Analysis of soil-pipeline interaction using ABAQUS/Explicit

It is common in practice (industry as well as in research) to utilise the finite element method for obtaining a solution for pipe-soil interaction problem. There are different finite element methods (such as implicit and explicit) being employed to understand the behaviour of buried pipelines. Implicit finite element solutions, which are always unconditionally stable, are commonly used for soil-pipeline interaction problems. However, this consumes substantial time, memory, storage and in some cases severe convergence problems in reaching towards the final solution. In contrast, explicit finite element calculation is conditionally stable with the use of dynamic finite element formulation. It is more common to use implicit methods for soil-pipeline interaction analyses, but a number of benefits of explicit FE over implicit modelling for pipeline designs have been identified, such as faster simulation time and less numerical problems. To analyse soil-pipeline interaction problems under quasi-static conditions, it is important to conduct analysis with proper control on the stability limits/kinetic energy dissipation of the model. This paper describes how the explicit modelling can be utilised to investigate the behaviour of pipelines under dry as well as unsaturated conditions. In this study, advanced constitutive models that can effectively simulate dry and unsaturated sand behaviour have been implemented into both implicit and explicit solvers, and shown that similar behaviour can be predicted using both the codes. The current study uses the finite element package ABAQUS which has both implicit and explicit solvers inbuilt.