Patent Description:
In recent years, the technology for realizing offshore airports and floating cities/marine cities (referred to as "floating cities" hereinafter) is being developed globally.

For example, in order to realize a very large floating structure (VLFS) extending over several thousands of meters, demonstration experiments of so-called Mega-Floats have been performed on the actual sea from the year <NUM> to the year <NUM>. A Mega-Float is a very large floating platform constructed by connecting a plurality of box type floating structures by welding.

According to these demonstration experiments, it has been pointed out that a very large floating platform has a structural flaw, such as stress concentration, in rough waves. In order to compensate for such a flaw, there has been proposed an idea for completing a single very large floating platform by connecting the plurality of barge type floating structures or semi-submersible floating structures by using movable joints (i.e., hinges). With this idea, it has been confirmed from water tank experiments that safety is ensured even in rough waves.

However, even though this floating platform solves the structural problem of, for example, stress concentration, the floating platform is not suitable for use in an offshore airport or a floating city since the entire floating platform deforms due to the movable joints. Moreover, in either case, since uniform buoyancy has to act on the entire floating platform, if the load on the floating platform changes significantly, as in a floating city, it is difficult to cope with such changes in the load.

On the other hand, several large floating platforms that utilize pneumatic stabilized platforms in place of barge type floating structures have been proposed. The structure of a pneumatic stabilized platform may be one of various types, including a type (air chamber type) provided with a plurality of air chambers by dividing a floating structure with a partition wall and a type (continuous open bottom type) in which a plurality of floating module units each having an open bottom are connected by using hinges or bolts.

Known examples of the former type include a floating structure divided into eight segments by using partitions for the purpose of serving as a pneumatic circular floating buoy (Patent Literature <NUM>: <CIT>), a floating-city floating structure that is hermetically provided with a peripheral frame having an open bottom around the lower surface of a flat disk and that is provided with a plurality of compressed air chambers in an internal space surrounded by the lower surface of the flat disk and the inner surface of the peripheral frame so as to maintain equilibrium with a total load applied to the flat disk when set on the water surface (Patent Literature <NUM>: <CIT>), and a pneumatic floating structure provided with a plurality of cells separated from one another by concrete hexagonal partition walls (Patent Literature <NUM>: <CIT>).

However, the floating structures described in Patent Literatures <NUM> to <NUM> share a common feature in which the flow of air between air chambers separated by partition walls is blocked, and are thus not suitable for use as the structure of a very large floating platform.

A structure suitable for a very large floating platform can be achieved by connecting a plurality of air chambers and causing air to flow therebetween to attenuate a wave force. Known examples of such a structure that achieves a very large floating platform include a type in which a wave force is attenuated by connecting a plurality of cylindrical floating structures by welding and causing air to flow through gaps between the cylindrical floating structures (Patent Literature <NUM>: <CIT>), and a type in which multiple steel cylinders are coupled together (Patent Literature <NUM>: <CIT> Pamphlet).

Known examples of the latter type include a concrete rectangular-element-coupled floating structure that uses an air pump to compensate for decreasing air (Patent Literature <NUM>: <CIT>), an artificial floating island formed of a plurality of floating module units (Patent Literature <NUM>: <CIT>), and a floating structure in which a plurality of containers are connected by, for example, bolts and that contains an inflatable bag therein for preventing water intrusion (Patent Literature <NUM>: <CIT> Pamphlet). In Patent Literature <NUM>, each module unit includes a platform and a side wall for containing air and providing buoyancy, and adjacent module units are connected in a movable manner by using an air feeding mechanism and a hinge mechanism.

Patent literature <NUM>: <CIT>) shows a multi-component pneumatic floating platform according to the preamble of claim <NUM>.

However, in each of the pneumatic floating structures described in Patent Literatures <NUM> to <NUM> described above, the air chambers are exposed to water, so that the air in the air chambers is compressed due to the wave motions. This may cause the air to dissolve readily in the water, and is disadvantageous in terms of a decrease in buoyancy that may occur due to the air dissolving in the water. Moreover, a hinge-connected floating platform having a high degree of freedom may be problematic in terms of tilting and unstableness of a superstructure.

