Bayar, E, Simanjuntak, K, Birch, D, Mardiansyah, F & Purwanto, H 2024, 'Seismological data and analysis for the early stages of block caving', in Daniel Johansson & Håkan Schunnesson (eds), MassMin 2024: Proceedings of the International Conference & Exhibition on Mass Mining, Luleå University of Technology, Luleå, pp. 893-908.
(https://papers.acg.uwa.edu.au/p/2435_G-02/)
Abstract: Tracking the development of a block cave yield zone and assessing the condition of the rock mass are key operational objectives in block caving. Oyu-Tolgoi Mine has invested extensively in the application of a variety of well-known technologies used in rock mass deformation monitoring. Among these is a large seismic sensor array consisting of 138 predominantly triaxial sensors with over 400 active data channels. The deployment of deep borehole sensors above the block cave footprint and the use of modern microseismic data processing methods allow for a rich dataset. Data recording started more than 4 years before the first undercut ring and draw bell firing at Panel-0. Thus, providing a complete time history of rock mass response before and after cave initiation. This paper demonstrates the pairing of methods used in mine seismology with complementary data sets from other methods and systems used in cave propagation tracking, such as travel-time tomography and the Cave Tracker and Networked Smart Marker systems. Non-classical microseismic signals that were previously discarded as “low-frequency noise” are characterized and discussed. These sources are interpreted in the context of rock mass degradation induced by yield zone propagation and provide a more complete picture of the observed seismic response. Finally, the development of large shear-type seismic events adjacent to Panel Zero is explained with the use of a mine-scale, 3D numerical model.