关键词: 回弹模量, 有限元实现, 等效切线刚度矩阵, 一致切线刚度矩阵

Abstract: A new model of dynamic resilient modulus was proposed to evaluate the subgrade soil by NCHRP 1-37A project in USA in 2004. The model is widely applied in engineering analysis since it considers the influence of volume stress and deviatoric stress. In the finite element analysis, however, the model is usually implemented using the equivalent tangent stiffness matrix determined from an equivalent dynamic triaxial test through local iteration at material points. In order to eliminate the error caused by the simplified method under complex stress state，the accurate consistent tangent stiffness matrix of dynamic resilient modulus is derived based on the general Hooke law. The model is implemented into ABAQUS by compiling the user material subroutine (UMAT); the finite element simulation is carried out for the cases of axial pressure and confining pressure; the simulated results demonstrate that the new method has a higher precision and efficiency compared to the existing simplified method based on an equivalent triaxial test. Finally, an analysis of typical asphalt pavement structure shows that, in order to improve the accuracy of the response of subgrade under complex stress state，it is necessary to use the consistent tangent stiffness matrix instead of the equivalent stress tangent stiffness matrix in pavement structure analysis.

Key words: resilient modulus, finite element implementation, equivalent tangent stiffness matrix, consistent tangent stiffness matrix