CHARACTERIZATION AND MODELLING OF COUPLED CONSOLIDATION-CREEP BEHAVIOR OF RED CLAY

The long-term stability of slope in red clay region directly depends on the creep behavior of red clay. A specially designed tri-axial creep testing setup based on leverage loading method is adopted to investigate the creep behavior for red clay. Time history of axial displacement of specimen under drained condition is monitored subjected to stepwise axial load and constant confining stress. The Chen's method is used to transform the axial displacement time history equivalently into a cluster of creep curves for different loaded axial stresses. Furthermore, a threshold value of axial stress corresponding to the creep failure of red clay specimen is determined by using isochronal curve method. A novel element creep model incorporating soil consolidation theory and Kelvin rheological model is established to characterize the coupled consolidation-creep behavior of red clay. The model parameters of this element creep model are correlated reasonably with loaded axial stress by fitting on tested creep curves under part of adopted axial loads. The above correlations are furtherly incorporated into the creep model to predict the creep response of axial displacement of specimens under remaining axial stresses. The predicted axial displacement creep curves are compared with the measured data in tests. The good agreement found in comparison validates the effectiveness and accuracy of the presented element creep model.