UMAT redevelopment of elastoplastic damage constitutive model based on Mogi–Coulomb strength criterion

Deep rock mass is in a 3-dimensional high stress state before excavation and shows obvious nonlinear characteristics such as strain softening and elastic–plastic coupling after peak. As a result, the calculation results obtained by using existing constitutive models in numerical analysis of deep rock mass development engineering are often quite different from the facts. In view of this, based on the Mogi–Coulomb criterion, an elastoplastic damage constitutive model considering intermediate principal stress is established. By using the user-defined material UMAT subroutine interface provided by the large finite element software ABAQUS, the corresponding constitutive model was written in the Fortran language, and the damage correction calculation step was introduced to simulate the post-peak strain softening characteristics. The UMAT subroutine was used for triaxial compression numerical simulation tests. The experimental results show that the developed UMAT subroutine can effectively characterize the post-peak strain softening stage of marble with a high degree of fit with the actual experimental results. The research results can be further used for ABAQUS simulation and marble-related deep engineering.