COMPRESSIBILITY OF EXCAVATED AND DREDGED MATERIALS

Abstract

The inclusion of fine-grained soils in reclamation fill presents greater concerns towards long-term creep settlement. This is often improved through surcharge-induced overconsolidation, largely correlated with the OCR parameter. However, OCR alone does not account for the magnitude of the maximum and minimum stresses in the unload-reload cycle, which have been observed to affect primary compression. Understanding the interrelationship between primary and secondary compressibility suggests a corresponding influence on creep improvement. Oedometer tests conducted on a reconstituted clayey soil suggested that an increase in σ’v,max and σ’v,max/σ’v,min each result in less creep reduction at a given OCR, owing to stiffness degradation along the reloading path. Two unique Cα’/Cr values were observed depending on the number of reloading steps. When a single step was applied from unloading, relatively higher Cα’/Cr values were consistently observed. Once preceding reloading steps were introduced, Cα’/Cr was consistent with the Cα/Cc ratio measured in virgin compression.