Method for determining and correcting the position of the center of gravity and the center of buoyancy of a variable cross-section immersed tube segment

Abstract

The application discloses a method for determining and rectifying the position of a heavy center and a floating center of a variable cross-section immersed tube segment, and can standardize the calculation of the position of the heavy center and the floating center of the variable cross-section immersed tube segment according to the special structure of the variable cross-section immersed tube segment, and further reasonably determine the inclination height of the segment by determining the position of the heavy center and the floating center, so as to control the stability of the segment under various working conditions and ensure the safety and stability of the variable cross-section immersed tube segment during the floating operation in water. The application overcomes the stress and rectification problems of the variable cross-section immersed tube segment during the lifting and floating operation, effectively reduces the design difficulty and reduces the construction control risk.

Description

Technical Field

[0001] This invention relates to the field of immersed tunnel technology, and in particular to a method for determining and correcting the position of the weight and buoyancy center of a variable cross-section immersed tunnel segment. Background Technology

[0002] Immersed tunnels involve numerous complex underwater operations, including floating, sinking, and docking. The loads, combined effects, and construction conditions at each stage differ significantly from other tunnel construction methods. Due to the influence of water flow forces and construction loads at different stages, the stress process is a dynamic and changing process.

[0003] There is already relatively mature experience to draw upon for the lifting, floating, and sinking of straight and large-radius curved pipe sections with uniform cross-sections, and the construction difficulty and risk are relatively low. However, for pipe sections with variable cross-sections, the characteristics are as follows:

[0004] I. Special characteristics of variable cross-section pipe sections

[0005] Cross-sectional variation: The cross-sectional width of the variable cross-section pipe section is not constant, but gradually changes along its length. This variation complicates the stress situation of the pipe section during floating.

[0006] Asymmetry between center of gravity and center of buoyancy: Due to the change in cross-sectional width, the longitudinal and transverse centers of gravity and center of buoyancy of the variable cross-section pipe section often do not coincide, which increases the instability of the pipe section during the floating process.

[0007] Complex hydrodynamic characteristics: During the floating process, the variable cross-section pipe section is subjected to various hydrodynamic forces such as water flow and waves. The point of application and magnitude of these forces will change with the change of the pipe section cross-section, further increasing the risk of the pipe section overturning.

[0008] II. Analysis of the Causes of Overturning

[0009] Hydrodynamic imbalance: When a variable cross-section pipe section is subjected to uneven hydrodynamic forces during floating, such as one side being subjected to a large water flow impact force or wave force, while the other side is subjected to a smaller force or no force, it will cause the pipe section to generate an overturning moment.

[0010] Center of gravity shift: Due to the misalignment of the center of gravity and the center of buoyancy of the pipe section, when the pipe section is subjected to external forces (such as water flow, waves, wind, etc.), the center of gravity is prone to shift, which in turn causes the pipe section to overturn.

[0011] Improper operation: During the floating process, improper operation (such as excessive towing speed or sharp turning) can easily cause the tunnel section to lose balance and capsize.

[0012] In physics, the center of gravity is the point of application of the resultant force of gravity acting on all parts of an object, while the center of buoyancy is the intersection of the lines of action of buoyancy when an object experiences buoyancy in a fluid. For variable cross-section pipe sections, the positions of their center of gravity and center of buoyancy will change accordingly due to variations in their cross-sectional shape and size. When the difference between the center of gravity and the center of buoyancy is significant, the pipe section is prone to tilting or rolling under external forces, thus affecting its stability and normal operation. Therefore, when designing and installing variable cross-section pipe sections, the difference in their center of gravity and center of buoyancy must be fully considered, and accurate calculations and corrections must be performed. Specifically, this can be done through the following steps:

[0013] 1. Precise Measurement and Calculation: First, precise measurements of each section of the variable cross-section pipe section are required, including its dimensions, shape, weight, and other parameters. Then, the positions of the pipe section's center of gravity and center of buoyancy are calculated using principles of physics. This step forms the basis for subsequent calculations and corrections.

