A floating pontoon body to be tied together with at least another pontoon body.

The present invention relates to a floating pontoon element, configured to be tied together with at leas one second floating pontoon element, thereby forming a post- tensioned interconnected floating body. The pontoon element comprises a deck plate of concrete and downwards protruding vertical walls of concrete, thereby forming a hollow floatable body. Along their side wall edges, said pontoon elements are configured with an upper and lower pulling tube intended to contain cables or the like, in order to tie the two or more pontoon elements together both along the upper and the lower edges of the pontoon elements .

The invention is in particular suited for establishing elongate floating bodies, for example intended for use as breakwaters or floating piers for small boat harbours .

It has previously been proposed to build floating piers, for example for small boats, by means of a plurality of separate pontoon elements which are tied together, forming a large elongate floating body. It is common practice to connect said various floating elements together by means of pivotal link, allowing relative movement between two adjacent, neighbouring floating bodies. Alternatively, several floating bodies may be tied together, for example by means of tensioned cables, thereby forming one post-tensioned, interconnected unit.

For floating breakwaters it is a requirement of a rigid body having capacity of stopping the waves, and to a largest extent, to reduce the wave energy. For such type of structures the floating body must be as strong and rigid as possible.

US 3,977,344 describes a floating concrete structure formed of at least two modules which are tied together by means of post-tensioned cables, arranged along the upper

and lower side edges of the modules. The floating concrete structure consists of an elongate main body, formed of module units tied together, and slipway units tied into the elongate main body in a perpendicular configuration. The slipway units are also tied to the main body by mean of post-tensioned cables extending along the upper and lower side edges of the slipway unit.

US 20056/0103250 describes a floating unit made up of a plurality of buoyant bodies tied together by means of post-tensioned cables, arranged along the upper and lower side edges of the buoyant body.

When constructing and assembling floating piers, floating breakwaters and the like, the dimensions are often based on existing requirements and demands, and/or adjusted to limited economical funding. At a later stage, there is often a need of increasing the capacity and/or the size and dimensions of the existing, already installed floating pier, breakwater or the like.

For piers or the like formed of separate units, linked together by means of hinges, it is simple to extend or increase the capacity of the floating pier. In such cases it is only necessary to attach one or more new elements to the existing unit, which causes no problems at all. If at a later stage, however, it is necessary to increase the capacity and/or size of an already assembled floating pier, breakwaters or the like, formed of elements tied together by post-tensioned cables, large inherent limitations exist. In such cases where it is required or necessary to increase the capacity, etc., the results are often that the existing floating pier or the floating mole is substituted or replaced by a completely new breakwater or pier, tailor made for the new, intended size and/or capacity.

A further problem to be catered for is the dimensions and size of each element to be incorporated into the floating body. Due to economical aspects of road transport

of pontoon units from the production plant to the intended place of use, each pontoon unit should not have a length exceeding 15-20 m and should further not have a width exceeding to any degree the width of a trailer or a lorry.

An object of the invention is to provide a system which, by means of a simple method and means, in an economical manner and based on an existing floating unit, may be adjusted to increased requirements for capacity and/or size of the floating pier, breakwaters or the like, without having to substitute the existing system with a completely new pier or the like.

Another object of the invention is to provide a flexible system for assembling floating bodies where capacity increase of existing floating piers, breakwaters or the like, may be performed in a simple and economical manner, while said floating bodies are on site, floating at the sea level.

A further object of the inventions to provide an assembly where the risk for cracking of the pulling ducts due to frost, or corrosion of the post-tensioned cables due to intrusion of sea water subsequent to the post- tensioning operation, is substantially reduced.

A still further object of the invention is to provide an assembly where it is possible, on a more or less permanent basis in a physical manner, to prevent intrusion of sea water into the pulling ducts, thereby avoiding cracking caused by freezing sea water.

A still further object of the invention is to provide a solution where the dimensions of the mooring chains or system may be optimized without reducing the integrity and safety of the floating body.

The objects of the present invention are obtained by a floating pontoon body as defined in more detail in the characterizing part of the independent claim, read in context with the preamble of such claim.

Further embodiments of the invention are defined by

the dependent claims.

