However, due to the structural characteristics, the single-layer insulation pipe has weak resistance to external pressure; in the shallow waters of the Bohai Sea, this problem is not prominent, but as the water depth increases, the single-layer insulation pipe has to withstand a large external Hydrostatic pressure. Therefore, crush buckling under hydrostatic pressure becomes a problem that must be considered in the design of single-layer insulated submarine pipelines. For the first time, the single-layer insulation pipe of an oil field in the South China Sea is subjected to crush buckling analysis.
1 Force analysis of submarine single-layer insulation pipe under hydrostatic pressure At present, the cross-sectional structure of CNOOC used as a single-layer insulation pipe for submarine pipelines is as shown.
1.1 Stress analysis model of each layer of single-layer insulation pipe under hydrostatic pressure The structure of the IM seabed single-layer insulation pipe and the characteristics of each layer of material are complex, and the force is also complicated. The hydrostatic pressure received by the outside of the pipe passes through the concrete counterweight layer. Polyethylene protective layer, polyurethane insulation: Jia Xu, male, senior engineer, graduated from Shanghai Jiaotong University in 1988 with a master's degree in marine engineering, and now works in the structural room of CNOOC Research Center. Address: Room 901, Haiyou Building, No. 6 Xiaozhi Street, Dongzhimen, Dongcheng District, Beijing (Postal Code: 100027) Tel: 010-Transformation.
1.2 Hydrostatic pressure is applied to the stress distribution of each layer in the concrete counterweight layer of single-layer insulation pipe. When the hydrostatic pressure p acts directly on the concrete counterweight layer, the stress on each layer of the single-layer insulation pipe is as shown.
1.3 Hydrostatic pressure is applied to the stress distribution of each layer in the polyethylene protective layer of the single-layer insulation pipe. When the hydrostatic pressure p acts directly on the polyethylene protective layer, the force of each layer of the single-layer insulation pipe is as shown.
Similarly, since the layers of the single-layer insulation pipe are continuous and coordinated, and the deformation is uniform, (1) the deformation inside the polyethylene protection layer is equal to the deformation on the outer side of the polyurethane insulation layer because the layers of the single-layer insulation pipe are continuous, Coordinated, the deformation is consistent, then (1) the deformation of the inner side of the concrete weight layer is equal to the deformation of the outer side of the polyethylene protective layer (2) the deformation of the inner side of the polyurethane insulation layer is equal to the deformation of the outer side of the steel tube (2) the inner side of the polyethylene protective layer The deformation is equal to the deformation of the outer side of the polyurethane insulation layer. The equations (5) and (6) are solved simultaneously, and the solved and p2 generations are returned (upper page 343). The above analysis results have been used for the design of the example project, and Passed the inspection of a third-party inspection agency.
4 Conclusion Based on the theory of elastic mechanics, according to the structural characteristics of single-layer insulation pipe, the interlayer transfer characteristics of the cross-section force and the deformation coordination conditions, the calculation method of crush buckling analysis of seabed single-layer insulation pipe under hydrostatic pressure is established. The method established in this paper can be used for the design of crushing buckling of submarine single-layer insulation pipes.
(Finish)
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