Ian Moore Research

Frost induced failure of cast iron water pipes

IDM 27/7/05

Typical corroded water pipe, City of Hamilton, 2003.

Three dimensional ground movements from frost damage analysis, Trickey (2005).

Bending moments near transition from granular to frost susceptible pavement subgrades; three different frost conditions (ice lenses bring pipe close to moment capacity Mf), Trickey (2005).

Typical costs of water pipe replacement of $50/a per resident imply investments of $15B each year across Canada. These huge expenditures are prioritized by municipal engineers based on break rate data, and much needs to be learned regarding the causes and potential prevention of fractures. About 80% of grey cast iron pipe failures in Ontario are by ring fracture during or immediately following ground freezing. NSERC funding is being used to develop rational explanations for these failures. Trickey (MSc, 2005) has developed three dimensional finite element procedures to examine bending in pipes under transitions between frost susceptible and non-frost susceptible pavement structures. These demonstrate how typical thermal conditions can produce ring fractures as a result of differential ground movements, and provide guidance regarding the effect of material and geometrical conditions like the stiffness of the backfill soil and the burial depth.