The potential of a novel, bio-mediated soil improvement to increase resistance to liquefaction triggering and to reduce the consequences of liquefaction if it occurs was evaluated. Microbial induced calcite precipitation (MICP) binds sand particles together through calcite crystal formation at particle-particle contacts. This results in an increase in the small-strain stiffness and strength of treated loose sand. Geotechnical centrifuge tests were used to evaluate the increased resistance of MICP treated sand relative to untreated loose sand when subjected to seismic shaking. Results of one model with a structure founded on sand treated to a moderate level of cementation and another model with the structure founded on loose untreated sand are compared. The centrifuge models were subjected to ground motions consisting of sine waves with increasing amplitudes. The accelerations, pore pressures, and shear wave velocities measured in the soil during shaking are presented. The resistance to liquefaction and deformation in the MICP treated model showed significant increases, as evidenced by substantial decreases in excess pore pressure ratios and vertical strains beneath the structure.
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