Abstract:The theory of random field plays an important role in reliability analysis of foundations. The key to application of random field theory to reliability analysis is how to combine the reduction function of variance obtained by the random theory with the reliability theory. Based on a large amount of investigation data in Tianjin Port,a random field model is established for the soil profiles in this area. The correlation function,correlation distance and irrelated distance are studied and the representative values of them of local area are provided. In addition,how to correctly choose the reduction function of variance and to reasonably apply it to the reliability analysis is discussed. The principle for determination of reduction function of variance is presented and applied to the probabilistic slope stability analysis. It is proven that the reliability indexes obtained by reducing the variance of shear strength indexes according to this principle agree well with the reliability of practical engineering. The developed method may give guidance to introduce the theory of random field into reliability analysis of soil foundations. Finally,the sensitivity analysis of parameters c and j in reliability calculation of slope stability is carried out. It is concluded that the effect of parameter j is larger than that of parameter c.