Deformational properties of Tianjin soft clay under different cyclic loading modes

Abstract

Subgrade soils are subjected to coupled dynamic-static and changeable-frequency traffic loading. Considering different cyclic modes of single-frequency, coupled dynamic-static and intermittent combined-frequency loading, deformational characteristics of the Tianjin soft clay in each vibration period were analyzed by triaxial testing. Results show that the accumulative plastic strain and pore pressure have quite different development patterns under coupled dynamic-static and intermittent combined-frequency loading than single-frequency cyclic loading. The combined-frequency loading caused a considerable increase of pore pressure increment, but intermittency resulted in a decrease. During the loading of either coupled dynamic-static or intermittency, the static loading caused the soft clays to be more resistant to later undrained cyclic loading. The intermittency and combined-frequency loading have an integrated effect on the accumulative plastic strain development pattern and increment during each vibration period. The degradation index under the coupled dynamic-static loading decreased much less than that under single-frequency loading, especially with increasing cyclic stress ratio.