2D and 3D rock slope stability assessment using Limit Equilibrium Method incorporating photogrammetry technique

Advancements in technology have made it possible for acquisition and analysis of geological structure data in a short time, cheaper and safer than traditional method. Engineer sometimes failed to model the actual slope geometry due to the factor of accessibility and carry out those measurements at site. But with the aid of UAV photogrammetry technique, they can easily export the 3D model into any slope stability assessment software to perform the analysis. Photogrammetry is a technique used for rock slope assessment. Recent progression in modern UAV technologies such as photogrammetry technique using georeferenced UAV imagery allow us to obtain accurate surface profile including detailed slope information for the three-dimensional stability analysis. These techniques also mitigate the risks at site associated with conventional method. Large number of three dimensional coordinates in the form of dense cloud point can be extracted from only a few images. Dense cloud point imported to the Rocscience Slide version 2018 and Slide 3 version 2017 which is a 2D and 3D limit equilibrium slope stability software that evaluates the factor of safety (FoS) of circular or non-circular failure surfaces of soil or rock slopes. The rock slope parameters are obtained via laboratory test and rock database in Rocscience RocData were used in the assessment. Probabilistic method is performed to compute the 2D slope stability according to the normal distribution of the rock parameters on the global minimum slip surface. FoS of slope analysed by probabilistic method is 0.336 for least and 0.596 for mean FoS. Deterministic analysis is carried out to compute the 3D slope stability and the outcome are global minimum slip surface and the FoS of the entire rock slope. FoS of the rock slope without anisotropic plane is 1.960 and with anisotropic plane is 0.908. Thus, the use UAV to acquire 2D and 3D model of the rock slope is possible and stability analysis can be carried out to generate FoS of the slope as preliminary characterization