Pipe–soil interaction analysis of 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. Geotechnical Journal, 33, 3, pp. 393-404, 1996-06-01 Pipe-soil interaction analysis of jointed water mains Rajani, B. B.; Zhan, C.; Kuraoka, S. Canadian

A preliminary analysis of failures in grey cast iron water pipes

“…However, the susceptibility of the pipes to corrosion and their brittle nature are largely responsible for their failure. In general, the external forces that induce grey cast iron pipe failures are understood 3,4 and the physical appearance of those failures are known 3 . Most grey cast iron pipes fail because of a combination of factors that may include external loading, internal pressure, manufacturing flaws and corrosion damage 3,4 .…”

“…In general, the external forces that induce grey cast iron pipe failures are understood 3,4 and the physical appearance of those failures are known 3 . Most grey cast iron pipes fail because of a combination of factors that may include external loading, internal pressure, manufacturing flaws and corrosion damage 3,4 . These failures usually result in one of the standard types of breaks: bell splitting, consisting of an longitudinal break starting at the bell; through-hole corrosion pits; circumferential cracking, where the pipe splits in a circle across its axis; and longitudinal cracking, where the pipe breaks along its axis 3 .…”

“…These relationships are particularly important for grey cast iron pipe, where the dominant failure modes are related to external forces 3 , as opposed to ductile iron pipe, where corrosion pit failures are the most common 10 . Of the studies that do describe this type of failure, one simply differentiates between mechanical and corrosion failures 5 , while another states that most failures are due to combined mechanical and corrosion effects 7 .…”

Estimating time to failure of cast-iron water mains

“…[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. Tesfamariam et al [5] fuzzified these WPSI models to account for (a) uncertainties present in the input data and model parameters, and (b) failure modes using well accepted failure criteria for cast iron to determine the fuzzy factor of safety.…”

“…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.…”