Large-diameter underwater production protection structure and construction method thereof

Abstract

The invention discloses a large-diameter underwater production protection structure and a construction method thereof.The large-diameter underwater production protection structure comprises a barrel, a base disc and a top cover, the barrel is divided into a lower pipe section, a middle pipe section and an upper pipe section according to construction capacity, and the lower pipe section, the middle pipe section and the upper pipe section are sequentially connected from bottom to top; the upper pipe section, the middle pipe section and the lower pipe section are all composed of arc plates. The cylinder body, the base disc and the top cover are respectively manufactured on the land and are respectively installed under the seabed mud surface. According to the large-diameter underwater production protection structure, the strict construction technological process is designed, it is ensured that the size precision of all links in the construction process meets the requirement, measures for controlling the size precision are provided, and in other words, a rolled arc plate is placed on a specially-made temporary placement tool to reduce deformation of the arc plate; defining a first ground sample datum line and a second ground sample datum line, and taking the datum lines as references for all assembly and installation; and a perpendicularity regulator and a levelness regulator are used for carrying out position fine adjustment on the paired arc plates.

Description

Technical Field

[0001] The invention belongs to the technical field of marine engineering, and in particular relates to a large-diameter underwater production protection structure and a construction method thereof. Background Art

[0002] In order to exploit the oil and gas resources in the navigable area, a development model of "underwater production system + supporting platform" below the mud surface can be adopted, that is, a large-diameter underwater production protection structure is placed below the mud surface, and the oil and gas production facilities are arranged inside it. The exploited oil and gas resources are transported to the supporting platform through subsea pipelines, so as not to affect normal navigation.

[0003] This type of underwater production protection structure can not only avoid conflicts in sea use and protect internal production facilities, but also avoid the risks of ships running aground and falling objects. Since the underwater production protection structure has a large diameter-to-thickness ratio and strict tolerance requirements, a strict construction process needs to be designed to ensure that the dimensional accuracy of each link in the construction process meets the requirements.

[0004] Therefore, it is urgent to design a construction process for a large-diameter underwater production protection structure to solve the above-mentioned construction problems of the underwater production protection structure. Summary of the invention

[0005] In order to solve the technical problem mentioned in the background technology that the underwater production protection structure has a large diameter-to-thickness ratio and strict tolerance requirements, and therefore requires the design of a strict construction process, a large-diameter underwater production protection structure is provided to solve the problem of deep-water lifting.

[0006] To achieve the above objectives, the specific technical solutions of the large-diameter underwater production protection structure of the present invention are as follows: A large-diameter underwater production protection structure includes a cylinder, a base plate and a top cover. The cylinder is divided into a lower pipe section, a middle pipe section and an upper pipe section according to the construction capacity. The lower pipe section, the middle pipe section and the upper pipe section are connected in sequence from bottom to top. The upper pipe section, the middle pipe section and the lower pipe section are all composed of arc plates. The cylinder, the base plate and the top cover are respectively manufactured on land and installed under the mud surface of the seabed.

[0007] Furthermore, the cylinder, base plate and top cover are respectively manufactured on land. After the manufacturing on land is completed, a floating crane is used to install the base plate into the cylinder through a specific guide structure, and a floating crane is used to install the top cover above the cylinder.

[0008] Furthermore, the lower pipe section, the middle pipe section and the upper pipe section are composed of a plurality of arc-shaped arc plates, and the arc plates are adjusted in verticality by a vertical adjuster, and in horizontality by a horizontal adjuster.

[0009] Further, the arc plate is pre-placed on a temporary placement fixture for dimensional measurement.

[0010] Furthermore, the lower pipe section includes a first lower pipe section and a second lower pipe section, and the arc plates of the first lower pipe section and the second lower pipe section are built on the first ground sample reference line through the assembly pier, and the first ground sample reference line is positioned with the center of the cylinder as the origin.

