Estimating time to failure of ageing cast iron water mains under uncertainties

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ConferenceComputing and Control in the Water Industry Water Management for the 21st Century: 05 September 2005, University of Exeter, United Kingdom
Pages17; # of pages: 7
Subjectwater mains, corrosion models, pipe-soil interaction model, factor of safety, time to failure, sensitivity analysis; Water mains; Cast iron
AbstractWater distribution networks form essential components of water supply systems in most urban centres. Water mains buried in the soil/backfill are exposed to different deleterious reactions and as a result, their design factors of safety may significantly degrade with time, leading to structural failure. In most cases, a combination of circumstances leads to the failure of a pipe. Factors contributing to pipe failure include operational conditions, design parameters, external loads (traffic, frost, etc.), internal loads (operating and surge pressures), temperature changes, loss of bedding support, pipe properties and condition, and corrosion pit geometry. These are recorded rarely, if at all and it is therefore very difficult to ascertain the precise causes of failure. Even if all this information were available, any attempt to estimate the pipe condition state would involve considerable uncertainty due to large spatial and temporal variability that is inherent in this information. Estimation of time to failure is further exacerbated by the uncertainties in determining future corrosion rates. In this paper, corrosion models and a previously developed analytical model based on Winkler-type pipe-soil interaction are used to estimate time to failure. Since available data are insufficient to establish credible probability distributions, uncertainties in the input data/parameters are handled using possibility theory and fuzzy arithmetic. Sensitivity analyses are carried out to identify the critical data/parameters that merit further investigation.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number48346
NPARC number20378351
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Record identifier13d68571-3470-446b-ab4d-089f4ef6446f
Record created2012-07-24
Record modified2016-05-09
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