Method for installing concrete structure on seabed

Abstract

According to the present invention, when installing a concrete structure that is closed on the bottom and open on the top and has an inner space on a seabed, a temporary cover is installed on the concrete structure to seal the inner space, and the buoyancy of the inner space is used to bring the concrete structure to a state of negative buoyancy very close to neutral buoyancy (i.e., bring the actual weight thereof close to zero), thus obviating the need for a large crane for supporting the weight of the concrete structure when sinking the concrete structure.

Description

Method of installing concrete structures on the seabed

[0001] The present invention relates to a method for installing a concrete structure having an internal space with a closed lower surface and an open upper surface on a seabed.

[0002] Various concrete structures are installed on the seabed.

[0003] As the simplest example, a caisson-shaped concrete structure can be installed on the seabed to build a breakwater or the like.

[0004] Additionally, concrete structures with gravity-based foundations can be installed on the seabed as fixed bottom foundations for offshore wind farms.

[0005] Concrete structures are generally cheaper to manufacture than metal structures, but they are very heavy. This weight issue makes them extremely difficult to install offshore as concrete structures become larger.

[0006] The gravity foundation (concrete structure) of the fixed foundation for an offshore wind power generation facility for an 8MW wind turbine designed by the applicant weighs approximately 6,000 tons.

[0007] In addition, as the turbine capacity of offshore wind power generation increases, the gravity foundation also needs to be larger.

[0008] It is practically impossible to lift a 6,000-ton concrete structure from the sea with a crane and sink it to the seabed.

[0009] For reference, the Goliath crane, known as a large crane on land, is known to be able to lift up to 1000 tons.

[0010] The present invention has been devised to solve the problems of the prior art as described above, and when installing a concrete structure having an internal space with a closed lower surface and an open upper surface on the seabed, a temporary cover is installed on the concrete structure to seal the internal space, and the buoyancy of the internal space is utilized to install the concrete structure, thereby solving the problem caused by the weight of the concrete structure.

[0011] In order to solve the above problem, the present invention is characterized by including a concrete structure manufacturing step of manufacturing a concrete structure having an internal space with a closed lower surface and an open upper surface; a floating step of floatation of the concrete structure on the water surface by utilizing buoyancy of the internal space of the concrete structure; a temporary cover installation step of sealing the internal space by covering the open upper surface of the internal space with a temporary cover having a pipe for the internal space provided therein; a transport step of transporting the concrete structure floating on the water surface to an installation location using a tugboat in a state of being floated on the water surface; a sinking step of injecting water into the internal space through the pipe for the internal space of the temporary cover after the transport step and the temporary cover installation step so that the concrete structure sinks to the seabed while a portion of the internal space is filled with water; and a temporary cover removal step of removing the temporary cover from the concrete structure after the sinking step.

[0012] In another aspect of the present invention, the present invention is characterized by comprising: a concrete structure manufacturing step for manufacturing a concrete structure having an internal space with a closed lower surface and an open upper surface, and a seawater distribution port for connecting the lower portion of the internal space to the outside; a temporary cover installation step for sealing the internal space by covering the open upper surface of the internal space with a temporary cover having a pipe for the internal space; a floating step for injecting compressed air into the internal space through the pipe for the internal space of the temporary cover so that a portion of the internal space is filled with the compressed air, thereby floating the concrete structure on the water surface; a transport step for transporting the concrete structure floating on the water surface to an installation location using a tugboat; after the transport step, a sinking step for sinking the concrete structure to the seabed by discharging a portion of the compressed air of the internal space to the outside through the pipe for the internal space of the temporary cover and allowing seawater to flow in through the seawater distribution port; and a temporary cover removal step for removing the temporary cover from the concrete structure after the sinking step.

[0013] In the above, it is preferable that a watertight packing is provided on the lower surface of the temporary cover to seal the internal space.

