Case Study: Risk Analysis by Overtopping During an Upstream Landslide in Peñitas Dam, Mexico

Risk and uncertainty analysis by mathematical and statistical methods is often used to assess systematic risks and uncertainties. This research presents the procedure and application of risk and reliability analysis to dam overtopping (Peñitas) located downstream of a natural dam that could have failed. For the analysis are used six statistical variables and their uncertainties, the peak flood of the upstream dam, are evaluated with empirical formulas. The highest water levels of the break dam event were computed using reservoir routing with an explicit equation developed by the authors. Afterward, the overtopping risk analysis of Peñitas Dam was assessed for different stages of excavation of the natural dam that were made during making a sensitivity analysis of duration of dam break event, and also is calculated the possible upper elevation of Peñitas dam, finding that is a recommended practice measurement in similar further cases. A methodology to do an orderly and consistently analysis of risk is proposed to solve similar situations.

Optimal Failure-Finding Intervals for Heat Shields in a Gas Turbine Combustion Chamber Using a Multicriteria Approach

When a component, as heat shields, degrade, two stages can be distinguished. First, a potential failure appears, which could evolve to the second stage and become a functional failure. The time between these two stages is called delay-time, which has been widely studied in literature to determine when to inspect to avoid breakdown. These studies have shown only single analysis criteria to find failure finding interval (FFI). In order to overcome this limitation, we developed a novel strategy to apply multicriteria methodology to optimize FFI. Our approach considers availability, system breakdown risk and reliability analysis from a systemic perspective, studying heat shields as groups, according to their location in the combustion chamber, regardless of age defect. Hence, it is not necessary to check every one of the shields. Our results show an optimal FFI policy subject to a determined breakdown risk level. This analysis may be adaptable to other components that can be grouped together.