Pourya Kargar Coauthors Article on Liquefaction in Soils Dominated by Fines in the Journal Soil Dynamics and Earthquake Engineering
Pourya Kargar, PhD, PE, (Missouri) coauthored “Liquefaction behavior evaluation of a multilayered site with fines-dominated soils” in the June 2023 issue of Soil Dynamics and Earthquake Engineering.
Pourya’s coauthors were Abdolreza Osouli of Southern Illinois University and Sanjeev Kumar of South Dakota State University.
Pourya is a senior staff professional geotechnical and geostructural engineer. His areas of expertise include coal combustion residuals (CCRs), underground structures, dams and levees, retaining structures, soil liquefaction, and foundation design. He routinely conducts 2D and 3D slope stability and seepage analyses, numerical modeling for geotechnical problems, and rock and soil characterization. In addition, he helps clients undertake geotechnical field investigations and ground improvement projects.
Soil Dynamics and Earthquake Engineering is a peer-reviewed journal that supports the field of earthquake engineering by sharing the work of applied mathematicians, engineers, and other scientists whose work addresses earthquake engineering and geotechnical earthquake engineering. The journal is published by ScienceDirect.
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Characterization of liquefaction response in terms of triggering and manifestation at sites with soils containing significant amounts of fines is critically important. Saturated fines-dominated soils, which are susceptible to liquefaction, can have a range extreme responses to earthquake excitations from cyclic mobility to cyclic liquefaction causing excessive displacements. In a multilayered soil profile, the interaction of adjacent layers in porewater pressure redistribution along the site profile plays an important role in liquefaction response. In this study, an advanced Nonlinear Dynamic Analysis (NDA) procedure is shown to predict the liquefaction mechanism and manifestation at a site with multiple fines-dominated soil layers. The procedure simulates the interactions in a multilayered system containing both sand-like and clay-like materials. The liquefaction data recorded by Wildlife Liquefaction Array (WLA) in 1987 Superstition Hills Earthquake (M = 6.6) was deployed to validate the NDA procedure. The WLA site, which consists of sandy silt, silty sand, clayey silt, silty clay, and silt deposits in its upper 20 meters, has provided invaluable records of porewater pressure and ground motions. Two critical-state-based constitutive models, PM4Silt and PM4Sand, in a coupled dynamic-fluid finite difference platform were employed. The constitutive models were calibrated using Cyclic Direct Simple Shear (DSS) test single-element modeling. The simulated response of the site from the proposed approach was compared with those of other NDA procedures conducted on this case history in terms of liquefaction parameters such as excess porewater pressure ratio and maximum shear strain. These comparisons revealed that incorporating multilayer effects in an advanced NDA procedure can enhance the liquefaction behavior predictions at sites with fines-dominated materials.
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