The Effect of Joint Spacing Uncertainty on Landslide Debris Accumulation Features—Insights from a Sedimentary Dip Slope Case

Out of the three sources of model uncertainties (ground, geotechnical, and geologic model uncertainties), geologic model uncertainty was less discussed in geotechnical engineering analyses. In this study, we focused on the effect of geologic model uncertainty, expressed as the joint spacing uncertainty, on the debris accumulation features of a dip slope sliding case. 3D distinct element models were established by incorporating LiDAR digital elevation map and the given joint set distribution. Based on the analysis results, it was found that the crest displacement, run-out distance, and debris coverage width were affected by the variations in dip joint spacing. In contrast, the debris coverage area was affected by the variations in strike joint spacing. Therefore, if the sliding mass run-out risk could threaten the nearby residents or facilities, it is also crucial to consider the joint spacing uncertainty in the corresponding analyses.