Failure analysis of fractured dams during earthquakes by DEM

A comprehensive study on the dynamic behaviour of the fractured Koyna dam during earthquakes is performed using the distinct element method (DEM). The extensional functions of earthquake input and hydrodynamic simulation have been incorporated into the current program. The method of choosing the damping by the properties of each part of the system, mesh dependency and ground motion amplification are discussed in detail. Results show that the safety of the dam is ensured if the crack shape is horizontal or upstream-sloped; however, it is very dangerous if the crack slopes downstream. The whole failure processes of the two possible failure modes of the cracked dam, i.e. overturning or sliding of the top separated block during earthquakes under abnormal conditions, are also simulated. Some important phenomena such as the bounce of the top block and the relationship of the sliding and overturning are examined in detail.