Soomin Ham

Postdoctoral Researcher

University of California, Davis

Soo-Min Ham currently works as a postdoctoral researcher in Department of Civil and Environmental Engineering at University of California Davis, Davis, United States. She received her BSc (2014) followed by MS (2016) and PhD (2021) at Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. During her PhD, she worked for 8 months as a visiting scholar at Washington State University to do research on the soil erosion behavior. She has extensive experience in (1) energy geomechanics and geotechnology; (2) sustainable bioinspired geotechnical engineering; and (3) advanced numerical modeling. Results from her research have been published in 8 archival journal papers. Her contributions have been recognized through the Korea Federation of Women's Science and Technology Associations (2022) and Korean Geotechnical Society (2015, 2016, 2021).

Soil improvement technique by microbial induced calcite precipitation

Microbial induced calcite precipitation (MICP) has recently gained attention as an environmentfriendly ground improvement method. The produced calcite (calcium carbonate) minerals act as a cementation agent and improve the engineering properties while its extent of improvement depends on the amount of calcium carbonate precipitated. They modify the soil properties through cementing at particle contacts, coating of particles to increase a density, and roughening of surfaces to increase a dilatancy. This research (a) illustrates the grain-scale cementation characteristics by MICP, (b) suggests the bonding model parameters for discrete element method modeling of cementation by MICP, (c) examines the improvement in erosion resistance of sands by MICP, and (d) investigates the effect of MICP on liquefaction mitigation. The calcium carbonate deposition mode, tensile and shear strengths of MICP-treated beads, and failure modes were discussed for grain-scale characteristics. Based on the obtained cementation strength and the grain-scale mineral precipitation pattern, a guideline for selecting the bonding parameter values was suggested. The effect of the MICP treatment on the surface erosion behavior of sand was investigated with the erosion function apparatus test. Increased resistances of MICP-treated sand when subjected to seismic shakings were shown by the results of the geotechnical centrifuge tests. The results provide the experiment data from the micro-scale to the system-scale for developing the mechanical behavior model of MICP-treated sand and for suggesting the input parameter values to describe the bonding model.