Failure Prediction Model and Influence Parameter Analysis of Buried Cast Iron Water Mains

Abstract:

To resolve the serious breakage and leakage problems for the cast iron water mains buried in the early years in the water-supply system,pipe stresses were firstly calculated based on the pipe soil interaction model,and the failure prediction model for the cast iron pipe was developed,based on the corrosion model,the residual strength evaluation method and the failure criterion.Monte Carlo (MC) simulations were used to perform the probabilistic analysis,and the influence parameters analysis was given.Results show that pipes in large diameters are often broken because of circumferential stresses,and pipes in small diameters are prone to fail due to longitudinal stresses.The influence on the failure probability is large due to soil bedding lost induced by the breakage or uneven settlement when the corrosion depth reaches a certain depth.The corrosion model parameters,unsupported bedding length,and the residual strength parameters have large influence on the distribution of the safety factors for the cast iron pipe.The corrosion is one of the most important factors leading to the pipe failure.Reducing corrosion pit depth growth by using corrosion control technique can be the most effective way to decelerate the breakage growth rate and prolong the service life.