Construction method

Abstract

To provide a construction method capable of shortening the construction period when driving a monopile by hoisting it together with two crane ships. [Solution] A construction method for hoisting and constructing a monopile MP using a first crane C1 owned by a first ship S1 and a second crane C2 owned by a second ship S2, characterized in that it includes a hoisting process in which the first crane C1 and the second crane C2 hoist the monopile MP together, a lifting process in which the first crane C1 lifts up one end of the monopile MP so that the pipe axis of the monopile MP is aligned in the vertical direction, and a driving process in which the second crane C2 places a hanging pile driver at one end and drives the monopile MP.

Description

[Technical field]

[0001] The present disclosure relates to an installation method. [Background technology]

[0002] Conventionally, a monopile has been hoisted together using two crane ships. Patent Document 1 discloses that a monopile-type steel pipe pile is hoisted together using a first crawler crane of a SEP for driving foundation piles and a second crawler crane of a SEP for transporting piles, that the monopile-type steel pipe pile is hoisted by the first crawler crane with its axis parallel to the vertical direction, and that driving of the monopile-type steel pipe pile is started by a pile driving device attached to the first crawler crane of the SEP for driving foundation piles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-37397 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the monopile steel pipe pile is hoisted by the first crawler crane with its axis parallel to the vertical direction, and then the same first crawler crane drives the monopile steel pipe pile with a pile driving device. Therefore, after the monopile steel pipe pile is hoisted with its axis parallel to the vertical direction, it is necessary to remove the first crawler crane from the monopile steel pipe pile and attach the pile driving device to the first crawler crane. Therefore, since the monopile steel pipe pile is kept on standby during this work, there is room for shortening the construction period.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a construction method that can shorten the construction period when driving a monopile by hoisting it together using two crane ships. [Means for solving the problem]

[0006] <1> The construction method according to aspect 1 of the present disclosure is a construction method for hoisting a monopile using a first crane owned by a first ship and a second crane owned by a second ship, and is characterized by comprising a hoisting process for hoisting the monopile using the first crane and the second crane, a lifting process for lifting one end of the monopile with the first crane so that the pipe axis of the monopile is aligned in the vertical direction, and a driving process for driving the monopile by the second crane placing a hoisting pile driver at one end of the monopile. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a construction method that can shorten the construction period when driving a monopile by hoisting it together using two crane ships. [Brief description of the drawings]

[0008] [Figure 1] FIG. 13 is a plan view of a hanging step according to the embodiment. [Diagram 2] FIG. 11 is a side view of a hanging step according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] 4 is a view taken along the arrow IV in FIG. 2. [Diagram 5] FIG. [Figure 6] FIG. 13 is a plan view of a removal step according to the embodiment. [Figure 7] FIG. 11 is a side view of a removal step according to the embodiment. [Figure 8] FIG. 11 is a side view of the erection process according to the embodiment. [Figure 9] FIG. 11 is a plan view of a guide step according to the embodiment. [Figure 10] FIG. 11 is a side view of a guide step according to the embodiment. [Figure 11] FIG. 11 is a side view of a temporary driving step according to the embodiment. [Figure 12] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a construction method according to an embodiment of the present disclosure will be described with reference to the drawings. The construction method according to this embodiment is a construction method for driving a monopile into seabed ground. The monopile is, for example, a steel pipe for supporting an offshore wind turbine (not shown) by being connected to the lower end of the offshore wind turbine. The monopile is connected to the lower end of the offshore wind turbine via, for example, a transition piece (not shown). That is, the monopile supports the offshore wind turbine via, for example, the transition piece. Alternatively, the monopile may be connected directly to the lower end of the offshore wind turbine without the transition piece. That is, the monopile may support the offshore wind turbine without the transition piece. The monopile is, for example, a tubular member. In the following, in this embodiment, the monopile is described as being a cylindrical member. Alternatively, the monopile is not limited to this, and may be, for example, a rectangular tubular member. In accordance with this, each configuration described later may be appropriately adapted.

