Method for installing a floating offshore wind power plant

Abstract

The application provides a floating offshore wind power equipment construction method, the wind power equipment comprises a wind power unit and a floating foundation, the construction method comprises the following steps: separately constructing the wind power unit; segmentally constructing and segmentally splicing the floating foundation, the floating foundation is divided into four parts of a heaving plate, a column, a cross brace and a deck, the heaving plate is assembled first, the column and the cross brace are assembled on the heaving plate by taking the heaving plate as a general assembly basis, the deck is separately constructed while the column and the cross brace are assembled, the deck is hoisted as a whole on the column and the cross brace after the heaving plate, the column and the cross brace are assembled, and the general assembly of the whole floating foundation is completed; the assembled floating foundation is separately towed to an assembling sea area close to a wharf and fixed in the assembling sea area, a tower drum assembly is hoisted section by section on the floating foundation, the wind power unit is fixedly installed at a preset position of the tower drum assembly, and the floating foundation with the wind power unit fixed thereon is towed to a target sea area. The application has high construction efficiency, high construction precision and safe construction environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of offshore wind power equipment, in particular to a floating offshore wind power equipment construction method. BACKGROUND

[0002] Wind energy has a very high utilization value as a clean and renewable energy source. Offshore wind power equipment is a key device for utilizing wind energy at sea. Offshore wind power equipment includes fixed wind power equipment and floating wind power equipment. In a sea area with a water depth greater than 50 meters, considering economic cost and other factors, floating offshore wind power equipment is generally used. The fixed floating equipment is a fixed wind turbine, and the installation environment is relatively stable and safe. The wind turbine of the floating offshore wind power equipment needs to be in a floating state. Due to the complex offshore environment, how to efficiently, accurately and safely build the floating offshore wind power equipment is of great significance to the efficient operation of offshore wind power equipment. SUMMARY

[0003] The purpose of the present application is to provide a floating offshore wind power equipment construction method, which solves the problems of low construction efficiency, low construction precision and unsafe construction environment of the existing floating offshore wind power equipment.

[0004] A floating offshore wind power equipment construction method is provided, the wind power equipment includes a wind turbine and a floating foundation, and the construction method includes:

[0005] The wind turbine is separately constructed;

[0006] The floating foundation is constructed and spliced in sections, the floating foundation is divided into a heave plate, a column, a cross brace and a deck, the heave plate, the column and the deck are all constructed in sections, the heave plate is first constructed in sections, the column and the cross brace are assembled on the heave plate, and the deck is separately constructed while the column and the cross brace are assembled, after the heave plate, the column and the cross brace are assembled, the deck is integrally hoisted above the column, and the assembly of the floating foundation is completed;

[0007] The assembled floating foundation is separately towed to an assembly sea area close to a wharf and temporarily fixed in the assembly sea area, a tower assembly is hoisted on the floating foundation section by section, the wind turbine is fixedly installed at a preset position of the tower assembly, and the floating foundation with the wind turbine fixed thereon is towed to a target sea area.

[0008] In an embodiment, the heave plate is first constructed in sections, the column and the cross brace are assembled on the heave plate, and the deck is separately constructed while the column and the cross brace are assembled, including:

[0009] The transfer lines of the plurality of ballast tanks in the heaving plate are taken as the segmentation lines, each heaving plate is divided into four heaving plate segments along the segmentation lines, and the four heaving plate segments that are built are assembled into the heaving plate; each column is divided into three column segments from top to bottom according to the empty tank area, the three column segments are built respectively, and then the three column segments are assembled to the heaving plate; the deck is divided into three independent areas and one common area, each independent area is a deck segment, and the common area is a deck segment, and the deck is built according to four deck segments.

[0010] In an embodiment, the tower section assembly is hoisted on the floating foundation section by section, comprising:

[0011] The tower section assembly is split into a plurality of tower sections;

[0012] The first tower section is hoisted first, and the hoisting method of the first tower section is as follows: a guide wind rope is installed on the bottom flange of the first tower section, and the first tower section is hoisted on the floating foundation by pulling the guide wind rope;

[0013] According to the hoisting method of the first tower section, the second tower section, the third tower section, and the fourth tower section and above are sequentially hoisted on the previous tower section from bottom to top.

