Stability evaluation of shallow blocks in high and steep slope combining TLS and UAV photogrammetry

Abstract

Failure of rock slopes constitutes a prevalent geohazard inherent to transportation networks and structures situated in high and steep mountainous terrains, resulting in fatalities and infrastructural damage. This study delineates a framework for evaluating the stability of shallow blocks within an intricate alpine topography, including data acquisition, automatic discontinuity extraction and stability assessment of shallow blocks. The proposed methodology leverages composite surveys to generate high-resolution point clouds using terrestrial laser scanning (TLS) and Unmanned Aerial Vehicle (UVA), facilitating the rapid assessment of the shape, volume, and safety factor of unstable blocks by employing an auto-discontinuity extraction algorithm. In case studies, we discovered that the discontinuities orientation of natural slopes and excavated slopes has changed. This discrepancy significantly influences the instability mechanism of these slopes, leading to precise identification of falling blocks after slope excavation, which is particularly prevalent on roads and unsupported slopes. Consequently, the proposed method is of paramount significance for the assessment of slope stability during construction and offers valuable insights for the formulation of safety measures. Furthermore, its potential to facilitate rapid and accurate assessments of rock mass instability hazards and locations underscores its importance in ensuring the stability of shallow blocks in these terrains.