Potential Cave Shape Interpretation through A Comprehensive Monitoring System at the Deep Mill Level Zone Mine, Indonesia.

ABSTRACT: The DMLZ is a block cave mine with production blocks (PB) are divided into PB1, PB2, PB3 and on going development PB4 at higher elevation. Currently, the caved footprint has reached approximately 200,000 sqm. The caving process in DMLZ has four stages that include cave establishment, cave initiation, cave propagation and cave interaction breakthrough into DOZ, that is part of a surface subsidence zone. The stages of caving process requires appropriate monitoring and evaluation assessments to mitigate any hazards and risks associated with these caving stages. Cave shape modelling and interpretation are essential tasks for ensuring the safety and efficiency of caving operations. This study was aimed at investigating the application of comprehensive monitoring system to enhance the accuracy of the cave shape interpretation and propagation. By integrating best practice techniques such as open-hole camera survey, Elexon System, seismic tomography and HOD, real-time micro-seismic monitoring, TDR and surface subsidence, the cave propagation is monitored continuously. Current development of the PB4 drifts has validated the yield boundary of interpreted potential cave shape, confirmed by the progressive change in ground conditions. This has contributed to helping ensure a safe development phase of PB4 as it drives towards the potential cave shape.