Constitutive Modeling Including Creep- and Rate-Dependent Behavior and Testing of Glacial Tills for Prediction of Motion of Glaciers
Publication: International Journal of Geomechanics
Volume 11, Issue 6
Abstract
The disturbed state concept (DSC) is used to characterize the deformation behavior of glacial tills, which may have a significant role in the motion of overlying glaciers with attendant implications for global climate dynamics. The model includes elastic, plastic, and creep deformation; microstructural modifications leading to softening and failure; and effect of rate of loading. This paper also presents a procedure to construct the static yield surface, which is essential to model the full creep response of the material. Laboratory triaxial tests are performed to calibrate the model. Predictions are compared with the test data, which include independent validations. A finite-element (FE) program with the implementation of the DSC model is used to predict the motion of an idealized ice sheet as affected by the deformation in the till. A novel concept is proposed to predict the failure and resulting motion of ice sheets. The concept involves the definition of state in the deforming till when stress, strain, and the disturbance reach critical values beyond the peak stress. The proposed concept is considered to be more realistic than the commonly used Mohr-Coulomb (M-C) criterion, in which failure and motion are assumed to occur at the peak stress with very small (elastic) strains.
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Acknowledgments
Partial funding for the project was provided by the National Science Foundation award No. NSFEAR-0229889 to the University of Arizona. The research for the DSC/HISS model was also supported by various grants from the National Science Foundation in Washington, D.C. A number of students and colleagues (cited in references) participated in the development and use of the DSC/HISS model for a wide range of materials and interfaces/joints. The participation and assistance of D. N. Contractor, A. Carlson, Peter Clark, and A. Pandey are gratefully acknowledged.
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Published In
International Journal of Geomechanics
Volume 11 • Issue 6 • December 2011
Pages: 465 - 476
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Sep 11, 2009
Accepted: Sep 21, 2010
Published online: Sep 23, 2010
Published in print: Dec 1, 2011
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