Marginal Permafrost a Foundation Material in Transitionby Mark Musial, P.E., (M.ASCE),
Gregory E. Wyman, P.E., (M.ASCE),
At the edges of the world's cold regions lie areas of marginal permafrost. It is a changing landscape that seems to be growing in extent, yet it retains chameleon-like qualities that change with time and climate. These areas are defined by the ground's potential to change from frozen to thawed states during the life a project, with a resulting change in the ability to carry a load. Hence, they are a foundation material that is in transition. Marginal permafrost is found in many areas, including those that would otherwise be thermally stable except for project-related disturbance; areas of locally warmer conditions, such as south facing slopes; or areas affected by wider climate change, such as that seen in Alaska since 1890. Ground temperatures in areas of marginal permafrost are typically greater than -1 C (30F) and often isothermal for some depth. These areas are found in broad zones of discontinuous and sporadic permafrost (Figure 6.1) that are found at the margins of the arctic, as well as alpine regions farther south.
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