Furthermore, the floating-city floating structure described above in Patent Literature <NUM> and the artificial floating island described above in Patent Literature <NUM> are both not suitable for city-scale infrastructure construction, and are problematic in terms of, for example, a lack of spaces for accommodating lifeline infrastructure important for maintaining normalcy in daily life.

For the challenge of solving the aforementioned problems and building a floating city, an object of the present invention is to provide a multi-component pneumatic floating platform that can reduce rocking even in waves, can reduce tilting caused by strong winds, can prevent air within an air chamber from dissolving in water, and can be readily constructed, and also to provide floating offshore wind turbine equipment equipped with such a multi-component pneumatic floating platform.

In order to solve the aforementioned problems, the present invention provides a multi-component pneumatic floating platform including a plurality of floating module units and a connection unit. Each of the floating module units includes a shell and an air chamber provided inside the shell. The shell has an open bottom and is surrounded by a horizontal top wall and a side wall extending downward from a peripheral edge of the top wall. The connection unit connects adjacent floating module units of the plurality of the floating module units arranged in a horizontal direction. Each of the floating module units has a flexible membrane that divides the air chamber into an air layer and a water layer.

The membrane is installed in a loose state so that the membrane can conform to the wave of the water layer. Preferably, the flexible membrane seals the air layer hermetically. A peripheral edge of the membrane in a loose state may be joined to the side wall of the shell. The floating module unit may have a pressure adjustment unit configured to adjust air pressure in the air layer within the air chamber. The connection unit may be a 3D truss beam. The connection unit may be rigid and have a rigid structure. The connection unit may have an accommodation space for lifeline infrastructure.

Furthermore, a floating offshore wind turbine equipment includes the aforementioned multi-component pneumatic floating platform. Moreover, the multi-component pneumatic floating platform may have a moonpool surrounded by the floating module units and a turret-type mooring device installed in the moonpool. The turret-type mooring device may have a ball bearing whose outer periphery is coupled to the floating module unit disposed around the moonpool and that rotatably supports the multi-component pneumatic floating platform, and a cylindrical column that is detachably held by an inner periphery of the ball bearing and that is connected to a mooring line.

The multi-component pneumatic floating platform floating on a water surface according to the present invention employs the aforementioned configurations, so that a stable city-scale multi-component pneumatic floating platform with reduced wave-induced rocking and wind-induced tilting can be constructed inexpensively.

Furthermore, the multi-component pneumatic floating platform according to the present invention can be constructed on-site by connecting the plurality of floating module units by using a connection unit, such as a 3D truss beam. In addition, after the multi-component pneumatic floating platform is constructed, the number of floating module units can be increased or decreased as appropriate, and a removed floating module unit is reusable at another site.

Furthermore, the multi-component pneumatic floating platform according to the present invention can be used in floating offshore wind turbine equipment, so as to have both high dynamic stability against waves and high static stability against strong winds.

Specific embodiments of a multi-component pneumatic floating platform according to the present invention will now be described with reference to the drawings that illustrate the embodiments.

In <FIG>, reference sign <NUM> denotes a multi-component pneumatic floating platform floating on a water surface W and disposed away from a bottom B of the water, reference sign <NUM> denotes each floating module unit having an open bottom and provided with an air chamber <NUM> therein, reference sign <NUM> denotes each rigid connection unit connecting a plurality of adjacent floating module units <NUM> to establish the multi-component pneumatic floating platform <NUM>, and reference sign <NUM> denotes each building, such as an architectural structure, erected on the multi-component pneumatic floating platform <NUM>.

As shown in <FIG> and <FIG>, each floating module unit <NUM> includes a flat polygonal floor <NUM>, a lattice-like flange <NUM> on which the floor <NUM> is placed, a shell <NUM> that has a top surface above which the floor <NUM> is placed with the flange <NUM> interposed therebetween, is surrounded by a top wall <NUM> and a side wall <NUM> extending downward from the peripheral edge of the top wall <NUM>, and has an open bottom, a seal cover <NUM> that is surrounded by an upper wall <NUM> and a peripheral wall <NUM> extending downward from the peripheral edge of the upper wall <NUM> and that is attached inside the shell <NUM>, and a flexible membrane <NUM> that is joined to the air chamber <NUM> within the seal cover <NUM>.