[0014] In the above, after the temporary cover removal step, a filling material filling step of filling the internal space of the concrete structure with a filling material may be further included.

[0015] In the above, in the sinking step, it may be desirable to increase the pressure of the internal space by injecting compressed air into the internal space through a pipe for the internal space of the temporary cover according to the depth of the concrete structure being sunk.

[0016] As described above, the present invention, when attempting to install a concrete structure having an internal space with a closed bottom and an open top on the seabed, installs a temporary cover on the concrete structure to seal the internal space and uses the buoyancy of the internal space to make the concrete structure negatively buoyant, which is very close to neutral buoyancy (i.e., makes the actual weight close to 0), so that a large crane to support the weight of the concrete structure is unnecessary when sinking the concrete structure.

[0017] In other words, when lowering a concrete structure, it is sufficient to guide the position or settling location of the concrete structure using a small crane or barge equipped with a winch that can support relatively light weight.

[0018] Therefore, the present invention makes it possible to install a concrete structure on the seabed at a very low cost.

[0019] In addition, according to the present invention, even if the weight of the concrete structure increases, it can be easily installed on the seabed.

[0020] Figures 1 to 7 are drawings showing the sequence of a method for installing a concrete structure on the seabed according to the first embodiment of the present invention.

[0021] Figures 8 to 11 are drawings showing the sequence of a method for installing a concrete structure on the seabed according to a second embodiment of the present invention.

[0022] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, irrelevant parts have been omitted for clarity of description, and similar reference numerals have been assigned to similar parts throughout the specification.

[0023] Throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0024] Hereinafter, a method for installing a concrete structure on a seabed according to a first embodiment of the present invention will be described in detail.

[0025] 1. Concrete structure manufacturing stage

[0026] As shown in Fig. 1, a concrete structure (100) having an internal space (110) with a closed lower surface and an open upper surface is manufactured.

[0027] The inventor of the present invention has proposed a technology for manufacturing a floating concrete block structure in which concrete blocks are joined underwater, as disclosed in Korean Patent Registration No. 10-2292821, and in this embodiment, the above-mentioned conventional technology is applied to manufacture a concrete structure (100) underwater.

[0028] Therefore, in this embodiment, the internal space (110) is filled with water at the same level as the external water level.

[0029] In some embodiments, the concrete structure (100) may be manufactured on land.

[0030] A plurality of connecting bolts (120) are arranged on the upper part of the concrete structure (100) in a form that surrounds the internal space (110).

[0031] In this embodiment, the internal space (110) is illustrated as being formed in one piece, but the internal space (110) may be formed in multiple pieces, and the shape of the concrete structure (100) can be modified in many different ways.

[0032] 2. Floating stage

[0033] After Fig. 1, as shown in Fig. 2, the concrete structure (100) is floated on the water surface by utilizing the buoyancy of the internal space (110) of the concrete structure (100). That is, when the water in the internal space (110) is drained to the outside, the concrete structure (100) floats on the water surface by the buoyancy of the internal space (110).

[0034] If a concrete structure (100) is manufactured on land, it is possible to float the concrete structure (100) on the water surface without separate drainage work.

[0035] 3. Temporary cover installation step

[0036] After Fig. 2, as shown in Fig. 3, a temporary cover (200) is installed on the concrete structure (100).

[0037] Specifically, the open upper surface of the internal space (110) of the concrete structure (100) is covered with a temporary cover (200) to seal the internal space (110).

[0038] A temporary cover (200) is provided with a pipe (201) for the internal space.

[0039] The pipe (201) for the internal space is a pipe formed to inject water or air into the internal space (110) or discharge air from the internal space (110), and includes a valve, etc.

[0040] A watertight packing (202) is provided on the lower surface of the temporary cover (200) to seal the internal space (110).

[0041] After placing the temporary cover (200) on top of the concrete structure (100) so that the connecting bolt (120) provided in the concrete structure (100) passes through the bolt penetration hole formed in the temporary cover (200), a nut is tightened on the connecting bolt (120) to secure the temporary cover (200) to the concrete structure (100).

