Seismic shear strains and seismic coefficients in dams and embankments

In a previous publication¹ dealing with the lateral seismic response of dams and embankments the authors developed an inhomogeneous shear beam (SB) model in which the modulus increases as a power m of the depth, with m ranging from 0.35 to 0.90 and depending on material and geometric parameters. Reference 1 studied primarily the free vibration characteristics and the distribution of peak seismic displacements in earth dams. This paper focuses on seismic shear strains and stresses, and on seismic coefficients. Both steady-state and transient vibrations are considered and the effects of inhomogeneity are graphically illustrated. A comprehensive comparative study is undertaken using five dam cross-sections, each excited by four recorded accelerograms. It is found that plane-strain finite-element analyses yield distributions of peak values of seismic shear strains which, in general, are in good accord with the results of a ‘consistent’ inhomogeneous SB model. The limitations of the developed model are also elucidated and possible ways of overcoming them are suggested.