A model to estimate the dilatancy angle of rock masses

The present paper responds to the poor treatment given to dilatancy in classic rock mechanics post-failure problems such as tunnel or mine pillar design. An empirical based formulation to estimate the dilatancy 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 an indirect scale effect. The model presents the advantage that dilatancy is estimated by only one parameter, taking however into account plasticity and confinement stress dependency. In this way the modeler must include among their inputs a reasonable approach of this parameter instead of a constant, and then more or less unrealistic, value of the dilatancy angle.