[0011] Furthermore, the middle pipe section includes a first middle pipe section and a second middle pipe section, and the arc plates of the first middle pipe section, the second middle pipe section and the upper pipe section are constructed on the second ground sample reference line through guide plates.

[0012] Furthermore, the first radial support, the second radial support and the third radial support are respectively added to the lower pipe section, the middle pipe section and the upper pipe section during the construction and hoisting process to increase the structural rigidity and reduce deformation.

[0013] Furthermore, the top cover is composed of a top cover main frame, a small hatch cover, a sealing rubber and a main hanging point. The top cover main frame and the small hatch cover are manufactured separately and installed underwater separately. The top cover main frame is installed above the cylinder, and a ring-shaped sealing rubber is arranged between the top cover and the cylinder to prevent mud and sand from entering the cylinder.

[0014] A construction method for a large-diameter underwater production protection structure mainly comprises the following steps: S1. The arc plate needs to be placed on a special temporary placement tool for dimensional measurement. After the dimensional tolerance requirements are met, the arc plate is ready for installation; S2, assembly piers are arranged every 12°, totaling 30, and guide plates are arranged every 30°, totaling 12. The lower pipe section is directly constructed on the assembly piers, and the middle pipe section and the upper pipe section are constructed on the guide plates; S3. Install the arc plates one by one according to the first ground sample reference line and the second ground sample reference line. Use channel steel to fix the arc plates on both sides to prevent wind. Use the verticality adjuster to adjust the verticality of the arc plates. Use CNC-cut horse-lined plates to fix the longitudinal seams between the arc plates. S4, sequentially installing the first lower pipe section and the first middle pipe section according to S3, using spot welding for the longitudinal seams between the arc plates, and using a levelness adjuster to adjust the levelness of the arc plates; S5. Install the second lower pipe section on the first lower pipe section, install the second middle pipe section on the first middle pipe section, use horse racks to fix them, and remove the channel steel support after inspection; S6. Install the first radial support and the second radial support inside the lower pipe section and the middle pipe section respectively. The contact positions between the lower pipe section and the first radial support, the middle pipe section and the second radial support should avoid the annular seam and the longitudinal seam; S7. Weld a temporary lifting point on the second radial support, use a crawler crane to lift the middle pipe section to the lower pipe section and assemble and weld them; S8. The upper pipe section is constructed in the same manner. During the construction process, the third radial support and the second T-shaped rib of the outer wall need to be installed inside. During welding, multiple welds are welded symmetrically at the same time. S9. Using the same method, use a crawler crane to lift the upper pipe section onto the middle pipe section and assemble and weld them; S10, assembling and installing the first T-shaped rib according to the position of the second T-shaped rib; S11, dismantle the first radial support except the first lower pipe section, lift the base plate using a sling designed according to the weight and center of gravity of the base plate, and place the base plate into the cylinder along the guide structure for trial installation; S12. Remove some assembly pads that affect the entry position of the SPMT self-propelled modular transport vehicle; S13. Arrange temporary supports at the contact position between the SPMT self-propelled module transporter and the large-diameter underwater production protection structure body, use the SPMT self-propelled module transporter to transport the large-diameter underwater production protection structure body to the front of the wharf and load it onto the ship, and after loading, remove the first radial support of the first lower pipe section and withdraw to land; S14, manufacturing the main frame of the top cover and the small hatch cover, and after the manufacturing is completed, installing the main frame of the top cover and the small hatch cover underwater respectively.

[0015] Furthermore, the lifting points are arranged on the second radial support and the third radial support to lift the middle pipe section and the upper pipe section.

