A method for determining the metacentric height of a variable cross-section immersed tube segment

Abstract

The present invention discloses a method for determining the metacentric height of a variable cross-section immersed tube segment. Aiming at the special structure of the variable cross-section immersed tube segment, it can standardize the calculation of the metacentric height of the variable cross-section immersed tube segment. By determining the metacentric height of the tube segment, the stability of the tube segment under various working conditions can be controlled, ensuring the safety and stability of the variable cross-section immersed tube segment during floating transportation in water. The present invention solves the problem of the force on the variable cross-section immersed tube segment during floating and floating transportation, effectively reducing the design difficulty of the tube segment and the construction control risk.

Description

Technical Field

[0001] The present invention relates to the technical field of immersed tube tunnels, and particularly to a method for determining the metacentric height of a variable cross-section immersed tube segment. Background Art

[0002] Immersed tube tunnels involve a large number of complex underwater operations, including floating transportation, sinking, docking, etc. The acting loads, combined effects, and construction conditions in each stage are very different from other tunnel construction methods. Due to the action of water flow forces and construction loads at different stages, its stress process is a dynamic change process.

[0003] For the floating, floating transportation, and sinking processes of equal cross-section straight and large-radius curved pipe segments, there are relatively mature experiences for reference, and the construction difficulty is relatively low and the risk is small. However, for variable cross-section pipe segments, their characteristics are as follows:

[0004] I. Particularities of Variable Cross-Section Pipe Segments

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

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

[0007] Complex hydrodynamic characteristics: A variable cross-section pipe segment will be affected by various hydrodynamic forces such as water flow and waves during floating transportation. The acting points and magnitudes of these forces will change with the change of the pipe segment cross-section, further increasing the risk of the pipe segment capsizing.

[0008] II. Analysis of Capsizing Causes

[0009] Hydrodynamic imbalance: When a variable cross-section pipe segment is affected by uneven hydrodynamic forces during floating transportation, 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 segment to generate an overturning moment.

[0010] Center of gravity offset: Due to the non-coincidence of the center of gravity and the center of buoyancy of the pipe segment, when the pipe segment is subjected to external forces (such as water flow, waves, wind, etc.), the center of gravity is prone to offset, thereby triggering the capsizing of the pipe segment.

[0011] Improper operation: During floating transportation, if the operation is improper (such as too fast towing speed, too sharp turning, etc.), it is also easy to cause the pipe segment to lose balance and capsize.

[0012] However, for variable cross-section pipe segments, the cross-sectional characteristics vary longitudinally, and it is difficult to determine and control the positions of the center of buoyancy and the center of gravity, which can easily cause the pipe segment to tilt laterally in water and result in a negative metacentric height. If the tilt continues beyond a certain angle, it is difficult to ensure the stability of the pipe segment. The metacentric height of a immersed tube refers to the height when the immersed tube tilts horizontally to one side during operation until the liquid exceeds the side wall and enters the stable position on the outside. During the design and operation of the pipe section, it is very important to understand and control the metacentric height of the immersed tube because it directly affects the stability and safety of the pipe section. The definition and function of the metacentric height are as follows:

[0013] I. Definition and Function of Metacentric Height

[0014] The metacentric height refers to the height or distance at which an object can maintain a certain stable state when subjected to external forces. In the project of immersed tube tunnels, the metacentric height is closely related to the distance between the center of buoyancy and the center of gravity of the pipe segment. Increasing the metacentric height can reduce the risk of transverse tilt during the floating transportation of the pipe segment and improve the stability of the pipe segment.

[0015] II. Influence of Metacentric Height on Overturning Problems

[0016] Reducing the distance between the center of buoyancy and the center of gravity: By adjusting the design of the pipe segment and increasing its metacentric height, the distance between the center of buoyancy and the center of gravity of the pipe segment can be reduced. This helps to reduce the overturning moment generated when the pipe segment is subjected to external forces, thereby improving the anti-overturning ability of the pipe segment.

[0017] Improving the initial stability: Increasing the metacentric height can also improve the initial stability of the pipe segment, that is, the ability of the pipe segment to quickly return to a stable state when subjected to small external forces. This helps to reduce the transverse tilt phenomenon of the pipe segment during floating transportation due to slight disturbances.

