碩士 國立臺灣大學 土木工程學研究所 106 Comparing with safety factor method, reliability-based design method can quantify the uncertainty to design geotechnical structure in a more systematical and economical design. In this study, a multivariate probability distribution model for twelve parameters of clay is constructed based on the CLAY/12/8198 database. These twelve parameters are:(1)liquid limit, LL; (2)plastic index, PI; (3)liquid index, LI; (4)vertical effective stress, σv’/pa; (5)vertical effective maximum stress, σp’/pa; (6)sensitivity, St; (7)normalize undrained shear strength, su; (8)the coefficient of earth pressure at rest, K0; (9)undrained modulus, Eu50/su(mob); (10)Bq; (11)(qT-σv)/σv’; (12)(qT-u2)/σv’. Using Johnson distribution system to transform those distributions to standard normal distribution, then applying Gibbs sampler method under condition of conjugation let us get those 12 covariance matrix, mean vector and non-vacancy databases. Afterwards, using the Bayesian analysis framework, the original distrib