[0010] FIG. 1 is a plan view of a hanging step according to an embodiment. FIG. 2 is a side view of the hanging step according to the embodiment. FIG. 3 is a cross-sectional view taken along line III-III of FIG. FIG. 4 is a view taken along the arrow IV in FIG. In this embodiment, as shown in FIG. 1, a first ship S1 and a second ship S2 are used to construct the monopile MP. The first ship S1 is a ship with lifting capacity. That is, the first ship S1 is, for example, a crane ship (floating crane) such as a fixed crane ship or a slewing crane ship. The second ship S2 is, for example, a slewing crane ship. In this embodiment, a crane ship refers to a ship equipped with a crane. A fixed crane ship refers to a ship equipped with a crane whose crane cannot rotate. A slewing crane ship refers to a ship equipped with a crane whose crane can rotate. As shown in FIG. 1, the first ship S1 has a first crane C1. The second ship S2 has a second crane C2. In this embodiment, the first crane C1 may or may not be rotatable. In this embodiment, the second crane C2 is rotatable. In this embodiment, when driving the monopile MP into the seabed with a hammer, two cranes are used as shown in FIGS. 1 to 4. That is, for example, as shown in Fig. 2, a monopile MP is constructed by hoisting together a first crane C1 of a first ship S1 and a second crane C2 of a second ship S2. This makes it possible to handle relatively large monopiles MP. In this embodiment, the lifting load of the first crane C1 is equal to or greater than the lifting load of the second crane C2. Furthermore, when the monopile MP is hoisted by the first crane C1 and the second crane C2, it is preferable to keep the distance between the first crane C1 and the second crane C2, i.e., the distance between the first ship S1 and the second ship S2, constant so that the monopile MP can be hoisted stably. For this reason, it is preferable to dispose a barge B between the first ship S1 and the second ship S2 as shown in Fig. 1. Disposing the barge B between the first ship S1 and the second ship S2 in this manner is particularly suitable when, for example, the length of the monopile MP is relatively long.

[0011] In this embodiment, as shown in Figures 2 and 3, one end of the monopile MP is hoisted by a first crane C1. Also, as shown in Figures 2 and 4, the other end of the monopile MP is hoisted by a second crane C2. More specifically, the first crane C1 hoists one end of the monopile MP by hoisting a gripping tool BH that grips one end of the monopile MP. Also, the second crane C2 hoists the other end of the monopile MP by hoisting a suspension frame HF that supports the vicinity of the other end of the monopile MP. In this embodiment, the vicinity of the other end of the monopile MP refers to, for example, a region that is 20% of the length of the monopile MP from the other end of the monopile MP. In this case, when the monopile MP is suspended, the bending moment acting on the monopile MP can be suppressed. Alternatively, the vicinity of the other end of the monopile MP may be a region that is 10% of the length of the monopile MP from the other end of the monopile MP. In this case, when the monopile MP is hoisted by the first ship S1 and the second ship S2, the monopile MP can be stably hoisted by the first ship S1 and the second ship S2. The gripping tool BH and the suspension frame HF will be described in detail below.

[0012] (Regarding gripping tools) The gripping tool BH is attached to one end of the monopile MP. The gripping tool BH is suspended by the first crane C1. As shown in Fig. 2, the gripping tool BH has a gripping part BHa that grips one end of the monopile MP by clamping it from the outside. The gripping tool BH is attached to one end of the monopile MP by the gripping part BHa. In this embodiment, the gripping tool BH is a known vibro hammer. The gripping tool BH, which is a vibro hammer, vibrates one end of the monopile MP, causing the other end of the monopile MP to penetrate into the seabed. That is, the gripping tool BH is first used to connect one end of the monopile MP to the wire of the first crane C1 while the monopile MP is suspended by the first crane C1 and the second crane C2. Then, after the monopile MP is erected on the sea, the gripping tool BH vibrates one end of the monopile MP. This causes the other end of the monopile MP to penetrate into the seabed.

