JP2021179113A - Foundation reinforcement method, and structure - Google Patents
Foundation reinforcement method, and structure Download PDFInfo
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- JP2021179113A JP2021179113A JP2020084637A JP2020084637A JP2021179113A JP 2021179113 A JP2021179113 A JP 2021179113A JP 2020084637 A JP2020084637 A JP 2020084637A JP 2020084637 A JP2020084637 A JP 2020084637A JP 2021179113 A JP2021179113 A JP 2021179113A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 230000002787 reinforcement Effects 0.000 title abstract 2
- 238000007710 freezing Methods 0.000 claims abstract description 49
- 230000008014 freezing Effects 0.000 claims abstract description 49
- 239000002344 surface layer Substances 0.000 claims abstract description 41
- 238000010248 power generation Methods 0.000 claims abstract description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000001816 cooling Methods 0.000 claims abstract description 8
- 239000000110 cooling liquid Substances 0.000 claims abstract description 6
- 238000009991 scouring Methods 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 22
- 230000002265 prevention Effects 0.000 claims description 20
- 239000002826 coolant Substances 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 230000003014 reinforcing effect Effects 0.000 claims description 13
- 238000005259 measurement Methods 0.000 claims description 3
- 239000002689 soil Substances 0.000 description 27
- 238000010586 diagram Methods 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010426 asphalt Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 239000010410 layer Substances 0.000 description 5
- 230000002093 peripheral effect Effects 0.000 description 4
- 239000004575 stone Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000013307 optical fiber Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/727—Offshore wind turbines
Landscapes
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
- Foundations (AREA)
- Wind Motors (AREA)
Abstract
Description
本発明は、基礎の補強方法および構造物に関するものである。 The present invention relates to a method of reinforcing a foundation and a structure.
従来、洋上風力発電設備などの構造物を構築する際には、基礎を水底に設置している。水底に設置した基礎には地震や波力などの水平力が作用するため、通常は基礎を地盤の必要深さまで根入れすることで水平力に対する支持力を確保する。これに対し、基礎構造物内の圧力を下げてサクション圧を常時作用させることで引き抜きに対する抵抗を増大させる方法がある（例えば、特許文献１参照）。 Conventionally, when constructing structures such as offshore wind power generation facilities, the foundation is installed on the bottom of the water. Since horizontal forces such as earthquakes and wave forces act on the foundation installed on the bottom of the water, the foundation is usually rooted to the required depth of the ground to secure the bearing capacity for the horizontal force. On the other hand, there is a method of increasing the resistance to extraction by lowering the pressure in the foundation structure and constantly applying the suction pressure (see, for example, Patent Document 1).
また、水底の基礎の周囲の地盤で水流や波などによって土砂が洗い流される洗掘現象が発生すると基礎の性能が低下するため、砕石などの洗掘防止部材を水中基礎の周囲に設置している（例えば、特許文献２参照）。洗堀現象が発生すると、構造物に接続された水底ケーブルが水中で変形を繰り返して損傷するおそれもある。 In addition, if a scouring phenomenon occurs in which the earth and sand are washed away by water currents or waves in the ground around the foundation of the bottom of the water, the performance of the foundation will deteriorate, so crushed stones and other scouring prevention members are installed around the underwater foundation. (See, for example, Patent Document 2). When the scouring phenomenon occurs, the submarine cable connected to the structure may be repeatedly deformed and damaged in water.
しかしながら、サクション圧を作用させることができない地盤の場合には、引き抜き抵抗の確保を行うために、基礎を深くまで根入れする必要があった。また、基礎の周りに洗堀が生じると、設計通りの支持力を得ることができなくなる。このため、砕石などの洗堀防止部材を用いて洗堀を防止する必要があるが、洗堀防止部材を大量に水域まで運搬する必要がある。 However, in the case of the ground where suction pressure cannot be applied, it is necessary to deeply root the foundation in order to secure the pull-out resistance. In addition, if a scouring occurs around the foundation, it will not be possible to obtain the bearing capacity as designed. For this reason, it is necessary to prevent scouring by using a scouring prevention member such as crushed stone, but it is necessary to transport a large amount of scouring prevention member to the water area.
本発明は、前述した問題点に鑑みてなされたものであり、その目的とすることは、基礎の根入れ深さを浅くすることができる基礎の補強方法および構造物を提供することである。 The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method and a structure for reinforcing a foundation, which can make the depth of the foundation shallow.
前述した目的を達成するために第１の発明は、水底の地盤に構造物の基礎を設置する工程ａと、前記基礎の内側に配置された凍結部材に冷却液を循環させて、前記基礎の周囲の地盤を凍結する工程ｂと、を具備することを特徴とする基礎の補強方法である。 In order to achieve the above-mentioned object, the first invention is a step a of installing a foundation of a structure on the ground of the bottom of the water, and a cooling liquid is circulated through a freezing member arranged inside the foundation to form the foundation. It is a method of reinforcing a foundation, which comprises a step b of freezing the surrounding ground.
