Thermal effects analysis of separated crushed-rock embankment configurations on underlying permafrost

The thermal stability of embankments in permafrost regions is significantly influenced by rising temperatures resulting from climate change and engineering activities. This study examines the thermal interactions and cooling performance of various separated embankment types—including ordinary embankments (SOE), crushed rock-based embankments (SCE), and two hybrid configurations (SC_FE and SC_RE)—through a combination of field monitoring data and numerical simulations conducted along the Gonghe–Yushu high-grade highway (GYHH). A comprehensive numerical model encompassing air, porous media, and soil domains was developed to simulate convective and conductive heat transfer processes under complex permafrost conditions. Results show that the SCE effectively raises the permafrost table and reduces the maximum thawing depth due to enhanced ventilation and heat dissipation. Hybrid embankments exhibit asymmetric thermal behavior influenced by the placement of the crushed-rock structure; notably, the SC_FE configuration (crushed-rock in the front) demonstrates superior cooling performance compared to SC_RE. These findings offer theoretical support for optimizing embankment design to enhance the long-term stability of road infrastructure in permafrost regions.