ABSTRACT
Recently Vardoulakis (2004) discussed the behavior of granular media in artesian flow conditions. In hydromechanically stable beds, internal mobility of grains is impossible and other phenomena prevail, which are related to the fluidization of the granular bed. Fluidization sets in at a critical hydraulic gradient, at which the seepage force exerted on the grains by the flowing fluid in upwards flow balances their buoyant weight. The critical hydraulic gradient is computed as,
where ϕ is the porosity of the bed and Gs is the relative density (specific gravity) of the grains.
