viagra cialis

Last Update: 2010-12-10

Download

GeotechLinks documents are from different resources in the internet and we just try to put them together in related categories. Before downloading the requested document remember that:

1-It is up to you to ensure that your use of a document does not infringe copyright law.
2-GeotechLinks is not responsible for the correctness of the contents of the documents.

GL2251-
2006, Navarantnarajah Sasiharan, PhD thesis, Washington State University, Department of Civil and Environmental Engineering

Abstract:

A novel conceptual model of the mechanics of sands is developed within an elastic-plastic framework. Central to this model is the realization that volume changes in anisotropic granular materials occur as a result of two fundamentally different mechanisms. The first is purely kinematic, dilative, and is the result of the changes in anisotropic fabric. There is also a second volume change in granular media that occurs as a direct response to changes in stress as in a standard elastic-plastic continuum. Inclusion of the two sources of volume change into the modified Cam Clay dissipation function results in a new anisotropic model which is suitable for sands with pronounced anisotropic granular arrangement. The conditions that lead to features such as phase transition line and ultimate state line that dense sands exhibit are predicted theoretically by the new anisotropic sand model and confirmed with experimental results. The conventional volumetric-shear strain relation obtained from triaxial experiment is used to determine the evolution of fabric anisotropic parameter. The new anisotropic sand model is generalized to 3-D cases. Bounding surface plasticity theory is used to capture plastic deformation at small strain levels as well as during unloading/reloading. This enables the robust modeling of the accumulation of plastic strains as well as the buildup of excess pore pressure under cyclic loading of sands. The bounding surface formulation is implemented to the numerical code FLAC3D and used to simulate drained and undrained triaxial tests on Ottawa sand. The FLAC3D model is also used to simulate undrained cyclic triaxial test and predict the liquefaction behavior of Nevada sand observed in centrifuge tests. The analysis shows that the stress induced volumetric strain is the main cause for pore pressure build up leading to initialization of liquefaction whilst the fabric induced volumetric strain influences the post liquefaction behavior of sands.

Already one of 2794 GeotechLinks members? Sign up here to receive updates and news.

Copyright © 2006 Siavash Ghabezloo. All rights reserved.