JP6986119B1 - Scouring prevention structure and scouring prevention method - Google Patents
Scouring prevention structure and scouring prevention method Download PDFInfo
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- 238000009991 scouring Methods 0.000 title claims abstract description 45
- 230000002265 prevention Effects 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 13
- 239000004575 stone Substances 0.000 claims abstract description 225
- 230000002093 peripheral effect Effects 0.000 claims abstract description 8
- 238000009434 installation Methods 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 238000009412 basement excavation Methods 0.000 claims 1
- 238000005406 washing Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 abstract description 9
- 230000000694 effects Effects 0.000 description 6
- 238000010276 construction Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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Abstract
【課題】砕石ユニットを効率的に設置することができる洗掘防止構造および洗掘防止方法を提供する。【解決手段】モノパイル１の周囲の地盤３上にフィルター層５を形成する。そして、複数の砕石ユニット７をモノパイル１の外周面に接するように環状に並べて配置する。次に、水平投影面積が砕石ユニット７より大きい複数の砕石ユニット９を砕石ユニット７の外周に平面視で略六角形状となるように隙間なく並べて配置する。砕石ユニット７と砕石ユニット９とは寸法が異なるため、砕石ユニット７と砕石ユニット９との間には隙間が生じる。その後、水平投影面積が砕石ユニット７より大きい砕石ユニット１１を砕石ユニット７と砕石ユニット９との隙間を塞ぐように配置する。【選択図】図２PROBLEM TO BE SOLVED: To provide a scouring prevention structure and a scouring prevention method capable of efficiently installing a crushed stone unit. SOLUTION: A filter layer 5 is formed on a ground 3 around a monopile 1. Then, a plurality of crushed stone units 7 are arranged in a ring shape so as to be in contact with the outer peripheral surface of the monopile 1. Next, a plurality of crushed stone units 9 having a horizontal projected area larger than that of the crushed stone unit 7 are arranged side by side on the outer periphery of the crushed stone unit 7 so as to have a substantially hexagonal shape in a plan view. Since the crushed stone unit 7 and the crushed stone unit 9 have different dimensions, a gap is formed between the crushed stone unit 7 and the crushed stone unit 9. After that, the crushed stone unit 11 having a horizontal projected area larger than that of the crushed stone unit 7 is arranged so as to close the gap between the crushed stone unit 7 and the crushed stone unit 9. [Selection diagram] Fig. 2
Description
本発明は、袋体に砕石類を充填した砕石ユニットを用いた洗掘防止構造および洗掘防止方法に関するものである。 The present invention relates to a scouring prevention structure and a scouring prevention method using a crushed stone unit in which a bag body is filled with crushed stones.
従来、洋上風力発電設備などの基礎を水中に設置する構造物では、水の流れによって水底面に発生する洗掘現象から構造物を保護するために構造物の周囲に洗掘防止工を設置している。洗掘防止工としては、袋体の中に砕石などの塊状物を充填した砕石ユニットが用いられる（例えば、特許文献１参照）。 Conventionally, in structures where the foundation of offshore wind power generation equipment is installed underwater, scouring prevention work is installed around the structure to protect the structure from the scouring phenomenon that occurs on the bottom of the water due to the flow of water. ing. As the scouring prevention work, a crushed stone unit in which a crushed stone or the like is filled in a bag is used (see, for example, Patent Document 1).
砕石ユニットは水底面に設置すると平面が円形に近い形となるため、隣り合う砕石ユニット同士の間に隙間ができる。隙間があると洗掘防止工としての役割を十分に果たさない恐れがあり、一般的には砕石ユニットを水底面に複数層に重ねて設置し上段と下段の砕石ユニットを噛み合わせて隙間を解消している。 When the crushed stone unit is installed on the bottom of the water, the plane becomes almost circular, so there is a gap between the adjacent crushed stone units. If there is a gap, it may not play a sufficient role as a scouring prevention work, so in general, the crushed stone unit is installed in multiple layers on the bottom of the water and the upper and lower crushed stone units are engaged to eliminate the gap. is doing.
しかしながら、砕石ユニットを複数層に重ねて設置しようとすると、良質な石材等が大量に必要であり、施工時間も長くかかる。近年はより大型の洋上風力発電設備が採用されており、基礎も大きくなることが予想されるため、砕石ユニットを必要最小設置範囲に効率的に設置することが課題となっている。 However, when trying to install the crushed stone unit in a plurality of layers, a large amount of high-quality stone material or the like is required, and the construction time is long. In recent years, larger offshore wind power generation facilities have been adopted, and it is expected that the foundation will also be large, so it is an issue to efficiently install the crushed stone unit within the required minimum installation range.
