[ghsc-seminars] Tomorrow, 4/12 @ 2pm: Lorenza Spadoni, University of Camerino, Italy

[Mirus, Benjamin]

*Application of coupled three-dimensional partially saturated groundwater
flow and rigorous three-dimensional stability analysis to assessment of
landslide potential*

*Lorenza Spadoni*
*University of Camerino, Italy *

A majority of the slope stability models represents shallow landslides in
digital landscape and uses the one-dimensional infinite slope stability
method, which neglects laterally constant stress and the effects of
irregular topography. Moreover, the infinite slope method accuracy
decreases when the ratio of slab depth to length increase, which leads to
the over-prediction of unstable areas. In order to overcome these
limitations, the limit equilibrium model was extended to three-dimensional
topographies. In particular, the use of three-dimensional slope stability
analysis based on two-directional moment equilibrium is able to treat
asymmetrical planes and to compute the direction of potential sliding
force.

Moreover, the majority of the slope failures during heavy rainfall are
strongly associated with the increase of the soil saturation, which in turn
cause the decrease in the shear strength of soils. For this reason, the
contribution of the soil water pressure must be properly evaluated in order
to improve the accuracy of the slope stability method. The Richards
equation (Richards, 1931) is one of the main tools for simulating the
three-dimensional water flow in porous media and for this reason its
solution, coupled with a slope stability model, is an effective procedure
to evaluate slope failures.

In this work, we assess the slope stability by using a 3D limit equilibrium
analysis coupled with a 3D groundwater flow model. In particular, we solved
numerically the three-dimensional Richards equation and we use a 3D method
of columns to compute the limit equilibrium analysis of the slip surfaces,
given by the intersection of spherical trial surfaces with the soil columns
defined by a DEM (digital elevation model) grid cells. The performances of
this method are investigated in the assessment the slope stability in the
colluvial basins of the Oregon Coast Range. Comparison of the infinite
slope model against the 3D slope stability one in the observed area
demonstrates the improvement in the accuracy of landslide predictions.


*Thursday, April 12th**, 2018*
*​2​*
*-*
*3​pm*
*​  (Mountain Time)*
*USGS, 1711 Illinois Street, Golden, CO*
*Entry Level Seminar Room*

*Note: Please arrive *~5 minutes early* and *bring photo ID* for
airport-style security measures now in place at the USGS building.

Thank you,
GHSC Seminar Committee

Mirus, Ben - bbmirus at usgs.gov
Josh Rigler - erigler at usgs.gov
Oliver Boyd - oboyd at usgs.gov

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