Alireza Afradi - Ph.D. Student of Mining Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran
Siamak Rezazadeh - Assistant Professor and Head of the Department of Mining and Geology, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran

Geological structures, state of stress, state of groundwater, role of gravity and performance of the geodynamic processes can affect engineering structures or construction projects on their own. Therefore, it cannot be expected from suggested methods and solutions and their application to be identical or lead to an identical result, due to various geological and tectonic conditions in different areas. Hence, the stability analysis and designing methods for foreseeing the retaining and support system for tunnels are diverse and came from different points of view. Designing a tunnel requires knowledge about its geological and geotechnical conditions so that the stabilization becomes possible by Rock Mass Rating (RMR) geomechanical classification systems and methods, considering the observations and results of these assessments. Boring the tunnel is performed using Drill-and- Blast operation and it has two stages. First stage includes designing and operating the initial structure in the upper part with the height of 5.5m and a semi-circular cross section. The second stage includes drilling in the lower part with the height of 3m and the width of 7.34m and with a rectangle cross section

Stability analysis, Drilling, Blasting, Rock Mass Rating (RMR) geomechanical classification system