Stress analysis of buried pipes

Pipeline plays a vital role in transporting water, gas and oil from one place to another. Over the years, several failures have been reported in pipeline mainly due to aging (i.e., corrosion). The failure occurs when the stresses in a pipe segment due to applied loads exceed the capacity of the pipe. Therefore, it is important to predict the realistic pipe stress at the design and assessment stages to ensure the safety across the entire lifetime. As significant portion of the pipeline is buried in the underground in most of the occasions, the soil-structure interaction analysis is important as part of the stress analysis. Depending on the location of the network, the pipe will be subjected to varying levels of traffic and pressure loads that need to be accurately determined in order to perform reliable pipe stress estimations. Several pipe stress prediction methods have been developed over the years and reported in the literature. However, these methods are either analytical or empirical based models. The former uses the structural mechanics of the pipe by discarding the complex soil-structure interaction effect while the later fully depends on the experimental results. To overcome these problems, the numerical methods can be used to incorporate the soil-structure interaction effect more efficiently in pipe stress analysis together with traffic and internal pressure loads. In this study, the finite element method is used to analyse the pipe-soil system subjected to external traffic and internal pressure loads. Further, the model developed is used to understand the effect of soil properties, pipeline characteristics, and loading on pipe stress through sensitivity analysis. Finally, the response surface method is used to develop a new pipe stress predictive equation using the results of finite element analyses.