Abstract:

Geotechnical block modeling techniques have evolved significantly in past two decades and found ever increasing application in mine planning and design considerations. Starting from preliminary interpolation and extrapolation Rock Quality Designation (RQD), the geotechnical block modeling concept has evolved into full scale detailed geotechnical models that include all elements of geotechnical characteristics of the rock mass like joint number, joint alteration, and joint roughness leading to a representation of more robust rock mass quality indicator Q in the block model. The current work evaluates effects of sample compositing and various interpolation technique like nearest neighbour and inverse power distance methodology on NGI rock mass quality index Q and its respective input. Block models produced using non-composited sample intervals produces a realistic spatial distribution of rock mass quality indicators, but their statistical summary cannot be reliably used due to variable sample support length to the block. Sample compositing, on the other hand, produces reliable statistics but over smoothing of data makes it deviate far from reality and practically non-usable. This paper explores methodologies to effectively utilize geotechnical block model data for mine design and planning processes, specially for the automated planning exercise like ground support design and cost, based on Q values obtained from the geotechnical block model. This is a case study for mine planning exercise in an enriched porphyry copper deposit in western United States within Basin and Range geological province. The geological and structural settings, in combination with substantial conglomerate overburden, presents unique geotechnical challenges for mine design exercise.

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Mr. Todd McCracken