The Characterization of the Yield Surface for Fine-Grained Sediments
Hanley, Anthony.
2017
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Abstract: The yield
surface is a contour in stress space that separates a material as behaving elastically
from plastically. The yield surface is fundamental to most mathematical soil models
which are used as the basis for many modern day finite element software packages. Most
model formulations prescribe the yield surface as an elliptical shape symmetrical about
the consolidation axis, however, ... read morethese models are based on very limited data. MIT model
formulations are typically calibrated using three undrained effective stress paths:
normally consolidated undrained compression, normally consolidated undrained extension
and overconsolidated undrained compression. This research adopted the use of the Strain
Energy Method to characterize the shape of the yield surface for Resedimented Gulf of
Mexico Eugene Island (RGoM-EI) and intact Boston Blue Clay (BBC). Specimens were first
K0 consolidated to 1MPa to set the yield surface. They were then unloaded to along a
prescribed K0, OCR path to an OCR of 2. Once unloaded, drained triaxial tests were
carried out to probe in different directions. The strain energy adsorbed by each
specimen travelling along its individual path was plotted and used to characterize the
yield stress. The interpreted yield surface was compared to model formulations; such as
MIT-E3 and MCC. It was found that the yield surface was not elliptical in shape, nor was
it symmetrical about its consolidation axis. The undrained compression stress path
proved to be a good first order approximation of the cap of the yield surface, while the
undrained extension stress path was found to progressively overestimate the yield
surface. MCC and MIT-E3 were found to not accurately predict the yield surface. With the
conclusion that the undrained compression stress path provides a first order
approximation of the cap of the yield surface, it is predicted that the geometry of the
yield surface is stress dependent.
Thesis (M.S.)--Tufts University, 2017.
Submitted to the Dept. of Civil Engineering.
Advisors: John Germaine, and Laurie Baise.
Committee: Lucy Jen, Luis Dorfmann, and Laurie Baise.
Keyword: Civil engineering.read less - ID:
- 1n79hg70g
- Component ID:
- tufts:23097
- To Cite:
- TARC Citation Guide EndNote