JP7122265B2 - FOUNDATION STRUCTURE FOR OFFSHORE WIND POWER GENERATION AND CONSTRUCTION METHOD OF FOUNDATION STRUCTURE FOR OFFSHORE WIND POWER GENERATION - Google Patents

Description

The present invention relates to a foundation structure for offshore wind power generation and a construction method for the foundation structure for offshore wind power generation.

The foundation types of offshore wind turbines include monopile foundations, pile foundations, and gravity foundations. A gravity foundation is effective when installing an offshore wind turbine in the open ocean where the seabed ground is hard. When installing an offshore wind turbine in a relatively shallow sea area, a footing pile foundation is installed on the seabed, and piles are driven into the seabed using various machines from a work table on the work stage provided on the top of the footing. There is also a basic structure in which the head is fixed to a footing (see, for example, Patent Document 1).

Japanese Patent No. 4696854

However, in the foundation type using piles as in the method described in Patent Document 1, it takes time to drive the piles, especially when the seabed ground is bedrock, and it is assumed that the bedrock will crack when the piles are driven. You may not get the support. However, since offshore wind turbines have become larger in recent years, it is not easy to construct a gravity foundation that does not involve pile driving.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its object is to provide a foundation structure for offshore wind power generation that can reduce the construction period and construction costs by significantly miniaturizing the gravity foundation installed on the seabed. and to provide a construction method for the foundation structure for offshore wind power generation.

In order to achieve the above-mentioned object, the first invention is a foundation structure for offshore wind power generation, which comprises a direct foundation made of concrete installed on the seabed, and a wind turbine tower integrated with the direct foundation and installed on the top. a concrete tower that is filled with a first filling material inside the concrete tower, and the spread foundation and the concrete tower are held against the seabed ground by a ground anchor that penetrates the inside of the concrete tower one end of the ground anchor is anchored to the seabed ground, and the other end of the ground anchor is anchored to an anchoring portion formed on the sea portion of the concrete tower. Structure.

In the first invention, since the spread foundation and the concrete tower are made of concrete and integrated, the manufacturing cost of the concrete tower can be reduced compared to the case where the concrete tower is made of steel, and the stress transmission from the concrete tower can be reduced. Reinforcement of the spread foundation can be minimized. In addition, since the inside of the concrete tower is filled with filling material, the total weight of the foundation structure for offshore wind power generation can be secured even if the spread foundation installed on the seabed is greatly reduced in size, and stability against overturning due to wave power etc. can be secured. can be maintained.

If a spread foundation and a ground anchor are used together, a vertical force can be introduced by the ground anchor and the stability against overturning due to wave force or the like can be improved, so the spread foundation installed on the seabed can be downsized. Further, if the other end of the ground anchor is fixed to the fixing portion formed in the sea portion of the lower structure, diver work in water is not required when constructing the ground anchor.

The fixing part is fixed inside the concrete tower, for example, above the first filling material. Further, it is preferable that a sheath pipe is embedded in the spread foundation, and the ground anchor penetrates the sheath pipe and is fixed to the seabed ground.
If the fixing part is provided on the upper part of the filling material, the degree of freedom in the timing of construction of the ground anchor increases. By embedding the sheath pipe, the ground anchor can be easily penetrated directly into the foundation.

The spread foundation may have a cavity, and the cavity may be filled with a second filling material.
If the second stuffing material is filled, the total weight during towing can be reduced, and the total weight during use can be increased to improve stability against overturning due to wave force or the like.

A second invention is a method for constructing a foundation structure for offshore wind power generation, comprising a step a of integrally manufacturing a spread foundation and a concrete tower on which a wind turbine tower is to be installed on land using concrete; A step b of towing the spread foundation and the concrete tower to a site and sinking them on the seabed; a step c of filling the inside of the concrete tower with a first filling material; is fixed to the seabed ground by a ground anchor that penetrates the inside of the concrete tower, and in the step d, one end of the ground anchor is fixed to the seabed ground, and the ground anchor The construction method for the foundation structure for offshore wind power generation is characterized in that the other end is fixed to a fixing portion formed in the sea portion of the concrete tower .

