Method for calculating ground breaking force and checking pipeline strength in buried submarine pipeline lifting process

Abstract

The invention discloses a ground breaking force calculation and pipeline strength checking method in the buried submarine pipeline lifting process. The ground breaking force calculation and pipeline strength checking method in the buried submarine pipeline lifting process comprises the following steps that S1, a first BCT35 calculation model is established, and flat pipeline lifting analysis is conducted; s2, processing and analyzing a calculation result of the first BCT35 calculation model; s3, establishing a second BCT35 calculation model and carrying out flat pipe hoisting analysis; s4, processing and analyzing a calculation result of the second BCT35 calculation model; s5, establishing a third BCT35 calculation model and carrying out flat pipe hoisting analysis; s6, processing and analyzing a calculation result of the third BCT35 calculation model; s7, the modeling calculation and result analysis steps are repeated, and iteration is carried out continuously; and S8, pipeline strength checking is carried out through DNV software. According to the method for calculating the ground breaking force and checking the pipeline strength in the pipe lifting process of the buried submarine pipeline, safety guarantee is provided for flat pipe lifting operation of projects such as pipeline hidden danger treatment and maintenance and first-aid repair.

Description

Technical Field

[0001] The invention belongs to the technical field of horizontal pipe lifting for submarine pipeline maintenance and emergency repair, and in particular relates to a method for calculating the earth-breaking force during the pipe lifting process of a deeply buried submarine pipeline and verifying the pipeline strength. Background Art

[0002] When performing horizontal pipe lifting operations on in-service submarine pipelines for emergency repair, it is often necessary to directly lift the pipelines with a certain buried depth out of the soil of the seabed. However, the existing BCT35 software and OFFPIPE software commonly used for horizontal pipe lifting analysis cannot automatically simulate the ground-breaking force that the pipeline is subjected to. In addition, the existing submarine pipeline design specification (DNV-RP-F110 "High-temperature and High-pressure Pipeline Structure Design") only gives the recommended formula for calculating the ground-breaking force per unit length of the pipeline at a certain buried depth. When there is a certain angle between the pipeline and the horizontal plane of the seabed during the lifting process, the effective lifting length of the pipeline in the soil, the calculation method of the ground-breaking force corresponding to the effective lifting length, and the pipeline strength verification method are not given.

[0003] Therefore, it is urgent to design a method for calculating the ground-breaking force and verifying the pipeline strength during the lifting process of a buried submarine pipeline, so as to solve the problem mentioned above that in the prior art, when performing horizontal pipe lifting analysis on an in-service submarine pipeline with a certain buried depth, the effective lifting length of the pipeline in the soil and the ground-breaking force and pipeline strength verification method corresponding to the effective lifting length cannot be directly calculated. Summary of the invention

[0004] In order to solve the technical problem mentioned in the prior art that when performing horizontal pipe lifting analysis on an in-service submarine pipeline with a certain buried depth, the effective lifting length of the pipeline in the soil and the ground-breaking force corresponding to the effective lifting length and the pipeline strength verification method cannot be directly calculated, a ground-breaking force calculation method and pipeline strength verification method for the lifting process of a deeply buried submarine pipeline are provided to solve the above problems.

[0005] To achieve the above-mentioned purpose, the specific technical scheme of the method for calculating the ground-breaking force and checking the pipeline strength during the lifting process of a buried deep submarine pipeline of the present invention is as follows: A method for calculating the ground breaking force during the lifting process of a buried deep seabed pipeline and verifying the pipeline strength comprises the following steps: S1. Establish the first BCT35 calculation model and perform horizontal pipe lifting analysis; S2, processing and analyzing the calculation results of the first BCT35 calculation model; S3, establish the second BCT35 calculation model and perform horizontal pipe lifting analysis; S4, processing and analyzing the calculation results of the second BCT35 calculation model; S5. Establish the third BCT35 calculation model and perform horizontal pipe lifting analysis; S6, processing and analyzing the calculation results of the third BCT35 calculation model; S7. Repeat the above modeling calculation and result analysis steps and continue to iterate; S8. Check pipeline strength using DNV software.

