The Effects of Liquefaction Criteria on the Results of Cyclic Triaxial Tests

Cyclic triaxial tests have been used to evaluate the liquefaction susceptibility of cohesionless soils since the 1960s. While there is general agreement of test procedure for cyclic triaxial tests, one aspect of cyclic triaxial testing that is not standardized is the criterion chosen as the definition of liquefaction. The definition of liquefaction used to evaluate the cyclic triaxial test data can have a significant effect on subsequent analyses. In an attempt to quantify the effects of different liquefaction criteria, the results of over 250 cyclic triaxial tests were evaluated under a series of stress-based and strain-based liquefaction criteria. During this evaluation, a special focus was placed on the effects of specimen relative density and non-plastic fines content on the results obtained using different liquefaction criteria. It was found that if the soil is susceptible to flow liquefaction failures, there is little difference in the number of cycles of loading to cause liquefaction among the different failure criteria evaluated. Conversely, if the soil is susceptible to cyclic mobility/limited liquefaction failures, the number of cycles of loading to cause liquefaction varied significantly between the various failure criteria.