第１の発明によれば、基礎の周囲の地盤の表層を凍結することで洗堀防止工を容易に形成することができる。また、基礎の周囲の地盤を凍結することで、凍結による付着強度が付加されて基礎と地盤との摩擦力が増大するので、凍結しない場合と比較して基礎の根入れ深さが浅くても水平力に対する抵抗力を確保することができる。 According to the first invention, the scouring prevention work can be easily formed by freezing the surface layer of the ground around the foundation. In addition, by freezing the ground around the foundation, the adhesion strength due to freezing is added and the frictional force between the foundation and the ground increases, so even if the foundation is shallower than when it does not freeze. It is possible to secure resistance to horizontal force.
前記構造物が洋上風力発電設備であり、前記工程ｂで、前記洋上風力発電設備の稼働で生み出される発電エネルギーの一部を用いて前記冷却液の温度を調整してもよい。
これにより、洋上風力発電設備の稼働時には他の電源を用いずに基礎の周囲の地盤を凍結することができる。
The structure is an offshore wind power generation facility, and the temperature of the coolant may be adjusted by using a part of the power generation energy generated by the operation of the offshore wind power generation facility in the step b.
As a result, the ground around the foundation can be frozen without using other power sources when the offshore wind power generation facility is in operation.
前記地盤の表層付近の冷却能力が、他の部分よりも大きいことが望ましい。
これにより、基礎の周囲の地盤の表層を確実に凍結することができる。
It is desirable that the cooling capacity near the surface layer of the ground is larger than that of other parts.
This ensures that the surface layer of the ground around the foundation is frozen.
前記基礎の周囲の地盤上に金属部材が配置されてもよい。前記金属部材は例えば水底ケーブルを被覆する網材である。
熱伝導率の高い金属部材を配置することにより、冷却液から金属部材を介して基礎の周囲の地盤の表層を効率良く冷却して凍結することができるので、洗堀の発生が最小限に抑制される。また、金属部材でケーブルを被覆することで、ケーブル付近の地盤を他所に先行して凍結することができるので、ケーブルの水中での変形による損傷が防止される。
A metal member may be placed on the ground around the foundation. The metal member is, for example, a net material that covers a submarine cable.
By arranging a metal member with high thermal conductivity, the surface layer of the ground around the foundation can be efficiently cooled and frozen from the coolant through the metal member, so the occurrence of scouring is minimized. Will be done. Further, by covering the cable with a metal member, the ground near the cable can be frozen in advance of other places, so that damage due to deformation of the cable in water can be prevented.
前記工程ｂで、前記基礎の近傍の地盤に設置された計測手段を用いて前記地盤の温度を計測し、計測結果に基づいて前記冷却液の温度を設定してもよい。
これにより、温度を詳細に管理することができる。
In the step b, the temperature of the ground may be measured by using a measuring means installed on the ground near the foundation, and the temperature of the coolant may be set based on the measurement result.
This makes it possible to control the temperature in detail.
前記工程ｂで、前記基礎に作用する波または流れの大きさに応じて前記冷却液の温度を設定してもよい。
これにより、温度を簡易に管理することができる。
In step b, the temperature of the coolant may be set according to the magnitude of the wave or flow acting on the foundation.
This makes it possible to easily control the temperature.
第２の発明は、水底の地盤に設置された基礎と、前記基礎の内側に配置された凍結部材と、を具備し、前記凍結部材に循環させた冷却液によって前記基礎の周囲の地盤が凍結されたことを特徴とする構造物である。 The second invention includes a foundation installed on the ground at the bottom of the water and a freezing member arranged inside the foundation, and the ground around the foundation is frozen by the cooling liquid circulated in the freezing member. It is a structure characterized by being done.
第２の発明によれば、基礎の周囲の地盤の表層が凍結されることで洗堀防止工が容易に形成される。また、基礎の周囲の地盤が凍結されることで、凍結による付着強度が付加されて基礎と地盤との摩擦力が増大するので、基礎の根入れ深さを浅くすることができる。 According to the second invention, the scouring prevention work is easily formed by freezing the surface layer of the ground around the foundation. Further, when the ground around the foundation is frozen, the adhesion strength due to freezing is added and the frictional force between the foundation and the ground is increased, so that the depth of the foundation can be made shallow.
前記構造物が洋上風力発電設備であり、前記基礎の周囲の地盤上に洗堀防止部材が設置されてもよい。
前記基礎は例えばモノパイルである。
モノパイル等の基礎の周囲の地盤の表層が凍結され、その上に洗堀防止部材が設置されることで、洗堀をより確実に防止することができる。
The structure is an offshore wind power generation facility, and a scouring prevention member may be installed on the ground around the foundation.
