Strategic management for squeezing ground conditions at the Argyle Diamonds block cave project

Abstract

The paper elaborates on a methodology of damage assessment based on conditions encountered in the Argyle Diamonds Underground Project (ADUP). It has been developed iteratively over a number of months and has been used to comprehensively represent damage conditions as the undercut front advances. Correlation between damage and convergence has been established. The ground support regime that has been implemented at ADUP to withstand very severe squeezing (Hoek & Marinos, 2000) has produced the outcome that only in limited areas of extreme squeezing (in excess of 20% convergence) has stripping and rehabilitation been required to enable undercutting operations to continue. This issue highlights the importance of the implementation of adequate guidelines to maintain drive stability and safety during undercutting. The long-term and strategic implications of correlating damage conditions with convergence and therefore deformation are that a practical predictive model can be developed. This can then be used to forecast the level of damage that is likely to occur in the undercut drives and extraction level drives based on displacement modelling. This model allows an optimised level of support and reinforcement to be designed depending on the predicted damage conditions. Such a “predictive” model could be used to estimate the optimal level of support and reinforcing (and to establish a realistic budget and schedule for the work), as well as an ongoing tool for forecasting damage conditions (and remedial support and reinforcing) during undercutting and block caving progression.