The municipal water distribution systems across the world include a significant amount of cast-iron pipes. Many of the buried cast-iron pipes are over fifty years old and require rehabilitation. Municipalities decide on a rehabilitation solution between the replacement and re-use of the existing pipes based on the remaining strengths of the pipes. Fracture mechanics has appeared as the most viable tool for remaining strength assessment of the deteriorating pipes. However, a method of assessing the stress intensity factor (SIF) is often not available to municipal engineers to apply fracture mechanics. This paper presents a method for calculating the SIFs of buried cast iron pipes subjected to corrosion and crack on the exterior surface. Different semi-elliptical-shaped defects were characterized using various aspect ratios (crack-depth to crack-length ratio) and relative depths (crack-depth to pipe thickness ratio). The SIFs were assessed for invert/crown and springline position cracks under internal pressure and vertical surface loads. A simplified method is proposed for evaluating the SIFs of buried pipes subjected to the exterior surface defects.

全世界的市政供水系统包括大量的铸铁管。许多埋入式铸铁管已有五十多年的历史，需要修复。市政当局根据管道的剩余强度，在更换和再利用现有管道之间决定一种修复解决方案。断裂力学已成为评估不断恶化的管道剩余强度的最可行工具。但是，市政工程师通常无法使用评估应力强度因子（SIF）的方法来应用断裂力学。本文提出了一种计算埋入式铸铁管外表面腐蚀和开裂的SIF的方法。使用各种纵横比（裂纹深度与裂纹长度之比）和相对深度（裂纹深度与管道厚度之比）来表征不同的半椭圆形缺陷。在内部压力和垂直表面载荷作用下，对SIF进行了倒/冠和弹力线位置裂缝的评估。提出了一种简化的方法来评估承受外表面缺陷的埋管的SIF。