PERFORMANCE OF EARTH DAMS DURING EARTHQUAKES

Particular emphasis is given to dam performance in six major earthquakes—San Francisco (1906); Ojika, Japan (1939); Fallon, Nevada (1954); Kern County, California (1952); Tokachi-Oki, Japan (1967); and San Fernando, California (1971). An attempt is made to determine relationships between embankment characteristics and observed performance. It is concluded that (1)Hydraulic fill dams on stable foundations can safely withstand accelerations up to about 0.2g from Magnitude 6.5 earthquakes; (2)virtually any well-built dam can withstand moderately strong shaking up to about 0.2g or more with no detrimental effects; (3)dams built of clay soils seem to be able to withstand extremely strong shaking from large magnitude earthquakes without significant damage; (4)dams may fail up to 24 hrs after being shaken by an earthquake probably due to cracking leading to piping and erosion; and (5)primary concern should be given to dams constructed of saturated sandy soils or on sand foundation materials. Prototype performance is cited as a basis for these conclusions.