Revetment damage as a result of geotextile colmation by flocculated ochreous products and possible repair methods

摘要

During the last years some severe local damage to bank revetments incorporating a geotextile have occurred, for which the reason has been a severe reduction of the hydraulic performance of the nonwoven filter layer as a result of accumulation and incorporation of ochreous products flocculated from the groundwater. This report describes the conditions of a specific application case leading to this type of failure and gives some criteria for repair methods. Two filter variants had been designed for this purpose, based on a very open nonwoven-woven composite and on a coarse mineral filter. Due to a heavy seepage-water exit the geotextile was impossible to be installed. Thus only a pilot repair project could be carried out by using the mineral filter. A report on its behaviour is given based on an observation time of about 9 years.