In the second invention, since the spread foundation and the concrete tower are made of concrete and integrated on land, the manufacturing cost of the concrete tower is reduced compared to the case where the concrete tower is made of steel, and the stress from the concrete tower is reduced. Minimize reinforcement of direct foundation for transmission. Also, work at sea can be minimized. Furthermore, since the inside of the concrete tower is towed while it is hollow, the total weight of the integrated structure of the spread foundation and the concrete tower can be reduced, and the applicability to crane ships and the like can be enhanced. In addition, since the inside of the concrete tower is filled with filling material after sinking, the total weight of the foundation structure for offshore wind power generation can be secured even if the spread foundation installed on the seabed is greatly reduced in size, and it is possible to reduce the influence of wave power during operation. It becomes possible to maintain stability against overturning.

If a spread foundation and a ground anchor are used together, a vertical force can be introduced by the ground anchor and the stability against overturning due to wave force or the like can be improved, so the spread foundation installed on the seabed can be downsized. Further, if the other end of the ground anchor is fixed to the fixing portion formed in the sea portion of the lower structure, diver work in water is not required when constructing the ground anchor.

The anchoring part is fixed inside the concrete tower, for example, on top of the first filling material. Further, it is preferable that a sheath pipe is embedded in the spread foundation, and the ground anchor is inserted into the sheath pipe and fixed to the seabed ground in the step d.
If the fixing part is provided on the upper part of the filling material, the degree of freedom in the timing of construction of the ground anchor increases. In addition, by embedding the sheath pipe, the ground anchor can be easily penetrated directly into the foundation.

The spread foundation may have a cavity, and the cavity may be filled with a second filling material in step c.
If the second filling material is filled in step c, the total weight during towing in step a can be reduced, and the total weight during service can be increased to improve stability against overturning due to wave force or the like. .

According to the present invention, it is possible to provide a foundation structure for offshore wind power generation and a construction method for a foundation structure for offshore wind power generation, which can greatly reduce the size of the gravity foundation installed on the seabed and reduce the construction period and construction cost.

The figure which shows the process which integrates the direct foundation 3 and the concrete tower 7, and manufactures the gravity type foundation 4. FIG. The figure which shows the process of towing the gravity type foundation 4. FIG. The figure which shows the process of sinking the gravity type foundation 4. FIG. FIG. 4 is a diagram showing a step of driving a ground anchor 31; FIG. 4 is a diagram showing a process of filling filling sands 37-1 and 37-2; FIG. 4 is a diagram showing a process of installing a tower 41 on a concrete tower 7; The figure which shows the basic structure 39a. The figure which shows the basic structure 39b. The figure which shows the basic structure 39c.

A first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing a process of manufacturing a gravity foundation 4 by integrating a direct foundation 3 and a concrete tower 7. As shown in FIG. FIG. 1(a) is a vertical sectional view, and FIG. 1(b) is a top view. FIG. 1(a) is a cross-sectional view along the arrow AA shown in FIG. 1(b).

In the process shown in FIG. 1, a gravity type foundation 4 in which the direct foundation 3 and the concrete tower 7 are integrated is manufactured in the land yard 1 . The spread foundation 3 is a member made of RC (reinforced concrete). The concrete tower 7 is a member made of PC (prestressed concrete). The spread foundation 3 and the concrete tower 7 can be made of lightweight concrete, high-strength concrete or ultra-high-strength fiber reinforced concrete (UFC) to reduce the member thickness, in addition to ordinary concrete. You may try to reduce the weight.

The spread foundation 3 has a cavity 5 . A sheath pipe 11 is embedded in the direct foundation 3 to penetrate the bottom surface. The lower end of the sheath tube 11 is closed with a lid 13 .

A fixing plate 15 is provided on the upper part of the concrete tower 7 . The fixing plate 15 has a guide hole 17 and a filling hole 19 . The guide hole 17 is provided at a position corresponding to the ground anchor 31 (see FIG. 4 and the like) in plan view. The guide holes 17 are provided, for example, on two concentric circles. The filling hole 19 is desirably provided so as not to connect with the guide hole 17 . The fixing plate 15 may be made of concrete and integrated with the concrete tower 7, or may be made of steel and fixed to the concrete tower 7 with a bracket (not shown).

