A Cyclic Design Framework for Assessing Seismic Stability of Submarine Slopes

1. Home
2. Publications
3. Online Library
4. A Cyclic Design Framework for Assessing Seismic Stability of Submarine Slopes

An optimised design framework is proposed for quantifying risks to offshore deep-water developments associated with slope instability induced by seismic loading. In this framework, screening-level assessments are first conducted to identify the most critical slopes using upper bound limit analysis with rigid-plastic soil models and pseudo-static methods applying equivalent pseudo-static seismic forces to the slopes. However, real seabed sediments on slopes are ductile and experience a highly non-linear stress-strain response before full mobilisation. Upon continued straining, the soil may also experience post-peak softening due to remoulding after the peak shear strength is mobilised. In a seismic event, the cyclic strains accumulated by the soil may accumulate sufficiently to exceed the threshold required to initiate unconstrained catastrophic failure under the static loads alone during or after the earthquake.

A suite of dynamic finite element (FE) analyses is presented in this paper considering critical soil responses such as soil consolidation-induced anisotropy, cyclic degradation considering cyclic loading characteristics, soil remoulding and strain rate enhancement effects. This paper presents an example application considering both 2D and 3D seismic slope stability analyses.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

1 - Site investigation strategies, geohazards and integrated studies