Improving the Consistency of Joint Roughness Estimation in Drill Core with a Visual Guide

ABSTRACT: Describing joint roughness is a key step in rock mass characterization. Geotechnical logging of drill core is a common method for collecting discontinuity data that may be used to estimate joint roughness. This activity is commonly completed by practitioners with limited engineering geology or rock mechanics experience. Results within a single project or campaign may be poorly calibrated across practitioners. Inconsistent results between projects also occur as different methods may be employed without an understanding of how the semi-quantitative indexes and qualitative terms correlate with each other. We present a visual photographic reference tool that has been developed to improve the estimates of joint roughness when logging core. The tool includes correlations between JRC, Jr, and qualitative descriptors. Photographs capture the range of conditions that are commonly encountered across multiple rock types, rendering this tool applicable to a variety of different project settings.