ABSTRACT
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.
Notations
G | = | = Shear modulus |
D | = | = Damping ratio |
ru | = | = Pore pressure ratio |
ρbi | = | = Initial bulk density |
ρdi | = | = Initial dry density |
εa | = | = Axial strain |
f | = | = Loading frequency |
σd | = | = Deviatoric stress |
N | = | = Number of loading cycles |
υ | = | = Poisson’s ratio |
e | = | = Void ratio |
Sr | = | = Degree of saturation |
wi | = | = Initial water content |
δ | = | = Cyclic degradation index |
t | = | = Cyclic degradation parameter |
ΔW | = | = Cumulative energy dissipation |
ΔWT | = | = Cumulative energy dissipation for entire cyclic triaxial test |
Acknowledgments
Financial Support from IIT Gandhinagar is gratefully acknowledged. Any opinions, findings, and conclusions or recommendations expressed in this material are those of authors and do not necessarily reflect the views of IIT Gandhinagar.
Disclosure statement
No potential conflict of interest was reported by the authors.