Mechanistic development of CPT-based cyclic strength correlations for clean sand

Mechanistic approaches to developing cone penetration test-based liquefaction triggering correlations are presented and evaluated with an application to Ottawa sand. The mechanistic approaches utilize combinations of data from undrained cyclic direct simple shear tests, dynamic geotechnical centrifuge tests with in-flight cone penetration profiles, and cone penetration simulations. Cyclic direct simple shear tests on Ottawa sand characterize the relationship between cyclic resistance ratio (CRR) and relative density (DR). Relationships between cone tip resistance (qc) and DR are developed from geotechnical centrifuge tests and cone penetration simulations. Penetration simulations using the MIT-S1 constitutive model with three different calibrations for Ottawa sand examine the role of critical state line shape and position on simulated qc values. The CRR-DR relationship from laboratory tests is composed with measured and simulated qC-DR relationships via common DR values to develop CRR-qc relationships. An alternative CRR-qc relationship is developed from inverse analyses of centrifuge test sensor array data (i.e., arrays of accelerometers and pore pressure sensors). The results of these different approaches are compared to case history-based correlations for clean sand and their relative merits discussed. Recommendations are provided for future application of these mechanistic approaches to developing liquefaction-triggering correlations of poorly characterized or unique soils.