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、砕石ユニットを効率的に設置することができる洗掘防止構造および洗掘防止方法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 scouring prevention structure and a scouring prevention method capable of efficiently installing a crushed stone unit. ..
前述した目的を達成するために第１の発明は、袋体に砕石類を充填した砕石ユニットを用いた洗掘防止構造であって、水底の地盤に設置された基礎の外周面に接するように環状に並べて配置された複数の第１の砕石ユニットと、複数の前記第１の砕石ユニットの外周の全周に配置された、前記第１の砕石ユニットよりも水平投影面積の大きい複数の第２の砕石ユニットと、前記第１の砕石ユニットと前記第２の砕石ユニットとの隙間を塞ぐように配置された、前記第１の砕石ユニットよりも水平投影面積の大きい第３の砕石ユニットと、を具備することを特徴とする洗掘防止構造である。 In order to achieve the above-mentioned object, the first invention is a scouring prevention structure using a crushed stone unit in which a crushed stone is filled in a bag body so as to be in contact with the outer peripheral surface of a foundation installed on the ground of the bottom of the water. a plurality of first crushed stone units arranged side by side annularly arranged all around the periphery of the plurality of the first crushed stone unit, a second larger plurality of said horizontal projection area than the first crushed stone unit A third crushed stone unit having a larger horizontal projection area than the first crushed stone unit, which is arranged so as to close the gap between the first crushed stone unit and the second crushed stone unit. It is a scouring prevention structure characterized by being provided.
第１の発明によれば、第２の砕石ユニットより水平投影面積の小さい第１の砕石ユニットを用いることで、洗掘が生じやすい基礎の外周付近に砕石ユニットをなるべく隙間なく配置することができる。これにより、基礎設置直後の初期の洗掘発生を軽減することができる。また、大きさの異なる第１の砕石ユニットと第２の砕石ユニットとを並べることで生じた隙間を第３の砕石ユニットで塞ぐことができる。第３の砕石ユニットは、洗掘の危険性が特に高い基礎の近傍において、洗掘防止効果を高めることが期待できる。また、面積の小さい、従って重量の小さい第１の砕石ユニットの移動・飛散防止にも働く。 According to the first invention, by using the first crushed stone unit having a smaller horizontal projected area than the second crushed stone unit, the crushed stone unit can be arranged as close as possible to the outer periphery of the foundation where scouring is likely to occur. .. As a result, it is possible to reduce the occurrence of initial scouring immediately after the foundation is installed. Further, the gap created by arranging the first crushed stone unit and the second crushed stone unit having different sizes can be closed by the third crushed stone unit. The third crushed stone unit can be expected to enhance the scouring prevention effect in the vicinity of the foundation where the risk of scouring is particularly high. It also works to prevent the movement and scattering of the first crushed stone unit, which has a small area and therefore a small weight.
前記第２の砕石ユニットの袋体の容量および前記第３の砕石ユニットの袋体の容量は、前記第１の砕石ユニットの袋体の容量よりも大きいことが望ましい。例えば、前記第２の砕石ユニットの袋体と前記第３の砕石ユニットの袋体とは同じ容量である。
第２の砕石ユニットと第３の砕石ユニットとを同じ容量とすれば、使用する砕石ユニットが２種類となり、砕石ユニットの調達が容易になる。
It is desirable that the capacity of the bag body of the second crushed stone unit and the capacity of the bag body of the third crushed stone unit are larger than the capacity of the bag body of the first crushed stone unit. For example, the bag body of the second crushed stone unit and the bag body of the third crushed stone unit have the same capacity.
If the second crushed stone unit and the third crushed stone unit have the same capacity, the number of types of crushed stone units used will be two, and the procurement of the crushed stone unit will be easy.
複数の前記第２の砕石ユニットが、平面視で略六角形状となるように並べて配置されることが望ましい。さらに好ましくは、前記第２の砕石ユニットは変形可能であり、一つの前記第２の砕石ユニットと隣接する他の前記第２の砕石ユニットとが隙間が生じないように重なり部分を設けて配置される。
これにより、第２の砕石ユニットを確実に隙間なく配置することができるので、第１および第２の砕石ユニットを１層で構成し、第１の砕石ユニットと第２の砕石ユニットとの隙間を第３の砕石ユニットで塞ぐだけの効率的な配置が実現できる。
It is desirable that the plurality of the second crushed stone units are arranged side by side so as to have a substantially hexagonal shape in a plan view. More preferably, the second crushed stone unit is deformable, and one said second crushed stone unit and the other adjacent second crushed stone unit are arranged so as to have an overlapping portion so as not to form a gap. To.
