Development of rock mass strength block models at Cadia East mine

Abstract

Block models of rock mass strength have been developed at Cadia East mine to support forecasting of excavation performance. This paper describes four key aspects of the workflow that have enabled forecasting of rock mass strength throughout the entire orebody: 1) high density measurements of the spatial variability in intact and defected rock strength, derived from systematic point load testing of core from select boreholes; 2) continuous estimates of core-scale rock strength along all boreholes (including those with no or low density testing), enabled by application of machine learning to all available geological and geotechnical data, 3) estimation of tunnel-scale rock mass strength from the local statistical distribution of core-scale strengths, enabled by synthetic rock mass (SRM) testing, and 4) development of an integrated litho-structural model and the implementation of a structural trend to estimate block variables.

Numerical forecast of central access ground support behaviour at Cadia East PC1-2

“…Figure 5 BBM constructionCadia has an extensive database of PLT data covering a large extent of the PC1-2 footprint from systematic borehole logging and the subsequent machine learning study. A description of the geotechnical block model for Cadia is given inPierce et al (2022) and typical ranges of rock mass strength at different scales for Cadia are reported inFuenzalida et al (2022). Based on the distribution of Weibull PLT data parameters (rolling average within 30 m window) along the boreholes in the vicinity of the central access, a set of parameters was selected to be representative of a large extent of the central access based on the geotechnical block model.…”