Patent Description:
The present disclosure relates to floating caissons, and to methods and apparatuses of constructing floating caissons. The present disclosure further relates to structures including caissons.

Infrastructure in ports and harbours make marine traffic possible, and may facilitate facilitating loading and unloading of vessels. Furthermore they have to offer protection from tides and waves action.

In structures in port and harbour areas, caissons may be used. The use of floating caissons is relatively popular because it allows rapid construction in marine environments. Caissons may be used in the construction of e.g. breakwaters, ports, wharves, dry docks, fishing ports, berths, marinas and other.

Floating caissons are box-like elements, made of (reinforced) concrete, and which typically have a square or rectangular cross-section and have a number of empty cylindrical cells. Inner walls extending between opposite side walls form a grid and a number of empty cylindrical cells (with a square or rectangular cross-section) is formed in the grid.

Caissons provide stability and rigidity, and may for this reason be used in different port infrastructures as mentioned before. After construction, the caissons may towed with suitable towboats or other towing systems to their destination. Once in place, the caisson may be ballasted, i.e. the cells may be filled with concrete or granular material. This operation may be performed by auxiliary floating platforms that carry both the material and a special crane to transfer the material. Tractors, dozers, loaders and trucks may help finish the filling operation on top of the caisson.

A known technique for forming floating caissons is as follows: a slab of concrete may be formed and the parts of the inner walls are formed by pouring concrete in formworks. Once the concrete has formed, the formworks are lifted to form additional portions of walls on top of the already formed walls. Steel meshes may be used to reinforce the walls.

The walls may be formed in increments of e.g. <NUM> meter. Due to this technique, the shapes that can be used for the caissons are limited: in principle, only straight walls can be used. Also, this technique requires for the caisson building floating dock to be at least as high as the height of the structure to be built. This makes the caisson building docks very expensive, which means that only a very limited number of them may be use in a country. Infrastructural works may suffer important delays, because caisson building docks are unavailable.

<CIT> discloses an apparatus for constructing a floating caisson in accordance with the preamble of claim <NUM>. It discloses furthermore a method of forming a wall of a floating caisson layer-by-layer, as with and/or by a 3D printer.

The present disclosure in various examples provides methods, systems, and devices for manufacturing floating caissons and floating caissons that at least partially resolve some of the aforementioned disadvantages.

In a first aspect, a method of forming a wall of a floating caisson in accordance with claim <NUM> is provided.

In accordance with this aspect, a method of forming walls, portions of walls, and caissons are provided which allow more versatility in the shape of the caisson. Since no formwork is used, and concrete is sprayed on a support, the resulting wall may have any shape that can be given to the support. Also methods in accordance herewith require less complicated apparatus. Since the wall portion that has been formed is lowered, the surrounding apparatus does not need to be raised to construct subsequent wall portions.

The terms "spraying" or "shooting" concrete are used interchangeably throughout the present disclosure.

In some examples, the forming of one or more subsequent wall portions comprises providing one or more subsequent supports having first and second outer faces on top of the base supports and forming the subsequent wall portions by spraying or shooting concrete on the first and second outer faces of the subsequent supports. The terms subsequent supports and additional supports are used interchangeably throughout the present disclosure.

In some examples, lowering the platform may comprise reducing the buoyancy of the platform after the forming of each subsequent wall portion. The platform with already formed structure on top may be lowered by varying the buoyancy of the caisson and/or the platform. The caisson, to the extent that it has been constructed, may be filled with water as desired. The top of the formed structure may thus be lowered to be substantially level with the working decks, so that subsequent wall portions may be easily formed.

In some examples, reducing the buoyancy of the platform may include filling the platform with water. Particularly when the caisson has been constructed, the platform may be lowered and separated from the caisson to liberate the caisson from the apparatus used in making it. The caisson may then be towed and transported to its destination.

In some examples, the base supports and/or subsequent supports are made from a material that is relatively lightweight compared to concrete. Specifically, the base supports and/or subsequent supports may be made from polystyrene foam. Polystyrene foam is lightweight, is cheap and can be formed (by cutting, stacking etc.) in almost any desired shape.

