...( , , ) ( ) ( ) = + 2 (4) The Mohr-Coulomb form of the plastic poten- tial is maintained as: g K K r r( , , ) ( ) ( ) sin ( ) sin ( ) = = + and 1 1 (5) where is dilatancy and the plastic parameter is = p p rp. To define the behaviour we can consider piecewise linear functions...

... angle for rock and rock masses is proposed. It includes marked dependencies on confining stress and plastic parameter - plasticity already suffered by the rock - following different trends coinciding with those already observed in compressive tests and rock masses by different authors. It also includes...