A method for manufacturing and assembling a self-elevating offshore platform pile shoe

Abstract

This invention discloses a manufacturing and assembly method for a self-elevating offshore platform pile shoe, belonging to the field of marine engineering equipment manufacturing technology. The method includes: S1 bottom plate welding and anti-deformation pre-control; S2 mid-assembly welding of the pile core and inner cofferdam and second-precision closed-loop control; S3 segmented main body welding and process monitoring; S4 precision verification and trimming before blind tooth plate insertion; S5 blind tooth plate insertion and post-weld inspection; S6 segmented removal and post-weld free-state precision control. The assembly stage includes: S7 segmented assembly and ground line positioning; S8 welding of the closure joint and overall precision monitoring; S9 secondary fine-tuning after cofferdam and pile fixing frame construction. This invention achieves high-precision blind tooth installation through anti-deformation pre-control, multi-stage precision closed-loop control, and free-state measurement after removal; any deviations in horizontality and verticality after segmented removal are rectified before removal, eliminating the need for secondary correction after removal.

Description

Technical Field

[0001] This invention relates to the field of marine engineering equipment manufacturing technology, specifically to a method for manufacturing and assembling a self-elevating marine platform pile shoe. Background Technology

[0002] Spudcans are critical load-bearing structures for jack-up offshore platforms, used to insert the platform's legs into the seabed to support the entire platform's weight. Large spudcans typically consist of multiple sections (such as SC0*A, SC0*B, SC0*C, and SC0*E), which are assembled in situ within the dock. The SC0*E section features blind teeth, which are the teeth that mate with spudcan section A. The installation accuracy of these blind teeth directly affects the mating quality between the spudcan and the leg, as well as the meshing performance of the platform's jacking system. Therefore, the manufacturing of the SC0*E section with blind teeth is extremely critical.

[0003] Modern shipbuilding and marine engineering equipment manufacturing generally adopts a hierarchical manufacturing system of "small assembly - medium assembly - large assembly - final assembly" (see China Welding Association Group Standard T / CWAN 0040-2020). Among them: - Group assembly: The manufacturing process of assembling two or more parts into a component on a platform; - Intermediate assembly: The manufacturing process of combining small components with sheet metal or profiles to form flat or curved segments;

[0004] - Large assembly: The manufacturing process of combining intermediate assemblies and components to form three-dimensional segments.

[0005] The existing pile shoe manufacturing technology has the following technical defects: (1) The "cumulative effect" of welding deformation and the "anti-deformation pre-control" were not designed in a coordinated manner. Although the existing process knows that welding will cause deformation, it does not systematically pre-set the anti-deformation amount in the jig design stage. The shrinkage deformation after the overall welding was not considered when the base plate was placed on the jig, which led to the structure springback after the jig was removed and the blind tooth installation position deviation exceeded the standard.

[0006] (2) The timing of "removal" (loosening of the tire) lacks scientific basis. Current processes usually remove the tire for measurement only after all welding is completed. If the blind tooth installation position is found to be out of tolerance at this time, it is difficult to correct the already formed thick plate structure (40~80mm). Moreover, the structure is not made to reach "free equilibrium state" before removal of the tire, and the measurement data includes the influence of the tire constraint force, which cannot reflect the true residual deformation.

[0007] (3) Lack of "process intervention" mechanism for blind tooth installation. The existing process directly inserts the blind tooth piece after the main body welding is completed, without checking and trimming the center of the top plate blind tooth piece before insertion, which makes it difficult to insert the blind tooth piece or causes assembly stress due to forced assembly.

[0008] (4) Insufficient "stop point" settings for precision control. The existing process lacks a mechanism for mandatory inspection at key process nodes, and deviations in the welding process cannot be detected and corrected in a timely manner, resulting in deviations accumulating to the point of being irreversible in the final process.

[0009] (5) The "hydrogen removal treatment" after welding of special materials is neglected. The structure around blind teeth is often made of high-strength steel or special materials. If hydrogen is not removed in time after welding, cold cracks are likely to occur, affecting the structural safety. Summary of the Invention