In some examples, through-holes may be made or provided in the (base) support or additional supports. Connectors for connecting the wall portions on the first and second faces of the supports may be provided. The connectors may be prefabricated, or may be made in situ. In order to make connectors in situ, armatures may be placed in the through-holes and concrete may be shot or sprayed in the through holes.

In some examples, the end portions of the armatures may be folded to be substantially parallel the wall portions on the first and second faces.

In a further aspect, an apparatus for constructing a floating caisson in accordance with claim <NUM> is provided.

In accordance with this aspect, an apparatus is provided which may be more cost effective than prior art solutions. Particularly, the apparatus may be lower than known floating caisson building docks. In particular, the position of the platform with respect to the floating pontoon can be varied to allow for the manufacture of subsequent parts of the floating caissons. instead of constructing continuously at a higher level until the structure is finished, the construction may take place at substantially the same height. The already formed structure is lowered to be able to keep on working at substantially the same height.

The overhead structure may comprise a plurality of vertical supports supporting transverse beams. The working decks may be suspended from the transverse beams. Also the shotcrete distribution system may be guided along the transverse beams.

In some examples, one or more of the working decks may be movable with respect to a fixed part of the overhead structure, and particularly one or more of the working decks may be movable horizontally along transverse beams. The transverse beams may include guides or rails along which vertical supports connected to the working platforms may be displaced. Working decks that can be displaced can be helpful to allow for curved walls of caissons.

In yet a further aspect, a floating caisson comprising a bottom slab and a plurality of vertical walls in accordance with claim <NUM> is provided.

A caisson in accordance with this aspect may be relatively lightweight, i.e. for the same strength and stiffness, the caisson may be lighter than in the prior art. The core in particular may be lightweight. The core may be formed by the supports, as defined in the other aspects, upon which concrete is sprayed to form the walls. Concrete is provided on its outer faces. Particularly bending strength and stiffness of the resulting structure may be improved by providing the material further away from the neutral axis and avoiding a massive solid structure. The geometrical distribution of the mass of the structures has a higher second moment of area and thereby greater stiffness and strength for a given mass can be achieved. An aspect of the double-wall reinforced concrete surfaces is to remove the concrete which has the smallest or no load bearing effect, i.e. the effect is to remove the material that is not carrying much load and concentrating it where the load is highest".

In some examples, one or more of the vertical walls, and specifically external vertical walls of the floating caisson, may include a convex or concave shape. In some examples, one or more of the vertical walls may be doubly curved.

<FIG> schematically illustrate a method, and apparatus for constructing a floating caisson according to a first example. <FIG> provides a cross-sectional view, whereas <FIG> provide top views of the same apparatus of <FIG>, each of the figures highlighting a different subsystem.

<FIG> shows an apparatus <NUM> for constructing a floating caisson <NUM>. The apparatus may be floating in a body of water, e.g. in a part of a sea close to a shore, port or harbor where a structure is to be built.

The apparatus <NUM> comprises a floating pontoon <NUM>, and a submersible platform <NUM>, which is connected to the floating pontoon <NUM>. The connection is such that a vertical position (inside the water) of the platform <NUM> can be varied with respect to the floating pontoon <NUM>. In this particular example, the connection between the floating pontoon <NUM> and the platform <NUM> may include one or more cables or chains or mooring lines, which may be connected at anchoring points <NUM> and <NUM>. The connection may include pulleys or winches as needed.

The apparatus <NUM> further comprises an overhead structure <NUM> supported by the floating pontoon <NUM>, wherein the overhead structure <NUM> comprises one or more working decks 40A, 40B and a shotcrete distribution system <NUM> for supplying shotcrete to workers on the working decks. The working decks are configured to support workers on the working decks. They may allow workers to move around on them.

