EXPERIMENTAL STUDY OF THE COMBINED EFFECT OF CYCLIC STRESS LEVEL AND LOADING FREQUENCY ON THE PERFORMANCE OF SOFT CLAYS

Undrained cyclic triaxial tests were conducted on soft clay to investigate the combined effect of cyclic stress level and loading frequency on the generation of excess pore water pressures and axial strains with the number of loading cycles or time. The results indicate that for a given cyclic stress level, the soil properties under various loading frequencies are slightly different if an identical number of loading cycles is considered, whereas they do not deviate from each other if an identical time is considered. In addition, failure occurs when the cyclic stress level exceeds a critical value irrespective of the loading frequency. The combined effect of a cyclic stress level and a loading frequency was studied by analyzing the strain rate in this stress-controlled cyclic loading test. It is shown that for a given cyclic stress level, the strain rate at various loading frequencies are almost same, implying that the influence of a cyclic stress level on the soft clay behavior is stronger compared to a loading frequency.