Rock Strength and Yield

Abstract

The concept of rock strength or strength failure as a result of laboratory testing is difficult and complex to define. Stated most simply, rock strength is the peak stress in a uniaxial or triaxial compression deformation process. During this process there is no unique point at which rocks fail or collapse. The same is equally true in the vicinity of most structures in rock. A hole in the ground represents a small opening in a large continuum. Energy released by fracturing at a part of the structure is rapidly accommodated in the continuum. Only in the case of isolated pillars or the edges of plates in the earth’s crustal structure do the conditions exist for rapid release of energy — in exceptional forms such as rockbursts or earthquakes.