JP7052559B2 - Suction foundation structure - Google Patents

Description

The present invention relates to a suction foundation structure including a skirt portion.

The suction foundation method is known as a type of method for constructing a foundation structure in water (see, for example, Patent Document 1). In the suction foundation method, a suction foundation structure having a top plate portion connected to an upper structure such as an offshore wind turbine and a tubular skirt portion extending downward from the top plate portion is used. .. With the tip of the skirt penetrating into the bottom ground, water is discharged from the area defined by the top plate, the skirt, and the bottom ground (hereinafter referred to as the drawing area), and a suction load is applied. And sink the suction foundation structure to a predetermined depth. After that, a filler such as grout or mortar is stuffed and injected into the drawing area. As a result, after the filler is hardened, the load of the superstructure is transmitted to the bottom ground, and the suction foundation structure is stabilized.

Japanese Unexamined Patent Publication No. 2004-339695

However, if it is premised that the filler is removed after the service period has elapsed, there is a problem that the filler cannot be stuffed and injected into the image area. That is, the suction basic structure can be removed without vibration and noise by injecting water into the drawing area using a pump and setting it in a positive pressure state. When the filler is stuffed and injected into the image area as in Patent Document 1, this removal method cannot be used.

If the filler is not stuffed into the image area, the volume of water in the image area will move uncompressed even if a large horizontal repetitive load acts on the superstructure due to waves or strong winds. It cannot be expected as a surface resistance to repeated loads. Therefore, it is necessary to increase the rooting length and horizontal resistance width of the skirt so that the repeated load does not exceed the ultimate tip bearing capacity and the ultimate peripheral frictional force, but the dimensions and structure of the skirt are large. Must be, not economical.

It should be noted that horizontal displacement occurs in the skirt portion, and negative pressure (suction pressure) acts only when the skirt is rotated and partially lifted, and the pull-out resistance force increases. However, in order for the suction pressure to function as the resistance of the foundation, horizontal displacement is allowed, which is dangerous. That is, when a repeated load acts and horizontal deformation occurs in the suction foundation structure, horizontal displacement accumulates. As a result, the performance as a foundation (friction force on the peripheral surface of the skirt portion and supporting force at the tip) deteriorates, and in the worst case, the superstructure may be tilted and collapsed.

The present invention has been made in view of such a situation, and is a suction basic structure that can be easily removed by water injection even if the filler G is interspersed and injected at the time of installation by solving the above-mentioned problems. Is to provide.

The suction foundation structure of the present invention is a suction foundation structure including a top plate portion connected to an upper structure and a skirt portion extending downward from the top plate portion, and is the top. In an installed state in which the skirt portion is sunk to a predetermined depth of the bottom ground, the lower end portion is extended downward from the lower surface of the plate portion to a length that penetrates the bottom ground, and the top plate portion, the skirt portion, and the skirt portion are extended. In the filling area drawing wall and the filling area, which divides the image area defined by the water bottom ground and defines the filling area in which the filler is stuffed and injected into the outer edge portion immediately below the top plate portion. A filled pipe that is communicated with and a water distribution pipe that is communicated with the drawing area that is not partitioned as the filling region are provided , and the filling area drawing wall is provided with the image via the water distribution pipe in the installed state. When water is injected into the formation region, a water passage that serves as a water passage from the definition region to the boundary between the filler cured in the filling region and the bottom ground is formed .
Further, in the suction foundation structure of the present invention, the water passage may be formed at a position to be buried in the bottom ground in the installed state.
Further, in the suction basic structure of the present invention, a difference bar protruding toward the filling region may be provided on the lower surface of the top plate portion .
Further , in the suction basic structure of the present invention, the skirt portion may be provided with a cylindrical outer peripheral portion, and the filling area image wall may be formed in a cylindrical shape concentric with the outer peripheral portion.

According to the present invention, even if the filler is stuffed and injected into the filling region at the time of installation, it can be easily removed by injecting water into the image area that is not partitioned as the filling region through the water pipe. Play.