The gravity foundation 4 is moved from the land yard 1 to the quay using, for example, moving means 14 .

FIG. 2 is a diagram showing the process of towing the gravity foundation 4. As shown in FIG. FIG. 2(a) is a vertical sectional view, and FIG. 2(b) is a view from above. In the process shown in FIG. 2, the gravity foundation 4, in which the direct foundation 3 and the concrete tower 7 are integrated, is floated on the sea surface 21, connected with a towing wire 24, and towed by a ship (not shown) to be transported to the site. During towing, a temporary floating body 23 is attached around the direct foundation 3 as required.

FIG. 3 is a diagram showing the process of sinking the gravity foundation 4. As shown in FIG. In the process shown in FIG. 3, the inside 9 of the concrete tower 7 is filled with water, and the gravity foundation 4 in which the direct foundation 3 and the concrete tower 7 are integrated is sunk on the bedrock 22 on the seabed. The lid 13 of the sheath tube 11 is removed at an appropriate time.

FIG. 4 is a diagram showing a step of driving the ground anchor 31. As shown in FIG. FIG. 4(a) is a vertical cross-sectional view showing the entire gravity foundation 4, and FIG. 4(b) is an enlarged view of the vicinity of the anchor bodies 33 in a portion where a plurality of anchor bodies 33 are arranged close to each other. .

In the process shown in FIG. 4 , a work deck 25 is installed on the sea portion of the concrete tower 7 , and a crawler drill 27 on the deck 25 drills the bedrock 22 while protecting the hole wall with a casing pipe 29 . Then, the ground anchor 31 is driven, and the lower end of the ground anchor 31 is fixed to the bedrock 22 by the anchor body 33 . At this time, the guide hole 17 and the sheath tube 11 are used as guides for the casing pipe 29 . The upper end of the ground anchor 31 is fixed to the fixing plate 15 by the fixing tool 35 . Thus, the gravity foundation 4 is fixed to the bedrock 22 of the seabed by ground anchors 31 penetrating the interior 9 of the concrete tower 7 .

In the process shown in FIG. 4, as described above, the ground anchor 31 is driven using the guide hole 17 shown in FIG. 1(b) as a guide. If the ground anchors 31-2 are close to each other, it is desirable to form the anchor bodies 33-1 and 33-2 at different depths as shown in FIG. 4(b). If the outer and inner ground anchors 31 are sufficiently separated, the anchor bodies 33 may be formed to the same depth.

The reaction force of the ground anchor 31 on the fixture 35 side is transmitted to the concrete tower 7 via the fixture plate 15 . The compressive force required for the concrete tower 7 made of PC is ensured by combining the tension introduced in advance during the production on land and the force transmitted from the ground anchor 31 via the fixing plate 15 . The ground anchor 31 has a function as a weight that applies apparent dead weight to increase the stability of the gravity foundation 4 and a function that applies a compressive force to the concrete tower 7 .

FIG. 5 is a diagram showing the process of filling the filling sands 37-1 and 37-2. In the process shown in FIG. 5, the filling hole 19 of the fixing plate 15 is used to fill the inside 9 of the concrete tower 7 with filling sand 37-1 as the first filling material. In addition, filling sand 37-2, which is the second filling material, is filled into the hollow portion 5 of the direct foundation 3 using a filling hole (not shown) provided in the direct foundation 3. As shown in FIG. This completes the foundation structure 39 for offshore wind power generation.

FIG. 6 is a diagram showing a process of installing the tower 41 (windmill tower) on the concrete tower 7. As shown in FIG. After the foundation structure 39 is completed, the flange 43 at the upper end of the concrete tower 7 and the flange 45 at the lower end of the tower 41 of the wind turbine are joined to install the tower 41 on top of the concrete tower 7 .

In the foundation structure 39, the specifications such as the dimensions of the spread foundation 3 and the weight of the filling sand 37-2, and the number and tension of the ground anchors 31 are the wave forces assumed to act on the foundation structure 39 when the wind turbine is in service. Considering the size, etc., it is determined by examining the balance so that it will be the optimum solution for ensuring stability against overturning.

