Browsing by Author "Fall, M."

In this paper, a multi-method approach for the assessment of the stability of natural slopes and landslide hazard mapping applied to the Dakar coastal region is presented. This approach is based oil the effective combination of geotechnical field and laboratory works, of GIS, and of mechanical (deterministic and numerical) stability analysis. By using this approach, valuable results were gained regarding instability factors, landslide kinematics, simulation of slope failure and coastal erosion. This led to a thorough assessment and strong reduction in the subjectivity of the slope stability and hazard assessment and to the development of an objective landslide danger map of the SW coast of Dakar. Analysis of the results shows that the slides were influenced by the geotechnical properties of the soil, the weathering, the hydrogeological situation, and the erosion by waves. The landslide susceptibility assessment based on this methodological approach has allowed for an appropriate and adequate consideration of the multiple factors affecting the stability and the optimization of planning and investment for land development in the city. (C) 2005 Elsevier B.V. All rights reserved.

In an attempt to characterize material intrinsic reactivity, iron dissolution from elemental iron materials (Fe(0)) was investigated under various experimental conditions in batch tests. Dissolution experiments were performed in a dilute solution of ethylenediaminetetraacetate (Na(2)-EDTA - 2 mM). The dissolution kinetics of 18 Fe(0) materials were investigated. The effects of individual operational parameters were assessed using selected materials. The effects of available reactive sites [Fe(0) particle size (<= 2.0 mm) and metal loading (2-64 g L(-1))], mixing type (air bubbling, shaking), shaking intensity (0-250 min(-1)), and Fe(0) pre-treatment (ascorbate, HCl and EDTA washing) were investigated. The data were analysed using the initial dissolution rate (k(EDTA)). The results show increased iron dissolution with increasing reactive sites (decreasing particle size or increasing metal loading), and increasing mixing speed. Air bubbling and material pre-treatment also lead to increased iron dissolution. The main output of this work is that available results are hardly comparable as they were achieved under very different experimental conditions. A unified experimental procedure for the investigation of processes in Fe(0)/H(2)O systems is suitable. Alternatively, a parameter (tau(EDTA)) is introduced which could routinely used to characterize Fe(0) reactivity under given experimental conditions. (C) 2009 Elsevier B.V. All rights reserved.