Engineering Rock Mechanics

Additional points 87

Panel A

Panel B

6.3 Additional points

Although a failure criterion based on the physical mechanisms of failure
might be expected to exist, this has not yet been developed because
of the structural complexities of both intact rock and rock masses, and
the progressive nature of failure. Because the development of such
a criterion is not yet practical, the empirically based failure criteria
expressed in terms of stress are now used ubiquitously.