Soil-pipeline interaction along unstable slopes: an uncoupled/coupled 3D approach – Part 1: Theoretical formulation

Pipelines buried along potentially unstable slopes are often monitored because soil movements can induce an evolution of the state of stress within the pipe that can eventually result in the loss of the serviceability of the system or even in its failure. In the present paper, the pipeline is discretised by means of a series of three-dimensional beam finite elements and the soil–pipeline interaction is reproduced by means of macroelements independent from each other, but characterized by a failure condition in which coupling among the different loading components is taken into account. The soil–pipeline interaction problem is formulated by accounting for the geometry of the slope, the soil and pipe mechanical properties, and the imposed soil displacement profile. A convenient piecewise linear formulation for the macroelement constitutive relationship is adopted and a large displacements scheme is also formulated.