The basis is, for example, a monopile.
By freezing the surface layer of the ground around the foundation such as monopile and installing a scouring prevention member on it, scouring can be prevented more reliably.
本発明によれば、基礎の根入れ深さを浅くすることができる基礎の補強方法および構造物を提供できる。 INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method and a structure for reinforcing a foundation, which can make the depth of the foundation shallow.
以下、図面に基づいて本発明の好適な実施形態について詳細に説明する。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
図１は洋上風力発電設備５の構築方法を示す図である。図１（ａ）はモノパイル１を設置する工程を示す図、図１（ｂ）はモノパイル１を補強する工程を示す図、図１（ｃ）は上部構造７を設置する工程を示す図である。 FIG. 1 is a diagram showing a method of constructing an offshore wind power generation facility 5. 1A is a diagram showing a process of installing the monopile 1, FIG. 1B is a diagram showing a process of reinforcing the monopile 1, and FIG. 1C is a diagram showing a process of installing the superstructure 7. ..
洋上風力発電設備５を構築するには、まず図１（ａ）に示すように水底の地盤３にモノパイル１を設置する。モノパイル１は、例えば鋼管杭である。モノパイル１は例えば中掘り工法によって地盤３に貫入され、内部には水が満たされる。 To construct the offshore wind power generation facility 5, first, as shown in FIG. 1A, a monopile 1 is installed on the ground 3 at the bottom of the water. The monopile 1 is, for example, a steel pipe pile. The monopile 1 is penetrated into the ground 3 by, for example, a middle digging method, and the inside is filled with water.
図２は地盤３に設置されたモノパイル１の鉛直断面図である。図３は地盤３に設置されたモノパイル１の水平断面図である。図３（ａ）は図２のＡ−Ａ線断面図、図３（ｂ）は図２のＢ−Ｂ線断面図である。 FIG. 2 is a vertical cross-sectional view of the monopile 1 installed on the ground 3. FIG. 3 is a horizontal cross-sectional view of the monopile 1 installed on the ground 3. 3A is a sectional view taken along line AA of FIG. 2, and FIG. 3B is a sectional view taken along line BB of FIG.
図２、図３に示すように、モノパイル１の内周面にはあらかじめ鉛直方向の凍結管１１、水平方向の凍結管１３が貼付される。凍結管１１はモノパイル１の軸方向に延伸するように、モノパイル１の周方向に一定の間隔をおいて配置される。凍結管１３は地盤３の表層１５付近においてモノパイル１の周方向に延伸するように配置される。凍結管１１、１３は例えばアルミ製のマイクロチャネルであり、図示しないセメント系材料で防護してもよい。凍結管１１の海底より上に位置する部分は、図示しない断熱材で被覆される。 As shown in FIGS. 2 and 3, a vertical freezing tube 11 and a horizontal freezing tube 13 are attached to the inner peripheral surface of the monopile 1 in advance. The freezing tubes 11 are arranged at regular intervals in the circumferential direction of the monopile 1 so as to extend in the axial direction of the monopile 1. The freezing pipe 13 is arranged so as to extend in the circumferential direction of the monopile 1 in the vicinity of the surface layer 15 of the ground 3. The freezing tubes 11 and 13 are, for example, aluminum microchannels, and may be protected by a cement-based material (not shown). The portion of the freezing tube 11 located above the seabed is covered with a heat insulating material (not shown).
地盤３にモノパイル１を設置したら、図１（ｂ）に示すようにモノパイル１にデッキを固定し、冷却液の送り出しや制御に係わる装置が搭載された冷凍設備２９をデッキ上に設置する。そして、モノパイル１の周囲の地盤３を凍結して凍土９を形成する。凍土９を形成するには、図示しない外部電源等を用いて冷凍設備２９により温度制御された冷却液を凍結管１１、１３に循環させる。冷凍設備２９は遠隔での運転制御が可能である。上記したようにモノパイル１は熱伝導率の高い鋼製であり凍結管１１、１３はその内周面に貼付されているので、冷却液の温度を低下させるとモノパイル１は同一深さにおいて全周が略均等に冷却され、モノパイル１の外側の地盤３に水平断面が略円形の凍土９が形成される。 After installing the monopile 1 on the ground 3, the deck is fixed to the monopile 1 as shown in FIG. 1 (b), and the refrigerating equipment 29 equipped with the device related to the delivery and control of the coolant is installed on the deck. Then, the ground 3 around the monopile 1 is frozen to form the frozen soil 9. In order to form the frozen soil 9, a cooling liquid whose temperature is controlled by the freezing equipment 29 is circulated through the freezing pipes 11 and 13 using an external power source (not shown) or the like. The refrigerating equipment 29 can be remotely controlled. As described above, the monopile 1 is made of steel having high thermal conductivity, and the freezing tubes 11 and 13 are attached to the inner peripheral surfaces thereof. Therefore, when the temperature of the coolant is lowered, the monopile 1 has the entire circumference at the same depth. Is cooled substantially evenly, and frozen soil 9 having a substantially circular horizontal cross section is formed on the ground 3 outside the monopile 1.
