Statistical study of no-erosion filter (NEF) test results

Filter design criteria predicated on no-erosion filter (NEF) test results are widely adopted for filter substantiation in earth dams. Hitherto, repetitions of NEF tests on various base-soil-filter combinations have suggested some anomalies between test results and accepted filter criteria. This treatment analyses a large database of NEF tests available in the literature, and carefully assesses the influences of different base-soil properties, including d85, fines content, clay content, plasticity index and sand content on the experimentally defined boundary filter (i.e. D15b). The parametric study presented, alongside the available criteria, may improve the design of optimum - that is, safe and economical - filters.