Dynamic Properties of Soils—A Stress Path Approach

Abstract

The present study focuses on variation of dynamic properties of soils with change in stress path. Cyclic triaxial test, which is the most common laboratory test used to evaluate the dynamic properties of soils, suffers several limitations. Two major limitations are its inability to introduce continuous rotation of principal stress axes and the difference in simulated stress path when compared to vertically propagating shear waves. Present study focuses on quantifying one of these limitations, effect of change in stress path on the dynamic properties of soils, including shear modulus and damping ratio. Also, cyclic triaxial tests are created and performed in a way to simulate more realistic stress paths through slow dynamic loading. To keep the stress path vertical, minor principal stress is decreased with the increase in major principal stress by reducing the confining pressure. These tests showed that hysteresis loops became considerably broader with the stress path getting vertical, shear modulus decreased by about 25–45% and damping ratio increased by about 40–70% compared to conventional cyclic triaxial test. These results proved that the shear modulus is overestimated, and damping ratio is underestimated in a conventional triaxial test with inclined stress path, which does not actually represent a field scenario. The new tests with vertical stress path provide more realistic estimates of dynamic soil properties.