Application of Digital Photogrammetry in Geotechnics

Acquiring geometric data, such as coordinates, displacements or deformations, has always been a way to verify mathematical modelling in civil engineering. The introduction of finite elements methods further reinforced this trend. This paper reports on two applications of photogrammetry to soil and rock mechanics in order to provide an accurate and dense description of the deformation fields of sand specimens in different loading conditions. In the first case, the displacements induced by a foundation under load in sand layers are traced until the collapse of the terrain with accuracies in the order of about 20 micrometers in object space. In the latter, the trajectories of particles, tied to a sloping sand specimen that slides along a plane, are determined with an accuracy of about 3 mm at a rate of 22 fps. In both examples, the measurement runs automatically, the only interaction required being the test setup.