Method for determining and correcting tube joint weight and buoyancy center position of variable cross-section immersed tube

Abstract

The invention discloses a method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube joint, which aims at a special variable cross-section immersed tube joint structure, can standardly calculate the weight and buoyancy center position of the variable cross-section immersed tube joint, and further reasonably determines the fixed inclination height of the tube joint and controls the stability of the tube joint under various working conditions by determining the weight and buoyancy center position. And the safety and the stability of floating transportation in water saving of the variable-cross-section immersed tube are ensured. According to the method, the stress and deviation correction problems of the variable cross-section immersed tube joint in the floating and floating transportation processes are solved, the design difficulty is effectively reduced, and the construction control risk is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of immersed tube tunnels, in particular to a method for determining and correcting the section weight and buoyancy center position of an immersed tube with a variable cross-section. Background Art

[0002] Immersed tube tunnels have to go through a lot of complex underwater operations, including floating, sinking, docking, etc. The loads, combined effects, and construction conditions at each stage are very different from those of other tunnel construction methods. Due to the effects of water flow and construction loads at different stages, the force process is a dynamic change process.

[0003] There is relatively mature experience available for the floating, transporting and sinking of straight and large radius pipe sections with equal cross-sections, and the construction difficulty is relatively low and the risk is small. However, for variable cross-section pipe sections, their characteristics are as follows:

[0004] 1. The particularity of variable cross-section pipe sections

[0005] Cross-section change: The cross-section width of the variable cross-section pipe section is not constant, but gradually changes along the length direction. This change makes the stress situation of the pipe section during floating complicated.

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

[0007] Complex fluid dynamic characteristics: Variable-section pipe segments will be affected by various fluid dynamics such as water flow and waves during the floating process. The points of action and magnitude of these forces will change with the changes in the cross-section of the pipe segment, further increasing the risk of capsizing of the pipe segment.

[0008] 2. Analysis of the causes of capsizing

[0009] Fluid dynamic imbalance: When a variable-section pipe segment is subjected to uneven fluid dynamics during floating, such as one side being subjected to greater water flow impact or wave force while the other side is subjected to less force or no force, it will cause the pipe segment to generate an overturning moment.

[0010] Center of gravity shift: Since the center of gravity and the center of buoyancy of the pipe section do not coincide, when the pipe section is subjected to external forces (such as water flow, waves, wind, etc.), the center of gravity is easily shifted, thereby causing the pipe section to capsize.

[0011] Improper operation: During the floating process, improper operation (such as towing too fast, turning too sharply, etc.) may easily cause the pipe section to lose balance and capsize.

[0012] In physics, the center of gravity is the point of action of the resultant force of gravity on all parts of an object, while the center of buoyancy is the intersection of the lines of action of the buoyancy when the object is subjected to 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 changes in their cross-sectional shape and size. When the difference between the center of gravity and the center of buoyancy is large, the pipe section is prone to tilt or roll when subjected to external forces, thus affecting its stability and normal operation. Therefore, when designing and installing variable cross-section pipe sections, the differences in their centers of gravity and buoyancy must be fully considered, and accurate calculations and corrections must be performed. Specifically, this can be done through the following steps:

[0013] 1. Accurate measurement and calculation: First, it is necessary to accurately measure each section of the variable cross-section pipe segment, including its size, shape, weight and other parameters. Then, the center of gravity and buoyancy of the pipe segment are calculated using the principles of physics. This step is the basis for subsequent calculations and deviation correction.

[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 means that the pipe section is prone to tilt or roll when subjected to external forces. At this time, appropriate measures need to be taken to reduce this difference.

[0015] 3. Formulate a correction plan: According to the analysis results of the difference in gravity and buoyancy, formulate a specific correction plan. The correction plan may include changing the shape, size, weight distribution and other parameters of the pipe segment to adjust the position of its center of gravity and buoyancy. At the same time, you can also consider installing a support structure on the pipe segment or adjusting its installation method to increase its stability.

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

[0017] 5. Testing and verification: After the implementation of the corrective measures, testing and verification work is required. By simulating the stress conditions under actual working conditions, check whether the stability and operation effect of the pipe joint meet the requirements. If problems or deficiencies are found, timely adjustments and improvements need to be made.

