Consideration of the time-dependent deformation behavior of cohesive soils may be important in the designs and analyses of embankments, excavations, submarine slopes and building foundations. Most methods for analyzing the time-dependent behavior are limited to contain special problems such as one dimensional consolidation or undrained creep. The objective of this paper, therefore, is the development of a general constitutive model for use in the numerical analyses of time-dependent geotechnical problems.
A new time-dependent constitutive model for normally consolidated clay was proposed based on the Extended Cam-clay model. The constitutive equation requires seven material parameters for considering creep and stress relaxation and eight material parameters for considering strain rate effect which can be determined by two undrained conventional triaxial compression tests with different strain rates and usual consolidation test.
The undrained conventional triaxial compression test with different strain rates were performed on remolded Ildo clay. Comparing the theoretical results with the experimental results from triaxial tests of remolded Ildo clay and San-Francisco Bay Mud, it becomes evident that the derived constitutive equation can explain the behavior such time-dependent as creep, stress relaxation and strain rate effect.