[0013] (About the hanging stand) FIG. 5 is an enlarged view of the suspension frame HF. The suspension frame HF is attached near the other end of the monopile MP as shown in FIG. 2. The suspension frame HF is suspended by the second crane C2 as shown in FIG. 4. As shown in FIG. 5, the suspension frame HF has a substantially U-shaped cross section. In this embodiment, the substantially U-shaped shape refers to a shape having a bottom portion extending in an arbitrary direction and side portions extending from both ends of the bottom portion in a direction intersecting the arbitrary direction. As shown in FIG. 5, the suspension frame HF has a bottom portion HFa and a side portion HFb. The bottom portion HFa and the side portion HFb of the suspension frame HF form an opening HFc. As shown in FIG. 5, a shackle Sh is provided at each end of the side portion HFb that is not connected to the bottom portion HFab. A wire of the second crane C2 is connected to the shackle Sh. The suspension frame HF accommodates the other end vicinity of the monopile MP inside an opening HFc formed by the bottom part HFa and the side part HFb. At this time, the suspension frame HF only supports the weight of the monopile MP by abutting against the monopile MP, and is not fixed by bolts or welding. With the other end vicinity of the monopile MP accommodated in the opening HFc, the suspension frame HF is lifted by the second crane C2. In this way, the other end vicinity of the monopile MP is lifted by the second crane C2 and the suspension frame HF.

[0014] (About the lid) In this embodiment, a cover MPC is provided at the other end of the monopile MP as shown in Fig. 5. This prevents water from entering the monopile MP when one end of the monopile MP is hoisted by the first crane C1, thereby generating buoyancy in the monopile MP. This reduces the weight added to the first crane C1 when hoisting one end of the monopile MP. It also makes it easier to carry out the removal process described below.

[0015] The lid MPC is, for example, disk-shaped and in contact with the inner circumferential surface of the cylindrical monopile MP. The outer diameter of the lid MPC is smaller than the inner circumferential circle of the monopile MP. This allows the lid MPC to be disposed so as to fit inside the monopile MP. A sealing mechanism (not shown) that can be expanded or contracted by, for example, hydraulic or pneumatic pressure is provided on the outer peripheral edge of the lid MPC. For example, with the lid MPC placed inside the monopile MP, the sealing mechanism is brought into close contact with the inside of the monopile MP by hydraulic or pneumatic pressure. In other words, the sealing mechanism is pressed against the inner peripheral surface of the monopile MP. This fixes the lid MPC and the monopile MP while preventing water from entering the inside of the monopile MP. Also, for example, with the lid MPC and the monopile MP fixed, the hydraulic or pneumatic pressure of the sealing mechanism is lowered to remove the lid MPC from the monopile MP. The sealing mechanism of the lid MPC is preferably operated, for example, by remote control, which, for example, makes it unnecessary for an operator to directly remove the lid MPC.

[0016] (Construction method) The construction method of the monopile MP according to this embodiment will be described below. The construction method of the monopile MP according to this embodiment includes a hoisting process, a removal process, a lifting process, and a driving process. Each of these processes is carried out after the monopile MP is transported to the construction site by a carrier ship S3, for example, as shown in Figure 1.

[0017] (About the hanging process) The hoisting process is a process in which the monopile MP is hoisted by the first crane C1 and the second crane C2. More specifically, in the hoisting process, as shown in Fig. 1 and Fig. 2, the first crane C1 hoists the holding tool BH that holds one end of the monopile MP, and the second crane C2 hoists the hoisting frame HF that supports the vicinity of the other end of the monopile MP. In this way, the monopile MP is hoisted from the carrier S3 in a lying state. After the monopile MP is hoisted from the carrier S3, the carrier S3 is moved, making it possible to move the other end of the monopile MP downward.

[0018] As described above, when hoisting the monopile MP, it is preferable to keep the distance between the first crane C1 and the second crane C2, i.e., the distance between the first ship S1 and the second ship S2, constant. For this reason, the hoisting process includes an arrangement process for adjusting the distance between the first ship S1 and the second ship S2. In the arrangement step, before the monopile MP is hoisted, as shown in Figs. 1 and 2, the first ship S1 and the second ship S2 are arranged to sandwich the barge B so that the distance between the first hook C1f of the first crane C1 and the second hook C2f of the second crane C2 is approximately equal to the length of the monopile MP. The distance between the first hook C1f and the second hook C2f is, for example, the distance between the first hook C1f and the second hook C2f in the horizontal direction. Alternatively, the distance between the first hook C1f and the second hook C2f may be the distance when the first hook C1f and the second hook C2f are at the same height in the up-down direction (vertical direction). The distance between the first hook C1f and the second hook C2f is the distance when the first crane C1 and the second crane C2 are both slewing cranes, and when either or both of them are slewing cranes, the distance between the first hook C1f and the second hook C2f is the distance when either or both of them are in the initial position in the slewing direction. In this embodiment, "approximately the same" means that the error in the distance or length between them is within about 5%. That is, in the placement process, the distance between the first hook C1f of the first crane C1 and the second hook C2f of the second crane C2 is adjusted to be at least within ±5% of the length of the monopile MP. Here, depending on the size of the barge B to be placed between the first ship S1 and the second ship S2, the distance between the first ship S1 and the second ship S2, i.e., the distance between the first hook C1f of the first crane C1 and the second hook C2f of the second crane C2, may not be appropriate. In such a case, a spacer (not shown) may be appropriately placed between the first ship S1 and the second ship S2 and the barge B. Alternatively, a fender (not shown) may be placed between the first ship S1 and the second ship S2 and the barge B.

