JP7163661B2 - Suction base structure - Google Patents

Description

The present invention relates to a suction substructure with a skirt.

A suction foundation construction method is known as one type of construction method for constructing a foundation structure in water (see, for example, Patent Document 1). The suction foundation construction method uses a suction foundation structure that includes a top slab that is connected to an upper structure such as an offshore wind turbine, and a tubular skirt portion that extends integrally downward from the top slab. . With the tip of the skirt penetrating into the seabed ground, water is discharged from the area defined by the top slab, the skirt and the seabed ground (hereinafter referred to as the defined area), and a suction load is applied. and sink the suction foundation structure to a predetermined depth. Thereafter, a filling material such as grout or mortar is injected into the defined area. As a result, after the filler hardens, the load of the superstructure is transmitted to the submerged ground, and the suction foundation structure is stabilized.

JP-A-2004-339695

However, if it is assumed that the structure will be removed after the service period has passed, there is a problem that the filling material cannot be injected into the defined region. That is, the suction substructure can be removed without vibration and noise by injecting water into the defined area using a pump to create a positive pressure state. In the case where the filling material is injected into the defined region as in Patent Document 1, this removing method cannot be used.

If the filling material is not injected into the defined area, even if a large cyclic load acts horizontally on the upper structure due to waves or strong winds, the volume of water in the defined area moves without being compressed. Therefore, it cannot be expected as surface resistance against repeated loads. Therefore, it is necessary to increase the penetration length and horizontal resistance width of the skirt so that the repeated load does not exceed the ultimate end support force and ultimate peripheral friction force. and it is not economical.

It should be noted that a horizontal displacement occurs in the skirt portion, and only when it rotates and is partly lifted does negative pressure (suction pressure) act and pull-out resistance increases. However, in order for the suction pressure to function as the resistance force of the foundation, horizontal displacement is allowed, which is dangerous. That is, when a repetitive load acts and horizontal deformation occurs in the suction substructure, the horizontal displacement is accumulated. As a result, the performance of the foundation (peripheral friction force of the skirt portion and tip support force) is degraded, and in the worst case, there is a risk that the upper structure will tilt and collapse.

The present invention has been made in view of such circumstances, and provides a suction foundation structure that solves the above-mentioned problems and can be easily removed by pouring water even if the filling material is injected at the time of installation. to provide.

A suction foundation structure according to the present invention includes a top slab connected to an upper structure and a skirt extending downward from the top slab. After defining a defined area with the ground, the suction foundation structure is installed by sinking the tip of the entire skirt portion to a predetermined depth of the water bottom ground, for forcibly draining water from the defined area. an installation drainage pipe, a filling pipe for filling and injecting a filler into the defined area after water is forcibly drained through the installation drainage pipe, and downward from the lower surface of the top plate portion a removal water injection pipe for injecting water into the lower part of the filling material that protrudes and is filled and hardened, and a plurality of water injection holes are formed in the peripheral surface of the removal water injection pipe, and the water injection The hole is provided with an anti-clogging member having a function of preventing sediment from entering the pipe while ensuring water permeability from the inside to the outside of the pipe.
Furthermore, in the suction basic structure of the present invention, the clogging prevention member may be a drain material that covers the water injection hole from the inside.
Furthermore, in the suction substructure of the present invention,
The clogging prevention member may be a valve member that covers the water injection hole from the outside, is fixed at the lower end located on the tip side of the removal water injection pipe, and is attached so that the upper end side opens.
Furthermore, in the suction substructure of the present invention,
A collar portion may be provided on a peripheral surface of a predetermined length from the tip of the withdrawal water injection pipe.
Furthermore, in the suction basic structure of the present invention, the water injection pipe for removal may have a closed structure with a sharp tip.
Furthermore, in the suction foundation structure of the present invention, a lower surface of the top slab may be provided with a connecting bar projecting downward.
Furthermore, in the suction foundation structure of the present invention, the installation drainage pipe and the removal water injection pipe may be integrated as a double pipe.

According to the present invention, even if the filling material is filled in during installation, the water injection pressure can be applied between the filling material and the bottom of the water by injecting water from the water injection pipe 6 for removal, and the suction foundation can be easily performed. The effect is that the structure can be removed.

