Underground structures, such as tunnels and caverns are of paramount importance among the civil structures. Due to the complexity of these structures and lack of advanced and accurate models in rock mechanics field, underground structures are designed approximately and with a high safety factors. Therefore, such projects become more expensive and less economics. Applying fracture mechanics models in this respect may be resulted in more benefits. In this paper, smeared crack model has been applied to predict rock failure. In order to illustrate the performance and integrity of the model three-point flexural tests were carried out on cylindrical rock specimens. OOFEM computer program with the ability of analyzing fracture mechanics models was used for test results analysis. The results show a very good agreement between the test results. and the numerical analysis. To obtain the model parameters corresponding to the rock specimens tested, sensitivity analysis were performed on the each of the model parameters and a series of Brazilian tests were also carried out in this respect.