Study on the heat and deformation characteristics of an expressway embankment with shady and sunny slopes in warm and ice-rich permafrost regions

Abstract

Abstract In permafrost regions, the construction of embankment leads to the permafrost degradation, further affecting the embankment stability. Considering wider bituminous pavement and higher technical standard for expressway than ordinary highway, the heat and deformation behaviors of the separated expressway are investigated through a full-scale field experimental expressway embankment in the Qinghai-Tibet Plateau. The results show that: (1) the strong endothermic effect and heat accumulation effect of expressway embankment greatly reduce its thermal and deformation stability and intensify the shady-sunny slope effect. The decline rate of permafrost table, settlement rate and transverse deformation difference are 1.59, 1.33 and 1.94 times those of the Qinghai-Tibet Highway, respectively. (2) Under the comprehensive function of the heat gathering effect, the shady-sunny slope effect and strong convective heat transfer on windward slope, the maximum thawing depth under the sunny slope significantly increases with time, and that under the shady slope shoulder relatively slightly increases, while it under the shady slope toe remains basically unchanged. (3) The deformations at the sunny and shady slope shoulders are divided into slow settlement, rapid settlement and stabilization deformation/upheave. The slow settlement is mostly due to thaw settlement, and the rapid settlement is mainly originated from thaw settlement and thaw solidification of permafrost.