Assessment of liquefaction potential using optimum seeking method

The use of the cone penetration test (CPT) resistance data as an index for liquefaction assessments is receiving increased attention because of the advantages of this in-situ test method. This paper investigates the feasibility of using the optimum seeking method to assess liquefaction potential from actual CPT field data. Optimization theory is a very important branch of applied mathematics, and has a wide application in the practical world. Using the available field liquefaction and nonliquefaction data, the influence of various factors is quantified using the optimum seeking method. The factors considered are: the earthquake magnitude, M; the vertical effective overburden stress, sigma'(nu 0) the CPT tip resistance, q(c); the peak acceleration at the ground surface of the site, a(max); and the median grain diameter of the soil, D-50. The most important factor has been identified as the CPT tip resistance. Since neither normalization of q(c) nor calculation of seismic shear stress is required, the proposed method is simpler than the conventional method of evaluating liquefaction potential. Comparisons indicate that the proposed method gives a rate of success for evaluating liquefaction potential equivalent to or somewhat higher than that by the conventional method.