A new interpretation of the constant rate of strain consolidation test for determining the coefficient of consolidation

This study presents a new method to determine the coefficient of consolidation from a constant rate of strain consolidation test. The method rests on the direct measurement of the total vertical stress applied at the top of a double drained clay specimen. For a sufficiently small time increment, the rate of stress is practically constant and is equivalent to a ramp-loading over the considered time interval. Consequently, a one dimensional consolidation theory was developed for the special case of a double-drained clay specimen subject to a constant rate of loading and having a constant c(v). The theory covers the full history of loading namely that of ramp-loading followed by post-ramp-loading. However to determine the coefficient of consolidation during a constant rate of strain test only the ramp-loading portion of the theory is required. The tests in this study revealed that an increase in the displacement rate produces a more rapid rise in the back-calculated value of the consolidation coefficient.