[0006] Furthermore, 10 nodes are set on the pipeline, namely node A, node B, node C, node D, node E, node F, node G, node H, node I and node J, and the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip are also set in the soil body. Node A is the central symmetry point of the entire pipeline, node B is the position of the side crane used for horizontal pipe lifting, node C is the midpoint of node B and node D, node D is the mud outlet point of the pipeline, node E, node F, node G, node H and node I are the intersection points of the central axes of the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip and the pipeline respectively, and node J is the initial point of the unlifted section of the pipeline.

[0007] Furthermore, the first BCT35 calculation model was established and a horizontal pipe lifting analysis was performed, including the ground-breaking force of 0.5 times the burial depth of the pipeline in the soil. The ground-breaking force was loaded into the BCT35 model in the form of equivalent density, and the position coordinates of each node of the pipeline at the lifting height of 2.3m at node B were calculated. The burial depth of each node under this working condition and the initial point E of the pipeline section that was not lifted were clarified.

[0008] Furthermore, the calculation results of the first BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D where the pipeline burial depth is 0 by interpolation method according to the calculation results of the BCT35 calculation model in S1, and obtaining the X-axis coordinates of node C, node E, node F, node G, node H, and node I according to the selection principles of the above nodes according to the X-axis coordinates of nodes A, node B, node D, and node J, and then calculating the burial depths of node E, node F, node G, node H, and node I by interpolation method, and calculating the ground-breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip, and the fifth soil strip.

[0009] Furthermore, a second BCT35 calculation model is established and a horizontal pipe lifting analysis is performed, including BCT35 modeling according to the coordinates of each node in S2, and the calculated breaking forces generated by the first soil bar, the second soil bar, the third soil bar, the fourth soil bar, and the fifth soil bar are loaded in the form of concentrated force onto nodes E, F, G, H, and I, respectively, and calculation and analysis are performed.

[0010] Furthermore, the calculation results of the second BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D where the pipeline is buried at a depth of 0 by interpolation according to the calculation results of the BCT35 calculation model in S3, obtaining the X-axis coordinates of node C, node E, node F, node G, node H and node I according to the selection principles of the above nodes based on the X-axis coordinates of node A, node B, node D and node J, and then calculating the burial depths of node E, node F, node G, node H and node I by interpolation, and calculating the ground-breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip.

[0011] Furthermore, the third BCT35 calculation model is established and the horizontal pipe lifting analysis is performed, including BCT35 modeling according to the coordinates of each node in S4, and the calculated breaking forces generated by the first soil bar, the second soil bar, the third soil bar, the fourth soil bar, and the fifth soil bar are loaded in the form of concentrated force on the node E, the node F, the node G, the node H and the node I, respectively, and the calculation and analysis are performed.

[0012] Furthermore, the calculation results of the third BCT35 calculation model are processed and analyzed, including using the interpolation method to calculate the X-axis coordinate of node D where the pipeline is buried at a depth of 0 according to the calculation results of the BCT35 calculation model in S5, and calculating the X-axis coordinates of nodes C, E, F, G, H and I according to the X-axis coordinates of nodes A, B, D and J in S4, and calculating the burial depths of nodes E, F, G, H and I by the interpolation method, and calculating the breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip.

[0013] Furthermore, the above modeling calculation and result analysis steps are repeated and iterated continuously until the buried depth of node D is exactly 0 in the calculation result of the Nth BCT35 model, or the X coordinate of node J calculated in this step is exactly the same as the X coordinate of node J calculated by the (N-1)th model, then the horizontal pipe lifting calculation of BCT35 is completed.

[0014] Furthermore, the pipeline strength check by DNV software includes extracting the maximum axial force and maximum bending moment of the pipeline from the calculation results of the Nth BCT35 model in S7, and then inputting them into the DNV software for pipeline strength check analysis.

