Cyclic Undrained Triaxial Strength of Clay by a Round Robin Test

A round robin test to determine the cyclic undrained triaxial strength of a silty clay called Fujinomori clay was performed with the participation of 26 laboratories in Japan. One laboratory performed the cyclic simple shear test under constant volume and the data was used for the comparison with triaxial strength. The clay was distributed in the form of air-dried powder and preconsolidation was carried out from the slurry state in each laboratory under a prescribed specification. The clay specimens thus formed were subjected to cyclic undrained triaxial tests and the cyclic strengths thus obtained were compared. Static undrained triaxial tests were also performed at each laboratory. It was found that the scattering in the cyclic undrained strength data is quite small if the testing procedure and conditions are strictly specified. A very good agreement was obtained for the cyclic undrained strength data normalized by the corresponding static undrained strength. Lastly the cyclic undrained strength is compared with the data reported by other researchers.