Deformation of over consolidated soft clay considering initial shear stress and frequency

The dynamic strain of saturated soft clay in Hangzhou under cyclic loading is researched by GDS cyclic triaxial system. The effect of cyclic stress ratio, initial shear stress, frequency and over consolidated ratio on dynamic strain is analyzed. It is observed that the dynamic strain increases with the increase of cyclic stress ratio. There is critical cyclic stress ratio of soft clay under cyclic loading. The value of critical cyclic stress ratio can also be obtained by dynamic strain and cyclic number of cycles curves. At the beginning of cyclic loading, the strain rate is bigger and then it decreases with the time. With the increase of cyclic stress ratio, the strain rate increases. The frequency influences the relationship between strain and cyclic number significantly and the dynamic strain decreases with the increase of frequency. However, the effect of frequency on dynamic strain and time and strain rate and time curves is indistinct. With the increase of initial shear stress, both the dynamic strain and strain rate increases. With the increase of over consolidated ratio, both the dynamic strain and strain rate decreases. It shows linear relationship between strain rate and time at log-scale. Based on the test results, the empirical equation between strain rate and time, and accumulative plastic model of soft clay under cyclic loading by integration are obtained.