Uncoupled axial, flexural, and circumferential pipe–soil interaction analyses of partially supported jointed water mains

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1139/T04-048Canadian Geotechnical Journal, 41, 6, pp. 997-1010Journal, 41, 6, pp. 997- , 2004 Uncoupled axial, flexural, and circumferential pipe-soil interaction analyses of partially supported jointed water mains Rajani, B. B.; Tesfamariam, S.Uncoupled axial, flexural, and circumferential pipe-soil interaction analyses of partially supported jointed water mains Balvant Rajani and Solomon TesfamariamAbstract: Pipelines used in the distribution of potable water are a vital part of everyday life. The pipelines buried in soil-backfill are exposed to different deleterious reactions; as a result, the design factor of safety may be significantly degraded and, consequently, pipelines may fail prematurely. Proactive pipeline management, which entails optimal maintenance, repair, or replacement strategies, helps increase the longevity of pipelines. The effect of different deterioration mechanisms and operating conditions needs to be understood to develop good proactive management practices. In this paper, a Winkler-type analytical model is developed to quantify the contributions of different stress drivers, e.g., pipe material type and size, bedding conditions, and temperature. Sensitivity analyses indicate that the extent of the unsupported length developed as a result of scour has a significant influence on the flexural pipe-soil response. As well, plastic pipes tolerate less loss of support than metallic pipes.Key words: jointed water mains, Winkler model, pipe-soil interaction, elastoplastic soil. Résumé :Les conduites utilisées pour la distribution de l'eau potable constituent une partie vitale de la vie de tous les jours. Les conduites enfouies dans un remblai de sol sont exposées à différentes réactions nuisibles, et il en résulte une dégradation du coefficient de sécurité utilisé pour le calcul et en conséquence les conduites se brisent prématurément. La gestion proactive des conduites qui comporte des stratégies optimales de maintenance, de réparation, ou de remplacement aide à accroître la longévité des conduites. L'effet de différents mécanismes de détérioration et conditions d'opération doit être bien compris de façon à développer de bonnes pratiques de gestion proactive. Dans cet article, on a développé un modèle analytique de type Winkler pour quantifier les contribut...

Possibilistic approach for consideration of uncertainties to estimate structural capacity of ageing cast iron water mains

“…As noted previously, Rajani and Tesfamariam (2004) recently developed an approach, based on the Winkler-type pipe-soil interaction model, that accounts for the unsupported length (likely to develop as a result of prolonged leakage or washout) and soil elastoplasticity. Further, the axial, flexural, and circumferential stress components were consolidated with the previously reported responses (Ugural and Fenster 1987; to provide an overall picture of the response of buried water mains under the influence of earth, frost, and live loads, water pressure, temperature differential, unsupported length, and pipe-soil interaction.…”

“…Uncertainties in the determination of the remaining service life are further exacerbated by the difficulties associated with obtaining reasonable estimates of past, present, and future corrosion rates. and Rajani and Tesfamariam (2004) have developed Winkler-type pipe-soil interaction (WPSI) models (based on mechanics and hence termed mechanistic or physical models) that account for most of the predominant factors or data-parameters identified earlier. The WPSI may also involve model-associated uncertainties, which occur as a result of model formulation and model parameterscoefficients.…”

“…A possible approach to overcome this limitation is to estimate "probability" or "possibility" of pipe failure by using various methods such as Monte Carlo simulations, analytical methods (e.g., first-and second-order reliability methods), probability-bound analysis (p-boxes), random set theory, and possibilistic analysis using fuzzy arithmetic (Joslyn and Booker 2004). This paper builds on our previous work Rajani and Tesfamariam 2004) in which WPSI models were developed to determine stresses, strains, and displacements at any point along the length of a jointed pipe. In this paper these models are recast in "fuzzy" terms using a possibilistic approach to describe uncertainties in operational factors and input data as discussed earlier.…”

Estimating time to failure of cast-iron water mains

“…Estimation of time to failure is further exacerbated by the uncertainties in determining future corrosion rates. Rajani et al [3] and Rajani and Tesfamariam [4] have developed a Winkler-type pipe-soil interaction (WPSI) model that accounts for most of the factors identified earlier as the predominant contributors to pipe failure. Tesfamariam et al [5] have recently transformed these models into a possibilistic framework to incorporate the uncertainties discussed earlier.…”

“…This paper reveals that the growth rate of a single corrosion pit on cast iron mains is nearly always more detrimental to thin (small diameter) than to thick (large diameter) pipes if all other data or properties remain unchanged. [4] recently developed a Winkler-type pipe-soil interaction model that accounts for the unsupported length (likely to develop as a result of prolonged leakage or wash out) and soil elasto-plasticity. Axial, flexural and circumferential stress responses obtained from these models were consolidated with the previously reported ( [3], [6]) responses, to establish an overall behaviour of buried water mains under the influence of earth and live loads, water pressure, temperature differential, unsupported length and pipe-soil interaction.…”