It is a side sectional view which shows the structure of embodiment of the suction foundation structure which concerns on this invention. It is a side sectional view showing the state where the suction foundation structure shown in FIG. 1 is submerged to a predetermined depth of the submerged ground. It is a bottom view which shows the structure of the suction foundation structure shown in FIG. It is a figure which shows the other shape example of the filling area image wall shown in FIG. It is a figure which shows the structural example of the slit shown in FIG. It is explanatory drawing explaining the installation method of the suction foundation structure shown in FIG. It is explanatory drawing explaining the installation method of the suction foundation structure shown in FIG. It is explanatory drawing explaining the removal method of the suction foundation structure shown in FIG.

Next, an embodiment for carrying out the present invention (hereinafter, simply referred to as “embodiment”) will be specifically described with reference to the drawings.
With reference to FIGS. 1 and 2, the suction basic structure 1 of the present embodiment integrally extends downward from the top plate portion 3 connected to the superstructure 2 such as an offshore wind turbine and the top plate portion 3. It is a cup-shaped body provided with the provided skirt portion 4. The top plate portion 3 may be a bottom plate of the superstructure 2. Note that FIG. 2 shows a state in which the suction foundation structure 1 is sunk to a predetermined depth of the submerged ground (hereinafter referred to as an installation state).

The skirt portion 4 includes a tubular outer peripheral portion 41 extending downward from the outer peripheral edge of the lower end of the top plate portion 3 and a partition wall portion 42 spanning the inside of the outer peripheral portion 41. ..

In the present embodiment, as shown in FIG. 3, the top plate portion 3 has a disk shape and the outer peripheral portion 41 has a cylindrical shape. As a result, the upper portion and the outer periphery are defined by the top plate portion 3 and the outer peripheral portion 41, and a columnar imaged region A in which the lower portion is open is formed. The top plate portion 3 may be a polygon such as a rectangle. In this case, the outer peripheral portion 41 is formed in a polygonal cylindrical shape according to the shape of the top plate portion 3.

Further, in the present embodiment, as shown in FIG. 3, the partition wall portion 42 is configured in a cross shape when viewed from below. Therefore, the image area A is divided into four image area small areas a by the partition wall portion 42. The partition wall portion 42 is provided to secure the strength of the suction basic structure 1, and may be omitted if the strength is secured only by the outer peripheral portion 41. Further, the partition wall portion 42 may be used to partition the area into small image areas a of 3 or less or 5 or more.

On the lower surface of the top plate portion 3, a filling area image wall 5 is integrally extended downward. The filling area drawing wall 5 is set to a length in which _a predetermined length L1 penetrates into the bottom ground from the lower end in the installed state, and the top plate portion 3, the outer peripheral portion 41, and the bottom plate portion 3 are formed. A filling region B for filling and injecting a filler G such as grout or mortar into the outer edge immediately below is defined. The filling region B is divided into four small filling regions b by the partition wall portion 42. A filling pipe 6 communicating with each of the four small filling regions b (filling region B) in the installed state is piped to the top plate portion 3.

In the present embodiment, a cylindrical filling region image wall 5 concentric with the outer peripheral portion 41 is formed inside the outer peripheral portion 41. As a result, a uniform filling region B is formed in all directions so as to be adjacent to the inside of the outer peripheral portion 41. The filling area image wall 5 may be formed into a polygonal cylinder such as a quadrangular cylinder as shown in FIG. 4 (a) or an elliptical cylinder as shown in FIG. 4 (b).

In the installed state, the area inside the filling area image wall 5 is secured as the image area A composed of the four image area small areas a that are not partitioned as the filling area B. A water distribution pipe 7 that communicates with each of the four small image area a (image area A) in the installed state is piped to the top plate portion 3.

Referring to FIG. 5A, a slit 51 crossing the filling area drawing wall 5 is formed as a water passage at the lower end of the filling area drawing wall 5. The depth of the slit 51 is set within _a predetermined length L1 from the lower end portion. As a result, in the installed state, the slit 51 is buried in the bottom ground in the installed state, so that the filler G filled in the filling region B does not flow out to the image area A. Instead of the slit 51, as shown in FIG. 5B, a through hole 51a penetrating the filling area image wall 5 may be provided as a water passage within _a predetermined length L1 from the lower end portion.

Further, on the lower surface of the top plate portion 3, a difference bar 8 protruding toward the four small filling regions b (filling region B) is installed. The number of stirrups 8 is appropriately set according to the size of the filling region B.

