Deformation mechanisms during uplift of buried pipes in sand

Abstract

To investigate the deformation mechanisms during uplift of a pipe buried in sand, a series of tests was conducted in a plane-strain calibration chamber. Image analysis was used to track the soil movement through a window. From an initial embedment of 3 diameters, a model pipe was extracted vertically whilst digital cameras captured the soil movement. Tests were conducted in uniform silica sands with grain sizes varying over one order of magnitude. During uplift, wide zones of distributed shear developed between the pipe shoulders and the ground surface. Beyond peak resistance, the deformation localised into thin shear bands, leading to strain softening behaviour. Particle size did not affect peak uplift resistance or mobilisation distance for the chosen grain size range and cover depth.</p