Determination of onset of failure of rocks in multiple failure state triaxial tests using scale-based differential geometry

This study presents a new method of estimating onset of failure points in multiple failure state triaxial tests of different rocks. This is done by extracting curvature landmarks and their invariant extensions using a scale-based differential geometry approach on the load-displacement curves. Altogether, the load-displacement data of 165 cored samples of different rocks including Norite, Granite, Limestone, Sandstone, Siltstone, Marble and Halite were used during this study. It has been proved that identifying invariant signatures/features of a load-displacement curve results in locating the onset of failure points with acceptable degree of accuracy.