地盤３の表層１５付近には凍結管１１に加えて周方向に凍結管１３が配置されるので、表層１５付近の冷却能力は他の部分よりも大きい。そのため、地盤３の表層１５では他の部分よりも広範囲に凍土９が形成される。モノパイル１の周囲の地盤３の表層１５の凍土９は、波や流れに対する洗堀防止工９ａとして機能する。なお、凍結管１１を周方向に向けて屈曲させることで地盤３の表層１５近傍の冷却能力を高めてもよい。 Since the freezing pipe 13 is arranged in the circumferential direction in addition to the freezing pipe 11 in the vicinity of the surface layer 15 of the ground 3, the cooling capacity in the vicinity of the surface layer 15 is larger than that of the other parts. Therefore, the frozen soil 9 is formed in a wider area on the surface layer 15 of the ground 3 than in other portions. The frozen soil 9 on the surface layer 15 of the ground 3 around the monopile 1 functions as a moat prevention work 9a against waves and currents. The cooling capacity in the vicinity of the surface layer 15 of the ground 3 may be increased by bending the freezing pipe 11 in the circumferential direction.
図４は、図１（ｂ）に示すモノパイル１付近を上方から見た図である。地盤３の表層１５付近での凍土９の径は、モノパイル１の径の３〜５倍程度とすることが望ましい。地盤３の表層１５のモノパイル１の近傍には海底温度計等の温度計測手段２７が設置されており、温度計測手段２７を用いて地盤３の表層１５の温度を計測すること表層１５の凍土９が所望の範囲まで形成されているかどうかを判定することができる。 FIG. 4 is a view of the vicinity of the monopile 1 shown in FIG. 1 (b) as viewed from above. It is desirable that the diameter of the frozen soil 9 near the surface layer 15 of the ground 3 is about 3 to 5 times the diameter of the monopile 1. A temperature measuring means 27 such as a seabed thermometer is installed in the vicinity of the monopile 1 of the surface layer 15 of the ground 3, and the temperature of the surface layer 15 of the ground 3 is measured by using the temperature measuring means 27. Can be determined whether or not is formed to a desired range.
地盤３の表層１５より下方の部分では凍結管１１のみが配置されるので、冷却能力は地盤３の表層１５付近よりも小さい。そのため、地盤３の表層１５より下方の部分では表層１５よりも狭い範囲に凍土９が形成される。モノパイル１の周囲に形成された凍土９は、モノパイル１と地盤３との間に凍結による付着強度を付加してモノパイル１と地盤３との摩擦力を増大させ、モノパイル１の水平力に対する抵抗力の向上に寄与する。 Since only the freezing pipe 11 is arranged in the portion below the surface layer 15 of the ground 3, the cooling capacity is smaller than that in the vicinity of the surface layer 15 of the ground 3. Therefore, in the portion of the ground 3 below the surface layer 15, the frozen soil 9 is formed in a range narrower than the surface layer 15. The frozen soil 9 formed around the monopile 1 adds adhesion strength due to freezing between the monopile 1 and the ground 3 to increase the frictional force between the monopile 1 and the ground 3, and resists the horizontal force of the monopile 1. Contributes to the improvement of.
凍土９を形成する際には、温度計測手段２７や、モノパイル１に貼付した図示しない光ファイバ等を用いて地盤３の温度を計測し、凍結管１１、１３に循環させる冷却液の温度を地盤３の温度の計測結果に基づいて設定してもよい。これにより温度を詳細に管理することができる。また、モノパイル１に波または流れが作用する時期を把握しておき、凍結管１１、１３に循環させる冷却液の温度を予想される波や流れの大きさに応じて設定してもよい。これにより、例えば大きな波や流れが作用すると予想される時期には低い温度に設定するなど、温度を簡易に管理することができる。このようにして冷却液の温度を管理すれば、凍土９の形成不足や過度な形成を防止することができる。温度計測手段２７や光ファイバ等による温度計測や、冷却液の設定温度の制御は、遠隔操作によって行ってもよい。 When forming the frozen soil 9, the temperature of the ground 3 is measured using a temperature measuring means 27, an optical fiber (not shown) attached to the monopile 1, and the temperature of the coolant circulating in the freezing pipes 11 and 13 is set to the ground. It may be set based on the measurement result of the temperature of 3. This makes it possible to control the temperature in detail. Further, the time when the wave or the flow acts on the monopile 1 may be grasped, and the temperature of the coolant circulating in the freezing tubes 11 and 13 may be set according to the expected wave or the magnitude of the flow. This makes it possible to easily control the temperature, for example, by setting the temperature to a low temperature when a large wave or flow is expected to act. By controlling the temperature of the coolant in this way, it is possible to prevent insufficient formation or excessive formation of the frozen soil 9. The temperature may be measured by the temperature measuring means 27, an optical fiber, or the like, and the set temperature of the coolant may be controlled by remote control.