[0018] In summary, determining the metacentric height is an effective means to alleviate the overturning problem of variable cross-section pipe sections during floating transportation. The importance of the metacentric height of the immersed tube lies in that it directly affects the stability of the pipe section. When the pipe section tilts laterally, the liquid inside the immersed tube will tilt outward, and at the same time, the pressure will become unbalanced, resulting in unstable operation of the pipe section. If the metacentric height of the immersed tube is too low, it will affect the safety and stability of the pipe section. Designers need to reasonably determine the metacentric height of the immersed tube to ensure that the pipe section can maintain stability under various conditions. There is no clear calculation method for the metacentric height to ensure the safety of floating transportation for variable cross-section pipe sections, nor is there a specification for calculating the metacentric height of immersed tube tunnels with variable cross-sections. In summary, for the special structure of variable cross-section immersed tube pipe sections, it is very necessary to determine the metacentric height. Therefore, a method for determining the metacentric height of variable cross-section immersed tube pipe sections is proposed. Summary of the Invention

[0019] The purpose of the present invention is to provide a method for determining the metacentric height of a variable cross-section immersed tube segment, which can standardize the calculation of the metacentric height of a variable cross-section immersed tube tunnel, reasonably determine the metacentric height of the immersed tube, and ensure the stability of the tube segment under various conditions.

[0020] The present invention is achieved through the following technical solutions:

[0021] A method for determining the metacentric height of a variable cross-section immersed tube segment, which includes the following steps:

[0022] Step 1: Establish the plane forms of different variable cross-section immersed tube segments; the plane forms of different variable cross-section immersed tube segments are respectively the equal cross-section - variable cross-section form, the equal cross-section - variable cross-section - equal cross-section form, and the variable cross-section - equal cross-section form;

[0023] Step 2: Calculate the metacentric height of the variable cross-section immersed tube segment using theoretical formulas;

[0024] Step 3: The metacentric height is divided into two aspects: no ballast water in the floating transportation stage and ballast water in the floating transportation stage. Further, as an improvement of the technical solution of the present invention, in the floating transportation stage: no ballast water:

[0025] Form 1: The calculation formula for the metacentric height in Step 2 is:

[0026]

[0027]

[0028] 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 at both 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; H f is the distance between the center of buoyancy and the center of gravity of the pipe section (m), H wdl is the metacentric height (m), and when the center of gravity of the pipe section is above the center of buoyancy, it is positive; on the premise that the inclination of the pipe section is less than 10°, the freeboard height in the formula can be calculated by the following formula:

[0029]

[0030] In the formula: G k is the standard value of the self-weight of the pipe section (kN); G a is the standard value of the weight of the outfitting and temporary components of the pipe section (kN); H 1 is the adjustment thickness of the anti-anchor layer (m); γ w is the unit weight of water (kN / m 3 ³), and S is the projected area of the variable cross-section pipe section;

[0031] Form 2:

[0032]

[0033] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both ends of the variable cross-section immersed tube segment respectively; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively.

[0034] Form Three:

[0035]

[0036] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both 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.

[0037] Form Four:

[0038]

[0039] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 is the diameter at one end of the variable cross-section immersed tube segment; B2 is the vertical height by which the other end of the variable cross-section immersed tube segment slopes downward based on the B1 diameter; B3 is the vertical height by which the other end of the variable cross-section immersed tube segment slopes upward based on the B1 diameter; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively.

[0040] Furthermore, as an improvement to the technical solution of the present invention, during the floating transportation stage: with ballast water:

[0041] Form One: The calculation formula for the metacentric height in step 2 is:

[0042]

[0043] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both 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; H f is the distance between the center of buoyancy and the center of gravity of the pipe section (m), H wdl is the metacentric height (m), ∑I W is the sum of the moments of inertia of the water surfaces of the ballast water in each part of the pipe section about their respective axes; it is positive when the center of gravity of the pipe section is above the center of buoyancy; the freeboard height can be calculated by the following formula:

[0044]

[0045] Where: G k is the standard value of the self-weight of the pipe section (kN); G a is the standard value of the weight of the outfitting and temporary components of the pipe section (kN); H 1 is the adjustment thickness of the anti-anchor layer (m); γw is the unit weight of water (kN / m 3 ), S is the projected area of the variable cross-section pipe segment;

