A finite element method based on modified Alonso unsaturated soil constitutive model

Based on the revised ALONSO model, combined with the ABAQUS software platform, this paper compiled the USDFLD subroutine and obtained the stress-strain curve and the axial strain-volume deformation by simulating the triaxial shear test of the unsaturated soil to control the suction and confining pressure. The curve verifies the accuracy and reliability of the algorithm. The research results show that: (1) When the suction is the same, the higher the confining pressure is, the higher the yield point of the soil sample is. According to the comparison between experiment and simulation, the modified Alonso model can reflect the nonlinearity of the stress-strain relationship of the reshaped unsaturated soil sample and its plastic flow characteristics; (2) Compared with saturated soil, unsaturated soil has a higher yield point as a result of the suction. And the larger the suction is, the higher the yield point is, which proves that the model can simulate the influence of unsaturated soil liquid relative to the solid phase.