Onur Tastan Coauthored a Paper about Principal Stress Rotation and Intermediate Principal Stress Changes for the Journal of Geotechnical and Geoenvironmental Engineering
Onur Tastan, Ph.D., P.E., M.ASCE (North Carolina) coauthored an article entitled "Effect of Principal Stress Rotation and Intermediate Principal Stress Changes on the Liquefaction Resistance and Undrained Cyclic Response of Ottawa Sand" for publication in the Journal of Geotechnical and Geoenvironmental Engineering on February 22, 2022.
Onur's coauthor was J. Antonio Carraro, Imperial College London.
Onur Tastan is a Principal Engineer based in North Carolina with more than 13 years of experience focused on liquefaction and dynamic behavior of soils, field investigations, dams and dam safety analyses and evaluations, geotechnical fragility analyses, and risk-informed decision making.
The Journal of Geotechnical and Geoenvironmental Engineering covers the broad area of practice known as geotechnical engineering. Papers are welcomed on topics such as foundations, retaining structures, soil dynamics, engineering behavior of soil and rock, site characterization, slope stability, dams, rock engineering, earthquake engineering, environmental geotechnics, geosynthetics, computer modeling, groundwater monitoring and restoration, and coastal and geotechnical ocean engineering.
In laboratory testing, the liquefaction resistance of sands is typically evaluated using cyclic triaxial and simple shear tests. These tests cannot be used in a rigorous manner to systematically assess the effects of principal stress rotation and intermediate principal stress changes on the undrained cyclic response of sands. In this study, the effect of these two factors on the liquefaction resistance of Ottawa sand was investigated using a cyclic hollow cylinder apparatus. At similar initial states of fabric and mean effective stress following K0 consolidation, the liquefaction resistance of Ottawa sand deposited underwater can (1) decrease by 50%–80% as the major principal stress direction moves away from the vertical with σ′2=σ′3, or (2) increase by 200% to 380% as σ′2 increases while σ′1 remains vertical depending on the liquefaction criterion (strain levels). When the stress state defined by the imposed boundary condition deviated from axisymmetric compression, the combined effect on the liquefaction resistance was governed by principal stress rotation.
About the article: Effect of Principal Stress Rotation and Intermediate Principal Stress Changes on the Liquefaction Resistance and Undrained Cyclic Response of Ottawa Sand
About the Journal of Geotechnical and Geoenvironmental Engineering: https://ascelibrary.org/journal/jggefk
Learn more about Onur: https://www.geosyntec.com/people/onur-tastan