A composite backfill is a kind of light backfill formed by mixing waste foundry sand

flyash

expanded polystyrene（EPS） beads

cement and water in designated proportions.Inclusion of EPS beads can reduce or eliminate frost heave and thaw settlement

and thus can be used as backfill of road base in seasonal frost areas.A one-dimensional frost heave model was established based on the current moisture-heat coupling model.The model is able to take account of the elastoplastic behavior of EPS bead and its effect on frost heave taken place within the mass of composite backfill.The results given by the model are in a good agreement with the test results achieved from a previous companion study

which validates the use of this model in the prediction of frost heave of engineering works in seasonal frost areas.