モノパイル１の周囲の地盤３の所望の範囲に凍土９を形成したら、図１（ｃ）に示すようにモノパイル１上に上部構造７を設置して洋上風力発電設備５を完成し、使用する。洋上風力発電設備５の供用期間中は、洋上風力発電設備５の稼働で生み出される発電エネルギーの一部を用いて冷却液を設定温度に調整する。設定温度は、上記したように温度計測手段２７による地盤３の温度計測結果や予想される波や流れの大きさに応じて決めることが望ましい。 After forming the frozen soil 9 in the desired range of the ground 3 around the monopile 1, the superstructure 7 is installed on the monopile 1 as shown in FIG. 1 (c) to complete the offshore wind power generation facility 5 for use. During the service period of the offshore wind power generation facility 5, the coolant is adjusted to a set temperature by using a part of the power generation energy generated by the operation of the offshore wind power generation facility 5. As described above, it is desirable that the set temperature is determined according to the temperature measurement result of the ground 3 by the temperature measuring means 27 and the expected magnitude of the wave or flow.
第１の実施形態によれば、モノパイル１の周囲の地盤３の表層１５を凍結することで洗堀防止工９ａを容易に形成することができる。また、地盤３の表層１５付近にモノパイル１の周方向の凍結管１３を配置することで、表層１５付近の冷却能力を他の部分よりも大きくして洗堀防止工９ａを広範囲に確実に形成することができる。凍土９によって洗堀防止工９ａを形成すれば、地震や高波による水底地盤の液状化で水底表面が沈下する現象を緩和することができる。 According to the first embodiment, the scouring prevention work 9a can be easily formed by freezing the surface layer 15 of the ground 3 around the monopile 1. Further, by arranging the freezing pipe 13 in the circumferential direction of the monopile 1 near the surface layer 15 of the ground 3, the cooling capacity near the surface layer 15 is made larger than other parts, and the scouring prevention work 9a is surely formed in a wide range. can do. If the scouring prevention work 9a is formed by the frozen soil 9, the phenomenon that the surface of the bottom of the water sinks due to the liquefaction of the bottom of the water due to an earthquake or high waves can be alleviated.
第１の実施形態によれば、モノパイル１の周囲の地盤３を凍結してモノパイル１と地盤３との摩擦力を増大させることで、凍結しない場合と比較してモノパイル１の根入れ深さが浅くても水平力に対する抵抗力を確保することができる。従来のサクション基礎では排水ポンプ設備が故障すると基礎の地耐力が一気に失われるが、第１の実施形態では凍結装置が故障しても凍土９が解凍するまでは地盤３とモノパイル１との摩擦力によって水平力に対する抵抗力を維持できる。 According to the first embodiment, the ground 3 around the monopile 1 is frozen to increase the frictional force between the monopile 1 and the ground 3, so that the depth of penetration of the monopile 1 is increased as compared with the case where the monopile 1 is not frozen. Even if it is shallow, resistance to horizontal force can be secured. In the conventional suction foundation, if the drainage pump equipment fails, the bearing capacity of the foundation is lost at once, but in the first embodiment, even if the freezing device fails, the frictional force between the ground 3 and the monopile 1 until the frozen soil 9 is thawed. Can maintain resistance to horizontal force.
第１の実施形態では、モノパイル１の根入れ深さを浅くし、洗堀防止工９ａを容易に形成することにより、工費が削減され工期が短縮できる。洋上風力発電設備５の供用期間後には、表層１５の凍土９を解凍すれば洗堀防止工９ａを撤去できる。また、モノパイル１は、地下部分の外径が略一定であるため、表層１５を含む地盤３の凍土９を解凍すればモノパイル１の引き抜き抵抗力を低下させて撤去できる。 In the first embodiment, the depth of penetration of the monopile 1 is made shallow, and the washing prevention work 9a is easily formed, so that the work cost can be reduced and the work period can be shortened. After the offshore wind power generation facility 5 is in service, the scouring prevention work 9a can be removed by thawing the frozen soil 9 on the surface layer 15. Further, since the outer diameter of the underground portion of the monopile 1 is substantially constant, if the frozen soil 9 of the ground 3 including the surface layer 15 is thawed, the pull-out resistance of the monopile 1 can be reduced and removed.