1 is a side sectional view showing the configuration of an embodiment of a suction substructure according to the present invention; FIG. FIG. 2 is a side cross-sectional view showing a state in which the suction foundation structure shown in FIG. 1 is sunk to a predetermined depth in the submerged ground; FIG. 2 is a bottom view showing the configuration of the suction substructure shown in FIG. 1; It is a figure which shows the structure of the water injection pipe for removal shown in FIG. 5 is a diagram showing a configuration example of the anti-clogging member shown in FIG. 4; FIG. FIG. 2 is an explanatory diagram illustrating an installation method of the suction foundation structure shown in FIG. 1; FIG. 2 is an explanatory diagram illustrating an installation method of the suction foundation structure shown in FIG. 1; It is explanatory drawing explaining the removal construction method of the suction foundation structure shown in FIG. 1. It is a figure which shows the structural example of the double pipe which put together the drainage pipe for installation shown in FIG. 1, and the water injection pipe for removal.

Next, modes for carrying out the present invention (hereinafter simply referred to as "embodiments") will be specifically described with reference to the drawings.
Referring to FIGS. 1 and 2, the suction foundation structure 1 of the present embodiment includes a top slab 3 connected to an upper structure 2 such as an offshore wind turbine, and a top slab 3 extending integrally downward from the top slab 3. It is a cup-shaped body with a skirt portion 4 provided. The top slab 3 may be the bottom slab of the upper structure 2 . FIG. 2 shows a state in which the suction foundation structure 1 is sunk to a predetermined depth in the ground (hereinafter referred to as "installed state"). In the installed state, a filling material G (for example, concrete, grout, or mortar) is injected into the lower portion of the top slab 3 . Then, the hardened filler G functions as part of the suction substructure 1 .

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

In this embodiment, as shown in FIG. 3, the top plate portion 3 is disk-shaped, and the outer peripheral portion 41 is cylindrical. As a result, a columnar defined area A is formed in which the upper part and the outer circumference are defined by the top plate part 3 and the outer circumference part 41, and the lower part is open. The top plate portion 3 may be polygonal such as rectangular. In this case, the outer peripheral portion 41 is formed in a polygonal tubular shape corresponding to the shape of the top plate portion 3 .

In addition, in the present embodiment, as shown in FIG. 3, the partition wall 42 is configured in a cross shape when viewed from below. Therefore, the defined area A is partitioned into four defined small areas a by the partition walls 42 . The partition wall 42 is provided to ensure the strength of the suction base structure 1, and may be omitted if the strength is ensured only by the outer peripheral portion 41. FIG. In addition, partition walls 42 may be used to partition into 3 or less or 5 or more defined subregions a.

The top plate 3 is provided with an installation drain pipe 5, a removal water injection pipe 6, a filling pipe 7, and a drain pipe 8, which communicate with the four defined subregions a (defined region A) respectively.

The installation drainage pipe 5 is a pipe for forcibly draining the water in the four defined small areas a (defined area A). The installation drainage pipe 5 is arranged in four small defined areas a (defined area A) from the lower surface side of the top plate 3 so as to communicate with the four small defined areas a (defined area A) even in the installed state shown in FIG. (Defined area A) is opened respectively.

The removal water injection pipe 6 protrudes from the lower surface of the top plate 3, and in the installed state shown in FIG.

Referring to FIG. 4, the removal water injection pipe 6 has a closed tip with a sharp tip, and is set to a length that allows _a predetermined length L1 from the tip to penetrate into the waterbed ground in the installed state. A plurality of slit-shaped water injection holes 61 extending in the axial direction of the removal water injection pipe 6 are formed within _a predetermined length L1 from the tip of the removal water injection pipe 6, and a predetermined length L from the tip. A collar portion 63 is provided on the peripheral surface of ₁ . Therefore, in the installed state, the water injection hole 61 of the removal water injection pipe 6 is positioned in the water bottom ground, and the flange 63 abuts on the water bottom.

The water injection hole 61 is provided with a clogging preventing member 62 for preventing clogging. The anti-clogging member 62 has a function of preventing sediment from entering the pipe while ensuring water permeability from the inside to the outside of the pipe.

As the anti-clogging member 62, for example, a drain material 62a can be used as shown in FIG. 5(a). FIG. 5(a) shows an example in which the clogging prevention member 62 has a double-sandwich structure in which two drain members 62a are sandwiched between wire meshes X, and the water injection hole 61 is covered from the inside. ing.

