Field forensic and numerical investigation of thermal stability of a permafrost-protecting granular embankment structure of asphalt-pavement expressways in cold regions

Abstract

The traditional crushed-rock embankment (CRE) has proven to be one of the most successful cooling embankment structures during the operation of Qinghai-Tibet Railway. However, it remains untested whether or not traditional CRE can maintain stability of permafrost foundation under expressways under strong heat absorption of asphalt-pavement and climate warming. For the study, field tests were performed to evaluate cooling performance of traditional CRE in wider-width expressways. Then, A heat transfer model of the CRE was established, and a novel inverted “M”-shaped crushed-rock embankment (MCRE) was proposed. Finally, large numbers of numerical simulations were further performed to comparatively evaluate thermal behavior and cooling performances for both traditional CRE and novel MCRE in wider-width expressway construction. The study shows that (1) the expressway accelerates degradation rate of permafrost foundation under traditional CRE; (2) traditional CRE shows obvious sunny-shady slope effect, which cannot guarantee thermal stability of expressway; (3) the novel MCRE for the expressway increases the entry of cooling energy and therefore accelerates heat dissipation from the permafrost foundation; and (4) the novel MCRE improves long-term thermal stability of the expressway. The research could provide important technical reference for the construction of wider-width expressways in permafrost areas in the future.

Keywords

• Crushed-rock material
• Expressway
• Asphalt-pavement
• Thermal stability
• Permafrost