Abstract
A plasticity model for representing clays and plastic silts in geotechnical earthquake engineering applications will be described and its calibration using in-situ or laboratory test data will be illustrated with examples. The PM4Silt model (Boulanger and Ziotopoulou 2018) builds on the framework of the stress-ratio controlled, critical state based, bounding surface plasticity PM4Sand model. Modifications to the model were developed and implemented to improve its ability to approximate undrained monotonic and cyclic loading responses of low-plasticity silts and clays, as opposed to those for purely non-plastic silts or sands. Emphasis was given to obtaining reasonable approximations of undrained monotonic shear strengths, undrained cyclic shear strengths, shear modulus reduction and hysteretic damping responses across a range of initial static shear stress and overburden stress conditions. The model is coded as a user defined material in a dynamic link library (DLL) for use with the program FLAC 8.0 (Itasca 2016). Calibration of the model will be illustrated with examples involving soft, low-plasticity silts and clays with plasticity indices ranging from 4 to 20 and representing a range of monotonic and cyclic undrained loading behaviors. The performance and limitations of the PM4Silt model for earthquake engineering applications will be discussed.
About the speaker
Prof. Ross W. Boulanger received his PhD in Civil Engineering from the University of California, Berkeley in 1990. He joined the University of California, Davis in 1992 and is currently the Professor of Civil and Environmental Engineering and the Director of Center for Geotechnical Modeling.
Prof. Boulanger’s research interests focus on geotechnical earthquake engineering with emphases on liquefaction and its remediation, seismic performance of earth dams and levees, and seismic soil-pile-structure interaction.
Prof. Boulanger was elected a Member of the US National Academy of Engineering (2017) and a Fellow of the American Society of Civil Engineers (2012). He received numerous awards including the Ralph B. Peck Award by the American Society of Civil Engineers (2016), the T. K. Hsieh Award by the Institution of Civil Engineers (2014), the Norman Medal (2006) and the Walter L. Huber Civil Engineering Research Prize (2002), both were awarded by the American Society of Civil Engineers.
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