Rock slope investigation using photogrammetry data

This paper outlines the application of structure from motion (SfM) photogrammetry technique with the use of smartphone camera to acquire a three-dimensional (3D) rock slope surface model to perform kinematic analysis and slope stability analysis. The location of the study slope is in a construction site at Jalan Inanam, Sabah. Total of 63 images of the study slope were used to construct the slope geometry and geological mapping was carried out on it to measure the spatial orientations of the discontinuity planes. These orientations were imported into Rocscience Dips to perform kinematic analysis, while the geometry was imported into Rocscience RS3 to perform finite element rock slope stability analysis. The results show that majority of the slope regions will likely experience wedge sliding and flexural toppling failure. The weakest rock region is on the crest of middle region of the rock slope with a factor of safety of 0.48 and total maximum displacement of 0.56mm. The rock region is subjected to possible flexural toppling failure. The results obtained shows that SfM photogrammetry is competent to simulate the slope geometry which accurately resembles the actual slope. The spatial orientations measured using ShapeMetrix3D are deemed to be reliable to use for kinematic analysis. Furthermore, slope stability analysis using RS3 and RS2 is able to accurately determine the factor of safety of the potential failure rock slope surface.