Creep characteristics and model parameters of Qianhai soft soil

In order to explore the creep characteristics of the soft soil layer in coastal areas and establish the corresponding creep model, a direct shear creep test is conducted on the silty clay at the Haishangtianyuan East Station of Shenzhen Metro Line 12. The results show that the creep characteristics of the soft soil samples are related to the stress state. Under the consolidation pressure of 400 kPa, when the shear stress of the samples is small, the creep characteristics are not significant. With the increase of shear stress, the creep characteristics gradually become more significant. Using the creep rate, the creep process of the soft soil is divided into two stages: deceleration and stability stages. With the increase of shear stress, the elapsed time for each creep stage grows, and the corresponding strain increment increases gradually. The modified Singh-Mitchell model is used to simulate the creep characteristics of the soft soil. This model is widely used because it has fewer parameters and its constitutive equation is simple. The model parameters are calibrated using the test data at different reference time. It is found that the error between the calculated results and the test data is the smallest when the reference time t₁=1 h, and the prediction accuracy is higher.