Ground Motion Amplification from Vertical Propagation of Earthquake Waves

The paper is directed to follow a procedure where seismic responses are identified and recommendations to proceed with their applications are made quickly and economically, before engaging in a complex analysis. It is not intended for selecting design soil parameters or earthquake parameters for the final design of any specific dam. A selected earthquake accelerogram will produce response accelerations and strains that will cover a significant variety of accelerograms in terms of severity of earthquake damage to an earth dam. Scaling-up and scaling-down the selected outcrop motion broadens the spectrum of seismic response analyses using simple and effective SHAKE program for making decision on the need for further more sophisticated analyses, particularly when the 1-D response analysis shows potential problems. It is inappropriate to base the judgment of final seismic response of dam on 1-D analysis,. The traditional dynamic modulus reduction curves have been shown to be appropriate up to one percent strain. The analysis performed in this paper shows the maximum strain to be smaller than 0.5%. The Mexico City (MC) clay is used to demonstrate different soil types do exist in nature and, in some situation, can show quite different responses in different intensity seismic events. First, hypothetical soil deposits are used in evaluating factors affecting PHA variation in a soil deposit, and then, the findings are referenced in the seismic response of an embankment dam in the west coast of the United States. The shear wave velocities of this embankment dam were carefully selected, using educated judgment, to represent a compacted embankment