As a result, the second crushed stone unit can be reliably arranged without a gap, so that the first and second crushed stone units are configured by one layer, and the gap between the first crushed stone unit and the second crushed stone unit is formed. Efficient placement can be achieved by simply closing with the third crushed stone unit.
複数の前記第２の砕石ユニットの平面視での設置範囲の外接円の径と内接円の径との平均値が、前記基礎の径の３倍から５倍であることが望ましい。
これにより、洗掘防止効果を確保しつつ、砕石ユニットの設置範囲を縮小することができる。
It is desirable that the average value of the diameter of the circumscribed circle and the diameter of the inscribed circle in the installation range of the plurality of second crushed stone units in a plan view is 3 to 5 times the diameter of the foundation.
As a result, the installation range of the crushed stone unit can be reduced while ensuring the effect of preventing scouring.
複数の前記第２の砕石ユニットと前記水底の地盤との間にフィルター層が配置されてもよい。
これにより、水底の地盤の砂の吸出しを防ぎ、砕石ユニットによる洗掘防止効果を高めることができる。
A filter layer may be arranged between the plurality of the second crushed stone units and the ground on the bottom of the water.
As a result, it is possible to prevent the sand from being sucked out from the ground at the bottom of the water and enhance the effect of preventing scouring by the crushed stone unit.
第２の発明は、袋体に石材を充填した砕石ユニットを用いた洗掘防止方法であって、水底の地盤に設置された基礎の外周面に接するように環状に並べて複数の第１の砕石ユニットを配置する工程と、複数の前記第１の砕石ユニットの外周の全周に、前記第１の砕石ユニットよりも水平投影面積の大きい複数の第２の砕石ユニットを配置する工程と、前記第１の砕石ユニットと前記第２の砕石ユニットとの隙間を塞ぐように、前記第１の砕石ユニットよりも水平投影面積の大きい第３の砕石ユニットを配置する工程と、を具備することを特徴とする洗掘防止方法である。 The second invention is a method for preventing scouring using a crushed stone unit in which a crushed stone is filled in a bag, and a plurality of first crushed stones are arranged in a ring shape so as to be in contact with the outer peripheral surface of a foundation installed on the ground of the bottom of the water. placing the unit, placing the entire circumference of the outer periphery of the plurality of the first crushed stone units, a large plurality of second lithotripsy units of horizontal projection area than the first crushed stone units, the first It is characterized by comprising a step of arranging a third crushed stone unit having a larger horizontal projection area than the first crushed stone unit so as to close the gap between the first crushed stone unit and the second crushed stone unit. It is a method of preventing scouring.
第２の発明によれば、第２の砕石ユニットより水平投影面積の小さい第１の砕石ユニットを用いることで、洗掘が生じやすい基礎の外周付近に砕石ユニットをなるべく隙間なく配置することができる。また、大きさの異なる第１の砕石ユニットと第２の砕石ユニットとを並べることで生じた隙間を第３の砕石ユニットで塞ぐことができる。第３の砕石ユニットは、洗掘の危険性が特に高い基礎の近傍において、洗掘防止効果を高めることが期待できる。また、面積の小さい、従って重量の小さい第１の砕石ユニットの移動・飛散防止にも働く。 According to the second invention, by using the first crushed stone unit having a smaller horizontal projected area than the second crushed stone unit, the crushed stone unit can be arranged as close as possible to the outer periphery of the foundation where scouring is likely to occur. .. Further, the gap created by arranging the first crushed stone unit and the second crushed stone unit having different sizes can be closed by the third crushed stone unit. The third crushed stone unit can be expected to enhance the scouring prevention effect in the vicinity of the foundation where the risk of scouring is particularly high. It also works to prevent the movement and scattering of the first crushed stone unit, which has a small area and therefore a small weight.
本発明によれば、砕石ユニットを効率的に設置することができる洗掘防止構造および洗掘防止方法を提供することができる。 According to the present invention, it is possible to provide a scouring prevention structure and a scouring prevention method capable of efficiently installing a crushed stone unit.
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。
図１は洗掘防止構造３１の鉛直方向の断面を示す図である。図２は洗掘防止構造３１を上方から見た図であり、図１のＡ−Ａ線断面図である。図３は砕石ユニットの概要を示す図である。図４は図１に示す砕石ユニット９付近の拡大図である。
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a vertical cross section of the scouring prevention structure 31. FIG. 2 is a view of the scouring prevention structure 31 as viewed from above, and is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a diagram showing an outline of the crushed stone unit. FIG. 4 is an enlarged view of the vicinity of the crushed stone unit 9 shown in FIG.
