Journal Published Online: 21 June 2021
Volume 44, Issue 6

Erosion in Low to High Plasticity Silts and Clays due to Floodwall Overtopping



Floodwall overtopping erodes the levee surface. A better understanding of the erosion rate of levee-floodwall systems is crucial for designing such structures. Scouring induced by overtopping during storm events can cause failure of these geo-structures. In this study, the contributing factors such as floodwall height, soil characteristics, and hydraulic characteristics of overtopped flow are considered to predict erosion rates for such levees built with fine-grained soils. Using over 60 simulated scaled levee-floodwall test results, the effect of the contributing parameters on soil erosion are described and quantified. The tested soils had relatively wide ranges of plasticity index (non-plastic (NP) to 40 %), degree of compaction (70 to 90 %), and degree of saturation (15 to 85 %). Various scales of the floodwalls (1:20 to 1:2) and overtopped flow velocities (FV) (0.2 to 0.6 m/s) were used. The response of soils with high plasticity and low plasticity was different to erosion. Highly plastic soils experienced sloughing and more resistance toward erosion, whereas in low plastic soils scour developed. Also, the erosion rates are more sensitive to plasticity index and floodwall height than degree of compaction or degree of saturation. Using the lab-scaled simulation results, a prediction model was developed to estimate erosion rates. The developed model was used to estimate the erosion rates in three case histories and compared with measured values. The limitations and advantages of the model were analyzed and discussed.

Author Information

Osouli, Abdolreza
Civil Engineering Department, Southern Illinois University Edwardsville, Edwardsville, IL, USA
Nassiri, Sina
Civil Engineering Department, Southern Illinois University Edwardsville, Edwardsville, IL, USA
Pages: 18
Price: $25.00
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Stock #: GTJ20200173
ISSN: 0149-6115
DOI: 10.1520/GTJ20200173