[0016] The large-diameter underwater production protection structure of the present invention has the following advantages: By designing a strict construction process, we ensure that the dimensional accuracy of each link in the construction process meets the requirements, and provide measures to control dimensional accuracy, that is, placing the arc plate after rolling on a special temporary placement tool to reduce the deformation of the arc plate; delineating the first ground sample reference line and the second ground sample reference line, all assembly and installation are based on the reference line; using the verticality adjuster and the horizontality adjuster to fine-tune the position of the assembled arc plate; using the first radial support, the second radial support, and the third radial support inside the lower pipe section, the middle pipe section, and the upper pipe section respectively to increase the structural rigidity. The design of the guide structure enables the base plate and the top cover to accurately fall into the predetermined installation position during trial installation and underwater installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a temporary placement tool for producing arc plates of large-diameter underwater protective structures of the present invention; Figure 2 A schematic diagram of placing assembly piers and guide plates on the ground sample reference line of the large-diameter underwater production protection structure of the present invention; Figure 3 It is a schematic diagram of sections of a large-diameter underwater production protection structure of the present invention; Figure 4 It is a schematic diagram of the windproof fixation of the channel steel of the large-diameter underwater production protection structure of the present invention; Figure 5 It is an overall schematic diagram of the verticality regulator of a large-diameter underwater production protection structure of the present invention; Figure 6 It is an overall schematic diagram of the horizontality regulator of a large-diameter underwater production protection structure of the present invention; Figure 7 It is an overall schematic diagram of the radial support of the large-diameter underwater production protection structure of the present invention; Figure 8 It is a schematic diagram of the suspension point of the large-diameter underwater production protection structure of the present invention; Fig. 9 It is a schematic diagram of the installation of the T-shaped rib of the large-diameter underwater production protection structure of the present invention; Fig.10 It is a schematic diagram of temporary support for a large-diameter underwater production protection structure of the present invention; Fig.11 It is a schematic diagram of the overall structure of the large-diameter underwater production protection structure of the present invention.

[0018] Description of the markings in the figure: 1. Arc plate; 2. Temporary placement of tooling; 3. First ground sample reference line; 4. Second ground sample reference line; 5. Assembly cushion; 6. Guide plate; 7. Lower pipe section; 71. First lower pipe section; 72. Second lower pipe section; 8. Middle pipe section; 81. First middle pipe section; 82. Second middle pipe section; 9. Upper pipe section; 10. Channel steel; 11. Verticality adjuster; 12. Horse plate; 13. Horizontality adjuster; 14. First radial support; 15. Second radial support; 16. Third radial support; 17. Lifting point; 18. Second T-shaped rib; 19. First T-shaped rib; 20. SPMT self-propelled module transporter; 21. Large-diameter underwater production protection structure body; 22. Temporary support; 23. Top cover. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0021] Please refer to the attached Figure 1 To Attachment Fig.11 The large diameter underwater production protection structure of the present invention is described.

[0022] like Figure 1 As shown, the large-diameter underwater production protection structure in the present invention includes a cylinder, a base plate and a top cover. The cylinder is divided into: a lower pipe section 7, a middle pipe section 8 and an upper pipe section 9 according to the construction capacity. The lower pipe section 7, the middle pipe section 8 and the upper pipe section 9 are connected in sequence from bottom to top. The upper pipe section 9, the middle pipe section 8 and the lower pipe section 7 are all composed of an arc plate 1; the cylinder, the base plate and the top cover are respectively manufactured on land and installed under the mud surface of the seabed. By designing a strict construction process, the dimensional accuracy of each link in the construction process is ensured to meet the requirements, and measures for controlling dimensional accuracy are provided, that is, the arc plate 1 after rolling is placed on a special temporary placement tool 2 to reduce the deformation of the arc plate; the first ground sample reference line 3 and the second ground sample reference line 4 are delineated, and all assembly and installation are based on the reference line; the verticality adjuster 11 and the horizontality adjuster 13 are used to fine-tune the position of the assembled arc plate 1; the first radial support 14, the second radial support 15, and the third radial support 16 are used inside the lower pipe section 7, the middle pipe section 8, and the upper pipe section 9 respectively to increase the structural rigidity. The design of the guide structure enables the base plate and the top cover to accurately fall into the predetermined installation position during trial installation and underwater installation.

