外文翻译------一个预测埋地pvc管道故障率的物理模型.doc

Reliability Engineering and System Safety 92 (2007) 1258–1266
A physical probabilistic model to predict failure rates in buried PVC pipelines
P. Davis_, S. Burn, M. Moglia, S. Gould
CSIRO Land and Water, Graham Road, Highett, Vic. 3190, Australia
Received 28 September 2005; received in revised form 28 July 2006; accepted 8 August 2006
Available online 29 September 2006
Abstract
For older water pipeline materials such as cast iron and asbestos cement, future pipe failure rates can be extrapolated from large volumes of existing historical failure data held by water utilities. However, for newer pipeline materials such as polyvinyl chloride (PVC), only limited failure data exists and confident forecasts of future pipe failures cannot be made from historical data alone. To solve this problem, this paper presents a physical probabilistic model, which has been developed to estimate failure rates in buried PVC pipelines as they age. The model assumes that under in-service operating conditions, crack initiation can occur from inherent defects located in the pipe wall. Linear elastic fracture mechanics theory is used to predict the time to brittle fracture for pipes with internal defects subjected to combined internal pressure and soil deflection loading together with through-wall residual stress. To include uncertainty in the failure process, inherent defect size is treated as a stochastic variable, and modelled with an appropriate probability distribution. Microscopic examination of fracture surfaces from field failures in Australian PVC pipes suggests that the 2-parameter Weibull distribution can be applied. Monte Carlo simulation is then used to estimate lifetime probability distributions for pipes with internal defects, subjected to typical operating conditions. As with inherent defect size, the 2-parameter Weibull distribution is shown

摘要
对于旧的水渠道材料，如铸铁和石绵水泥，将来的管失效率能从大量现存于供水设施的历史数据中推算出来。然而，新的管道材料，如聚氯乙烯（PVC），只有有限的失效数据的存在，并且有信心预测未来的水管故障不能从单独的历史数据。要解决这一个问题，本文提出一个评估埋地PVC管失效率的实体预测模型。此模型假设在可控的操作条件下，裂缝开始于存在裂纹缺陷的管壁中。线弹性断裂力学理论是用来预测的时间脆性断裂的管道内部缺陷受到内压和土壤偏载和穿墙残余应力。包括不确定性的破坏过程，内在缺陷的大小视为随机变量，并参照适当的概率分布。在澳洲失败的pvc管裂隙表面的显微镜检查指出 2个参数的Weibull分布能被应用。当时的蒙特卡罗法被用来估算在典型的操作条件下存在内部缺陷的管道终生的可能性分配。由于固有的缺陷大小， 2 个叁数的 Weibull 分布被认为很适合做预测管道寿命不确定性的模型。Weibull 的风险功能被用来估计预期的管失效率（笯@ざ龋辏┳魑艿滥炅涞墓δ堋Ｎ搜橹じ媚Ｐ停湓げ獾氖视?7个来自英国水工业研究所（UKWIR）国家电网故障数据库的数据做比较。缺乏 UKWIR 数据库的实际操作压力数据，澳洲水电等公共设施的典型的价值被假定适用了。然而物理概率故障模型与英国供水设施记录的数据显示出良好的一致性，来自英国的实际操作压力被用作模型的验证。