A carregar...
Publicação
Probabilistic-based structural safety analysis of concrete gravity dams
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 16.45 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
The construction and operation of dams, associated with the use of water resources,
aims generically at water supplying, the energy producing and, in many cases, flow regulating
and flood controlling.
Considering the dam dimensions and the potential risks associated with its structural
failure, due to the occupation of the downstream valley, and to the costs of the construction,
maintenance and rehabilitation, the use of probabilistic principles in its design, as it is
already performed for other type of structures, is justified considering adequate levels of
safety.
The objections shared throughout the dam engineering community, regarding the
difficulty in estimating the probability of failure for concrete dams, are expectedly overcome
by the failure mode and uncertainty modeling, allowing the application of probabilistic
principles for their safety analysis, based on conservative simplifications regarding the
structural behavior, namely: (i) the definition of the failure surface (dam-foundation
interface); (ii) the consideration of rigid body failure mechanisms; and (iii) the consideration
of the residual shear strength, given only by the frictional component, corresponding to a
limit analysis valid for ultimate limit states.
For that purpose, the failure modes are derived from the current construction and design
practice by comparing analytical and numerical models of a generic, though representative,
case study. The uncertainties involved in the safety of concrete dams are statistically
quantified, through the definition of probabilistic distributions for loads and material
properties, using, in addition to the elements found in the literature, the information
available at LNEC about those features, resulting from the monitoring of the concrete
dam behavior during the construction, first filling and operation periods.
This work explores the required tasks for the adoption of the partial safety factor method for the safety analysis of concrete gravity dams, at the design phase. Two representative
studies regarding the reliability-based design of concrete gravity dams and
partial safety factor calibration are presented, intending to stimulate the discussion on
the applicability of probabilistic principles for the design of concrete dams, as well as,
to influence the safety criteria to be considered in a future revision of the dam safety
regulation.
The obtained results confirm that the seismic load combination and the sliding failure
modes are the most conditioning situations. It is also observed that cross-sections profiles
flatter than currently used may be needed for high intensity seismic zones. Partial safety
factors that approximate reasonably the reliability-based results could be derived.
Descrição
Palavras-chave
Concrete gravity dams Failure mode modeling Uncertainty modeling Reliabilitybased design Partial safety factor calibration