[0046] Form 2:

[0047]

[0048]

[0049] Where: H is the structural height of the pipe segment (m); h is the freeboard value (m); B1 and B2 are the diameters at both ends of the variable cross-section immersed tube section respectively; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube section respectively, and ∑I W is the sum of the moments of inertia of the water surfaces of each part of the ballast water in the pipe segment about their respective axes;

[0050] Form 3:

[0051]

[0052]

[0053] In the formula: H is the structural height of the pipe segment (m); h is the freeboard value (m); B1 and B2 are the diameters at both ends of the variable cross-section immersed tube section respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube section respectively, and ∑I W is the sum of the moments of inertia of the water surfaces of each part of the ballast water in the pipe segment about their respective axes;

[0054] Form 4:

[0055]

[0056] In the formula: H is the structural height of the pipe segment (m); h is the freeboard value (m); B1 is the diameter at one end of the variable cross-section immersed tube section; B2 is the vertical height by which the other end of the variable cross-section immersed tube section slopes downward based on the B1 diameter; B3 is the vertical height by which the other end of the variable cross-section immersed tube section slopes upward based on the B1 diameter;

[0057] L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube section respectively, and ∑I W is the sum of the moments of inertia of the water surfaces of each part of the ballast water in the pipe segment about their respective axes.

[0058] The present invention has the following beneficial effects:

[0059] The present invention is directed to a special variable cross-section immersed tube segment structure, which can standardize the calculation of the metacentric height of a variable cross-section immersed tube tunnel. By determining the metacentric height of the tube segment, the stability of the tube segment under various working conditions can be controlled, ensuring the safety and stability of the variable cross-section immersed tube segment during floating transportation in water. The present invention solves the problem of the force on the variable cross-section immersed tube segment during floating and floating transportation, effectively reducing the design difficulty and the construction control risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 FIG. 6 is a schematic structural diagram of the first form of the variable cross-section of the variable cross-section immersed tube segment according to an embodiment of the present invention;

[0061] Figure 2 FIG. 10 is a schematic structural diagram of the second form of the variable cross-section of the variable cross-section immersed tube segment according to an embodiment of the present invention;

[0062] Figure 3 FIG. 14 is a schematic structural diagram of the third form of the variable cross-section of the variable cross-section immersed tube segment according to an embodiment of the present invention;

[0063] Figure 4 FIG. 18 is a schematic structural diagram of the fourth form of the variable cross-section of the variable cross-section immersed tube segment according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Here, the schematic embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

[0065] It should be noted that all directional indications (such as up, down, left, right, front, back, upper end, lower end, top, bottom...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0066] 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 body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meaning of the above terms in the present invention can be understood according to specific circumstances.

[0067] In addition, in the present invention, descriptions such as "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. Additionally, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions 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.

[0068] The following will Figures 1 to 4 further elaborate on the present invention in detail. Currently, there is no standard method for calculating the metacentric height of a variable cross-section immersed tube tunnel. For an immersed tube tunnel with a constant cross-section, the positions of the center of gravity and the center of buoyancy in the plane are the same. However, for a variable cross-section immersed tube segment, the inconsistent positions of the center of gravity and the center of buoyancy will cause an eccentric moment, leading to the overturning of the tube segment. Therefore, it is very necessary to confirm the metacentric height, this eccentric moment, and to regulate the positions of the center of gravity and the center of buoyancy.

[0069] Example 1: Please refer to Figures 1 to 4 , the present invention provides a technical solution, a method for determining the metacentric height of a variable cross-section immersed tube segment, which includes the following steps:

[0070] Step 1: Establish the plane forms of different variable cross-section immersed tube segments; the plane forms of different variable cross-section immersed tube segments are respectively the constant cross-section - variable cross-section form, the constant cross-section - variable cross-section - constant cross-section form, and the variable cross-section - constant cross-section form;

[0071] Step 2: Calculate the metacentric height of the variable cross-section immersed tube segment using theoretical formulas;

[0072] Step 3: The metacentric height is divided into two aspects: without ballast water during the floating transportation stage and with ballast water during the floating transportation stage.

