Use of multisensor and multitemporal geospatial datasets to extract the foundation characteristics of a large building: a case study

The assessment of the ground conditions for large buildings is important because the results are sensitive to the ground conditions, especially differential settlement. Additionally, slope stability also becomes crucial for buildings constructed on steep terrain. In this study, the foundation characteristics of a seven-story conservatory building constructed on a moderately steep slope on the Beytepe Campus of Hacettepe University (Turkey), and the shallow slope failures developed in the fill were evaluated by using geotechnical analysis methods, including limit-equilibrium and 3D numerical analyses, with the help of multisensor, multiresolution, and multitemporal photogrammetric datasets obtained before and after the construction with high spatial density and accuracy. The photogrammetric datasets taken from airplanes and unmanned aerial vehicles (UAVs) were employed to analyze the ground conditions in 2015 (before construction was started), 2018 (after the building was completed, when slope failure started), and 2019 (to monitor the most recent state of slope failure). Additional ground points were surveyed using Global Navigation Satellite System (GNSS) instruments in 2019. The results of the analyses performed in the present study show a consistency with the in situ conditions. Consequently, the geo-information technologies and photogrammetric datasets used here are very practical and provide accurate data to analyze the pre- and postconstruction states and the deformations of large buildings and their surroundings. The geoinformation-based methodology followed in the study is promising for undisturbed investigations of many geotechnical and engineering geology problems.