Buckling analysis of piles in solid frozen soils

The object of the research is the behavior of axial compressed piles in the foundations on continuous permafrost soils under global warming. There is a degradation of permafrost soils at present. The permafrost layer is vertically divided into two parts: 1) the top, the active layer; 2) the bottom, the frozen mass. The active layer of soil thaws in summer and freezes in winter. Frozen soil behaves as a rock in winter and as a liquid mass on some soil thickness in summer. Accordingly, the surface forces acting on the pile surface in winter time disappear in the entire melted liquid soil layer in summer time. We considered the design of a pile by the condition of the first kind buckling (form) under axial compression. We took into account the conditions when the depth of the base thawing soil increases in the upper part of the pile at the stages of operation (in the summertime of the pile operation). In addition, we considered the calculation of the pile length under the same conditions at a given load on the pile at the stage of its design. To forecast the piles operating time in pile foundations or individual piles during global warming on the Earth, an algorithm for calculating pile length at the design stage is proposed. The paper provides a numerical example of calculating the pile operational life in the solid frozen soil of the foundation in an oil pipeline support.