[0073] Specifically, in the solution of this example, during the floating transportation stage: without ballast water:

[0074] Form 1: The calculation formula for the metacentric height in Step 2 is:

[0075]

[0076]

[0077] In the formula: H is the structural height of the tube segment (m); h is the freeboard value (m); B1 and B2 are the diameters at both 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; H f is the distance (m) between the center of buoyancy and the center of gravity of the tube segment, H wdlLet \(M\) be the metacentric height (m), and it is positive when the center of gravity of the pipe section is above the center of buoyancy. On the premise that the inclination of the pipe joint is less than \(10^{\circ}\), the freeboard height in the formula can be calculated by the following formula:

[0078]

[0079] In the formula: \(G\) k is the standard value of the self-weight of the pipe section (kN); \(G\) a is the standard value of the weight of the outfitting and temporary components of the pipe section (kN); \(H\) 1 is the adjustment thickness of the anti-anchoring layer (m); \(\gamma\) w is the unit weight of water (kN / m 3 ³), and \(S\) is the projected area of the variable cross-section pipe section;

[0080] Form 2:

[0081]

[0082] In the formula: \(H\) is the structural height of the pipe section (m); \(h\) is the freeboard value (m); \(B_1\) and \(B_2\) are the diameters at both ends of the variable cross-section immersed tube joint respectively; \(L_1\), \(L_2\), and \(L_3\) are the axial lengths of different cross-sections of the variable cross-section immersed tube joint respectively;

[0083] Form 3:

[0084]

[0085] In the formula: \(H\) is the structural height of the pipe section (m); \(h\) is the freeboard value (m); \(B_1\) and \(B_2\) are the diameters at both ends of the variable cross-section immersed tube joint respectively; \(L_1\) and \(L_2\) are the axial lengths of different cross-sections of the variable cross-section immersed tube joint respectively;

[0086] Form 4:

[0087]

[0088] In the formula: \(H\) is the structural height of the pipe section (m); \(h\) is the freeboard value (m); \(B_1\) is the diameter at one end of the variable cross-section immersed tube joint; \(B_2\) is the vertical height by which the other end of the variable cross-section immersed tube joint slopes downward based on the \(B_1\) diameter; \(B_3\) is the vertical height by which the other end of the variable cross-section immersed tube joint slopes upward based on the \(B_1\) diameter; \(L_1\) and \(L_2\) are the axial lengths of different cross-sections of the variable cross-section immersed tube joint respectively.

[0089] Specifically, in the solution of this embodiment, during the floating transportation stage: with ballast water:

[0090] Form 1: The calculation formula for the metacentric height in step 2 is:

[0091]

[0092] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both ends of the variable cross-section immersed tube section respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube section respectively, and H f is the distance between the center of buoyancy and the center of gravity of the pipe section (m), and H wdl is the metacentric height (m), and ∑I W is the sum of the moments of inertia of the water surfaces of each part of the ballast water in the pipe section about their respective axes. It is positive when the center of gravity of the pipe section is above the center of buoyancy. The freeboard height can be calculated by the following formula:

[0093]

[0094] Where: G k is the standard value of the self-weight of the pipe section (kN); G a is the standard value of the weight of the outfitting and temporary components of the pipe section (kN); H 1 is the adjustment thickness of the anti-anchor layer (m); γ w is the unit weight of water (kN / m 3 ³), and S is the projected area of the variable cross-section pipe section;

[0095] Form 2:

[0096]

[0097] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both ends of the variable cross-section immersed tube section respectively; L1, L2, and L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube section respectively, and ∑I W is the sum of the moments of inertia of the water surfaces of each part of the ballast water in the pipe section about their respective axes;

[0098] Form 3:

[0099]

[0100] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both ends of the variable cross-section immersed tube section respectively; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube section respectively, and ∑I W is the sum of the moments of inertia of the water surfaces of each part of the ballast water in the pipe section about their respective axes;

[0101] Form 4:

[0102]

[0103] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 is the diameter at one end of the variable cross-section immersed tube segment; B2 is the vertical height of the other end of the variable cross-section immersed tube segment inclined downward based on the diameter of B1; B3 is the vertical height of the other end of the variable cross-section immersed tube segment inclined upward based on the diameter of B1; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment; ∑I W is the sum of the moments of inertia of the water surfaces of the ballast water in each part of the pipe section about their respective axes.

