Synthetic Fabrics as Soil Filters: A Review

The fundamentals of fabric filters, their uses, design, longevity, strength requirements, and testing are reviewed and discussed. For unidirectional laminar flow conditions, particle retention and permeability criteria for fabric filters are well established. All the approaches currently adopted tend to give similar answers and are dependent on the fabric being the ‘catalyst’ in the formation of a ‘self-induced’ filter within the retained soil. When problems occur in practice, it is normally due to clogging of the filter, i.e. the fabric is too fine. Thin fabrics appear most suited for this use. For severe hydrodonamic and reversing flow conditions, the self-induced’ filler will not form, and design criteria are not so well established or accepted. Thicker fabrics offer a more tortuous path to the migration of particles and are thus more suited than thin fabrics. However, thin fabrics have successfully been used in conjunction with (out of specification) granular filters.