Offshore single-pile structure foundation and construction method thereof

Abstract

The invention discloses an offshore single-pile structure foundation and a construction method thereof, the offshore single-pile structure foundation is composed of a main pile, a suction barrel assembly and a grouting sealing cover, the outer part of the main pile is annularly sleeved with the suction barrel assembly, and the top of the suction barrel assembly is provided with the grouting sealing cover. The structural form that the variable-diameter single pile and the multi-subdivision annular suction barrel are combined is adopted, the advantages of extremely high vertical bearing of the single pile and horizontal reinforcing supporting of the suction barrel are fully played, the horizontal swing load resisting capacity of the single pile on the mud surface section is effectively improved, and the horizontal swing load resisting capacity of the single pile on the mud surface section is effectively improved through horizontal reinforcing of the external suction barrel structure. Meanwhile, the structural rigidity is improved, the stability is improved, and long-term use is stable and reliable; the independent center supporting sleeve is arranged in the middle of the suction barrel assembly, so that when a single pile is scoured, the inner ring of the suction barrel can avoid a scouring pit, self-sinking sealing is achieved without being affected, the suction barrel can smoothly sink to the designed depth, and the bearing requirement is met.

Description

Technical Field

[0001] The invention relates to the technical field of marine engineering construction, and in particular to an offshore single pile structure foundation and a construction method thereof. Background Art

[0002] With the expansion of offshore wind power development and the complexity of environmental conditions, conventional offshore wind turbine foundations such as single pile foundations and jacket foundations can no longer fully adapt to the future development of offshore wind power, especially for special geological conditions with thick surface silt or hard soil at a depth of more than 40m. It is difficult to meet the upper load support needs with a single pile structure alone. Due to the weak support force of the surface silt, the horizontal load of the structure is difficult to meet. If the method of increasing the diameter of a single pile is adopted, high requirements will be placed on the piling equipment. If the pile diameter exceeds 10m, the current ship machinery equipment is basically unable to carry out construction. If the driving depth is increased, the rock embedding method needs to be adopted, and the construction difficulty and cost will be greatly increased. The investment in offshore wind power development is limited. How to make a fixed foundation, especially a wind turbine foundation, in sea areas with thick surface silt or shallow hard soil is a difficult problem that needs to be solved. For the currently used structure of a combination of a single pile and a suction cylinder, the gap between the inner ring of the suction cylinder and the outer wall of the single pile is small. The single pile is significantly scoured in the marine environment, resulting in scour pits around it. This will prevent the inner ring of the annular suction cylinder from completely contacting the mud surface to form an initial seal, and the suction cylinder cannot be sunk.

[0003] In order to solve the above problems, we propose an offshore monopile structure foundation and a construction method thereof. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides an offshore single pile structure foundation and a construction method thereof. The present invention provides the following technical solutions: An offshore single pile structure foundation, comprising a main pile and a suction cylinder assembly, wherein the main pile is a round tube formed by rolling a steel plate, the suction cylinder assembly is sleeved on the outside of the main pile, and a grouting cover is installed on the top of the suction cylinder assembly; The main pile is composed of an upper pipe pile, a diameter-changing section, and a lower pipe pile from top to bottom, and a top flange is coaxially welded on the top of the upper pipe pile; The suction cylinder assembly is a steel plate rolled and welded into a circular ring-shaped structure with an open bottom, a hollow middle and compartments around. The suction cylinder assembly consists of an annular suction cylinder assembly, a reinforcing support, an intermediate support sleeve, an inner straightening boss, a vertical guide pulley and a grouting isolation ring. According to the number of circumferential compartments, 6 to 8 groups of the annular suction cylinder assemblies are selected to form the main body of the annular structure. The annular structure main body formed by the annular suction cylinder assembly is coaxially welded with the intermediate support sleeve. The outer circumference of the intermediate support sleeve is arranged with the reinforcing supports that are consistent with the number of compartments. The vertical surface of the reinforcing support is welded to the outer side of the intermediate support sleeve. The top of the reinforcing support is tightly attached to the lower end of the upper ring plate of the intermediate support sleeve. The inner hole circumference of the intermediate support sleeve is welded with multiple sets of inner straightening bosses and vertical guide pulleys. The lower end of the intermediate support sleeve is flush with the cabin top plate of the annular suction cylinder assembly and is bonded and fixed with the grouting isolation ring. The grouting cover is an arc-shaped ring plate steel sheet structure, the main body of which is an arc-shaped ring plate cut and processed by steel plate. Four groups of hanging points are welded on the upper end of the ring plate, and 2 to 3 circles of reinforcing vertical ribs are welded on the inner side of the ring at the lower end of the ring plate.