Thus, in the foundation structure 39 of the first embodiment, since the spread foundation 3 and the concrete tower 7 are integrally made of concrete and manufactured, the manufacturing cost can be reduced compared to the case where the tower is made of steel. , the reinforcement of the spread foundation 3 for stress transmission from the concrete tower 7 can be minimized. In addition, since the spread foundation 3 and the concrete tower 7 are integrated on land, there is no joint work on the sea, and work using an SEP (self-elevating work barge) can be minimized. Furthermore, by towing the gravity foundation 4 to the site while the hollow portion 5 of the spread foundation 3 and the interior 9 of the concrete tower 7 are hollow, the total weight can be reduced and the applicability to a crane ship or the like can be enhanced. .

In the first embodiment, after the gravity foundation 4 is set, filling sand 37-1 is filled in the interior 9 of the concrete tower 7, and filling sand 37-2 is filled in the cavity 5 of the direct foundation 3. The total weight of the base structure 39 can be increased. In addition, the spread foundation 3 and the ground anchor 31 are used together, and by introducing the vertical force required to satisfy the stability against overturning and pulling out due to wave force etc. to the ground anchor 31, the force on the pushing side can be reduced. The pull-out side force can be directly transmitted from the foundation 3 to the rock 22 and resisted by the ground anchor 31. - 特許庁Therefore, even if the spread foundation 3 installed on the bedrock 22 on the seabed is greatly reduced in size, it is possible to maintain stability against overturning due to wave force or the like during use.

In the foundation structure 39, by fixing the upper end of the ground anchor 31 to the fixing plate 15 formed on the sea portion of the concrete tower 7, the ground anchor 31 can be constructed without underwater diver work. Further, by embedding the sleeve pipe 11 in the direct foundation 3, the ground anchor 31 can be easily penetrated through the direct foundation 3. Furthermore, by arranging the ground anchor 31 so as to penetrate the inside of the concrete tower 7, it is possible to protect the concrete tower 7 from corrosion due to seawater and damage due to drifting objects.

Other examples of the present invention will be described below as second to fourth embodiments. In each embodiment, points different from the embodiments described so far will be described, and descriptions of similar configurations will be omitted by attaching the same reference numerals in the drawings and the like. In addition, the configurations described in each embodiment, including the first embodiment, can be combined as necessary.

A second embodiment will be described. FIG. 7 shows a base structure 39a according to a second embodiment of the invention.

This foundation structure 39a is mainly different from the foundation structure 39 of the first embodiment in that the direct foundation 3a is not provided with a cavity and is not filled with filling sand. As a result of examining the balance between the spread foundation and the ground anchor so as to ensure stability against overturning in consideration of the magnitude of the wave force that is assumed to act during service, it was found that the spread foundation 3a was placed in the middle like the foundation structure 39a. In some cases, the optimum solution is to have a specification that does not provide packing sand.

When constructing the foundation structure 39a, the direct foundation 3a and the concrete tower 7 are integrated on land in the same procedure as in the first embodiment, and the gravity foundation 4a is manufactured and installed on the bedrock 22, and the ground anchor 31 to fix the gravity foundation 4a to the bedrock 22. After that, the inside 9 of the concrete tower 7 is filled with filling sand 37-1.

Also in the base structure 39a of the second embodiment, the same effects as those of the base structure 39 of the first embodiment can be obtained. In the foundation structure 39a, by making the spread foundation 3a smaller than the spread foundation 3 of the foundation structure 39, the influence of wave force is reduced.

A third embodiment will be described. FIG. 8 is a diagram showing a base structure 39b according to a third embodiment of the invention.

This base structure 39b mainly differs from the base structure 39 of the first embodiment in that no ground anchors are arranged. As a result of examining the balance between filling materials and ground anchors so as to ensure stability against overturning in consideration of the magnitude of the wave force that is assumed to act during service, ground anchors will not be installed like the foundation structure 39b. may be the optimum solution.

Since no ground anchor is arranged in the foundation structure 39b, no fixing plate is provided in the interior 9 of the concrete tower 7, and no sheath pipe is buried in the direct foundation 3b. The direct foundation 3b is provided with a cavity 5b.

