Thermal Regime Analysis and Protective Measure Evaluation for Wide Embankment in Permafrost Regions of Qinghai-Tibet Plateau

Abstract

This study analyzed the effects of a wide embankment on the thermal regime of permafrost and evaluated the feasibility of different measures to protect the permafrost underlying the wide embankment. Based on a specific embankment section of the Qinghai-Tibet highway and field observed data, a finite-element model was built and verified to conduct thermal analysis. Based on numerical analysis, the temperature fields and thawing depths of embankments with different widths were analyzed. The influences of different protective measures on the thermal stability of embankments were evaluated. The findings indicate that, after embankment construction, the annual ground temperature and maximum thawing depth increase with time. Thus, the embankment construction causes serious disturbance of the thermal stability of permafrost. An embankment with a larger width has a lower thermal stability. The results also show that raising the embankment height, setting a crushed stone layer, or setting an expanded polystyrene (EPS) layer can improve the thermal stability of an embankment. However, the improving effect of a single protective measure is not obvious for wide embankments with widths larger than 26 m. A combination of a crushed stone layer and an EPS layer provides the best protective effect on the thermal stability of a wide embankment. Thus, it is recommended as a protective measure for wide embankments of expressways in permafrost regions of the Qinghai-Tibet Plateau.