[0019] (About the removal process) FIG. 6 is a plan view of a removing step according to the embodiment. FIG. 7 is a side view of a removing step according to the embodiment. The removal process is a process in which the second crane C2 lowers the suspension frame HF, thereby automatically removing the suspension frame HF from the vicinity of the other end of the monopile MP. When performing the removal process, the carrier ship S3 is not positioned below the monopile MP, as shown in Figures 6 and 7. In the removal process, first, the suspension frame HF is lowered by the second crane C2, thereby submerging the suspension frame HF and the vicinity of the other end of the monopile MP supported by the suspension frame HF in water. As described above, the cover MPC is provided at the other end of the monopile MP. The suspension frame HF only supports the weight of the monopile MP by contacting the monopile MP, and is not fixed by bolts, welding, or the like. Therefore, when the other end of the monopile MP sinks in the water due to the suspension frame HF, buoyancy is generated near the other end of the monopile MP. As a result, the other end of the monopile MP no longer needs to be supported by the suspension frame HF, and so it automatically separates from the suspension frame HF. This allows the removal process to be carried out.

[0020] After the removal process, the second crane C2 is used for the driving process, which will be described later. Therefore, it is preferable that the second crane C2 performs an operation of changing the object to be lifted from the lifting rack HF to the pile driver IH while the first crane C1 performs the lifting process, which will be described next.

[0021] (About the lifting process) The lifting process is a process in which one end of the monopile MP is lifted by the first crane C1 so that the tube axis of the monopile MP is aligned vertically. In this way, the monopile MP is erected on the sea. The lifting process includes an erecting process, a guiding process, a temporary driving process, and a removal process.

[0022] FIG. 8 is a side view of the erecting step according to the embodiment. The erection process is a process of erecting the monopile MP on the sea by lifting one end of the monopile MP with a first crane C1, as shown in Fig. 8. This makes it possible to drive the monopile MP into the seabed. In addition, when the monopile MP is erected and is in a nearly vertical state, the hydraulic or air pressure of the sealing mechanism of the cover MPC may be lowered to remove the cover MPC from the monopile MP. This allows water to enter the inside of the monopile MP, making it easier for the other end of the monopile MP to sink toward the seabed. Also, in the temporary driving process and driving process described below, it is easier for the other end of the monopile MP to penetrate into the seabed ground. In addition, a rope may be attached to the cover MPC in advance before the erecting process to make it easier to pull the removed cover MPC out to sea.

[0023] FIG. 9 is a plan view of a guide step according to the embodiment. FIG. 10 is a side view of the guide step according to the embodiment. The guiding process is a process of aligning the monopile MP with the installation location on the seabed as shown in Figures 9 and 10. Specifically, the guiding process is a process of guiding the monopile MP to a positioning marine structure G that has been installed on the ocean in advance. The positioning marine structure G is placed on the ocean in advance in accordance with the installation location of the monopile MP. The positioning marine structure G is formed, for example, by appropriately combining steel pipes as shown in Fig. 9 and Fig. 10. The positioning marine structure G is formed, for example, in a U-shape in plan view as shown in Fig. 9. In the guiding process, the monopile MP erected in the erecting process is appropriately aligned so that the monopile MP enters the opening Ga of the positioning marine structure G, thereby allowing the positioning marine structure G to guide the monopile MP. In addition to the function of guiding the monopile MP, the positioning marine structure G may also have a function of supporting the monopile MP before it is installed on the seabed, for example.