According to the invention, at least the pulling ducts extending along the lower side edges of floating element (s) are configured in such way that it is possible to lengthening the floating body made up of two or more interconnected pontoon elements with additional pontoon elements, such lengthening being performed while the floating pontoon body is in its floating state.

According to a preferred embodiment of the invention, said pulling ducts are terminated at a level above the sea level, at least at one end. Such arrangement enables the tie-up operation to be performed above the sea level, such that expensive underwater works related to tie-up and tensioning of several floating elements with associated work of divers, may be eliminated.

From the lower side edge of the pontoon element, the lower pulling ducts may extend slanted upwards.

The pulling ducts may optionally have a slight curvature or may be more or less straight from their lower level towards the sea level, and the lower pulling ducts are preferably terminated in the deck plate, the upper end of the pulling duct preferably being terminated at a distance away from the end wall of the pontoon element.

Further, pulling duct may extend from said termination in the deck slab and outwards towards the free end surface of the pontoon element, said termination of pairs of pulling ducts in the deck slab being arranged in a recess or well in the deck slab, where the surfaces of the well in which the ducts terminates, are substantially vertical and having a width and height allowing support for a tensioning jack used to tension the post-tensioned cables .

The well may be arranged on each side of the deck slab, substantially exactly above the side wall wherein the pulling ducts are arranged.

Since the pontoon elements are tied together forming

a more or less integrated body, each single pontoon element will to a very small degree, if at all, move relative to the adjacent, neighbouring pontoon element. Hence, one tied up integrated body is thus established. As a consequence, each chain forming the mooring system of the floating body will more or less take an even share of the forces induced, i.e. the forces will be evenly distributed through the various mooring chains. Since cushions or damping plates are arranged on adjacent surfaces being in contact with each other, this effect is in particular enhanced by the transition zone between each pontoon element, at or in relation to the duct/ducts containing the tensioned cables. Such cushions or damping plates will prvide a certain damping effect, while at the same time they will prevent crushing of the concrete material in the adjacent wall sections, and compensate for small relative movements. In addition, the damping plates will ensure that the point loads are taken by the four corners of the end surfaces.

A still substantial advantage according to the present invention is the possibility of distributing the appearing forces on cross sections designed to withstand such forces.

Preferred embodiments of the invention shall be described in detail below, referring to the accompanying drawings, where:

Figure 1 shows a side view of a preferred embodiment of the invention, where the floating body is formed of three inter-tied pontoon elements;

Figure 2 shows a view seen from above of a start section or a middle section of the floating body shown in Figure 1;

Figure 3 shows a view seen from above of an end section according to the invention;

Figure 4a shows a vertical section through a start section or a middle section, see along the line A-A in

Figure 2;

Figure 4b shows a vertical section through the end section according to the invention, seen along the line B- B on Figure 3;

Figure 5a shows an end view of a free end the start section shown in Figures 1 and 2;

Figure 5b shows an end view of one middle section and one end section, alternatively one end of a start section, all intended to be linked together with the corresponding end of an adjacent pontoon element;

Figure 6 shows schematically a view seen from above of an alternative embodiment of a breakwater constructed according to the principles of the invention;

Figure 7 shows a section in part of two end surfaces of two adjacent floating elements, where one of the floating elements is provided with a protruding dowel, while the opposite floating element is provided with a corresponding recess; and

Figure 8 shows a view of an end surface of the floating pontoon element.

Figure 1 shows a view of a preferred embodiment of a floating body 10 according to the present invention. As shown in the Figure 1 three separate units are used. One unit forms a first start section 11, the second unit forms a middle section 12 and a third unit forms the end section 13, the latter being different compared with the start section 11 in that it is inverted. In addition, compared with the start section 11, the end section 13 differs in that the ends for the tensioning cables are terminated in a well 19 in the deck slab 15 above sea level, and that the end section further is configured for tie-in and attachment of a new section.

Each unit 11,12,13 comprises an upper deck slab 15, pairs of side walls 16 extending longitudinally of the unit, and two opposite end walls 16' , extending downwards from the deck slab 15 at the end of each section 11,12,13.

Each unit 11,12,13 is downwards open, i.e. they are not provided with a lower bottom. The units 11,12,13 are further filled with a plurality of polystyrene blocks 17, arranged side by side, filling out at least parts of the volume contained inside the vertical walls 16,16' and deck slab 15.

