Two real cases: the potential effect of an induced infiltration in the vicinity of an embankment founded on potentially collapsible natural silts and the effect of rainfall regime on a canal founded on cemented collapsible silts are discussed. Tests performed to determine the parameters of an elastoplastic constitutive model (BBM) for the unsaturated foundation materials are described. Hydraulic properties were also determined. The two cases are simulated through the computer program CODE_BRIGHT. The calculation scenarios aim at studying limiting cases, to establish the risk of embankment malfunctioning.