Calero Dam is a 30-m-high embankment dam located in a seismically active area, about 21 km southeast of San Jose, California. The dam straddles a flat and wide stream valley blanketed by 4.5 to 6 m of alluvium overlying bedrock. The alluvium was excavated beneath the embankment upstream shell but was left in place beneath the downstream shell. The lower 1.5 to 3 m of the alluvium consists of sandy gravel and gravelly sand, whereas the upper 1.5 to 3 m is mostly fine-grained soil of medium plasticity. The liquefaction resistance of the coarse-grained alluvium (CGA) was investigated with Standard Penetration Test borings, Becker Penetration Test soundings, and shear wave velocity, V_s, measurements. This paper describes the field investigations and analyses of liquefaction potential. The effects of the embankment on the penetration resistance of the CGA and its liquefaction resistance are discussed.
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