Special-shaped flat anchor for permanent mooring of offshore floating facilities and installation method thereof

Abstract

The application discloses a special-shaped flat anchor for permanent mooring of offshore floating facilities and a mounting method thereof, which comprises a bearing anchor plate, an anchor top plate, a scour prevention group plate and a mooring lug plate. The top edge of the bearing anchor plate is vertically connected with one side edge of the anchor top plate. The bearing anchor plate is inserted into the seabed to provide front extrusion contact with the soil, thereby providing main mooring bearing capacity. The other side edge of the anchor top plate is provided with a downwardly extending scour prevention group plate. The scour prevention group plate slows down the scouring of the surface soil of the seabed below the anchor top plate and simultaneously strengthens the structure of the anchor top plate as a reinforcing rib. The mooring lug plate is fixed on the bearing anchor plate along the longitudinal direction of the bearing anchor plate, and the lower part of the mooring lug plate is provided with an ear hole for connecting a mooring cable. The application can effectively solve the problems of design difficulty, great safety risk and high cost of permanent mooring of large offshore floating facilities in shallow sea with a water depth of 50 meters or less.

Description

Technical Field

[0001] This invention relates to the technical field of mooring anchors for offshore floating facilities, and in particular to a special-shaped flat anchor for permanent mooring of offshore floating facilities and its installation method. Background Technology

[0002] Traditional anchor types used for mooring offshore floating facilities mainly include mast anchors, mastless anchors, high holding capacity anchors, and special anchors. These long-established anchor types are mostly used for temporary mooring. For permanent mooring of large floating facilities, costly turret mooring is often used in oil engineering; while in the emerging offshore wind power industry and deep-sea aquaculture industry, pile anchors and suction anchors are mainly used.

[0003] With the development of the offshore wind power and deep-sea aquaculture industries, the demand for permanent mooring of large-scale offshore floating facilities is gradually increasing. However, the water depth in China's coastal waters is generally less than 50 meters. China's coastal waters are characterized by shallow water, thick silt layers, shallow bedrock, and weak soil bearing capacity. Shallow water means that the extreme mooring forces of floating facilities will be very large, leading to the risk of traditional mooring anchors dragging. Using pile anchors or suction anchors requires a significant increase in design dimensions, resulting in a rapid increase in costs. Shallow bedrock means that the design height of pile anchors and suction anchors is limited, potentially making it difficult to meet the bearing capacity requirements. Thick silt layers and weak soil bearing capacity mean that pile anchors and suction anchors, under height restrictions, need to have very large diameters, leading to poor economic efficiency. All these environmental conditions contribute to the increased cost of permanent mooring anchors, especially for the emerging floating wind turbines in China, where mooring costs account for a large proportion, posing a challenge to the overall economic viability of the projects.

[0004] Therefore, there is an urgent need to develop new types of anchors that can be used for permanent mooring to adapt to China's special marine environment conditions, while taking into account economy, construction feasibility and engineering reliability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a special-shaped flat anchor for permanent mooring of offshore floating facilities, which can effectively solve the problems of difficult mooring anchor design, high safety risks and high costs in the permanent mooring of large offshore floating facilities in shallow waters with a depth of less than 50 meters.

[0006] Another object of the present invention is to provide a method for installing a non-standard flat anchor for permanent mooring of offshore floating facilities.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A non-standard flat anchor for permanent mooring of offshore floating facilities includes a load-bearing anchor plate, an anchor top plate, scour protection group plates, and mooring lugs. The top edge of the load-bearing anchor plate is perpendicularly connected to one side edge of the anchor top plate. The load-bearing anchor plate is inserted into the seabed and makes direct contact with the soil to provide the main mooring load-bearing capacity. A downwardly extending scour protection group plate is provided at the other side edge of the anchor top plate. The scour protection group plate slows down the scouring of the surface soil of the seabed below the anchor top plate and also serves as a reinforcing rib to strengthen the structure of the anchor top plate. The mooring lugs are fixed to the load-bearing anchor plate longitudinally along the load-bearing anchor plate, and their lower parts are provided with lugs for connecting mooring cables.

[0009] Furthermore, the anchor top plate has a semi-circular structure, with a straight edge on one side and an arc-shaped edge on the other side. The straight edge is perpendicularly connected to the top edge of the supporting anchor plate, and the arc-shaped edge is perpendicularly connected to the top edge of the anti-scour group plate.

[0010] Furthermore, the anchor top plate is machined with multiple through holes to allow for air and water permeability during the installation of irregular flat anchors.

