The current filter criteria do not cover the case of fissured clayey soils. To bridge this gap, an attempt has been made to adapt to geotextiles, the No Erosion Filter (NEF) test, developed by Sherard and Dunnigan (1989) for the selection of granular filters. In this test, a clay sample with a 1 trun preforrned hole is placed upstream of a filter and it is submitted to high gradients. The compatibility is assessed from the change in diameter of t}w hole. Nonwoven geotextiles, stacked in one to four layers, were tested against a clay compacted at different .. water contents. The results show that the geotextiles did not fulfill the original NEF criterion and this discrepancy can be attributed to the difference in structure between granular and geosynthetic filters at the very interface. How ver, most of the tests have ended with clear water outflows. This could leaq to a relaxation of the original NEF acceptability level when geotextiles are involved.
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