Shotcrete, (sometimes called "gunite" or "sprayed concrete") is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique. The wall formed in this manner may be reinforced by conventional steel rods, steel mesh, or fibers. Shotcrete as used throughout the present disclosure may refer to both wet-mix and dry-mix versions.

In some examples, the submersible platform may have variable buoyancy to vary a position of the submersible platform <NUM> with respect to the pontoon and / or with respect the floating caisson <NUM>. The platform <NUM> may have a system to control ingress and egress of water. Suitable (bilge) pumps and valve systems may be used.

In the top views of <FIG>, it may be seen that the floating pontoon <NUM> may have an open cross-section, and may be substantially U-shaped or C-shaped. With reference to <FIG>, it may be seen that several rows of inner working decks 40A may be arranged between the legs of the U-shape. In this particular example, four rows of inner working decks may be arranged. Each of the rows includes three inner working decks 40A. Additionally, an annular outer working deck 40B may be provided. The annular working deck may substantially surround all the inner working decks 40A.

With reference to <FIG> and <FIG>, it may be seen that the overhead structure <NUM> may include a plurality of vertical side supports <NUM> and a plurality of transverse beams <NUM>. Each of the transverse beams <NUM> may extend between vertical side supports <NUM>. The vertical side supports <NUM> may be directly positioned on top of floating pontoon <NUM> and carry the transverse beams <NUM>.

As illustrated in <FIG>, the overhead structure may be formed or may comprise truss structures. The vertical supports <NUM> may extend between working decks 40A and 40B and a transverse beam <NUM>. The vertical supports <NUM> may be suspended from the transverse beams <NUM>.

In some examples, each of the inner working decks 40A may comprise an intermediate vertical support <NUM>. In some examples, one transverse beam <NUM> may be arranged with each row of working decks <NUM> A.

With reference to <FIG>, it may be seen how a shotcrete distribution system <NUM> may include a central supply <NUM>. From the central supply <NUM>, several transverse distribution lines <NUM> may extend sideways. Each of the transverse distribution lines <NUM> may include one or more delivery hoses <NUM> (illustrated in <FIG>). The distribution lines may be supported by transverse beams <NUM>. If the transverse beams <NUM> are formed as truss structures, the distribution lines may advantageously be arranged inside the truss structures.

The hoses <NUM> may be held by workers on the working decks 40A, 40B and may be used for spraying or "shooting" concrete. In some examples, the hoses may be arranged with the vertical supports <NUM>. In some examples, a hose may be arranged with each of the vertical supports <NUM>.

Shotcrete machines are available which can control the concrete spraying process and make it very fast and easy. Manual and mechanical methods may be used for the wet spraying process but wet sprayed concrete is traditionally applied by machine.

An apparatus according to the present disclosure may be relatively easily transported. it may be dismounted and transported by road (truck) or by sea to a construction site. The vertical supports <NUM>, side supports <NUM> and transverse beams may be relatively easily disassembled from each other.

It may also be appreciated that the build-up of the apparatus illustrated herein is modular and may be easily scaled up as needed.

Using an apparatus such as the one shown in <FIG>, a method of forming a wall <NUM> of a floating caisson <NUM> may comprise providing a slab <NUM> on a submersible platform <NUM>. One or more supports <NUM> may be provided on top on top of the slab <NUM>, the supports <NUM> having a first outer surface <NUM> and a second outer face <NUM>. A wall portion may be formed by spraying or shooting concrete on the first and second outer faces <NUM>, <NUM> of the supports <NUM>.

Then, the platform <NUM> may be lowered. Subsequent wall portions may then be formed on top as needed.

The walls may thus be formed by spraying or shooting concrete on the supports. The supports <NUM> may be chosen to be lightweight. This shall be understood in the present disclosure as a support with a density that is lower than the density of the concrete sprayed on its face.

The supports <NUM> in examples may extend substantially perpendicular to the slab <NUM>.

