ABSTRACTS. - Piping phenomenon at the flood control dikes in the carpathian-basin. Pipings are the most spectacular phenomena preceding and ultimately leading to breach of flood protection dikes. The piping is close correlation with the geological history of the flood plane. A review of historic data showed that 1 in every 12 to 13 dike failures was the consequence of piping (Nagy, 2002). This paper places particular emphasis on a special feature in the protection against piping directing attention to some important aspects of flood defence and to the need for going into a deeper study of certain details of the phenomenon of piping. Undoubtedly, we know a great deal more about piping than we did just 30 years ago. Research has been pursued in various fields in an attempt to find answers to some peculiar but very real problems, as grading entropy shed light on soils prone to piping from the theoretical side (Lőrincz 1986, 1993, Lőrincz et al., 2004, Imre et al., 2008), but the practical approach revealed that in the vicinity of all the pipings a particular layer prone to piping failure invariably occurred in the stratified soil (Lőrincz, Nagy 1995, 2010). In the case of recorded actual pipings the mean hydraulic gradient only reached a value that was as low as less than one fifth of the allowable value, yet failure conditions did occur (Nagy et al., 1994).
Key words: flood defense, hydraulic failure of dikes, rapid sand boiling/piping, piping sand