Research on the indentation behavior and safety evaluation of PE gas pipeline under point load

Abstract

Polyethylene (PE) gas pipelines are often buried underground, and natural settlement of the earth’s ground can cause hard objects in the soil to press against the surface of the pipeline, forming point load. This results in stress concentration and indentation of the pipeline, thereby increasing the risk of failure. Given the rate-dependent nature of PE materials, the Suleiman model is utilized to fit uniaxial tensile test data, thereby obtaining the material’s elastic and plastic parameters. To investigate the denting behavior of buried gas PE pipes under point load, a finite element model of the pipe-soil system under the influence of hard objects is established, and its rationality is verified through point load simulation experiments. This study analyzes the effects of hard object size, internal pipeline pressure, and pipeline diameter on pipeline denting behavior. The deformation rate $\delta$ of the pipe is used as a quantitative metric to evaluate the denting deformation of PE pipes. The results indicate that significant stress concentration and pipeline denting occur at the location of the hard object. Apart from the location of the hard object, the stress and strain variations along the pipeline’s axial direction remain relatively small. Moreover, when the soil settlement remains constant, the deformation rate and its range of variation in pipeline denting remain largely unchanged. The influence of hard object size and internal pressure on pipeline denting deformation is relatively minor, while pipeline diameter has a more significant effect. The results may be referable for safety assessment of PE pipes due to point load.