Shear Strength Applications in Plastic and Limit Equilibrium - Unsaturated Soil Mechanics in Engineering Practice - page 665

Shear
strength
parameters

Saturated
hydraulic
conductivity

SWCC:
Residual
suction

SWCC:
Residual
saturation

SWCC:
Air-entry value

Precipitation

Low

Low Low Low Low Low

Factor of safety

Nominal

Nominal Nominal Nominal Nominal Mean

Factor of safety

High

High High High High High

Factor of safety

Figure 12.119 Decision Tree for weather hazard model.

in decision programming language (e.g., Applied Decision
Analysis LLC, 1998). Analyses have indicated that precipi-
tation appears to be the single most sensitive variable related
to slope instability, and therefore the quantification of precip-
itation and net infiltration is of high priority.
The weather hazard model attempts to make use of
the principles and properties of unsaturated soils along
with developments in slope stability analyses and decision

theory. A discrete stochastic approach can be used along
with unsaturated soil properties that are related to the
SWCC. A series of partial differential equations governing
the thermo-hydro-mechanical behavior can be used with
appropriate soil-atmosphere boundary conditions to indicate
the likelihood of a slope failure. The primary input to the
slope stability analysis is the pore-water pressure conditions
which change depending upon imposed weather conditions.