Soil-pipeline interaction along unstable slopes: an uncoupled/coupled 3D approach – Part 2: Numerical analyses

The soil–pipe interaction constitutive model, based on the concept of the “macroelement” described in a companion paper, has been implemented according to a piecewise linear (PWL) formulation in a three-dimensional finite element code in which the pipe is discretised by means of beam elements. To draw an interpretative theoretical framework for the structural response of the system, some ideal problems in which the pipeline is assumed to be straight and the displacement profile simple are discussed. Both large and small displacement approaches are employed, and the problem of axial instability of pipelines is also analysed. Monitoring data from three real case studies have also been numerically simulated: the first two concern pipelines subject to transversal slow soil movements and the third one refers to a small diameter pipeline subject to failure due to axial instability.