[0010] The purpose of this invention is to provide a method for manufacturing and assembling a self-elevating offshore platform pile shoe. This method solves the technical problems of uncontrollable welding deformation accumulation and difficulty in ensuring the accuracy of blind tooth installation position in the prior art through systematic welding sequence design, anti-deformation pre-control, multi-stage precision closed loop, and free state measurement after demolding.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for manufacturing and assembling a self-elevating offshore platform pile shoe includes the following steps: The pile shoe consists of four sections: SC0*A, SC0*B, SC0*C, and SC0*E. Each section is manufactured in stages: "small assembly - medium assembly - large assembly". The SC0*E section has blind teeth that connect with the pile leg section A. The manufacturing and assembly welding of the SC0*E section includes the following steps: S1. Base Plate Welding and Anti-Deformation Pre-control: The base plate is welded into a whole in sections. The base plate is mounted on a jig. During the jig fabrication, a downward anti-deformation amount is pre-set at the triangular part of the base plate. The center position point of the pile shoe, the longitudinal and transverse baselines and the 120° radial angle line are marked, and permanent punch points are set. During the welding process, the deviation of the center line, the 120° azimuth line and the edge line are monitored in real time. After welding, the plumb line is used to check the fit between the spliced ​​plate and the ground line. If there is a deviation, it is corrected and adjusted to establish a horizontal reference closed loop. S2. Mid-assembly welding of pile core and inner circumference plate and second precision closed-loop control: hoist the pile core, use a plumb bob to position the pile core, and confirm alignment with the center of the pile shoe on the base plate; hoist the inner circumference plate, confirm the verticality of the inner circumference plate and the end difference with the base plate, the alignment of the longitudinal and transverse reference lines ≤ ±3mm, and the end difference reference edge ≤ ±2mm; add work area-level stop points, submit a pre-welding precision control inspection report after the inner circumference plate is assembled, and welding can only be carried out after all out-of-tolerance parts have been rectified and re-inspected and qualified; establish a radial reference closed loop, and complete the mid-assembly welding in the order from the inside to the outside; S3. Segmented main body welding and process monitoring: When welding the segmented main body, follow the WPS welding process. During the welding process, monitor and measure the deviation of the 120° baseline and longitudinal and transverse baselines of the pile shoe from the ground sample line every hour. If the deviation exceeds ±2mm, stop welding immediately and adjust the welding sequence before resuming construction. Monitor the deviation of the segmented baseline relative to the ground sample and the height baseline of the outer plate every two hours. S4. Precision verification and trimming before blind tooth plate insertion: After the main body of the segment is welded and before the blind tooth plate is inserted, use a total station to find the theoretical position of the center of the blind tooth plate on the top plate of the pile shoe, make a cross auxiliary tool and tap the cross punch point, use a plumb bob to verify the deviation between the center of the blind tooth plate on the top plate and the center of the blind tooth plate on the bottom plate, and trim the top plate and internal radial plate of the pile shoe according to the verified deviation to ensure that the blind tooth plate is successfully inserted into the theoretical position; S5. Blind tooth plate insertion and post-weld inspection: After the blind tooth plate is inserted, the projected length and the torsion angle of the blind tooth plate are inspected before and after welding to ensure that the blind tooth plate is installed in place to meet the tolerance; after the special material structure around the blind tooth plate is welded, hydrogen removal treatment is performed, and after hydrogen removal, it is covered with heat insulation cotton for slow cooling and then inspected according to the requirements. S6. Segmented removal of the mold and post-weld free state precision control: After the main body of the segment is welded and before the overall completion of the mold removal, the sealing points are removed to put the segment in a free state for 100% self-inspection; the precision control personnel issue a post-weld precision control report. Before the mold removal, all parts with out-of-tolerance horizontality and verticality must be rectified and re-inspected and qualified before the mold removal can be carried out. The overall assembly phase includes the following steps: S7. Segmented installation and ground sampling line positioning: Draw ground sampling lines in the dock, including longitudinal and transverse reference ground sampling lines, 120° angle lines, and outer contour lines of the closure opening; arrange steel piers and control the levelness of the pier surface; install SC0*E segments first, and use a three-dimensional positioning trolley and plumb bob for positioning to meet the requirement of ±2mm level of the upper opening of the three blind teeth, the alignment deviation between the 120° angle line of the ground sampling and the 120° angle reference line on the segment is ≤2mm, and the deviation of the line connecting the centers of the blind tooth pieces is ≤5mm; S8. Joint Welding and Overall Precision Monitoring: Segments SC0*A, SC0*B, and SC0*C are hoisted sequentially, and a 3D trolley is used for positioning to control the horizontal deviation of the outer side plate height baseline, the joint spacing, and the deviation from the longitudinal and transverse ground reference lines. After the four segments are positioned and assembled, the overall precision control is reported for inspection. After passing the inspection, the joint welding is performed according to WPS. During the welding process, the deviation of the 120° angle line is monitored at all times. If it exceeds ±2mm, welding is stopped immediately and the welding sequence is adjusted. S9. Secondary fine-tuning after the construction of the cofferdam and the fixed pile frame: After the construction of the cofferdam and the fixed pile frame is completed and the first pile leg is hoisted, the pile shoe is fine-tuned again using a three-dimensional trolley to ensure the precise connection between the blind teeth on the blind tooth plate and the pile leg section A.

