A Discrete Fracture Network Approach to Rock Mass Classification

Abstract

AbstractIn contrast to many disciplines, the approach to design in rock engineering remains largely inductive: observations, experience and engineering judgment are used to infer the behavior of a problem that cannot be constrained due to the nature of geological/geotechnical materials. Most of the rock mass classification systems used for rock engineering design purposes were developed in the 1960s and 1970s; since then no major updates have been proposed to reflect modern data collection tools and modelling procedures. Furthermore, engineers have attempted to apply existing classification systems in the context of a probabilistic design approach despite most of those systems being based on qualitative and semi-quantitative measurements. In this paper, we use a discrete fracture network (DFN) approach to introduce the first component of a new quantitative classification system that can capture rock mass scale, anisotropic effects; and better reflects the degree of connectivity of the natural fracture network. A new network connectivity index (NCI) is introduced that uses areal fracture intensity and density, and intersection density to provide a quantitative description of rock mass blockiness.KeywordsDiscrete fracture networkRock mass classification