[0014] In an embodiment, the tower section assembly is hoisted on the floating foundation section by section, further comprising:

[0015] During the hoisting of the tower section assembly, the draft and the levelness of the floating foundation are dynamically adjusted by synchronously adjusting the ballast water levels of the plurality of ballast tanks in the floating foundation, and the draft of the floating foundation is adjusted to a first predetermined depth after the hoisting of the tower section assembly is completed.

[0016] In an embodiment, the wind turbine includes a nacelle and a rotor, and the step of installing the nacelle includes:

[0017] During the hoisting of the tower section assembly, the nacelle is hoisted to above the top of the top tower section, the nacelle is slowly moved, and when the nacelle is located directly above the top tower section, the nacelle is slowly lowered until all the bolts below the nacelle are inserted into the bolt holes of the preset tower section.

[0018] During the installation of the nacelle, the draft and the levelness of the floating foundation are dynamically adjusted by synchronously adjusting the ballast water levels of the plurality of ballast tanks in the floating foundation, and the draft of the floating foundation is adjusted to a second predetermined depth after the hoisting of the nacelle is completed.

[0019] In an embodiment, the rotor is installed after the installation of the nacelle, and the installation steps of the rotor are as follows:

[0020] The impeller comprises a hub and three blades, the impeller is formed by sequentially assembling a first blade, a second blade and a third blade to the hub, two impeller hangers are arranged on the impeller, a lifting point is arranged at a preset distance from a blade root of the first blade, and a wind rope sleeve is arranged on a blade tip of each of the second blade and the third blade;

[0021] One end of the first lifting belt is connected to the main crane, the other end of the first lifting belt is connected to the impeller hanger, one end of the second lifting belt is connected to the auxiliary crane, the other end of the second lifting belt is fixedly connected to the lifting point through the blade guard, and two guide ropes pass through the wind rope sleeves on the blade tips of the second blade and the third blade;

[0022] The first lifting belt and the second lifting belt are simultaneously lifted, and the direction of the impeller is controlled through the guide ropes, in the lifting process, the second blade and the third blade are always kept upward, the first blade is always kept downward, the lifting speed of the first blade is slower than that of the second blade and the third blade, until the impeller is hung vertically, and then the wind turbine is slowly lifted through the circular lifting belt, and the wind turbine is fixedly installed on the cabin.

[0023] In an embodiment, the lifting point is located on the axis of the first blade, and a preset tool is installed on the axis at a preset distance from the blade root.

[0024] In an embodiment, after the impeller is hung to the vertical position, the flat lifting belt connected to the first blade and the blade guard are disassembled, and the auxiliary crane is removed.

[0025] In an embodiment, after the wind turbine is fixedly installed on the cabin, the levelness of the floating foundation is dynamically adjusted, and the draft of the floating foundation is adjusted to a third predetermined depth.

[0026] The floating offshore wind power equipment construction method has the following beneficial effects:

[0027] 1. According to the structural characteristics of the floating offshore wind power equipment, the manufacturing efficiency is improved, the manufacturing precision and convenience are ensured, the selection requirement of large-scale construction equipment is reduced, the construction safety is improved, and the construction cost is reduced by separately manufacturing each component of the wind turbine, segmentally constructing and assembling the floating foundation, and separately towing each component for monomer towing construction.

[0028] 2. After the floating foundation is constructed, it is separately towed to a designated site, and then the wind turbine is assembled, and then the floating foundation is integrally towed, thereby reducing the integrally towing distance and reducing the risk. Before the wind turbine is lifted, the floating foundation is in a shallow draft state on the sea, thereby reducing the towing cost. When the wind turbine is installed, the floating foundation is in a deep draft state, thereby indirectly reducing the lifting height of the wind turbine and the lifting height of the crawler crane, and reducing the installation cost. BRIEF DESCRIPTION OF DRAWINGS

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of a floating foundation according to an embodiment of this application;

