Deformation Characteristics of Clay under Traffic Load with Different Amplitudes and Frequencies

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.