When constructing the foundation structure 39b, the direct foundation 3b and the concrete tower 7 are integrated on land to form the gravity foundation 4b and set it on the bedrock 22 in the same procedure as in the first embodiment. The concrete tower 7 of the foundation structure 39b is made of PC, and compressive force is introduced on land. After that, the inside 9 of the concrete tower 7 is filled with filling sand 37b-1, and the cavity 5b of the direct foundation 3b is filled with filling sand 37b-2.

In the third embodiment, since the interior 9 of the concrete tower 7 is filled with the filling sand 37-1, compared to the case where the filling sand 37-1 is not filled, even if the spread foundation 3b is greatly reduced in size, the foundation The total weight of the structure 39b can be ensured, and stability can be maintained against overturning due to wave force or the like.

In the foundation structure 39b as well, the concrete direct foundation 3b and the concrete tower 7 are integrated on land to produce the gravity foundation 4b. By towing the type foundation 4b to the site and filling it with filling sand 37b-1 and 37b-2 after sinking, the same effect as in the first embodiment can be obtained.

A fourth embodiment will be described. FIG. 9 is a diagram showing a base structure 39c according to a fourth embodiment of the invention.

This foundation structure 39c is mainly different from the foundation structure 39 of the first embodiment in that the direct foundation 3c has a cutting edge 49 on the outer edge of the lower surface.

The seabed ground on which the foundation structure 39c is constructed has a sedimentary layer 47 on the surface layer, and a supporting bedrock 22a below the sedimentary layer 47. As shown in FIG. In the base structure 39c, the lower end of the cutting edge 49 reaches the supporting bedrock 22a. Also, the anchor body 33c of the ground anchor 31c is formed in the supporting bedrock 22a.

When constructing the foundation structure 39c, the direct foundation 3c and the concrete tower 7 are integrated on land to form the gravity foundation 4c and sink it on the seabed in the same procedure as in the first embodiment. At this point, the lower end of the cutting edge 49 has not reached the supporting bedrock 22a.

After the gravity foundation 4c is laid down, the ground anchor 31c is driven using the guide hole 17 and the sheath pipe 11 as guides in the same manner as in the first embodiment. The lower end of the ground anchor 31c is fixed to the supporting rock 22a by the anchor body 33c, and the upper end is fixed to the fixing plate 15 by the fixture 35. As shown in FIG. The cutting edge 49 of the direct foundation 3c presses into the sediment layer 47 by introducing tension when fixing the ground anchor 31c. At this time, the sediment layer 47 around the cutting edge 49 may be excavated as necessary in order to ensure that the lower end of the cutting edge 49 reaches the supporting rock 22a.

After the gravitational foundation 4c is fixed to the supporting rock 22a by the ground anchor 31c with the cutting edge 49 reaching the supporting rock 22a, the interior 9 of the concrete tower 7 is filled with filling sand 37-1 to fill the cavity of the direct foundation 3c. The filling sand 37-2 is filled in the part 5 to complete the basic structure 39c, and the tower 41 is installed on the upper part of the concrete tower 7.

According to the fourth embodiment, effects similar to those of the first embodiment are obtained. In addition, in the fourth embodiment, since the foundation structure 39c can be constructed without excavating the surface sediment layer 47 of the seabed ground by providing the cutting edge 49 in the spread foundation 3c, the sediment layer 47 can be excavated. The construction period can be shortened and the construction cost can be greatly reduced compared to the case where the foundation structure is constructed by The ground anchor 31c in the fourth embodiment functions as a weight that adds apparent self-weight in order to increase the stability of the gravity foundation 4c described in the first embodiment, and gives a compressive force to the concrete tower 7. In addition to the function, it has the function of pressing the gravity foundation 4c into the deposited layer 47 by introducing a tension force.

In the first to fourth embodiments, filling sand was used as the first filling material to be filled inside the concrete tower and the second filling material to be filled in the cavity of the direct foundation. , The filling material is not limited to sand. For example, the filling material may be fluidized soil using earth and sand material generated on-site by drilling the seabed ground such as the bedrock 22 .

Although the concrete tower 7 is made of PC in the first, second and fourth embodiments, it may be made of RC. In the case of RC, no tension force is introduced into the concrete tower 7 at the time of manufacture, and the force transmitted to the concrete tower 7 via the fixing plate 15 from the ground anchor for fixing the direct foundation and the concrete tower 7 to the seabed ground. Ensure the necessary compression force.

