Service Life Predicting of Dam Systems with Correlated Failure Modes

Abstract

The 50-year design reference period is coming to an end for many dam projects in China. In the last decade, it has become clear that remaining service life analysis of existing dams must be used to optimally manage the growing number of aging and deteriorating structures. The uncertainties associated with deteriorating dams require the use of probabilistic methods to properly assess their lifetime performance. A dam system involves multiple failure modes; however, conventional assessment and prediction models often neglect the correlations among failure modes. As a result, the remaining service life predicted by these methods is relatively rough. First, in this paper, conventional lifetime distribution functions are introduced. The influences of the correlations among failure modes on series, parallel, or series-parallel structure are discussed, respectively, and the approach for calculating correlation coefficients is proposed. Second, on the basis of the analysis of dam failure causes, failure modes of concrete gravity dams are defined, and the concrete gravity dam is reviewed as a series system with parallel subsystems. Third, the limit state functions for failure modes are given, and quantified progressive deterioration functions for various random variables to describe the aging process of gravity dams are obtained. Based on the correlation analysis and time-varying theory, a prediction model of remaining service life for gravity dam systems is finally proposed. An existing concrete gravity dam is investigated. Failure modes and deterioration mechanisms are studied. The results can be used to better predict the remaining service life of deteriorating dams.