Understanding the Impact of Alteration on Rock Mass Strength

Abstract

Rock mass characterization is the cornerstone of informed engineering analysis and design. Consequently, it is imperative to have access to quality data and understand the implications of mischaracterization and uncertainty of collected geotechnical data. This paper presents the results of an investigation on the influence of alteration on the mechanical properties of a rock mass. Field data from an underground hard rock mine illustrated that variations in type, fabric and intensity of alteration had a significant influence the rock mass strength as reported by point load testing. An analysis of alteration data systematically collected from core logging provided valuable insights on the impact of alteration on the strength anisotropy of the rock mass. The spatial distribution of foliation planes and the type, fabric and intensity of alteration varies significantly in the mine. The impact of alteration on rock mass strength contributed to areas of high convergence and high seismicity during mining.