[0011] Furthermore, the supporting anchor plate has a rectangular structure, and its dimensions are set according to the mooring force requirements of the offshore floating facility.

[0012] Furthermore, the load-bearing anchor plate, anchor top plate, anti-scour group plate and mooring lug plate are all made of steel or cast steel.

[0013] Furthermore, the anchor top plate is provided with multiple installation slots around its perimeter, which are used to cooperate with the fixing wedges inside the suction cylinder during installation, thereby fixing the irregular flat anchor inside the suction cylinder.

[0014] Another objective of this invention is achieved through the following technical solution:

[0015] A method for installing a non-standard flat anchor for permanent mooring of offshore floating facilities, comprising the following steps:

[0016] S1. The irregular flat anchor is placed inside the suction cylinder as a whole, and the fixed wedge block is used to cooperate with the installation groove of the anchor top plate to constrain the horizontal displacement and rotation of the irregular flat anchor.

[0017] S2. Connect the lower end of the mooring cable to the ear hole of the mooring ear plate through a shackle, and temporarily store its upper end inside the top cover structure of the suction cylinder and fix it temporarily.

[0018] S3. A crane vessel is used to hoist and lower the suction cylinder to the seabed mud surface using a hoisting rope at the top of the suction cylinder.

[0019] S4. The suction cylinder is driven into place by using a negative pressure method, so that the suction cylinder is driven into the seabed mud to a predetermined depth, thereby allowing the irregular flat anchor to be driven into place as a whole.

[0020] S5. The suction cylinder is pulled out using the water injection method, and the suction cylinder is lifted from below the mud surface using a hoisting rope. At this time, the irregular flat anchor is fixed in the seabed soil due to the frictional resistance between the anchor plate and the soil.

[0021] S6. After the suction cylinder is lifted out of the sea by a crane vessel, the upper end of the mooring cable fixed inside the top cover structure of the suction cylinder is released, and the upper end of the mooring cable is connected to the mooring cable of the floating facility at sea to complete the installation of the irregular flat anchor.

[0022] Furthermore, the portion of the mooring cable that extends into the soil is a mooring chain, while the remaining portion is one or more combinations of anchor chains, fiber cables, mooring cables, and wire ropes.

[0023] Furthermore, the fixing wedge is welded and fixed inside the suction cylinder.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. The irregular flat plate anchor of the present invention has a sufficiently large vertical area, which directly provides sufficient bearing capacity through positive earth pressure, and does not rely on the reverse adsorption force and horizontal friction force of the soil to provide bearing capacity. Therefore, the decrease of the reverse adsorption force of the soil and the change of the horizontal friction force of the soil under the long-term cyclic mooring force can be ignored, so that the overall mooring bearing capacity will remain stable and the engineering reliability is high.

[0026] 2. The irregular flat plate anchor structure of the present invention is simple, and its bearing capacity is comparable to that of traditional permanent mooring pile anchors and suction anchors. The construction cost is significantly lower, and the economic feasibility is good.

[0027] 3. This invention uses a traditional suction cylinder that can be easily modified for installation. The installation method is simple, the installation efficiency is high, and the installation tools can be reused. It can be applied to large-scale installations, which greatly reduces the installation and construction costs. It effectively solves the problem that flat plate structures cannot be installed on the seabed by piling, making it possible to use flat plate anchor structures as permanent mooring anchors. Attached Figure Description

[0028] Figure 1 This is a front view of the irregular flat anchor of the present invention.

[0029] Figure 2 This is a side view of the irregular flat anchor of the present invention.

[0030] Figure 3 This is a top view of the irregular flat plate anchor of the present invention.

[0031] Figure 4 This is a schematic diagram of step S3 in the installation method of the present invention.

[0032] Figure 5 This is a schematic diagram of step S6 in the installation method of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Example 1:

[0035] like Figures 1 to 3 As shown, this embodiment provides a non-standard flat anchor for permanent mooring of offshore floating facilities, including a bearing anchor plate 1, an anchor top plate 2, scour protection group plates 3, and mooring lugs 4. The top edge of the bearing anchor plate 1 is perpendicularly connected to one side edge of the anchor top plate 2. The bearing anchor plate 1 is inserted into the seabed and makes contact with the soil surface to provide the main mooring bearing capacity. The other side edge of the anchor top plate 2 is provided with downwardly extending scour protection group plates 3. The scour protection group plates 3 reduce the scour of the surface soil of the seabed below the anchor top plate 2, and at the same time, they serve as reinforcing ribs to strengthen the structure of the anchor top plate 2. The mooring lugs 4 are fixed to the bearing anchor plate 1 along the longitudinal direction of the bearing anchor plate 1, and the lower part of the lugs is provided with lugs for connecting the mooring cable 5.

