PIPE UPLIFT RESISTANCE IN FROZEN SOIL AND COMPARISON WITH MEASUREMENTS

The analysis and design of buried chilled pipelines in frost heaving soils warrants a study of the complex pipe-soil interaction. Stress gradients are generated at the interface between frozen and unfrozen ground because of differential heave, produced as the chilled pipe crosses from the unfrozen, heave-susceptible terrain to the frozen, nonheaving one, resulting in the generation of uplift forces acting on the pipe portion buried in the frozen ground. The present paper characterizes the load-resistance response of the uplift-resistant side of the pipe section as it is pulled upward at a constant displacement rate through the frozen ground. Crack patterns in the frozen soil around the pipe section were observed in uplift tests. In view of this, a theoretical assessment of tension-fractured and compression-crushed zones, developed in the vicinity of the pipe, producing a reduced peak uplift resistance is discussed.