Next, the installation method of the suction foundation structure 1 will be described in detail with reference to FIGS. 6 to 7.
The suction foundation structure 1 manufactured by a dock or the like is transported to the installation point by a towing ship or the like, and the skirt portion 4 is in a state where the valve 61 provided in the filling pipe 6 and the valve 71 provided in the water distribution pipe 7 are opened. The lower end of the water is grounded to the bottom of the water. As a result, as shown in FIG. 6A, the lower end portion of the skirt portion 4 penetrates into the bottom ground due to the weight of the suction foundation structure 1, and the four small image areas a (image area A) are formed. The lower part is blocked by the bottom ground with the inside filled with water. A ballast load may be applied by placing a counterweight or the like so that the lower end portion of the skirt portion 4 penetrates into the bottom ground. Further, the lower end portion of the skirt portion 4 may be penetrated into the underwater ground with all or part of the superstructure 2 connected.

Next, as shown in FIG. 6B, the valve 61 provided in the filling pipe 6 is closed (the valve 71 provided in the water distribution pipe 7 is opened), and four pumps (not shown) are used via the water distribution pipe 7. The water in the small area a (image area A) is forcibly drained. Then, a pressure difference is generated inside and outside the suction foundation structure 1 due to the forced drainage. As shown in FIG. 7A, the suction foundation structure 1 is submerged to a predetermined depth in the submerged ground by applying a suction load due to this pressure difference. In the installed state where the suction foundation structure 1 is sunk to a predetermined depth in the submerged ground, the lower end of the filled area image wall 5 penetrates into the submerged ground, and four small filled areas b (filled areas B) are defined. Will be done.

Due to the pressure difference due to the forced drainage, a negative pressure also acts on the bottom ground in the suction foundation structure 1, and an upward seepage flow is generated. Therefore, the suction foundation structure 1 is sunk while ensuring a pushing force larger than the tip resistance and the peripheral surface resistance of the suction foundation structure 1 and managing the suction load so that the bottom ground is not destroyed by the infiltration flow.

Next, the valve 71 provided in the water distribution pipe 7 is closed, the valve 61 provided in the filling pipe 6 is opened, and the filling material G is filled in the four filling small regions b (filling region B) from the filling pipe 6. inject.

After the filler G is cured, as shown in FIG. 7B, even if a large horizontal load is applied by wave power or wind power, in addition to the resistance and the passive resistance due to the tip support of the suction foundation structure 1. The cured filler G is surface-supported and resists. Therefore, the cumulative displacement due to the repeated load can be significantly reduced. Furthermore, it greatly contributes to the suppression of tilting and falling due to large-scale earthquakes.

Further, by hardening the filler G, a solidified body integrated with the suction basic structure 1 is constructed on the outer edge portion just below the top plate portion 3 by a difference streak 8 or the like, and the corner portion of the suction basic structure 1 is formed. Reinforced. As a result, the degree of stress acting on the outer peripheral portion 41 of the top plate portion 3 is also reduced. Not only the reduction but also the miniaturization of the crane vessel makes it economical. Further, it is economical because the filler G is placed only in a part of the drawing area A instead of the entire area.

Next, the removal method of the suction foundation structure 1 will be described in detail with reference to FIG.
After the service period has elapsed, as shown in FIG. 8, the valve 71 provided in the water distribution pipe 7 is opened, and a pump (not shown) is used in the four small image areas a (image area A) via the water pipe 7. Water is injected to generate a positive pressure in the image area A inside the filling area image wall 5, and the suction foundation structure 1 is removed.

When a positive pressure is generated in the image area A inside the filling area image wall 5, the slit 51 provided in the filling area image wall 5 becomes a water path, and the four small filling areas b (filling area b) are formed. Water flows into the boundary between the filler G solidified in B) and the bottom of the water. As a result, positive pressure due to water injection can be applied to the entire cross-sectional area of the suction foundation structure 1. Therefore, even if the same water injection equipment as the conventional one is used, the suction basic structure 1 can be removed without vibration and noise. Since the cured filler G is integrated with the suction basic structure 1 by the difference bar 8, it is removed together with the suction basic structure 1.

In the present embodiment, the water distribution pipe 7 is configured to perform drainage at the time of installation and water injection at the time of removal, but the drainage pipe and the water injection pipe may be provided separately.

