Stability assessment of coastal cliffs incorporating laser scanning technology and a numerical analysis

Abstract

We investigated the cliff coast in Jastrzebia Gora, Poland. The measurements that were taken between 2014 and 2018 by applying terrestrial, mobile, and airborne laser scanning describe a huge geometric modification involving dislocations in a 2.5 m range. Differential maps and a volumetric change analysis made it possible to identify the most deformed cliff's location. Part of the monitoring of coastal change involved the measurement of a cliff sector in order to determine the soil mass flow down the slope. A full geometric image of the cliff was complemented by a stability assessment that incorporated numerical methods. The analysis showed that the stability coefficients, assuming a particular soil strata layout and geotechnical parameters, are unsafely close to the limit value. Moreover, the numerical computations, which were performed under simplifying assumptions, were not able to capture a multitude of other random factors that may have an impact on the soil mass stability. Thus, displacements of both reinforced soil and gabions were detected that are intended to prevent the cliff from deforming and to protect the infrastructure in its vicinity. The array of applied measurement methods provides a basis for the development of research aimed at optimization of applied tools, safety improvements, and a rapid reaction to threats.