[0005] Preferably, the annular suction cylinder assembly is a structural member with an arc-shaped bottom open formed by a partition plate, a cabin roof plate, an outer ring plate cut and rolled into an arc, and an inner ring plate; a trapezoidal pull-out reinforcement elbow plate is vertically welded to the outside of the outer ring plate, and an inverted cone-shaped scour protection cover made of steel plate is concentrically welded to the top of the outer side of the outer ring plate, and the scour protection cover is provided with a pull-out reinforcement elbow plate at the partition plate, and axial and radial bulkhead reinforcement plates and partition plate reinforcement elbow plates are welded to the inside of the compartment structure of the annular suction cylinder assembly and the lower part of the cabin roof plate, and support elbow plates are arranged at the corresponding axes of the pull-out reinforcement elbow plates and the bulkhead reinforcement plates, and an annular support elbow plate is welded to the inner ring plate in the radial direction.

[0006] Preferably, the inner straightening boss is a vertical plate with an angled lower end formed by cutting from a steel plate.

[0007] Preferably, the grouting isolation ring is a ring made of rubber material with a tapered lower end and a flat upper end, and the outer ring of the grouting isolation ring is tightly attached to the hole of the intermediate support sleeve.

[0008] Preferably, the anti-pullout reinforcement bracket is axially aligned with the compartment plate, and the lower part is a barb-shaped protrusion.

[0009] Preferably, an annulus cover plate with holes is welded on the upper part of the annulus support bracket.

[0010] The present invention also relates to a construction method for an offshore monopile structure foundation, the construction method comprising the following steps: Step S1: transport the offshore monopile structure foundation to the offshore construction site, the transport ship is close to the crane ship, and the steel pile is hoisted and erected according to the monopile construction method. The pile is placed in the required installation position, lowered into the mud by its own weight, and then a pile hammer is used to drive the pile until it is driven to the designed depth. After the steel pile is completed, it is necessary to check whether there are any external structures such as hanging points that affect the insertion of the suction cylinder assembly, and the suction cylinder is installed after cutting; Step S2: hoist and install the equipment for sinking and penetration onto the upper equipment installation base of the annular suction cylinder assembly, ensure the connection between the sinking and penetration equipment and the suction cylinder assembly, the hoisting personnel go to the internal platform on the top of the main pile, then hoist the suction cylinder assembly with the sinking and penetration equipment to the top of the main pile as a whole, adjust the structure to align, and slowly lower it so that the annular support bracket guides the suction cylinder assembly to gradually align with the main pile and gradually lower it. At the same time, the personnel on the internal platform on the top of the main pile direct the crane to adjust so that the end of the main pile is gradually inserted into the middle support sleeve, control the hoisting swing amplitude so that the grouting isolation ring passes through the top flange, and then slowly lower it to the vertical guide pulley in the middle support sleeve to stick to the outside of the upper pipe pile, and gradually lower it. At the same time, control the position of the suction cylinder assembly within the required range, and the crane ship continues to hook down so that the lower part of the suction cylinder assembly contacts the mud surface and slowly sinks, so that the structure enters the mud by its own weight. Before entering the mud, if the sinking and penetration equipment needs to be tested in water, it can also be temporarily stopped during hoisting, and continue to be lowered after debugging is completed; Step S3: Start the penetration equipment to penetrate, check the airtightness of each compartment one by one, if there are scouring pits in some compartments that affect the sealing, use upper pressure weights or penetrate other compartments to drive them to deepen the mud depth to form a seal, if the closure cannot be achieved through penetration, necessary mud and sand can be backfilled into the inner area of ​​the inner ring plate to form a sealed area; after all compartments are sealed, suction cylinder penetration is carried out to maintain the overall horizontal penetration, and if it is uneven, the penetration of the compartment with faster penetration (low point) is suspended, and the slower (high point) compartment is penetrated, and the horizontality is adjusted to not more than 3‰, and it is gradually adjusted, and the penetration negative pressure allowed by the design at different depths is controlled until the penetration reaches the bottom of the cabin top plate and is close to the mud surface. At this time, the current of the water pump motor of the penetration equipment is close to zero, and the penetration is completed. The penetration equipment is hoisted and recovered, and then the valves on the pipeline are closed or the plugging device is installed to complete the suction cylinder assembly penetration construction; Step S4: connect the grouting pipeline on the suction cylinder assembly, operate the grouting equipment on the water surface to penetrate the low-strength cement slurry of less than 5MPa into the gap in the suction cylinder assembly, discharge the water in the cabin, and ensure the long-term stability of the structure. If the penetration depth has reached the cabin top plate close to the mud surface, there is no need to grout the cylinder; after the grouting in the cylinder is completed, close the relevant valves to seal it and recycle the grouting pipeline; Step S5: clean the grouting equipment of the deck, refill with high-strength cement slurry greater than 70MPa, insert the pipeline into the annulus between the middle support sleeve and the lower pipe pile, put the pipe end close to the grouting isolation ring, and inject slurry to drain the seawater in the annulus; underwater divers check the grouting situation and stabilize the grouting pipeline to prevent it from falling out of the annulus; when the annulus grouting approaches the top of the middle support sleeve, the grouting cover of the deck is hoisted to cover the top of the annulus, leaving a grouting cover, and after the grouting is flush with the end of the middle support sleeve, the last grouting cover is covered to form a complete ring, and the vertical reinforcement is inserted into the cement slurry for fixing, so that the overall structural stability is more reliable. After the grouting is completed, the equipment is recovered, the construction is completed, and the ship and machinery are withdrawn and demobilized.