[0036] Specifically, the shape of the anchor plate 2 can be designed according to actual needs. In this embodiment, the anchor plate 2 has a semi-circular structure with a straight edge on one side and an arc edge on the other side. The straight edge is vertically welded to the top edge of the bearing anchor plate 1, and the arc edge is vertically welded to the top edge of the anti-scour group plate 3.

[0037] Multiple through holes 201 are machined on the anchor top plate 2 to allow for air and water permeability during the installation of irregular flat anchors.

[0038] Multiple installation slots 202 are provided around the four edges of the anchor plate 2, which are used to cooperate with the fixing wedges 9 inside the suction cylinder 7 during the installation process, so that the irregular flat anchor is fixed inside the suction cylinder 7.

[0039] Specifically, the bearing anchor plate has a rectangular structure, and its dimensions are set according to the mooring force requirements of the offshore floating facility. This ensures that the irregularly shaped flat anchor will not undergo significant deflection or displacement during the service life of the offshore floating facility, maintaining a stable mooring posture. Because the bearing anchor plate has a large vertical area, it provides sufficient bearing capacity directly through positive earth pressure, without relying on the reverse adsorption force of the soil or horizontal friction. Therefore, compared to traditional anchor types, it will have a more stable and considerable mooring bearing capacity. In this embodiment, the width of the bearing anchor plate is slightly smaller than the inner diameter of the suction cylinder, facilitating a clearance fit with the suction cylinder during construction.

[0040] Specifically, the load-bearing anchor plate, anchor top plate, anti-scour group plate and mooring lug plate are all made of steel or cast steel, and in this embodiment, they are made of steel.

[0041] Example 2:

[0042] like Figure 4 , Figure 5 As shown, this embodiment provides a method for installing a non-standard flat anchor for permanent mooring of offshore floating facilities, including the following steps:

[0043] S1. The irregular flat anchor is placed inside the suction cylinder 7. The suction cylinder 7 is a conventional suction cylinder, which is a cylindrical steel cylinder structure with an open bottom and a sealed top. The through hole of the anchor top plate 2 is located below the watertight hatch of the top cover structure inside the suction cylinder 7, which facilitates negative pressure penetration operation. Multiple fixing wedges 9 are welded around the top cover structure inside the suction cylinder 7 to cooperate with the installation slots of the anchor top plate 2. By cooperating with the installation slots 202 of the anchor top plate 2, the horizontal displacement and rotation of the irregular flat anchor are constrained.

[0044] S2. Connect the lower end of the mooring cable 5 to the ear hole of the mooring ear plate 4 through a shackle, and temporarily store its upper end inside the top cover structure of the suction cylinder 7 and fix it temporarily.

[0045] S3. A crane vessel is used to hoist and lower the suction cylinder 7 to the seabed mud surface using the hoisting rope 8 at the top of the suction cylinder 7.

[0046] S4. The suction cylinder 7 is inserted into the seabed using the traditional negative pressure method, so that the suction cylinder 7 is inserted to a preset depth below the seabed mud surface, thereby allowing the irregular flat anchor to be inserted into place as a whole.

[0047] S5. The suction cylinder 7 is pulled out using the traditional water injection method, and the suction cylinder 7 is lifted from the mud surface using the hoisting rope 8. At this time, the irregular flat anchor is fixed in the seabed soil due to the frictional resistance between the bearing anchor plate 1 and the soil. During the lifting of the suction cylinder 7, the lower end of the mooring cable 5 is fixed by the mooring lug 4, and the middle and upper sections of the mooring cable 5 rise with the suction cylinder 7 and are gradually pulled out.

[0048] S6. After the suction cylinder 7 is lifted out of the sea by the crane vessel, the upper end of the mooring cable 5 fixed inside the top cover structure of the suction cylinder 7 is released, and the upper end of the mooring cable 5 is connected to the mooring cable 6 of the floating facility 10 to the required complete length. After the mooring cable connection and installation are completed, the crane vessel leaves the construction site with the suction cylinder 7 to complete the installation of the irregular flat anchor.

