STABILITY ANALYSIS OF MINE TUNNEL USING RMR, Q-SYSTEM, AND FINITE ELEMENT METHOD IN UNDERCUT LEVEL, GBC MINE, MIMIKA, PAPUA

• Main Author: Chandra Bhakti, Novika
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/46769
• Institution: Institut Teknologi Bandung

Grasberg Block Caving (GBC) mine is undergorund mine located in Gunung Bijih District Mine, Mimika, Papua. The research was conducted in west access 3 to north from west fringe drift tunnel in undercut level located at elevation about 2,845m. The objectives of this research were to obtain mass rock rating based on RMR and Q-System, to get ground support recommendation based on RMR value and Q value, and to analyze the stability of supported tunnel obtained from RMR method and Q-system. The research area consisted of Intermediate Intrusive Dalam Phase Rock emplaced approximately at Pliocene and strongly altered composed of sericite, secondary quartz, pyrite and covellite. RMR value of the rock mass were ranging from 53 to 65 classed from Fair to Good class, while Q value were ranging from 0.1 to 0.35 classed as very poor class. RMR method recommended to support the tunnel with rockbolt, shotcrete and wiremesh, while Q method recommended to support it with rockbolt and fibrecrete. Strength factors of Q-recommendation supported tunnels were always above 1.2 while RMR-recommendation supported tunnesl were not always have SF above 1.2. Displacement total of RMR-recommendation supported tunnels was ranging 6.6 – 8.5 mm at roof dan 5.7 – 7.7 mm at wall, while Q-recommendation tunnels were ranging 6.3 – 8 mm at roof dan 5.8 – 7.7 mm at wall. Finite element model analysis showed Q-recommendation support was suitable for west access 3 to north from west fringe drift tunnel.