[0031] Figure 2 This is a schematic diagram illustrating a stand-alone towed floating foundation according to an embodiment of this application;

[0032] Figure 3 This is a schematic diagram illustrating a floating foundation that is individually fixed in the assembly area according to an embodiment of this application;

[0033] Figure 4 This is a schematic diagram illustrating a stand-alone wind turbine unit according to an embodiment of this application;

[0034] Figure 5 This is a structural schematic diagram of a tower assembly that is hoisted section by section according to an embodiment of this application;

[0035] Figure 6 This is a schematic diagram illustrating a segmented structure of a heave plate according to an embodiment of this application;

[0036] Figure 7 This is a schematic diagram illustrating a segmented column structure according to an embodiment of this application;

[0037] Figure 8 This is a schematic diagram illustrating a deck segment structure according to an embodiment of this application;

[0038] Figure 9 This is a schematic diagram of a cross brace segment structure according to an embodiment of this application.

[0039] 10. Dock; 20. Assembly area; 100. Wind turbine; 110. Rotor; 111. Hub; 112. Blade; 200. Floating foundation; 210. Heave plate; 211. First heave plate segment; 212. Second heave plate segment; 213. Third heave plate segment; 214. Fourth heave plate segment; 220. Column; 221. First column segment; 222. Second column segment; 223. Third column segment; 230. Cross brace; 240. Deck; 241. First independent area; 242. Second independent area; 243. Third independent area; 244. Public area; 300. Tower assembly. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0042] The present application provides a floating offshore wind power equipment construction method, which includes a wind power unit and a floating foundation, as shown in Figures 1-5 The construction method specifically includes the following steps:

[0043] The wind power unit 100 is separately built, specifically, the hub and the blades are separately manufactured in respective production workshops, and after the manufacturing is completed, the wind power unit is transported to the wharf by a transport barge, and according to the assembly sequence and the assembly process, the wind power unit is assembled on the wharf side field.

[0044] The floating foundation 200 is separately built and separately assembled, as shown in Figure 1 The floating foundation is divided into four parts, i.e., a heave plate 210, a column 220, a cross brace 230 and a deck 240. The heave plate 210, the column 220 and the deck 240 are separately manufactured, the heave plate 210 is first separately assembled, the heave plate 210 is used as the general assembly basis, the column segments and the cross brace segments are assembled on the heave plate 210, the deck 240 is separately built while the column 220 and the cross brace 230 are assembled, after the heave plate 210, the column 220 and the cross brace 230 are assembled, the deck 240 is integrally hoisted above the column, and the general assembly of the floating foundation 200 is completed;

[0045] The general assembly of the floating foundation is separately towed to the assembly sea area 20 close to the wharf 10 and temporarily fixed in the assembly sea area 20, specifically, after the floating foundation is towed to the assembly sea area 20, in an example, the floating foundation is fixed with the wharf by a cable through the wharf equipment or the foundation own winch device (as shown in Figure 3 Then, as shown in Figure 5The tower drum assembly 300 is hoisted section by section on the floating foundation 200, the wind turbine 100 is fixedly installed at the preset position of the tower drum assembly 300 in the process of hoisting the tower drum assembly section by section, and then the floating foundation 200 fixedly installed with the wind turbine 100 is towed to the target sea area. By fixing the floating foundation in the assembly sea area first, the fixed installation of the tower drum assembly, the wind turbine and the floating foundation in the safe environment (the shore site of the wharf) is realized.

[0046] The floating foundation construction implementation method is a huge and complex system engineering, and the construction period is usually long, and the space and crane resources are required. In the above implementation process, the wind turbine components are manufactured separately, the floating foundation is constructed and assembled in sections, and the tower drum assembly is hoisted in sections, the floating foundation is separately towed to the designated site after the construction of the floating foundation is completed, then the wind turbine assembly operation is performed, and then the integrated towing is performed, that is, the segmented construction is combined with the single-body towing, the construction efficiency is improved, the weight of the single towing is reduced, and the risk is reduced. And by the single-body towing and the hoisting of the tower drum assembly in sections, the wind turbine is installed in the process of installing the tower drum assembly, the hoisting height of the wind turbine is reduced, the hoisting equipment selection range is increased, and the cost is reduced. The floating offshore wind power equipment construction method provided in the application improves the manufacturing efficiency, ensures the manufacturing precision and convenience, reduces the selection requirement of large-scale construction equipment, improves the construction safety, and reduces the construction cost.

