ANALYSIS OF ROCK MASS CLASSIFICATION ON MINE SLOPES USING THE ROCK MASS RATING (RMR) METHOD

Abstract

Indonesia possesses substantial mineral and coal resources due to its geological conditions. However, these resources must be used sustainably, as they are non-renewable. In addition, mining activities are required to ensure occupational safety, particularly in open-pit mining operations where activities are highly influenced by the presence of mine slopes (pit slopes). Slope stability is therefore a critical aspect, given the numerous slope failure incidents reported globally resulting from inadequate planning that fails to account for geotechnical conditions comprehensively.

This study aims to analyze mine slope conditions using the Rock Mass Rating (RMR) classification method to determine the rock mass class at the study site. The research employs both qualitative and quantitative approaches, with systematic data analysis based on the RMR method. The research stages include a literature review, field surveys, data acquisition, data processing, and data analysis. Primary data consist of scanline measurements, discontinuity conditions, and groundwater conditions, while secondary data include the rock's Uniaxial Compressive Strength (UCS) values.

The analysis results indicate an average uniaxial compressive strength (UCS) of 1.54 MPa, a Rock Quality Designation (RQD) value of 97.91%, an average joint spacing of 0.45 m, and discontinuity surfaces that are rough with apertures of less than 1 mm and slightly weathered joint walls, as well as groundwater conditions classified as damp. Based on the weighting of all these parameters, a Rock Mass Rating (RMR) value of 66 was obtained, which falls into Class II, corresponding to a good rock mass category. These results indicate that the rock mass quality of the mine slope at the study site is in relatively good condition according to the RMR classification.