[0011] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. By adopting a structural form combining a variable diameter single pile with a multi-compartment annular suction cylinder, the advantages of the single pile's extremely strong vertical bearing capacity and the suction cylinder's horizontal reinforcement support are fully utilized, effectively improving the ability of the single pile in the mud surface section to resist horizontal swing loads; 2. The horizontal direction of the external suction bucket structure is strengthened to reduce the depth of a single pile into the mud, while improving the structural rigidity and stability, making it stable and reliable for long-term use; 3. By separating a separate central support sleeve in the middle of the suction cylinder assembly, the inner ring of the suction cylinder can avoid the scouring pit when the single pile is scoured, and the self-sinking seal is achieved without being affected, and the cylinder can be sunk to the designed depth smoothly to meet the bearing requirements; 4. By making a tic-tac-toe reinforcement plate inside the suction tube, the structure between the compartments is also strengthened to meet higher negative pressure penetration; 5. By setting an anti-pulling bracket on the outside of the cylinder, the anti-pulling capacity of one side of the structure when it is subjected to horizontal load is improved; 6. By setting a packer at the lower end of the central support sleeve, grouting can be done directly without annular dredging. The high-strength cement slurry can realize the reliable transfer of horizontal loads, and the construction is efficient. It can well solve the construction difficulties of the fixed monopile foundation on the shallow seabed and has good economy. 7. By setting a scour protection cover on the outside of the annular suction cylinder, water scour can be effectively reduced and the long-term stability of the suction cylinder foundation can be protected. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings: Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the main pile composition of a preferred embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of the suction cylinder of a preferred embodiment of the present invention; Figure 4 is a side view of the suction cylinder structure of a preferred embodiment of the present invention; Figure 5 This is a bottom view of the suction cylinder structure of a preferred embodiment of the present invention; Figure 6 This is a schematic diagram of the single-cabin structure of a suction cylinder according to a preferred embodiment of the present invention; Figure 7 It is a schematic diagram of the grouting capping structure of a preferred embodiment of the present invention.

[0013] in, Figure 1-7 The corresponding relationship between the reference numerals and the components is as follows: 1. Main pile; 11. Lower pipe pile; 12. Variable diameter section; 13. Upper pipe pile; 14. Top flange; 2. Suction cylinder assembly; 21. Annular suction cylinder assembly; 21. Annular suction cylinder assembly; 21. Subdivision plate; 212. Outer ring plate; 213. Pull-out reinforcement bracket; 214. Scour protection cover; 215. Support bracket; 216. Bulkhead reinforcement plate; 217. Subdivision plate reinforcement bracket; 218. Cabin top plate; 219. Annular cover plate; 2110. Annular support bracket; 2111. Inner ring plate; 22. Strengthening support; 23. Intermediate support sleeve; 24. Inner straightening boss; 25. Vertical guide pulley; 26. Grouting isolation ring; 3. Grouting cover; 31. Ring plate; 32. Lifting point; 33. Strengthening vertical reinforcement. Implementation

[0014] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0015] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0016] Combine the following Figure 1-7An offshore single pile structure foundation and a construction method thereof according to an embodiment of the present invention are specifically described.

