Application of the fines content correction facor (C_FC) for soils susceptible to liquefaction in the Bay of Plenty

The Cone Penetrometer Test (CPT) has become the most commonly used in-situ test to evaluate simplified triggering methods developed from in-situ and laboratory test data from case histories over the last 50 years.

Engineering properties like the fines content and plasticity index values are shown to have an effect on a soil’s susceptibility to liquefaction. However, relationships used to estimate the fines content using CPT data have a high degree of scatter and hence the actual fines content in soils can be estimated incorrectly, thus potentially incorrectly interpreting liquefaction susceptibility.

This paper will discuss how fines content correction factor (C_FC) values were determined from paired CPTs and boreholes with laboratory testing, and the effects this has on predicted liquefaction susceptibility for a case study in the Bay of Plenty, New Zealand. A range of C_FC values for some soil units were recommended based on the dataset, including recommendations for additional analysis.