How to incorporate variability of rockmass structures into equivalent continuum numerical models using the Composite Geological Strength Index

Abstract

The Composite Geological Strength Index (CGSI) is an innovative solution for quantitative rockmass characterization that first considers rockmass structures individually and then calculates a single CGSI value for the whole rockmass. The application of CGSI is to replace the GSI parameter in the Generalized Hoek-Brown shear strength criterion for equivalent continuum numerical modelling. Although originally developed for rockmasses with veins and other intrablock structures, CGSI can be used for any rockmass with disparate structures. In this paper, CGSI is newly expanded to two approaches: Approach 1 is based on block volume of structure suites, while Approach 2 is based on spacing of structure sets. Examples are shown for each approach using igneous and sedimentary rockmasses, respectively.