Cyclic softening of volcanic-ash cohesive soils

Key Points

• The aim is to evaluate the softening of saturated cohesive soils under cyclic loading conditions, especially during seismic events.
• Conducted static undrained shear tests with repeated undrained triaxial tests on volcanic ash soils.
• Proposed a new assessment formula incorporating cyclic amplitude strain as a damage parameter.
• Compared the effectiveness of the proposed method with traditional excess pore water pressure ratio.
• Cyclic loading leads to significant softening of plastic saturated fine soils.
• Cyclic amplitude strain is a more effective damage parameter than excess pore water pressure for assessing softening.