Application of bio-cement in erosion control of levees

To mitigate the erosion problem due to overtopping, the MICP (microbial induced carbonate precipitation) treatment method was applied to the levee surface so that its resistance to erosion was improved. By spraying the bacterial cells and nutrient solutions into the surface sand of levee, the gelation of calcium carbonate can precipitate rapidly in the interspaces, improving the mechanical properties of levee surface sand. To this end, the spray method was first used to treat the surface layer of levee model, and then the flume test was carried out to evaluate the ability of the model against erosion. After the flumes test, the engineering properties of the soil in the model were examined using an unconfined compressive test and hydraulic conductivity test. The experimental results show that the engineering properties of the model soil has been greatly improved. The UCS (unconfined compressive strength) reaches up to 9 MPa. The hydraulic conductivity of the bio-treated sand taken from the levee model is reduced from the initial value of 4.0x10(-4) to 7.2x10(-7) m/s. In short, the bio-grouting technology has a potential to be used in practice with a broad application prospect in erosion control of levees.