Fumitoshi IMAIZUMI, Hideji MAITA and Kuniaki MIYAMOTO
We need to predict the timing, location, and volume of landslides for the better
disaster mitigation and the better estimation of the bed deformation of mountainous
rivers. However it is not so easy because a number of soil parameters, e.g.,
the angle of internal friction, cohesion, and porosity, are needed to predict
landslide occurrence, and they have significant spatial variability. Therefore,
it is important to make clear how the parameters contribute to overall slope
stability and relate to each other. Few studies evaluated the contribution of
each parameter to slope stability based on the slope stability analyses. However,
they could not give us how landslides would be subject to the set of the parameters.
In this study, we tried to understand it. We, therefore, normalized the safety
factor equation for infinite slope, and introduced laminar soil layer structure
into the equation. Then, we obtained new non]dimensional representation for
the effects of underground water table and cohesion of soil. They are evaluated
relatively with comparison to the stability of dry non]ohesive soil. And we
also obtained that the effect of cohesion of soil should be evaluated from the
comparison with the maximum effect of underground water table to the stability.
From these explanations, we deduced the thickness of landslide, the immunity
to the occurrence of landslide and the periodicity of landslide occurrence.
Key wordsFshallow landslides, infinite slope model, dimensionless parameters