Fractional order element model for one-dimensional compression of coral mud in the South China Sea

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