Also, as shown in FIG. 5B, the drain material 62a may fill the entire inside of the pipe where the water injection hole 61 is formed.

As the anti-clogging member 62, for example, as shown in FIG. 5(c), a valve member 62b attached so as to cover the water injection hole 61 from the outside can be used. The valve member 62b is attached so that the lower end located on the tip side of the withdrawal water injection pipe 6 is fixed, and the upper end side opens as shown by the dotted line in FIG. 5(c).

The filling pipe 7 is a pipe for filling and injecting the filler G into the four defined subregions a (defined region A) in the installed state shown in FIG. The filling pipe 7 is arranged in four defined small areas a (defined area A) from the lower surface side of the top plate 3 so as to communicate with the four defined small areas a (defined area A) even in the installed state shown in FIG. It is opened in each of the forming regions A).

The water drain pipe 8 is a pipe for discharging the water filled in the four defined subregions a (defined region A) to the outside of the body when filling the filler G with filling. The drain pipe 8 penetrates the top plate portion 3 and communicates the four defined small areas a (defined area A) with the outside of the body. Note that the drain pipe 8 may be laid on the outer peripheral portion 41 .

In addition, on the lower surface of the top plate portion 3, intervening bars 9 projecting toward the four defined small areas a (defined area A) are installed. The number of the connecting lines 9 is appropriately set according to the size of the defined area A. As shown in FIG.

Next, a method for installing the suction foundation structure 1 will be described in detail with reference to FIGS. 6 and 7. FIG.
A suction foundation structure 1 manufactured at a dock or the like is transported to an installation point by a tow ship or the like. A valve 50 provided on the installation drain pipe 5, a valve 60 provided on the removal water injection pipe 6, a valve 70 provided on the filling pipe 7, and a valve 80 provided on the drain pipe 8. is opened, the lower end of the skirt part 4 is grounded on the bottom of the water. In addition, since the valve 80 is to be opened and closed underwater, it is preferable to configure it with a remotely operable electromagnetic valve.

As a result, as shown in FIG. 6(a), the lower end of the skirt portion 4 penetrates into the waterbed ground due to the weight of the suction foundation structure 1, and the four defined subregions a (defined region A) are The lower part is blocked by the submerged ground while the inside is filled with water. A ballast load may be applied by placing a counterweight or the like to cause the lower end of the skirt portion 4 to penetrate into the waterbed ground. Alternatively, the lower end of the skirt portion 4 may be penetrated into the waterbed ground while all or part of the upper structure 2 is connected.

Next, as shown in FIG. 6(b), the valve 60 provided on the removal water injection pipe 6, the valve 70 provided on the filling pipe 7, and the valve 80 provided on the drain pipe 8 are closed. (The valve 50 provided in the installation drainage pipe 5 is opened), and the water in the four defined small regions a (defined region A) is forcibly drained through the installation drainage pipe 5 by a pump (not shown). Then, a pressure difference is generated between the inside and outside of the suction base structure 1 due to forced drainage. A suction load associated with this pressure difference is applied, and as shown in FIG.

In the installation state where the suction foundation structure 1 is sunk to a predetermined depth in the waterbed ground, the tip of the removal water injection pipe 6 penetrates the waterbed ground, and the water injection hole 61 of the removal water injection pipe 6 is positioned in the waterbed ground. , the flange 63 comes into contact with the bottom of the water.

Due to the pressure difference caused by the forced drainage, a negative pressure also acts on the submerged ground in the suction foundation structure 1, generating an upward seepage flow. Therefore, the suction foundation structure 1 is submerged while securing a pushing force greater than the tip resistance and peripheral surface resistance of the suction foundation structure 1 and controlling the suction load so that the submerged ground will not be destroyed by the seepage flow.

Next, the valve 50 provided on the installation drain pipe 5 is closed, and the valve 70 provided on the filling pipe 7 and the valve 80 provided on the drain pipe 8 are opened (provided on the water injection pipe 6 for removal). The closed valve 60 is closed), and the filling material G is injected from the filling pipe 7 into the four defined subregions a (defined region A).

