As we know, rock-masses are the complex structures. Failure of the rock-mass occur by the development of the fractures or slip surfaces, when the stresses get increased from the strength of the rock mass.
The failure process in rock-mass is complex, and mathematically difficult to quantify. Four failure criteria are:
- Coulomb's Criteria
- Mohr's Criteria
- Hoek and Bray Criteria
- Griffith's Criteria.