Mixing Nanoclay Additive to Improve Internal Erosion Resistance of Earth Dams Constructed of Silty Sand

Seepage-induced erosion is one of the main reasons leading to the catastrophic failure of earth dams, levees, and dykes. Mitigation measures include grouting or mixing additives with the soil. In the present study, nanoclay (NC) was investigated as an additive for silty sand soil, considering 1 and 1.5 wt.% NC additions, employing curing periods of 1, 7, 14, and 28-days for the soil–NC mixtures. Homogeneous model dams were then prepared by compaction of the unamended and cured -amended soil materials to the same cross-sectional profile in a laboratory flume apparatus. Once the upstream water level had reached the required water depth, the internal erosion process was initiated by opening a 6-mm dia. preformed hole created through the base width of the model dams next to the flume’s glass sidewall panel. To track the entire erosion process, side-view video recordings of the eroding dam cross-section were taken, employing a novel digital image-processing technique (previously developed by the authors) to track the progression of piping that ultimately lead to breach failure occurring. Original experimental results presented herein show the positive effect of the NC addition on erodibility reduction. From the NC content and curing ranges examined, the 1 wt.% NC and minimum 7-day curing period combination were tentatively identified as producing the best improvement in internal erosion resistance for the investigated soil.