[0017] like Figure 1 As shown, the offshore single pile structure foundation comprises: a main pile 1, a suction tube assembly 2, and a grouting cover 3; the main pile 1 is a round tube made of steel plate with a thick lower part and a thinner upper part, and an interface flange is provided on the top to meet the installation of other loads such as offshore wind turbines, and is driven into the seabed to a certain depth by a pile hammer to meet the vertical load bearing requirements; the suction tube assembly 2 is sleeved on the outside of the main pile 1, at a position where the pile diameter is relatively thick, and penetrates into the top plate and adheres to the mud surface through suction, and after the installation is completed, high-strength cement slurry grouting material is poured between the annuli to support the horizontal load of the main pile 1 at this position and improve its horizontal bearing capacity; the grouting cover 3 is installed on the top of the suction tube assembly 2, and is sealed after the high-strength cement slurry grouting material is poured between the annuli to protect the slurry inside the annular space from being washed away by the external seawater, thereby playing a protective effect; through this structural form, a smaller mud penetration depth can be achieved to achieve better bearing performance, and the long-term safety and stability of the loads placed on the upper part can be met.

[0018] like Figure 2 As shown, the main pile 1 is a round tube which is thicker at the bottom and thinner at the top and is rolled and welded into one piece by steel plates. From top to bottom, they are an upper pipe pile 13, a reducer 12, and a lower pipe pile 11, all of which are made by rolling steel plates. The wall thickness of the steel plate and the plate thickness and material selected are different according to the top load and the use area. The top flange 14 is coaxially welded to the top of the upper pipe pile 13. It is a flange ring according to the size of the upper fan connection flange or other upper connection load requirements. It is made of steel by integral forging, and can also be made by split welding to meet the load and strength requirements. According to the different upper loads, the length and diameter of the lower pipe pile 11 can be adjusted accordingly, so that the driving depth does not enter the high-strength soil layer, meeting the long-term bearing needs.