第１の実施形態では、洋上風力発電設備５の供用期間中は、洋上風力発電設備５の稼働で生み出される発電エネルギーの一部を冷却液の温度調整に用いるので、他の電源を用いずに地盤３を凍結することができる。 In the first embodiment, during the service period of the offshore wind power generation facility 5, a part of the power generation energy generated by the operation of the offshore wind power generation facility 5 is used for adjusting the temperature of the coolant, so that no other power source is used. The ground 3 can be frozen.
なお、第１の実施形態ではモノパイル１を中掘り工法によって地盤３に設置したが、設置方法はこれに限らず打撃工法によって設置してもよい。 In the first embodiment, the monopile 1 is installed on the ground 3 by the middle digging method, but the installation method is not limited to this and may be installed by the striking method.
モノパイル１に配置される凍結管の位置は図２、図３に示すものに限らない。図５は、凍結管１１がモノパイル１の中央付近に配置された例を示す図である。図５（ａ）は図２のＡ−Ａ線に対応する位置、図５（ｂ）は図２のＢ−Ｂ線に対応する位置での水平断面図である。図５に示す例では、地盤３の表層１５付近を除く部分では凍結管１１がモノパイル１の内側の中央付近に鉛直方向に延伸するように配置され、表層１５付近では凍結管１３が凍結管１１から分岐してモノパイル１の内周面に沿って周回するように配置される。この例ではモノパイル１を地盤３に設置した後に凍結管１１、１３を挿入することが望ましい。 The positions of the freezing tubes arranged in the monopile 1 are not limited to those shown in FIGS. 2 and 3. FIG. 5 is a diagram showing an example in which the freezing tube 11 is arranged near the center of the monopile 1. 5 (a) is a horizontal cross-sectional view at a position corresponding to the line AA of FIG. 2, and FIG. 5 (b) is a horizontal sectional view at a position corresponding to the line BB of FIG. In the example shown in FIG. 5, the freezing tube 11 is arranged so as to extend in the vertical direction near the center inside the monopile 1 except for the vicinity of the surface layer 15 of the ground 3, and the freezing tube 13 is arranged in the vicinity of the surface layer 15 in the freezing tube 11. It is arranged so as to branch from and orbit along the inner peripheral surface of the monopile 1. In this example, it is desirable to insert the freezing tubes 11 and 13 after installing the monopile 1 on the ground 3.
また、水平方向の凍結管１３は必須ではない。モノパイル１に鉛直方向の凍結管１１のみを配置し、凍結管１１の表層１５付近を除く部分に断熱材を設けてもよい。このような配置とした場合にも、表層１５付近の冷却能力が他の部分より大きくなるので、表層１５より下方の部分に対して表層１５付近の地盤３を広範囲に凍結して洗堀防止工９ａを形成することができる。 Further, the freezing tube 13 in the horizontal direction is not essential. Only the freezing tube 11 in the vertical direction may be arranged in the monopile 1, and a heat insulating material may be provided in a portion of the freezing tube 11 other than the vicinity of the surface layer 15. Even with such an arrangement, the cooling capacity near the surface layer 15 is larger than that of other parts, so the ground 3 near the surface layer 15 is frozen extensively with respect to the part below the surface layer 15 to prevent scouring. 9a can be formed.
凍土９の形成範囲は図１に示すものに限らない。図６は、凍土９の形成範囲が異なる例を示す図である。図６（ａ）に示す例では、凍土９がモノパイル１の下端付近を除く範囲に形成される。図６（ｂ）に示す例では、凍土９がモノパイル１の下端付近に球根状に形成される。洗堀防止の効果を得るためには、少なくとも地盤３の表層１５に凍土９が形成される必要がある。表層１５より下方の部分については、引き抜き抵抗力を確保できる程度の範囲に凍土９が形成されればよい。 The formation range of the frozen soil 9 is not limited to that shown in FIG. FIG. 6 is a diagram showing an example in which the formation range of the frozen soil 9 is different. In the example shown in FIG. 6A, the frozen soil 9 is formed in a range excluding the vicinity of the lower end of the monopile 1. In the example shown in FIG. 6B, the frozen soil 9 is formed in a bulb shape near the lower end of the monopile 1. In order to obtain the effect of preventing scouring, it is necessary to form frozen soil 9 at least on the surface layer 15 of the ground 3. For the portion below the surface layer 15, the frozen soil 9 may be formed within a range in which the pull-out resistance can be secured.
以下、本発明の別の例について、第２〜第３の実施形態として説明する。各実施形態はそれまでに説明した実施形態と異なる点について説明し、同様の構成については図等で同じ符号を付すなどして説明を省略する。また、第１の実施形態も含め、各実施形態で説明する構成は必要に応じて組み合わせることができる。 Hereinafter, another example of the present invention will be described as the second to third embodiments. The differences between the embodiments and the embodiments described so far will be described, and the same configurations will be omitted with reference to the same reference numerals in the drawings and the like. Further, the configurations described in each embodiment including the first embodiment can be combined as necessary.
