Effect of anti-seepage measures for maintaining thermal stability under flood dike in permafrost

When a flood protection dike is built in cold regions, the underlying permafrost may undergo a significant degradation, which will cause a substantial loss of the dike stability. In order to access the efficiencies of anti seepage measures in reducing the permafrost degradation, numerical simulations with different cases are performed over 20 years in this paper. The calculated results show that foundation permafrost below the dike will rapidly thaw to a depth more than 14 m within 20 years without any anti-seepage measures, which caused mainly by the thermal disturbance of construction and the water seepage derived from the river. The use of various anti-seepage measures gives a good promise against permafrost degradation. Of which, the measures with backfilling 0 degrees C soils and laying heat insulating layer and with building watertight screen show the favorable performance, while the measures with laying waterproof material and with backfilling low permeability soil just act on decelerating the permafrost degradation.