Abstract
The aim of this paper was to reveal the distribution law of permafrost thermal thawing sensibility and thaw depth caused by road construction in Qinghai-Tibet engineering corridor (QTEC). The prediction models of permafrost thermal thawing sensibility and thaw depth have been developed by incorporating the MODIS and in situ soil temperature observation data. The comprehensive earth-atmosphere-coupled numerical models of different embankment structures have been utilized to calculate the thaw depth of the underlying permafrost foundation. Finally, using the given data and above developed prediction models, the distribution maps of permafrost thermal thawing sensibility and thaw depth in QTEC are obtained by grid calculation. The results show the following: (1) Insensitive permafrost of QTEC mainly distributes in the large-scale mountain and high latitude area, and highly sensitive permafrost is located in the perennial river bed, flood plain, and terrace regions. (2) Road construction has a strong thermal disturbance to underlying permafrost, and the proportion of large thaw depth area of separate embankment is obviously smaller than that of 26 m full-width embankment. (3) Increase of subgrade interval reduces the proportion of large thaw depth areas, and the application of separate embankment structure is an effective engineering means for the Qinghai-Tibet expressway.
Highlights
With the construction of the Qinghai-Tibet Railway, a series of communication pipelines, oil and gas pipelines, and power grid transmission projects have plan to build in Qinghai-Tibet engineering corridor (QTEC) [1]
Air temperature, °C -4.5 -5.5 -3.5 -3.0 -4.5 -5.5 -3.0 -3.5 -4.5 -3.5 -3.0 -5.5 coupled numerical models of 26 m full-width and 13 m separate embankment are used to calculate the thaw depth of the underlying permafrost foundation since road construction
The Moderate-resolution Imaging Spectrometer (MODIS) Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) datasets (MOD11A2, MOD13Q1) were downloaded from the Land Processes Distributed Active Archive Center (LPDAAC) of NASA, and the digital elevation model (DEM) SRTM3 dataset was downloaded from the Consortium for Spatial Information (CSI) of CGIAR [27, 28]
Summary
With the construction of the Qinghai-Tibet Railway, a series of communication pipelines, oil and gas pipelines, and power grid transmission projects have plan to build in QTEC [1]. Permafrost is a special natural and ecological product of the Qinghai-Tibet Plateau, and its spatial distribution characteristics directly affect the safety and stability of engineering constructions [5,6,7]. Influenced by human activities or engineering structures, the frozen soil at the permafrost table will melt. The different ground temperature, surface characteristics, and ice-containing conditions will cause different thermal respond sensibility to external thermal disturbance and make the difference of thaw depth. The thermal thawing sensibility (Se) can be used as the indicator of frozen soil thermal responds speed [8], and it is one of the key influencing factors of permafrost characteristics. The research on the permafrost thermal thawing sensibility and thaw depth
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