Evaluating the correlation of rock mass classification systems in volcanic lithologies: a case study in a vein-shaped mining district at central Chile

Abstract

Defining engineering behavior of rock masses is strongly dependent on observations made in situ and the following rock mass geotechnical classification. Nowadays, the most widely used classifications are rock mass rating (RMR) and the rock mass quality (Q). Because the rock mass characterization is normally done in terms of one (or rarely more than one) of these systems, and because different mechanical assessment tools used in this and later stages of mining design are typically expressed in any of the systems, it is important to be able to properly correlate rock mass classification ratings in at least the most used rock mass classification systems. In this paper new relationships for correlation of mentioned ratings are proposed. Data used was collected from active mines at Chépica mining district, located in the Maule region of central Chile. Results are compared with similar proposals from various authors and statistically evaluated to show that the proposed correlation equation is accurate and useful when applied to volcanic lithologies with rock masses in the range of fair to good.