JP4819835B2 - Offshore structure and construction method of offshore structure - Google Patents

Description

  The present invention relates to an offshore structure using a caisson or a cellular block, which is used as a seawall or breakwater in a coast or a river, and a construction method of the offshore structure.

  When constructing facilities on land near a coast or river, or in a landfill site that reclaims the coast, conventionally, a seawall or breakwater is often laid to prevent inflow of seawater such as waves from the sea. For example, when constructing a large facility such as a power plant, the revetment is required to have durability against waves, earthquake resistance against disasters such as earthquakes, and water stoppage that may block the inflow of seawater. As a structure satisfying such a requirement, the present applicants previously proposed a caisson type offshore structure shown in Patent Document 1.

Hereinafter, the outline | summary of the caisson type offshore structure of patent document 1 is demonstrated.
FIG. 8 is a side sectional view showing a configuration of a caisson type offshore structure according to the prior art, and FIG. 9 is a perspective view schematically showing a lower structure.
As shown in FIG. 8 and FIG. 9, a box-shaped caisson 1 having an open upper surface is disposed on a caisson-type revetment (an offshore structure) constructed in a sea area. The caisson 1 is provided so that the upper part is exposed from the sea surface, and seawater is prevented from flowing from the sea side A to the back side B by waves or the like.

  In the lower part of the caisson 1, a formwork having a certain region is formed by a steel pipe pile 21 driven into the bedrock of the seabed and a plate-like steel formwork 16 formed in the pitch dimension of the steel pipe pile 21. The lower concrete 17 is placed in this region. Further, a caisson installation base 18 and a shear key concrete are respectively provided on the upper portion of the placed lower concrete 17.

  When installing a caisson type offshore structure, first, the rock in the place where the caisson 1 is installed is excavated over a predetermined width. And the steel pipe pile 21 for formwork support is driven using the pile driving machine on a marine work bench. A plurality of the steel pipe piles 21 are arranged in two rows on the sea side A and the back side B of the excavated portion, and are placed at a predetermined pitch.

  Next, the steel molds 16 are set one by one between the adjacent steel pipe piles 21. In setting, the steel formwork 16 is suspended by a large crane and guided to the installation position on the seabed. Workers are waiting on the sea floor, and the guided steel mold 16 is guided and supported by the support hardware of the steel pipe pile 21 to perform the work of forming the mold. In addition, the sandbag 30 etc. are piled up and fixed to the outer surface of the steel formwork 16 in a place where a gap is generated between the steel formwork 31 and the rock due to ground inclination / non-landing to prevent the concrete from being washed away. .

  The lower concrete 17 and the shear key concrete are underwater inseparable concrete. First, the lower concrete 17 is cast into a mold to a predetermined height and solidified. And the caisson installation stand 18 is installed and fixed on this lower concrete 17, and also the caisson 1 is mounted correctly on it. By forming the lower concrete 17 in this way, the caisson 1 is installed on a stable foundation.

  Next, the filling material 13 and the filling concrete are placed in the caisson 1 from the upper opening surface. Then, after filling is completed, the top end is shaped and rolled, and the cover concrete 14 is placed. Further, secondary concrete is placed on the front and back surfaces of the caisson 1 to form a shear key concrete that is reinforced with reinforcing bars or the like and protrudes integrally from the lower concrete 17.

FIG. 10 is a front view and a plan view showing a configuration in which a cellular block is applied to an offshore structure according to the prior art.
Conventionally, when installing an offshore structure in a shallow water area, a cellular block 19 is applied instead of the caisson 1. That is, the marine structure is properly used for the caisson 1 and the cellular block 19 depending on the depth of the place where the marine structure is installed.

As shown in FIG. 10, the cellular block 19 is a block body in which concrete is formed in a square tube shape. The cellular blocks 19 are formed so as to have substantially the same shape and size, and are arranged in a plurality of rows and stacked in a plurality of stages according to the water depth.
JP 2001-40630 A

  Now, the assembly process of the caisson-type offshore structure of Patent Document 1 includes many processes in which workers work in the sea. For example, in the work of forming a mold, a worker performs a complicated work such as guiding a number of steel molds in the sea. When work such as forming a mold is performed in the sea, it has been greatly affected by seawater such as ocean currents and waves, causing a reduction in work efficiency.

  Moreover, the steel pipe pile of a caisson type offshore structure is driven in both the sea side and the back side in order to fix a formwork. Therefore, the formation of the caisson-type offshore structure form requires manufacturing a steel pipe pile using a large amount of iron material and placing a large number of steel pipe piles on the sea floor, and the manufacturing cost is very high.

