The Frost Heave Calculation of Permafrost Pipeline

Abstract

Frost heave is the primary factor for potential destruction of the permafrost pipeline. Considering the Fenghuoshan area of the Ge-La Pipeline, the paper develops the finite element model for frost heave, and determines the amount of frost heave, frost stress around the pipe and Von Mises equivalent stress of the pipe wall, based upon the coupled thermo-mechanical method. The results indicate that the direction of frost heave is essentially vertical; the maximum frost stress occurs in the soil adjacent to the central section of the pipe, and the maximum Von Mises equivalent stress occurs at the top of the pipe. Based on a sensitivity analysis, the frost stress and Von Mises equivalent stress diminish with an increase of trench width and buried depth. The relationship between the frost stress and Von Mises equivalent stress and the pipe diameter and trench obliquity is rather complex. The frost stress value reaches a peak when the diameter is 150mm, and the Von Mises equivalent stress value reaches a peak when the trench obliquity is 10 degrees. The above results and methods have important significance for the design and construction of a permafrost pipeline.