Failure criterion of buried pipelines with dent and scratch defects

The excavation of buried pipelines shows that combined dent and scratch defects exist at the bottom of the pipe due to the extrusion and scraping action of rocks, which is likely to decrease its pressure bearing capacity. This paper experimentally investigates the tensile strength of CT80 steel plates with dent and scratch defects. Results show that the tensile strength is affected to varying degrees by dent depth, scratch depth and the indenter diameter. Finite element analysis (FEA) is then carried out to propose the failure criterion by comparing with experimental results. It is thought that failure happens when the equivalent stress of the intermediate node in the direction of the remaining thickness of the defect center of the model reaches the true tensile strength of the material. With this criterion, large numbers of finite element calculations can be developed to study the failure pressure of buried pipelines with combined dent and scratch defects.