Implementation and Application of a New Elastoplastic Model Based on a Multiaxial Criterion to Assess the Stress State near Underground Openings

The inelastic MSDPu (for Mises-Schleicher and Drucker-Prager unified) criterion has been developed over the last decade, and has been applied to simple problems for a wide range of geomaterials. This paper presents the approach taken to introduce this multiaxial criterion into a commercially available finite difference code using an elastoplastic framework. The paper begins with a brief review of the MSDPu formulation. Then, the main components of the elastoplastic model and the implementation procedure are described. The ensuing model, called MSDPu-EP (for MSDPu elastoplasticity model), is then validated against some existing and recently developed analytical solutions for the stress state around a circular opening. The newly developed model is further applied to evaluate the stress state near underground openings, using the geometry of a tunnel and of vertical backfilled stopes. A brief discussion follows.