The strength and stability of offshore pipelines in the presence of subaqueous permfrost on land landfall

Estimation of resistance of offshore pipelines on land landfall of shallow-water zone of the Arctic shelf, especially when their add subaqueous permfrost surrounding require to detect invalid pipe stress. Analytic expressions are obtained for determining the stresses in the wall of the offshore pipeline at the stage of pre-project development allow us to estimate the reserves of his strength during subaqueous permfrost surrounding defrostingin the area of landfall with minimal time cost, since the numerical simulation of contact interaction between the pipe - the soil in the software package, for example, ANSYS is associated with certain difficulties for defining and setting input parameters, the determination of the initial conditions, the choiceof an appropriate model of the soil, reliably describing the behavior of material under loading and the direct simulation of the Hertzian problem.
Materials and methods
On the basis of the numerical solution of differential equation of local bend of pipe wall containing geometrical characteristics of pipes, mechanical properties of their metal and value of pipeline pressure, have been received analytical expressions for determination of tension in wall of the offshore pipeline.
Results
Calculated values for definition of change of high-rise position of the pipeline, full longitudinal and equivalent stresses in pipeline wall are given when subaqueous permfrost defrosting on land landfall of shallow-water zone of the Arctic shelf.
Сonclusions
1. On the basis of the received analytical expressions for offshore pipelines it is carried out research intense the deformed condition of the offshore pipeline.
2. The received analytical expressions can be recommended for determination of stresses in wall of the offshore pipeline for stages of preproject development.