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This paper presents results from an experimental and numerical study on the axial–lateral interaction of pipes with dense sand. A series of centrifuge tests were conducted, with a rigid pipeline displaced in the horizontal plane in a cohesionless test bed. The relative pipe–soil interaction included axial, lateral, and oblique loading events. A three-dimensional continuum finite element model was developed using ABAQUS/Standard ( Hibbitt et al. 2005 ) software. The numerical model was calibrated against experimental results. A parametric study was conducted, using the calibrated finite element model to extend the investigations. The ultimate axial and lateral soil loading was found to be dependent on the angle of attack for relative movement between the pipe and soil. Two different failure mechanisms were observed for axial–lateral pipeline–soil interaction. This study confirms and improves on a two-part failure criterion that accounts for axial–lateral coupling during oblique soil loading events on buried pipelines.

The effects of spatial variability of soil properties on the behaviour of saturated soil deposits subjected to seismic excitation are analysed, and their implications for geotechnical design are discussed. A Monte Carlo simulation methodology, combining digital generation of non-Gaussian stochastic vector fields with dynamic, nonlinear finite element analyses, is used for that purpose. The proposed procedure is applied to assess the soil liquefaction potential, which is found to be considerably affected by the inherent spatial variability of soil properties. Parametric studies, involving the degree of soil liquefaction and the frequency content of the seismic input, are performed. Finally, a characteristic percentile value of soil strength, which will predict a response equivalent to that provided by the more expensive Monte Carlo simulations, is proposed for use in deterministic design.