STABILITY ANALYSIS OF UNDERGROUND OPENING DUE TO BLASTING ACTIVITY OF UNDERCUT AT DEEP MILL LEVEL ZONE UNDERGROUND MINE, PT FREEPORT INDONESIA

• Main Author: Razak, Supardi
• Format: Theses
• Language: Indonesia
• Subjects: Pertambangan dan operasi berkaitan
• Online Access: https://digilib.itb.ac.id/gdl/view/54380
• Institution: Institut Teknologi Bandung

PT. Freeport Indonesia (PTFI) is conducting mining activity of copper and gold deposit in Papua, Indonesia. One of the mining sites needs attention of the company is Deep Mill Level Zone (DMLZ) underground mine particularly blasting activity of undercut level. In blasting activity, there are parts of the energy passthrough the rock masses in the form of vibration. The ground vibration could affect the stability of underground opening and may lead to collapse. In this study, ground vibration data obtained from field measurement was calculated to obtain the Peak Particle Velocity (PPV). The field measurement was carried out from 30 March 2019 until 07 May 2019. Data analysis was performed using regression linear scaled distance following equation from USBM (Duvall & Fogelson, 1962) Langefors and Kihlstrom (1963), and Ambraseys-Hendron (1968). Evaluation the effect of blast vibration to the underground opening was performed by numerical simulation using RS2 from Rock Science. First, the numerical results were validated by the actual data. The results of numerical simulation with input parameter of 2% damping ratio shown that the calculated PPV was not significantly different with the actual PPV. The calculation results revealed that PPV of 68,15 mm/s was generated by 70,0 kg explosive charge. This amount of charge equal to 4,67MPa blast load. The calculation results also shown that the stability of the lower opening tunnel is in safe condition with safety factor greater than 1.00.