図７は、本発明の第２の実施形態に係る洋上風力発電設備５ａを示す図である。第２の実施形態は、地盤３上に金属部材が配置される点で第１の実施形態と主に異なる。 FIG. 7 is a diagram showing an offshore wind power generation facility 5a according to a second embodiment of the present invention. The second embodiment is mainly different from the first embodiment in that the metal member is arranged on the ground 3.
図７に示すように、洋上風力発電設備５ａでは、モノパイル１から地盤３に延びる水底ケーブル２５が、地盤３上に配置された金属部材である鋼製の網材２３で被覆される。網材２３は平面視で水底ケーブル２５に沿うように放射状に配置される。なお、網材２３及び水底ケーブル２５は、図示したように周方向に等間隔に４カ所に配置されなくてもよく、例えば、少なくとも２カ所に配置されればよく、この場合、互いに１８０度の角度位置でなくてよい。 As shown in FIG. 7, in the offshore wind power generation facility 5a, the underwater cable 25 extending from the monopile 1 to the ground 3 is covered with a steel net material 23 which is a metal member arranged on the ground 3. The net material 23 is arranged radially along the submarine cable 25 in a plan view. The net material 23 and the submarine cable 25 do not have to be arranged at four places at equal intervals in the circumferential direction as shown in the figure, for example, they may be arranged at at least two places, and in this case, they are 180 degrees to each other. It does not have to be an angular position.
第２の実施形態では、熱伝導率の高い鋼製の網材２３を配置することにより、冷却液から網材２３を介してモノパイル１の周囲の地盤３の表層１５を効率良く冷却して凍土９を形成することができるので、洗堀の発生が最小限に抑制される。網材２３で水底ケーブル２５を被覆することにより、水底ケーブル２５付近の地盤３を他所に先行して凍結することができるので、水底ケーブル２５の直下の地盤３が洗堀されず水底ケーブル２５の変形による損傷が防止される。 In the second embodiment, by arranging the steel net material 23 having high thermal conductivity, the surface layer 15 of the ground 3 around the monopile 1 is efficiently cooled from the coolant via the net material 23, and the frozen soil is frozen soil. Since 9 can be formed, the occurrence of scouring is minimized. By covering the submarine cable 25 with the net material 23, the ground 3 near the submarine cable 25 can be frozen in advance of other places, so that the ground 3 directly under the submarine cable 25 is not scoured and the submarine cable 25 is used. Damage due to deformation is prevented.
なお、第２の実施形態では網材２３を平面視で放射状に配置したが、網材２３を平面視でモノパイル１の全周に連続するように環状に配置してもよい。また、金属部材によって、水底ケーブル２５を被覆する形態に限られず、例えば、地盤３上の砕石等によるフィルター層（図示省略）の表層に金属部材が配置されてもよく、地盤３とフィルター層との間に金属部材が配置されてもよい。また、網材２３以外の鋼材を地盤３上（フィルター層上を含む）に沿って配置してもよい。また、金属部材としては、鋼材以外にも、例えば銅材（例えば銅製の網材）を用いてもよい。 In the second embodiment, the net material 23 is arranged radially in a plan view, but the net material 23 may be arranged in a ring shape so as to be continuous with the entire circumference of the monopile 1 in a plan view. Further, the metal member is not limited to the form of covering the submarine cable 25, and for example, the metal member may be arranged on the surface layer of the filter layer (not shown) made of crushed stone or the like on the ground 3, and the ground 3 and the filter layer may be arranged. A metal member may be arranged between the two. Further, a steel material other than the net material 23 may be arranged along the ground 3 (including on the filter layer). Further, as the metal member, for example, a copper material (for example, a copper net material) may be used in addition to the steel material.
図８は、本発明の第３の実施形態に係る洋上風力発電設備を示す図である。第３の実施形態は、地盤３上に洗堀防止部材が配置される点で第１の実施形態と主に異なる。 FIG. 8 is a diagram showing an offshore wind power generation facility according to a third embodiment of the present invention. The third embodiment is mainly different from the first embodiment in that the scouring prevention member is arranged on the ground 3.
図８（ａ）に示すように、洋上風力発電設備５ｂでは、モノパイル１の周囲の地盤３上（フィルター層上を含む）に洗堀防止部材である被覆材１９が配置される。被覆材１９は、例えば網袋に石材を充填したものである。 As shown in FIG. 8A, in the offshore wind power generation facility 5b, the covering material 19 which is a scouring prevention member is arranged on the ground 3 (including the filter layer) around the monopile 1. The covering material 19 is, for example, a net bag filled with a stone material.