[0104] Example 2: Please refer to Figures 1 to 3 , the present invention provides a technical solution: a method for determining the weight and buoyancy center position of a variable cross-section immersed tube segment and correcting deviation, including the following steps:

[0105] Step 1: Establish the plane forms of different variable cross-section immersed tube segments;

[0106] Step 2: Use theoretical formulas to calculate the center of gravity and buoyancy center positions of the variable cross-section immersed tube segments under different plane forms considering the two-side bulkheads;

[0107] Step 3: Use theoretical formulas to calculate the distance between the center of gravity and buoyancy center and the unbalanced moment of the variable cross-section immersed tube segment;

[0108] Step 4: According to the distance between the center of gravity and buoyancy center and the structural form of the variable cross-section immersed tube segment, determine the scheme for regulating the center of gravity position, and calculate the load arrangement method for regulating the center of gravity position required when calculating the moment required to make the center of gravity and buoyancy center positions consistent;

[0109] Referring to Figure 1 , specifically, in the solution of this embodiment, the positions of the center of gravity and buoyancy center of different cross-section forms in step 2 are as follows:

[0110] Form 1:

[0111] Buoyancy center calculation formula:

[0112] In the case of axisymmetry of the component

[0113] Center of gravity calculation formula:

[0114] In the case of axisymmetry of the component y G = 0,

[0115]

[0116] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both 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, L3 and L4 are the bottom-sealing widths at both ends of the variable-section immersed tube segment, G1 is the gravity of the bottom-sealing section at one end, G2 is the gravity of the hollow equal-section, G3 is the gravity of the hollow variable-section, G4 to G5 are the gravity of the bottom-sealing section at the other end, y G , z G , x G are the abscissa, ordinate, and height above the vertical bottom surface;

[0117] Form 2: As Figure 2 shown,

[0118] Center of buoyancy calculation formula:

[0119] In the case of axisymmetry of the component, y G = 0,

[0120]

[0121] Center of gravity calculation formula:

[0122] In the case of axisymmetry of the component, y G = 0,

[0123]

[0124] Where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1, B2 are the diameters at both ends of the variable-section immersed tube segment; L1, L2, L3 are the axial lengths of different sections of the variable-section immersed tube segment, L4, L5 are the bottom-sealing widths at both ends of the variable-section immersed tube segment, G1 is the gravity of the bottom-sealing section at one end, G2 is the gravity of the hollow equal-section, G3 is the gravity of the hollow variable-section, G4 is the gravity of the bottom-sealing section at the other end, y G , z G , x G are the abscissa, ordinate, and height above the vertical bottom surface;

[0125] Form 3: As Figure 3 shown,

[0126] Center of buoyancy calculation formula:

[0127] In the case of axisymmetry of the component, y G = 0,

[0128]

[0129] Center of gravity calculation formula:

[0130] In the case of axisymmetry of the component, yG = 0,

[0131]

[0132] where: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 and B2 are the diameters at both 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 sealing widths at both ends of the variable cross-section immersed tube segment respectively, G1 to G5 are the gravity of the bottom-sealed cross-section at one end, G2 is the gravity of the hollow equal cross-section, G3 is the gravity of the hollow equal cross-section, G4 is the gravity of the bottom-sealed cross-section at the other end, y G , z G , x G are the abscissa, ordinate and height above the vertical bottom surface.

[0133] Specifically, in the solution of this embodiment, the unbalanced moments of the distances between the center of gravity and the center of buoyancy in different cross-section forms in step 3 are Δx G and G 总 ΔxG.

[0134] Specifically, in the solution of this embodiment, the required balancing moment in step 4 is considered in the case of not adding extra volume to the variable cross-section immersed tube segment.

[0135] Specifically, in the solution of this embodiment, the deviation correction method is considered as the q distribution under the condition of uniformly increasing the weight or applying pressure inside, considering the uniformly distributed weight of the full length on the other side of the center of buoyancy is 2G 总 ΔxG / L 2 , L is the full length from the center of buoyancy to the other side sealing wall, and at this time the positions of the center of gravity and the center of buoyancy are the same; the deviation correction method is considered as F = G under the condition of concentrated load 总 ΔxG / distance between the concentrated load and the center of buoyancy position.

