Efficient Approach to Simulate Soil–Pipeline Interaction

It is common in practice to utilize finite elements for obtaining a solution for soil–structure interaction problems. There are different finite-element methods (such as implicit and explicit) being employed at present to understand the behavior of buried structures. Implicit finite-element solutions, which are unconditionally stable, are more common to use for soil–structure interaction in spite of excessive analysis time, memory usage, storage requirement, and converging issues. On the other hand, an explicit finite-element method that uses dynamic finite-element formulation is conditionally stable, but can be used to analyze soil–structure interaction problems under quasi-static conditions. This paper describes an overview of the two solvers and how they can be used to analyze soil–structure interaction problems using buried pipeline as an example in Abaqus. The paper also elaborates how the explicit method can be used to model the behavior of unsaturated soils under undrained conditions. User-defined advanced constitutive models were developed to capture the behavior of dry, partially saturated, and fully saturated soil behavior in conjunction with implicit as well as explicit platforms. The results of the developed codes in Explicit are validated by comparing with the results of the equivalent coupled pore fluid diffusion and stress analysis using simulated single-element triaxial tests. The developed codes in the explicit algorithm were also verified against the results obtained from physical triaxial test data and large-scale pipe–soil tests conducted in dry as well as in unsaturated soil mediums. The formulated models under explicit algorithms provide great benefits that include fast simulation time and less numerical problems for conducting three-dimensional finite-element simulations on soil–structure interaction analysis.