Shortcomings in the standard continuum based Implicit Joint model of layered rocks

D. P. Adhikary

CSIRO Earth Science and Resource Engineering, Brisbane, Australia.

E-mail: deepak.adhikary@csiro.au. Tel: +61733274496. Fax: +61733274666.

Accepted 8 February, 2010

 Abstract

Layered rock masses can be described efficiently using a continuum formulation. There are two distinctive continuum based formulations that are found in the published literatures e.g. conventional continuum formulation based models such as Ubiquitous Joint model and non conventional formulation based models such as Cosserat Continuum models. Such equivalent continuum models may provide reasonably accurate predictions when joint slips are minimal i.e. when the shearing is in the direction of layering and rock layer bending can be neglected. However, when joint slips are large and loading direction is not aligned with the direction of layering models based on conventional continuum theories may considerably overestimate the deformation since the bending rigidity of the rock layers are not incorporated in such model formulations. For the case of rock layers with bending stiffness, an Accurate Continuum model can be formulated successfully on the basis of Cosserat Continuum theory. The accuracy of both the Conventional and the Cosserat Continuum models to describe the load-deformation behaviour of the layered rocks is studied in this paper.

Key words: Ubiquitous Joint model, Cosserat model, layered rock, flexural toppling.