Undrained Creep Behavior of Clayey Soils

摘要

Clayey soils were used to prepare specimens possessing controlled pore solutionchemistry. Specimens were consolidated and equilibrated at four different soil suction levels. Various specimens were subjected to creep/recovery tests under drained and undrained conditions in conventional triaxial cells. The results were used to make comparisons with the behaviors predicted by a nonlinear viscoelastic model, based on power law, previously recommended by the parent project. Specimens of identical characteristics were subjected to high strain rates using a dynamic triaxial test system. Each test consisted of a series of stress controlled pulses of 50 msec duration. The pulse involved a ramp-up to a peak deviatoric stress and a ramp-down to zero. The peak stress was increased for the successive pulses. The response of the specimen, and the strain time history, was recorded. With the power laws developed and fitted to the creep/recovery data, in conjunction with the modified superposition principle, the response of specimens during dynamic testing has been predicted. Closer predictions were obtained by using the model developed for undrained testing conditions.