Effect of Near-Surface Crustal Layers on Undrained Vertical Penetration Response of Subsea Pipelines

Large deformation finite element analyses were performed to study the undrained vertical bearing capacity of subsea pipelines installed on a surficial high-shear-strength crust overlying a soft clay deposit. A detailed parametric study was carried out for different combinations of shear strength ratio of crust to underlying soil, crust thickness, and strength heterogeneity of the underlying soil. Results show that the presence of a crustal layer significantly influences the vertical penetration response of pipelines. Simple relationships are developed to predict the maximum penetration resistance and the displacement required to mobilize the maximum resistance for the assessment of punch-through failure