[0047] In an embodiment, in order to further shorten the construction period, the heaving plate is assembled first, the heaving plate is used as the general assembly foundation, the column sections and the cross braces are assembled on the heaving plate, and the deck is separately constructed while the column sections and the cross braces are assembled, including:

[0048] Meanwhile, according to the lifting capacity of the crane in the construction site, each part of the floating foundation is segmented and manufactured. For details, see Figures 6-9The plurality of ballast tanks in the heave plate 210 are segmented by the intersection line of the heave plate, which is the demarcation line for segmented construction. Each heave plate 210 is divided into four heave plate segments (a first heave plate segment 211, a second heave plate segment 212, a third heave plate segment 213, and a fourth heave plate segment 214) along the segmented line. The four heave plate segments are assembled into the heave plate 210 after being constructed. Each column 220 is divided into three column segments (a first column segment 221, a second column segment 222, and a third column segment 223) from top to bottom according to the empty tank area. The three column segments are first constructed separately and then assembled to the heave plate 210. The deck 240 is divided into three independent areas (a first independent area 241, a second independent area 242, and a third independent area 243) and one common area 244. Each independent area is a deck segment, and the common area is a deck segment. The deck 240 is constructed according to the four deck segments. Each cross brace 230 is a whole, and there are three cross braces 230. The four parts of the floating foundation are constructed in the form of segments, which can be constructed simultaneously, improving the construction efficiency. In addition, the segmented combination of the structure of the floating foundation ensures the water tightness of the floating foundation, and realizes high-efficiency and high-precision construction.

[0049] In an embodiment, the tower section assembly is hoisted on the floating foundation section by section, comprising:

[0050] The tower section assembly 300 is divided into multiple tower sections;

[0051] The first tower section is hoisted first. The hoisting method of the first tower section is as follows: a guide wind rope is installed on the bottom flange of the first tower section, and the first tower section is hoisted on the floating foundation 200 by pulling the guide wind rope;

[0052] According to the hoisting method of the first tower section, the second tower section, the third tower section, the fourth tower section, and the tower sections above are hoisted on the previous tower section from bottom to top.

[0053] In the above embodiment, by dividing the tower section assembly into multiple sections, the single hoisting weight can be reduced, and the hoisting safety can be improved.

[0054] In an embodiment, the tower section assembly is hoisted on the floating foundation section by section, further comprising:

[0055] During the process of hoisting the tower section assembly 300 section by section, the draft and levelness of the floating foundation 200 are dynamically adjusted by adjusting the ballast water level of the plurality of ballast tanks in the floating foundation 200, and the draft of the floating foundation 200 is adjusted to a first predetermined depth after the hoisting of the tower section assembly 300 is completed. By reserving ballast tank rooms in the floating foundation 200 and adjusting the ballast during the whole installation process, the operation conditions of the floating installation of the wind turbine generator are met, and the installation of the wind turbine generator in the relative motion state of the floating foundation is realized. By adjusting the draft state, the eccentricity of the floating foundation + tower is dynamically adjusted, the hoisting height of the tower and the wind turbine generator is stabilized, and the safety of the hoisting operation is ensured.

[0056] In an embodiment, the wind turbine generator comprises a nacelle and a blade, and the step of installing the nacelle comprises:

[0057] During the process of hoisting the tower section assembly 300 section by section, the nacelle is hoisted to above the top of the top section of the tower section assembly 300, the nacelle is slowly moved, and when the nacelle is located directly above the fourth section of the tower section assembly 300, the nacelle is slowly lowered until all the bolts below the nacelle pass through the bolt holes of the fourth section of the tower section assembly 300. During the installation of the nacelle, the draft and levelness of the floating foundation are dynamically adjusted by synchronously adjusting the ballast water level of the plurality of ballast tanks in the floating foundation, and the draft of the floating foundation is adjusted to a second predetermined depth after the hoisting of the nacelle is completed.

