ABSTRACT

Earthquakes impose additional loads on to embankment dams over those experienced under static conditions. The earthquake loading is of short duration, cyclic and involves motion in the horizontal and vertical directions. Earthquakes can affect embankment dams by causing any of the following:

– Settlement and cracking of the embankment, particularly near the crest of the dam; – Instability of the upstream and downstream slopes of the dam; – Reduction of freeboard due to settlement or instability which may, in the worst case,

result in overtopping of the dam; – Differential movement between the embankment, abutments and spillway structures

leading to cracks; – Internal erosion and piping which may develop in cracks; – Liquefaction or loss of shear strength due to increase in pore pressures induced by the

earthquake in the embankment and its foundations; – Differential movements on faults passing through the dam foundation; – Overtopping of the dam in the event of large tectonic movement in the reservoir basin, by

seiches induced upstream; – Overtopping of the dam by waves due to earthquake induced landslides into the reser-

voir from the valley sides; – Damage to outlet works passing through the embankment leading to leakage and

potential piping erosion of the embankment.