Study on the Fractional Order Element Model of One-dimensional Compression of Coral Mud in the South China Sea

Coral mud is widely distributed in the South China Sea. Studying the deformation law of coral mud is of great significance for the development of the South China Sea. The one-dimensional compression of coral mud in the South China Sea has the typical deformation characteristics of soft soil. At the same time, due to its special properties, its deformation speed is faster than that of common soft soil, which is suitable for the study of deformation model. The one-dimensional compression deformation of soft soil is often simulated by the element model. However, the element parameters reflecting long-term deformation in the element model are fixed, which cannot accurately reflect the delayed plastic deformation. The Abel dashpot applied fractional order theory can better reflect the delayed plastic deformation characteristics of soil than the Newton dashpot. Therefore, the Burgers model is introduced to correct the fractional order corrected Burgers model. In this paper, the one-dimensional consolidation compression test of coral mud under approximate natural conditions lasted for 8-14 days per stage was carried out. The first 11 hours of readings were used to self-fit the Merchant model, Burgers model and fractional order corrected Burgers model, respectively. The model parameters obtained by fitting were used to predict the deformation after 11 hours. The self-fitting accuracy of the three models within 11 hours and the prediction accuracy after 11 hours were compared, and the parameters of each model and the deformation of each part were analyzed. The study found that the self-fitting accuracy of the fractional order corrected Burgers model was 23-65 times that of the Merchant model, and 6-18 times that of the Burgers model. The prediction accuracy is 5-35 times of Merchant model and 262-6213 times of Burgers model.