[0024] FIG. 11 is a side view of the temporary driving step according to the embodiment. The temporary driving process is a process of penetrating the other end of the monopile MP into the seabed. Here, when the guiding process is completed, a gripping tool BH is attached to one end of the monopile MP as shown in FIG. 11. As described above, the gripping tool BH is a vibro hammer. In the temporary driving process, while the first crane C1 is lifting the monopile MP via the gripping tool BH, the gripping tool BH, which is a vibro hammer, is vibrated. This causes the other end of the monopile MP to penetrate into the seabed. In the temporary driving process, for example, it is preferable to penetrate the other end of the monopile MP toward the seabed to such an extent that the monopile MP can stand on the seabed by itself.

[0025] The removal process is a process of removing the first crane C1 from one end of the monopile MP. That is, in the removing step, the gripping tool BH is removed from one end of the monopile MP by removing the gripping part BHa, thereby removing anything that may hinder the driving step described next.

[0026] (About the driving process) FIG. 12 is a side view of the driving step. The driving step is a step in which the second crane C2 places the pile driver IH at one end and drives the monopile MP. In this embodiment, the pile driver IH is an impact hammer, such as a so-called hydraulic impact hammer. That is, the pile driver IH drops a weight to strike one end of the monopile MP downward, thereby driving the monopile MP into the seabed. The construction of the monopile MP according to this embodiment is carried out through each of the above steps.

[0027] As described above, the construction method according to the present embodiment includes a hoisting process, a lifting process, and a driving process. More specifically, first, in the hoisting process, the first crane C1 and the second crane C2 hoist the monopile MP together. Next, in the lifting process, the first crane C1 lifts one end of the monopile MP so that the tube axis of the monopile MP is aligned vertically. Then, in the driving process, the second crane C2 places the hoisting pile driver IH at one end and drives the monopile MP. That is, after the hoisting process is performed by the first crane C1 and the second crane C2, the lifting process is performed by the first crane C1 without using the second crane C2. This allows preparations for the driving process, such as placing the pile driver IH on the second crane C2, to be made while the hoisting process is being performed by the first crane C1. Therefore, the time required for switching between the hoisting process and the driving process can be shortened. Therefore, the construction period can be shortened.

[0028] In the hoisting process, the gripping tool BH that grips one end of the monopile MP is hoisted by the first crane C1, and the suspension frame HF that supports the vicinity of the other end of the monopile MP is hoisted by the second crane C2. The suspension frame HF has a substantially U-shaped cross section. Since the suspension frame HF has a substantially U-shaped cross section, when the suspension frame HF supports the vicinity of the other end of the monopile MP, the vicinity of the other end of the monopile MP can be stabilized only by placing the vicinity of the other end of the monopile MP on the suspension frame HF without fixing by bolt fastening or the like. In addition, for example, when the vicinity of the other end of the monopile MP is submerged in water and buoyancy occurs, the suspension frame HF is automatically detached from the vicinity of the other end of the monopile MP without performing any special work. Therefore, for example, it is possible to eliminate the need to perform the work of removing the suspension frame HF from the vicinity of the other end of the monopile MP by a diver or the like. Furthermore, while the first crane C1 is performing the lifting process, the second crane C2 can quickly switch from the lifting frame HF to the pile driver IH, thereby shortening the construction period.

[0029] When the construction method according to this embodiment is carried out in the open sea, it may be difficult to maintain a constant distance between the first ship S1 and the second ship S2 due to high waves. Therefore, the mutual hoisting process includes an arrangement process. In the arrangement process, the first ship S1 and the second ship S2 are arranged to sandwich the barge B so that the distance between the first hook C1f of the first crane C1 and the second hook C2f of the second crane C2 is approximately equal to the length of the monopile MP. By sandwiching the barge B between the first ship S1 and the second ship S2 in this manner, it is possible to easily maintain the distance between the first ship S1 and the second ship S2.