[0012] Furthermore, the anti-deformation amount mentioned in step S1 is 10mm downwards, corresponding to an angle of 0.06°.

[0013] Furthermore, in step S2, the verticality of the pile core is ≤3mm, and the end difference of the non-reference edge is ≤±4mm.

[0014] Furthermore, the assembly welding sequence in step S2 is as follows: first, weld the connecting weld between the inner circumference plate and the bottom plate; then, weld the connecting weld between the ring rib plate and the inner circumference plate; and finally, weld the butt weld of the outer circumference plate.

[0015] Furthermore, the monitoring and measurement in step S3 includes: using a plumb bob to monitor the deviation of the segmented baseline relative to the ground sample, using a leveling instrument to monitor the height of the segmented outer plate reference sample, and creating a data table to record the dimensional monitoring of the pile shoe welding process.

[0016] Furthermore, the accuracy requirements for the blind tooth piece detection in step S5 are as follows: projection length L1=L2=L3=9500±8mm; |L1-L2|, |L2-L3|, |L3-L1|≤5mm; twist angle=60°≤0.5°.

[0017] Furthermore, in step S6, the 100% self-inspection content includes: overall level, main dimensions, end difference, baseline deviation, verticality, pile shoe center and cylinder position deviation.

[0018] Furthermore, in step S7, the surface level of the pier is controlled to be ±2mm, and the BL3000mm horizontal reference line is used to adjust the level for coarse positioning.

[0019] Furthermore, in steps S1, S2, S3, and S8, the welding is performed using CO2 gas shielded welding or submerged arc welding, with a preheating temperature of 80–150°C and an interpass temperature of 120–200°C.

[0020] Furthermore, after the pile shoe is manufactured, the overall 120° angle line deviation of the pile shoe is ≤2mm, the deviation of the center line of the blind tooth piece is ≤5mm, the twist angle of the blind tooth piece is ≤0.5°, and the success rate of the blind tooth piece insertion on the first attempt is ≥95%.

[0021] The beneficial effects of this invention are as follows: First, the method described in this application ensures that all areas with excessive horizontal and vertical deviations after segmented demolding are rectified before demolding, eliminating the need for secondary correction after demolding. Second, the one-time insertion rate of blind tooth pieces is significantly improved, avoiding assembly stress caused by forced assembly. Third, the overall 120° angle line deviation of the pile shoe is controlled within ±2mm, and the deviation of the line connecting the centers of the blind tooth pieces is ≤5mm. Fourth, hydrogen removal treatment eliminates the risk of cold cracking in the welding of special materials around the blind tooth piece, improving the safety of the structure; Fifth, the secondary fine-tuning after the construction of the well and the pile fixing frame ensures the precise connection between the pile legs and the blind tooth plate, and the meshing performance of the platform lifting system is significantly improved. Attached Figure Description

[0022] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort: Figure 1 This is a flowchart of the present invention; Figure 2 This is a top view of the pile shoe of the present invention; Figure 3 for Figure 2 The 3D view of the SC0*E segment shown; Figure 4 A schematic diagram for arranging monitoring baselines on the upper surface of the base plate; Figure 5 This is a schematic diagram of the base plate after welding. Figure 6 for Figure 5 The diagram shown is a schematic of the T-shaped row installed on the base plate. Figure 7 for Figure 6 A schematic diagram of the structure showing the welded bottom plate ring reinforcement and inner opening circumference plate on the bottom plate; Figure 8 A schematic diagram of line O"A connecting the center of the three blind tooth pieces to the center of the blind tooth piece. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper surface," "lower surface," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "forward," "reverse," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025]

Example 1

[0026] I. Pile Shoe Structure and Segmentation like Figure 2 , Figure 3 As shown, Project N1063 has four pile shoes, each consisting of four segments: - Segmentation SC0*A, segmentation SC0*B, segmentation SC0*C, segmentation SC0*E; The SC0*E segment comes with 3 blind teeth, which are arranged at 120° to each other and connect with the A segment of the pile leg.

[0027] Each segment is manufactured in a hierarchical manner: "small assembly - medium assembly - large assembly". - Small group assembly: Parts are assembled into components - Mid-level assembly: Small-scale assembly and panel assembly to form flat or curved segments (such as base plate and top plate components). - Large assembly: The middle assembly and component combination form three-dimensional segments (complete SC0*A segment, SC0*B segment, SC0*C segment, SC0*E segment). like Figure 1 As shown, the manufacturing and assembly welding of the SC0*E segment includes the following steps: Step S1: Base plate welding and anti-deformation pre-control (1) The base plate is assembled in multiple pieces on the jig, and extra shrinkage of the assembled plates is added during welding.

