Safety Factor Plan Based on Predicted Progressive Failure Surface Under Elasto-Plastic 2D-FEM: A case study of Nuta-Yone Landslide Clusters, Shikoku, Japan

Abstract

This paper deals with slope stability problems of Nuta-Yone landslide clusters, Shikoku, Japan with the aim
of exploring reliable stability factor in 2-dimensional (2D) domains with finite element method (FEM) for the
effective implementation of landslide stability enhancement measures (LSEM). The research enlightens
the stability accuracy impact factors with the use of minimum 1500 elemental budgets in 6-noded uniform
triangular meshing element with quality meshing, the non-linear tolerance of 0.001 and maximum iteration
of 500 employed to get a constant value of the safety factor in 2D modeling domains chosen for different
landslide blocks under Nuta and Yone clusters. Then, the safety factors, thus obtained with aforesaid criteria
seem to be reliable as per the material properties and slope models supplied. Confirming all those factors, the
safety factors, thus obtained can be encouragingly used in effective design and implementation of various
LSEM projects. Moreover, a complete water drawdown effect before and after the LSEM gives a complete
sense of the effectiveness of the measures itself. In addition to this, pseudo-static seismic soil slope stability in
some unstable blocks from Nuta and Yone clusters shows that most of the landslide blocks are unstable in the
seismic soil slope stability even in final ground water table. The identification of progressive failure surface and
the application of mitigation measures based on the unstable shear zone of the landslide slopes, especially for
the collecting wells have a significant effect to enhance the stability of landslide slopes. The safety factor plan
thus designed for the stability of Nuta-Yone landslide clusters based on the factored safety factors that would
be fixed for the utility and the existing stability condition of the whole landslide clusters.