埋地灰口铸铁管失效预测模型及影响参数分析

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

针对研究解决早期埋设的灰口铸铁管存在的破损频繁、漏失严重等影响输配水安全问题,运用管土相互作用受力模型得到管道应力,结合灰口铸铁管的腐蚀模型、剩余强度评价方法和失效准则,得到管道失效预测模型,最终利用蒙特卡罗方法计算管道可靠度,并进行影响参数分析.计算结果表明:大直径管道失效主要由环向应力控制,而小直径管道失效多为纵向应力控制;由于渗漏或不均匀沉降引起的管道基础局部流失在腐蚀深度超过一定深度时对失效概率的影响较大;腐蚀模型参数、未支撑长度、剩余强度参数对安全因子分布具有重要影响.腐蚀是影响灰口铸铁管失效的重要因素,意在减缓腐蚀速度的管道防腐技术可以有效减少管道的失效频率,延长管道使用寿命.

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.