[0028] (2) For the base plate 1, construct the main frame for the pile shoe base plate. During frame construction, add a downward 10mm (0.06°) counter-deformation allowance at the triangular area of ​​the base plate. This counter-deformation must be taken into account during frame construction. The welded base plate, as shown... Figure 5 As shown.

[0029] (3) Securely connect the segmented tire plate and the tire frame to the pile shoe to ensure the stability of the segmented tire.

[0030] (4) When assembling and marking the bottom plate, mark the center of the pile shoe and the center of the blind tooth piece according to the dimensions shown in the drawing. The construction team marks the line according to the length of the oblique line, and the precision control team uses a total station to confirm the projected length and the length of the oblique line.

[0031] (5) After confirming that there are no errors, mark the center of the pile shoe and the center of the blind tooth piece on the pile shoe base plate and knock down the permanent punch point.

[0032] (6) During the welding process, monitoring baselines are arranged on the upper surface of the base plate: center line (passing through the geometric center of the pile shoe), 120° azimuth line (with the center as the origin, one line is arranged every 120°, corresponding to the 3 blind teeth), and border line (outer contour line of the base plate), as follows: Figure 4 As shown in the figure, the cross mark indicates the center of the blind tooth piece; the dashed circle indicates the center of the post.

[0033] (7) During the welding process, after each 1 / 3 of the weld length is completed, use a total station to check the straightness deviation of each monitoring line. If the deviation exceeds 2mm, stop welding, analyze the cause of the deviation and adjust the subsequent welding parameters.

[0034] (8) After the bottom plate 1 is welded, hang a plumb bob above the bottom plate, align the bottom of the plumb bob with the ground pattern line (the theoretical position line marked on the ground in advance), and check the conformity between the actual position after the plate is assembled and the ground pattern line.

[0035] (9) If a deviation is detected, it shall be corrected and adjusted by flame correction or mechanical pressing until the deviation of the center line, 120° azimuth line and border line from the ground sample line is ≤2mm, and a precise horizontal reference closed loop shall be established.

[0036] Step S2: Mid-assembly welding of pile core 3 and inner end plate and second-precision closed-loop control (1) First, hoist the pile core 3. Use a plumb bob to position the pile core 3, confirm that it is aligned with the center of the pile shoe of the base plate 1, and that the verticality of the pile core is ≤3mm.

[0037] (2) Lifting of small components, including the bottom plate ring reinforcement 7, T-shaped reinforcement 2, and inner opening circumference plate 6, such as Figure 6 , Figure 7 As shown.

[0038] (3) Use a plumb bob to confirm the verticality of the inner end plate 6 of the pile shoe and the end difference between the inner end plate 6 and the bottom plate 1 of the pile shoe.

[0039] (4) Positioning shall be carried out strictly in accordance with the longitudinal and transverse reference lines: the alignment of the longitudinal and transverse reference lines shall be ≤ ±3mm, the end difference of the reference edge shall be ≤ ±2mm, and the end difference of the non-reference edge shall be ≤ ±4mm. After confirming that there are no errors, spot welding shall be carried out.

[0040] (5) Add a work area-level stop point: After the inner opening panel is assembled, an inspection report must be submitted to the area precision control officer. The precision control officer issues the "Pre-welding precision control report for segmented inner opening panel (before adjustment)". After all the out-of-tolerance parts have been rectified (end differences must be handled before welding), the construction team submits a re-inspection report to the area precision control officer. Welding operations can only be carried out after the re-inspection is qualified.

[0041] (6) After establishing the radial reference closed loop, complete the assembly welding in the order from the inside to the outside: first weld the connecting weld between the inner circumference plate 6 and the bottom plate 1 (inner side weld), then weld the connecting weld between the ring rib plate and the inner circumference plate 6 (middle weld), and finally weld the butt weld of the outer circumference plate 5 (outer side weld) and the top panel 8.

[0042] (7) The welding sequence follows the principle of "symmetry, interval, and layering": the weld of each inner opening plate is welded in 2 to 3 layers with an interval of 15 minutes between layers, and the welding sequence of adjacent inner opening plates is carried out in an intermittent manner.

[0043] Step S3: Segmented main body welding and process monitoring (1) When welding the main body in sections, strictly follow the WPS (Welding Procedure Specification) and pay attention to the welding sequence.

[0044] (2) During the welding process, a plumb bob is used to monitor and measure the deviation of the 120° baseline and the longitudinal and transverse baselines from the ground sample line of the pile shoe every hour.

[0045] (3) If the deviation exceeds ±2mm, welding should be stopped immediately, and the supervisory team should be notified to discuss and adjust the welding sequence before proceeding with the construction.

