We will be concentrating on the deformability, strength and
failure of intact rock. The emphasis on this subject culminated with
the ‘discovery’ of the ability to obtain the complete stress-strain
curve. The curve provided previously unknown information on the
behaviors of rocks after their peak strength has been reached.
The failure region has special significance in rock mechanics
and rock engineering because, in some circumstances, we can design
an underground structure knowing that the rock will pass into the
post-peak region.