One example of a support is polystyrene foam. Polystyrene foam is lightweight, and may be cut, sized and shaped and arranged in a wide variety of ways. Thus any suitable support shape may be provided upon which concrete can be sprayed. The thickness of the concrete on either face of the support may be varied as needed. As a result, a wide variety of shapes and forms may be provided for the walls of the caisson. a wall of the caisson may be curved, e.g. be concave or convex. A wall of the caisson may have a double curvature, i.e. may be curved both in a vertical and a horizontal direction. Even though any of the walls of the caisson may be curved in this manner. The curvature of the outer walls of the caisson may be particularly suitable, e.g. when they have to function as breakwater structure. The curvature of the outer walls of the caisson may be chosen such as to absorb impact of incoming waves and/or to divert incoming waves suitably.

Other materials may also be used for the support, e.g. wood or polymer structures. The supports may be partially hollow in some examples.

A process of constructing a wall or a plurality of walls of a floating caisson starts with the arrangement of base supports on slab <NUM> to form the bottom section of the walls. Once the bottom portion of the wall(s) has been formed, the platform <NUM> is lowered. Then, subsequent wall portions are formed until the desired height for the walls is reached. The forming of one or more subsequent wall portions comprises providing one or more subsequent supports having first and second outer faces on top of the base supports and forming the subsequent wall portions by spraying or shooting concrete on the first and second outer faces of the subsequent supports.

Wall <NUM> may be formed by a worker from the annular outer working deck 40B for one face of the wall and from an inner working deck 40A for the other face of the wall. The situation is similar for wall <NUM>. For wall <NUM>, spraying may be performed from two neighboring inner working decks 40A. The same applies to wall <NUM>. It is noted that only a cross-section is shown in <FIG>. The floating caisson may have a plurality of walls that extend perpendicular to the walls <NUM>, <NUM>, <NUM> and <NUM>.

In some examples, armatures may be positioned along the faces of the supports <NUM> prior to shooting concrete. The armatures may be steel meshes, or fiber reinforced composites (e.g. glass fibers, carbon fibers or Kevlar® fibers).

In some examples, the supports <NUM> may have through-holes extending from the first face <NUM> to the second face <NUM>. In other examples, the through-holes may be made in situ (e.g. they may be driller or bored, or carved out or otherwise). In order to reinforce the resulting wall structure, connectors may be provided through such through holes.

The connectors may be prefabricated or may be made in situ. As the wall portions, concrete may be used for the connectors. In a particular example, a reinforcement, such as a steel mesh or steel bars may be positioned in the through-hole substantially extending from the first face <NUM> to the second face <NUM>. When concrete is shot on the faces <NUM>, <NUM>, the spaces of the connectors may be filled with concrete at the same time.

In some examples, the steel meshes or steel bars of the connectors may be folded at both ends to be substantially parallel to the walls.

An aspect of examples of the methods disclosed herein is that the overhead structure including working decks may stay substantially at the same height throughout the entire construction process of a caisson. The floating caisson, to the extent that it has been constructed, is lowered. Subsequent wall portions may thus be formed from the same height. The operators (and working decks) thus stay in substantially the same position. In prior art solutions, the caisson building floating docks, need to be at least as high as the heights of the structure to be built, since formworks are used.

In some examples, the buoyancy of the platform may be reduced after the forming of each subsequent wall portion. In some examples, the platform may be filled with water as needed to vary its buoyancy. Once wall portions of the caissons have dried up, the caisson may be filled with water to a desired level WLin. This water level does not need to be the same as the overall water level WL at sea, and in general will be different.

<FIG> schematically illustrate different stages in a method for constructing a floating caisson according to an example. In <FIG>, the first step of spraying concrete is about to take place. It may be seen in <FIG> that a slab has been arranged on platform <NUM>. Such a slab may be made as known in the art. The slab may be made of (steel) reinforced concrete. Steel bars may stick out upwards from the slab. Also the slab may contain stub(s) forming the beginning of the walls to be created. Then base supports <NUM> are may positioned. Reinforcement (steel) meshes may be arranged on either side of the supports <NUM>.

