Evaluation of the Probability of Liquefaction Using Reliability Method and NCEER Suggestions

Methods for evaluations of liquefaction potential in sandy soil are generally based on deterministic approaches. In such concepts and design methods, the variation of soil strength properties and earthquake loads are commonly neglected. Furthermore, deterministic approaches are unable to precisely relate the probability of liquefaction and the safety factor. This problem can be answered by reliability analysis. In this paper, thereliability analysis has been carried out based on the Seed’s well-known method of liquefaction evaluation and the suggestions made by NCEER (1998). Since this method requires quantifying uncertainty values in calculation, one can use statistical moment of indeterminist parameters such as, mean, variance and probability density function (PDF), to determine the most probable uncertainties. Then using advanced first-order secondmoment (AFOSM) technique, reliability index is calculated and the relation probability of liquefaction occurrence, reliability index and safety factor are deduced. The obtained results show the effectiveness of the proposed method.