[0058] In an embodiment, the blade is installed after the installation of the nacelle, and the installation steps of the blade are as follows:

[0059] Referring to Figure 4 The blade 110 comprises a hub 111 and three blades 112 (a first blade, a second blade and a third blade). Two blade hangers are arranged on the blade 110, a lifting point is arranged at a predetermined distance from the blade root of the first blade, in an embodiment, the lifting point is located at a predetermined position on the blade axis of the first blade, and a wind rope sleeve is arranged on the tip of the second blade and the third blade; the wind rope sleeve is installed in advance on the transport ship.

[0060] One end of a first lifting belt (two 120Tx9m circular lifting belts) is connected to the main crane, and the other end is connected to the blade hanger through two 150T arch-shaped shackles, respectively. At the same time, one end of a second lifting belt (one 30t x 15m x 300mm flat lifting belt) is connected to the auxiliary crane, the other end of the flat lifting belt is fixedly connected to the lifting point through the blade guard plate, and two guide ropes are passed through the wind rope sleeves on the tips of the second blade and the third blade.

[0061] Lifting the impeller 110, the impeller 110 is cleaned with clean non-fiber cloth and special cleaning agent before the hub 111 and the installation flange surface and threaded hole on the gearbox are connected with the nacelle. The circular sling and flat sling are lifted, and since the wind rope sleeve and guide rope need to be removed after the impeller is lifted, the sling should not be pulled too hard so that it can be easily removed from the ground after the impeller is installed. During lifting, the second and third blades are always kept on the top, the first blade is on the bottom, and the first blade rises slower than the second and third blades. The whole process keeps the blades away from the ground until the impeller is lifted vertically, and then the impeller is fixed and installed on the nacelle by slowly lifting the impeller through the circular sling. During the whole process, the direction of the impeller 110 is controlled by the guide rope so that it does not sway due to changes in wind direction.

[0062] In one embodiment, after the impeller is lifted to the vertical position, the flat sling and blade guard connected to the first blade are removed, and the auxiliary crane is removed. After the wind turbine is fixed and installed, the levelness of the floating foundation is dynamically adjusted, and the draft of the floating foundation is adjusted to a third predetermined depth, at which the draft of the floating foundation is suitable for towing.

[0063] In the above implementation process, the tower section assembly is lifted, the ballast compartment of the floating foundation is dynamically adjusted during lifting, the nacelle is lifted when the draft of the floating foundation reaches the specified depth, the nacelle is installed and fixed as the driving device for driving the impeller during the lifting of the tower section assembly, and the floating foundation is connected with the impeller while the compartment of the floating foundation is dynamically adjusted. The impeller is pre-assembled and then lifted. The installation process of the wind turbine (nacelle and impeller) is a relative motion state, and after the three blades and the hub are assembled into an impeller on the ground, the whole is lifted to the nacelle on the top of the tower, reducing the high-altitude operation link, improving the operation efficiency, and ensuring the safety of the lifting operation. At the same time, the motion state of the blade is controlled during lifting to realize safe and stable lifting to the floating foundation.