[0042] In this way, the watertight packing (202) is compressed between the temporary cover (200) and the concrete structure (100) to prevent water from flowing into the inner space (110) from the outside.

[0043] The temporary cover (200) may be installed immediately after the concrete structure (100) is manufactured, or may be installed immediately before the settling step described below.

[0044] Meanwhile, in this embodiment, the watertight packing (202) is described as being provided on a temporary cover (200), but depending on the embodiment, the watertight packing may be provided on the upper part of the concrete structure (100).

[0045] 4. Transport stage

[0046] After Fig. 3, as shown in Fig. 4, the concrete structure (100) floating on the water surface is transported to the installation site using a tugboat while floating on the water surface.

[0047] That is, the concrete structure (100) of this embodiment is not transported by being loaded onto a barge or the like.

[0048] 5. Sedimentation stage

[0049] After being transported to the installation location as shown in Fig. 4, water is injected into the internal space (110) of the concrete structure (100) through the pipe (201) for the internal space of the temporary cover (200) as shown in Fig. 5, so that the concrete structure (100) is sunk to the seabed while a portion of the internal space (110) is filled with water.

[0050] That is, when water is injected into the internal space (110) to make the concrete structure (100) in a negative buoyancy state very close to neutral buoyancy, the actual weight of the concrete structure (100) becomes close to 0 and it has the property of sinking very slowly.

[0051] Specifically, a portion of the internal space (110) is filled with water, but the remaining portion of the internal space (110) is still filled with air.

[0052] That is, the air filled in the inner upper part of the inner space (110) provides buoyancy sufficient to compensate for most of the weight of the concrete structure (100).

[0053] Additionally, during the sedimentation process, water does not flow into the internal space (110) due to the watertight packing (202).

[0054] Therefore, in this embodiment as well, a sinking guide device (such as a crane or a barge equipped with a winch) connected to the concrete structure (100) by a wire rope, etc., may be required for sinking the concrete structure (100), but it is sufficient if the sinking guide device can support a very light weight, and furthermore, the sinking guide device is used for guiding the posture or settling position of the concrete structure rather than supporting the weight of the concrete structure.

[0055] Meanwhile, according to an embodiment, if the depth of the seabed is deep, the internal pressure of the internal space (110) can be increased by injecting compressed air into the internal space (110) through the internal space pipe (201) according to the depth of the concrete structure (100) that is sinking.

[0056] As the water depth increases, the pressure (water pressure) at that depth increases. In other words, for every 10m increase in water depth, the water pressure increases by approximately 1kgf / cm2.

[0057] If a concrete structure (100) is installed at a water depth of 100 m, the walls of the concrete structure (100) must be designed to withstand a pressure of approximately 10 kgf / cm2 (corresponding to the pressure at a water depth of 100 m). However, such a design is only necessary for installation and is unnecessary in actual use.

[0058] Therefore, by injecting compressed air into the internal space (110) every 20 m of water depth to increase the pressure of the internal space (110) to 2 kgf / cm2 (20 m water depth), 4 kgf / cm2 (40 m water depth), 6 kgf / cm2 (60 m water depth), and 8 kgf / cm2 (80 m water depth), the pressure of the compressed air in the internal space (110) compensates for the external water pressure, so it is sufficient for the wall of the concrete structure (100) to be designed to withstand a pressure of approximately 2 kgf / cm2.

[0059] In addition, depending on the embodiment, by injecting compressed air into the internal space (110) every 10 m of water depth to increase the pressure of the internal space (110) to 1, 2, 3, 4, 5, 6, 7, 8, 9 kgf / cm2, it is sufficient for the wall of the concrete structure (100) to be designed to withstand a pressure of about 1 kgf / cm2.

