Study on fractional-order elastic-plastic constitutive model of river silt based on critical state theory

The conventional constitutive models for mairne silts are usually built on different loading surfaces and plastic potential surfaces. In this paper, based on the concept of critical state, combined with the modified Cam-clay model and fractional-order calculus algorithm, the fractional-order elastic-plasticity constitutive model of the marine silt is studied and proposed. The basic characteristics of the model, such as the shear shrinkage, friction and stress history dependence of the marine silt, are comprehensively considered, and the parameters are easy to obtain. The experimental results and predicted results of different initial void ratios under undrained conditions are compared. The results show that the constitutive model can well simulate the strain hardening of the marine silt with different initial void ratios under undrained conditions. The predicted results of the model under different initial confining pressures are not consistent with the experimental results under fixed lambda value. By changing lambda, the stress-strain relationship of the marine silt can be effectively simulated. At the same time, the maximum deviator stress increases with the increase of the initial confining pressure, and the phenomenon that increases with the decrease of the initial void ratio can be predicted by this model.