Piping erosion mechanisms of organic soil and bioabatement of piping erosion of sand

This thesis presents the findings of a preliminary research program aimed at investigating the mechanisms governing the progression of piping erosion in organic soils. The hypothesis is that the presence of organics within mineral soils results in a reduction in piping erosion progression. Erosion behaviors of the soils are quantified using the hole erosion test (HET), and the research is split into five test phases. In Phase 1, the influence of grain size distribution is eliminated in order to develop a preliminary understanding of the role that organic matter plays in the erosion process. Results indicate that organic matter likely contributes to a reduction in piping erosion progression. The second phase excludes both grain size distribution and individual particle shape as variables in the erosion process. Results further confirm the connection between organic matter content and erosion resistance. The third phase reveals the positive correlation between increased organic matter content and reduction in piping erosion progression. The fourth phase investigates certain biologically derived substances that have been shown to effectively bind individual particles into larger, more stable aggregates. Positive correlations indicate that these substances likely play a major role in reducing piping erosion progression. The final phase suggests that the introduction of organic material into mineral soil decreases shear strength, increases consolidation settlement, and reduces permeability.