The Terzaghi Lecture: Criteria for geotextile and granular filters

Presenter: Dr J P Giroud

Venue: Institution of Civil Engineers, London

A summary of more than 30 years of work on geotextile and granular filters by the author. A rational approach to the development of filter criteria is presented in a lively manner using animated slides. In particular, the author demonstrates that, while two criteria are needed for granular filters, four criteria are needed for geotextile filters. The author also demonstrates that, while the traditional permeability criterion for granular filters is adequate, the retention criterion for granular filters could and should be improved by adapting some of the features of the retention criterion for geotextile filters. The application of the filter criteria is illustrated and discussed step by step using the case history of the design, construction and performance monitoring of a geotextile filter in a dam constructed in 1970 and still in service.