Uplift resistance of buried submarine pipelines: comparison between centrifuge modelling and full-scale tests

A buried pipeline can buckle upwards if there is not enough resistance to movement. Both the uplift resistance (the maximum force per unit length) and the mobilisaion distance (the distance the pipeline has move before the maximum force is reached) are important in design. Tests on pipes in several soils were carried out at 1 g at full scale and in a centrifuge at 10 g and 1/10 scale. A comparison shows that the measured uplift resistances are consistent with the conventional understanding of centrifuge tests, but that the measured mobilisation distances are not consistent with that understanding. Unscaled mobilisation distance in the centrifuge is roughly the same as at full scale. Mobilisation distance does not scale with particle size. This discrepancy is related to the formation of shear zones, and to theory and observations in other areas of the mechanics of brittle materials, among them ice, concrete and heavily overconsolidated clays. An idealised analytical model displays the same behaviour.