Physical modelling of backward erosion piping in foundation beneath levee

Koito, N. and Horikoshi, K. and Takahashi, A. (2016) Physical modelling of backward erosion piping in foundation beneath levee. In: ICSE 2016 (8th International Conference on Scour and Erosion), 12-15 September 2016, Oxford, UK.

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Abstract

Centrifuge model tests are performed to observe piping progression in foundation beneath levee and to examine influence of repeated seepage and thickness of foundation ground on piping progression. Once the pipe is formed beneath the levee, hydraulic gradient upstream of the pipe tip becomes larger while that along the pipe becomes rather small. Shift of this large hydraulic gradient position to the upstream with rise of the flood water level leads to the large subsidence of the slope in the protected side and marked increase in flow rate. Repeated seepage and thickness of the permeable foundation layer have influence on stability of levee against piping. Repeated seepage makes the piping progression faster and levee vulnerable to the piping formation. With the thinner permeable foundation layer beneath the levee, the levee is at higher risk to cause brittle failure while the required hydraulic gradient to cause piping is larger.

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