[0015] The method for calculating the ground breaking force and checking the pipeline strength during the lifting process of a buried deep submarine pipeline of the present invention has the following advantages: The soil affected by the pipe lifting is divided into several strips vertically by using the strip division method for the soil above the effective lifting length range of the pipeline in the soil. According to the calculation formula of the breaking force recommended by the offshore pipeline design specification DNV-RP-F110, the breaking force generated by each strip is calculated respectively, and then each breaking force is loaded one by one in the form of concentrated force on the pipe section interacting with each strip. Then, the BCT35 software is used to model, load, calculate and analyze the horizontal pipe lifting. After several iterative simulation analyses, when the breaking force and other loads generated by each strip in the calculation results are completely consistent with the overall deformation of the pipeline in water and soil, that is, when the interaction between the pipe and the soil reaches a balanced interface during the pipe lifting process, the effective lifting length of the pipeline in the soil can be finally calculated. The maximum axial force and maximum bending moment of the pipeline at this time are extracted from the calculation results, and they are input into the DNV software together with other parameters to realize the strength verification of the pipeline under the horizontal pipe lifting condition, providing technical support and safety guarantee for the horizontal pipe lifting operations of projects such as hidden danger control of in-service pipelines and emergency repair of offshore pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the calculation of the earth-breaking force in the process of lifting the deep-buried submarine pipeline according to the present invention.

[0017] Description of the markings in the figure: 1. Soil; 2. Pipeline; 3. Seabed mud surface; 4. First soil strip; 5. Second soil strip; 6. Third soil strip; 7. Fourth soil strip; 8. Fifth soil strip; 9. Node A; 10. Node B; 11. Node C; 12. Node D; 13. Node E; 14. Node F; 15. Node G; 16. Node H; 17. Node I; 18. Node J. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0020] Please refer to the attached Figure 1The invention describes a method for calculating the ground breaking force during the lifting process of a buried deep seabed pipeline and verifying the pipeline strength.

[0021] When performing horizontal pipe lifting operations for maintenance and emergency repair of in-service submarine pipelines, it is often necessary to directly lift the pipeline 2 with a certain buried depth from the soil of the seabed. However, the existing BCT35 software and OFFPIPE software commonly used for horizontal pipe lifting analysis cannot automatically simulate the ground-breaking force borne by the pipeline 2, and the existing submarine pipeline design specifications ("High-temperature and High-pressure Pipeline Structure Design" DNV-RP-F110) only give the recommended formula for calculating the ground-breaking force per unit length of the pipeline 2 at a certain buried depth. When there is a certain angle between the pipeline 2 and the seabed horizontal plane during the lifting process, the effective lifting length of the pipeline 2 in the soil and the calculation method of the ground-breaking force corresponding to the effective lifting length are not given. Therefore, it is urgent to design a method for calculating the ground-breaking force and checking the strength of the pipeline during the lifting process of the buried deep submarine pipeline to solve the above-mentioned problems.

[0022] like Figure 1 As shown, the method for calculating the breaking force of a buried deep seabed pipeline during the pipe lifting process and checking the pipeline strength in the present invention comprises the following steps: S1. Establish the first BCT35 calculation model and perform horizontal pipe lifting analysis; S2, processing and analyzing the calculation results of the first BCT35 calculation model; S3, establish the second BCT35 calculation model and perform horizontal pipe lifting analysis; S4, processing and analyzing the calculation results of the second BCT35 calculation model; S5. Establish the third BCT35 calculation model and perform horizontal pipe lifting analysis; S6, processing and analyzing the calculation results of the third BCT35 calculation model; S7. Repeat the above modeling calculation and result analysis steps and continue to iterate; S8. Perform strength check of pipeline 2 using DNV software.

[0023] The soil 1 above the effective lifting length of the pipeline 2 in the soil is divided into several soil strips by using the strip division method. The soil strips affected by the lifting pipe are divided vertically into several soil strips. According to the calculation formula for the breaking force recommended by the offshore pipeline design specification DNV-RP-F110, the breaking force generated by each soil strip is calculated respectively, and then each breaking force is loaded one by one in the form of concentrated force on the pipe section interacting with each soil strip. Then, the BCT35 software is used to model, load, calculate and analyze the horizontal pipe lifting. After several iterative simulation analyses, when the breaking force generated by each soil strip appears in the calculation results, the calculation results show that the breaking force generated by each soil strip is the same as the breaking force generated by each soil strip. The generated ground-breaking force and other loads are completely consistent with the overall deformation of pipeline 2 in water and soil, that is, when the interaction between pipe and soil reaches a balanced interface during the pipe lifting process, the effective lifting length of pipeline 2 in the soil can be finally calculated, and the maximum axial force and maximum bending moment of pipeline 2 at this time can be extracted from the calculation results. They are input into the DNV software together with other parameters to realize the strength verification of pipeline 2 under the horizontal pipe lifting condition, providing technical support and safety guarantee for the horizontal pipe lifting operations of projects such as hidden danger control of in-service pipeline 2 and emergency repair of offshore pipelines.

