ANALYSIS OF THE INFLUENCE OF CAVE PROPAGATION ON CHANGES IN DIRECTION AND MAGNITUDE OF STRESS IN THE UNDERGROUND MINE OF DMLZ (DEEP MILL LEVEL ZONE) AT PT FREEPORT INDONESIA

• Main Author: Richard Rumbekwan, Ronaldo
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80438
• Institution: Institut Teknologi Bandung

The underground mining operation at DMLZ in PT Freeport Indonesia faces challenges in implementing the Block Caving mining method. The primary issue encountered in Block Caving at DMLZ is the change in direction and magnitude of stress due to the growth of Cave Propagation resulting from mining advancement with blasting activities in the Undercut and APEX areas. Monitoring Cave Propagation, previously conducted using Drillholes and TDR (Time Domain Reflectometry) cables, is no longer accurate due to the increasing size of the cave. Because of these constraints, research is needed to determine the stress direction in the research area using Focal Mechanism and Numerical Model methods. The aim is to determine the magnitude of induced stress around the cave in the research area. The analysis results show that the stress trajectory around the DMLZ cave is dominated by the principal stress sigma 1, while the stress sigma 3 tends to diminish. According to the numerical analysis and focal mechanism results in the top area of the cave, the wall area of Section A in the NW direction, and the area of Section B in the SW direction, they tend to have similar plunge values (tilt direction), where the stress direction moves vertically from the top to the bottom of the cave (abutment). However, the focal mechanism analysis results for Section B in the NE direction differ from the numerical results due to the influence of regional structures, resulting in seismic slip caused by the structures operating in that area.