DYNAMIC FAILURE OF JOINTED STRATIFORM ROCK BODIES

Abstract

Ryan and Mall studied antiplanar oscillations of a layer containing a crack of finite length in its midplane. They proved by numerical calculations that the crack resonated at specific frequencies. Unfortunately, because they accepted a high level of error (1 percent) in their computations, it is impossible to determine from their results whether all of the resonances that they found were unbounded and led to failure. In the present paper, in dealing with the planar and axisymmetric cases, the new approach is taken of subdividing the resonances of cracks and cavities in a layer into low-frequency and high-frequency types, depending on the characteristics of the vibrational process. These two types are investigated and the crack characteristics that result are unbounded resonances are identified.