[0019] like Figures 3 to 6As shown, the suction cylinder assembly 2 is an annular structural member, which is formed by rolling and welding steel plates into a circular ring structure with an open bottom, a hollow middle and multiple compartments around it. It includes: an annular suction cylinder assembly 21, a reinforcing support 22, an intermediate support sleeve 23, an inner straightening boss 24, a vertical guide pulley 25, and a grouting isolation ring 26; according to the number of circumferential compartments, it is generally divided into 6 to 8 compartments, that is, it includes 6 to 8 groups of annular suction cylinder assemblies 21, and the annular suction cylinder assembly 21 is formed by a compartment plate 211 cut and processed by steel plates, a compartment top plate 218, an outer ring plate 212 cut and rolled into an arc, and an inner ring plate 2111 to form a circle. The arc-shaped bottom open structural member; the outer diameter of the outer ring plate 212 is generally more than 25m, which meets the larger bearing area and realizes the effective bearing of the horizontal load; the inner diameter of the inner ring plate 2111 is 4 to 6m larger than the outer diameter of the lower pipe pile 11, so as to avoid the scouring pit of the main pile 1 affecting the initial sealing of the suction cylinder assembly 2 entering the mud; a trapezoidal anti-pulling reinforcement bracket 213 is vertically welded at a certain angle on the outside of the outer ring plate 212, which is axially aligned with the compartment plate 211, and the barbed protrusion at the bottom of the bracket can limit the structure of the suction cylinder assembly 2 from being pulled out under the horizontal load, thereby improving the structural stability, and some holes can also be opened on it, further Improve the pull-out resistance; an inverted cone-shaped scour protection cover 214 made of rolled steel plate is welded concentrically on the top of the outer ring plate 212. When the cabin top plate 218 is close to the mud surface, the cone cover is embedded in the seabed mud surface to form a slope from the outside to the center of the suction cylinder assembly 2, which can well guide the scouring water flow upward to prevent the scouring of the periphery of the suction cylinder assembly 2; since the scour protection cover 214 is arranged in a circle and has many water holes, it is convenient to insert it below the seabed mud surface. Similarly, a structure similar to a grid can be used to meet the same functional performance; the scour protection cover 214 has a pull-out reinforcement elbow at the compartment plate 211 Plate 213, a triangular supporting bracket 215 is arranged on the axis corresponding to the interval anti-pullout reinforcement bracket 213 and the bulkhead reinforcement plate 216, which is manufactured by cutting and welding of steel plates to ensure the structural rigidity and strength of the inverted cone scour protection cover 214; axial and radial bulkhead reinforcement plates 216 and bulkhead plate reinforcement brackets 217 are welded inside the compartment structure and at the lower part of the cabin top plate 218 to form a mesh reinforcement, and the plate height is generally 400 to 600 mm, so that the annular suction cylinder assembly 21 can withstand better internal pressure during penetration, and more water holes are opened on the upper part close to the cabin top plate 218, which is beneficial to the discharge of water in the cylinder during penetration.In order to improve the pressure difference bearing capacity between adjacent cabins, the partition plate reinforcement brackets 217 on both sides of the partition plate 211 are widened or curved for reinforcement. The inner ring plate 2111 is welded and connected with an annular support bracket 2110 in the radial direction. The inner ring plate 2111 is a steel plate with a right-angle trapezoidal shape and a slight angle at the bottom. The plate surface is aligned with the partition plate 211. The inner vertical edge is welded and connected with the outer ring of the middle support sleeve 23 to form a centering guide for the inner hole, which is conducive to the suction cylinder assembly 2 being inserted into the upper pipe pile 13 and entering the middle support sleeve 23; the upper part of the two annular support brackets 2110 is welded with an annular cover plate 219 with holes to form a better support structure. According to actual needs, the annular cover plate 219 may not be installed; Multiple sets of annular suction cylinder assemblies 21 are combined to form an annular structure with an open bottom, divided into several cabins, and a bracket in the middle; a middle support sleeve 23 with a circular tubular top and a ring plate is coaxially welded at the center of the ring of the annular suction cylinder assembly 21. It is welded by rolling thick plates, and its inner diameter is 1m larger than the outer diameter of the lower pipe pile 11, with a good gap, which is convenient for installation; reinforced supports 22 with the same number as the cabins are arranged on the outer circumference of the middle support sleeve 23, which are cut and welded into a triangular box body by steel plate cutting, and the bottom is connected to the cabin top plate 218 and the cabin plate 211 by strong node welding, and the facade is welded to the outer circle of the middle support sleeve 23, and the top is tightly attached to the lower end of the upper ring plate of the middle support sleeve 23. A high-strength support is formed, which is beneficial to the horizontal load transmission; in order to facilitate the suction cylinder assembly 2 to be smoothly aligned and inserted into the main pile 1, multiple sets of internal straightening bosses 24 and vertical guide pulleys 25 are welded on the circumference of the inner hole of the middle support sleeve 23; the internal straightening boss 24 is a vertical plate with an angle at the lower end cut from a steel plate, which is raised by 300~350mm, which is beneficial to the alignment and centering of the suction cylinder assembly 2 when it is inserted into the main pile 1. The number of circumferential arrangements meets the construction needs and realizes the circumferential centering adjustment. If necessary, 2~3 circles can be arranged vertically in the middle support sleeve 23, so that the suction cylinder assembly 2 and the main pile 1 can be better coaxial during installation, which is beneficial to the force transmission after grouting; the vertical guide pulley 25 protrusion height 350mm~400mm, the upper part of the conical support is equipped with rollers, so that it can roll in contact with the outer wall of the main pile 1, which is conducive to the better coaxial insertion of the suction cylinder assembly 2 into the main pile 1 for installation. According to different structures and constructions, rollers of different numbers, wheel diameters and materials can be arranged; a circular grouting isolation ring 26 is bonded and fixed at the lower end of the middle support sleeve 23 and flush with the cabin top plate 218. The ring is made of rubber material with a tapered lower end and a flat upper end. The outer ring is tightly attached to the hole of the middle support sleeve 23. The conical lower part is conducive to inserting the main pile 1, and can be embedded under the mud surface, increasing the annular grouting height of the middle support sleeve 23 and the lower section of the pipe pile 11, and achieving better horizontal load transfer. According to the needs of the sinking construction, there are also bases and related pipelines on the upper part of the annular suction cylinder assembly 21 to meet the installation of the sinking equipment. If grouting in the cylinder is required, there are also grouting pipelines corresponding to each cabin, which are installed according to actual construction needs.

[0020] like Figure 7As shown, the grouting cover 3 is an arc-shaped ring plate steel sheet structure, which is installed on the top of the annulus of the middle support sleeve 23 of the main pile and the 2-suction cylinder assembly, and fits with the reinforcing ring plate at the top of the middle support sleeve 23 and the inner straightening boss 24. After the cover is closed, the annulus grouting material is prevented from flowing out and external seawater scouring is avoided; the ring plate 31 is an arc segment cut and processed by steel plate, and generally 3 to 4 arc segment ring plates 31 form a whole, the inner diameter is consistent with the lower section pipe pile 11, and the outer diameter is smaller than the outer diameter of the reinforcing ring plate at the top of the middle support sleeve 23. In this way, if the suction cylinder assembly 2 is eccentric when inserted into the main pile 1, the annulus can also be covered; the upper end of the ring plate 31 is welded with 4 hanging points 32 cut by steel plates , to meet the needs of lifting, according to actual use, other forms of lifting points such as lifting rings and screws can also be used, arranged in different positions and distributed in different numbers; 2 to 3 circles of reinforcing vertical ribs 33 are welded and arranged on the inner side of the ring at the lower end of the ring plate 31 to ensure that it can be installed in the annulus even if it is eccentric; a round steel short section is welded at the lower end of the ring plate 31 with a length of 300 to 500 mm, which is inserted into the annular grouting material to form a fixation, and will not fall out after being washed by seawater; according to manufacturing characteristics, the bottom of the reinforcing vertical rib 33 can also have a curved hook or spiral structure to better improve the adhesion and fixation with the grouting material.

