Ricerc@Sapienza

This paper concerns the hydromechanical stability of partially saturated soils
during wetting. The response of a loose silty sand is numerically/theoretically
investigated with the main aim of identifying both triggering mechanisms
and predisposing factors to instability. This latter is testified by both a rapid
increase in the pore water pressure and an unexpected loss of numerical
convergence. The study has been conducted at different scales from laboratory
tests to boundary value problems, and in both cases, the controllability theory

The paper addresses the problem of optimal
control design in presence of singular solutions. For this case, a
procedure for avoiding the integration of the costate dynamics
is proposed, giving the conditions under which the costate
can be directly computed, under controllability condition for
the dynamics, and presenting an approach for extending this
property by a dynamic extension. The procedure is here
described for a single input systems and for the case in which
the first step of the iterative procedure is sufficient to get the