Visualising bias of structural orientation data

Authors: Thomas, RDH Download Paper

DOI https://doi.org/10.36487/ACG_repo/2135_0.02

Cite As:
Thomas, RDH 2021, 'Visualising bias of structural orientation data', in PM Dight (ed.), SSIM 2021: Second International Slope Stability in Mining, Australian Centre for Geomechanics, Perth, pp. 11-26, https://doi.org/10.36487/ACG_repo/2135_0.02



Abstract:
Structural discontinuities represent an essential component of the geotechnical model for rock slope design. The bias associated with structural orientation data collected from different sources is reviewed, and existing methods of understanding and overcoming this bias are discussed. An alternative method of visualising the bias is presented. This method can be applied to single drillholes, datasets derived from multiple drillholes and scanlines, face mapping or combinations of multiple sources (e.g. a combination of drillholes and mapping data). The method provides a graphical presentation of the structural orientation bias within the selected dataset. The visualisation allows identification of areas of the stereonet in which discontinuities may be under-represented and enables consideration of potential methods to reduce the associated bias. The technique assists the geotechnical designer in understanding whether datasets selected for geotechnical analysis are representative and provides an opportunity to account for the bias.

Keywords: structural data, orientation bias, stereonets, Terzaghi correction, sampling weight

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