Frost heave predictions of buried chilled gas pipelines with the effect of permafrost

Frost heave is an anticipated issue for the arctic pipeline design. In this study, the pipe displacement due to frost heave is assumed as the amount of soil heave at the free-field area, where the influence of the restraint of pipeline in frozen ground is negligible. To predict the pipe displacement, a quasi two-dimensional explicit finite difference model was developed and Segregation Potential (SP) concept was applied to the model. The developed frost heave model was verified by a full-scale buried chilled gas pipeline experiment in Fairbanks, Alaska. The simulated thermal analysis results agreed with the observed results. Simulation of the pipe displacement was conducted for two ground conditions — with and without permafrost. In the case with permafrost, rising of the permafrost table was simulated. The result indicated that pipe displacement stops when the freezing front reaches the permafrost table. However, heave continues for the ground free of permafrost. Segregation heave played a more significant role to the total heave in the case of no permafrost than that with permafrost. The total heave without permafrost was 30% more than that with permafrost in a 25-year simulation.