本文介绍了美国水务协会研究基金会资助的研究项目“周向失败的灰铸铁分配管”目前正在进行中的国家研究理事会加拿大（NRC）调查周向故障在各种各样的装载和土壤条件。它结合了管道试件的机械测试、使用中子衍射法对弯曲管道进行的实验测量和有限元建模。中子衍射可以测量弯曲管道中腐蚀坑周围的应变分布，而有限元建模可以用来确定土壤和荷载条件的变化如何影响管道失效。 将这两种技术结合起来，有可能准确了解导致周向失效的条件，并确定腐蚀坑何时会对水管的完整性构成威胁。该项目涉及三个不同的阶段:从管道样品中获取试件的单轴力学测试、弯曲中管道样品的中子衍射测量和有限元建模。单轴力学试验旨在为项目中使用的铸铁管样品提供适当的应力-应变曲线和泊松比数据，作为有限元建模阶段的输入。 本文第3节描述了机械测试阶段的结果。中子衍射测量显示了管道弯曲部分以及整个管道部分的应变。这些测量将用于检查有限元模型的有效性，并确保弯管中发现的灰铸铁在三轴应力状态下的力学行为完全不受影响。在开始对土壤中的管道进行建模之前，有限元模型需要复制实验观察到的行为。第4节展示了该项目的一些首批中子衍射结果。 最后，有限元建模的未来工作将研究管道、腐蚀坑和周围环境条件之间的相互作用。它应该为不同大小和尺寸的腐蚀坑导致管道过早失效的可能性提供指导。包括15个参考文献、图表。

This paper describes an American Water Works Association Research Foundation funded research project "Circumferential Failures in Grey Cast Iron Distribution Pipes" currently underway at the National Research Council Canada (NRC) to investigate circumferential failures under a wide variety of loading and soil conditions. It combines mechanical testing of pipe coupons, experimental measurements of pipes in bending using the neutron diffraction method and finite element modeling. Neutron diffraction can measure the strain distribution around a corrosion pit in a pipe that is in bending, while finite element modeling can be used to determine how changing soil and loading conditions affect pipe failures. Combining the two techniques gives the potential to produce an accurate understanding of the conditions that cause circumferential failures and to determine when a corrosion pit becomes a threat to the integrity of a water pipe. The project involves three different phases: uniaxial mechanical testing of coupons taken from pipe samples, neutron diffraction measurements on pipe samples in bending and finite element modeling. The uniaxial mechanical testing is intended to provide appropriate stress-strain curves and Poisson's ratio data for the cast iron pipe samples used in the project for use as inputs to the finite element modeling phase. Section 3 of this paper describes results from the mechanical testing phase. The neutron diffraction measurements show the strains in bent sections of pipe as well as whole pipe sections. These measurements will be used to provide a check on the validity of the finite element models and to ensure that the mechanical behavior of grey cast iron in the triaxial stress states found in bending pipes is fully undertstood. The finite element models will need to duplicate the experimentally observed behavior before modeling of pipes in soil begins. Section 4 shows some of the first neutron diffraction results from the project. Finally, future work on finite element modeling will investigate the interaction between the pipes, corrosion pits and the surrounding environmental conditions. It should provide guidance on the potential for premature pipe failure due to corrosion pits of different sizes and dimensions. Includes 15 references, figures.