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Design and Function of Repositories
Published in Roland Pusch, Raymond N. Yong, Masashi Nakano, Geologic Disposal of Low- and Intermediate-Level Radioactive Waste, 2017
Roland Pusch, Raymond N. Yong, Masashi Nakano
Case 2 (Figure 6.26b), where w > qsrf , meaning that w > ksrf at the surface, implying that the water content is medium–high. Here, the depression of soil–water will be considerably higher in the upper portion of the soils, and a thin dried layer, which is called dry crust, will be formed at the surface. The water content will decrease with the depth. Water will move in liquid and vapor form under the gradients of both water potential and temperature. Salt accumulation at the surface is significant and can cause a salt crust at the surface.
Seismic life-cycle cost analysis of ageing highway bridges under chloride exposure conditions: modelling and recommendations
Published in Structure and Infrastructure Engineering, 2018
Shivang Shekhar, Jayadipta Ghosh, Jamie E. Padgett
Although this study considers exposure conditions ranked in terms of increasing severity from marine atmospheric to marine splash to deicing salt exposure, this ranking is qualitative and valid for typical scenarios, or in an average sense. The corrosion deterioration mechanism is often highly uncertain and slight changes in the surrounding atmosphere or climate may result in significant deviations from typical behaviour. For instance, in marine atmospheric zones the quantity of salt deposited on bridge members may vary significantly with wind velocity and direction of wind. During extreme weather conditions, substantial corrosive salt crust formation on these structures may lead to markedly higher corrosion deterioration than usually observed (Roberge, 2008). Similarly, for structures located in the marine splash zone exposure, certain instances of field measurements have revealed corrosion rates higher than deicing salt exposure conditions (Costa & Appleton, 2002; Broomfield, 2006). In addition to the representative exposure conditions given in Table 1, this study also investigates the sensitivity of seismic life-cycle costs on generic measures of corrosion such as mass loss of steel to help decision-makers evaluate seismic losses for atypical scenarios. Discussions and examples are included later in the case-study section of the paper. The following subsections briefly elaborate on the typical exposure cases while discussing the models adopted to estimate the time to corrosion initiation and corrosion rate during the propagation phase. Marine atmospheric and splash zone exposure use a similar set of equations to calculate the onset and extent of deterioration and are discussed first, followed by the deicing salt exposure scenario.