Research on the Static Constitutive Model of Yellow River Silt Based on Fractional Order Non-Associated Plastic Flow

To accurately describe the mechanical behavior of Yellow River silt in practical engineering,this study established a static constitutive model based on fractional-order non-associated plastic flow theory.The non-associated plastic flow direction in p-q space was derived by applying the fractional derivative to the Modified Cam-Clay (MCC) yield surface.Within the framework of critical state theory,a state-dependent hardening modulus Π was formulated.Combined with Hooke’s law,an explicit expression of the incremental elasto-plastic flexibility matrix was obtained.The model parameters were calibrated using triaxial test results under drained conditions,and the model was validated under varying initial confining pressures (p₀) and void ratios (e₀).The results show that the model accurately captures the strain-hardening and dilatancy characteristics of Yellow River silt,with the average deviation between simulation and experimental data being less than 5%.This work presents a novel approach for static constitutive modeling of Yellow River silt and provides theoretical support for its application in foundation engineering within the Yellow River floodplain.