[0060] In this way, by injecting compressed air into the internal space (110) according to the water depth, the external water pressure is compensated for by the pressure of the compressed air inside the internal space (110), so there is no need to design the wall of the concrete structure (100) to be thick.

[0061] 6. Step 6: Remove the temporary cover

[0062] After Fig. 5, the temporary cover (200) is removed from the concrete structure (100) as shown in Fig. 6.

[0063] That is, after the internal space (110) is filled with seawater by allowing seawater to flow into the internal space (110) through the pipe (201) for the internal space (i.e., after the internal air is discharged), the nut connected to the connecting bolt (120) is loosened and the temporary cover (200) is separated from the concrete structure (100) and removed.

[0064] For this purpose, a ring (not shown) or the like may be provided on the temporary cover (200).

[0065] The removed temporary cover (200) can be used for the installation of another concrete structure (100).

[0066] 7. Filling the filling material step

[0067] After Fig. 6, the internal space (110) of the concrete structure (100) can be filled with a filling material (140) such as sand or gravel, as shown in Fig. 7.

[0068] As described above, the installation of the temporary cover (200) on the concrete structure (100) is done by using a combination of a connecting bolt (120) and a nut. However, depending on the embodiment, the temporary cover (200) can be installed on the concrete structure (100) by its own weight and the watertight packing (202) can be compressed without using a separate connecting bolt and nut.

[0069] Below, a method for installing a concrete structure on a seabed according to a second embodiment of the present invention is described in detail.

[0070] In the following, descriptions of parts that are the same as those in the first embodiment are omitted.

[0071] 1. Concrete structure manufacturing stage

[0072] As shown in Fig. 8, a concrete structure (100) is manufactured that has an internal space (110) with a closed bottom and an open top, and a seawater distribution port (130) that connects the lower part of the internal space (110) to the outside.

[0073] 2. Temporary cover installation step

[0074] After Fig. 8, as shown in Fig. 9, a temporary cover (200) is installed on the concrete structure (100).

[0075] 3. Floating stage

[0076] After Fig. 9, as shown in Fig. 10, compressed air is injected into the internal space (110) through the pipe (201) for the internal space of the temporary cover (200), so that a part (upper part) of the internal space (110) is filled with compressed air, thereby floating the concrete structure (100) on the water surface.

[0077] That is, when compressed air is injected into the internal space (110), the water inside the internal space (110) is discharged to the outside through the seawater distribution port (130) due to the pressure of the compressed air, and thus the water level inside the internal space (110) becomes lower than the water level outside, and the concrete structure (100) floats on the water surface due to the buoyancy of the internal space (110) generated as a result.

[0078] 4. Transport stage

[0079] After Fig. 10, the concrete structure (100) floating on the water surface is transported to the installation site using a tugboat while floating on the water surface.

[0080] 5. Sedimentation stage

[0081] After being transported to the installation site, as shown in Fig. 11, a portion of the compressed air in the internal space (110) is discharged to the outside through the pipe (201) for the internal space of the temporary cover (200), and seawater is allowed to flow in through the seawater distribution port (130) to cause the concrete structure (100) to sink to the seabed.

[0082] That is, by causing the internal water level of the internal space (110) to rise as the compressed air is discharged, so that the concrete structure (100) is in a negative buoyancy state very close to neutral buoyancy, the actual weight of the concrete structure (100) becomes close to 0 and it has the property of sinking very slowly.

[0083] For this purpose, a part (lower part) of the internal space (110) is filled with water, but the remaining part (upper part) of the internal space (110) is still filled with compressed air.

[0084] That is, the compressed air filled in the inner upper part of the inner space (110) provides buoyancy sufficient to compensate for most of the weight of the concrete structure (100).

[0085] Meanwhile, depending on the depth of the sinking concrete structure (100), it may be desirable to increase the internal pressure of the internal space (110) by injecting more compressed air into the internal space (110) through the internal space pipe (201).

