Abstract: Building a patchy permafrost physical model, which is composed of multiple formations, the paper researches the effect of thermo-hydro-mechanical(T-H-M) coupling around the buried oil pipelines in Tahe on the base of considering the effect of environmental temperature and flow medium temperature in the pipelines, and analyses the stress of the buried pipelines and takes a strength calculation on the pipelines. The distribution of stress and sedigraph are acquired by the multiphysical fields coupling COMSOL Multiphysics software, which is used to simulate two kinds of working condition of T-H-M coupling and uncoupling. The numerical simulation results indicate that temperature, water phase transition and water migration influence the stress field greatly. What’s more, the coupling among the moisture field, the temperature field and the stress field is very remarkable. Because of temperature change, patchy permafrost takes on freezing or thawing, which results in stress concentration and settlement around the pipelines, so as to harm the safety of buried pipelines.

Key words: patchy permafrost, oil pipeline, numerical simulation, porous medium, multifield coupling