Stress intensity factors for an axially oriented internal crack embedded in a buried pipe

In this paper, the finite element method has been used to study the effect of soil weight on the stress intensity factors of an axially oriented semi-elliptical crack located on the inner surface of a buried pipe. The Burns and Richard model has been utilized to take into account the interaction between the soil and the pipe. The finite element results revealed that the cracks in a buried pipe are subjected to mixed mode loading. The mode I and mode II stress intensity factors depend on the circumferential location of internal crack. KI is always significantly larger than KII and is maximum when the internal crack is along the vertical direction. A comparison between the results of two-dimensional and three-dimensional cracks also signified that the two-dimensional analysis always represents more conservative results. Depending on the crack aspect ratio (a/c), the discrepancy between the results of two and three-dimensional analyses can be significant.