Then, concrete is sprayed on the base supports <NUM>. In some examples, the base supports <NUM> may be entirely covered in such a step. In other examples, the base supports <NUM> that are positioned may not be entirely covered. the base supports <NUM> may have a height of <NUM>,<NUM> or <NUM> meters, whereas in a single step <NUM> meter of concrete is sprayed and then left to dry. It should be clear that these dimensions are only examples, and that in practice they may be varied.

After the concrete has dried, the platform <NUM> with the caisson is lowered. As mentioned before, the caisson may be filled with water as need to lower the caisson structure to the level needed. Then, a next portion of wall may be made by repeating the same process. Additional supports may be positioned, reinforcements may be arranged along the first and second faces, and concrete may be shot. In some or all of these steps, connectors between the faces may be provided as explained in other parts of the present disclosure.

In the situation of <FIG>, the total height of the walls has been constructed. As such, the floating caisson <NUM> is finished. It may be seen in <FIG>, how the top of the walls is substantially level with the working decks. In order to remove the caisson <NUM> from the apparatus, the caisson may be flooded with water to a desired level WLIN. The submersible platform <NUM> may also be flooded with water as needed to separate it from the floating caisson, see <FIG>. The caisson may then be pulled out and transported to the site of construction.

In accordance with examples disclosed herein, a floating caisson is constructed that comprises a bottom slab and a plurality of vertical walls. The vertical walls comprise a core of a first material, and a first shotcrete layer on a first face of the core and a second shotcrete layer on a second opposite face of the core. The resulting floating caisson may be lighter than similar caissons in the prior art. The strength and stiffness however may still be the same as in the prior art. Less concrete is needed to reach the same level of bending strength.

The core may be made from a lightweight material, optionally polystyrene foam. The first and second concrete layers may be made of reinforced concrete. The bottom slab may be made from concrete as well, optionally reinforced concrete. In some examples, one or more of the vertical walls, particularly the outer walls of the caisson may include a convex or concave shape. The core may be formed by the base support and additional supports mentioned before.

<FIG> schematically illustrate an example of a caisson that may be used in structures along the shore. <FIG> shows a side view of a caisson <NUM> that may be used in a structure such as a pier, seawall or jetty. Jetties may be used e.g. to delimit harbors. Sea side is indicated with reference sign <NUM>, and lee side is indicated with reference sign <NUM>. The sea side wall <NUM> may be substantially concave and may function as breakwater. The lee side wall <NUM> may also be curved, but have a different curvature than the sea side wall. Reference sign <NUM> indicates a top surface of the caisson <NUM>. The top surface <NUM> of caisson <NUM> may be used by pedestrians and other traffic once the caisson has been constructed and is operational.

With examples of the methods disclosed herein, the upper portion <NUM> on the sea side wall <NUM> forming a barrier or wall may be formed integrally with the caisson and the sea side wall. In prior art solutions, such a wall would normally be added in situ after placement of the caisson.

<FIG> illustrates how a caisson <NUM> may have been transported to the construction site to be placed. The caisson <NUM> may be ballasted and positioned on bedding <NUM>.

<FIG> schematically illustrate a further example of an apparatus for constructing a floating caisson. In the example of <FIG>, the apparatus <NUM> comprises a floating pontoon <NUM>. Like the previous example, a superstructure of the apparatus <NUM> comprises vertical side supports <NUM> and transverse beams <NUM>. The working decks 40C and 40D are coupled to vertical beams <NUM> suspended from the transverse beams <NUM>. Similarly to the previous example, a shotcrete distribution system <NUM> for supplying shotcrete to workers <NUM> on the working decks.

Further, as in the previous example, a submersible platform <NUM> may be connected to the floating pontoon to vary the vertical position of the submersible platform. The position of the submersible platform may be changed without changing the vertical position of the floating pontoon. A connection between the pontoon <NUM> and platform <NUM> may include a plurality of chains, wire ropes, cables or similar. Anchoring points <NUM> and <NUM> may be provided as commented before.

