Probabilistic Runout Analysis Of The Gjerdrum Sensitive Clay Landslide Using The NGI-ADPSoft Model

In this study, Material Point Method (MPM)-based simulation is performed to investigate the runout behaviour of the recent sensitive clay landslide in Gjerdrum, Norway. The NGI-ADPSoft material model is employed in the MPM simulation to capture anisotropic undrained shear strength that is reduced after peak with increasing shear strain until the anisotropic residual shear strength is reached. Simulation results of the Gjerdrum landslide show that the shear band progressively formed along the sensitive clay layer and are comparable with field observations. Peak and residual shear strengths are considered as random variables following lognormal distributions. Monte Carlo simulation is used for probabilistic runout analysis of the Gjerdrum landslide.It suggests that variability in undrained shear strength significantly affects runout. The runout distance and the area affected by the landslide have strong negative linear correlations with the peak shear strength. Empirical formulas are fitted to predict the runout distance and affected area from the peak shear strength. Overall, this study provides a good demonstration of large deformation modelling of sensitive clay landslides considering uncertainties for risk assessment.

Keywords: Sensitive clay landslides, Probabilistic runout analysis, MPM, NGI-ADPSoft model, Uncertainties.