On the volumetric strain–time curve patterns of dredged clays during primary consolidation

Thirteen one-dimensional consolidation tests with step loading were performed on dredged clays reconstituted at different initial water contents. Both vertical deformation and pore pressure were measured during primary consolidation, which refers to the time-dependent compression process associated with the dissipation of pore pressure. The pore pressure changes were investigated by considering the maximum and the residual values. The development of compression during pore pressure dissipation was analysed to identify the change patterns in volumetric strain–time curves. Three types of change patterns were found during the primary consolidation, and the remoulded yield stress was found to be the key factor in classifying the change patterns. The inflexion point is absent for types 1 and 2, indicating that the end of primary consolidation cannot be determined by the commonly used Taylor and Casagrande methods. Type 3 shows an inverse ‘S’ shape, suggesting that the end of primary consolidation determined based on the compression–time curves occurs before the completion of pore pressure dissipation.