CPT-based liquefaction analysis, Part 2: Reliability for design

This paper is the second of a set of two papers that address the issue of earthquake-induced Liquefaction potential. lo the present study, a probabilistic approach is taken to analyse field Liquefaction performance records. The CPT-based limit state function for liquefaction resistance assessment presented in the first paper forms the basis for this probabilistic analysis. At the limit state, the liquefaction resistance of a soil, expressed as cyclic resistance ratio (CRR), is equal to the critical cyclic stress ratio (CSR), known as the seismic load. A reliability technique is used to analyse the 225 case records using the established limit state function and considering uncertainties in the input parameters. The probabilities of liquefaction are inferred from the calculated reliability indices based on Bayes' theorem. A mapping function between the factor of safety and the actual probability of liquefaction based on held case records is developed. The factor of safety, calibrated to the actual probability of liquefaction, can thus form the basis for rational design decisions.