When Clay Secondary Consolidation Helps: Two Case Studies

摘要

This paper describes two field case histories in which the consideration of pseudo-overconsolidation due to clay secondary compression process helped in the accomplishment of national projects in Egypt. In the first case, renovation of the 45-years old Cairo airport involved increasing the contact stress on some of the existing isolated footings by 46 %. Building age, architectural require-ments, operation conditions precluded construction of additional columns. Variation in the underlying silty clay layer thickness and distance to the foundation level enhances the potential for differential settlement problems due to the renovation. Considering the effect of clay pseudo-overconsolidation resulted in reduced calculated differential settlement values and consequently executing the renovation. The second case involved construction of buildings and dikes for an engineered wetland on a marine deposit of soft clay. The general practice of using either deep foundation or soil improvement was avoided by considering the effect of clay overconsolidation in settlement calculations.