Abstract
Based on a study of remolded young clay, this paper shows that the time effects observed at constant strain rate shearing, stress relaxation and creep processes in triaxial tests and the secondary compression for the consolidation process are commonly simulated by the time dependency of dilatancy. The fundamental aspect of the proposed procedure is to solve the following two state equations as a simultaneous equation, without using the plastic flow rule. One is an equation for specifying a volumetric strain due to consolidation and dilatancy. The other is the energy equation used in the original Cam Clay model, which gives a plastic shear strain corresponding to a plastic volumetric strain. The proposed procedure duplicates fairly well the time effects in undrained triaxial test. For the process of consolidation, the equation for specifying a volumetric strain and a constraint for restricting lateral deformation are solved as a simultaneous equation, because the energy equation may not hold for this process. The procedure provides a settlement curve which is consistent with the curve observed in a standard oedometer test for the normally consolidated region, and clarifies the following properties. 1) The secondary compression in remolded young clay is represented by the delayed occurrence of dilatancy. 2) In the standard oedometer test, the secondary compression takes place repeatedly at each step of loading, due to the mean effective stress which initially exists within the test specimen. 3) The secondary compression coefficient tends to decrease with increasing loading pressure, because the magnitude of dilatancy expected may decrease with the progress of step loading. 4) The secondary compression begins in the primary consolidation stage, depending on the value of the stress ratio. 5) The consolidation process value estimated by the procedure agrees well with the value monitored by triaxial equipment. (A)
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