[0046] (4) During the welding process, a plumb bob is used to monitor the deviation of the segment reference line relative to the ground sample, and a leveling instrument is used to monitor the height reference sample of the segment outer plate every two hours.

[0047] (5) Create a data table for monitoring the dimensions of the pile shoe welding process, record it and paste it on site.

[0048] (6) Mark the horizontal reference points on the bottom plate and outer side plate of the pile shoe, mark them and set permanent sample punch points to facilitate the construction team to use a level to check.

[0049] Step S4: Precision verification and trimming before blind tooth plate insertion (1) After the main body of the segment is welded and before the blind tooth piece 4 is inserted, the precision control team uses a total station to assist the construction team in finding the center of the blind tooth piece on the top plate of the pile shoe (the theoretical position of the blind tooth piece insertion) based on the projected length of 5485mm.

[0050] (2) The construction team made cross auxiliary tools on the top plate of the pile shoe and knocked out the cross punching point.

[0051] (3) Use a plumb bob to check the deviation between the center of the blind tooth plate of the top plate of the pile shoe and the center of the blind tooth plate of the bottom plate of the pile shoe (the welding shrinkage allowance will deviate from the actual welding shrinkage).

[0052] (4) Based on the verification deviation, the top plate of the pile shoe and the radial plate inside the pile shoe are trimmed to ensure that the blind tooth piece is successfully inserted into the theoretical position.

[0053] Step S5: Blind tooth plate insertion and post-weld inspection (1) After the blind tooth piece 4 is inserted, the precision control team uses a total station to check the projected lengths L1, L2, and L3 and the torsion angle of the blind tooth piece before and after welding. Figure 2 As shown.

[0054] (2) Accuracy requirements: L1=L2=L3=9500±8mm; |L1-L2|、|L2-L3|、|L3-L1|≤5mm; Twist angle=60°≤0.5°.

[0055] (3) Ensure that the blind tooth piece 4 on the blind tooth piece meets the tolerance and is installed in place. The construction team monitors the center of the blind tooth piece during the welding process.

[0056] (4) After the special material structure around the blind tooth piece is welded, hydrogen removal treatment must be performed. After hydrogen removal, cover with heat insulation cotton to slow cooling, and then carry out flaw detection inspection as required.

[0057] Step S6: Segmented removal of the substrate and fine control of the free state after welding (1) After the main body of the segment is welded and before the whole structure is completed and removed from the mold, the sealing point is removed so that the segment is in a free state.

[0058] (2) The construction team shall conduct 100% self-inspection and fill in the "Segmented Fabrication Completion Accuracy Inspection Form" truthfully and completely according to the requirements of the self-inspection form.

[0059] (3) After the construction team's self-inspection is completed, the inspector signs the report, which is then signed by the area foreman and submitted to the area precision control officer for post-weld precision control inspection. Inspection contents: overall level, main dimensions, end difference, baseline deviation, verticality, pile shoe center and cylinder position deviation.

[0060] (4) The precision control personnel shall issue a “Precision Control Report after Segmented Welding (Before Adjustment)”. Before the removal of the mold, all parts with excessive horizontal and vertical deviations must be rectified.

[0061] (5) The construction team shall submit the re-inspection to the regional precision control officer. Only after the re-inspection is qualified can the mold be removed.

[0062] (6) The regional precision control officer issues a “Segmented Completion Precision Control Report”.

[0063] (7) After the section is removed from the mold, the main dimensions of the parts that exceed the tolerance shall be rectified in accordance with the rectification requirements of the "Sectional Welding Post-Control Report (Before Adjustment)". After all the rectification is completed, the construction team shall submit the re-inspection to the regional control officer. After the re-inspection is qualified, the regional control officer shall issue the relevant "Sectional Completion Control Report".

[0064] III. Final Assembly and Launch Phase Step S7: Segmented mounting and ground sampling line positioning (1) Before the segmented hoisting, it is necessary to check whether the segmented baseline punch is missing, and use a paint pen to draw the longitudinal and transverse baselines, height baselines, center line of the top tooth of the blind tooth, and 120° on the E segment and other baseline markings.

[0065] (2) Verify the center data of the blind tooth piece in segment E, and transfer the 120° line of the center of the blind tooth piece in segment E to the outer side plate of segment E and attach the measuring patch. Also attach the patch to the height reference line of the other three segments in advance.

[0066] (3) Before the final assembly, simulate the assembly based on the data of the segmented closure joint, and correct the closure joint margin based on the simulation data.

[0067] (4) Before the sectional hoisting, the dock shall draw the ground pattern lines according to the precision control requirements, including the longitudinal and transverse reference ground pattern lines corresponding to the sectional, the 120° angle line, and the outer contour line of the E section of the pile shoe, and make paint markings.

