Verdal Port Landslide: Slope Stability Back Analysis from CPTU and Finite Element Modelling

Abstract

In January 2019, a shallow marine landslide occurred at Verdal Port, Norway. This slope failure occurred during ongoing construction for port expansion. The initial geotechnical investigations were heavily reliant on CPTU measurements, and misinterpretations of the ground conditions resulted in erroneous slope stability calculations. This paper used a combination of updated CPTU measurements and finite element modelling to perform slope stability back analyses for the Verdal Port landslide. Different CPTU soil behaviour type classification schemes were utilised to produce various soil profiles, that were imported into the software PLAXIS 2D. These finite element models were used to investigate the soil strength parameters, potential failure mechanisms, tidal influences, and geological structure while highlighting the uncertainties associated with CPTU based interpretations and providing an indication of how these uncertainties may influence slope stability calculations.