図１、図２に示すように、洗掘防止構造３１は、水底の地盤３に設置された基礎であるモノパイル１の周囲に構築される。洗掘防止構造３１は、フィルター層５、第１の砕石ユニット７、第２の砕石ユニット９、第３の砕石ユニット１１等からなる。 As shown in FIGS. 1 and 2, the scouring prevention structure 31 is constructed around a monopile 1 which is a foundation installed on the ground 3 at the bottom of the water. The scouring prevention structure 31 includes a filter layer 5, a first crushed stone unit 7, a second crushed stone unit 9, a third crushed stone unit 11, and the like.
フィルター層５はモノパイル１の周囲の地盤３上に砕石を敷設して形成される。第１の砕石ユニット７は、フィルター層５上にモノパイル１の外周面に接するように配置される。第２の砕石ユニット９は、フィルター層５上の砕石ユニット７の外周側に平面視で略六角形状となるように並べて配置される。第３の砕石ユニット１１は、砕石ユニット７と砕石ユニット９との境界上に配置される。ケーブル３３は、砕石ユニット１１同士の間、砕石ユニット７と砕石ユニット９との間に通される。フィルター層５は、少なくとも砕石ユニット７および砕石ユニット９が設置される範囲に設置されればよい。 The filter layer 5 is formed by laying crushed stone on the ground 3 around the monopile 1. The first crushed stone unit 7 is arranged on the filter layer 5 so as to be in contact with the outer peripheral surface of the monopile 1. The second crushed stone unit 9 is arranged side by side on the outer peripheral side of the crushed stone unit 7 on the filter layer 5 so as to have a substantially hexagonal shape in a plan view. The third crushed stone unit 11 is arranged on the boundary between the crushed stone unit 7 and the crushed stone unit 9. The cable 33 is passed between the crushed stone units 11 and between the crushed stone unit 7 and the crushed stone unit 9. The filter layer 5 may be installed at least in a range where the crushed stone unit 7 and the crushed stone unit 9 are installed.
図３に示すように、砕石ユニット７、９、１１は、いずれもラッセル網等を用いた袋体２７に砕石類を充填し縫合したものである。砕石ユニット７、９、１１は、袋体の２７の底部であって、平面視の略中央付近に線材２９が接合される。線材２９は、波浪による袋体２７内での砕石類の移動を抑制し、砕石類の移動による袋体２７の摩耗を防止する。 As shown in FIG. 3, the crushed stone units 7, 9, and 11 are all made by filling a bag body 27 using a Russell net or the like with crushed stones and suturing them. The crushed stone units 7, 9 and 11 are the bottoms of 27 of the bag body, and the wire rod 29 is joined to the vicinity of substantially the center in a plan view. The wire rod 29 suppresses the movement of crushed stones in the bag body 27 due to waves, and prevents the bag body 27 from being worn due to the movement of the crushed stones.
砕石ユニット９、１１の袋体２７の容量は砕石ユニット７の袋体２７の容量よりも大きい。例えば、砕石ユニット９、１１の袋体２７内には８ｔの砕石類が充填され、砕石ユニット７の袋体２７内には４ｔの砕石類が充填される。平坦な場所に置かれた砕石ユニット７、９、１１は上方から見ると略円形であり、砕石ユニット９、１１の水平投影面積は砕石ユニット７の水平投影面積より大きい。 The capacity of the bag 27 of the crushed stone units 9 and 11 is larger than the capacity of the bag 27 of the crushed stone unit 7. For example, the bag 27 of the crushed stone units 9 and 11 is filled with 8 tons of crushed stones, and the bag 27 of the crushed stone unit 7 is filled with 4 tons of crushed stones. The crushed stone units 7, 9 and 11 placed on a flat place are substantially circular when viewed from above, and the horizontally projected area of the crushed stone units 9 and 11 is larger than the horizontally projected area of the crushed stone unit 7.
図４に示すように平坦な場所に置かれた砕石ユニット９の径Ｌ１と高さＨ１との比Ｌ１／Ｈ１は、砕石ユニット９が容易に変形可能である程度に大きい（例えば図に示す例では比が２．５以上）ものとする。砕石ユニット７、１１についても同様である。このような扁平な砕石ユニット７、９、１１を用いることにより、図４に示す砕石ユニット９の例のように、砕石ユニット７、９、１１を、隣接する他の砕石ユニット７、９、１１との間に隙間が生じないように重なり部分を設けて配置することができる。 As shown in FIG. 4, the ratio L1 / H1 of the diameter L1 and the height H1 of the crushed stone unit 9 placed on a flat place is large to some extent so that the crushed stone unit 9 can be easily deformed (for example, in the example shown in the figure). The ratio shall be 2.5 or more). The same applies to the crushed stone units 7 and 11. By using such flat crushed stone units 7, 9 and 11, the crushed stone units 7, 9 and 11 can be combined with other adjacent crushed stone units 7, 9 and 11 as in the example of the crushed stone unit 9 shown in FIG. An overlapping portion can be provided and arranged so that a gap does not occur between the two.