A collar portion 63 is attached to the outer periphery of the withdrawal water injection pipe 6 so as to contact the bottom of the water in the installed state. Therefore, when filling the filling material G, the collar part 63 prevents the filling material G from entering between the outer periphery of the removal water injection pipe 6 and the water bottom ground. As a result, it is possible to prevent the filling material G from reaching the water injection hole 61 along the outer circumference of the removal water injection pipe 6 and blocking the water injection hole 61 .

After curing the filler G, as shown in FIG. 7(b), even if a large repetitive load acts in the horizontal direction due to wave force or wind force, in addition to the resistance and passive resistance due to the tip support of the suction foundation structure 1, As a result, the hardened filler G provides surface support and resistance. Therefore, the accumulated displacement due to repeated load can be greatly reduced. Furthermore, it greatly contributes to the suppression of tilting and overturning due to large-scale earthquakes.

In addition, due to the hardening of the filler material G, a solidified body integrated with the suction base structure 1 by the interposition bars 9 or the like is constructed as a part of the suction base structure 1 immediately below the top plate portion 3. 1 is reinforced. As a result, the degree of stress acting on the outer peripheral portion 41 of the top plate portion 3 is also reduced. It is economical not only because of the reduction but also because of the miniaturization of the hoist ship.

Next, a method for removing the suction foundation structure 1 will be described in detail with reference to FIG.
When the in-service period has passed, as shown in FIG. Water is poured into the lower portion of the defined small area a (defined area A).

The water discharged from the water injection hole 61 of the removal water injection pipe 6 enters between the filler G integrated with the suction base structure 1 and the bottom of the water just below the top plate 3 . As a result, water injection pressure can be applied to the inner cross-sectional area of the suction base structure 1, and the suction base structure 1 can be easily removed. Therefore, even if the same water injection equipment as the conventional one is used, the suction foundation structure 1 can be removed without vibration and noise. Since the hardened filler G is integrated with the suction base structure 1 by the intervening bars 9, it is removed together with the suction base structure 1. As shown in FIG.

In this embodiment, the installation drainage pipe 5 and the removal water injection pipe 6 are provided separately, but as shown in FIG. You may make it put together as one as the double pipe 10. FIG. In addition, FIG. 9 has shown the installation state.

The double pipe 10 includes an installation drainage pipe 5 and a withdrawal water injection pipe 6 arranged inside the installation drainage pipe 5 . The double pipe 10 protrudes from the lower surface of the top plate portion 3, and in the installed state, the protruding tip penetrates the waterbed ground, the water injection hole 61 of the water injection pipe for removal 6 is located in the waterbed ground, and the flange 63 abuts the bottom. Also, in the installed state, a plurality of drainage holes 51 of the installation drainage pipe 5 are formed on the outer periphery of the double pipe 10 located in the four defined small areas a (defined area A).

In the present embodiment, the installation drainage pipe 5 and the filling pipe 7 are provided separately, but the installation drainage pipe 5 and the filling pipe 7 may be used together.

As described above, in this embodiment, the suction base structure 1 includes the top plate portion 3 connected to the upper structure 2 and the skirt portion 4 extending downward from the top plate portion 3. In an installation state in which the installation drain pipe 5 communicated with the defined area A defined by the top slab 3, the skirt 4, and the waterbed ground, and the skirt 4 are sunk to a predetermined depth in the waterbed ground. , a filling pipe 7 for intermittently injecting the filling material G into the demarcated area A, and a water injection pipe for removal projecting downward from the lower surface of the top plate 3 with a length that the tip penetrates into the waterbed ground in the installed state. 6, and a plurality of water injection holes 61 are formed on the peripheral surface of the removal water injection pipe 6 that penetrates into the waterbed ground in the installed state, and the water injection holes 61 ensure water permeability from the inside of the pipe to the outside of the pipe. A clogging preventive member 62 is provided that has a function of preventing sediment from entering the pipe in this state.
With this configuration, even if the filling material G is filled in during installation, the water injection pressure can be applied between the filling material G and the bottom of the water by injecting water from the water injection pipe 6 for removal, and the suction foundation can be easily performed. Structure 1 can be removed. Moreover, clogging of the water injection hole 61 can be prevented.

Furthermore, in this embodiment, the clogging prevention member 62 is a drain member 62a that covers the water injection hole 61 from the inside.
With this configuration, it is possible to prevent sediment from entering the pipe while ensuring water permeability from the inside to the outside of the pipe with a simple structure.

