This paper will highlight the importance of considering interdependence between pipe-soil interaction springs in a pipe stress analysis. This work focused on a single pipe configuration “wished” in place in a clay soil and was sponsored by the International Pipeline Conference Foundation. A conventional pipe stress analyses often idealizes the pipe soil interaction with a beam-spring finite element model where independence is assumed between reactions in axial, lateral and vertical directions. There is however interdependence between these springs as recognized in recent PRCI guidelines.  For a frictional interface, axial resistance can be much higher than indicated by PRCI guidelines when accounting for increased lateral and vertical bearing pressure.  At the same time, lateral and vertical capacities are shown to be reduced in comparison to pure vertical and lateral loading directions. This paper will highlight the development of a 3D soil-spring interaction model based on a continuum finite element analysis approach.    By developing a soil capacity envelope based on 3D continuum modeling, updated soil springs can reflect modified capacities depending on the direction of pipe movement.  For the constructed landslide scenarios considered in application of the model, the directional dependency is shown to change the accumulated plastic strain profile in the pipe

This paper will highlight the importance of considering interdependence between pipe-soil interaction springs in a pipe stress analysis. This work focused on a single pipe configuration “wished” in place in a clay soil and was sponsored by the International Pipeline Conference Foundation. A conventional pipe stress analyses often idealizes the pipe soil interaction with a beam-spring finite element model where independence is assumed between reactions in axial, lateral and vertical directions. There is however interdependence between these springs as recognized in recent PRCI guidelines.  For a frictional interface, axial resistance can be much higher than indicated by PRCI guidelines when accounting for increased lateral and vertical bearing pressure.  At the same time, lateral and vertical capacities are shown to be reduced in comparison to pure vertical and lateral loading directions. This paper will highlight the development of a 3D soil-spring interaction model based on a continuum finite element analysis approach.    By developing a soil capacity envelope based on 3D continuum modeling, updated soil springs can reflect modified capacities depending on the direction of pipe movement.  For the constructed landslide scenarios considered in application of the model, the directional dependency is shown to change the accumulated plastic strain profile in the pipe


Formulation of 3d Soil Springs for Pipe Stress Analyses

Division / Sponsors: 
Pipeline Systems Division

Paper Proceedings: https://asmedigitalcollection.asme.org/IPC/IPC2020/volume/84447

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