Modelling natural convection in a rockfill dam in Sweden

Rockfill embankment dams can exhibit natural convection in the downstream toe. Natural convection is caused by the temperature dependency of the air density. During winter, cold air at the dam surface sinks into the dam toe, and its warmer air ascends. The convection leads to decreased dam temperatures in the long term. In subarctic climates, the temperature reduction can induce permafrost, even if the annual mean air temperature is above water’s freezing point. Freezing of the dam’s downstream filters can lead to locally increased pressure, deteriorating the dam’s stability. Repeated freezing and thawing increase the risk of internal erosion. This paper uses numerical simulations to investigate the natural convection in a Swedish rockfill dam to provide for characterization of its potential negative influences