  Furthermore, when the cellular block is applied in a shallow water area, the stacked blocks may be displaced due to water pressure such as ocean current before being fixed with concrete, which causes work to be delayed.

  The present invention has been made in view of the circumstances as described above, and can reduce a complicated work process in water, work can be efficiently performed, and can reduce production costs such as materials. The purpose is to provide.

  In order to solve the above-described problem, the present invention provides a marine structure including a caisson laid in the ocean and a caisson foundation structure provided on the seabed and serving as a foundation of the caisson. A plurality of steel pipe piles to be driven in, a caisson foundation unit that is assembled on the ground, fitted into a steel pipe pile and installed on the seabed, forming a fixed internal space as a formwork to support the caisson, and the interior of the caisson foundation unit And foundation concrete that is placed in a space and solidified as a caisson foundation structure.

  According to the marine structure having such a configuration, the caisson foundation unit is assembled in advance on land. The assembled caisson foundation unit can be easily installed on the seabed by fitting it into a steel pipe pile driven into the seabed. Therefore, the operator does not perform complicated work in the sea, and the marine structure can be installed more efficiently.

The caisson foundation unit may include a caisson frame formed of a metal material and a foundation mold provided on a side surface of the caisson frame.
Further, the caisson frame is a stage panel formed by arranging a plurality of metal materials in a substantially flat surface, a pedestal that stably supports the stage panel, a side block that is provided on a side surface of the stage panel and to which a basic formwork is attached, It can be set as the structure containing.

  The caisson foundation unit can be firmly formed as a form having an internal space by the caisson mount and the foundation form. For this reason, the caisson foundation unit will not be damaged even if water pressure such as ocean current is applied when it is installed on the seabed.

  Further, the gantry may be configured to include a leg length adjusting means capable of adjusting the length to the stage panel according to the shape of the seabed. The stage panel of the caisson base unit can be made substantially horizontal by adjusting the pedestal with the leg length adjusting means. Therefore, when foundation concrete is placed on the caisson foundation unit, the caisson foundation structure can be formed as a stable foundation.

  Moreover, a steel pipe pile can be set as the structure driven in a line at predetermined intervals along the laying path | route of a caisson. Furthermore, the caisson foundation unit can be configured to have an engagement portion into which the steel pipe pile is fitted at a substantially central position.

  The caisson foundation unit can stably support the caisson foundation unit by fitting the steel pipe pile at the center position. That is, it is not necessary to arrange steel pipe piles in two or more rows and drive them into the seabed in large quantities. Therefore, the number of steel pipe piles to be driven can be reduced, and the manufacturing cost can be reduced.

  In a region where the water depth from the caisson foundation structure to the sea surface is shallower than a certain depth, a cellular block having a size corresponding to the water depth can be installed on the caisson foundation structure instead of the caisson. With the cellular block having such a configuration, it is not necessary to stack the cellular blocks one by one. As a result, the worker can easily work in the sea and can be installed more efficiently.

  The construction method of the offshore structure of the present invention includes a step of driving a steel pipe pile into the seabed, a step of assembling the caisson foundation unit on land, a step of fitting the caisson foundation unit into the steel pipe pile, and an interior of the caisson foundation unit. The method includes the steps of placing a foundation concrete in a space to form a caisson foundation structure, and installing a caisson in the caisson foundation structure.

  The construction method of the offshore structure can be realized by a simple work process in which the caisson foundation unit is assembled in advance on land and the caisson foundation unit is fitted into a steel pipe pile driven in the sea.

  As described above, according to the present invention, complicated work processes in water can be reduced, work can be efficiently performed, and production costs such as materials can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 to FIG. 6 are views showing the configuration of the offshore structure according to the first embodiment of the present invention, and FIG. 1 is a side sectional view showing the outline of the entire configuration of the offshore structure.
The offshore structure of the first embodiment is an example applied to a case where it is installed on a coast as a revetment, and a power plant or the like is constructed by reclaiming the back surface thereof. In the first embodiment, a case where a caisson is applied will be described on the assumption that a revetment is laid in a relatively deep sea area.

  As shown in FIG. 1, the offshore structure of the first embodiment includes a caisson 1 laid in the ocean, and a caisson foundation that is provided on the sea floor as a base of the caisson 1 and stably arranges the caisson 1. The structure 2 is provided.