[0030] The method further includes a removal process. In the removal process, the second crane C2 lowers the suspension frame HF, thereby automatically removing the suspension frame HF from the vicinity of the other end of the monopile MP. By automatically removing the suspension frame HF from the vicinity of the other end of the monopile MP in this way, it is possible to eliminate the need for a diver or the like to remove the suspension frame HF from the vicinity of the other end of the monopile MP. Furthermore, while the first crane C1 is performing the lifting process, the second crane C2 can quickly replace the suspension frame HF with the pile driver IH. This makes it possible to shorten the construction period.

[0031] The lifting process also includes a removal process. In the removal process, the first crane C1 is removed from one end of the monopile MP. This makes it possible to remove any object that may hinder the driving process from one end of the monopile MP when the driving process is carried out. This makes it easier for the second crane C2 of the second ship S2 to drive one end of the monopile MP using the hanging pile driver IH in the driving process. This makes it possible to make the construction work more efficient, which contributes to shortening the construction period.

[0032] The lifting process also includes a guiding process. In the guiding process, the positioning marine structure G guides the monopile MP. This makes it easy to position the monopile MP so that its pipe axis is aligned in the vertical direction. In the driving process, the second crane C2 of the second ship S2 can easily drive one end of the monopile MP using the hanging pile driver IH. This makes it possible to make the construction work more efficient, which can contribute to shortening the construction period.

[0033] In addition, the second ship S2 is a slewing crane ship. This allows the second crane C2 to easily align the position of the second hook C2f with respect to the object to be lifted. In other words, the second crane C2 can easily position the hoisting pile driver IH at one end of the monopile MP. In addition, for example, when the second crane C2 is replacing the object to be lifted by the hoisting frame HF with the pile driver IH, the second crane C2 can easily approach the pile driver IH. This makes it possible to make the construction work more efficient. This can therefore contribute to shortening the construction period.

[0034] In addition, a cover MPC is provided at the other end of the monopile MP. This can prevent water from entering the inside of the monopile MP. Therefore, when lifting one end of the monopile MP with the first crane C1, buoyancy can be generated in the monopile MP by submerging the other end of the monopile MP in water. Therefore, for example, even if the lifting capacity of the first crane C1 is low compared to the weight of the monopile MP, it is possible to lift one end of the monopile MP.

[0035] The technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure. For example, the first ship S1 and the second ship S2 are not limited to the above-mentioned crane ship, and may be a SEP (Self-Elevating Platform).

[0036] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described modified examples may be combined as appropriate.

[0037] (Additional Note) The construction method according to the embodiment can be understood, for example, as follows. <1> A construction method according to one embodiment of the present disclosure is a construction method for hoisting a monopile using a first crane owned by a first ship and a second crane owned by a second ship, and is characterized by comprising a hoisting process in which the monopile is hoisted by the first crane and the second crane, a lifting process in which the first crane lifts one end of the monopile so that the pipe axis of the monopile is aligned in the vertical direction, and a driving process in which the second crane positions a hanging pile driver at one end of the monopile and drives the monopile.

[0038] According to the above construction method, the construction method includes a mutual hoisting process, a lifting process, and a driving process. More specifically, first, in the mutual hoisting process, the monopile is mutually hoisted by the first crane and the second crane. Next, in the lifting process, one end of the monopile is lifted by the first crane so that the pipe axis of the monopile is aligned vertically. Then, in the driving process, the second crane places a hoisting pile driver at one end and drives the monopile. That is, after the mutual hoisting process is performed by the first crane and the second crane, the lifting process is performed by the first crane without using the second crane. In this way, while the lifting process is being performed by the first crane, preparations for the driving process, such as placing a pile driver on the second crane, can be made. Therefore, the time required for switching between the lifting process and the driving process can be shortened. Therefore, the construction period can be shortened.

[0039] <2> the above <1> In the construction method according to the present invention, the hoisting process may be characterized in that a holding device that holds one end of the monopile is hoisted by the first crane, and a hoisting stand having an approximately U-shaped cross section that supports the vicinity of the other end of the monopile is hoisted by the second crane.

