Abstract
Four types of triaxial compression tests were conducted on fully saturated normally consolidated clays under undrained conditions, in order to serve data for constructing a more general constitutive equation of clay. From the experimental results, we confirm the validity of those empirical equations proposed by Yong and Japp for the behaviors under constant strain rate loading and by Murayama et al. for stress relaxation. Equivalency of those two is clarified and then the empirical equation for creep phenomenon by Singh and Mitchell is derived based on those two equations. This concludes the existence of a unique stress-strain-time relation of clay. Adachi and Okano's constitutive equation was derived by extending Roscoe's original energy theory to be able to explain the time dependent properties of clay based on Perzyna's elasto/viscoplastic continuum and the experimental evidences obtained in this study.
