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1、 西南交通大学毕业设计（论文） 第35 页 西 南 交 通 大 学本科毕业论文外文资料翻译年 级:2008级学 号:20080156姓 名: 专 业:土木工程指导老师: 2012年 6 月Reliability Engineering and System Safety 92 (2007) 12581266A physical probabilistic model to predict failure rates in buried PVC pipelinesP. Davis_, S. Burn, M. Moglia, S. GouldCSIRO Land and Water, Graham
2、 Road, Highett, Vic. 3190, AustraliaReceived 28 September 2005; received in revised form 28 July 2006; accepted 8 August 2006Available online 29 September 2006AbstractFor older water pipeline materials such as cast iron and asbestos cement, future pipe failure rates can be extrapolated from large vo
3、lumes 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 pre
4、sents 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 the
5、ory 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,
6、 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 f
7、or pipes with internal defects, subjected to typical operating conditions. As with inherent defect size, the 2-parameter Weibull distribution is shown to be appropriate to modeluncertainty in predicted pipe lifetime. The Weibull hazard function for pipe lifetime is then used to estimate the expected
8、 failure rate (per pipe length/per year) as a function of pipe age. To validate the model, predicted failure rates are compared to aggregated failure data from 17 UK water utilities obtained from the United Kingdom Water Industry Research (UKWIR) National Mains Failure Database. In the absence of ac
9、tual operating pressure data in the UKWIR database, typical values from Australian water utilities were assumed to apply. While the physical probabilistic failure model shows good agreement with data recorded by UK water utilities, actual operating pressures from the UK is required to complete the m
10、odel validation.1. IntroductionPolyvinyl chloride (PVC) pipes have been used in Europe and Australia since the early 1960s and in North America since the late 1970s. They are currently used in 80% of the water reticulation market in North America. As described in a number of studies, PVC pressure pi
11、pes have exhibited relatively low failure rates in service compared to other pipe materials in use. For example, a Canadian study 1 indicated that un-plasticised polyvinyl chloride (PVC-U) pipes have fewer line breaks than traditional materials including ductile iron and a more recent extensive stud
12、y confirmed the low failure rate for PVC-U in the United States 2. In Australia, PVC-U pressure pipes installed in the early 1970s in a large rural water supply scheme have been exhumed and examined 3. The pipes were considered to represent Australian quality at that time and over a service life app
13、roaching 30 years, no failures occurred apart from those attributed to third-party damage or poorly manufactured solvent cement joints. However, in other instances premature field failures have been reported in PVC-U pipes, and have been attributed to poor installation, excessive operating condition
14、s or third-party damage.In other cases, failures have been attributed to poorly manufactured pipes. Almost invariably, PVC-U pipe failures in the field occur by cracks initiating from stress concentrations in the pipe wall 4 and as PVC-U pipe usage increases, the economic, environmental and social c
15、onsequences of these premature fracture failures also increases. Generally where failure data is plentiful, statistical methods are used to predict pipeline failure and as a first approximation, water main breakage rates are often described by fitting time-exponential functions to this recorded failure rate data. Although future failure rates can be extrapolated 5,6, forecasts are generally restricted to homogeneous groups of pipes (or cohorts) with similar attributes 7. While these statistical techniques continue to be widely used for water pipeline asset management, they also require larg
