Settlement allowance of the buried pipeline with circumferential surface cracks

In order to ensure the safety of a buried pipeline with circumferential surface cracks, it is necessary to accurately figure out the maximum settlement that the buried pipeline can bear. In this paper, the simulation test on the four-point bend settlement of full-size pipeline was carried out under the design pressure to get the ultimate bearing bending moment of the pipeline with circumferential surface cracks. Then, the finite element model for the settlement simulation test was established, and the ultimate bearing bending moment of the pipeline with circumferential surface cracks was calculated and simulated by taking the fracture toughness as the failure indicator. After the finite element model was verified effectively by the simulation test, a series of ultimate bearing bending moments of the pipeline with circumferential surface cracks of different depths could be obtained. Meanwhile, a pipe-soil model for the uneven settlement of the site was established using the software ANSYS, and the influence of pipeline depth on its bearing bending moment was analyzed. It is indicated from the analysis on the ultimate settlement of the pipeline with circumferential surface cracks of different depths that when the pipeline depth is constant, the ultimate settlement of pipeline failure is in an approximate linear negative correlation with the crack depth. And when the crack depth of pipeline is constant, the ultimate settlement corresponding to pipeline failure is in a nonlinear negative correlation with the pipeline depth.