The GDS hollow cylinder apparatus is applied in this study to stress simulate traffic load with varied cyclic stress ratios (CSRs) and frequencies on the soft clay in Hexi area, Nanjing, hereby making analysis on dynamic characteristics of soil under traffic load. It is released that the changes of strain curve along with CSRs can be divided into three types of stable, critical, and destructive. Meanwhile, the development of generalized shear strain can be predicted by using the frequency reduction coefficient. Soil gradually reaches a quasi-secondary equilibrium state at a lower CSR(less than 0.23), and the excess pore water pressure tends to be stable. While soil cannot reach quasi-secondary equilibrium state due to structural changes at a higher CSR, the excess pore water pressure gradually rises. The change of the excess pore water pressure at different frequencies is combined by the degree of plastic volume strain development and the cumulative number of plastic volume strain per unit time. The relationship between the secant elastic(shear) modulus E_d(G_d) and the cyclic normal(shear) strain amplitude ε_m(γ_m) can be expressed by the Hardin-Drnevich model, which shows that there is a negative linear correlation between the slope of 1/E_d~ε_m or 1/G_d~γ_m and CSR. Additionally, the frequencies have little effect on the secant modulus of the soil. By calculating the total equivalent damping ratio of the soil, it is found that the value of destruction of soil is about 0.018, which has little effect on frequencies. Meanwhile, the load frequencies have less influence on the total equivalent damping ratio compared with CSRs.

South China Sea coral mud is a calcareous ooze of marine rock and soil formed by the accumulation of bones and debris after the death of coral groups, which has special engineering properties. It is significant to investigate its time dependent long-term nonlinear deformation under load for the construction and long-term stability analysis of dredger fill islands and reefs. Three groups of one-dimensional consolidation compression tests of coral mud with different loading and unloading schemes were carried out, and the influence of stress history on its long-term deformation properties was explored by changing the loading time and loading-unloading loops. According to the three-stage law of coral mud’s instantaneous deformation, delayed attenuation deformation and delayed stable deformation under loading and unloading test conditions, the improved Burgers model was used to fit ε-t curves under different vertical stresses, which has high fitting accuracy. Meanwhile, after analyzing the model parameters, it was found that the instantaneous strain increment and its growth rate decrease with the increase of graded loading time, the duration of delayed attenuation under the final load decreases, and the delayed stable strain rate and the total strain increment under the final load decrease. In the same loading-unloading loops, the instantaneous strain increment in the unloading stage is smaller than that in the loading stage under the same vertical stresses. With the increase of loading-unloading loops, the instantaneous strain increment in each stage of loading and unloading decreases and is close to each other, the duration of delayed attenuation deformation, the delayed stable strain rate and total strain increment under the final load decrease. The effects of graded loading time and loading and unloading cycles on the long-term deformation properties of coral mud were studied to provide theoretical basis for surcharge preloading scheme in island reef construction.