Multiphase Biogeochemical Model to Predict Microbially Induced Desaturation and Precipitation at Field-Scale

Microbially induced desaturation and precipitation (MIDP) via denitrification is emerging as a sustainable alternative ground improvement technique to address geologic hazards. Currently, we are investigating the potential of applying MIDP to mitigate earthquake-induced liquefaction of sandy soils. MIDP influences the geochemical environment and the hydro-mechanical behavior of soils through precipitation of calcium carbonate, biogenic gas production, and biomass growth. Calcium carbonate has the potential to improve soil strength, whereas biogenic gas can reduce pore pressure build-up during cyclic loading. The products of MIDP have shown potential to mitigate liquefaction at the lab-scale, but up to now, field-scale application has been limited. We have developed a multiphase biogeochemical reactive transport model to predict the distribution of substrates and products and their effects on the hydro-mechanical properties. Subsequently, these results have been used to optimize treatment deployment procedures based on local site characteristics, including subsurface heterogeneity. Field-scale observations will be used to validate the model, such that this model can be used as a tool for future MIDP implementation in various geologic and environmental conditions.