[0014] 2. Analyze the difference between the center of gravity and the center of buoyancy: After obtaining the positions of the center of gravity and the center of buoyancy, it is necessary to analyze the difference between them. If the difference is large, it indicates that the pipe section is prone to tilting or rolling when subjected to external forces. In this case, corresponding measures need to be taken to reduce this difference.

[0015] 3. Develop a correction plan: Based on the analysis results of the difference between the center of gravity and the center of buoyancy, develop a specific correction plan. The correction plan may include changing parameters such as the shape, size, and weight distribution of the pipe section to adjust the position of its center of gravity and center of buoyancy. Simultaneously, installing support structures on the pipe section or adjusting its installation method may also be considered to increase its stability.

[0016] 4. Implement corrective measures: After developing the corrective action plan, it needs to be implemented according to the plan's requirements. During implementation, attention must be paid to safety and quality issues to ensure the effectiveness and reliability of the corrective measures.

[0017] 5. Testing and Verification: After the corrective measures are implemented, testing and verification are required. By simulating the stress conditions under actual working conditions, the stability and operational performance of the pipe section are verified to ensure they meet the requirements. If any problems or deficiencies are found, adjustments and improvements need to be made promptly.

[0018] In summary, variable cross-section pipe sections require more calculation and correction due to the significant difference in their center of gravity. Through precise measurement and calculation, analysis of the differences in center of gravity, development of correction plans, implementation of correction measures, and testing and verification, the stability and normal operation of variable cross-section pipe sections can be ensured.

[0019] However, for variable cross-section pipe sections, the cross-sectional characteristics change longitudinally, making it difficult to determine and control the positions of the center of buoyancy and center of gravity. This easily causes the pipe section to tilt laterally in the water, resulting in a negative constant tilt height. If the tilt continues beyond a certain angle, it is difficult to ensure the stability of the pipe section, requiring correction of the center of buoyancy and center of gravity. Since the center of buoyancy of the pipe section is determined by its horizontal projection center, and the center of gravity is calculated based on the load distribution on the pipe section, the greater the difference in cross-sectional area between the two ends of the variable cross-section pipe section, the greater the deviation between its center of buoyancy and center of gravity, and the more significant the tilting problem becomes. This increases the design difficulty and also places higher demands on construction quality and risk control. To overcome the stress and correction problems of variable cross-section immersed tunnel sections during lifting, floating, and sinking, a method for determining and correcting the positions of the center of gravity and center of buoyancy of variable cross-section immersed tunnel sections is proposed. Summary of the Invention

[0020] The purpose of this invention is to provide a method for determining and correcting the position of the center of gravity and buoyancy of a variable cross-section immersed tunnel segment. This method can standardize the calculation of the position of the center of gravity and buoyancy of the variable cross-section immersed tunnel, reasonably determine the constant tilt height of the segment, and ensure that the segment remains stable under various conditions.

[0021] This invention is achieved through the following technical solution:

[0022] A method for determining and correcting the position of the weight and buoyancy center of a variable cross-section immersed tunnel section, comprising the following steps:

[0023] Step 1: Establish the planar form of immersed tunnel sections with different cross-sections;

[0024] Step 2: Calculate the position of the center of gravity and center of buoyancy of the variable cross-section immersed tunnel section under different planar forms under the two side sealing walls using theoretical formulas;

[0025] Step 3: Calculate the weight, buoyancy center distance, and unbalanced moment of the variable cross-section immersed tunnel section using theoretical formulas;

[0026] Step 4: Based on the distance between the center of gravity and the center of buoyancy and the structural form of the variable cross-section immersed tube section, determine the scheme for adjusting the position of the center of gravity, and calculate the load arrangement method required to adjust the position of the center of gravity when the required torque for adjusting the positions of the center of gravity to be consistent.

[0027] As a further improvement to the technical solution of the present invention, the planar forms of the immersed tube sections with different variable cross-sections in step 1 are respectively equal cross-section-variable cross-section, equal cross-section-variable cross-section-equal cross-section and variable cross-section-equal cross-section.

