Dynamic behaviour and seismic response of El Infiernillo dam

Abstract

AbstractEl Infiernillo, a 145 m high rockfill dam in Mexico built in a narrow V‐shaped canyon, was subjected to eight major earthquakes since its construction. In this study, the dynamic dam response is analysed using (i) the recorded November 15, 1975 bedrock‐crest acceleration histories and (ii) the results of a 1970 full‐scale test conducted by UNAM, in which eight upstream–downstream and longitudinal resonant frequencies and configurations were observed and documented. These observed and seismically induced dynamic responses are compared herein to predictions of two different numerical models of El Infiernillo dam; a newly developed simplified three‐dimensional (3D) model, and a 3D finite element model. The dynamic dam response characteristics are assessed, and performance of the employed numerical models is evaluated. It is found that (i) higher modes of vibration had participated significantly in the recorded seismic response and (ii) upstream–downstream response is well represented by the two numerical models employed. Using the simplified model, the September 19, 1985 earthquake non‐linear response is computed and shown to compare satisfactorily with its recorded counterpart in the upstream‐downstream and vertical directions. The largest computed dynamic accelerations, stresses and strains are found to occur within the upper third of the dam body.