Experimental investigation on the enhanced cooling performance of a new crushed-rock revetment embankment in warm permafrost regions

It has been proved that the crushed-rock revetment (CRR), used as technique for improving foundation stability in the Qinghai-Tibet Railway (QTR), produces an insufficient cooling effect on warm permafrost; this may affect the stability of the roadbed and pose a threat to its long-term safe operation, particularly in a warming climate. To solve this problem, a new embankment structure that combines the CRR and a slope thermal protection measure was designed, and a field experiment was carried out in a section of the QTR at Tuotuohe to examine its convection and thermal characteristics and to assess its cooling performance. The experimental results indicate that, compared with the traditional CRR, the new structure has a significantly increased cooling effect on the embankment slope. This is due to an effective prevention of side-slope warming in hot seasons and an enhanced forced convection cooling effect in cold seasons. In addition, this structure prevents sand-filling, which is beneficial in protecting the long-term cooling effect of the CRR on side slopes. This study provides valuable guidelines for the design and maintenance of roadbeds in warm permafrost regions.