On March 3, 1985, a strong earthquake shook central Chile causing about 150 deaths, about 2,000 injuries, and extensive property damage. Strong motion records were obtained at about 25 stations, one station recording a peak horizontal acceleration of about 0.7 g and several stations recording values over 0.2 g. Two tailings dams developed massive liquefaction failures while other tailings dams in close proximity did not fail. Thus these dams provide a unique opportunity to study the factors that determine the potential for liquefaction failures. Within the U.S., there are a larger number of tailings dams in areas where there is significant seismic activity. Because hazardous chemicals are used in the extraction of minerals from the ores, accidental release of these tailings can produce a significant environmental hazard, as well as a hazard to human lives in the downstream areas. This research program is highly relevant to reducing these safety and environmental hazards. The program consists of field and laboratory work to determine the properties of the tailings which are relevant to their liquefaction potential using state-of-the-art techniques. The properties to be determined include the steady state strength of the tailings and the generation of strains due to cyclic loading. The investigation will provide means for judging the appropriateness of state-of-the-art liquefaction evaluation techniques and will indicate any modifications that may be needed in these techniques.