Furthermore, in the present embodiment, the clogging prevention member 62 is a valve member that covers the water injection hole 61 from the outside, is fixed at the lower end located on the tip side of the withdrawal water injection pipe 6, and is attached so that the upper end side opens. 62b.
With this configuration, it is possible to prevent sediment from entering the pipe while ensuring water permeability from the inside to the outside of the pipe with a simple structure. Also, the water discharged from the water injection hole 61 is guided toward the lower surface of the filler G by the valve member 62b. Therefore, water can enter between the filler G and the bottom of the water with a relatively low water injection pressure.

Furthermore, in the present embodiment, the peripheral surface of the withdrawal water injection pipe 6 is provided with a flange portion 63 that abuts on the bottom of the water in the installed state.
With this configuration, it is possible to prevent the filling material G from reaching the water injection hole 61 along the outer circumference of the removal water injection pipe 6 and blocking the water injection hole 61 . In addition, the flange portion 63 may not be used in ground with low water permeability such as cohesive ground.

Furthermore, in the present embodiment, the withdrawal water injection pipe 6 has a closed structure with a sharp tip.
This configuration facilitates the penetration of the removal water injection pipe 6 into the waterbed ground, and the water injection hole 61 is formed so that the tip portion can be reliably positioned in the waterbed ground.

Furthermore, in the present embodiment, a lower surface of the top plate portion 3 is provided with a connecting bar 9 projecting downward.
With this configuration, the hardened filler G is integrated with the suction base structure 1 , so that the hardened filler G can be removed together with the suction base structure 1 .

Furthermore, in this embodiment, the installation drainage pipe 5 and the removal water injection pipe 6 are integrated as a double pipe 10 .
With this configuration, the installation drainage pipe 5 and the removal water injection pipe 6 can be easily laid on the top plate portion 3 .

The present invention has been described above based on the embodiments. It should be understood by those skilled in the art that this embodiment is an example, and that various modifications can be made to the combination of each component, etc., and that such modifications are also within the scope of the present invention.

1 Suction base structure 2 Upper structure 3 Top slab 4 Skirt 5 Drainage pipe for installation 6 Water injection for removal 7 Filling pipe 8 Drainage pipe 9 Insertion bar 10 Double pipe 41 Periphery 42 Partition wall 50 Valve 51 Drain hole 60 Valve 61 Water injection hole 62 Clogging prevention member 62a Drain material 62b Valve member 63 Flange 70 Valve 80 Valve A Defined region G Filler X Wire mesh a Defined small region

Claims (7)

It comprises a top slab connected to an upper structure and a skirt portion extending downward from the top slab.After defining a defined area by the top slab portion, the skirt portion, and the seabed ground, the tip of the entire skirt portion is sunk to a predetermined depth in the seabed ground and installed.A suction substructure,
for forcibly draining water from said defined area an installation drain pipe;
After water is forcibly drained through the installation drain pipe a filling pipe for filling and injecting a filling material into the defined region;
downward from the bottom surface of the top platehandoverhang, for pouring water into the lower part of the filling material that has been hardened by fillingEquipped with a water injection pipe for removal,
A plurality of water injection holes are formed on the peripheral surface of the removal water injection pipe, and the water injection holes have a function of preventing sediment from entering the pipe while ensuring water permeability from the inside of the pipe to the outside of the pipe. A suction base structure, characterized in that it is provided with an anti-clogging member comprising: 2. The suction substructure according to claim 1, wherein the clogging prevention member is a drain material covering the water injection hole from the inside. The clogging prevention member is a valve member that covers the water injection hole from the outside, is fixed at a lower end located on the tip side of the removal water injection pipe, and is attached so that the upper end side opens. 2. A suction substructure according to claim 1. 4. The suction foundation structure according to claim 1, wherein a flange is provided on a circumferential surface of a predetermined length from the tip of said removal water injection pipe. 5. The suction basic structure according to claim 1, wherein the water injection pipe for withdrawal has a closed structure with a sharp tip. The suction substructure according to any one of claims 1 to 5, wherein a lower surface of the top slab is provided with a connecting bar projecting downward. 7. The suction foundation structure according to any one of claims 1 to 6, wherein the installation drainage pipe and the removal water injection pipe are integrated as a double pipe.

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