Nonparametric Liquefaction Triggering and Postliquefaction Deformations

AbstractThis study evaluates granular liquefaction triggering case-history data using a nonparametric approach. This approach assumes no functional form in the relationship between liquefied and nonliquefied cases as measured using cone penetration test (CPT) data. From a statistical perspective, this allows for an estimate of the threshold of liquefaction triggering unbiased by prior functional forms, and also provides a platform for testing existing published methods for accuracy and precision. The resulting threshold exhibits some unique trends, which are then interpreted based on postliquefaction deformation behavior. The range of postliquefaction deformations are differentiated into three zones: (1) large deformations associated with metastable conditions; (2) medium deformations associated with cyclic strain failure; and (3) small deformations associated with cyclic stress failure. Deformations are further defined based on the absence or presence of static driving shear stresses. This work presents a single simplified framework that provides quantitative guidance on triggering and qualitative guidance on deformation potential for quick assessment of risks associated with seismic soil liquefaction failure.