ABSTRACT

Most offshore design methods use peak undrained shear strength as the primary input parameter for determining axial capacity of pipe piles driven into clays, e.g. API (2000) Main Text and Kolk & Van der Velde (1996). However, undrained shear strength is not a unique parameter. A particular “reference” laboratory undrained shear strength must be considered, usually defined by some combination of soil sampling method and laboratory test method. For example, API (2000) is largely based on tube push sampling and unconsolidated undrained triaxial compression and miniature vane testing. In practice, “reference” values are commonly inferred from correlations with non-reference values, such as Cone Penetration Test (CPT) inferred values, supplemented by engineering judgement. This practice introduces significant uncertainties in axial pile design (Van der Wal et al. 2010).