Fluidisation in artesian flow conditions: Hydromechanically unstable granular media Available to Purchase

The present analysis focuses on fluidisation and erosion processes involving hydromechanically unstable granular materials in artesian flow conditions, as these phenomena were documented in column tests with gap-graded soils by Skempton & Brogan. It is shown that the observed abnormal decrease in hydraulic resistivity can be attributed to fluidisation of the fines fraction of the soil, which eventually leads to unplugging of the pore space and segregation piping erosion in the form of a runaway instability. For the description of the erosion process a continuum theory for three-phase media consisting of stationary grains, transported grains and pore fluid is presented. The governing mass balance and momentum balance equations, and the constitutive law for particle erosion are formulated and discussed in the light of the experimental evidence.