Thesis (M.S.)--Missouri University of Science and Technology, 2008. / Vita. The print version of this thesis includes an accompanying CD-ROM. "Included with this Thesis is a CD-ROM, which contain the VISUAL BASIC CODE for the S4 application...The included code is divided into three files: a) VISUAL BASIC Module Code, b) VISUAL BASIC Form Code, and c) VISUAL BASIC FFT Code."--leaf 158. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 25, 2008) Includes bibliographical references (p. 160-172).

Thesis (M.E.)--University of Canterbury, 2007. / Typescript (photocopy). "August 2007." Includes bibliographical references (leaves 142-145). Also available via the World Wide Web.

Thesis (Ph. D.)--Carleton University, 2001. / Includes bibliographical references (p. 193-208). Also available in electronic format on the Internet.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 69-74).

Thesis (Ph. D.)--University of California, Davis, 1998. / Cover title. "September 1998." Includes bibliographical references.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "December 2008." Includes bibliographical references (leaves 87-89). Online version available on the World Wide Web.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 2001. / "April 6, 2001." UMI order no. 3030350 Includes bibliographical references.

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

Ces travaux portent sur l’étude de l’influence du degré de saturation sur le comportement instable du sable de Fontainebleau sous sollicitations cycliques, et particulièrement vis-à-vis des risques de liquéfaction. Il s’agit d’évaluer expérimentalement le potentiel de liquéfaction d’un matériau granulaire en fonction de son degré de saturation initial. Pour cela, un cadre théorique est proposé, définissant trois zones d’états de saturation : une zone totalement saturée, dont le fluide poral est uniquement de l’eau ; une zone quasi-saturée, dont le fluide poral est constitué d’eau et d’air dissout ou occlus, et pour laquelle les effets de la succion sont négligés ; et une zone non saturée, caractérisée par une phase gazeuse continue, et des valeurs de succion positives. Les frontières du cadre théorique sont déterminées en termes de degrés de saturation. Chaque zone est ensuite investiguée expérimentalement. Une série d’essais triaxiaux cycliques est réalisée. Pour chaque essai, les conditions initiales de saturation sont fixées, et correspondent aux conditions de saturation déterminées dans le cadre théorique. Pour la zone non saturée, un équipement spécial de plaque tensiométrique est développé et mis en place au laboratoire afin d’imposer des conditions de succion initiales précises aux échantillons. Pour la zone quasi-saturée, les conditions de saturation initiale sont imposées via une courbe de calibration reliant le coefficient de Skempton B au degré de saturation, préalablement réalisée au laboratoire. Les résultats mettent en évidence que le sable de Fontainebleau liquéfie même lorsque le degré de saturation initial est inférieur à 100%. Plus particulièrement, tous les échantillons de la zone quasi-saturée montrent un état de liquéfaction totale à la fin du chargement cyclique. Les échantillons de la zone non saturée quant à eux ne montrent aucun signe de comportement instable sous l’action du chargement cyclique, pour les mêmes conditions de densité et de contrainte. Il semble donc que le schéma de répartition du fluide interstitiel joue un rôle fondamental dans le potentiel de liquéfaction d’un sable ; dans les conditions de densité et de contraintes testées ici, la phase gazeuse continue, et les valeurs de succion initiale positives permettent de préserver le matériau vis-à-vis du risque de liquéfaction. Au contraire, si la présence d’air sous forme dissout ou occlus permet de retarder le déclenchement des instabilités au sein du matériau granulaire, elle n’empêche pas la liquéfaction. / This work aims to study influence of saturation degree on unstable behavior under cyclic loading, and more specifically against risks of liquefaction. The potential of liquefaction of Fontainebleau sand is evaluated experimentally, in function of its initial degree of saturation. A theoretical frame is established, defining three areas of saturation states: a fully saturated zone, where pore fluid consists only of water; a nearly-saturated zone, where pore fluid consists of water and dissolved or occluded air, and where effects of suction are neglected; an unsaturated zone, where gaseous phase is considered as continuous, and suction is positive. Boundaries of this theoretical frame are defined in terms of saturation degree. Each zone is then experimentally investigated. Cyclic triaxial tests are performed. For each test, initial conditions of saturation are imposed, in agreement with saturation conditions parameters defined in the theoretical frame. For unsaturated zone investigation, a special equipment of Negative Water Column is developed and used in the laboratory in order to obtain initial conditions of suction in the sample. For nearly-saturated zone investigation, initial conditions of saturation are imposed through a calibration curve, linking Skempton coefficient B and saturation degree, previously obtained in the laboratory. Results show that Fontainebleau sand liquefies under cyclic loading, even when initial saturation degree is below 100%. More specifically, every sample tested on the nearly-saturated zone are in a complete state of liquefaction after cyclic loading is applied. Samples on the unsaturated zone did not show any sign of instability, under same conditions of stress applied and density. It seems that distribution pattern of pore fluids within granular material plays a major role regarding potential of liquefaction. In state of stress and density tested in this study, continuous air phase and positive suction prevent granular material from liquefaction. On the contrary, if dissolved or occluded air as a pore fluid delays the onset of instabilities and liquefaction, it does not prevent it.

The liquefaction resistance of a saturated medium sand with varying amount of non-plastic type F fly ash was evaluated by conducting cyclic triaxial tests. The test results were used to evaluate the effect of addition of various percentages of fly ash on the liquefaction resistance of Ottawa sand. The effect of cyclic shear stress and confining pressure on liquefaction resistance of the sand-fly ash mixtures was the main scope of this research. In addition, the Young's Modulus and Damping Ratio for sand-fly ash mixtures were also determined. A comprehensive experimental program was conducted in which 50 stress controlled cyclic triaxial tests were performed on a clean sand, sand containing 25%, 30%, 50% and 70% fly ash at a constant relative density of 50%. The results show that sand containing 25% fly ash has the highest liquefaction resistance under cyclic loading in comparison to clean sand and sand containing 30%, 50% and 70% fly ash. The cyclic resistance goes on decreasing as the fly ash content further increases. The test result also shows that the liquefaction resistance of the clean sand and sand containing 70% fly ii ash is almost same. The test results were also examined in terms of the conceptual framework of Thevanayagam (2000). The effects on liquefaction resistance were also measured in terms of pore water pressure generation and deformation of the sample. As the confining pressure increases, shear stress required to cause initial liquefaction of the sample also increases. Modulus of Elasticity was seen to increase with increase in confining pressure and decrease with increase in axial strain for all cases of sand-fly ash mixtures used in these tests. The damping ratio of the sample increases with the increase in axial strain upto about 1% and then it either decreases or remains constant thereafter. There was no clear correlation of damping ratio with confining pressure.