Mechanical Behavior Analysis of Buried Elbow Pipelines through Nonuniform Subsidence Regions

Nonuniform subsidence of soil is a major geohazard faced by long-distance pipelines, and elbows in the subsidence zone are more likely to have stress concentrations. Therefore, obtaining the peak stress of the elbow is crucial for pipeline safety assessment. Related studies are dominated by numerical simulations; however, to our best knowledge, there is insufficient discussion of the soil parameters as well as the radius of curvature to obtain predictive models. In this paper, a nonlinear finite-element method is used to establish the numerical model of buried elbow pipeline under the nonuniform subsidence. By comparing with the existing studies and the numerical results in this paper, we verify the reasonableness of the model, which has the advantages of short time-consumption and high accuracy. The finite-element software is used to establish the soil-spring model of the X60 oil pipeline, and the stress analysis is carried out under the nonuniform subsidence. Here, we analyze the effects of subsidence, pipe size, loading, and soil dimensionless parameters on peak stresses in elbows. In addition, the article analyzes the Pearson’s correlation between the peak stress of the elbow and each parameter. Based on the numerical results, a prediction model for the peak stress of the elbow is derived, and a multiparameter coupling form is discussed. The results can provide scientific guidance for the safety assessment of buried elbow pipelines in areas of nonuniform soil subsidence.