Study on the cooling effect of crushed rock-based embankment of high-grade highway in permafrost region under the influence of crushed-rock fragmentation and weathering

Abstract

In road construction within permafrost regions, the crushed rock-based embankments(CRBEs) are commonly used as active cooling measures, particularly on the Qinghai-Tibet Plateau. The unique climatic conditions in this region can lead to fragmentation and weathering of the crushed-rock within these embankments, subsequently diminishing their cooling effectiveness. This study, drawing on field observations from the Gonghe-Yushu high-grade highway(GYHH) and supplemented by numerical simulations, investigates how such degradation affects the embankment's cooling performance. Results indicate that fragmentation and weathering increase soil temperatures underneath the CRBE, accelerate the degradation rate of the permafrost table, and significantly reduce the radius and area of the frozen zone. Additionally, the permafrost table descends more slowly on shady slopes compared to sunny ones. Consequently, the altered pore structure and reduced ventilation due to rock degradation impede internal heat dissipation within the CRBE, thus undermining its cooling capacity.