[0028] As a further improvement to the technical solution of the present invention, the positions of the buoyancy centers for different cross-sectional shapes in step 2 are as follows:

[0029] Format 1:

[0030] Formula for calculating the center of buoyancy:

[0031] When the component is axially symmetric, y G =0, Formula for calculating center of gravity:

[0032] When the component is axially symmetric, y G =0,

[0033]

[0034] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1 and L2 are the axial lengths of different sections of the variable cross-section immersed tunnel section, respectively; L3 and L4 are the bottom sealing widths of the two ends of the variable cross-section immersed tunnel section, respectively; G1 is the gravity of the bottom sealing section at one end; G2 is the gravity of the hollow constant cross-section; G3 is the gravity of the hollow variable cross-section; G4 to G5 are the gravity of the bottom sealing section at the other end; y G , z G x G The x-axis, y-axis, and height above the vertical bottom surface;

[0035] Form Two:

[0036] Formula for calculating the center of buoyancy:

[0037] When the component is axially symmetric, y G =0,

[0038]

[0039] Formula for calculating center of gravity:

[0040] When the component is axially symmetric, y G =0,

[0041]

[0042] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tunnel section, respectively; L4 and L5 are the bottom sealing widths of the two ends of the variable cross-section immersed tunnel section, respectively; G1 is the gravity of the bottom sealing section at one end, G2 is the gravity of the hollow constant cross-section, G3 is the gravity of the hollow variable cross-section, G4 is the gravity of the bottom sealing section at the other end, and y G , z G x G The x-axis, y-axis, and height above the vertical bottom surface;

[0043] Form 3:

[0044] Formula for calculating the center of buoyancy:

[0045] When the component is axially symmetric, yG =0,

[0046]

[0047] Formula for calculating center of gravity:

[0048] When the component is axially symmetric, y G =0,

[0049]

[0050] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1 and L2 are the axial lengths of different sections of the variable cross-section immersed tunnel section, respectively; L3 and L4 are the bottom sealing widths of the two ends of the variable cross-section immersed tunnel section, respectively; G1 to G5 are the gravity of the bottom sealing section at one end, G2 is the gravity of the hollow constant cross-section, G3 is the gravity of the hollow constant cross-section, G4 is the gravity of the bottom sealing section at the other end, and y G , z G x G The x-axis, y-axis, and height above the vertical base are the coordinates.

[0051] As a further improvement to the technical solution of the present invention, in step 3, the unbalanced moments of the weight and buoyancy center distance for different cross-sectional shapes are respectively Δx G With G 总 ΔxG.

[0052] As a further improvement to the technical solution of the present invention, the required balancing torque in step 4 is considered to be in the case of not adding extra volume to the variable cross-section immersed tube section.

[0053] As a further improvement to the technical solution of this invention, the correction method is considered to be a uniform weight increase or pressurization mode inside, where the q distribution under the condition of uniform weight along the entire length on the other side of the buoyancy center is 2G. 总 ΔxG / L 2 L is the total length from the center of buoyancy to the sealing wall on the other side, at which point the positions of the re-buoyancy centers are consistent; the correction method is considered to be F = G under concentrated load conditions. 总 ΔxG / Distance between concentrated load and buoyancy center position.

[0054] The present invention has the following beneficial effects:

[0055] This invention addresses the unique variable cross-section immersed tunnel segment structure by providing a standardized calculation of the center of gravity (COP) location. Determining the COP location allows for the rational determination of the segment's tilt height, enabling control over segment stability under various operating conditions and ensuring the safety and stability of the variable cross-section immersed tunnel segment during underwater floating. This invention solves the stress problem of variable cross-section immersed tunnel segments during lifting and floating, effectively reducing design complexity and construction control risks. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of a variable cross-section immersed tube section according to an embodiment of the present invention.

[0057] Figure 2 This is a schematic diagram of the variable cross-section immersed tube section of the present invention, in the second form.