[0023] Further, if Figure 1 As shown, the cylinder, base plate and top cover are respectively manufactured on land. After the manufacturing on land is completed, a floating crane is used to install the base plate into the cylinder through a specific guide structure, and a floating crane is used to install the top cover 23 on top of the cylinder; the lower pipe section 7, the middle pipe section 8 and the upper pipe section 9 are composed of a plurality of arc-shaped arc plates 1, and the arc plates 1 are adjusted in verticality by a vertical adjuster 11, and in horizontality by a horizontal adjuster 13; the arc plates 1 are pre-placed on a temporary placement tool 2 for dimensional measurement.

[0024] In this embodiment, preferably, the large-diameter underwater production protection structure body 21 has an outer diameter of 24 meters and a height of 14.25 meters, and is divided from bottom to top into a lower pipe section 7, a middle pipe section 8 and an upper pipe section 9, wherein the lower pipe section 7 is divided from bottom to top into a first lower pipe section 71 and a second lower pipe section 72, the middle pipe section 8 is divided from bottom to top into a first middle pipe section 81 and a second middle pipe section 82, and the upper pipe section 9 is a single layer. Each layer is formed by splicing 7 arc plates 1.

[0025] Preferably, the lower pipe section 7, the middle pipe section 8 and the upper pipe section 9 are welded with the longitudinal seam first and then with the circumferential seam; the longitudinal seam is welded by skip welding and the circumferential seam is welded by starting from the middle and then back-welding toward both ends; during welding, multiple welds are welded symmetrically at the same time; when the weld is a double-sided groove, it is welded from both sides at the same time.

[0026] After the plate is cut and rolled in the workshop, it is transported to the prefabrication site for installation. The arc plate 1 needs to be placed on a special temporary placement tool 2 for size measurement. After the size tolerance requirements are met, the arc plate 1 is ready for installation to minimize the deformation of the arc plate 1.

[0027] The main body 21 of the large-diameter underwater production protection structure is divided into a lower pipe section 7, a middle pipe section 8, and an upper pipe section 9 from bottom to top. The lower pipe section 7 is built directly on the assembly cushion 5, and the middle pipe section 8 and the upper pipe section 9 are built on the guide plate 6.

[0028] Preferably, when installing the arc plate 1, use channel steel 10 for windproof fixation, use verticality adjuster 11 to adjust the verticality of the arc plate 1, use horizontality adjuster 13 to adjust the horizontality of the arc plate 1, and use horse plate 12 to fix the annular seam and longitudinal seam between the arc plates 1.

[0029] Further, if Figure 1 As shown, the lower pipe section 7 includes a first lower pipe section 71 and a second lower pipe section 72, and the arc plates 1 of the first lower pipe section 71 and the second lower pipe section 72 are built on the first ground sample reference line 3 through the assembly cushion 5, and the first ground sample reference line 3 is positioned with the center of the cylinder as the origin; the middle pipe section 8 includes a first middle pipe section 81 and a second middle pipe section 82, and the arc plates 1 of the first middle pipe section 81, the second middle pipe section 82 and the upper pipe section 9 are built on the second ground sample reference line 4 through the guide plate 6; the lower pipe section 7, During the construction and hoisting process, the middle pipe section 8 and the upper pipe section 9 are respectively added with the first radial support 14, the second radial support 15 and the third radial support 16 to increase the structural rigidity and reduce deformation; the top cover 23 is composed of a top cover main frame, a small hatch cover, a sealing rubber and a main lifting point, etc. The main frame of the top cover 23 and the small hatch cover are manufactured separately and installed underwater separately; the main frame of the top cover 23 is installed above the cylinder, and a ring-shaped sealing rubber is arranged between the top cover 23 and the cylinder to prevent mud and sand from entering the cylinder.

[0030] In this embodiment, preferably, the temporary placement tooling 2 is mainly used to reduce the deformation of the arc plate 1 during the temporary placement process after the arc plate 1 is rolled; the guide plate 6 is mainly used for guiding and positioning during the installation of the arc plate 1; when the SPMT self-propelled module transport vehicle 20 is rolled on and off the ship, a temporary support 22 structure is installed on the outside for transportation, without the need to use a floating crane or welding lifting points.

