Geotextile filters in unsteady flow conditions



This paper deals with the use of geotextiles as filters in geotechnical engineering, with a special regard to hydraulic and coastal structures, which are often characterised by turbulent and cyclic flow conditions. In such conditions soil-filter behaviour seems not to be completely described through cohesiortless soil and geotextile properties, as used in many applications of filters in geotechnical engineering (drainage, separation, ctc.). The role of effective stress and hydraulic gradient is here very important, and it must be considered for the correct choice of a geotextile filter. The research here described aims at the study ofthe influence of these parameters on the soil-geotextile interface phenomena. The cyclic flow perpendicular to the filter has been considered among the different possible flow conditions. For a better understanding of these phenomena, a special apparatus has been designed and constructed in order to simulate the on-site behaviour of a representative volume element of filtering interface. The results of tests performed on different soils have shown that, for a given soil-geotextile interface, stability is a function of both effective stress and maximum cyclic hydraulic gradient. The experimental procedure used in these tests has proved to be an efficient performance test for verifying design choices in case of problem soils.

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AUTORI: Tondello M.
Numero di pagine: 18

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