Microbially Induced Calcite Precipitation (MICP) to mitigate contact erosion in earth embankment dams and levees

Abstract

Internal erosion of water retaining structures (such as earth embankment dams, levees and dykes) is a major geotechnical problem. Contact erosion is a specific type of internal erosion that occurs at the interface between fine and coarse soils, for instance along the downstream edge of the core-filter interface, and can lead to earth dam failure due to internal erosion. Although in new dams this may be avoided by fulfilling the filter criteria or with the construction of barriers, retrofitting older structures often entails significant design and construction costs due to the uncertainties surrounding their materials and behaviour. In this context, microbially induced calcite precipitation (MICP), a bacteria-induced bio-mineralisation process capable of binding soil particles in situ, provides a cost-effective alternative for contact erosion control. However, it is necessary to establish a solid understanding of how biogenic cementation occurs at the interface between fine and coarse sands and its influence on the erosion and hydro-mechanical characteristics.