study of dams behaviour: uncertainties in instrumentation records and numerical modeling.study cases and recent approaches.

Records obtained from dam instrumentation are crucial in order to interpret the structure behavior and be able to assess its safety. However, due to the uncertainties involved in the process of installing such instruments, the way readings are collected, the nature of the instruments and their conservation state, measurements can be under suspect. In fact, measurements can be misunderstood, can lead to make the wrong decisions and even can make dam engineers to develop some degree of skepticism about their importance. In this context, the study of data series by means of statistical models and the implementation of conceptual models may provide results and sensibility analysis that can be very valuable, together with instrumentation records, to get a better understanding of the dam behavior. However, numerical modeling can be a helping tool but also adds some additional uncertainties if they are not carefully and rigorously used: construction data should be examined, constitutive models properly chosen, etc. Also, a statistical analysis can be highly misleading if it is not properly used. In summary, combination of a good knowledge of the instruments, an appropriate conservation and reading procedure, a realistic data management program and the implementation of numerical models are very important tasks that have to be carefully undertaken due to all the involved uncertainties. But also, the behavior itself of a dam, is a source (some times the main one) of uncertainties. Right know, after eight years of a new dam safety legislation in Spain that has promoted lots of instrumentation projects and analysis of dam behaviors, lots of lessons have been learnt. Examples are shown to support the ideas of the article. Finally, as a more recent and very interesting approach, the failure mode analysis undertaken in the context of risk analysis and risk assessment, might allow the dam engineers to focus on what really maters about instrumentation and measurements and decide about the need of new instruments at their site.

Keywords:

Behavior , Uncertainties , Instrumentation , Modeling , Assessment