[0064] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of constructing a floating offshore wind power plant, c h a r a c t e r i s e d in that The wind power equipment comprises a wind power unit and a floating foundation, and the construction method comprises: The wind power unit is separately constructed; The floating foundation is separately constructed and spliced, and the floating foundation is divided into four parts, i.e., a heave plate, a column, a cross brace and a deck, wherein the heave plate, the column and the deck are separately constructed, the heave plate is first separately constructed, the column and the cross brace are assembled on the heave plate, the deck is separately constructed while the column and the cross brace are assembled, the deck is integrally hoisted above the column after the heave plate, the column and the cross brace are assembled, and the floating foundation is completely assembled; The completely assembled floating foundation is separately towed to an assembling sea area close to a wharf and temporarily fixed in the assembling sea area, a tower drum assembly is hoisted on the floating foundation section by section, the wind power unit is fixedly installed at a preset position of the tower drum assembly, and the floating foundation with the wind power unit fixed thereon is towed to a target sea area; The heave plate is first separately constructed, the column and the cross brace are assembled on the heave plate, and the deck is separately constructed while the column and the cross brace are assembled, and the method comprises: The heave plate is divided into four heave plate segments along the joint lines of the plurality of ballast tanks in the heave plate, the four heave plate segments are spliced to form the heave plate, each column is divided into three column segments from top to bottom according to the empty tank area, the three column segments are separately constructed, and then the three column segments are assembled on the heave plate, and the deck is divided into three independent regions and one common region, each independent region is a deck segment, and the common region is a deck segment, and the deck is constructed according to the four deck segments; The wind power unit comprises a cabin and a wheel, and the step of installing the cabin comprises: During the hoisting of the tower drum assembly section by section, the cabin is hoisted to above the top of the top section tower drum, the cabin is slowly moved, and when the cabin is directly above the top section tower drum, the cabin is slowly lowered until all the bolts below the cabin are inserted into the bolt holes of the preset section tower drum; During the installation of the cabin, the draft and the levelness of the floating foundation are dynamically adjusted by synchronously adjusting the water levels of the plurality of ballast tanks in the floating foundation, and after the hoisting of the cabin is completed, the draft of the floating foundation is adjusted to a second predetermined depth; The wheel comprises a hub and three blades, the first blade, the second blade and the third blade are sequentially assembled on the hub to form the wheel, two wheel lifting seats are arranged on the wheel, a lifting point is arranged at a distance of a preset distance from a blade root of the first blade, and a wind rope sleeve is arranged on the blade tip of each of the second blade and the third blade; One end of the first lifting belt is connected to the main hoist, the other end of the first lifting belt is connected to the wheel lifting seat, one end of the second lifting belt is connected to the auxiliary hoist, the other end of the second lifting belt is fixedly connected to the lifting point through the blade guard plate, and two guide ropes pass through the wind rope sleeves of the blade tips of the second blade and the third blade; The first lifting belt and the second lifting belt are simultaneously lifted, and the direction of the wheel is controlled through the guide ropes, during the lifting process, the second blade and the third blade are always above, the first blade is always below, the lifting speed of the first blade is slower than that of the second blade and the third blade, until the wheel is lifted to a vertical state, and then the wheel is slowly lifted through the circular lifting belt to be fixedly installed on the cabin.

2. The floating offshore wind power plant construction method according to claim 1, characterized in that, The tower section assembly is hoisted on the floating foundation section by section, comprising: The tower section assembly is split into multiple tower sections; The first tower section is hoisted first, and the hoisting method of the first tower section is as follows: a guide wind rope is installed on the bottom flange of the first tower section, and the first tower section is hoisted on the floating foundation by pulling the guide wind rope; The second tower section, the third tower section, and the fourth tower section and the tower sections above the fourth tower section are hoisted on the previous tower section from bottom to top according to the hoisting method of the first tower section.

3. The floating offshore wind power plant construction method according to claim 1, characterized in that, The tower section assembly is hoisted on the floating foundation section by section, comprising: During the hoisting of the tower section assembly, the draft and the levelness of the floating foundation are dynamically adjusted by synchronously adjusting the ballast water levels of multiple ballast tanks in the floating foundation, and the draft of the floating foundation is adjusted to a first predetermined depth after the hoisting of the tower section assembly is completed.

4. The floating offshore wind power plant construction method according to claim 1, characterized in that, The lifting point is located on the axis of the first blade and a preset tool is installed at a preset distance from the blade root along the axis.

5. The floating offshore wind power plant construction method according to claim 1, characterized in that, After the impeller is hoisted to the vertical position, the flat lifting belt and the blade guard connected to the first blade are disassembled, and the auxiliary crane is removed.

6. The floating offshore wind power plant construction method according to claim 1, characterized in that, After the wind turbine is fixedly installed, the levelness of the floating foundation is dynamically adjusted and the draft of the floating foundation is adjusted to a third predetermined depth.

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