[0031] Preferably, the first ground sample reference line 3 and the second ground sample reference line 4 need to be marked on the ground in advance, all assembly and installation are based on the reference line, a 1.6-meter-high assembly cushion 5 is arranged at the first ground sample reference line 3, a guide plate 6 is arranged at the second ground sample reference line 4, and the arc plates 1 are installed one by one according to the first ground sample reference line 3 and the second ground sample reference line 4.

[0032] Preferably, before the SPMT self-propelled module transporter is rolled on and off the ship, the first radial supports 14 other than the first lower pipe section 71 are removed, part of the assembly cushion 5 that affects the entry position of the SPMT self-propelled module transporter 20 is removed, and temporary supports 22 are arranged at the contact position between the SPMT self-propelled module transporter 20 and the large-diameter underwater production protection structure body 21. The SPMT self-propelled module transporter 20 is used to transport the large-diameter underwater production protection structure body 21 to the front of the wharf and load it onto the ship. After loading is completed, the first radial supports 14 of the first lower pipe section 71 are removed and withdrawn to land.

[0033] The present application also provides a construction method for a large-diameter underwater production protection structure, which mainly includes the following steps: S1. The large-diameter underwater production protection structure body 21 is segmented. After the plates are cut and rolled in the workshop, they are transported to the prefabrication site for installation. The arc plate 1 needs to be placed on a special temporary placement tool 2 for size measurement. After the size tolerance requirements are met, the arc plate 1 is ready for installation; S2. According to the diameter of the large-diameter underwater production protection structure body 21, the first ground sample reference line 3 and the second ground sample reference line 4 are demarcated in advance on the ground. All assembly and installation are based on the reference line. A 1.6-meter-high assembly cushion 5 is arranged at the first ground sample reference line 3, and a guide plate 6 is arranged at the second ground sample reference line 4. The assembly cushion 5 is arranged every 12°, for a total of 30, and the guide plate 6 is arranged every 30°, for a total of 12. The lower pipe section 7 is directly constructed on the assembly cushion 5, and the middle pipe section 8 and the upper pipe section 9 are constructed on the guide plate 6; S3, according to the first ground sample reference line 3 and the second ground sample reference line 4, the arc plates 1 are installed one by one. In order to reduce the influence of wind force on the construction process, the two sides of the arc plates 1 are fixed with channel steels 10 for windproof, the verticality of the arc plates 1 is adjusted with a verticality adjuster 11, and the longitudinal seams between the arc plates 1 are fixed with CNC-cut horse-lined plates 12; S4, sequentially install the first lower pipe section 71 and the first middle pipe section 81 according to S3, use spot welding for the longitudinal seams between the arc plates 1, and use the levelness adjuster 13 to adjust the levelness of the arc plates 1; S5. After the first lower pipe section 71 and the first middle pipe section 81 have been inspected, the second lower pipe section 72 is installed on the first lower pipe section 71, and the second middle pipe section 82 is installed on the first middle pipe section 81, and the horse plate 12 is used to fix them. After the inspection, the channel steel 10 support is removed; S6. Weld the longitudinal seams and circumferential seams between the arc plates 1. During welding, multiple welds should be welded symmetrically at the same time, and certain welding processes and welding techniques should be used to ensure that deformation is controlled to a minimum. S7. Install the first radial support 14 and the second radial support 15 inside the lower pipe section 7 and the middle pipe section 8 respectively. The contact positions between the lower pipe section 7 and the first radial support 14, the middle pipe section 8 and the second radial support 15 should avoid the annular seam and the longitudinal seam; S8, welding a temporary hanging point 17 on the second radial support 15, using a crawler crane to hang the middle pipe section 8 onto the lower pipe section 7 and assemble and weld them; S9. The upper pipe section 9 is constructed in the same manner. During the construction process, the third radial support 16 and the second T-shaped rib 18 of the outer wall need to be installed inside. During welding, multiple welds are welded symmetrically at the same time, and certain welding processes and techniques are used to ensure that deformation is controlled to a minimum. S10, using the same method, using a crawler crane to lift the upper pipe section 9 onto the middle pipe section 8 and assemble and weld them; S11, assembling and installing the first T-shaped rib 19 according to the position of the second T-shaped rib 18, welding symmetrically and simultaneously with multiple welds, and using certain welding processes and techniques to ensure that deformation is controlled to a minimum; S12, dismantle the first radial supports 14 other than the first lower pipe section 71, lift the base plate using a sling designed according to the weight and center of gravity of the base plate, and place the base plate into the cylinder along the guide structure for trial installation; S13, removing part of the assembly pad 5 that affects the entry position of the SPMT self-propelled modular transport vehicle 20; S14, arrange temporary supports 22 at the contact position between the SPMT self-propelled module transporter 20 and the large-diameter underwater production protection structure body 21, use the SPMT self-propelled module transporter 20 to transport the large-diameter underwater production protection structure body 21 to the front of the wharf and load it on board, and after loading, remove the first radial supports 14 of the first lower pipe section 71 and withdraw to land; S15, manufacturing the main frame of the top cover 23 and the small hatch cover, and installing the main frame of the top cover 23 and the small hatch cover underwater after the manufacturing is completed.

