Potrerillos dam is a 120m high CFRD dam recently built in Mendoza, Argentina. The dam was built on top of a riverbed containing loose sand seams. Concern about the seismic stability of the dam derived in the construction of a large downstream buttress, not considered in the original design and bid. The key question that arose during the consequent claim is: was the buttress essential for the dam’s stability? In the paper, a twofold analysis of the problem is performed: i) the analytical methods employed in the original discussion are briefly introduced and discussed; ii) a simple static pushover analysis is performed numerically, where the sand seams are forced to follow the full strain path through contractive to dilating to critical state. In both analyses, the thrust required to displace the dam body is compared to the hydrostatic pressure to assess on dam’s stability. The results obtained using both methods are compared. The main conclusion is that the self-weight of the dam produces an increase in the undrained shear strength of the sandy seams that yields the downstream buttress not essential.