図５は、砕石ユニット９の設置範囲を示す図である。図５に示す例では、砕石ユニット９の平面視での設置範囲の外接円１５の径１９と内接円１７の径２１との平均値を径２３としたとき、径２３がモノパイル１の径１３の５倍である。ここで、外接円１５とは平面視で砕石ユニット９の設置範囲の全体を含む最小円であり、内接円１７とは砕石ユニット９の設置範囲に全体が含まれる最大円である。フィルター層５は、例えば、水が透過可能なアスファルトマット等で構成され、少なくとも砕石ユニット９および砕石ユニット１１が設置される範囲に形成される。 FIG. 5 is a diagram showing an installation range of the crushed stone unit 9. In the example shown in FIG. 5, when the average value of the diameter 19 of the circumscribed circle 15 and the diameter 21 of the inscribed circle 17 in the installation range of the crushed stone unit 9 in a plan view is the diameter 23, the diameter 23 is the diameter of the monopile 1. It is 5 times as much as 13. Here, the circumscribed circle 15 is the minimum circle including the entire installation range of the crushed stone unit 9 in a plan view, and the inscribed circle 17 is the maximum circle including the entire installation range of the crushed stone unit 9. The filter layer 5 is made of, for example, an asphalt mat that allows water to pass through, and is formed at least in a range in which the crushed stone unit 9 and the crushed stone unit 11 are installed.
次に、洗掘防止構造３１の構築方法について説明する。図６は砕石ユニット７、９を配置する工程を示す図である。 Next, a method of constructing the scouring prevention structure 31 will be described. FIG. 6 is a diagram showing a process of arranging the crushed stone units 7 and 9.
洗掘防止構造３１を構築するには、まず、モノパイル１の周囲の地盤３上にフィルター層５を形成する。また、フィルター層５の形成と前後して、モノパイル１からフィルター層５上に延伸するケーブル３３（図２）を配置する。その後、図６（ａ）に示すように、複数の砕石ユニット７をモノパイル１の外周面に接するように環状に並べて配置する。砕石ユニット７は、例えばクレーンで１個ずつ吊り下げて水底に配置されてもよいが、装置や治工具等を用いて複数個の砕石ユニット７を一括して設置してもよい。例えば、モノパイル１から離した状態で、モノパイル１に沿って、複数の砕石ユニット７を吊り降ろし、設置の際に、モノパイル１側に移動させて、砕石ユニット７をモノパイル１に接触するように配置してもよい。 In order to construct the scouring prevention structure 31, first, the filter layer 5 is formed on the ground 3 around the monopile 1. Further, before and after the formation of the filter layer 5, a cable 33 (FIG. 2) extending from the monopile 1 onto the filter layer 5 is arranged. After that, as shown in FIG. 6A, a plurality of crushed stone units 7 are arranged in an annular shape so as to be in contact with the outer peripheral surface of the monopile 1. The crushed stone unit 7 may be suspended one by one by a crane and arranged on the bottom of the water, or a plurality of crushed stone units 7 may be collectively installed by using a device, a jig or the like. For example, in a state of being separated from the monopile 1, a plurality of crushed stone units 7 are suspended along the monopile 1, moved to the monopile 1 side at the time of installation, and the crushed stone unit 7 is arranged so as to be in contact with the monopile 1. You may.
次に、図６（ｂ）に示すように、複数の砕石ユニット９を砕石ユニット７の外周に平面視で略六角形状となるように隙間なく並べて配置する。砕石ユニット７と砕石ユニット９とは寸法が異なるため、砕石ユニット７と砕石ユニット９との間には隙間が生じる。この隙間を塞ぐため、図２に示すように砕石ユニット１１を砕石ユニット７と砕石ユニット９との境界部に配置する。 Next, as shown in FIG. 6B, a plurality of crushed stone units 9 are arranged side by side on the outer periphery of the crushed stone unit 7 so as to have a substantially hexagonal shape in a plan view. Since the crushed stone unit 7 and the crushed stone unit 9 have different dimensions, a gap is formed between the crushed stone unit 7 and the crushed stone unit 9. In order to close this gap, the crushed stone unit 11 is arranged at the boundary between the crushed stone unit 7 and the crushed stone unit 9 as shown in FIG.
