Abstract:
This study is concerned with a theoretical, laboratory and in situ investigation
of the propagation of seismic stress waves through soil media.
Analyses are carried out to predict the surface response that results from earthquake
motions being transmitted through the upper layers of the earth. The nature of the near
surface geological layers affect to a marked degree the intensity of surface motion. The mathematical
models presented are used in the evaluation of site response to earthquakes.
The theoretical methods used depart from the traditional viscoelastic approach
and use a nonlinear hysteretic soil model to describe the complex dynamic stress-strain relationships
evident in soil response. The dynamic soil model is based on previous laboratory work carried
out at this university.
The theoretical solutions formulated are limited to one-dimensional situations.
Three methods of analysis are presented for the propagation of seismic shear waves through nonlinear
soil media and conclusions are drawn as to the best approach. The results of these analyses are
generally significantly different from those obtained using a viscoelastic soil model. Seismic
dilatational waves are also considered important and a method is presented to calculate the response
of hysteretic soil media to these disturbances. The outcome from these dilatational and shear wave
analyses is more accurate surface response spectra for use in aseismic structural design.
