Effect of frequency and amplitude on dynamic behaviour, stiffness degradation and energy dissipation of saturated cohesive soil

Cohesive soil undergoes cyclic softening when experiences the dynamic loading conditions. Evaluation of strength loss under such loading conditions is essential for soil stability analysis. The present study investigates the cyclic response, stiffness degradation behaviour with number of loading cycles and cumulative energy dissipation characteristics within the soil mass of cohesive geomaterial. Slurry consolidated specimens of saturated cohesive soil were prepared to perform several series of strain controlled cyclic triaxial tests at varying loading frequency and axial strain amplitude under consolidated and unconsolidated testing conditions. A great influence of loading amplitude and frequency was observed on the hysteresis response and dynamic properties of cohesive soil under consolidated and unconsolidated testing conditions. Amount and rate of cyclic stiffness degradation in addition to cumulative dissipated energy were also evaluated at different dynamic loading (amplitude and frequency) and testing conditions (consolidated and unconsolidated). Cyclic strength and stiffness of saturated cohesive soil were obtained to be higher under consolidated testing conditions as compared to unconsolidated. A large decay in cumulative dissipated energy was observed with the increment in loading cycles.