図７は設置用治具２５を示す図、図８は設置用治具２５ａを示す図である。砕石ユニット９は、鋼製の設置用治具２５、２５ａ等にフック（図示せず）を用いて複数個ずつ吊り下げて水底に配置される。 FIG. 7 is a diagram showing the installation jig 25, and FIG. 8 is a diagram showing the installation jig 25a. A plurality of crushed stone units 9 are suspended from steel installation jigs 25, 25a, etc. using hooks (not shown) and arranged on the bottom of the water.
設置用治具２５を用いて砕石ユニット９を設置する場合には、例えば、図７（ａ）に示すように、設置用治具２５に、複数の砕石ユニット９を、隣接する砕石ユニット９同士の高さを変えて、適切な重なりが得られるような間隔をおいて一列に吊り下げる。そして、水中に砕石ユニット９を沈下させて同時にフック（図示せず）を外す。これにより、図７（ｂ）に示すように複数の砕石ユニット９を重なり部分を設けて１列に配置することができる。 When the crushed stone unit 9 is installed using the installation jig 25, for example, as shown in FIG. 7A, a plurality of crushed stone units 9 are placed on the installation jig 25, and the adjacent crushed stone units 9 are connected to each other. Change the height of the jigs and hang them in a row at intervals so that proper overlap can be obtained. Then, the crushed stone unit 9 is subsided in water and the hook (not shown) is removed at the same time. As a result, as shown in FIG. 7B, a plurality of crushed stone units 9 can be arranged in one row with overlapping portions.
設置用治具２５ａを用いて砕石ユニット９を場合する際には、例えば、図８（ａ）に示すように、設置用治具２５ａに、複数の砕石ユニット９を、隣接する砕石ユニット９同士の高さを変えて、適切な重なりが得られるような間隔をおいて２列に吊り下げる。そして、水中に砕石ユニット９を沈下させて各列毎にフックを外す。これにより、図８（ｂ）に示すように複数の砕石ユニット９を重なり部分を設けて２列に配置することができる。 When the crushed stone unit 9 is used with the installation jig 25a, for example, as shown in FIG. 8A, a plurality of crushed stone units 9 are attached to the installation jig 25a, and the adjacent crushed stone units 9 are connected to each other. Change the height of the jigs and hang them in two rows at intervals so that an appropriate overlap can be obtained. Then, the crushed stone unit 9 is submerged in water and the hook is removed for each row. As a result, as shown in FIG. 8B, a plurality of crushed stone units 9 can be arranged in two rows with overlapping portions.
このように、本実施形態では、砕石ユニット９より水平投影面積の小さい砕石ユニット７を用いることにより、モノパイル１の外周付近に砕石ユニット７をなるべく隙間なく配置することができる。また、砕石ユニット７の外側に砕石ユニット９を平面視で略六角形状となるように重なり部分を設けて並べることにより、砕石ユニット９を確実に隙間なく配置することができる。さらに、砕石ユニット１１を配置することにより、大きさの異なる砕石ユニット７と砕石ユニット９とを並べることで生じた隙間を塞ぐことができる。これにより、砕石ユニット７、９を１層で構成して砕石ユニット７と砕石ユニット９との隙間を砕石ユニット１１で塞ぐだけの効率的な配置が実現され、石材の使用量の削減や工期の短縮が可能となる。 As described above, in the present embodiment, by using the crushed stone unit 7 having a smaller horizontal projection area than the crushed stone unit 9, the crushed stone unit 7 can be arranged as close as possible to the outer periphery of the monopile 1. Further, by arranging the crushed stone units 9 on the outside of the crushed stone unit 7 by providing overlapping portions so as to have a substantially hexagonal shape in a plan view, the crushed stone units 9 can be reliably arranged without gaps. Further, by arranging the crushed stone unit 11, it is possible to close the gap created by arranging the crushed stone unit 7 and the crushed stone unit 9 having different sizes. As a result, an efficient arrangement is realized in which the crushed stone units 7 and 9 are composed of one layer and the gap between the crushed stone unit 7 and the crushed stone unit 9 is closed by the crushed stone unit 11, reducing the amount of stone used and shortening the construction period. It can be shortened.
本実施形態では、砕石ユニット９の平面視での設置範囲の外接円１５の径１９と内接円１７の径２１との平均の径２３をモノパイル１の径１３の５倍とすることにより、洗掘防止効果を確保しつつ砕石ユニット９の設置範囲を縮小することができる。 In the present embodiment, the average diameter 23 of the diameter 19 of the circumscribed circle 15 and the diameter 21 of the inscribed circle 17 in the installation range of the crushed stone unit 9 in a plan view is set to 5 times the diameter 13 of the monopile 1. The installation range of the crushing stone unit 9 can be reduced while ensuring the scouring prevention effect.
