Mechanical response analysis of pipeline under settlement based on pipe-soil interaction model

Abstract

Long-distance pipelines have significant advantages in terms of low investment, transportation cost and high safety, which make pipeline networks expand. Pipelines inevitably pass through the collapsible loess areas in northwest China, suffering from subsidence and other disasters. To accurately analyze the effect of subsidence on the stress-strain of pipelines, the pipe-soil interaction model based on the soil constitutive model (PSIMBOSCM) was proposed to accurately obtain the soil spring performance parameters. The results of pipeline stress monitoring were numerically analyzed, and the accuracy of the model was verified. The influence of key factors such as pipe diameter, wall thickness, internal pressure, loess internal friction angle and loess moisture content on the stress-strain state of a gas pipeline under the operation were systematically studied. The results of the study showed that the finite element model of the mechanical response of buried pipeline under geological action was established and verified by in-situ monitoring data of the buried pipeline. The average relative error between the stress monitoring results and the finite element calculation results was 7.8 %. The dangerous position of the pipeline within the settlement area was located in the middle of the settlement area, and the safe settlement threshold and ultimate settlement threshold of the pipeline were 2.3 m and 3.7 m, respectively. Decreasing pipe diameter and increasing the wall thickness are effective ways to improve the bearing capacity of buried pipelines. Internal pressure has minimal influence on the mechanical response of pipelines under settlement. The loess moisture content is negatively correlated with pipeline stress, and the loess internal friction angle shows a positive correlation with pipeline stress. This research can provide valuable technical basis for the safe operation of pipelines in collapsible loess settlement areas.