2D and 3D finite element analysis of underground openings in an inhomogeneous rock mass

Abstract The finite element analysis of the underground openings excavated for Koyna hydroelectric project, Maharashtra, India, has been conducted. 2D and 3D models have been developed assuming that the rock mass obeys Drucker–Prager failure criterion. The computed deformations and the stress distribution, around these openings, have been compared with the in situ measurements. The study reveals that the 2D elasto-plastic analysis underestimates the deformations. On the other hand, the 3D elasto-plastic analysis yields results, which compare reasonably well with the in situ measurements. The effect of weak zones in the rock mass and creation of multiple cavities in the nonhomogeneous rock mass has also been considered in the analyses. Such a study is found to be very helpful for evaluating the stability of underground openings when extensive realistic input data is available for nonhomogeneous rock mass.