Interface shear box tests for assessing axial pipe-soil resistance

The clay-interface shear resistance is an important parameter for the design of offshore pipelines, which slide on the seabed as a result of thermally induced expansion, contraction and lateral buckling. This paper presents a methodology for characterising the clay-interface resistance and quantifying the effect of drainage and consolidation during or in-between shearing episodes. Models for describing the clay-interface resistance during planar shearing are presented and compared to test data for a range of drainage conditions from drained to undrained and including the case of episodic consolidation. The test data are from two series of interface shear box tests carried out on marine clays. The effects of normal stress level (in the low stress range), overconsolidation and interface roughness are also examined.