[0068] (5) Arrange the steel supports in advance according to the support layout diagram, and control the levelness of the support surface to meet the ±2mm requirement by using a leveling instrument.

[0069] (6) The SC0*E segment is installed first, and the SC0*E segment is positioned by a three-dimensional positioning trolley according to the outer contour line of the closing opening.

[0070] (7) The positioning team uses a plumb bob to locate the front and back and the angle direction according to the segmented baseline and the ground sample baseline. The horizontal direction is located using a level.

[0071] (8) Positioning requirements for segment E: - Adjust the level according to the BL3000mm horizontal baseline for coarse positioning to meet the ±2mm requirement of the upper level of the three blind teeth; - The alignment deviation between the 120° angle line of the ground sample and the 120° angle baseline on the three outer side plates of the segment is ≤2mm; - After the entire structure is in place, verify that the deviation between the 120° ground sampling baseline OA at the center of the well and the line O"A connecting the center of the three blind tooth segments and the center of the blind tooth segments at the positive angle is ≤5mm. Figure 8 As shown.

[0072] (9) After the segmented hoisting and positioning is completed, profiles are needed to temporarily seal it to the pre-embedded iron at the bottom of the dock.

[0073] Step S8: Welding of the closing joint and overall precision monitoring (1) The SC0*A, SC0*B and SC0*C segments are hoisted in sequence, and the segments are positioned using a three-dimensional trolley.

[0074] (2) Strictly control the horizontal deviation of the height baseline of the outer side plate, the 100MK line spacing at the closure joint and the deviation from the longitudinal and transverse ground sample baseline.

[0075] (3) After the four sections of the pile shoe are positioned and assembled, the whole system is inspected and the data is reported. After the inspection is qualified, the joint is welded according to the WPS requirements.

[0076] (4) When welding the three segments SC0*A, SC0*B and SC0*C, it is necessary to monitor the 120° angle line of the pile shoe at all times. If a deviation occurs, the welding sequence needs to be adjusted in time.

[0077] (5) During the welding process, use a plumb bob to monitor and measure the deviation of the 120° baseline and the longitudinal and transverse baselines of the pile shoe from the ground sample line every hour. If the deviation exceeds ±2mm, welding should be stopped immediately, and the supervisory team should be notified to discuss and adjust the welding sequence before construction resumes.

[0078] (6) During the welding process, a plumb bob is used to monitor the deviation of the segment baseline relative to the ground sample, and a leveling instrument is used to monitor the height of the segment outer plate baseline sample every two hours. A data table of monitoring the dimensions of the pile shoe welding process is also made and pasted on site.

[0079] Step S9: Secondary fine-tuning after the construction of the cofferdam and pile foundation (1) After the construction of the cofferdam and the pile fixing frame is completed, the pile shoe is finely adjusted by a three-dimensional trolley when the first pile leg is hoisted.

[0080] (2) Ensure that the blind teeth on the blind tooth plate are precisely aligned with the A section of the pile leg to meet the meshing requirements of the platform lifting system.

[0081] IV. Precision Control Results Using the segmented manufacturing and assembly welding method of this embodiment, the accuracy control results of the pile shoes for Project N1063 are shown in Table 1 below: Table 1 shows the accuracy control results of the pile shoes in Project N1063.

[0082] [Comparative Example 1] Traditional Non-Reverse Deformation Pre-control Process The same N1063 pile shoe structure, welding materials and welding parameters as in this embodiment are used. The only difference is that the anti-deformation pre-control when the base plate sits on the tire is cancelled (no 10mm anti-deformation is added at the four corners). The rest of the process is the same.

[0083] Results: After segmented demolding, the four corners of the base plate exhibited springback deformation of 8-12mm, and there were 4 instances of levelness exceeding the tolerance, requiring large-area flame straightening. Even after straightening, 3mm of residual stress still caused springback. During blind tooth plate insertion, the center deviation between the top plate and the base plate reached 18mm, preventing the blind tooth plate from being inserted smoothly. The top plate needed to be forcibly trimmed, generating assembly stress.

[0084] [Comparative Example 2] Precision monitoring is available, but there are no work area-level stop points. The same welding parameters and monitoring frequency as in this embodiment are used, but the work area-level stop point in step S2 is cancelled (after the inner cladding is assembled, no pre-welding fine control inspection report is submitted, and welding is carried out directly).

[0085] Results: After welding, the verticality deviation of the inner endplate reached 6mm, and the deviation of the end reference edge reached 4mm, exceeding the allowable range. Since welding was already completed, the thick plate structure was difficult to correct, leading to difficulties in the subsequent insertion of blind tooth pieces and a decrease in overall accuracy.

