Abstract
Highly idealized rockfill dam models are used for close examination of their failure mechanism under earthquake excitation. They have a symmetrically triangular configuration with regular arrangement of brass cylinders. The models are forced to failure by means of vibration, inclination or impulse applied at their base. The key step for their failure process is found to be an opening which develops at the deepest portion of the models. The opening can be attributed to a kind of buckling of the particles in a linear contact each other. As progress of the buckling requires a finite time duration, the earthquake failure is sometimes interrupted by the reversed direction of innertia force, suggesting great significance of acceleration period in such a failure.
