the seabed, such as via driven into the seabed, and under permanent tension due to the buoyancy of the barge.

9. A structure according to claim 7 or 8, wherein a pillar cap is provided on the top of the pillar and wherein the pillar is fixed to the barge via said pillar cap by fixation measures including any one of welding, threated engagement, locking pin engagement or the like.

10. A structure according to claim 9, wherein adjustment members are provided between side flanges on said pillar cap and an anchor plate in the barge.

1 1 . A structure according to any of the preceding claims, wherein one or more of said anchors or one or more of said anchoring systems, such as all of said anchoring systems, comprise

at least one tension leg with at least one mooring line secured to the seabed and pre-tensioned due to the buoyancy of the barge, and

at least one horizontal stabilising anchor connecting the barge to the seabed.

12. A structure according to claim 1 1 , wherein the at least one horizontal stabilising anchor comprises one or more pillars, such as spud piles, mounted to the seabed underneath the barge.

13. A structure according to claim 12, wherein the at least one horizontal stabilising anchor comprises one or more pillars according to one or more of the claims 8-1 1 .

14. A structure according to any of the claims 1 1 to 13, wherein one or more of the anchors are provided at each anchoring system, each comprising an inclined anchor chain between the barge and anchor point of the anchor in the seabed.

15. A structure according to any of the preceding claims, wherein the barge is provided with a ballast arrangement for controlling the buoyancy of the barge, such as a passive, dynamic or active pumping ballasting system.

16. A structure according to claim 15, wherein said ballast arrangement comprises a plurality of ballast tanks and ballast control system for supplying and discharging water to and from said ballast tanks.

17. A structure according to any of the preceding claims 1 1 -15, wherein the mooring line of at least one of said tension legs is a wire, cable and/or a chain.

18. A structure according to any of the preceding claims, wherein the barge is at least partially made of steel, such as more than 50% made from steel, such as more than 90% made from steel, such as more than 99% made from steel.

19. A structure according to any of the preceding claims, wherein the barge is at least partially made of concrete, such as more than 50% made from concrete, such as more than 90% made from concrete, such as more than 99% made from concrete.

20. A structure according to any of the preceding claims, wherein each of the anchoring systems of the barge are provided with an anchor mounting receiving compartment for receiving the tension leg mooring lines and a fixation compartment for receiving the horizontal stabilising anchors.

21 . A structure according to any of the preceding claims, wherein the barge is provided with equipment on an upper deck for enabling processing of cargo to or from one or more vessels moored to the structure, such as mobile harbour cranes (MHCs) of up to 625 t gross weight and/or for rail mounted ship-to-shore (STS) gantry cranes.

22. A quay arrangement comprising a plurality of sections of floating quay structures according to any of the preceding claims arranged abutting each other for forming a quay for berthing of sea-going vessels.

23. A quay arrangement according to claim 22, wherein one or more of the tension legs or anchors may be arranged to pull the sections towards each other.

24. A quay arrangement according to claim 22 or 23, wherein a connection member is provided between the barge and the shore, said connection member having an upper surface adapted to vehicle transportation of cargo to and from the quay.

25. A quay arrangement according to claim 24, wherein said connection member is a connection bridge having and floating structure and wherein said bridge is anchored to the seabed by one or more pillars and/or tension legs.

26. A method of installing a floating quay structure in a maritime environment, preferably on shallow water, said method comprising:

- providing at least one barge from off-site to a predetermined position,

- mounting at least one pillar at the predetermined positions by installing, such as by driving said at least one pillar, into the seabed underneath the at least one barge.

27. A method according to claim 26, further comprising

- submerging the at least one barge, such as by controlling the buoyancy thereof, so that the platform of the at least one barge is at a predetermined level above the water level;

- fixing the at least one barge to the at least one pillar; and

- lifting the at least one barge by establishing buoyancy and thereby tensioning the at least one pillar.

28. A method of installing a floating quay structure in a maritime environment, preferably on shallow water, said method comprising:

- preparing the seabed by mounting tension leg anchors for receiving mooring towlines at predetermined positions;

- providing at least one barge from off-site to a predetermined position, said barge having corners corresponding to the tension leg anchors;

- connecting the mooring towlines of the tension legs of the corners of the at least one barge to the corresponding tension leg anchors; and

- mounting at least one spud pile at the predetermined positions into the seabed underneath the at least one barge, such as by driving the at least one spud pile.

29. A method according to claim 28, further comprising the steps of

- submerging the at least one barge, such as by controlling the buoyancy thereof, such as by filling one or more ballast chambers; and after the step of connecting the mooring towlines, - lifting the at least one barge, e.g. by establishing buoyancy or reducing ballast, to position the barge at a predetermined level above the water level and thereby tensioning the tension leg towlines; 30. A method according to any of claims 26 to 29, whereby the at least one barge is provided with equipment on the platform, such as mobile harbour cranes or the like, pre-installed for enabling processing of cargo to or from one or more vessels moored to the structure.

31 . A method according to any of claims 29 or 30, whereby the mooring towlines are pre-installed on the tension leg anchors on the seabed before providing the barge on the mounting site.

32. A method according to any of claims 29 to 31 , whereby the mooring towlines are pre-installed on the barge.

33. A method according to any of claims 26 to 32, whereby the quay structure is mounted on shallow water in a coastal region.