Case Study on Failure Mechanism of Flood Embankments Due to Rapid Sand Boiling on Alluvial Flood Plains and the Identification of Vulnerable Levee Sections

Hungary is situated in the deepest part of the Carpathian basin. The majority of the country is alluvial plain. Rivers crossing these plains filled the basin with their sediments and meandered on the deposited sediment during the geological ages. Thus the continuous levee systems developed in the second half of the 19th century, replacing the earlier, rather local defenses, intersected at a number of locations the unforgotten and invisible ancient riverbeds. Experience showed that as the height of the levees was raised to follow the rising tendency of the flood crests, the number of failures due to foundation stability loss started increasing. Fighting against piping (sand boiling) became a major issue. Professionals observed that in many cases there was no time to interfere against rapidly developing sandboilings which led to the collapse of the levee section. A research program discovered the reasons and conditions of these phenomena and gave solutions and tools to recognize the problematic sections in advance