Probabilistic evaluation of spatial distribution of secondary compression by using kriging estimates of geo-layers

This paper presents a procedure for evaluating the spatial uncertainty in the secondary compression (ss) using a probabilistic method. In order to evaluate the spatial distribution of ss, the spatial maps of three geo-layers (the thickness and depth of the consolidating layer, the bottom elevation of the reclaimed sandfill) are estimated by using kriging techniques. For all three geo-layers considered in this study, the ordinary kriging is found to give more reliable estimates than the kriging with a trend and simple kriging. It is observed that the coefficients of variation (COVs) of Cα/Cc and Cc/(1 + e0) have similar influences on the COV of ss. It is also shown that the COV of cv has less effect on the COV of ss than the COVs of Cα/Cc and Cc/(1 + e0) although the COV of cv is larger than that of Cα/Cc and Cc/(1 + e0). The COV of ss evaluated by considering all the COVs of soil properties is 0.420, which is 1.4–2.7 times larger than that determined by considering the COV of an individual soil property separately. It is observed that the area exceeding a design criterion increases as the COV of Cα/(1 + e0) increases and the probabilistic design criterion (α) decreases. For Songdo New City, the area ratio decreases from 0.47 for α value of 0.05 to 0.04 for α value of 0.45. The design procedure presented in this paper could be used in the decision making process for a geotechnical engineering design.