One of the most novel technologies developed in the past few decades is to convert mine wastes into cemented construction materials, otherwise known as cemented tailings backfill (CTB). CTB is an engineered mixture of tailings (waste aggregates), water and hydraulic binders. It is extensively used worldwide to stabilize underground cavities created by mining operations and maximize the recovery of ore from pillars. Moreover, the application of CTB is also an environmentally friendly means of disposing potential acid generating tailings underground. During and after its placement into underground mine excavations or stopes, complex multiphysics processes (including thermal, T, hydraulic, H, mechanical, M, and chemical, C, processes) take place in the CTB mass and thus control its behavior and performance. With the interaction of the multiphysics processes, the field variables (temperature, pore water pressure, stress and strain) and geotechnical properties of CTB undergo substantial changes. Therefore, the prediction of the field performance of CTB structures during their life time, which has great practical importance, must incorporate these THMC processes. Moreover, the self-weight effect, water drainage through barricades, thermal expansion and chemical shrinkage can contribute to the volumetric deformation of CTB. Consequently, CTB exhibits unique consolidation behavior compared to conventional geomaterials (e.g., soil). Furthermore, the consolidation processes can result in relative displacement between the rock mass and CTB. The resultant rock mass/CTB interface resistance can reduce the effects of the overburden pressure or the vertical stress (i.e., arching effect). Hence, a full understanding, through multiphysics modeling and simulation of CTB behaviors, is crucial to reliably assess and predict the performance of CTB structures. Yet, there are currently no models or tools to predict the fully coupled multiphysics behavior of CTB. In this Ph.D. study, a series of mathematical models which include an evolutive elastoplastic model, a fully coupled THMC model, a multiphysics model of consolidation behavior and a multiphysics model of the interaction between the rock mass/CTB interface are developed and validated. There is excellent agreement between the modeled results and experimental and/or in-situ monitored data, which proves the accuracy and predictive ability of the developed models. Furthermore, the validated multiphysics models are applied to a series of engineering issues, which are relevant for the field design of CTB structures, to investigate the self-desiccation process, consolidation behavior of CTB structures as well as to assess the pressure on barricades and the strength development in CTB structures. The obtained results show that CTB has different behaviors and performances under different backfilling conditions and design strategies, and the developed multiphysics models can accurately model CTB field behavior. Therefore, the research conducted in this Ph.D. study provides useful tools and technical information for the optimal design of CTB structures.

Cette thèse se donne pour objectif principal l’explication de l’hétérogénéité que l’on observe en matière de conformité au sein des multinationales. En particulier, je m’intéresse à ce qui pousse les filiales d’une multinationale à mettre en œuvre des pratiques conformes à la politique définie par le siège. Compte-tenu des pressions normatives croissantes exercées sur les multinationales, leur gestion de la conformité interne prend une importance stratégique. Et la responsabilité sociale d’entreprise (RSE) compte au nombre de ces normes émergentes. Mon travail repose sur des données uniques (dont des enquêtes, des données d’archive et des entretiens) sur la mise en œuvre de pratiques RSE que j’ai collectées de 2012 à 2014 au sein d’une multinationale. Dans l’ensemble, les résultats de mes trois essais démontrent que les niveaux hétérogènes de conformité que l’on observe au sein des multinationales résultent certes des différentes pressions internes et externes exercées sur leurs filiales, mais également (1) de leurs divers niveaux d’attention aux demandes normatives en fonction de la conformité de leurs pairs, (2) de leur internalisation de la politique groupe qui limite l’influence du siège et de leurs pairs et (3) des caractéristiques spécifiques et des niveaux d’institutionnalisation des diverses pratiques. / The main objective of this dissertation is to explain heterogeneity in conformity within multinational enterprises (MNEs). More specifically, I focus on what makes an MNE’s subsidiaries implement practices that are consistent with the policy designed by the MNE’s headquarters. Given the increasing normative pressures on MNEs, managing conformity within them is of strategic importance. Corporate social responsibility (CSR) is an example of such mounting norms. My work relies on a unique set of data (including surveys, archival data and interviews) I collected on CSR practices in one MNE between 2012 and 2014. Overall, the findings of my three essays show that heterogeneous conformity within MNEs stems not only from diverse internal and external pressures exerted on subsidiaries, but also from (1) the subsidiaries’ varying levels of attention to normative demands that depend on peers’ behaviors, (2) their heterogeneous internalization of the Group policy which reduces peers’ and headquarters’ influence and (3) the specific characteristics and institutionalization levels of different practices.

The thesis deals with the manifestation of coupling processes of various timescales in the middle atmosphere. Longer and shorter timescales are represented here by the 11-year solar cycle (SC) and orographic gravity waves (oGWs) considered on the intraseasonal timescale of the north hemisphere winter, respectively. The first two chapters deal with the application of rigorous attribution the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the SC using multiple nonlinear techniques (support vector regression and neural networks) besides the multiple linear regression approach. The aliasing of the SC with volcanic eruptions or the El Niňo Southern Oscillation is qualitatively assessed and its impact on conclusions about the top-down coupling mechanisms discussed. The last chapter examines the role of parametrized oGWs in the lower stratosphere. The Himalayan hotspot reveals common features with sudden stratospheric warmings such as the residual circulation amplification leading to a warming and ozone enrichment in the polar latitudes of the lower stratosphere.