  Further, the offshore structure includes a foundation rubble 10 deposited extensively along the sea bottom A of the caisson 1, a covering block 11 covering the upper surface of the foundation rubble 10 in a plane, the caisson 1 and the base A wave-dissipating block 12 deposited on the sea side A surface of the rubble 10 with a certain inclination is also provided, and the entire revetment is constituted by these elements. With such a structure, the revetment can artificially reduce the depth of the sea area, and can suppress the amount of seawater from the ocean. Therefore, the revetment can more reliably block seawater from flowing from the sea side A to the back side B of the revetment due to waves or the like.

  The caisson 1 of the present embodiment uses a long reinforced concrete structure generally called an RC caisson. The caisson 1 is formed in a box shape whose upper surface is open, and the inside is partitioned into a plurality of blocks. At the time of assembling the offshore structure, filling material 13 such as earth and sand is injected into each block of the caisson 1. Thereafter, the upper surface opening of the caisson 1 is covered with the lid concrete 14 and the upper concrete 15 to form an offshore structure.

FIG. 2 is a perspective view showing the caisson foundation structure of the offshore structure according to the first embodiment, and FIG. 3 is a side sectional view showing the caisson foundation structure and the caisson. FIG. 4 is a perspective view showing a state in which the caisson foundation structure is fitted into the steel pipe pile.
As shown in FIGS. 2 and 3, the caisson foundation structure 2 includes a plurality of steel pipe piles 21 driven into the seabed and a caisson foundation unit 20 fitted into the steel pipe piles 21.

  The steel pipe piles 21 are formed of a rod-shaped steel material, and are arranged in a line at a predetermined interval along the caisson 1 laying path (see FIG. 4). The steel pipe pile 21 is completely fixed to the bedrock of the seabed and driven until the head reaches a certain height.

  The caisson foundation unit 20 is configured to be assembled on land. The caisson base unit 20 includes a caisson base 22 formed of a metal material and a base formwork 28 provided on a side surface of the caisson base 20. Moreover, the caisson foundation unit 20 is installed in the seabed by being fitted in the steel pipe pile 21.

  The caisson mount 22 is provided on a stage panel 23 formed by arranging a plurality of metal materials in a substantially flat surface, a pedestal 24 that stably supports the stage panel 23, and a side surface of the stage panel 23. And a side block 25 to be attached. The stage panel 23, the pedestal 24, and the side block 25 are all made of steel having an H-shaped cross section, which improves the strength of the caisson gantry 22 itself. Therefore, the caisson mount 22 can exhibit sufficient strength against water pressure due to ocean currents.

As shown in FIG. 4, the caisson mount 22 is provided with a simple hydraulic jack (leg length adjusting means) 26 that can adjust the length of the mount leg 24 according to the shape of the seabed. This simple hydraulic jack 26 can adjust the length of the pedestal 24 to make the stage panel 23 of the caisson gantry 22 horizontal.
Furthermore, the caisson mount 22 is provided with an engaging portion 27 into which the steel pipe pile 21 is fitted at a substantially central position. By this engaging portion 27, the balance is maintained when the caisson foundation unit 20 is fitted into the steel pipe pile 21, and the caisson mount 22 can be stably fixed.

The base formwork 28 of the caisson base unit 20 is a metallic plywood, and is provided on two sides of the caisson mount 22 on the sea side A and the back side B. Therefore, as shown in FIG. 4, the caisson foundation unit 20 includes a caisson frame 22 that continues along the laying path of the caisson 1, so that the foundation form frame 28 covers the side peripheral surface thereof, and a rectangular internal space 29 is formed. It will be formed on the sea floor.
In addition, the sandbag 30 is piled up on the outer peripheral surface of the foundation formwork 28 in the place where a clearance gap arises between the foundation formwork 28 and the seabed due to the ground inclination / unevenness.

  In the internal space 29 of the caisson foundation unit 20, a foundation concrete 31 that hardens the caisson foundation structure 2 is placed. The foundation concrete 31 is made of underwater inseparable concrete and can be solidified in the sea. By solidifying the caisson foundation structure 2 with the foundation concrete 31, a strong foundation on which the caisson 1 is installed can be formed.

FIG. 5 is a schematic diagram illustrating an assembly process of the offshore structure according to the first embodiment, and FIG. 6 is a perspective view illustrating an assembly process of the caisson foundation unit of the offshore structure.
In the offshore structure facility process, the ocean structure laying path on the sea floor is excavated with a rock crush bar, a hydraulic breaker, or the like. And as shown to Fig.5 (a), the steel pipe pile 21 is driven along the laying path | route of the marine structure of a seabed. The steel pipe piles 21 are driven in a line at intervals that engage with the engaging portions 27 of the caisson mount 22 using a pile driving machine on an offshore work table.

