Organic soils, also known as peat, cover over 3% of the Earth’s land surface where Canada itself contributes to 25% of global peatland cover. In many cases, buried pipelines traverse through these organic soils that are soft in stiffness, weak in strength and are highly variable in nature. Due to its lower strength properties and very high-water content, organic soils can impose a significant threat to pipeline safety and integrity. Although the current design guidelines provide ways to develop the soil springs for pipelines buried in granular and cohesive soils, none of these guidelines provide explicit recommendations for defining soil springs for pipelines buried in organic soils. This is primarily due to the lack of systematic investigation of the pipe-soil interaction in organic soil. The present study investigates the effect of various pipe-soil interaction parameters for organic soil on the pipeline thermal stress analysis. A total of twelve case studies are performed to study the effect of peak soil resistance, displacement required to mobilize the peak soil resistance, and drained vs undrained definitions of organic soil on the pipeline stresses. Results show that the pipeline stresses depend significantly on these parameters. Besides, depending on the definition of organic soil (drained vs undrained), both bend stress values and locations can change i.e., the drained vs undrained definitions of organic soil can have a significant impact on the pipeline stresses. Therefore, further research with a systematic approach to develop a robust guideline for organic soil definition for pipeline application in terms of pipe-soil interaction is required.
A Critical Review of Pipe-Soil Interaction Modelling Approach in Organic Soil
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