Incorporating the Influence of Microbially Induced Carbonate Precipitation in Nonlinear Site Response Analyses

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4. Incorporating the Influence of Microbially Induced Carbonate Precipitation in Nonlinear Site Response Analyses

Microbially induced carbonate precipitation (MICP) is a natural biological process that can be harnessed to improve soil behavior. One promising application of MICP is for liquefaction mitigation due to its enhancement of shear strength and dilative tendencies in sands even at light levels of cementation. However, if MICP is used in seismically active regions, the dynamic response of the cemented material must be considered in elucidating the soil-infrastructure system performance. The strain-dependent dynamic response of the MICP-cemented materials can be characterized using modulus reduction and material damping (MRD) curves. Our findings show that empirical MRD curves of MICP-cemented sands experience an evolution in shear modulus and shear strain thresholds as a function of the level of MICP-cementation, which can be captured through a predictive formulation sensitive to the level of cementation and confining pressure. One-dimensional nonlinear site response analyses can incorporate relevant MRD curves to understand the influence of cementation level and its vertical extent on the characteristics of ground motions. This is important to advance our understanding of potential changes in the seismic demands on civil infrastructure systems supported on improved ground via MICP. The results can be used to illuminate appropriate cementation levels to minimize amplification of ground motions while reducing excess pore water pressure generation, as well as to highlight further needs in developing MICP-specific MRD curves.

2025 International Conference on Bio-mediated and Bio-inspired Geotechnics (ICBBG2025)

General session: Bio-mediated methods for hazard mitigation