The floating caisson <NUM> to be constructed in this example is slightly different from the example of <FIG>. A middle wall of floating caisson <NUM> is a substantially vertical straight wall, whereas the front and rear walls are curved. <FIG> illustrates how the supports <NUM>, <NUM> upon which the shotcrete is shot may be different for the different walls.

One difference between the example of <FIG> and the example of <FIG>, is that vertical guides <NUM> extend between the sea bed SB and the submersible platform <NUM>. The guides <NUM> facilitate the platform <NUM> to move vertically and not drift.

A further difference between the example of <FIG> and the example of <FIG> is that one or more of the working decks may be movable, and in particular one or more the vertical supports <NUM> carrying working decks 40C may be displaced along transverse beams <NUM>. The transverse beam may comprise rails or guides, along which the vertical supports <NUM> may be slid. Also the outer working deck 40D may be displaced in a similar manner.

The floating pontoon <NUM> may have a closed perimeter as may be seen in the top view of <FIG>. In a horizontal cross-section, the floating pontoon <NUM> may have a square ring-shaped form, or gates are provided to close the C-shape or U-shape of the pontoon.

The platform <NUM> may have a system to control ingress and egress of water. Suitable (bilge) pumps and valve systems may be used. Water lines <NUM> may be used to selectively fill the platform <NUM>. One or more water lines <NUM> in some examples may lead from pontoon <NUM> to submersible platform <NUM>.

<FIG> schematically illustrates a further example a construction method of a caisson. <FIG> illustrates a first step (or one of the first steps) for constructing wall portions with base supports <NUM>, <NUM>. At the stage of <FIG>, a slab of concrete has been provided, with relatively small stubs where the walls are to be formed.

The outer walls of the floating caisson in this example are curved. The working decks 40C and 40D may be horizontally moveable to allow workers to shoot concrete on the supports, even as the walls are curved. Between the steps of <FIG> and <FIG>, the working decks are horizontally moved. The last construction step may be seen in <FIG>. A curved support <NUM> is placed to form the last portion of a sea side wall of the floating caisson.

When the floating caisson has been finished, <FIG>, the submersible platform <NUM> may be filled with water to sink the platform <NUM>. The floating caisson may then be towed away.

<FIG> schematically illustrates a method for transporting a floating caisson once constructed. It was noted before that the pontoon <NUM> of the apparatus <NUM> may form a closed cross-section. In order to tow a floating caisson <NUM> to a construction site where it may be filled to sink it, a towing vessel <NUM> using cables <NUM> or similar may tow the floating caisson <NUM> away. One side <NUM> of the floating pontoon may be closed off with gates 13A and 13B which may be opened after construction is finished.

<FIG> and <FIG> illustrate examples of working decks 40C and 40D. The working decks 40C may include a female receiving portion to mate with a bottom portion of the vertical supports <NUM>, such that the vertical support <NUM> can fit inside and the working deck may thereby be attached to the vertical support. The working surface <NUM> of the working deck may be substantially flat so that workers may move around comfortably and safely. Several ribs <NUM> may be seen that reinforce the working decks 40C, 40D.

While the use of shotcrete has generally been described in the illustrated examples, and walls of floating caissons are formed generally by shooting or projecting concrete on a support, in other examples, classic formworks may be used. Substantially the same apparatus including pontoon, submersible platform and a similar overhead structure including working decks may be used in these cases. Instead of shotcrete, concrete for formworks may be supplied through a suitable distribution system.

Claim 1:
A method of forming a wall (<NUM>, <NUM>, <NUM>, <NUM>) of a floating caisson (<NUM>, <NUM>, <NUM>) comprising:
providing a slab (<NUM>) on a submersible platform (<NUM>);
providing one or more base supports (<NUM>, <NUM>) on top of the slab (<NUM>), the base supports (<NUM>, <NUM>) having a first outer face (<NUM>) and a second outer face (<NUM>);
forming a first wall portion by spraying concrete on the first (<NUM>) and the second (<NUM>) outer faces;
lowering the platform (<NUM>) below a water level; and
forming one or more subsequent wall portions on the first wall portion.