New approach to quantifying rock joint roughness based on roughness mobilization characteristics

This study explores the effect of normal stress levels and asperity scales on roughness mobilization characteristics through joint shear tests, and suggests a new method for quantifying rock joint roughness. Two-dimensional joint surface profiles were scanned by using a digital camera-based 3D scanner system, and were classified into a small scale of roughness (unevenness) and a large scale of undulation (waviness). Joint surface profile specimens, duplicated using a wire-cut electric discharge machining method, were tested for shear behaviors. For waviness showing non-stationary signals, the mobilized roughness is not constant but varies nonlinearly at normal stress levels. However, for unevenness showing noise and a stationary signal, the ultimate shear strength appears at a low normal stress level.