Rationalizing the seismic coefficient method
Hynes, Mary Ellen.; Franklin, A. G. (Arley G.)
Miscellaneous PaperAbstract: The seismic stability of embankment dams may be evaluated by a relatively simple method, originally proposed by N. M. Newmark, in cases where there is no threat of liquefaction or severe loss of shear strength under seismic shaking. This method is based on idealization of the potential slide mass as a sliding block on an inclined plane which undergoes a history of earthquake-induced accelerations. The result is a computation of the expected final displacement of the block relative to the base. A necessary refinement is the consideration of amplification of the base motions in the embankment, which is evaluated by means of a linear elastic analysis. Sliding block analyses have been done for 348 horizontal components of natural earthquakes and 6 synthetic records. These computations, together with available results of amplification analyses, suggest that a pseudostatic seismic coefficient analysis would be appropriate for embankment dams where it is not necessary to consider (A.) liquefaction or severe loss of shear strength, (B.) vulnerability of the dam to small displacements, or (C.) very severe earthquakes, of magnitude or greater. A factor of safety greater than 1.0, with a seismic coefficient equal to one-half the predicted bedrock acceleration, would assure that deformations would not be dangerously large.
Geotechnical Laboratory (U.S.)Engineer Research and Development Center (U.S.)
Dams; Embankment dams; Earth dams; Earthquakes; Earthquake engineering; Seismic analysis; Seismic coefficient method; Hydraulic structures; Mathematical model; Numerical models
Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; GL-84-13.
Approved for public release; distribution is unlimited.