Probabilistic evaluation of primary consolidation settlement of Songdo New City by using kriged estimates of geologic profiles

Abstract

The uncertainty in the spatial distributions of consolidation settlement (s (c)) and time (t (p)) for Songdo New City is evaluated by using a probabilistic procedure. Ordinary kriging and three theoretical semivariogram models are used to estimate the spatial distributions of geo-layers which affect s (c) and t (p) in this study. The spatial map of mean (mu) and standard deviation (sigma) for s (c) and t (p) are determined by using a first-order second moment method based on the evaluated statistics and probability density functions (PDFs) of soil properties. It is shown that the coefficients of variation (COVs) of the compression ratio [C (c)/(1 + e (0))] and the coefficient of consolidation (c (v)) are the most influential factors on the uncertainties of s (c) and t (p), respectively. The mu and sigma of the s (c) and t (p), as well as the probability that s (c) exceeds 100 cm [P(s (c) > 100 cm)] and the probability that t (p) exceeds 36 months [P(t (p) > 36 months)] in Sect. 1, are observed to be larger than those of other sections because the thickness of the consolidating layer in Sect. 1 is the largest in the entire study area. The area requiring additional fill after the consolidation appears to increase as the COV of C (c)/(1 + e (0)) increases and as the probabilistic design criterion (alpha) decreases. It is also shown that the area requiring the prefabricated vertical drains installation increases as the COV of c (v) increases and as the alpha decreases. The design procedure presented in this paper could be used in the decision making process for the design of geotechnical structures at coastal reclamation area.