Abstract

The natural and induced stresses near openings in rock media usually have different magnitudes along different directions. These have to be taken into account for stability analysis. A general multiaxial criterion was developed to assess the strength of rocks and rock masses. The MSDP_u criterion was formulated in a modular manner, so it can be adapted to a variety of rock characteristics and structural calculations. The main equations are presented in this chapter. Specific conditions are described, including short term failure, initiation of damage, time effect, and the influence of scale and defects. In the case of rock mass, the criterion includes a continuity parameter that can be linked to the RMR geomechanical classification. The MSDP_u criterion is compared with other formulations to highlight some of the similarities and differences. Validation and application of the criterion are illustrated using laboratory tests results; additional studies also present the analysis of borehole stability and failure around large scale excavations.