Some observations on soil-pipe interface shear strength in direct shear under low effective normal stresses and large displacements

Abstract

Experimental work is undertaken at the University of British Columbia (UBC) to study the soil-pipe interface shear strength at levels of shear displacements and effective normal stresses typically encountered in offshore soil-pipe interaction problems. A macro-scale interface direct shear apparatus having a test specimen footprint of 1.72 m 1.75 m was designed and built for this purpose. The apparatus is capable of testing various soil-pipe interfaces under effective normal stresses in the range of 3 kPa to 6 kPa. A maximum shear displacement of 1.2 m is achievable at rates ranging from 0.1 mm/s to 1 mm/s. Sensors mounted at the interface enable the accurate determination of the effective normal stress at the interface when fully saturated fine-grained soils are tested. This paper presents some observations arising from a series of interface direct shear tests involving fine-grained soils of different plasticity against bare and epoxy coated steel surfaces. Copyright 2016 by ASME.