Although the flange <NUM> is placed on the top surface of the shell <NUM> and the floor <NUM> is placed on the flange <NUM> in this embodiment, the floor <NUM> and the flange <NUM> may be installed as necessary. The buildings <NUM> may be erected directly on the top wall <NUM> if the shell <NUM> has sufficient strength. Furthermore, although the side wall <NUM> of the shell <NUM> is inclined outward from the peripheral edge of the top wall <NUM>, the side wall <NUM> may extend downward orthogonally from the peripheral edge of the top wall <NUM>.

Moreover, the floor <NUM> and the shell <NUM> may be manufactured by using a material, such as wood, steel, fiber-reinforced plastic (FRP), or concrete.

As shown in <FIG>, the air chamber <NUM> of the floating module unit <NUM> is divided into an air layer and a water layer by the membrane <NUM> composed of a flexible material. The flexible material is, for example, polyester or polypropylene and has functions for conforming to the surface of the water layer and for forming an interface between the air layer and the water layer.

In order to conform to the wave, a joint section 14a at the peripheral edge of the membrane <NUM> in a loose state is joined to the peripheral wall <NUM> of the seal cover <NUM> so that an impact of a wave force is alleviated, thereby suppressing tilting of the floating module unit <NUM>.

The seal cover <NUM> does not have to be attached so long as the interior of the shell <NUM> is hermetically sealed. In that case, the joint section 14a at the peripheral edge of the membrane <NUM> may be joined to the side wall <NUM> of the shell <NUM>.

Referring to <FIG>, in order to attach the membrane <NUM> that forms the air chamber <NUM> within the shell <NUM> (or the seal cover <NUM>) of the floating module unit <NUM>, the joint section 14a of the membrane <NUM> may be joined to the top end of the side wall <NUM>, as shown in <FIG>, the joint section 14a of the membrane <NUM> may be joined to the bottom end of the side wall <NUM>, as shown in <FIG>, or the joint section 14a of the membrane <NUM> may be joined to an intermediate portion of the side wall <NUM>, as shown in <FIG>.

As an alternative to the examples shown in <FIG> in which the membrane <NUM> has the joint section 14a provided at the free peripheral edge, the membrane <NUM> may be closed in the form of a bag and may be joined to the inner side of the shell <NUM> (or the seal cover <NUM>) via the joint section 14a, as shown in <FIG>.

Furthermore, as an alternative to this embodiment in which the joint section 14a of the membrane <NUM> is bonded to the inner side of the side wall <NUM> or the top wall <NUM> by using, for example, an adhesive, the joint section 14a may be fixed to securing members (not shown) evenly spaced apart from each other on the inner side of the side wall <NUM>, and the peripheral edge of the membrane <NUM> does not have to be in close contact with the side wall <NUM>.

Furthermore, as shown in <FIG>, as a pressure adjustment unit <NUM> that adjusts air pressure <NUM> in the air layer within the air chamber <NUM>, the floating module unit <NUM> includes an air pump <NUM> that compresses the air and an air delivery pipe <NUM> that supplies the compressed air from the air pump <NUM> to the air layer within the air chamber <NUM>.

The pressure adjustment unit <NUM> adjusts the air pressure <NUM> in the air layer within the air chamber <NUM> so as to balance out the air pressure <NUM> and water pressure <NUM>, thereby adjusting the buoyancy of the floating module unit <NUM>. Although not shown, each floating module unit <NUM> shown in <FIG> is individually provided with a pressure adjustment unit similar to that in <FIG>.

Each connection unit <NUM> is specifically formed of a rigid structural member, such as a steel 3D truss beam shown in <FIG> and <FIG>. As shown in <FIG>, a space provided in each connection unit <NUM>, such as a 3D truss beam, is used as a space for accommodating lifeline infrastructure 4a, such as a water pipe, a gas pipe, and an electric cable.

Furthermore, as shown in <FIG>, the connection units <NUM> rigidly couple the floating module units <NUM> to one another and also bend in response to a large force to increase stability by reducing wave-induced rocking and wind-induced tilting of the floating module units <NUM>, thereby solving problems such as tilting and unstableness of the buildings <NUM> to be erected on the multi-component pneumatic floating platform <NUM>.