[0034] Further, if Figure 1 As shown, the hanging points 17 are arranged on the second radial supports 15 and the third radial supports 16 to hang the middle pipe section 8 and the upper pipe section 9 .

[0035] In this embodiment, preferably, the first radial support 14 and the second radial support 15 are respectively installed inside the lower pipe section 7 and the middle pipe section 8, a temporary lifting point 17 is welded on the second radial support 15, the middle pipe section 8 is lifted to the lower pipe section 7 by a crawler crane and assembled and welded, the third radial support 16 and the temporary lifting point 17 are installed inside the upper pipe section 9, and the upper pipe section 9 is lifted to the middle pipe section 8 by a crawler crane and assembled and welded in the same way; when constructing the upper pipe section 9, the third radial support 16 and the second T-shaped rib 18 of the outer wall are installed inside, the upper pipe section 9 is lifted to the middle pipe section 8 by a crawler crane and assembled and welded, the first T-shaped rib 19 is assembled and installed according to the position of the second T-shaped rib 18, and the second T-shaped rib 18 is connected to the top cover 23 arranged on the upper pipe section 9, and a rubber strip is provided between the top cover 23 and the upper pipe section 9 to protect the internal equipment of the large-diameter underwater production protection structure body 21.

[0036] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A large diameter underwater production protection structure, It is characterized in that It includes a cylinder, a base plate and a top cover. The cylinder is divided into a lower pipe section, a middle pipe section and an upper pipe section according to the construction capacity. The lower pipe section, the middle pipe section and the upper pipe section are connected in sequence from bottom to top. The upper pipe section, the middle pipe section and the lower pipe section are all composed of arc plates. The cylinder, base plate and top cover are manufactured on land and installed under the mud surface of the seabed.

2. The large-diameter underwater production protection structure according to claim 1, It is characterized in that The cylinder, base plate and top cover are manufactured on land respectively. After the manufacturing on land is completed, a floating crane is used to install the base plate into the cylinder through a specific guide structure, and a floating crane is used to install the top cover on top of the cylinder.

3. The large-diameter underwater production protection structure according to claim 1, It is characterized in that The lower pipe section, the middle pipe section and the upper pipe section are composed of a plurality of arc-shaped arc plates, and the arc plates are used to adjust the verticality through a vertical regulator and the horizontality through a horizontal regulator.

4. The large-diameter underwater production protection structure according to claim 3, It is characterized in that The arc plate is pre-placed on a temporary placement fixture for dimensional measurement.