[0086] [Comparative Example 3] There was a molting process but no free state measurement. The same welding sequence as in this embodiment is used, but in step S6, the sealing point is not removed. Precision measurement is performed directly under the constraint of the jig frame and a report is issued. Then the jig is removed directly.

[0087] Result: After the segmented removal from the mold, the structure was released from its constraints and deformed. The levelness deviation changed from "qualified" during measurement to "out of tolerance" (deviation reached 7mm) after removal, resulting in "false accuracy". Rework and correction were required after removal, delaying the project by 5 days.

[0088] [Comparative Example 4] Direct insertion of blind teeth without trimming process The same welding sequence as in this embodiment is adopted, but the "center verification and trimming of the top plate blind tooth piece" is cancelled in step S4. After the main body is welded, the blind tooth piece is directly inserted.

[0089] Results: During blind tooth plate insertion, the center of the top plate blind tooth plate deviated from the center of the bottom plate blind tooth plate by 15mm, making it impossible for the blind tooth plate to be positioned correctly. Forced insertion caused interference between the blind tooth plate and the top plate, resulting in localized plastic deformation and assembly stress. After welding, the twist angle of the blind tooth plate reached 1.8°, exceeding the allowable range (≤0.5°), requiring the blind tooth plate to be removed and reinstalled.

[0090] [Effect Analysis] The above embodiments and comparative examples show that: (1) The “anti-deformation pre-control + graded manufacturing” method of the present invention, through the systematic pre-setting of anti-deformation in the design stage of the jig, makes the welding springback and the pre-setting anti-deformation cancel each other out, thus fundamentally controlling the deformation direction.

[0091] (2) The setting of work area-level stop points is an important technical feature of the present invention. It forces inspection at key process nodes to ensure that deviations are detected and corrected before welding, and avoids accumulation to the point of no return.

[0092] (3) "Pre-demolition free state measurement" eliminates "constraint false accuracy", and the measurement data reflects the true residual deformation, avoiding rework after demolition.

[0093] (4) The "pre-insertion trimming" process ensures the smooth insertion and precise positioning of the blind tooth pieces, avoiding assembly stress and precision loss caused by forced assembly.

[0094] (5) The above technical features are interconnected and work together to achieve the technical effect of high-precision installation of blind teeth. The lack of any one feature will lead to a significant decrease in the effect.

