Comparison of measured and calculated consolidation settlements of thick underconsolidated clay

This study investigates the consolidation settlement of thick deep deposit of underconsolidated clay encountered east of Port Said in Egypt. The foundation soil of the studied area includes a 35 m thick deposit of very soft to medium stiff silty clay. Calculated settlements for a container terminal constructed in this area are compared with two years of field measurements. Consolidation parameters were defined for this site from laboratory and cone penetration tests (CPT). Upper and lower bounds of calculated settlements were calculated using one-dimensional consolidation theory for the range of working container loads. Settlement monitoring was conducted using settlement plates at eight (8) locations. Field measured settlements were compared to calculated settlements to validate the soil properties and evaluate the rationality of the calculated settlements. Field measured settlements fell within the upper and lower bounds of the calculated settlements. The results of this study confirmed that the deep clay deposit is underconsolidated, which poses a geotechnical challenge to potential construction in this area due to expected excessive settlements. In addition, the study showed that applying the one-dimensional consolidation theory using consolidation parameters estimated from CPT and laboratory tests for underconsolidated clays reasonably estimated the magnitude and rate of consolidation settlement.