As shown in Figure 1, the upper and lower pulling ducts of the end section 13 are configured in such way that they are terminated in a well or a recess 19 in the deck slab 15. Upper and lower pulling ducts extend in longitudinal direction towards the free end wall 16' . For the embodiment shown in Figure 1 and 2, no tensioning cables are shown installed in the ducts, since said ducts are to be employed later if a new floating element consisting of one or more similar sections 11,12,13 is to be added and tied in on the already established floating body 10.

If its should prove necessary at a later stage to extend the floating body, i.e. subsequent to the floating body 10 shown in Figure 1 being installed and moored to the operation site, a new floating section, e.g. formed of a inter-tied unit consisting of two end sections 13 and an intermediate middle section 12, or a start section 11, an middle section 12 and an end section 13, is floated to the referenced site and manoeuvred into position with respect to the installed and moored section end 13 of the floating body 10. Upper and lower cables are then pulled in from the arriving unit to be tied in to the existing unit through the yet unused pulling ducts in the moored end section 13 to the well 19. The cables are then tensioned, forming a new, extended elongate floating body 10.

The free end of the new floating body may correspondingly be provided with a well 19 and unused pulling ducts installed at the free end of the moored new end section, still leaving the option at a later stage of 19 extending the floating body 10 even further, if considered

necessary.

Figure 2 shows a view of the floating body 10 shown in Figure 1, seen from above. As shown in Figure 1 the three units 11,12,13 are tied together by means of tensioned cables 14,14'. The tensioned cables 14,14' run freely inside the pulling ducts. The pulling ducts and the tensioned cables 14,14' will be described in further details below. The space below the deck slab 15, between the deck slab 15 and the downwards protruding sidewalls 16,16' are filled with blocks 17 of polystyrene, adding buoyancy and stability to the floating body 10.

Further, the floating body 10 is provided with ducts of channels 21 for the ends of moorings (not shown) or the like, for example comprising chains extending between the floating body 10 and anchors on the sea bed, thereby providing a safe mooring of the body 10.

Figure 3 shows a view seen from above of an end section 13 according to the invention. As shown in the Figure the end section 13 is provided with two wells 19, arranged on opposite sides of the end section 13 above the side walls 16. The pulling ducts with cables 14,14' from the other sections 11,12 are terminated in the wells 19. Further, pairs of redundant pulling ducts extend from the wells 19 on each side in the middle part of the section 13 towards the free end 16' of the referenced section 13.

Figure 4a shows a vertical section through a middle section 12 according to the invention, seen along the line A-A in Figure 2, while Figure 4b shows a vertical section through an end section, seen along the line B-B in Figure 3. As shown in the Figures a pontoon body 10 comprises generally a deck slab 15 of concrete and downwards projecting concrete walls 16 extending along both sides of the pontoon body 10 and further comprises downwards projecting end walls 16' . Beads 20 or voutes are provided in the transition zone between the deck slab 15 and the side walls, including at the lower edges of the lower,

free ends of the side walls. The pulling ducts 14, through which the post-tensioning cables are intended to be drawn, are embedded in said beads 20. As indicted in Figure 4a the lower beads 20 or voutes on the middle section 12 and along those parts of the start section 11 and end section 13 being horizontal, will be placed along the lower, free end of the side walls 16. Figure 4b indicates that the beads 20 correspond to the curved curvature of the pulling ducts 16 of the end section 13 and at the one end of the start section 11.

Figure 5a and 5b shows a view of two different, typical ends according to the invention. Figure 5a shows the free end of the start section 11. As shown in the Figures, the pulling ducts and the post-tensioning cables are terminated above the sea level, for example in connection with a plate (not shown) for distribution of the forces imposed by the post-tensioned cables 14,14' inside the concrete, said plate also functioning as a support surface for the end anchors of the post-tensioned cables IA ₁ IA' . It should be appreciated that the start section 11, which optionally is intended to be moored to one or more mooring points ashore, may be provided with suitable mooring points (not shown) for such purpose. In addition or in lieu of said mooring points, the start section 11 may optionally be provided with mooring points 21 corresponding to the ones shown in connection with the opposite end of the pontoon element 13.