[0095] Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those embodiments or examples, without contradiction. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for manufacturing and assembling a self-elevating offshore platform pile shoe, wherein the pile shoe is composed of four sections: SC0*A, SC0*B, SC0*C, and SC0*E, wherein the SC0*E section has blind teeth that connect with section A of the pile leg, characterized in that... The manufacturing and assembly welding of the SC0*E segment includes the following steps: S1. Base Plate Welding and Anti-Deformation Pre-control: The base plate is welded into a whole in sections. The base plate is mounted on a jig. During the jig fabrication, a downward anti-deformation amount is pre-set at the triangular part of the base plate. The center position point of the pile shoe, the longitudinal and transverse baselines and the 120° radial angle line are marked, and permanent punch points are set. During the welding process, the deviation of the center line, the 120° azimuth line and the edge line are monitored in real time. After welding, the plumb line is used to check the fit between the spliced ​​plate and the ground line. If there is a deviation, it is corrected and adjusted to establish a horizontal reference closed loop. S2. Mid-assembly welding of pile core and inner circumference plate and second precision closed-loop control: First, weld and hoist the pile core on the base plate, use a plumb bob to position the pile core, and confirm that it is aligned with the center of the pile shoe on the base plate; hoist the inner circumference plate, confirm the verticality of the inner circumference plate and the end difference with the base plate, the alignment of the longitudinal and transverse reference lines ≤ ±3mm, and the end difference reference edge ≤ ±2mm; add work area-level stop points, and submit a pre-welding precision control inspection report after the inner circumference plate is assembled. Welding can only be carried out after all out-of-tolerance parts have been rectified and re-inspected and qualified; establish a radial reference closed loop, and complete the mid-assembly welding in the order from the inside to the outside; S3. Segmented main body welding and process monitoring: When welding the segmented main body, follow the WPS welding process. During the welding process, monitor and measure the deviation of the 120° baseline and longitudinal and transverse baselines of the pile shoe from the ground sample line every hour. If the deviation exceeds ±2mm, stop welding immediately and adjust the welding sequence before resuming construction. Monitor the deviation of the segmented baseline relative to the ground sample and the height baseline of the outer plate every two hours. S4. Precision verification and trimming before blind tooth plate insertion: After the main body of the segment is welded and before the blind tooth plate is inserted, use a total station to find the theoretical position of the center of the blind tooth plate on the top plate of the pile shoe, make a cross auxiliary tool and tap the cross punch point, use a plumb bob to verify the deviation between the center of the blind tooth plate on the top plate and the center of the blind tooth plate on the bottom plate, and trim the top plate and internal radial plate of the pile shoe according to the verified deviation to ensure that the blind tooth plate is successfully inserted into the theoretical position; S5. Blind tooth plate insertion and post-weld inspection: After the blind tooth plate is inserted, the projected length and the torsion angle of the blind tooth plate are inspected before and after welding to ensure that the blind tooth plate is installed in place to meet the tolerance; after the special material structure around the blind tooth plate is welded, hydrogen removal treatment is performed, and after hydrogen removal, it is covered with heat insulation cotton for slow cooling and then inspected according to the requirements. S6. Segmented removal of the mold and post-weld free state precision control: After the main body of the segment is welded and before the overall completion of the mold removal, the sealing points are removed to put the segment in a free state for 100% self-inspection; the precision control personnel issue a post-weld precision control report. Before the mold removal, all parts with out-of-tolerance horizontality and verticality must be rectified and re-inspected and qualified before the mold removal can be carried out. The overall assembly phase includes the following steps: S7. Segmented installation and ground sampling line positioning: Draw ground sampling lines in the dock, including longitudinal and transverse reference ground sampling lines, 120° angle lines, and outer contour lines of the closure opening; arrange steel piers and control the levelness of the pier surface; install SC0*E segments first, and use a three-dimensional positioning trolley and plumb bob for positioning to meet the requirement of ±2mm level of the upper opening of the three blind teeth, the alignment deviation between the 120° angle line of the ground sampling and the 120° angle reference line on the segment is ≤2mm, and the deviation of the line connecting the centers of the blind tooth pieces is ≤5mm; S8. Joint Welding and Overall Precision Monitoring: Segments SC0*A, SC0*B, and SC0*C are hoisted sequentially, and a 3D trolley is used for positioning to control the horizontal deviation of the outer side plate height baseline, the joint spacing, and the deviation from the longitudinal and transverse ground reference lines. After the four segments are positioned and assembled, the overall precision control is reported for inspection. After passing the inspection, the joint welding is performed according to WPS. During the welding process, the deviation of the 120° angle line is monitored at all times. If it exceeds ±2mm, welding is stopped immediately and the welding sequence is adjusted. S9. Secondary fine-tuning after the construction of the cofferdam and the fixed pile frame: After the construction of the cofferdam and the fixed pile frame is completed and the first pile leg is hoisted, the pile shoe is fine-tuned again using a three-dimensional trolley to ensure the precise connection between the blind teeth on the blind tooth plate and the pile leg section A.

2. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: The reverse deformation amount mentioned in step S1 is 10mm downward, corresponding to an angle of 0.06°.

3. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: In step S2, the verticality of the pile core is ≤3mm, and the end difference of the non-reference edge is ≤±4mm.

4. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: The assembly welding sequence described in step S2 is as follows: first, weld the connecting weld between the inner circumference plate and the bottom plate; then, weld the connecting weld between the ring rib plate and the inner circumference plate; and finally, weld the butt weld between the outer circumference plate.

5. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: The monitoring and measurement described in step S3 includes: using a plumb bob to monitor the deviation of the segmented baseline relative to the ground sample, using a leveling instrument to monitor the height of the segmented outer plate reference sample, and creating a data table to record the dimensional monitoring of the pile shoe welding process.

6. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: The accuracy requirements for the blind tooth plate detection in step S5 are as follows: projection length L1=L2=L3=9500±8mm; |L1-L2|, |L2-L3|, |L3-L1|≤5mm; twist angle=60°≤0.5°.

7. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: In step S6, the 100% self-inspection items include: overall level, main dimensions, end difference, baseline deviation, verticality, pile shoe center and cylinder position deviation.

8. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: In step S7, the surface level of the pier is controlled to be ±2mm, and the BL3000mm horizontal reference line is used to adjust the level for coarse positioning.

9. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: In steps S1, S2, S3, and S8, the welding is performed using CO2 gas shielded welding or submerged arc welding, with a preheating temperature of 80–150°C and an interpass temperature of 120–200°C.

10. The method for manufacturing and assembling the self-elevating offshore platform pile shoe according to claim 1, characterized in that: After the pile shoe is manufactured, the deviation of the 120° angle line of the pile shoe is ≤2mm, the deviation of the center line of the blind tooth piece is ≤5mm, the twist angle of the blind tooth piece is ≤0.5°, and the success rate of the blind tooth piece insertion on the first attempt is ≥95%.

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