Modeling Landslides with a Material Instability Criterion - Multiscale Geomechanics: From Soil to Engineering Projects - page 233

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Figure 8.12. d 2 W n isovalues for distinct water level (in dashed line)

effect, although small at the surface under a low slope, manages to override the level of
the suction imposed. After this loading step, affected zones develop in depth because
water pressure increases beyond the confinement imposed by gravity. When the water
table level reaches 96% of the maximum height, convergence of the computation is lost.
It can be assumed that, at this step, effective failure occurs because the plasticity limit
has been reached at several integration points. Furthermore, isovalues of the normalized
second-order work permit us to correctly describe the slip surfaces observed in situ .

The criterion for being able to pronounce the global stability of the body is none
other than the second-order work integrated over the total volume as in equation [8.2].
From a numerical point of view, this integration is done as follows:

npi

nel

D 2 W =

t

dσ ij dε ij dV = dσ k .dε k .ω k .j e [8.32]

V

e=1 k=1

with:
- nel the number of elements;