Next, the usage and the advantages of this embodiment will be described.

Referring to <FIG>, the multi-component pneumatic floating platform <NUM> according to this embodiment can be mass-produced readily by manufacturing floating module units <NUM>, each having the assembly structure shown in <FIG>, at a factory in a step shown in <FIG>. In that case, the shell <NUM> may be manufactured by using precast concrete or by press-working a steel plate.

Subsequently, in a step shown in <FIG>, the plurality of floating module units <NUM> are stacked and are transported to a construction site. In a step shown in <FIG>, after the plurality of floating module units <NUM> are floated on the water surface W at the construction site, adjacent floating module units <NUM> are coupled together by using the connection units <NUM>, such as 3D truss beams, whereby the multi-component pneumatic floating platform <NUM> is constructed, as shown in <FIG>. Subsequently, the buildings <NUM> are erected on the multi-component pneumatic floating platform <NUM>.

As shown in <FIG>, when the buildings <NUM> are to be erected on the multi-component pneumatic floating platform <NUM>, the floating module units <NUM> can each cause the pressure adjustment unit (not shown) to adjust the air pressure <NUM> in the air layer within the air chamber <NUM>, thereby balancing out the air pressure <NUM> and the water pressure <NUM> and adjusting the buoyancy. Thus, each floating module unit <NUM> can flexibly cope with conditions of, for example, the buildings <NUM> on the multi-component pneumatic floating platform <NUM> and heavy equipment used during the construction.

In detail, in the case of the multi-component pneumatic floating platform <NUM> shown in <FIG>, the air pressure <NUM> in the air layers of the respective floating module units <NUM> can be adjusted with the pressure adjustment units in view of the load from the buildings <NUM> such that the air layers in the respective floating module units <NUM> increase in thickness in the following order starting from the smallest thickness: h1, h2, h4, and h3.

Accordingly, the multi-component pneumatic floating platform <NUM> according to this embodiment can be constructed by floating the plurality of floating module units <NUM> on the water surface W and coupling adjacent floating module units <NUM> together by using the connection units <NUM>, so that the number of floating module units <NUM> can be increased or decreased as appropriate, and a removed floating module unit <NUM> is relocatable and reusable.

Furthermore, since the buildings <NUM> serving as architectural structures to be erected on the multi-component pneumatic floating platform <NUM> are not in contact with the ground, the buildings <NUM> are less likely to be affected by earthquakes.

As shown in <FIG>, the spaces formed by the connection units <NUM>, such as 3D truss beams, to be used as couplers in the multi-component pneumatic floating platform <NUM> can each be utilized as a space for accommodating the lifeline infrastructure 4a, such as a water pipe, a gas pipe, and an electric cable, so that it is not necessary to newly ensure an accommodation space for the lifeline infrastructure 4a.

Next, a second embodiment in which the multi-component pneumatic floating platform <NUM> is used as a floating structure of floating offshore wind turbine equipment will be described.

In the following description, components identical to those in the first embodiment will be given the same reference signs, and the differences from the first embodiment will be mainly described.

In <FIG>, reference sign <NUM> denotes each wind turbine equipped with a wind turbine generator and erected on the multi-component pneumatic floating platform <NUM> constituted of the floating module units <NUM> and the connection units <NUM>, reference sign <NUM> denotes a solar panel for photovoltaic power generation, reference sign <NUM> denotes each propulsion thruster provided at the bottom of the floating module units <NUM>, and reference sign <NUM> denotes a turret-type mooring device that moors the multi-component pneumatic floating platform <NUM> to the bottom B of the water by using a mooring line <NUM>. A power transmission cable required for transmitting generated electric power is extended to the terminal end of the multi-component pneumatic floating platform <NUM> via the accommodation spaces in the connection units <NUM> formed of, for example, 3D truss beams, and is subsequently connected to an underwater cable so as to transmit the generated electric power ashore.