  Furthermore, the caisson basic unit 20 is assembled on land. As shown in FIG. 6A, the caisson mount 22 of the caisson base unit 20 is formed in a table shape by first attaching a pedestal 24 to a stage panel 23 formed in a plane. At this time, an engaging portion 27 into which the steel pipe pile 21 is fitted is provided at a substantially central position of the stage panel. Then, as shown in FIG.6 (b), the side block 25 is attached to the both sides | surfaces of a table, and the caisson mount frame 22 is assembled.

  Then, as shown in FIGS. 6C and 6D, the basic formwork 28 is attached to the side block 25 of the assembled caisson frame 22. The lower end portion of the foundation mold 28 is cut in advance in accordance with the shape of the seabed on which the caisson foundation unit 20 is installed. With this configuration, the caisson foundation unit 20 can form an internal space 29 according to the shape of the seabed.

  Next, as shown in FIG. 5 (b), the caisson foundation unit 20 assembled on land is towed to the laying position of the offshore structure by the dedicated ship. Further, the caisson foundation unit 20 carried to the laying position is gradually lowered to the seabed by a crane of a dedicated ship. Workers are waiting on the seabed, and the caisson foundation unit 20 is guided by the workers, and the engaging portions 27 are fitted into the driven steel pipe piles 21.

The caisson foundation unit 20 fitted in the steel pipe pile 21 is adjusted to a length corresponding to the shape of the seabed by the simple hydraulic jack 26.
Further, when the caisson foundation unit 20 is installed, the foundation mold 28 comes into contact with the seabed, so that an internal space 29 surrounding the caisson foundation unit 20 is formed. At this time, when a gap is generated between the foundation mold 28 and the seabed, the sandbags 30 are stacked on the outer peripheral surface of the foundation mold 28.

  Next, as shown in FIG.5 (c), the foundation concrete 31 is driven from the exclusive ship to the caisson foundation unit 20 installed in the seabed. The foundation concrete 31 is placed to such an extent that the upper surface of the internal space 29 of the caisson foundation unit 20 is filled, and solidified over time, whereby the strong caisson foundation structure 2 is formed. In addition, when the foundation concrete 31 is placed, a shear key concrete as disclosed in Patent Document 1 may be formed.

  Next, as shown in FIG. 5 (d), the caisson 1 formed on land is towed to the laying position of the offshore structure by the dedicated ship. Then, the caisson 1 is gradually lowered to the sea floor by ballast adjustment and a special ship crane, and is placed on the caisson foundation structure 2 with the upper part protruding from the sea surface.

And the filling material 13 is inject | poured in the caisson 1 from the upper surface opening part of the caisson 1, and the lid concrete 14 is laid on it. Further, secondary concrete (not shown) is placed between the caisson foundation structure 2 and the caisson 1 so that the caisson foundation structure 2 and the caisson 1 are integrated.
The marine structure can be installed on a desired seabed by the facility process as described above. In this marine structure, the caisson 1 is stably fixed by the caisson foundation structure 2, and the marine structure is laid as a structure having high water-stopping, durability, and earthquake resistance.

  In addition, the offshore structure of 1st Embodiment is not limited to embodiment mentioned above, Of course, various application implementation or deformation | transformation implementation is possible as needed. In the present embodiment, it is particularly effective to apply to a seawall or breakwater that requires high water-stopping properties, but it may also be applied to a normal seawall or breakwater, for example.

[Application example]
The caisson mount 22 of the offshore structure may be configured to assemble a metal material into a truss structure. By making the caisson mount 22 have a truss structure, the strength of the mount can be further improved and the caisson foundation unit 20 can be assembled.

[Second Embodiment]
Next, the structure of the cellular block in the offshore structure of the present invention will be described.
7A and 7B are schematic views showing the structure of the cellular block according to the second embodiment, where FIG. 7A is a front view and FIG. 7B is a top view.
The cellular block 3 of this embodiment is a structure applied when constructing a power plant similarly to 1st Embodiment. The cellular block 3 is configured to be applied to the caisson foundation structure 2 instead of the caisson 1 when the water depth from the caisson foundation structure 2 to the sea surface is shallow.
Note that in the offshore structure according to the second embodiment, the same or corresponding parts as those of the offshore structure according to the first embodiment shown above are denoted by the same reference numerals, and detailed description of the parts is as follows. Omitted.

  As shown in FIG. 7, the cellular block 3 is a block body made of concrete and extending in a straight direction. The cellular block 3 has a rectangular tube shape with an upper surface and a lower surface opened and an interior formed in a cavity.