[0049] In this embodiment, the length of the mooring cable 5 connected to the irregular flat anchor is designed to be from the designed depth of the mud surface to the designed lifting height above the sea surface. The length of the mooring cable 6 connected to the offshore floating facility is designed to be the required complete design mooring length minus the length of the mooring cable connected to the irregular flat anchor. Furthermore, to ensure that the mooring cable has sufficient wear resistance when it extends into the soil, the part of the mooring cable extending into the soil is designed as a mooring chain, and the remaining part can be one or more combinations of anchor chains, fiber cables, mooring cables, and wire ropes.

[0050] The irregularly shaped flat anchor of this invention, through the design of its load-bearing anchor plate, provides a large vertical area in positive contact with the soil, thus offering greater mooring load-bearing capacity and meeting the load-bearing requirements of permanent mooring. Simultaneously, it has a large lateral area at the top of the anchor in contact with the soil to prevent significant overturning of the anchor body and maintain its stability in the soil. Furthermore, through the innovative installation method of this invention, the irregularly shaped flat anchor can be installed to a designed depth below the seabed mud surface, and this installation method is quick and requires fewer construction resources.

[0051] In summary, the irregular flat anchor and its installation method of the present invention are economically feasible, constructionally feasible, and engineering reliable, and are worthy of promotion.

[0052] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A special-shaped flat anchor for permanent mooring of offshore floating facilities, characterized in that: The anchor includes a bearing anchor plate, an anchor top plate, scour protection plates, and mooring lugs. The anchor top plate has a semi-circular structure with a straight edge on one side and an arc-shaped edge on the other. The straight edge is perpendicularly connected to the top edge of the bearing anchor plate. The bearing anchor plate is inserted into the seabed and makes direct contact with the soil to provide the main mooring bearing capacity. The arc-shaped edge is perpendicularly connected to the top edge of the scour protection plates. The scour protection plates slow down the scouring of the surface soil of the seabed below the anchor top plate and also serve as reinforcing ribs to strengthen the structure of the anchor top plate. The anchor top plate has multiple through holes for ventilation and water permeability during the installation of the irregular flat anchor. Multiple installation slots are provided around the perimeter of the anchor top plate for engaging with the fixing wedges inside the suction cylinder during installation to fix the irregular flat anchor inside the suction cylinder. The mooring lugs are fixed to the bearing anchor plate longitudinally along the bearing anchor plate, and their lower parts have lugs for connecting mooring cables.

2. The irregular flat anchor for permanent mooring of offshore floating facilities according to claim 1, characterized in that: The supporting anchor plate has a rectangular structure, and its dimensions are set according to the mooring force requirements of the offshore floating facility.

3. The irregular flat anchor for permanent mooring of offshore floating facilities according to claim 1, characterized in that: The load-bearing anchor plate, anchor top plate, anti-scour group plate and mooring lug plate are all made of steel or cast steel.

4. A method for installing a non-standard flat anchor for permanent mooring of offshore floating facilities as described in any one of claims 1 to 3, characterized in that: Including steps, S1. The irregular flat anchor is placed inside the suction cylinder as a whole, and the fixed wedge block is used to cooperate with the installation groove of the anchor top plate to constrain the horizontal displacement and rotation of the irregular flat anchor. S2. Connect the lower end of the mooring cable to the ear hole of the mooring ear plate through a shackle, and temporarily store its upper end inside the top cover structure of the suction cylinder and fix it temporarily. S3. A crane vessel is used to hoist and lower the suction cylinder to the seabed mud surface using a hoisting rope at the top of the suction cylinder. S4. The suction cylinder is driven into place by using a negative pressure method, so that the suction cylinder is driven into the seabed mud to a predetermined depth, thereby allowing the irregular flat anchor to be driven into place as a whole. S5. The suction cylinder is pulled out using the water injection method, and the suction cylinder is lifted from below the mud surface using a hoisting rope. At this time, the irregular flat anchor is fixed in the seabed soil due to the frictional resistance between the anchor plate and the soil. S6. After the suction cylinder is lifted out of the sea by a crane vessel, the upper end of the mooring cable fixed inside the top cover structure of the suction cylinder is released, and the upper end of the mooring cable is connected to the mooring cable of the floating facility at sea to complete the installation of the irregular flat anchor.

5. The method for installing a non-standard flat anchor for permanent mooring of offshore floating facilities according to claim 4, characterized in that: The portion of the mooring cable that extends into the soil is a mooring chain, while the remaining portion is one or more of the following: anchor chain, fiber cable, mooring cable, and wire rope.

6. The method for installing a non-standard flat anchor for permanent mooring of offshore floating facilities according to claim 4, characterized in that: The fixing wedge is welded and fixed inside the suction cylinder.

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