[0040] In the mutual hoisting process, a gripping tool for gripping one end of the monopile is hoisted by a first crane, and a suspension frame for supporting the vicinity of the other end of the monopile is hoisted by a second crane. The suspension frame has a substantially U-shaped cross section. Since the suspension frame has a substantially U-shaped cross section, when the suspension frame supports the vicinity of the other end of the monopile, the vicinity of the other end of the monopile can be stabilized only by placing the vicinity of the other end of the monopile on the suspension frame without fixing by bolt fastening or the like. In addition, this allows the suspension frame to automatically detach from the vicinity of the other end of the monopile without performing any special work, for example, when the vicinity of the other end of the monopile sinks in water and buoyancy is generated. Therefore, for example, it is possible to eliminate the need to perform the work of removing the suspension frame from the vicinity of the other end of the monopile by a diver or the like. Furthermore, while the first crane is performing the lifting process, the second crane can quickly switch from the lifting rack to the pile driver, thereby shortening the construction period.

[0041] <3> the above <1> or <2> In the construction method according to the above, a configuration may be adopted in which the hoisting process includes a positioning process of positioning the first ship and the second ship so as to sandwich the barge in between, so that the distance between the first hook of the first crane and the second hook of the second crane is approximately equal to the length of the monopile.

[0042] Here, when the construction method according to this embodiment is carried out in the open sea, it may be difficult to maintain a constant distance between the first ship and the second ship due to high waves. Therefore, the hoisting process includes an arrangement process. In the arrangement process, the first ship and the second ship are arranged so as to sandwich the barge, so that the distance between the first hook of the first crane and the second hook of the second crane is approximately equal to the length of the monopile. By sandwiching the barge between the first ship and the second ship in this way, it is possible to easily maintain the distance between the first ship and the second ship.

[0043] <4> the above <1> from <3> In the construction method according to any one of the above aspects, a configuration may be adopted that further includes a removal process of automatically removing the suspension frame from near the other end by lowering the suspension frame with the second crane.

[0044] The method further includes a removal process. In the removal process, the second crane lowers the suspension frame, thereby automatically removing the suspension frame from the vicinity of the other end of the monopile. By automatically removing the suspension frame from the vicinity of the other end of the monopile in this manner, it is possible to eliminate the need for a diver or the like to remove the suspension frame from the vicinity of the other end of the monopile. Furthermore, while the first crane is performing the lifting process, the second crane can quickly replace the suspension frame with the pile driver. This makes it possible to shorten the construction period.

[0045] <5> the above <1> from <4> In the construction method according to any one of the above aspects, a configuration may be adopted in which the lifting step includes a removal step of removing the first crane from the one end.

[0046] The lifting process also includes a removal process. In the removal process, the first crane is removed from one end of the monopile. This makes it possible to remove any object that may hinder the driving process from one end of the monopile when the driving process is carried out. This makes it easier for the second crane of the second ship to drive one end of the monopile with the hanging pile driver in the driving process. This makes it possible to make the construction work more efficient, which can contribute to shortening the construction period.

[0047] <6> the above <1> from <5> In the construction method according to any one of the above aspects, a configuration may be adopted in which the lifting step includes a guiding step of guiding the monopile to a positioning marine structure.

[0048] The lifting step also includes a guiding step. In the guiding step, the monopile is guided by the positioning marine structure. This makes it easier to position the monopile so that its pipe axis is aligned in the vertical direction. In the driving step, the second crane of the second ship can easily drive one end of the monopile using a hanging pile driver. This makes it possible to make the construction work more efficient, which can contribute to shortening the construction period.

[0049] <7> the above <1> from <6> In the construction method according to any one of the above aspects, a configuration may be adopted in which the second ship is a revolving crane ship.

[0050] In addition, the second ship is a slewing crane ship. This allows the second crane to easily align the position of the second hook with respect to the object to be hoisted. In other words, the second crane can easily position the hoisting pile driver at one end of the monopile. In addition, for example, when the second crane is replacing the object to be hoisted by the second crane from the hoisting stand to the pile driver, the second crane can easily approach the pile driver. This makes it possible to make the construction work more efficient. This can therefore contribute to shortening the construction period.

[0051] <8> the above <1> from <7> In the construction method according to any one of the above aspects, a configuration may be adopted in which a lid is provided on the other end of the monopile.