  The cellular blocks 3 are arranged in a plurality of rows on the caisson basic structure 2 described in the first embodiment. Moreover, the cellular block 3 is formed in the dimension which becomes a little longer than the water depth from the upper surface of the caisson foundation structure 2 to the water surface in the state arrange | positioned in the caisson foundation structure 2. FIG. That is, in the state where the cellular block 3 is arranged on the caisson foundation structure 2, the cellular block 3 is in a state where the upper portion protrudes from the sea surface. Accordingly, the cellular block 3 can be easily installed by simply determining the dimensions according to the water depth and arranging the cellular blocks 3 side by side on the caisson foundation structure 2.

After the cellular block 3 is installed in the caisson foundation structure 2, the filling material 13 is injected into the cellular block 3 from the upper opening surface of the cellular block 3, and the lid concrete 14 and the upper concrete 15 are placed thereon. Is done.
As described above, the cellular block 3 installed on the caisson foundation structure 2 has the same function as the caisson 1 and can block seawater from flowing into the back surface. Thus, the marine structure can lay a revetment efficiently by properly using the caisson 1 and the cellular block 3 according to the water depth.

It is side surface sectional drawing which shows the outline of the whole structure of the offshore structure which concerns on 1st Embodiment. It is a perspective view which shows the caisson foundation structure of the offshore structure which concerns on 1st Embodiment. It is side surface sectional drawing which shows the caisson foundation structure and caisson which concern on 1st Embodiment. It is the perspective view which showed the state which inserts the caisson foundation structure which concerns on 1st Embodiment in a steel pipe pile. It is the schematic which shows the assembly process of the offshore structure which concerns on 1st Embodiment. It is the perspective view which showed the assembly process of the caisson foundation unit of the offshore structure which concerns on 1st Embodiment. It is the schematic which shows the structure of the cellular block which concerns on 2nd Embodiment, (a) is a front view, (b) is a top view. It is side surface sectional drawing which shows the structure of the caisson type offshore structure which concerns on a prior art. It is a perspective view which shows the outline of the structure structure of the caisson type offshore structure which concerns on a prior art. It is a figure which shows the structure which applied the cellular block of the caisson type offshore structure which concerns on a prior art, (a) is a front view, (b) is a top view.

Explanation of symbols

1: caisson, 2: caisson basic structure, 3: cellular block,
10: foundation rubble, 11: covering block, 12: wave-dissipating block, 13: filling material, 14: lid concrete, 15: upper concrete, 16: steel formwork, 17: lower concrete, 18: caisson installation stand, 19: Cellular block,
20: Caisson foundation unit, 21: Steel pipe pile, 22: Caisson mount, 23: Stage panel, 24: Mounting leg, 25: Side block, 26: Simple hydraulic jack, 27: Engagement part, 28: Foundation formwork, 29 : Internal space, 30: Sandbag, 31: Foundation concrete,
A: Sea side, B: Back side

Claims (5)

In a marine structure comprising a caisson laid in the ocean and a caisson foundation structure provided on the sea floor and serving as the foundation of the caisson,
The caisson foundation structure is
Multiple steel pipe piles driven into the seabed,
A caisson foundation unit that is assembled on land, fitted into the steel pipe pile and installed on the sea floor, forming a constant internal space as a concrete formwork that supports the caisson;
Foundation concrete that is placed in the internal space of the caisson foundation unit and solidified as the caisson foundation structure ,
Furthermore, the caisson foundation unit includes a caisson mount formed of a metal material, and a foundation form provided on a side surface of the caisson mount . The offshore structure according to claim 1 ,
The caisson gantry includes a stage panel in which a plurality of the metal materials are arranged side by side, a pedestal that stably supports the stage panel, a side surface of the stage panel, and a side to which the foundation formwork is attached. A marine structure characterized by including a block. The offshore structure according to claim 2 ,
The offshore structure is characterized in that the pedestal includes leg length adjusting means capable of adjusting the length to the stage panel according to the shape of the seabed. In the offshore structure according to any one of claims 1 to 3 ,
The steel pipe pile is driven in a line at a predetermined interval along the caisson laying path,
The caisson foundation unit has an engaging portion into which the steel pipe pile is fitted at a substantially central position. In the construction method of the offshore structure as described in any one of Claims 1 thru | or 4 ,
Driving the steel pipe pile into the seabed;
Assembling the caisson foundation unit on land;
Fitting the caisson foundation unit into the steel pipe pile;
Placing the foundation concrete in the internal space of the caisson foundation unit to form a caisson foundation structure;
And a step of installing a caisson on the caisson foundation structure.

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