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Abstract
Recently, the advent of optical systems has made possible the fast and accurate measurement of roughness discontinuity in three dimensions. In this study, a number of 3D roughness parameters such as fractal parameter (D), amplitude parameter (A), roughness parameter Rs and Grasselli’s roughness parameter (2A0θ*max/(C + 1)) have been presented to quantify the geometry of the fracture surfaces. However, all these roughness parameters are scale dependent and their values change with scale. In this paper, the variations in theses parameters have been investigated with regard to scale. For this purpose, initially, three natural fracture surfaces with the dimensions 500 × 500 mm2 were selected and then, the four mentioned roughness parameters were calculated for these three surfaces in the range from 50 × 50 mm2 to 500 × 500 mm2. Finally, to evaluate the accuracy of roughness estimation by these roughness parameters, several joint replicas from the surfaces were constructed and the direct shear tests were carried out on them. Based on the experimental results, the Grasselli’s roughness parameter gives more accurate estimation of the variations in surface roughness in regard to scale. Also the effect of small-scale evenness on surface roughness has been investigated.
Acknowledgements
The code used in this paper for calculation of roughness parameters has been written by Grasselli’s Geomechanics Group. The authors would also like to thank Govanni Grasselli and members of this group specially Anton Biryukov for their assistance to this study.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
1. Shining 3D OpticScan V2.2 (www.shining3D.com).
2. This code has been written by Grasselli’s Geomechanics Group.
3. Procucted by Soil Mechanics Industry of Iran (SMI).