As described above, the present embodiment is a suction basic structure 1 including a top plate portion 3 connected to the superstructure 2 and a skirt portion 4 extending downward from the top plate portion 3. In the installed state where the skirt portion 4 is sunk to a predetermined depth of the bottom ground, the lower end portion is extended downward from the lower surface of the top plate portion 3 so as to penetrate into the bottom ground, and the top plate portion 3 is provided. , The image area A defined by the skirt portion 4 and the water bottom ground is partitioned, and the filling area B is defined by filling and injecting the filler G into the outer edge portion immediately below the top plate portion 3. It includes a wall 5, a filling pipe 6 communicated with a filling region B, and a water distribution pipe 7 communicated with a drawing area A not partitioned as a filling region B.
With this configuration, even if the filler G is intercalated and injected into the filling region B at the time of installation, it can be easily removed by injecting water into the image area A which is not partitioned as the filling region B through the water distribution pipe 7. ..

Further, in the present embodiment, a difference bar 8 projecting toward the filling region B is installed on the lower surface of the top plate portion 3.
With this configuration, the cured filler G is integrated with the suction basic structure 1, so that the cured filler G can be removed together with the suction basic structure 1.

Further, in the present embodiment, when water is injected into the image area A through the water distribution pipe 7 in the filling area image wall 5 in the installed state, the filler G cured in the filling area B from the image area A and the water bottom A slit 51, which serves as a water channel to the boundary with the ground, is formed as a water passage.
With this configuration, positive pressure due to water injection can be applied to the entire cross-sectional area of the suction foundation structure 1. Therefore, the suction basic structure 1 can be removed without vibration and noise even if the same water injection equipment as the conventional one is used.

Further, in the present embodiment, the slit 51 formed as a water passage is formed at a position to be buried in the bottom ground in the installed state.
With this configuration, the filler G filled in the filling region B does not flow out into the image area A.

Further, in the present embodiment, the skirt portion 4 includes a cylindrical outer peripheral portion 41, and the filling area image wall 5 is formed in a cylindrical shape concentric with the outer peripheral portion 41.
With this configuration, the filling region B that is adjacent to the inside of the outer peripheral portion 41 and is uniform in all directions is formed. By filling and injecting the filler G into the filling region B, it is possible to uniformly resist the repeated load in the horizontal direction in all directions.

The present invention has been described above based on the embodiments. It is understood by those skilled in the art that this embodiment is an example, and that various modifications are possible in the combination of each of these components, and that such modifications are also within the scope of the present invention.

1 Suction foundation structure 2 Upper structure 3 Top plate part 4 Skirt part 5 Filling area painting wall 6 Filling pipe 7 Water distribution pipe 8 Difference bar 41 Outer peripheral part 42 Barrier part 51 Slit 51a Through hole 61 Valve 71 Valve A painting area B Filling area G Filling material a Imaging small area b Filling small area

Claims (4)

A suction foundation structure including a top plate portion connected to the superstructure and a skirt portion extending downward from the top plate portion.
In an installed state in which the skirt portion is sunk to a predetermined depth of the bottom ground, the lower end portion is extended downward from the lower surface of the top plate portion so as to penetrate the bottom ground, and the top plate portion and the skirt are extended. A filling area drawing wall that divides the drawing area defined by the portion and the underwater ground and defines a filling area in which the filler is stuffed and injected into the outer edge portion directly below the top plate portion.
A filling pipe communicating with the filling region and
It is provided with a water pipe that communicates with the definition area that is not partitioned as the filling area.
When water is injected into the drawing area through the water distribution pipe in the installed state, the filling area drawing wall reaches the boundary between the filling material cured in the filling area and the water bottom ground from the drawing area. A suction basic structure characterized by the formation of a water channel that serves as a water channel . The suction basic structure according to claim 1 , wherein the water passage is formed at a position to be buried in the bottom ground in the installed state. The suction basic structure according to claim 1 or 2 , wherein a difference bar protruding toward the filling region is provided on the lower surface of the top plate portion. The skirt portion has a cylindrical outer peripheral portion and has a cylindrical outer peripheral portion.
The suction basic structure according to any one of claims 1 to 3, wherein the filling area image wall is formed in a cylindrical shape concentric with the outer peripheral portion.

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