Cyclic Triaxial Tests on Remoulded Clays

Abstract

Data are presented from cyclic triaxial tests on remoulded clays with load or displacement control. The ability of simple load control tests to predict strains developed in complex (storm profile) tests is found inadequate. It is suggested that only the minimum cyclic stress ratio associated with the fully weakened state has any direct design relevance. The minimum cyclic stress ratio varies with frequency. If data from load controlled tests are re‐analyzed to account for rate effects on shear strength then a constant value independent of frequency is observed. However, measurement is approximate and requires several extended tests. It is found that the fully weakened state for the soil tested can be achieved in a single displacement controlled test provided that 10,000 cycles at a mean double amplitude strain of at least 5% are applied. Irrespective of data re‐analysis, the minimum cyclic stress ratio measured in a single displacement controlled test is constant for frequencies less than 1/5 Hz. Within this limit the values of this parameter obtained from the two test modes agree to within 10%.