FILTRATION PROPERTIES OF GEOTEXTILE AND MINERAL FILTERS RELATED TO RIVER AND CANAL BANK PROTECTION

Abstract Filter applications in earthworks, foundation engineering and hydraulic structures nowadays use mineral and textile filters as competitive filter media. At first sight these filter media seem to be different, but a fundamental comparison demonstrates similarities in operation and design criteria. Special attention is given to the soil-retention ability and therefore to the safety of filter operation, which is mainly influenced by the relative filter thickness (filtration length). River and canal banks erode in different ways due to various causes. The nature of the in-situ soil and the loads imposed by waves and currents are the most important factors. The types and causes of failures of revetments are described and development from the initial use of single layer woven fabrics to the current recommendations of the Federal Institute for Waterways Engineering (BAW), Karlsruhe, which involve the use of heavy multi-layer fabrics is traced.