Dynamic Deformation Behavior and Cyclic Degradation of Ultrasoft Soil under Cyclic Loading

The dynamic deformation behavior of ultrasoft soil foundations is one of the major concerns in the field of geotechnical engineering. In this study, a series of cyclic triaxial tests with different vibration frequencies, f, and cyclic stress ratios, CSRs, has been conducted to investigate the dynamic deformation and cyclic degradation of ultrasoft soil from Binhai, China. The results reveal that the vibration frequencies have a substantial influence on the dynamic deformation of the ultrasoft soil. The inflection frequency is 3Hz. The value of the strain at failure of ultrasoft soil is between 0.99 and 1.6%, lower than that of general soft soils. The effect of f on the degradation index, , of ultrasoft soil is different from that of general clay soils. In addition, CSRs have a significant influence on the axial strain development mode. Compared with general soft soil, the effect of CSRs on the degradation index of ultrasoft soil is discussed. (C) 2016 American Society of Civil Engineers.