PIPING PHENOMENON AT THE FLOOD CONTROL DIKES IN THE CARPATHIAN-BASIN (II)
L. Nagy
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