Abstract
One of the first tasks to execute prior to the geotechnical characterization of a rock mass is define the Geotechnical Units that compose it. The most widely used and accepted methodology in the mining industry indicates that a Geotechnical Unit is defined by the superposition of lithology, alteration and mineral zone, where the use of the latter is related to the differentiation between the environment of primary and secondary mineralization.
Although this methodology may seem very easy to apply, two issues seem to repeatedly appear when reviewing various mining projects. Firstly, various projects show only a partial implementation of the method, considering merely the lithology or the combination of lithology and alteration when defining Geotechnical Units. Secondly, in those projects in which mineral zones were also considered, these were mostly defined according to mineralogical or even metallurgical criteria that do not necessarily coincide with geotechnical quality criteria.
The purpose of this paper is to present a clear methodology for the definition of Geotechnical Units in a rock mass based on the concept of Geotechnical Zones, instead of mineral zones, to avoid confusion between mineralogical and/or metallurgical criteria and geotechnical criteria.
As an example, geotechnical characterizations of rock masses are shown according to the proposed methodology and how it manages to better differentiate the geotechnical qualities between primary and secondary rock masses.