[0058] Figure 3 This is a schematic diagram of the three-structure variable cross-section immersed tube section according to an embodiment of the present invention. Detailed Implementation

[0059] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0060] It should be noted that all directional indicators (such as up, down, left, right, front, back, upper end, lower end, top, bottom, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0061] In this invention, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0063] The following combination Figures 1 to 3This invention will be further described in detail below. Currently, there is no standard method for calculating the position of the center of gravity for immersed tunnels with variable cross-sections. For immersed tunnels with constant cross-sections, the plane position of the center of gravity is consistent. However, for immersed tunnels with variable cross-sections, the position of the center of gravity is inconsistent or the deviation is too large, which can lead to eccentric moment and cause the tunnel section to overturn. Therefore, it is essential to confirm this eccentric moment and adjust the position of the center of gravity.

[0064] The caisson tilt height refers to the height at which the caisson tilts horizontally to one side until the liquid overflows the sidewall and enters the stable position on the outer side during tunnel section operation. Understanding and controlling the caisson tilt height is crucial in the design and operation of tunnel sections, as it directly affects the stability and safety of the tunnel sections.

[0065] The caisson's tilt height is crucial because it directly impacts the stability of the tunnel sections. When a tunnel section tilts, the liquid inside the caisson will flow outwards, creating a pressure imbalance and leading to instability in its operation. If the caisson's tilt height is too low, it will affect the safety and stability of the tunnel section. Designers need to determine the caisson's tilt height appropriately to ensure the tunnel section remains stable under various conditions. In summary, for special variable cross-section immersed tunnel sections, determining the position of the center of buoyancy and the tilt height, as well as adjusting the deviation between the center of buoyancy and the center of buoyancy, is essential.

[0066] Please see Figures 1 to 3 This invention provides a technical solution: a method for determining and correcting the position of the weight and buoyancy center of a variable cross-section immersed tunnel section, comprising the following steps:

[0067] Step 1: Establish the planar form of immersed tunnel sections with different cross-sections;

[0068] Step 2: Calculate the position of the center of gravity and center of buoyancy of the variable cross-section immersed tunnel section under different planar forms under the two side sealing walls using theoretical formulas;

[0069] Step 3: Calculate the weight, buoyancy center distance, and unbalanced moment of the variable cross-section immersed tunnel section using theoretical formulas;

[0070] Step 4: Based on the distance between the center of gravity and the center of buoyancy and the structural form of the variable cross-section immersed tube section, determine the scheme for adjusting the position of the center of gravity, and calculate the load arrangement method for adjusting the position of the center of gravity when the required torque for adjusting the positions of the center of gravity and the center of buoyancy is consistent.

[0071] Step 5: Calculate the constant tilt height of the variable cross-section immersed tube section using theoretical formulas.

[0072] Specifically, in this embodiment, the planar forms of the immersed tube sections with different variable cross-sections in step 1 are respectively equal cross-section-variable cross-section, equal cross-section-variable cross-section-equal cross-section, and variable cross-section-equal cross-section.

[0073] Reference Figure 1Specifically, in this embodiment, the positions of the buoyancy centers for different cross-sectional shapes in step 2 are as follows:

[0074] Format 1:

[0075] Formula for calculating the center of buoyancy:

[0076] When the component is axially symmetric, y G =0,

[0077] Formula for calculating center of gravity:

[0078] When the component is axially symmetric, y G =0,

[0079]

[0080] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1 and L2 are the axial lengths of different sections of the variable cross-section immersed tunnel section, respectively; L3 and L4 are the bottom sealing widths of the two ends of the variable cross-section immersed tunnel section, respectively; G1 is the gravity of the bottom sealing section at one end; G2 is the gravity of the hollow constant cross-section; G3 is the gravity of the hollow variable cross-section; G4 to G5 are the gravity of the bottom sealing section at the other end; y G , z G x G The x-axis, y-axis, and height above the vertical bottom surface;

[0081] Form 2: such as Figure 2 As shown,

[0082] Formula for calculating the center of buoyancy:

[0083] When the component is axially symmetric, y G =0,

[0084]

[0085] Formula for calculating center of gravity:

[0086] When the component is axially symmetric, y G =0,

[0087]

[0088] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tunnel section, respectively; L4 and L5 are the bottom sealing widths of the two ends of the variable cross-section immersed tunnel section, respectively; G1 is the gravity of the bottom sealing section at one end, G2 is the gravity of the hollow constant cross-section, G3 is the gravity of the hollow variable cross-section, G4 is the gravity of the bottom sealing section at the other end, and yG , z G x G The x-axis, y-axis, and height above the vertical bottom surface;

[0089] Form 3: such as Figure 3 As shown,

[0090] Formula for calculating the center of buoyancy:

[0091] When the component is axially symmetric, y G =0,

[0092]

[0093] Formula for calculating center of gravity:

[0094] When the component is axially symmetric, y G =0,

[0095]

[0096] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1 and L2 are the axial lengths of different sections of the variable cross-section immersed tunnel section, respectively; L3 and L4 are the bottom sealing widths of the two ends of the variable cross-section immersed tunnel section, respectively; G1 to G5 are the gravity of the bottom sealing section at one end, G2 is the gravity of the hollow constant cross-section, G3 is the gravity of the hollow constant cross-section, G4 is the gravity of the bottom sealing section at the other end, and y G , z G x G The x-axis, y-axis, and height above the vertical base are the coordinates.

[0097] Specifically, in this embodiment, the unbalanced torques of the weight and buoyancy center distance for different cross-sectional shapes in step 3 are Δx. G With G 总 ΔxG.

[0098] Specifically, in this embodiment, the required balancing torque in step 4 is considered to be for the case where no additional volume is added to the variable cross-section immersed tube section.

[0099] Specifically, in this embodiment, the correction method is considered to be a uniform weight increase or pressurization mode inside the buoyancy center, where the q distribution is 2G under the condition of uniform weight distribution along the entire length of the other side. 总 ΔxG / L 2 L is the total length from the center of buoyancy to the sealing wall on the other side, at which point the positions of the re-buoyancy centers are consistent; the correction method is considered to be F = G under concentrated load conditions. 总 ΔxG / Distance between concentrated load and buoyancy center position.

[0100] Reference Figure 1Specifically, in this embodiment, the formula for calculating the tilt height in step 5 is as follows:

[0101]

[0102] H is the structural height of the tunnel section (m); H1 is the adjustable thickness of the anti-anchoring layer (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tunnel section, respectively; H f H is the distance (m) between the center of buoyancy and the center of gravity of the pipe section. wdl For a fixed inclination height (m), the center of gravity of the pipe section is considered positive when it is above the center of buoyancy; provided the inclination of the pipe section is less than 10°, the freeboard height in the formula can be calculated using the following formula:

[0103]

[0104] Where: G k G represents the standard value of the pipe section's self-weight (kN); a The standard weight (kN) of the pipe section outfitting and temporary components; γ w water unit weight (kN / m) 3 S is the projected area of ​​the variable cross-section pipe section;

[0105] Form 2: such as Figure 2 As shown,

[0106]

[0107] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section, respectively; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tunnel section, respectively. Form 3: As shown Figure 3 As shown,

[0108]

[0109] In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tunnel section; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tunnel section.

[0110] Compared with existing technologies, the present invention has the following advantages:

[0111] This invention addresses the unique variable cross-section immersed tunnel segment structure by providing a standardized calculation of the center of gravity (COP) location. Determining the COP location allows for the rational determination of the segment's tilt height, enabling control over segment stability under various operating conditions and ensuring the safety and stability of the variable cross-section immersed tunnel segment during underwater floating. This invention solves the stress problem of variable cross-section immersed tunnel segments during lifting and floating, effectively reducing design complexity and construction control risks.