[0018] In summary, variable cross-section pipe sections require more calculation and correction because of the large difference in gravity and buoyancy centers. Through accurate measurement and calculation, analysis of gravity and buoyancy center differences, formulation 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-section pipe segments, the cross-sectional characteristics change along the longitudinal direction, and the position of the buoyancy center and the center of gravity are difficult to determine and control, which can easily cause the pipe segment to tilt laterally in the water and produce a negative fixed tilt height. If the tilt continues to exceed a certain angle, it is difficult to ensure the stability of the pipe segment, and the buoyancy center and the center of gravity of the pipe segment need to be corrected. Since the buoyancy center of the pipe segment is determined by its horizontal projection center, and the center of gravity is calculated based on the load distribution on the pipe segment, the greater the difference in the cross-sectional area of ​​the ends of the variable-section pipe segment, the greater the deviation between its buoyancy center and the center of gravity, and the more significant the problem of pipe segment tilting, which increases the difficulty of design and also puts forward higher requirements for construction quality and risk control. In order to overcome the force and correction problems of variable-section submerged pipe segments during floating, transporting and sinking, a method for determining and correcting the weight and buoyancy center of variable-section submerged pipe segments is proposed. Summary of the invention

[0020] The purpose of the present invention is to provide a method for determining and correcting the weight and buoyancy center position of a variable-section immersed tube section, which can standardize the calculation of the weight and buoyancy center position of a variable-section immersed tube tunnel, reasonably determine the fixed inclination height of the section, and ensure that the section can remain stable under various conditions.

[0021] The present invention is achieved through the following technical solutions:

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

[0023] Step 1: Establish the plane form of immersed tube segments with different variable cross-sections;

[0024] Step 2: Use theoretical formulas to calculate the center of gravity and buoyancy of the variable-section immersed tube segment under different plane forms under the sealing walls on both sides;

[0025] Step 3: Use theoretical formulas to calculate the weight, buoyancy center spacing and unbalanced moment of the variable cross-section immersed tube segment;

[0026] Step 4: Determine the scheme for adjusting the position of the center of gravity based on the distance between the center of gravity and the center of buoyancy and the structural form of the variable-section immersed tube segment, and calculate the load arrangement method required to adjust the position of the center of gravity when the required moment is obtained to adjust the position of the center of gravity and the center of buoyancy to be consistent.

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

[0028] As a further improvement of the technical solution of the present invention, the positions of the gravity and buoyancy centers of different cross-sectional forms in step 2 are:

[0029] Form 1:

[0030] Center of buoyancy calculation formula:

[0031] When the component is axisymmetric G =0, Center of gravity calculation formula:

[0032] When the component is axisymmetric G =0,

[0033]

[0034] Where: H is the height of the pipe section structure (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 respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L3 and L4 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1 is the weight of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow variable cross-section; G4~G5 are the weights of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom;

[0035] Form 2:

[0036] Center of buoyancy calculation formula:

[0037] When the component is axisymmetric G =0,

[0038]

[0039] Center of gravity calculation formula:

[0040] When the component is axisymmetric G =0,

[0041]

[0042] Where: H is the height of the pipe structure (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 respectively; L1, L2, L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L4 and L5 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1 is the weight of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow variable cross-section; G4 is the weight of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom;

[0043] Form three:

[0044] Center of buoyancy calculation formula:

[0045] When the component is axisymmetricG =0,

[0046]

[0047] Center of gravity calculation formula:

[0048] When the component is axisymmetric G =0,

[0049]

[0050] Where: H is the height of the pipe section structure (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 respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L3 and L4 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1~G5 are the weights of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow equal cross-section; G4 is the weight of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom.

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

[0052] As a further improvement of the technical solution of the present invention, the balancing torque required in step 4 is considered to be the case where no additional volume is added to the variable-section immersed tube segment.

[0053] As a further improvement of the technical solution of the present invention, the correction method is to consider the uniform weight increase or pressurization mode of the internal, and the q distribution under the condition of uniform weight over the entire length on the other side of the buoyancy center is 2G 总 ΔxG / L 2 , L is the total length from the buoyancy center to the other side of the sealing wall, at this time, the position of the gravity and buoyancy center is consistent; the correction method is considered to be F under concentrated load conditions G 总 ΔxG / distance between concentrated load and center of buoyancy.

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

[0055] The present invention is aimed at the special variable-section immersed tube segment structure, and can standardize the calculation of the gravity and buoyancy center position of the variable-section immersed tube tunnel. By determining the gravity and buoyancy center position, the fixed inclination height of the segment can be reasonably determined, and the stability of the segment under various working conditions can be controlled to ensure the safety and stability of the variable-section immersed tube segment floating in water. The present invention solves the problem of the force of the variable-section immersed tube segment during floating and floating, effectively reduces the design difficulty, and reduces the construction control risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a structural schematic diagram of a variable cross-section form of a variable cross-section immersed tube segment according to an embodiment of the present invention;

[0057] Figure 2 It is a schematic diagram of the structure of the second variable cross-section type of the variable cross-section immersed tube segment according to an embodiment of the present invention;

[0058] Figure 3 It is a schematic diagram of the three structures of the variable cross-section form of the variable cross-section immersed tube segment in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The exemplary 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 indications in the embodiments of the present invention (such as up, down, left, right, front, back, upper end, lower end, top, bottom...) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0061] In the present invention, unless otherwise clearly defined and limited, the term "connection" should be understood in a broad sense, for example, "connection" can be a fixed connection, a detachable connection, or an integral connection; 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 connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features; in addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0063] The following combination Figures 1 to 3The present invention is further described in detail. Currently, there is no standardized method for calculating the position of the gravity center of buoyancy for a variable cross-section immersed tube tunnel. For a uniform cross-section immersed tube tunnel, the plane position of the gravity center of buoyancy is consistent, while the position of the gravity center of buoyancy of a variable cross-section immersed tube segment is inconsistent or the deviation is too large, which will lead to an eccentric moment causing the segment to overturn. Therefore, it is very necessary to confirm this eccentric moment and adjust the position of the gravity center of buoyancy.

