2023 Geo-Mat Graduate Seminar
Dr. Dong-Hwa Noh
University of Nebraska-Lincoln
Effect of Soft Viscoelastic Biopolymer on Undrained Shear Behavior of Contractive Sand
March 10th, 2023
09:00 AM
Lincoln and Omaha
PKI 160
NHW213
Abstract:
Saturated loose sands are prone to contractive failures associated with excess pore pressure generated by undrained loading. Recently, use of soft viscoelastic biological products, such as biopolymers and biofilms, has garnered significant interest as an alternative bio-grout material for ground improvement because of their non-toxic and biodegradable characteristics. However, the impact of soft viscoelastic inclusions, such as gel-like biopolymers, on undrained responses of treated soils remains poorly understood. This study explores the undrained load-deformation behavior of contractive sands treated with a soft viscoelastic biopolymer, gelatin. A series of the consolidated-undrained (CU) compression tests are conducted using loose and contractive sands treated with gelatin to obtain stress-strain responses and monitor variations in S-wave velocity (VS) during undrained loading. The results of stress-strain curves, VS variations, and effective stress paths reveal that the inclusion of a viscoelastic biopolymer restrains the contractive behavior associated with post-peak softening but increases the undrained shear strength of contractive loose sands. This effect becomes more distinct, and the undrained strength increases further as the biopolymer stiffness increases. In addition, the loading history (or consolidation-gelation sequence) has a pronounced effect on the undrained shear strength, which has significant implications on field implementation strategies. This study presents a unique experimental dataset on the undrained responses of soft viscoelastic biopolymer-treated sands and also provides insight into the feasibility of using biopolymers to improve the undrained strength of loose contractive sands that are prone to liquefaction.
Bio:
Dr. Dong-Hwa Noh currently works as a postdoctoral research fellow in the Department of Civil and Environmental Engineering at the University of Nebraska-Lincoln. He received his BSc from Pusan National University and his MS and Ph.D. from the Korea Advanced Institute of Science and Technology (KAIST). During his Ph.D. studies, he spent six months working as a visiting scholar in the Physical Science and Engineering Division at King Abdullah University of Science and Technology (KAUST). His main research interest is in understanding the geophysical, hydraulic, and mechanical responses of bio-inspired soils, including: (1) the effect of biopolymers on the load-deformation behavior of contractive sands, (2) the effect of soft or hard inclusions on seismic wave responses of porous media, and (3) permeability control using microbial activities. He is recently active in two research projects related to the study of microfiber-reinforced engineered barrier materials for nuclear spent fuel storage and injection strategies for convection-enhanced drug delivery.