STRESS WAVE EFFECTS IN INHOMOGENEOUS AND POROUS EARTH MATERIALS

The studies described in this report are directed to the construction of reliable techniques for calculating stress wave propagation in a geologic medium in the pressure range from 300 kbar down to a few bars. The medium is considered to be a composite consisting of rock matrix with water in its pores and a description of its wave propagation characteristics is sought in terms of the behavior of the isolated rock and water components. Nevada tuff is selected for the rock matrix in order to be specific in formulating its equation of state from available experimental data. The equation of state for water is constructed in convenient analytic forms for the expanded and condensed states as well as the transition through the steam dome. The shock pressure of saturated wet tuff media with varied mass fractions of water is treated under three assumptions related to the homogeneity of the media 1 complete homogenization--equation of state for wet tuff is calculated under the assumption that the water and tuff components are in local pressure and thermal equilibrium 2 no homogenization- -detailed wave propagation calculations for composite watertuff configurations of varied substructure and 3 theory of interacting continua.