[0136] Compared with the existing technology, the present invention has the following beneficial effects:

[0137] The present invention aims at the special variable cross-section immersed tube segment structure, and can standardize the calculation of the positions of the center of gravity and the center of buoyancy and the metacentric height of the variable cross-section immersed tube tunnel. By determining the positions of the center of gravity and the center of buoyancy and reasonably determining the metacentric height of the immersed tube, by determining the metacentric height of the tube segment, the stability of the tube segment under various working conditions can be controlled, and the safety and stability of the variable cross-section immersed tube segment during floating transportation in water can be ensured. The present invention solves the problem of the force of the variable cross-section immersed tube segment during floating and floating transportation, effectively reduces the design difficulty, and reduces the construction control risk.

[0138] The above has introduced the technical solutions provided by the embodiments of the present invention in detail. Specific examples are used herein to elaborate on the principles and implementation manners of the embodiments of the present invention. The description of the above embodiments is only applicable to helping understand the principles of the embodiments of the present invention. At the same time, for those of ordinary skill in the art, according to the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A method for determining the fixed inclination height of a variable cross-section immersed tube segment, characterized in that: The following steps are involved: Step 1: Establish the plane forms of immersed tube segments with different variable cross-sections; the plane forms of immersed tube segments with different variable cross-sections include equal cross-section-variable cross-section form, equal cross-section-variable cross-section form, and variable cross-section-equal cross-section form; Step 2: Calculate the fixed inclination height of the variable cross-section immersed tube segment using a theoretical formula; Step 3: The fixed inclination height is divided into two aspects: the floating stage without ballast water and the floating stage with ballast water; Floating stage: without ballast water: Form 1: The calculation formula for the fixed tilt height in step 2 is: 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; L1 and L2 are the axial lengths of different cross-sections of the variable cross-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: 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 the pipe section outfitting and temporary components (kN); H1 is the thickness of the anti-anchor layer adjustment (m); γ w is the water density (kN / m 3 ), S is the projected area of ​​the variable cross-section pipe section; Form 2: 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, L2, L3 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment respectively; Form 3: 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-section immersed tube segment; L1 and L2 are the axial lengths of different sections of the variable-section immersed tube segment; Form 4: In the formula: H is the structural height of the pipe section (m); h is the freeboard value (m); B1 is the diameter of one end of the variable-section immersed tube segment; B2 is the vertical height of the other end of the variable-section immersed tube segment tilted downward based on the diameter of B1; B3 is the vertical height of the other end of the variable-section immersed tube segment tilted upward based on the diameter of B1; L1 and L2 are the axial lengths of different sections of the variable-section immersed tube segment respectively.

2. The method for determining the fixed inclination height of a variable cross-section immersed tube segment according to claim 1, characterized in that: Floating stage: with ballast water: Form 1: The calculation formula for the fixed tilt height in step 2 is: Where: H is the 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 and L2 are the axial lengths of different cross-sections of the variable cross-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), ∑I W It is the sum of the moments of inertia of the ballast water surface of each part of the pipe section around its own axis. The center of gravity of the pipe section is above the center of buoyancy. The freeboard height can be calculated by the following formula: 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 the pipe section outfitting and temporary components (kN); H1 is the thickness of the anti-anchor layer adjustment (m); γ w is the water density (kN / m 3 ), S is the projected area of ​​the variable cross-section pipe section; Form 2: In the figure: H is the 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; L1, L2, and L3 are the axial lengths of different sections of the variable-section immersed tube segment; ∑I W is the sum of the moments of inertia of the ballast water surface of each part of the pipe section around its own axis; Form three: 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; L1 and L2 are the axial lengths of different cross-sections of the variable cross-section immersed tube segment, ∑I W is the sum of the moments of inertia of the ballast water surface of each part of the pipe section around its own axis; Form 4: Where: H is the height of the pipe section structure (m); h is the freeboard value (m); B1 is the diameter of one end of the variable cross-section immersed tube segment; B2 is the vertical height of the other end of the variable cross-section immersed tube segment tilted downward based on the diameter of B1; B3 is the vertical height of the other end of the variable cross-section immersed tube segment tilted upward based on the diameter of B1; L1 and L2 are the axial lengths of different sections of the variable cross-section immersed tube segment, respectively, ∑I W It is the sum of the moments of inertia of the ballast water surface in each part of the pipe section around its own axis.

Images