Modelling of soil-structure interaction behaviour: geometric nonlinearity of buried structures combined to spatial variability of soil

In the analysis of non-linear behaviour of buried structures, the soil-structure interaction is the most important cause of buried pipeline failure, especially when the soil is modelled as a random elastic medium. In order to design safe and economical means of transporting energy and fluid, it is necessary to predict realistic behaviour of buried pipeline. In this work, the influence of spatially random soil properties on the geometric non-linear behaviour of pipeline is investigated. However, a numerical model has been developed, by modelling the pipeline as a geometric non-linear long beam resting on linear elastic random soil. Due to large deflections and moderate rotations of pipeline, the von Karman-type non-linearity based on the finite element formulation of non-linear pipeline response is adopted and then combined with random field theory of soil based on Monte Carlo simulations. The equation of motion is obtained using the principal of virtual works and solved using the Newton-Raphson incremental iterative method. A MATLAB program has been developed to implement the numerical method applied to the non-linear analysis of the buried structure. When the pipeline undergoes large deflection, the spatial variability of soil properties significantly affect the pipeline's response and in this case, the obtained results allow a more reliable design of pipeline.