[0024] The calculation basis in this embodiment is processed as follows: 1) Assume that the actual buried depth of pipeline 2 is 1.5m; 2) The calculation of the ground breaking force of buried pipeline 2 is based on the relevant calculation formula in the specification "High-temperature and high-pressure pipeline structure design" DNV-RP-F110; 3) Use BCT35 software to calculate the horizontal pipe lifting, and use BCT35 software to propose the maximum axial force and maximum bending moment of pipeline 2, and then use DNV software to perform strength analysis of pipeline 2; 4) Assume that during the process of breaking the ground for pipeline 2, the height of the seabed mud surface 3 above pipeline 2 does not change significantly, and no soil 1 adheres to the surface of pipeline 2 after it is unearthed; 5) According to the strip division method in soil mechanics, the soil 1 affected by the lifting pipe is vertically divided into 5 strips of equal width, namely the first strip 4, the second strip 5, the third strip 6, the fourth strip 7 and the fifth strip 8. The breaking force generated by each strip is approximately calculated and then loaded on the corresponding pipe section in the form of 5 concentrated forces, as shown in the following figure: Figure 1 As shown; 6) In the process of calculation using BCT35 software, a total of 10 nodes are set on pipeline 2: node A9, node B10, node C11, node D12, node E13, node F14, node G15, node H16, node I17 and node J18, node A9 is the central symmetric point of the entire pipeline 2, node B10 is the position of the side crane used for horizontal pipe lifting, node C11 is the midpoint of node B10 and node D12, node D12 is the mud outlet point of pipeline 2, node E13, node F14, node G15, node H16 and node I17 are the intersection points of the central axis of the first soil strip 4, the second soil strip 5, the third soil strip 6, the fourth soil strip 7 and the fifth soil strip 8 with pipeline 2 (i.e., 5 points of action of breaking soil force), and node J18 is the initial point of the unlifted section of pipeline 2; 7) Assume that the lifting height of the side crane to the pipeline 2 node B10 (relative to the seabed mud surface 3) is 0.8m when lifting the horizontal pipe; 8) Assuming that the direction along pipeline 2 is the X axis and the vertical direction is the Z axis, establish a rectangular coordinate system XOZ, such as Figure 1 shown.

[0025] Further, if Figure 1 As shown in the figure, the first BCT35 calculation model is established and the horizontal pipe lifting analysis is performed, including assuming that the entire pipeline 2 is subjected to an average ground-breaking force of 0.5 times the burial depth (i.e., 0.75 m), and the pipeline 2 is subjected to an average ground-breaking force of 0.5 times the burial depth in the soil 1. The ground-breaking force is loaded into the BCT35 model in the form of equivalent density, and the position coordinates of each node of the pipeline 2 at the node B10 with a lifting height of 2.3 m (0.8 m lifting height + 1.5 m burial depth) are calculated, and the burial depth of each node under this working condition and the initial point E of the unlifted section of the pipeline 2 are clarified.

[0026] Further, if Figure 1 As shown, the calculation results of the first BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D12 (i.e., mud outlet point) where the buried depth of pipeline 2 is 0 by interpolation method according to the calculation results of the BCT35 calculation model in S1, obtaining the X-axis coordinates of node C11, node E13, node F14, node G15, node H16, and node I17 according to the X-axis coordinates of nodes A9, node B10, node D12, and node J18, and according to the selection principles of the above nodes, and then calculating the buried depths of nodes E13, node F14, node G15, node H16, and node I17 by interpolation method respectively, and then calculating the breaking forces generated by the first soil strip 4, the second soil strip 5, the third soil strip 6, the fourth soil strip 7, and the fifth soil strip 8 by the calculation formula recommended in DNV-RP-F110.