5. The large-diameter underwater production protection structure according to claim 3, It is characterized in that The lower pipe section includes a first lower pipe section and a second lower pipe section. The arc plates of the first lower pipe section and the second lower pipe section are built on the first ground sample reference line through the assembly pier. The first ground sample reference line is positioned with the center of the cylinder as the origin.

6. The large-diameter underwater production protection structure according to claim 3, It is characterized in that The middle pipe section includes a first middle pipe section and a second middle pipe section. The arc plates of the first middle pipe section, the second middle pipe section and the upper pipe section are constructed on the second ground sample reference line through guide plates.

7. The large-diameter underwater production protection structure according to claim 3, It is characterized in that During the construction and hoisting process, the first radial support, the second radial support and the third radial support are respectively added to the lower pipe section, the middle pipe section and the upper pipe section to increase the structural rigidity and reduce deformation.

8. The large-diameter underwater production protection structure according to claim 1, It is characterized in that The top cover is composed of a top cover main frame, a small hatch cover, sealing rubber and main lifting points. The top cover main frame and the small hatch cover are made separately and installed underwater separately. The top cover main frame is installed above the cylinder, and a ring-shaped sealing rubber is set between the top cover and the cylinder to prevent mud and sand from entering the cylinder.

9. A construction method for a large-diameter underwater production protection structure. It is characterized in that The main steps include: S1. The arc plate needs to be placed on a special temporary placement tool for dimensional measurement. After the dimensional tolerance requirements are met, the arc plate is ready for installation; S2, assembly piers are arranged every 12°, totaling 30, and guide plates are arranged every 30°, totaling 12. The lower pipe section is directly constructed on the assembly piers, and the middle pipe section and the upper pipe section are constructed on the guide plates; S3. Install the arc plates one by one according to the first ground sample reference line and the second ground sample reference line. Use channel steel to fix the arc plates on both sides to prevent wind. Use the verticality adjuster to adjust the verticality of the arc plates. Use CNC-cut horse-lined plates to fix the longitudinal seams between the arc plates. S4, sequentially installing the first lower pipe section and the first middle pipe section according to S3, using spot welding for the longitudinal seams between the arc plates, and using a levelness adjuster to adjust the levelness of the arc plates; S5. Install the second lower pipe section on the first lower pipe section, install the second middle pipe section on the first middle pipe section, use horse racks to fix them, and remove the channel steel support after inspection; S6. Install the first radial support and the second radial support inside the lower pipe section and the middle pipe section respectively. The contact positions between the lower pipe section and the first radial support, the middle pipe section and the second radial support should avoid the annular seam and the longitudinal seam; S7. Weld a temporary lifting point on the second radial support, use a crawler crane to lift the middle pipe section to the lower pipe section and assemble and weld them; S8. The upper pipe section is constructed in the same manner. During the construction process, the third radial support and the second T-shaped rib of the outer wall need to be installed inside. During welding, multiple welds are welded symmetrically at the same time. S9. Using the same method, use a crawler crane to lift the upper pipe section onto the middle pipe section and assemble and weld them; S10, assembling and installing the first T-shaped rib according to the position of the second T-shaped rib; S11, dismantle the first radial support except the first lower pipe section, lift the base plate using a sling designed according to the weight and center of gravity of the base plate, and place the base plate into the cylinder along the guide structure for trial installation; S12. Remove some assembly pads that affect the entry position of the SPMT self-propelled modular transport vehicle; S13. Arrange temporary supports at the contact position between the SPMT self-propelled module transporter and the large-diameter underwater production protection structure body, use the SPMT self-propelled module transporter to transport the large-diameter underwater production protection structure body to the front of the wharf and load it onto the ship, and after loading, remove the first radial support of the first lower pipe section and withdraw to land; S14, manufacturing the main frame of the top cover and the small hatch cover, and after the manufacturing is completed, installing the main frame of the top cover and the small hatch cover underwater respectively.

10. The large-diameter underwater production protection structure according to claim 8, It is characterized in that The hanging points are arranged on the second radial support and the third radial support to hang the middle pipe section and the upper pipe section.

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