Practical use of the ubiquitous-joint constitutive model for the simulation of anisotropic rock masses

Anisotropic rock masses, the behavior of which is dominated by closely spaced planes of weakness, present particular difficulties in rock engineering analyses. The orientation of discontinuities relative to an excavation face has a significant influence on the behavioral response. At the present time, discontinuum modeling techniques provide the most rigorous analyses of the deformation and failure processes of anisotropic rock masses. However, due to their computational efficiency continuum analyses are routinely used to represent laminated materials through the implementation of a Ubiquitous-Joint model. The problem with Ubiquitous-Joint models is that they do not consider the effects of joint spacing, length and stiffness. As such, without an understanding of the limitations of the modeling approach and detailed calibration of the material response, simulation results can be misleading. This paper provides a framework to select and validate ubiquitous-joint constitutive properties.