Long-term performance of the ventilation-enhanced embankment in permafrost regions

The long-term performance of embankment in permafrost regions is related to the temperature change of the underlying permafrost. A crucial issue to embankment is to prevent the degradation of the underlying permafrost due to temperature change, especially for expressways. The ventilation-enhanced embankment with perforated ventilation pipe and blocky stone is treated as a potential cooling approach to protecting the underlying permafrost. However, it still remains insufficient considerations in assessment for its long-term performance. To fully assess the effect of the ventilation-enhanced embankment, a thermal–fluid–mechanical coupling model was developed. The model involves air advection, water content change, and the mechanical behavior caused by temperature change. The model was solved numerically in the COMSOL Multiphysics, and the non-symmetry of temperature, stress, and settlement was analyzed. The results indicate that the ventilation-enhanced embankment exhibits a significant cooling effect under wider pavement although the cooling effect will be weakened along the pipe’s direction. A tensile stress zone appeared at both slope toes. Meanwhile, the maximum settlement of the ventilation-enhanced embankment was only 64.6% of the settlement of traditional embankment. The uneven settlement between shady and sunny slopes was observed, but it could still meet the embankment settlement requirement. The analysis shows that the numerical model is reliable in predicting the long-term performance of the ventilation-enhanced embankment. It can provide a basis to assess embankment deformation problems of expressways in permafrost regions.