Since the mid-1970s, various pipe-soil interaction (PSI) models have been developed to estimate the strain demand imposed on buried pipelines by the movement of the surrounding soil. These PSI models can be broadly divided into four categories: analytical models, soil-spring models, full continuum models and discrete element method models. These models can be used for strain-based design, fitness-for-service evaluation of in-service pipelines, and post-event failure analysis.

In this paper, the working principles and modeling characteristics of the four types of PSI models for strain demand estimation are briefly reviewed and summarized. Analytical models calculate the bending and/or membrane strains from functions that describe the deflected profile of the pipe. The other three types of models utilize finite element (FE) modeling to predict the pipe displacement and the corresponding strain demand under given soil movement patterns. The primary difference between the three types of PSI FE models is the representation of the soil geometry and its interaction with the pipe. The four types of PSI models have their own strengths and limitations, which are discussed in terms of their applicability, accuracy, and the level of effort needed for model application. Two case studies were presented to demonstrate the potential differences in strain demand estimates using different PSI models.

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