[0064] The caisson fixed tilt height refers to the height at which the caisson tilts horizontally to one side when the pipe segment is in operation, until the liquid exceeds the side wall and enters the stable position on the outside. In the process of pipe segment design and operation, it is very important to understand and control the caisson fixed tilt height, because it directly affects the stability and safety of the pipe segment.

[0065] The importance of the caisson fixed inclination height is that it directly affects the stability of the pipe segment. When the pipe segment tilts, the liquid in the caisson will tilt outward, and the pressure will be unbalanced, resulting in unstable operation of the pipe segment. If the caisson fixed inclination height is too low, it will affect the safety and stability of the pipe segment. Designers need to reasonably determine the caisson fixed inclination height to ensure that the pipe segment can remain stable under various conditions. In summary, for special variable-section submerged pipe segment structures, it is very necessary to determine the deviation between the center of gravity and the fixed inclination height and adjust the center of gravity.

[0066] See also Figures 1 to 3 The present invention provides a technical solution: a method for determining and correcting the weight and buoyancy center position of a variable-section immersed tube, comprising the following steps:

[0067] Step 1: Establish the plane form of immersed tube segments with different variable cross-sections;

[0068] Step 2: Use theoretical formulas to calculate the center of gravity and buoyancy of the variable-section immersed tube segment under different plane forms under the sealing walls on both sides;

[0069] Step 3: Use theoretical formulas to calculate the weight, buoyancy center spacing and unbalanced moment of the variable cross-section immersed tube segment;

[0070] Step 4: Determine the scheme for adjusting the center of gravity position according to the distance between the center of gravity and the center of buoyancy and the structure of the variable-section immersed tube segment, and calculate the load arrangement method required to adjust the center of gravity position when the moment required to adjust the center of gravity and the center of buoyancy position is consistent;

[0071] Step 5: Use the theoretical formula to calculate the fixed inclination height of the variable cross-section immersed tube segment.

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

[0073] Reference Figure 1Specifically, in this embodiment, the positions of the gravity center of different cross-sectional forms in step 2 are:

[0074] Form 1:

[0075] Center of buoyancy calculation formula:

[0076] When the component is axisymmetric G =0,

[0077] Center of gravity calculation formula:

[0078] When the component is axisymmetric G =0,

[0079]

[0080] Where: H is the height of the pipe section structure (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 respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L3 and L4 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1 is the weight of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow variable cross-section; G4~G5 are the weights of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom;

[0081] Form 2: Figure 2 As shown,

[0082] Center of buoyancy calculation formula:

[0083] When the component is axisymmetric G =0,

[0084]

[0085] Center of gravity calculation formula:

[0086] When the component is axisymmetric G =0,

[0087]

[0088] Where: H is the height of the pipe structure (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 respectively; L1, L2, L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L4 and L5 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1 is the weight of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow variable cross-section; G4 is the weight of the bottom section at the other end; yG , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom;

[0089] Form 3: Figure 3 As shown,

[0090] Center of buoyancy calculation formula:

[0091] When the component is axisymmetric G =0,

[0092]

[0093] Center of gravity calculation formula:

[0094] When the component is axisymmetric G =0,

[0095]

[0096] Where: H is the height of the pipe section structure (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 respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L3 and L4 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1~G5 are the weights of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow equal cross-section; G4 is the weight of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom.

[0097] Specifically, in this embodiment, the unbalanced moments of the weight and buoyancy center distances of different cross-sectional forms in step 3 are Δx respectively. G With G 总 ΔxG.

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

[0099] Specifically, in this embodiment, the correction method is to consider the uniform weight increase or pressurization mode of the internal part, and the q distribution under the condition of uniform weight over the entire length on the other side of the buoyancy center is 2G. 总 ΔxG / L 2 , L is the total length from the buoyancy center to the other side of the sealing wall, at this time, the position of the gravity and buoyancy center is consistent; the correction method is considered to be F under concentrated load conditions G 总 ΔxG / distance between concentrated load and center of buoyancy.