[0112] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining and correcting the position of the center of gravity and the center of buoyancy of a variable cross-section immersed tube segment, characterized in that, It comprises the following steps: Step 1: establishing the plane form of different variable cross-section immersed tube segments; the plane forms of different variable cross-section immersed tube segments are equal cross-section-variable cross-section form, equal cross-section-variable cross-section-equal cross-section form and variable cross-section-equal cross-section form respectively; Step 2: calculating the barycenter and the position of the center of buoyancy of the variable cross-section immersed tube segment under different plane forms considering the two side enclosing walls by using theoretical formula; Step 3: calculating the distance between the barycenter and the center of buoyancy and the unbalanced moment of the variable cross-section immersed tube segment by using theoretical formula; Step 4: according to the distance between the barycenter and the center of buoyancy and the structure form of the variable cross-section immersed tube segment, determining the scheme of regulating the position of the barycenter, and calculating the load arrangement mode of the barycenter position required for regulating the position of the barycenter required for the moment of balancing the barycenter and the center of buoyancy; The position of the barycenter and the center of buoyancy in step 2 is as follows: Form one is equal cross-section-variable cross-section form: The calculation formula of the center of buoyancy is: In the case of an axisymmetric component , , , The calculation formula of the barycenter is: In the case of axisymmetric components , In the formula: H is the structure height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of two ends of the variable cross-section immersed tube segment; L1 and L2 are the axial lengths of different cross sections of the variable cross-section immersed tube segment; L3 and L4 are the widths of the bottom sealing of two ends of the variable cross-section immersed tube segment; G1 is the gravity of the bottom sealing cross section at one end; G2 is the gravity of the hollow constant cross section; G3 is the gravity of the hollow variable cross section; G4 and G5 are the gravities of the bottom sealing cross section at the other end; y G , z G , x G are the horizontal coordinate, vertical coordinate and height above the vertical bottom surface; Form two is equal cross-section-variable cross-section-equal cross-section form: The calculation formula of the center of buoyancy is: In the case of axisymmetry of the component , , Center of gravity calculation formula: In the case of axisymmetric components , In the formula: H is the structure height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable cross-section immersed tube segment; L1, L2 and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment; L4 and L5 are the widths of the two ends of the variable cross-section immersed tube segment; G1 is the gravity of the one end of the bottom sealing cross-section; G2 is the gravity of the hollow equal cross-section; G3 is the gravity of the hollow variable cross-section; G4 is the gravity of the other end of the bottom sealing cross-section; y G , z G , x G are the horizontal coordinate, vertical coordinate and height above the vertical bottom surface; Form three is variable cross-section-equal cross-section form: The calculation formula of the center of buoyancy is: In the case of axisymmetry of the component , , Formula for calculating the center of gravity: In the case of axisymmetric components , In the formula: H is the structure height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters of two ends of the variable cross-section immersed tube segment; L1 and L2 are the axial lengths of different cross sections of the variable cross-section immersed tube segment; L3 and L4 are the widths of the bottom sealing of two ends of the variable cross-section immersed tube segment; G1-G5 are the gravities of the bottom sealing cross section at one end, G2 is the hollow equal cross-section gravity, G3 is the hollow equal cross-section gravity, G4 is the gravity of the bottom sealing cross section at the other end, y G , z G , x G are the horizontal coordinate, vertical coordinate and height above the vertical bottom surface; The different section form in step 3, the imbalance moment between the heavy center and the buoyancy center is Δx G With G 总 ΔxG; The correction mode considers the q distribution as 2G under the condition of uniform weight on the whole length of the other side of the buoyancy center under the internal uniform weight increase or pressure increase mode 总 ΔxG / L 2 L is the full length from the buoyancy center to the other side of the sealing wall, at which time the heavy buoyancy center position is consistent; the correction mode considers F as G under the concentrated load condition 总 ΔxG / concentrated load and the distance between the buoyancy center position 2. The method for determining and rectifying the position of the center of gravity and the center of buoyancy of a variable cross-section immersed tube segment according to claim 1, characterized in that: The required balancing moment in step 4 is considered as the case of not adding extra volume to the variable cross-section immersed tube segment.

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