[0021] The implementation steps of the present invention are as follows: Step S1: transport the offshore monopile structure foundation to the offshore construction site, the transport ship is close to the crane ship, and the steel pile is hoisted and erected according to the monopile construction method. The pile is placed in the required installation position, lowered into the mud by its own weight, and then a pile hammer is used to drive the pile until it is driven into the designed depth. After the steel pile is completed, it is necessary to check whether there are any external structures such as the lifting points that affect the insertion of the suction cylinder assembly 2, and the suction cylinder is installed after cutting; Step S2: Install the sinking equipment on the upper equipment installation base of the annular suction cylinder assembly 21, ensure the connection between the sinking equipment and the suction cylinder assembly 2, and the lifting personnel go to the internal platform on the top of the main pile 1, then lift the suction cylinder assembly 2 with the sinking equipment as a whole to the top of the main pile 1, adjust the structure to align, and slowly lower it so that the annular support bracket 2110 guides the suction cylinder assembly 2 to gradually align with the main pile 1 and gradually lower it. At the same time, the personnel on the internal platform on the top of the main pile 1 direct the crane to adjust so that the end of the main pile 1 is gradually inserted into In the middle support sleeve 23, the hoisting swing amplitude is controlled so that the grouting isolation ring 26 passes through the top flange 14, and then slowly lowered to the vertical guide pulley 25 in the middle support sleeve 23 to stick to the outside of the upper pipe pile 13, and gradually lowered. At the same time, the position of the suction cylinder assembly 2 is controlled to be within the required range. The crane continues to hook down so that the lower part of the suction cylinder assembly 2 contacts the mud surface and slowly sinks, so that the structure can enter the mud by its own weight. Before entering the mud, if the sinking equipment needs to be tested in water, it can also be temporarily stopped during hoisting, and continue to be lowered after debugging is completed; Step S3: Start the penetration equipment to penetrate, check the airtightness of each compartment one by one, if there are scouring pits in some compartments that affect the sealing, use upper pressure weights or penetrate other compartments to drive them to deepen the mud depth to form a seal, if the closure cannot be achieved through penetration, necessary mud and sand can be backfilled into the inner area of ​​the inner ring plate 2111 to form a sealed area; after all compartments are sealed, suction cylinder penetration is carried out to maintain the overall horizontal penetration, and if it is uneven, the penetration of the compartment with faster penetration (low point) is suspended, and the slower (high point) compartment is penetrated, and the horizontality is adjusted to not more than 3‰, and it is gradually adjusted, and the penetration negative pressure allowed by the design at different depths is controlled until it penetrates to the bottom of the cabin top plate 218 and is close to the mud surface. At this time, the current of the water pump motor of the penetration equipment is close to zero, and the penetration is completed. The penetration equipment is hoisted and recovered, and then the valve on the pipeline is closed or a plugging device is installed to complete the suction cylinder assembly 2 penetration construction; Step S4: connect the grouting pipeline on the suction cylinder assembly 2, operate the grouting equipment on the water surface to penetrate the low-strength cement slurry of less than 5MPa into the gap in the suction cylinder assembly 2, discharge the water in the cabin, and ensure the long-term stability of the structure. If the penetration depth has reached the cabin top plate 218 close to the mud surface, there is no need to grout the cylinder; after the grouting in the cylinder is completed, close the relevant valves to seal it and recycle the grouting pipeline; Step S5: clean the grouting equipment of the deck, refill with high-strength cement slurry greater than 70MPa, insert the pipeline into the annulus between the middle support sleeve 23 and the lower pipe pile 11, put the pipe end close to the grouting isolation ring 26, and inject slurry to drain the seawater in the annulus; underwater divers check the grouting situation and stabilize the grouting pipeline to prevent it from falling out of the annulus; when the annulus grouting approaches the top of the middle support sleeve 23, the grouting cover 3 of the hoisting deck is used to cover the top of the annulus, leaving a piece of grouting cover 3, and after the grouting is flush with the end of the middle support sleeve 23, the last piece of grouting cover 3 is covered to form a complete ring, and the reinforcing vertical ribs 33 are inserted into the cement slurry for fixing, so that the overall structural stability is more reliable. After the grouting is completed, the equipment is recovered, the construction is completed, and the ship and machinery are withdrawn and demobilized.