The turret-type mooring device <NUM> is installed in a moonpool <NUM> surrounded by the floating module units <NUM> of the multi-component pneumatic floating platform <NUM>. The turret-type mooring device <NUM> is constituted of a ball bearing <NUM> whose outer periphery is coupled to the floating module unit <NUM> disposed around the moonpool <NUM> and that rotatably supports the multi-component pneumatic floating platform <NUM>, and a cylindrical column <NUM> that is detachably held by the inner periphery of the ball bearing <NUM> and that is connected to the mooring line <NUM>.

The turret-type mooring device <NUM> is rigidly coupled to the floating module unit <NUM> disposed around the moonpool <NUM> by using, for example, a beam (not shown).

The floating module unit <NUM> disposed at the outer side of the turret-type mooring device <NUM> is provided with a lock mechanism <NUM> that engages with the cylindrical column <NUM> to inhibit rotation of the multi-component pneumatic floating platform <NUM>, so that the multi-component pneumatic floating platform <NUM> is prevented from rotating freely around the turret-type mooring device <NUM> due to a tidal current or a wind force.

With regard to the floating offshore wind turbine equipment according to this embodiment, the multi-component pneumatic floating platform <NUM> is first constructed by performing a process similar to that for the multi-component pneumatic floating platform <NUM> according to the first embodiment shown in <FIG> such that the moonpool <NUM> surrounded by any one of the floating module units <NUM> is formed. Subsequently, the turret-type mooring device <NUM> is installed in the moonpool <NUM> via, for example, a beam (not shown), and the turret-type mooring device <NUM> is moored to the bottom B of the water by using the mooring line <NUM>.

Then, the wind turbines <NUM> and the solar panel <NUM> are installed on specific floating module units <NUM> in view of the load to be applied to the multi-component pneumatic floating platform <NUM>, and the power transmission cable for transmitting electric power generated by the wind turbines <NUM> is accommodated in the accommodation spaces of the connection units <NUM>, whereby the floating offshore wind turbine equipment equipped with the multi-component pneumatic floating platform <NUM> is completed.

In the floating offshore wind turbine equipment according to this embodiment, the plurality of propulsion thrusters <NUM> are arranged at the bottom of the floating module units <NUM> in a well-balanced manner, so that when the lock mechanism <NUM> releases the locked state of the turret-type mooring device <NUM>, the multi-component pneumatic floating platform <NUM> can rotate freely around the turret-type mooring device <NUM>, whereby the rotation of the multi-component pneumatic floating platform <NUM> on which the wind turbines <NUM> is installed can be controlled in accordance with the wind direction.

In this case, the electric power generated by the solar panel <NUM> or by the wind force can be used as a power source for an electric motor that rotationally drives each thruster <NUM>.

Furthermore, in an emergency situation, such as during a typhoon, evacuation of the floating offshore wind turbine equipment is possible by removing the cylindrical column <NUM> from the turret-type mooring device <NUM> and towing the floating offshore wind turbine equipment to a safe location.

Moreover, since the floating offshore wind turbine equipment is moored to a single spot at the bottom B of the water by using the turret-type mooring device <NUM>, there is no risk of entanglement of the mooring line <NUM>.

Accordingly, with the floating offshore wind turbine equipment equipped with the multi-component pneumatic floating platform <NUM> according to this embodiment, the multi-component pneumatic floating platform <NUM> has stability against waves and strong winds and is rotatable and movable if necessary, thereby enabling stable electric power generation in accordance with various weather conditions.

Claim 1:
A multi-component pneumatic floating platform (<NUM>) comprising:
a plurality of floating module units (<NUM>), each of plurality of floating module units (<NUM>) including a shell (<NUM>) and an air chamber (<NUM>) provided inside the shell (<NUM>), the shell (<NUM>) having an open bottom and being surrounded by a horizontal top wall (<NUM>) and a side wall (<NUM>) extending downward from a peripheral edge of the top wall (<NUM>); and
a connection unit (<NUM>) that connects adjacent floating module units (<NUM>) of a plurality of the floating module units (<NUM>) arranged in a horizontal direction, wherein
each of the floating module units (<NUM>) has a flexible membrane (<NUM>), the multi-component pneumatic floating platform being characterised in that the membrane of each floating module units divides the air chamber (<NUM>) into an air layer and a water layer, and in that
the membrane (<NUM>) is installed in a loose state.