図８（ｂ）に示すように、洋上風力発電設備５ｃでは、モノパイル１の周囲の地盤３上（フィルター層上を含む）に洗堀防止部材であるアスファルトマット２１が配置される。アスファルトマット２１は、モノパイル１の外周面との間に隙間が生じないように配置される。 As shown in FIG. 8B, in the offshore wind power generation facility 5c, the asphalt mat 21 which is a scouring prevention member is arranged on the ground 3 (including the filter layer) around the monopile 1. The asphalt mat 21 is arranged so that no gap is formed between the asphalt mat 21 and the outer peripheral surface of the monopile 1.
第３の実施形態では、モノパイル１の周囲の地盤３の表層１５が凍結され、その上に被覆材１９やアスファルトマット２１などの洗堀防止部材が設置されることで、洗堀をより確実に防止することができる。また、地盤３の表層１５が凍結する前には波や流れによってモノパイル１の周囲の地盤３から細粒分が流出するが、洋上風力発電設備５ｃではアスファルトマット２１によって細粒分の流出が防止されることにより表層１５に凍土９を形成しやすくなる。さらに凍土９を形成することにより、洗堀防止部材の高波や強潮流による掃流、転動を抑制できる。 In the third embodiment, the surface layer 15 of the ground 3 around the monopile 1 is frozen, and a scouring prevention member such as a covering material 19 or an asphalt mat 21 is installed on the surface layer 15, so that the scouring can be performed more reliably. Can be prevented. Further, before the surface layer 15 of the ground 3 freezes, fine particles flow out from the ground 3 around the monopile 1 due to waves and currents, but in the offshore wind power generation facility 5c, the asphalt mat 21 prevents the fine particles from flowing out. This facilitates the formation of frozen soil 9 on the surface layer 15. Further, by forming the frozen soil 9, it is possible to suppress the sweeping and rolling of the scouring prevention member due to high waves and strong tidal currents.
第１から第３の実施形態では、モノパイル１を基礎とする洋上風力発電設備について説明したが、本発明の構造物はこれに限らない。本発明の基礎の補強方法は洋上風力発電設備のモノパイル１以外の基礎等にも適用可能である。 In the first to third embodiments, the offshore wind power generation facility based on the monopile 1 has been described, but the structure of the present invention is not limited to this. The method of reinforcing the foundation of the present invention can be applied to foundations other than monopile 1 of offshore wind power generation equipment.
以上、添付図面を参照しながら、本発明に係る好適な実施形態について説明したが、本発明はかかる例に限定されない。当業者であれば、本願で開示した技術的思想の範疇内において、各種の変更例又は修正例に想到し得ることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。 Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person skilled in the art can come up with various modified examples or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.
１………モノパイル
３………地盤
５、５ａ、５ｂ、５ｃ………洋上風力発電設備
７………上部構造
９………凍土
９ａ………凍結防止工
１１、１３………凍結管
１５………表層
１７………径
１９………被覆材
２１………アスファルトマット
２３………網材
２５………水底ケーブル
２７………温度計測手段
２９………冷凍設備
1 ………… Monopile 3 ………… Ground 5, 5a, 5b, 5c ………… Offshore wind power generation equipment 7 ………… Superstructure 9 ………… Frozen soil 9a ………… Freezing prevention work 11, 13 ………… Freezing pipe 15 ………… Surface layer 17 ………… Diameter 19 ………… Covering material 21 ………… Asphalt mat 23 ………… Net material 25 ………… Underwater cable 27 ………… Temperature measuring means 29 ………… Refrigeration equipment
Claims (10)
前記基礎の内側に配置された凍結部材に冷却液を循環させて、前記基礎の周囲の地盤を凍結する工程ｂと、
を具備することを特徴とする基礎の補強方法。 Step a of installing the foundation of the structure on the ground of the bottom of the water,
A step b in which a cooling liquid is circulated through a freezing member arranged inside the foundation to freeze the ground around the foundation.
A method of reinforcing a foundation, characterized in that it is provided with.
前記工程ｂで、前記洋上風力発電設備の稼働で生み出される発電エネルギーの一部を用いて前記冷却液の温度を調整することを特徴とする請求項１記載の基礎の補強方法。 The structure is an offshore wind power generation facility.
The method for reinforcing a foundation according to claim 1, wherein in the step b, the temperature of the coolant is adjusted by using a part of the power generation energy generated by the operation of the offshore wind power generation facility.
前記基礎の内側に配置された凍結部材と、
を具備し、
前記凍結部材に循環させた冷却液によって前記基礎の周囲の地盤が凍結されたことを特徴とする構造物。 The foundation installed on the ground of the bottom of the water and
With the freezing member placed inside the foundation,
Equipped with
A structure characterized in that the ground around the foundation is frozen by the cooling liquid circulated in the freezing member.
前記基礎の周囲の地盤上に洗堀防止部材が設置されたことを特徴とする請求項８記載の構造物。 The structure is an offshore wind power generation facility.
The structure according to claim 8, wherein a scouring prevention member is installed on the ground around the foundation.
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