In the first, second and fourth embodiments, the concrete tower 7 and the direct foundation are filled with filling sand after the ground anchor is driven to fix the gravity foundation to the seabed ground. After filling the foundation with filling sand, the ground anchor may be driven to fix the gravity foundation to the seabed ground. In this case, it is desirable to arrange a sheath pipe extending from the guide hole 17 to the sheath pipe 11 in the interior 9 of the concrete tower 7, and to fill the exterior of the sheath pipe with filling sand.

In the infrastructure of the first, second and fourth embodiments, the ground anchor may incorporate a fiber optic sensor and connect the fiber optic sensor to the controller. By measuring the tension of the ground anchor with an optical fiber sensor and transmitting the measured tension value from the control device when the offshore wind turbine is in service, it is possible to remotely manage problems with the ground anchor and ensure the safety of the foundation structure. Measurement of the tension is not limited to the optical fiber sensor, and may be performed by a sensor using magnetism.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope of the technical ideas disclosed in the present application, and these naturally belong to the technical scope of the present invention. Understood.

1……Land yard 3, 3a, 3b, 3c……Spread foundation 4, 4a, 4b, 4c……Gravity foundation 5, 5b……Cavity 7……Concrete tower 9……Inside 11......Sleeve tube 13...Lid 14...Moving means 15...Fixation plate 17...Guide hole 19...Filling hole 21...Sea surface 22, 22a...Rock 23... ……Temporary floating body 24……Towing wire 25……Deck 27……Crawler drill 29……Casing pipe 31……Ground anchor 33……Anchor body 35……Fixture 37-1, 37-2, 37b-1, 37b-2 Filling sand 39, 39a, 39b, 39c Foundation structure 41 Tower 43, 45 Flange 47 Deposit layer 49 …cutting edge

Claims (8)

A foundation structure for offshore wind power generation, comprising:
Concrete spread foundation installed on the seabed,
a concrete tower integrated with the spread foundation and having a wind turbine tower installed thereon;
and
The inside of the concrete tower is filled with a first filling material ,
The spread foundation and the concrete tower are fixed to the seabed ground by a ground anchor that penetrates the inside of the concrete tower,
A foundation structure for offshore wind power generation , wherein one end of the ground anchor is anchored to the seabed, and the other end of the ground anchor is anchored to an anchoring portion formed on the sea portion of the concrete tower . 2. The foundation structure for offshore wind power generation according to claim 1 , wherein the fixing portion is fixed inside the concrete tower above the first filling material. 3. The offshore wind power generation system according to claim 1 , wherein a sheath pipe is embedded in said spread foundation, and said ground anchor penetrates said sheath pipe and is fixed to said seabed ground. foundation structure. The foundation structure for offshore wind power generation according to any one of claims 1 to 3 , wherein the spread foundation has a hollow portion, and the hollow portion is filled with a second filling material. A construction method for a foundation structure for offshore wind power generation, comprising:
A step a of integrally manufacturing a spread foundation and a concrete tower on which a wind turbine tower is installed on land using concrete;
Step b of towing the spread foundation and the concrete tower to a site and sinking them to the seabed;
a step c of filling the interior of the concrete tower with a first filling material;
a step d of fixing the spread foundation and the concrete tower to the seabed ground by a ground anchor penetrating the inside of the concrete tower ;
and
A foundation for offshore wind power generation , wherein in the step d, one end of the ground anchor is fixed to the seabed ground, and the other end of the ground anchor is fixed to a fixing portion formed on the sea portion of the concrete tower. Construction method of structure. 6. The method of constructing a foundation structure for offshore wind power generation according to claim 5 , wherein the fixing portion is fixed inside the concrete tower above the first filling material. 7. The offshore wind power plant according to claim 5 , wherein a sheath pipe is embedded in the spread foundation, and the ground anchor is fixed to the seabed ground by inserting the ground anchor through the sheath pipe in the step d. Construction method of foundation structure for power generation. 8. The foundation for offshore wind power generation according to any one of claims 5 to 7 , wherein the spread foundation has a hollow portion, and the hollow portion is filled with a second filling material in the step c. Construction method of structure.

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