Volume 21, Issue 2 (June 1998)
Evaluation of True Cν and Instantaneous Cν, and Isolation of Secondary Consolidation
It is shown that the presence of a distinct straight line in the initial portion of settlement versus the square root of time plot indicates that soil follows theoretical behavior and that there is no initial and secondary compression in the straight line portion. If the coefficient of consolidation, cν, is determined using the data of only this portion, it can be regarded as the true cν. Secondary consolidation essentially starts after 60% consolidation and runs superposed over the primary consolidation. Its effect is to gradually decrease cν so that at every instant of time it is a new Terzaghian soil with a new cν and other consolidation parameters. Characteristics of linear and semi-log plots of U versus U, where U is the degree of consolidation and U is the theoretical velocity, are used for determining true cν and instantaneous cν, and for isolation of secondary consolidation from the experimental consolidation curve.