[0086] Air is compressed as pressure increases, and as the water depth increases, the water pressure increases, so as the water depth increases, the volume occupied by the compressed air in the internal space (110) decreases, which leads to a decrease in buoyancy.

[0087] Therefore, even when the water depth increases, it is necessary to additionally inject compressed air into the internal space (110) so that the volume occupied by the compressed air in the internal space (110) is maintained (i.e., so that the buoyancy of the internal space (110) is maintained as is).

[0088] 6. Temporary cover removal step and filling step

[0089] After Fig. 11, the temporary cover (200) is removed from the concrete structure (100), and the internal space (110) of the concrete structure (100) can be filled with a filling material (140) such as sand or gravel.

[0090] The scope of the present invention is indicated by the claims set forth below rather than the detailed description above.

[0091] The present invention can be used to install a large concrete structure having an internal space with a closed lower surface and an open upper surface on the seabed.

Claims

1. Concrete structure manufacturing step: Manufacturing a concrete structure with an internal space that is closed at the bottom and open at the top: A floating step of floating the concrete structure on the water surface by utilizing the buoyancy of the internal space of the concrete structure; A temporary cover installation step for sealing the internal space by covering the open upper surface of the internal space with a temporary cover having a pipe for the internal space; A transport step of transporting the concrete structure floating on the water surface to the installation site using a tugboat while floating on the water surface; After the above-mentioned transport step and the above-mentioned temporary cover installation step, a settling step in which water is injected into the internal space through a pipe for the internal space of the temporary cover, thereby settling the concrete structure to the seabed while a portion of the internal space is filled with water; A temporary cover removal step of removing the temporary cover from the concrete structure after the above settling step; A method for installing a concrete structure on a seabed, characterized in that it includes a .

2. In paragraph 1, A method for installing a concrete structure on the seabed, characterized in that a watertight packing for sealing the internal space is provided on the lower surface of the temporary cover.

3. In paragraph 1, A method for installing a concrete structure on a seabed, characterized in that it further includes a filling material filling step of filling the internal space of the concrete structure with a filling material after the temporary cover removal step.

4. In paragraph 1, A method for installing a concrete structure on the seabed, characterized in that, in the sinking step, compressed air is injected into the internal space through a pipe for the internal space of the temporary cover according to the depth of the concrete structure being sunk, thereby increasing the pressure of the internal space.

5. Concrete structure manufacturing step for manufacturing a concrete structure having an internal space with a closed bottom and an open top, and a seawater distribution port that connects the lower part of the internal space to the outside: A temporary cover installation step for sealing the internal space by covering the open upper surface of the internal space with a temporary cover having a pipe for the internal space; A floating step of injecting compressed air into the internal space through a pipe for the internal space of the temporary cover, thereby filling a portion of the internal space with compressed air, thereby floating the concrete structure on the water surface; A transport step of transporting the concrete structure floating on the water surface to the installation site using a tugboat while floating on the water surface; After the above transport step, a settling step of discharging a portion of the compressed air in the internal space of the temporary cover to the outside through a pipe for the internal space of the temporary cover and allowing seawater to flow in through the seawater distribution port to cause the concrete structure to sink to the seabed; A temporary cover removal step of removing the temporary cover from the concrete structure after the above settling step; A method for installing a concrete structure on a seabed, characterized in that it includes a .

6. In paragraph 5, A method for installing a concrete structure on the seabed, characterized in that a watertight packing for sealing the internal space is provided on the lower surface of the temporary cover.

7. In paragraph 5, A method for installing a concrete structure on a seabed, characterized in that it further includes a filling material filling step of filling the internal space of the concrete structure with a filling material after the temporary cover removal step.

8. In paragraph 5, A method for installing a concrete structure on the seabed, characterized in that, in the sinking step, compressed air is injected into the internal space through a pipe for the internal space of the temporary cover according to the depth of the concrete structure being sunk, thereby increasing the pressure of the internal space.

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