Calculation Of Thermal-Stress On Shallow-buried Oil Pipeline In Cold Area

Against the particularity of the geographical environment where the cold-area pipeline is laid, the author first introduced the connotation and the classification of permafrost, and the physical properties which distinguish the permafrost from the ordinary soil. These physical properties include phase change, substance transfer properties and moisture migration characteristics. The author emphasizes on introducing the frost heaving mechanism of the permafrost, which includes the effect of moisture, temperature, freezing conditions, and external load factors; as well as how to prevent the frost heaving problem in the cold area project.This paper selects the physical parameters involved in the pipeline project, stimulates the conditions of ground and both sides of the border, constructs a finite element analysis model; On the basis of finite element software, it analysis the distribution of earth temperature and the condition of soil freezing beneath the ground, under the condition of the surface temperature's seasonal change. Thus make sure the maximum depth of freezing and freeze line distribution changes over time. Finally, it analysis the thermal stress, make sure how the pipeline wall's stress change during the soil frost heaving seasonal melting process and the vertical displacement of pipeline. On the set of mathematical methods and the spectral element method's basic theory, focused on Chebyshev interpolation theory, a spectral method and spectral element method for solving equations of heat conduction, the spectral method is applied to the question of the Coupled Thermodynamic Frozen Heave of frozen soil.