但し、砕石ユニット９の平面視での設置範囲は上記した範囲に限らず、砕石ユニット９の平面視での設置範囲の外接円の径と内接円の径との平均の径２３がモノパイル１の径１３の３倍から５倍であればよい。図９は、砕石ユニット９の設置範囲をさらに縮小した例を示す図である。図９（ａ）は平均の径２３ａをモノパイル１の径１３の４倍とした例である。図９（ｂ）は平均の径２３ｂをモノパイル１の径１３の３倍とした例である。フィルター層は少なくとも砕石ユニット９および砕石ユニット１１が設置される範囲に形成されればよく、図９（ａ）（ｂ）に示す例ではフィルター層５ａ、５ｂは砕石ユニット９および砕石ユニット１１が設置される範囲より広い範囲に形成される。このように砕石ユニット９およびフィルター層の平面視での設置範囲をさらに縮小した場合でも洗掘防止効果を得ることができる。これら３〜５倍の範囲で洗掘防止工が機能することは、波浪を対象とした縮尺１／３０スケールの水理模型実験にて確認されている。 However, the installation range of the crushed stone unit 9 in a plan view is not limited to the above range, and the average diameter 23 of the diameter of the circumscribed circle and the diameter of the inscribed circle in the installation range of the crushed stone unit 9 in a plan view is monopile 1. It may be 3 to 5 times the diameter of 13. FIG. 9 is a diagram showing an example in which the installation range of the crushed stone unit 9 is further reduced. FIG. 9A is an example in which the average diameter 23a is four times the diameter 13 of the monopile 1. FIG. 9B is an example in which the average diameter 23b is three times the diameter 13 of the monopile 1. The filter layer may be formed at least within the range in which the crushed stone unit 9 and the crushed stone unit 11 are installed. In the example shown in FIGS. 9A and 9B, the filter layers 5a and 5b are provided with the crushed stone unit 9 and the crushed stone unit 11. It is formed in a wider range than it is. As described above, even when the installation range of the crushed stone unit 9 and the filter layer in a plan view is further reduced, the scouring prevention effect can be obtained. It has been confirmed in a 1/30 scale hydraulic model experiment for waves that the scouring prevention work works in the range of 3 to 5 times.
また、砕石ユニット９を水底に配置するための設置用治具は、上記したものに限らない。設置用治具に吊り下げる砕石ユニット９の列数、１列あたりの砕石ユニット９の数は、砕石ユニット９の配置計画に応じて決定すればよい。また、各砕石ユニット９の吊り下げ高さやフックを外すタイミングは、一部の砕石ユニット９のフックを外した時の設置用治具の位置ずれや回転を考慮して決定すればよい。 Further, the installation jig for arranging the crushed stone unit 9 on the bottom of the water is not limited to the above. The number of rows of crushed stone units 9 suspended from the installation jig and the number of crushed stone units 9 per row may be determined according to the arrangement plan of the crushed stone units 9. Further, the hanging height of each crushed stone unit 9 and the timing of removing the hook may be determined in consideration of the positional deviation and rotation of the installation jig when the hook of a part of the crushed stone unit 9 is removed.
さらに、フィルター層５の設置は必須ではない。図１０は、フィルター層の働きを内在した砕石ユニットを示す図である。図１０（ａ）に示す砕石ユニット１３ａは袋体２７の底にフィルター層程度の小さい粒径の石２８ａを入れたものであり、図１０（ｂ）に示す砕石ユニット１３ｂは、袋体２７の底にフィルター層と同程度の砂の目詰まりが見込める網状のシート２８ｂを敷いたものである。フィルター層５を設置しない場合は、図１０に示すような砕石ユニットを用いてもよい。 Further, the installation of the filter layer 5 is not essential. FIG. 10 is a diagram showing a crushed stone unit having an inherent function of a filter layer. The crushed stone unit 13a shown in FIG. 10 (a) is formed by putting a stone 28a having a particle size as small as that of a filter layer in the bottom of the bag body 27, and the crushed stone unit 13b shown in FIG. 10 (b) is the bag body 27. A net-like sheet 28b, which is expected to be clogged with sand to the same extent as the filter layer, is laid on the bottom. When the filter layer 5 is not installed, a crushed stone unit as shown in FIG. 10 may be used.
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.
例えば、水底の地盤に設置されたジャケット式基礎のアンカー杭などに本発明を適用してもよい。 For example, the present invention may be applied to an anchor pile of a jacket-type foundation installed on the ground of the bottom of the water.
