Estimates of crack density parameters in near-surface rocks from laboratory studies of core samples and in-situ seismic velocity measurements

Abstract

A comprehensive theory of the elastic behaviour of cracked and porous solids has been derived by O'Connell and Budiansky. A summary has been given of those portions of the theory that are useful in the interpretation of seismic velocities, measured both in the laboratory and in the field , in ternis of crack or fracture densities and fluid content. Numerical estimates of these crack parameters and the associated errors have been derived from both field and laboratory data. The results emphasize the importance of being able to measure reliable S wave velocities. The relevance of the theory to the study of potential radioactive waste disposal sites has been discussed, and a strategy for future studies has been described.

On the generation of P and S wave energy in crystalline rocks

“…The study of shear-wave propagation in crystalline rock bodies that are being tested during the Concept Assessment phase of the Canadian nuclear fuel waste management program may provide valuable supplementary information on P wave data for the study of the distribution of cracks, fractures and faults (Wright and Langley 1980). A limited quantity of useful shear-wave data was obtained in October 1977, in a gneiss-monzonite rock body at Chalk River, Ontario, using the shear-wave gun designed by R. Turpening .…”