[0022] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

Claims

1. An offshore monopile structure foundation, comprising a main pile (1) and a suction cylinder assembly (2), characterized in that: The main pile (1) is a round tube formed by rolling a steel plate, the suction cylinder assembly (2) is sleeved on the outside of the main pile (1), and a grouting cover (3) is installed on the top of the suction cylinder assembly (2); The main pile (1) is composed of an upper pipe pile (13), a diameter-changing section (12), and a lower pipe pile (11) from top to bottom, and a top flange (14) is coaxially welded to the top of the upper pipe pile (13); The suction cylinder assembly (2) is a steel plate rolled and welded into a circular ring-shaped structural member with an open bottom, a hollow middle and surrounding compartments. The suction cylinder assembly (2) is composed of an annular suction cylinder assembly (21), a reinforcing support (22), an intermediate support sleeve (23), an inner straightening boss (24), a vertical guide pulley (25), and a grouting isolation ring (26). According to the number of circumferential compartments, 6 to 8 groups of the annular suction cylinder assemblies (21) are selected to form the main body of the annular structure. The main body of the annular structure formed by the annular suction cylinder assembly (21) is coaxially welded with the intermediate support sleeve (23). The reinforcing supports (22) are arranged on the outer circumference of the intermediate support sleeve (23) in the same number as the cabins. The vertical surface of the reinforcing supports (22) is welded to the outer side of the intermediate support sleeve (23). The top of the reinforcing supports (22) is closely attached to the lower end of the upper ring plate of the intermediate support sleeve (23). The inner hole of the intermediate support sleeve (23) is welded with a plurality of sets of inner straightening bosses (24) and vertical guide pulleys (25). The lower end of the intermediate support sleeve (23) is bonded and fixed with the grouting isolation ring (26) at the same level with the cabin top plate of the annular suction cylinder assembly (21); The grouting cover (3) is an arc-shaped ring plate steel sheet structure, the main body of which is an arc-shaped ring plate (31) cut from a steel plate, the upper end of the ring plate (31) is welded with four groups of hanging points (32), and the lower end of the ring plate (31) is welded with 2 to 3 circles of reinforcing vertical ribs (33) on the inner side of the ring.

2. The offshore monopile structure foundation according to claim 1, characterized in that: The annular suction cylinder assembly (21) is a structural member with an arc-shaped bottom and an open bottom, which is formed by a compartment plate (211), a cabin top plate (218), an outer ring plate (212) cut and rolled into an arc shape, and an inner ring plate (2111); a trapezoidal anti-pulling reinforcement bracket (213) is vertically welded to the outside of the outer ring plate (212); a scour protection cover (214) made of steel plate and rolled into an inverted cone shape is concentrically welded to the top of the outer ring plate (212); the scour protection cover (214) is located between the compartment and the inner ring plate; The plate (211) is provided with an anti-pulling reinforcement elbow plate (213), and the interior of the compartment structure of the annular suction cylinder assembly (21) and the lower part of the cabin top plate (218) are welded with axial and radial bulkhead reinforcement plates (216) and compartment plate reinforcement elbow plates (217), and support elbow plates (215) are arranged on the corresponding axis between the anti-pulling reinforcement elbow plates (213) and the bulkhead reinforcement plates (216), and the inner ring plate (2111) is welded with an annular support elbow plate (2110) in the radial direction.

3. The offshore monopile structure foundation according to claim 1, characterized in that: The inner straightening boss (24) is a vertical plate with an angled lower end formed by cutting from a steel plate.

4. The offshore monopile structure foundation according to claim 1, characterized in that: The grouting isolation ring (26) is a ring made of rubber material, with a tapered lower end and a flat upper end. The outer ring of the grouting isolation ring (26) is tightly attached to the hole of the middle support sleeve (23).

5. The offshore monopile structure foundation according to claim 2, characterized in that: The anti-pulling reinforcement bracket (213) is axially aligned with the compartment plate (211), and the lower portion is in the form of a barb-shaped protrusion.

