RTS could be initiated in these areas as the trend towards warmer summers results in the thaw of high ice content material buried at greater depths.
However, isolated masses of relic permafrost exist at temperatures close to 0 °C protected from rapid thawing by a thick layer of peat and soils with high ice content.
It finds that there are between 1,330 and 1,580 gigatons of carbon in the top three meters of global permafrost soil, in what are called yedomas (permafrost with particularly high ice content), and in Arctic river deltas.
Results show that the route plan determined by the method of selecting the road in permafrost region can avoid the high temperature and high ice content area, conform the terrain changes and evade the heat disturbance among the existing projects.
Based on these physical parameters, the six studied landforms can be classified into raised, dry landforms with minor ground ice content and a thin, discontinuous snow cover and into wet landforms with high ice content located in the topographical depressions in-between with medium to thick snow cover.
However, as half part of the roadbed was constructed over the permafrost characterized by high ground temperature and high ice content, slight changes of the permafrost might lead to roadbed problems, of which the settlement in embankment bridge transition section is an obvious and special one.
Yedoma, a suite of syngenetically frozen silty ice- and organic-rich deposits with large ice wedges that accumulated during the late Pleistocene, is vulnerable to thermal degradation and erosion because of the extremely high ice contents.
In addition, the creep of the underlying warm and high ice-content permafrost was inferred as the main cause for the foundation settlement.
These remnants are characterized by a higher elevation, a thick organic layer with very high ground ice content in the upper permafrost and a plant community somewhat atypical of the region.
The regions associated with the highest hazard are in the thaw-unstable zone characterized by relatively high ground-ice content and thick deposits of frost-susceptible sediments, as well as increased potential for permafrost thaw (Supplementary Figs. 1, 4).
X-ray CT scanning is a nondestructive method that provides the three-dimensional density (g cm−3) distribution of the scanned samples in order to differentiate ice content from higher density materials such as organics or clays52.