Figure 5b shows another typical end surface 14'. The Figure shows the shape of the end surfaces 14' of the middle element 12 and the end surfaces 14' of the end element 13. In addition, the end surface 14' of the start element 11, intended to be tied up against the end surface 14' of the middle element 12 correspondingly shaped.

The elements 12,13 intended to be tied up with an existing floating body 10 must have an end surface 14' which corresponds to the end surface shown in Figure 5b.

This implies that the adjoining elements must have a design which corresponds to the end surface of the middle element 12 and/or the end element 13.

A substantial advantage of the solution according to the invention comprises establishing of tight connections at the transition from the termination end of a pulling duct at one end wall and the corresponding termination end of the adjoining pulling duct in the adjacent end wall. A possible solution is to arrange a plate 18 of a material having, to a certain degree, deformable and tightening properties, the plate being fixed to one of the end walls of an element 11,12,13. This implies that when two elements 11,12,13 are tied together, then preferably only a single plate 18 rests against the concrete surface on the adjoining element 11,12,13. Due to the tensioned cables, the elements are pressed towards each other, forming a tight connection or joint between two end walls 16' .

In the Figure, use of rectangular or square plates is indicated. It should be appreciated, however, that circular plate having a centrally arranged opening preferably may be used, the plate preferably being arranged in a conically shaped recess having a larger outer diameter and a smaller inner diameter. Such shape caters for possible accumulation of material in the outer part of the plate, caused by the compression of the plate during tensioning of the cables. The diameter of the cylindrically shaped plate may preferably correspond to the inner diameter of the recess.

Figure 6 discloses a preferred embodiment where the various pontoon elements 11,12,13 are connected together in order to form a breakwater. As indicated in the Figure, each pontoon element is straight, but may have more or less skewed end surfaces, thereby forming more or less curved floating body when two or more elements are tied together. The end walls 16' may preferably be skewed at an

angle in the order of 10° to 30°. The pontoon elements are tied together in a similar way as described above, i.e. both along their upper and lower edges and along both longitudinal sides of the pontoon elements 11,12,13. An interconnected, tied-in breakwater according to the invention is moored in such way that the convex side of the breakwater faces towards the direction from which the waves are coming, ref. the arrows indicated in Figure 6. The one or both ends may be formed with a pontoon element 13, corresponding to pontoon element 13 described above. According to the embodiment shown in Figure 6, one end of the breakwaters may be moored to shore or the like, while the opposite end of the floating body may be moored to the sea bed by means of a mooring (not shown) . Hence, the breakwaters shown is formed of a start element 11, a number of intermediate elements 12 and an end element 13, configured for possible later extensions, such as described above. It should be appreciated, however, that other configurations also are possible, without deviating from the inventive concept .

Figure 7 and 8 show a preferred embodiment of two adjacent ends of a floating body 10, where one end is provided with at least one dowel 22 projecting outwards from the end surface and intended to be inserted into a corresponding recess 23 in the adjacent end surface on an adjacent element, so that the bodies 10 are centred with respect to each other in the tie-up phase. In order to secure a proper centring effect two dowels may preferably be used, arranged a distance apart.

Generally, it should be appreciated that the method for connecting the elements described above is intended to be used for connecting together two or more pontoon elements, forming for example piers or moles having a length of for example 300-400 m or more.

According to the embodiment shown in the Figures two pulling ducts are shown along the upper edges of each

element and two pulling ducts are used along the lower edge. It should be appreciated, however, that a person skilled in the art may, based on the appearing loads, forces and functions which the pontoon element is intended to cater for, use a different number and other configurations of the pulling ducts. This implies that the number of pulling ducts along the upper edge may differ from the number used along the lower edge. The same is applicable for the number of tensioned cables employed.

According to the solution forming the present invention, it is possible to tie together a large number of elements and/or add a large number of elements to existing structures, in order to form an elongated structure, if deemed required. It is possible, for example, to use a start element 11, i.e. an element being intended to be placed close to and moored to shore. Further, a middle section 12 and an end section 13, tied up with the middle section 12 at one end, may be used, preserving the possibilities of adding further floating pontoon sections at a later stage.

The tensioning cables used for tying together the various floating elements 11,12,13 may be made of steel or of strings or strands of a composite material, where the load absorbing part may be made of carbon fibres or of basalt fibres.