[0100] Reference Figure 1Specifically, in this embodiment, the calculation formula of the fixed tilt height in step 5 is:

[0101]

[0102] H is the height of the pipe section structure (m); H1 is the thickness of the anti-anchor layer (m); h is the freeboard value (m); B1 and B2 are the diameters of the two ends of the variable-section immersed tube segment; L1 and L2 are the axial lengths of different sections of the variable-section immersed tube segment; H f is the distance between the buoyancy center and the gravity center of the pipe section (m), H wdl is the fixed inclination height (m), the center of gravity of the pipe section is above the center of buoyancy; under the premise that the inclination of the pipe section is less than 10°, the freeboard height can be calculated by the following formula:

[0103]

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

[0105] Form 2: Figure 2 As shown,

[0106]

[0107] Where: H is the height of the pipe structure (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. 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-section immersed tube segment respectively; L1, L2, and L3 are the axial lengths of different sections of the variable-section immersed tube segment respectively.

[0110] Compared with the existing technology, the present invention has the following beneficial effects:

[0111] The present invention is aimed at the special variable-section immersed tube segment structure, and can standardize the calculation of the gravity and buoyancy center position of the variable-section immersed tube tunnel. By determining the gravity and buoyancy center position, the fixed inclination height of the segment can be reasonably determined, and the stability of the segment under various working conditions can be controlled to ensure the safety and stability of the variable-section immersed tube segment floating in water. The present invention solves the problem of the force of the variable-section immersed tube segment during floating and floating, effectively reduces the design difficulty, and reduces the construction control risk.

[0112] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube, characterized in that: The following steps are involved: Step 1: Establish the plane form of immersed tube segments with different variable cross-sections; Step 2: Use theoretical formulas to calculate the center of gravity and buoyancy of the variable-section immersed tube segment under different plane forms under the sealing walls on both sides; Step 3: Use theoretical formulas to calculate the weight, buoyancy center spacing and unbalanced moment of the variable cross-section immersed tube segment; Step 4: Determine the scheme for adjusting the position of the center of gravity based on the distance between the center of gravity and the center of buoyancy and the structural form of the variable-section immersed tube segment, and calculate the load arrangement method required to adjust the position of the center of gravity when the required moment is obtained to adjust the position of the center of gravity and the center of buoyancy to be consistent.

2. A method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 1, characterized in that: In the step 1, the plane forms of the different variable cross-section immersed tube segments are respectively equal cross-section-variable cross-section form, equal cross-section-variable cross-section form and variable cross-section-equal cross-section form.

3. The method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 1, characterized in that: The positions of the gravity center of buoyancy of different cross-section forms in step 2 are: Form 1: Center of buoyancy calculation formula: When the component is axisymmetric G =0, Center of gravity calculation formula: When the component is axisymmetric G =0, Where: H is the height of the pipe section structure (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 respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L3 and L4 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1 is the weight of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow variable cross-section; G4~G5 are the weights of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom.

4. A method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 1, characterized in that: The positions of the gravity center of buoyancy of different cross-section forms in step 2 are: Form 2: Center of buoyancy calculation formula: When the component is axisymmetric G =0, Center of gravity calculation formula: When the component is axisymmetric G =0, Where: H is the height of the pipe structure (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 respectively; L1, L2, L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L4 and L5 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1 is the weight of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow variable cross-section; G4 is the weight of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom.

5. The method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 1 is characterized by: The positions of the gravity center of buoyancy of different cross-section forms in step 2 are: Form three: Center of buoyancy calculation formula: When the component is axisymmetric G =0, Center of gravity calculation formula: When the component is axisymmetric G =0, Where: H is the height of the pipe section structure (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 respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; L3 and L4 are the bottom widths of the two ends of the variable cross-section immersed tube segment respectively; G1~G5 are the weights of the bottom section at one end; G2 is the weight of the hollow equal cross-section; G3 is the weight of the hollow equal cross-section; G4 is the weight of the bottom section at the other end; y G , z G , x G are the horizontal axis, vertical axis and height above the vertical bottom.

6. A method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 1, characterized in that: In step 3, the unbalanced moments of the weight and buoyancy center distance of different cross-sectional forms are Δx G With G 总 ΔxG.

7. A method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 1, characterized in that: The balancing moment required in step 4 is considered to be the case where no additional volume is added to the variable-section immersed tube segment.

8. A method for determining and correcting the weight and buoyancy center position of a variable cross-section immersed tube according to claim 7, characterized in that: The correction method is to consider the uniform weight increase or pressurization mode on the inside, and the q distribution under the condition of uniform weight over the entire length on the other side of the buoyancy center is 2G. 总 ΔxG / L 2 , L is the total length from the buoyancy center to the other side of the sealing wall, at this time, the position of the gravity and buoyancy center is consistent; the correction method is considered to be F under concentrated load conditions G 总 ΔxG / distance between concentrated load and center of buoyancy.

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