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Louisiana State University

Theses/Dissertations

2004

Granular materials

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Development Of Resilient Modulus Prediction Models For Base And Subgrade Pavement Layers From In Situ Devices Test Results, Ravindra Gudishala Jan 2004

Development Of Resilient Modulus Prediction Models For Base And Subgrade Pavement Layers From In Situ Devices Test Results, Ravindra Gudishala

LSU Master's Theses

Currently, the design of flexible pavements is generally conducted based on static properties such as California Bearing Ratio and soil support value. These properties do not represent the actual response of the pavement layers under traffic loadings. Recognizing this deficiency, the current and the 2002 mechanistic –empirical guide for design of pavement structures recommended the use of resilient modulus for characterizing the base and subgrade soil and for the design of flexible pavements. The objective of this study was to develop models to estimate the resilient modulus of base and subgrade soils from in situ test devices. Two types of …


Assessment Of Shearing Phenomenon And Porosity Of Porous Media Using Microfocus Computed Tomography, Bashar Adeeb Alramahi Jan 2004

Assessment Of Shearing Phenomenon And Porosity Of Porous Media Using Microfocus Computed Tomography, Bashar Adeeb Alramahi

LSU Master's Theses

Microfocus x-ray computed tomography (μCT) is a powerful non-destructive scanning technique to study the internal fabric of granular materials. In this thesis, μCT was applied to two cases. The first case involves studying the behavior of particles in a triaxial specimen during shearing. Three-dimensional translation and rotation of the particles were tracked throughout the shearing process, and they were used to calculate the local strain distributions. Moreover, the local dilatancy angle distribution was calculated throughout experiment. These distributions were compared to study the changes in the behavior of the particles at different stages of the test. It was noticed that …


Numerical Modeling Of Strain Localization In Granular Materials Using Cosserat Theory Enhanced With Microfabric Properties, Mustafa Alsaleh Jan 2004

Numerical Modeling Of Strain Localization In Granular Materials Using Cosserat Theory Enhanced With Microfabric Properties, Mustafa Alsaleh

LSU Doctoral Dissertations

Finite element solution in the updated Lagrangian frame is used to investigate the strain localization phenomenon "shear bands" in granular materials. The micro-polar theory was used as the mathematical foundation for the continuum formulations. A laboratory testing results are used for verification and comparison with the numerical simulation. Silica sand and glass beads with different shape indices, size and surface roughness were tested under biaxial and triaxial loading conditions to investigate the physics of the problem. The shape non-uniformity and the irregular surface roughness of the grains were studied carefully to evaluate their effect on shear band characteristics. To this …