Problems with interpretation of sand state from cone penetration test

Considerable attention has been given to the inference of sand density from indirect tests, particularly the cone penetration test (CPT). Data from tests performed in large-scale chambers have demonstrated that for a given sand there is an approximately unique relationship between CPT tip resistance, density (or void ratio) and effective stress level. Data have been presented to support the supposition that CPT tip resistance, if normalized by division by the mean effective stress, is uniquely related to the difference between the current void ratio and the void ratio at the steady state at the same mean stress level. The Paper presents a study of chamber test data for the Ticino sand and demonstrates that there is no such unique relationship for this sand. Use of published correlations that fail to recognize this and other potentially important factors could result in interpretations of sand state that, if carried through to design, could in some circumstances be catastrophic. A series of flow slides tha...