Simple criteria for ploughing and runout in post-failure evolution of submarine landslides

Abstract

This paper extends shear band propagation analysis of slope failures to the investigation of ploughing and runout phenomena in submarine landslides. The ability to predict the two different modes of post-failure landslide evolution is critical for determining the tsunami hazard and type of landslide impact on offshore structures. The proposed analysis is based on the analogy between ploughing and spreading failures. It uses the energy balance approach to develop the criterion for progressive shear band propagation driven by accumulation of sliding material on top of the stable slope. This criterion is then combined with the kinematic passive block mechanism to produce analytical ploughing failure criteria formulated in terms of the critical rise in the seabed level. If the minimum rise of the seabed level at which ploughing can take place is larger than the maximum possible free-standing step in the seabed surface, the first passive failure block will start crumbling over top the stable zone causing the landslide to runout. Application of the derived criteria to the analysis of observed geomorphological features is demonstrated using an example of a paleolandslide complex in the Caspian Sea.

A consistent global approach for the morphometric characterization of subaqueous landslides

“…The interaction of landslides with the underlying stratigraphy, particularly where erosion, ploughing or stepped frontal ramps occur, can further complicate the measurement of thickness and, in turn, the associated calculation of volume from deposits (e.g. Richardson et al 2011;Puzrin 2016).…”

Growth of slip surfaces in 3D conical slopes

“…After reaching a certain critical length, this growth becomes unstable (catastrophic, 8 ) eventually causing active and passive failures at the top and bottom of the slope, respectively, bringing it to a global failure. During subsequent landslide evolution, the moving mass may either run‐out or plough into the intact ground at the bottom 9 and produce recurring upslope retrogressive failure at the top of the slope 10,11 . These post‐failure phenomena explain the devastating dimensions of the underwater mass movements and their extent has been quantified by simplified analytical solutions, 9,12 limit analysis 3,13 and numerically 14,15 …”

“…During subsequent landslide evolution, the moving mass may either run‐out or plough into the intact ground at the bottom 9 and produce recurring upslope retrogressive failure at the top of the slope 10,11 . These post‐failure phenomena explain the devastating dimensions of the underwater mass movements and their extent has been quantified by simplified analytical solutions, 9,12 limit analysis 3,13 and numerically 14,15 …”

Lagrangian modelling of large deformation induced by progressive failure of sensitive clays with elastoviscoplasticity

“…where cohesion softening is adopted to capture the basic post-failure behaviour. Following [33,34], the strain-softening behaviour is accounted for by reducing the cohesion c u using a bilinear function ( Figure 1) (13) in which ij is the Kronecker delta.…”

“…However, ignoring the rheology of sensitive clays may lead to the inaccurate predictions. Analytical approaches, such as shear band propagation approaches [12][13][14][15], have also been used to study the progressive failure process in catastrophic landslides in nature. Recent developments in the shear band propagation approach for analysing catastrophic and progressive failure are summarised in [16].This paper provides an alternative Lagrangian computational approach for the analysis of progressive failure of sensitive clays involving extremely large deformation.…”