6. The offshore monopile structure foundation according to claim 2, characterized in that: An annular cover plate (219) with holes is welded on the upper part of the annular support bracket (2110).

7. A construction method for an offshore monopile structure foundation, using an offshore monopile structure foundation as claimed in claims 1 to 6, characterized in that: The construction method of the offshore monopile structure foundation comprises the following steps: Step S1: transport the offshore monopile structure foundation to the offshore construction site, the transport ship approaches the crane ship, and the steel pile is hoisted and erected according to the monopile construction method. The pile is then placed in the required installation position, lowered into the mud by its own weight, and then driven into the mud with a pile hammer until it reaches the designed depth. The steel pile is completed. It is necessary to check whether there are any structures such as the lifting point that may affect the insertion of the suction cylinder assembly (2). After cutting, the suction cylinder is installed; Step S2: hoist and install the equipment for sinking and penetration onto the upper equipment installation base of the annular suction cylinder assembly (21), ensure the connection between the sinking and penetration equipment and the suction cylinder assembly (2), and then hoist the suction cylinder assembly (2) with the sinking and penetration equipment to the top of the main pile (1) as a whole, adjust the structure to align, and slowly lower it so that the annular support bracket (2110) guides the suction cylinder assembly (2) to gradually align with the main pile (1), and gradually lower it. At the same time, the personnel on the internal platform on the top of the main pile (1) direct the crane to adjust so that the end of the main pile (1) is gradually inserted. Enter into the middle support sleeve (23), control the hoisting swing amplitude so that the grouting isolation ring (26) passes through the top flange (14), and then slowly lower it to the vertical guide pulley (25) in the middle support sleeve (23) to stick to the outside of the upper pipe pile (13), and gradually lower it, while controlling the position of the suction cylinder assembly (2) within the required range, and the crane ship continues to hook down so that the lower part of the suction cylinder assembly (2) contacts the mud surface and slowly sinks, so that the structure can enter the mud by its own weight. Before entering the mud, if the sinking equipment needs to be tested in water, it can also be temporarily stopped during hoisting, and continue to be lowered after the debugging is completed; Step S3: Start the penetration equipment to penetrate, check the sealing condition of each compartment one by one. If there is a scouring pit in some compartments that affects the sealing, a weight can be used on the top or other compartments can be used to drive it to penetrate deeper into the mud to form a seal. If the sealing cannot be achieved through penetration, necessary mud and sand can be backfilled into the inner area of ​​the inner ring plate (2111) to form a sealed area. After all compartments are sealed, suction cylinder penetration is carried out to maintain the overall horizontal penetration. If it is uneven, the penetration of the compartment with faster penetration (low point) is suspended, and the slower (high point) compartment is penetrated. The horizontality is adjusted to not more than 3‰, and it is gradually adjusted. Control is performed according to the penetration negative pressure allowed by the design at different depths until the penetration reaches the bottom of the compartment top plate (218) and is close to the mud surface. At this time, the current of the water pump motor of the penetration equipment is close to zero, and the penetration is completed. The penetration equipment is hoisted and recovered, and then the valve on the pipeline is closed or a plugging device is installed to complete the suction cylinder assembly (2) penetration construction. Step S4: Connect the grouting pipeline on the suction cylinder assembly (2), operate the grouting equipment on the water surface to inject low-strength cement slurry with a pressure of less than 5 MPa into the gap in the suction cylinder assembly (2), discharge the water in the cabin, and ensure the long-term stability of the structure. If the penetration depth has reached the cabin top plate (218) close to the mud surface, grouting in the cylinder is not required. After the grouting in the cylinder is completed, close the relevant valves to seal it and recycle the grouting pipeline; Step S5: Clean the deck grouting equipment, refill with high-strength cement slurry with a strength of more than 70 MPa, insert the pipeline into the annulus between the middle support sleeve (23) and the lower pipe pile (11), place the pipe end close to the grouting isolation ring (26), and inject slurry to drain the seawater in the annulus; underwater divers check the grouting situation and stabilize the grouting pipeline to prevent it from falling out of the annulus; when the annulus grouting approaches the top of the middle support sleeve (23), the deck grouting cover (3) is hoisted to seal the top of the annulus, leaving a piece of grouting cover (3), and after the grouting is flush with the end of the middle support sleeve (23), the last piece of grouting cover (3) is sealed to form a complete ring, and the reinforcing vertical reinforcement (33) is inserted into the cement slurry to fix it, so that the overall structural stability is more reliable. After the grouting is completed, the equipment is recovered, the construction is completed, and the ship and machinery are withdrawn and demobilized.

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