１………モノパイル
３………地盤
５、５ａ、５ｂ………フィルター層
７、９、１１、１３ａ、１３ｂ………砕石ユニット
１９、２１、２３、２３ａ、２３ｂ………径
１５、１７………円
２５、２５ａ………設置用治具
２７………袋体
２８ａ………石
２８ｂ………シート
２９………線材
３１………洗掘防止構造
３３………ケーブル
1 ………… Monopile 3 ………… Ground 5, 5a, 5b ………… Filter layer 7, 9, 11, 13a, 13b ………… Crushed stone unit 19, 21, 23, 23a, 23b ………… Diameter 15, 17 ……… Circle 25, 25a ……… Installation jig 27 ………… Bag body 28a ………… Stone 28b ………… Sheet 29 ………… Wire rod 31 ………… Scour prevention structure 33 ………… Cable
Claims (8)
水底の地盤に設置された基礎の外周面に接するように環状に並べて配置された複数の第１の砕石ユニットと、
複数の前記第１の砕石ユニットの外周の全周に配置された、前記第１の砕石ユニットよりも水平投影面積の大きい複数の第２の砕石ユニットと、
前記第１の砕石ユニットと前記第２の砕石ユニットとの隙間を塞ぐように配置された、前記第１の砕石ユニットよりも水平投影面積の大きい第３の砕石ユニットと、
を具備することを特徴とする洗掘防止構造。 It is a scouring prevention structure that uses a crushed stone unit in which the bag is filled with crushed stones.
A plurality of first crushed stone units arranged in a ring shape so as to be in contact with the outer peripheral surface of the foundation installed on the ground of the bottom of the water.
A plurality of second crushed stone units having a larger horizontal projection area than the first crushed stone unit and arranged all around the outer circumference of the plurality of first crushed stone units.
A third crushed stone unit having a larger horizontal projection area than the first crushed stone unit and arranged so as to close the gap between the first crushed stone unit and the second crushed stone unit.
A scouring prevention structure characterized by being equipped with.
水底の地盤に設置された基礎の外周面に接するように環状に並べて複数の第１の砕石ユニットを配置する工程と、
複数の前記第１の砕石ユニットの外周の全周に、前記第１の砕石ユニットよりも水平投影面積の大きい複数の第２の砕石ユニットを配置する工程と、
前記第１の砕石ユニットと前記第２の砕石ユニットとの隙間を塞ぐように、前記第１の砕石ユニットよりも水平投影面積の大きい第３の砕石ユニットを配置する工程と、
を具備することを特徴とする洗掘防止方法。 It is a method of preventing scouring using a crushed stone unit in which the bag body is filled with stone.
The process of arranging a plurality of first crushed stone units in a ring shape so as to be in contact with the outer peripheral surface of the foundation installed on the ground of the water bottom, and
The entire circumference of the outer periphery of the plurality of the first crushed stone units, placing a large plurality of second lithotripsy units of horizontal projection area than the first crushed stone units,
A step of arranging a third crushed stone unit having a larger horizontal projection area than the first crushed stone unit so as to close the gap between the first crushed stone unit and the second crushed stone unit.
A method for preventing scouring, which is characterized by being provided with.
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| JP7333880B1 (en) * | 2023-03-09 | 2023-08-25 | 前田工繊株式会社 | Scouring prevention method for underwater structures |
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| JPH0921123A (en) * | 1995-07-06 | 1997-01-21 | Toyobo Co Ltd | Material for preventing scouring of underwater structure |
| US5762448A (en) * | 1996-05-29 | 1998-06-09 | Continuum Dynamics, Inc. | System for alleviating scouring around submerged structures |
| JPH1150428A (en) * | 1997-08-05 | 1999-02-23 | Seni Doboku Kaihatsu Kk | Net bag for foot protection |
| JP2955267B2 (en) * | 1998-02-25 | 1999-10-04 | 太陽工業株式会社 | Box-shaped bag-like body and manufacturing method thereof |
| JP3871925B2 (en) * | 2001-12-04 | 2007-01-24 | 株式会社テトラ | Backfill structure and backfill construction method |
| ES2468192T3 (en) * | 2009-12-29 | 2014-06-16 | Kyowa Co., Ltd. | Method to protect submarine cables and submarine long tubes |
| PT2354535E (en) * | 2009-12-29 | 2012-08-31 | Kyowa Co Ltd | Method for constructing a foundation for a wind power generation system |
| DK2956588T3 (en) * | 2013-02-18 | 2018-11-12 | Swan Net Gundry Ltd | EROSION REMOVAL AND REDUCTION DEVICE |
| JP7123709B2 (en) * | 2018-09-10 | 2022-08-23 | 鹿島建設株式会社 | Construction method of anti-scouring work around pile-shaped body and anti-scouring work around pile-shaped body |
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