3D Geological Modeling and Rock Mass Quality in Pongkor Gold Mining, Bogor Regency, West Java Province

Abstract

Stability of rock masses is a critical concern in underground mining, frequently influenced by lithological variations that can reduce rock mass quality. This study presents a three-dimensional (3D) model of lithological distribution and rock mass quality in the study area, constructed using the Rock Mass Rating (RMR) classification system. Implicit modeling was conducted with Leapfrog Geo software, utilizing lithology logging and RMR data as primary inputs. Model validation was performed through face mapping data to ensure alignment with observed ground conditions. The 3D lithology model delineates the presence of lapilli tuff, tuff breccia, andesite, and quartz veins. RMR analysis shows that the wallrock is predominantly classified as class 2 (good rock) and class 3 (fair rock), indicating generally stable conditions. In contrast, quartz veins are mainly categorized as class 3 (fair rock) and class 4 (poor rock), highlighting zones with lower stability. Based on the spatial distribution of RMR classes, appropriate support systems are proposed to enhance ground control. The integration of 3D lithological and RMR modeling provides valuable insights for underground mine planning and support design, contributing to improved safety and operational efficiency in complex geological environments.