abstract: This research focuses on the stress and structure evolution observed in-situ during the earliest stages of thin film growth in Cu on Au(111)-reconstruction. For the research, an ultra high vacuum-scanning tunneling microscopy (UHV-STM) system was modified to have the additional capabilities of in-situ deposition and in-situ stress evolution monitoring. The design and fabrication processes for the modifications are explained in detail. The deposition source enabled imaging during the deposition of Cu thin films, while also being columnar enough to avoid negatively impacting the function of the microscope. It was found that the stress-induced changes in piezo voltage occurred over a substantially longer time scale and larger piezo scale than used during imaging, allowing for the deconvolution of the two sources of piezo voltage change. The intrinsic stress evolution observed at the onset of Cu growth was tensile in character and reached a maximum of 0.19 N/m at approximately 0.8ML, with an average tensile slope of 1.0GPa. As the film thickness increased beyond 0.8 ML, the stress became less tensile as the observation of disordered stripe and trigon patterns of misfit dislocations began to appear. The transport of atoms from the surface of enlarged Cu islands into the strained layer played an important role in this stage, because they effectively reduce the activation barrier for the formation of the observed surface structures. A rich array of structures were observed in the work presented here including stripe, disordered stripe and trigon patterns co-existing in a single Cu layer. Heteroepitaxial systems in existing literature showed a uniform structure in the single layer. The non-uniform structures in the single layer of this work may be attributed to the room temperature Cu growth, which can kinetically limit uniform pattern formation. The development of the UHV-STM system with additional capabilities for this work is expected to contribute to research for the stress and structure relationships of many other heteroepitaxial systems. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2012

A case study is considered in which data produced by different techniques have been gathered in various locations within a rock mass in which topography effects are most likely significant. Measurements were performed for the design of a re-powering scheme that includes a new hydraulic conduit and an underground cavern that will primarily be excavated in granite. An integrated approach for extrapolating the results from the various in situ tests to the rock mass volume of interest for the hydroelectric power scheme is presented. This approach includes the development of an equivalent continuum mechanics model. The integration of in situ tests and numerical modelling enables to determine the stress spatial variation which helps ascertain the loading mechanism at the origin of the measured stress field as well as the long-term rheological behavior of the equivalent geomaterial under consideration.

Considérons un cas d’étude dans lequel les données produites par différentes techniques ont été obtenues en divers points d’une masse rocheuse où les effets topographiques sont très probablement significatifs. Les mesures ont été effectuées pour la conception du réseau hydroélectrique. Le réseau comprend une conduite hydraulique ainsi qu’une nouvelle centrale souterraine placée à mi-parcours de la conduite et sera principalement creusé dans le granite. Les diverses données ont été intégrées à un modèle continu équivalent afin d’évaluer le champ de contrainte régional et ainsi d’extrapoler les résultats des divers tests au volume de masse rocheuse concerné par le plan hydroélectrique. L'intégration des essais in situ et du modèle permet de déterminer les variations spatiales du champ de contrainte. Il est ainsi possible d’identifier le mécanisme de chargement à l’origine du champ de contrainte mesuré ainsi que le comportement rhéologique à long terme du géomatériel équivalent considéré. / A case study is considered in which data produced by different techniques have been gathered in various locations within a rock mass in which topography effects are most likely significant. Measurements were performed for the design of a re-powering scheme that includes a new hydraulic conduit and an underground cavern that will primarily be excavated in granite. An integrated approach for extrapolating the results from the various in situ tests to the rock mass volume of interest for the hydroelectric power scheme is presented. This approach includes the development of an equivalent continuum mechanics model. The integration of in situ tests and numerical modelling enables to determine the stress spatial variation which helps ascertain the loading mechanism at the origin of the measured stress field as well as the long-term rheological behavior of the equivalent geomaterial under consideration.