Centrifuge modeling of differential settlement and levee stability due to staged construction of enlarged embankment

Many old levees along major rivers in South Korea have been reinforced by enlargement construction. Conventionally, the design settlement is simply estimated without considering variations in the material properties of the foundation layer underneath existing and enlarged embankments. A case study on an actual enlarged embankment located near Buyeo along the Kum River was performed using centrifuge tests. First, construction of the existing part on a soft foundation layer of kaolin clay was simulated. Second, enlargement of the existing embankment was simulated. The deformation pattern and differential settlement were then observed. After the enlargement simulation, block samples were extracted from the foundation layer for consolidation tests. The deformation pattern of the embankment was analyzed using GeoPIV. Clear differential settlement occurred and caused a tension crack in the enlarged embankment simulation test. The conventional method estimated a design settlement that was different from the measured settlement, and the differential settlement between foundations under the existing and enlarged embankments could not be estimated. Material properties from the consolidation tests differed depending on the location, and the foundation settlement differed according to the acquiring method. Based on these findings, design settlement should be estimated by considering the differential conditions of an actual field.