Merging criteria for the definition of a local pore and the CSD computation of granular materials: (Paper and Abstract)

Granular filters are materials used to avoid mass transport under seepage flow. They are installed in zoned dams or on the downstream slope of levees to prevent the wash out of soil particles through the core of the earth structures or through its foundation. This migration is stopped if the particles are blocked on their pathway by a constriction smaller than their own size. In that sense, the constriction size distribution is closely related to the filtering capability of the granular filter. Different numerical methods exist to study and divide the pore space into local pores and then constrictions. However, they all require a statement of what a local pore is. Al-Raoush et al. (2003) noticed that the partition of the void space may lead to an over-segmentation of the pore space and merging criteria may be used to define more physical local pores. Conversely, merging may require thresholds that may influence the final degree of the segmentation. In this paper, we compare different merging criteria and discuss their implication on both the local pore definition and the constriction sizes statistical distribution. Moreover, since the constriction size distribution is often used in probabilistic approaches for filtration, we insist on the necessary consistency of the choice of a given merging criterion with other possible statements related to these probabilistic approache