[0052] In addition, a lid is provided on the other end of the monopile, which makes it possible to prevent water from entering the inside of the monopile. Therefore, when lifting one end of the monopile with the first crane, buoyancy can be generated in the monopile by submerging the other end of the monopile in water. Therefore, for example, even if the lifting capacity of the first crane is low compared to the weight of the monopile, it is possible to lift one end of the monopile. [Explanation of symbols]

[0053] B Barge BH gripper BHa gripping part C1 First crane C1f 1st hook C2 Second crane C2f 2nd hook G. Offshore structure for positioning Ga aperture HF Hanging Mount HFa bottom HFb Side HFc opening IH pile driver MP Monopile MPC lid S1 1st ship S2 2nd ship S3 Carrier Sh Shackle

Claims

1. A construction method for constructing monopiles by hoisting them together using a first crane owned by a first ship and a second crane owned by a second ship, comprising the steps of: a hoisting process of hoisting the monopile with the first crane and the second crane; a lifting process of lifting one end of the monopile with the first crane so that a pipe axis of the monopile is aligned in a vertical direction; a removing step of removing the second crane from near the other end of the monopile; a driving step in which the second crane places a pile driver at one end of the monopile and drives the monopile; Equipped with the second vessel is a floating crane; A construction method characterized by the above.

2. A construction method for constructing monopiles by hoisting them together using a first crane owned by a first ship and a second crane owned by a second ship, comprising the steps of: a hoisting process of hoisting the monopile with the first crane and the second crane; a lifting process of lifting one end of the monopile with the first crane so that a pipe axis of the monopile is aligned in a vertical direction; a removing step of removing the second crane from near the other end of the monopile; a driving step in which the second crane places a pile driver at one end of the monopile and drives the monopile; Equipped with The first crane and the second crane are cranes of a fixed crane ship or a slewing crane ship; A construction method characterized by the above.

3. A construction method for constructing monopiles by hoisting them together using a first crane owned by a first ship and a second crane owned by a second ship, comprising the steps of: a hoisting process of hoisting the monopile with the first crane and the second crane; a lifting process of lifting one end of the monopile with the first crane so that a pipe axis of the monopile is aligned in a vertical direction; a removing step of removing the second crane from near the other end of the monopile; a driving step in which the second crane places a pile driver at one end of the monopile and drives the monopile; Equipped with In the hoisting step, a gripping tool that grips one end of the monopile is hoisted by the first crane, The gripping tool is a vibro hammer. A construction method characterized by the above.

4. In the hoisting process, a gripping tool that grips one end of the monopile is hoisted by the first crane, and a hoisting stand having a substantially U-shaped cross section that supports the vicinity of the other end of the monopile is hoisted by the second crane.

2. The construction method according to claim 1 .

5. the hoisting step includes a positioning step of positioning the first ship and the second ship so as to sandwich the barge between them, so that a distance between a first hook of the first crane and a second hook of the second crane is approximately equal to a length of the monopile.

5. The construction method according to claim 4.

6. A construction method for constructing monopiles by hoisting them together using a first crane owned by a first ship and a second crane owned by a second ship, comprising the steps of: a hoisting process of hoisting the monopile with the first crane and the second crane; a lifting process of lifting one end of the monopile with the first crane so that a pipe axis of the monopile is aligned in a vertical direction; a driving step in which the second crane places a pile driver at one end of the monopile and drives the monopile; Equipped with In the hoisting process, a gripping tool that grips one end of the monopile is hoisted by the first crane, and a hoisting stand having a substantially U-shaped cross section that supports the vicinity of the other end of the monopile is hoisted by the second crane. a removal process of automatically removing the suspension frame from the vicinity of the other end by lowering the suspension frame with the second crane; Further comprising: A construction method characterized by the above.

7. the lifting step includes a removing step of removing the first crane from the one end; The removing step is performed after the tube axis of the monopile is aligned along the vertical direction.

2. The construction method according to claim 1 .

8. The lifting step includes a guiding step of guiding the monopile to a positioning marine structure. The construction method according to any one of claims 1 to 7.

9. The second vessel is a slewing vessel. The construction method according to any one of claims 1 to 7.

10. A lid is provided on the other end of the monopile. The construction method according to any one of claims 1 to 7.

11. The hoisting process includes a positioning process of positioning the first vessel and the second vessel so as to sandwich the barge. The construction method according to any one of claims 1 to 7.

12. The method further includes a transporting step of transporting the monopile to a construction site by a transport ship. The construction method according to any one of claims 1 to 7.

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