[0027] Further, if Figure 1As shown, establishing the second BCT35 calculation model and performing horizontal pipe lifting analysis includes modeling BCT35 according to the coordinates of each node in S2, loading the ground-breaking forces generated by the first soil strip 4, the second soil strip 5, the third soil strip 6, the fourth soil strip 7, and the fifth soil strip 8 calculated in S2 in the form of concentrated force onto nodes E13, F14, G15, H16, and I17, respectively, and performing calculation and analysis.

[0028] Further, if Figure 1 As shown, the calculation results of the second BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D12 (i.e., mud outlet point) where the buried depth of pipeline 2 is 0 by interpolation method according to the calculation results of the BCT35 calculation model in S3, obtaining the X-axis coordinates of node C11, node E13, node F14, node G15, node H16, and node I17 according to the X-axis coordinates of nodes A9, node B10, node D12, and node J18, and according to the selection principles of the above nodes, and then calculating the buried depths of nodes E13, node F14, node G15, node H16, and node I17 by interpolation method, and then calculating the breaking forces generated by the first soil strip 4, the second soil strip 5, the third soil strip 6, the fourth soil strip 7, and the fifth soil strip 8 by the calculation formula recommended in DNV-RP-F110.

[0029] Further, if Figure 1 As shown, establishing the third BCT35 calculation model and performing horizontal pipe lifting analysis includes, on the basis of the second BCT35 calculation model, performing BCT35 modeling according to the coordinates of each node in S4, loading the calculated earth-breaking forces generated by the first soil strip 4, the second soil strip 5, the third soil strip 6, the fourth soil strip 7, and the fifth soil strip 8 in the form of concentrated force onto nodes E13, F14, G15, H16, and I17, respectively, and performing calculation and analysis.

[0030] Further, if Figure 1 As shown, the calculation results of the third BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D12 (i.e., mud outlet point) where the buried depth of pipeline 2 is 0 by interpolation method according to the calculation results of the BCT35 calculation model in S5, obtaining the X-axis coordinates of nodes C11, E13, F14, G15, H16, and I17 according to the X-axis coordinates of nodes A9, B10, D12, and J18 in S4, calculating the buried depths of nodes E13, F14, G15, H16, and I17 by interpolation method, and then calculating the breaking forces generated by the first soil strip 4, the second soil strip 5, the third soil strip 6, the fourth soil strip 7, and the fifth soil strip 8 by the calculation formula recommended in DNV-RP-F110.

[0031] Further, if Figure 1As shown, the above modeling calculation and result analysis steps are repeated and iterated continuously until the buried depth of node D12 is exactly 0 in the calculation result of the Nth BCT35 model, or the X coordinate of node J18 calculated in this step is exactly the same as the X coordinate of node J18 calculated by the (N-1)th model, then the horizontal pipe lifting calculation of BCT35 is completed.

[0032] Further, if Figure 1 As shown, the strength check of pipeline 2 by DNV software includes extracting the maximum axial force and maximum bending moment of pipeline 2 from the calculation results of the Nth BCT35 model in S7, and then inputting them together with other parameters into the DNV software to check and analyze whether the strength of pipeline 2 meets the requirements of the specification.

[0033] This embodiment provides a method for calculating the ground-breaking force during the lifting process of a deep-buried submarine pipeline and verifying the pipeline strength, which solves the problem that the existing calculation software BCT35 cannot automatically simulate and analyze the horizontal pipe lifting analysis of the in-service deep-buried pipeline 2 with ground-breaking force, and provides technical support and safety guarantee for the horizontal pipe lifting construction operations of projects such as hidden danger control of the in-service pipeline 2 and maintenance and emergency repair of submarine pipelines.

[0034] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for calculating the ground breaking force during the lifting process of a deep-buried submarine pipeline and verifying the pipeline strength, characterized in that: The following steps are involved: S1. Establish the first BCT35 calculation model and perform horizontal pipe lifting analysis; S2, processing and analyzing the calculation results of the first BCT35 calculation model; S3, establish the second BCT35 calculation model and perform horizontal pipe lifting analysis; S4, processing and analyzing the calculation results of the second BCT35 calculation model; S5. Establish the third BCT35 calculation model and perform horizontal pipe lifting analysis; S6, processing and analyzing the calculation results of the third BCT35 calculation model; S7. Repeat the above modeling calculation and result analysis steps and continue to iterate; S8. Check pipeline strength using DNV software.

2. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 1, characterized in that: There are 10 nodes set on the pipeline, namely node A, node B, node C, node D, node E, node F, node G, node H, node I and node J. The first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip are also set in the soil body. Node A is the central symmetry point of the overall pipeline, node B is the position of the side crane used for horizontal pipe lifting, node C is the midpoint of node B and node D, node D is the mud outlet point of the pipeline, node E, node F, node G, node H and node I are the intersection points of the central axes of the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip and the pipeline respectively, and node J is the initial point of the unlifted section of the pipeline.

3. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 2, characterized in that: The first BCT35 calculation model was established and a horizontal pipe lifting analysis was performed, including the pipeline being subjected to an average ground-breaking force of 0.5 times the burial depth in the soil. The ground-breaking force was loaded into the BCT35 model in the form of equivalent density, and the position coordinates of each node of the pipeline at the lifting height of 2.3m at node B were calculated. The burial depth of each node under this working condition and the initial point E of the pipeline section that was not lifted were clarified.

4. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 3, characterized in that: The calculation results of the first BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D where the pipeline is buried at a depth of 0 by interpolation according to the calculation results of the BCT35 calculation model in S1, obtaining the X-axis coordinates of node C, node E, node F, node G, node H, and node I according to the selection principles of the above nodes based on the X-axis coordinates of nodes A, node B, node D, and node J, and then calculating the burial depths of nodes E, node F, node G, node H, and node I by interpolation, and calculating the ground-breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip, and the fifth soil strip.

5. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 2, characterized in that: Establishing the second BCT35 calculation model and performing horizontal pipe lifting analysis includes performing BCT35 modeling according to the coordinates of each node in S2, loading the calculated breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip, and the fifth soil strip in the form of concentrated force onto nodes E, F, G, H, and I, respectively, and performing calculation and analysis.

6. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 5, characterized in that: The processing and analysis of the calculation results of the second BCT35 calculation model includes obtaining the X-axis coordinate of node D where the pipeline is buried at a depth of 0 by interpolation according to the calculation results of the BCT35 calculation model in S3, obtaining the X-axis coordinates of node C, node E, node F, node G, node H and node I according to the X-axis coordinates of node A, node B, node D and node J and the selection principle of the above nodes, and then calculating the burial depths of node E, node F, node G, node H and node I by interpolation, and calculating the ground-breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip.

7. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 2, characterized in that: Establishing the third BCT35 calculation model and performing horizontal pipe lifting analysis includes performing BCT35 modeling according to the coordinates of each node in S4, loading the calculated breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip, and the fifth soil strip in the form of concentrated force onto nodes E, F, G, H, and I, respectively, and performing calculation and analysis.

8. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 7, characterized in that: The calculation results of the third BCT35 calculation model are processed and analyzed, including obtaining the X-axis coordinate of node D where the pipeline is buried at a depth of 0 by interpolation according to the calculation results of the BCT35 calculation model in S5, obtaining the X-axis coordinates of nodes C, E, F, G, H and I according to the X-axis coordinates of nodes A, B, D and J in S4, calculating the burial depths of nodes E, F, G, H and I by interpolation, and calculating the breaking forces generated by the first soil strip, the second soil strip, the third soil strip, the fourth soil strip and the fifth soil strip.

9. The method for calculating the ground breaking force during the lifting process of a buried deep submarine pipeline and verifying the pipeline strength according to claim 2, characterized in that: Repeat the above modeling calculation and result analysis steps and iterate continuously until the buried depth of node D is exactly 0 in the calculation result of the Nth BCT35 model, or the X coordinate of node J calculated in this step is exactly the same as the X coordinate of node J calculated by the (N-1)th model, then the horizontal pipe lifting calculation of BCT35 is completed.

10. The method for calculating the ground breaking force during the lifting process of a buried deep seabed pipeline and verifying the pipeline strength according to claim 1, characterized in that: The pipeline strength check by DNV software includes extracting the maximum axial force and maximum bending moment of the pipeline from the calculation results of the Nth BCT35 model in S7, and then inputting them into the DNV software for pipeline strength check analysis.

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