Chen, M.-T., and Harichandran, R. S. (1995). "Effect of spatially
varying ground motion on earth dam response." Proceedings, 10th ASCE
Engineering Mechanics Conference, Boulder, Colorado, 78-81.
Abstract
Over the last two decades, the seismic response of earth dams have been
analyzed primarily using shear beam and finite element models (Gazetas
1987). However, in previous studies, the seismic ground motions acting
at the base of a dam have been assumed to be identical at all location,
or at best a simple propagating wave. Recent research has shown that
significant variation of earthquake ground motion exists over the base
dimensions of large structures (Harichandran and Vanmarcke 1986, and
many others). The variation of seismic excitations characterized by wave
propagation as well as by coherency loss has a very significant impact
on the dynamic response of earth dams. This paper provides preliminary
results on the stochastic response of the Santa Felicia earth dam to
spatially varying earthquake ground motion (SVEGM). The results indicate
that SVEGM reduces the displacement response slightly, but can
significantly increase the maximum shear stress at the base.
The Santa Felicia earth dam is located on Piru Creek, 65 km northwest of
Los Angeles, and was selected since it has been studied extensively
(Abdel-Ghaffar and Scott 1979, Prevost et al. 1985). The dam is a modern
rolled-fill embankment with a central impervious core and pervious shell
upstream and downstream. The core and shell materials are basically
alluvial, consisting of clay, sand, gravel and boulders. The dam, shown
in Fig.1, is 83.8 m (275 ft) high above its rock foundation, 388.6 m
(1,275 ft) long at the crest. It is 137.2 m (450 ft) long across the
valley at the base.