Stability analysis and optimum support design of tunnel No. 14 in Tarik-dare coal mine

Abstract

This paper presents stability analysis of tunnel No.14 of Tarik-dare coal mine of Iran. The results gathered from field investigations and the geomechanical properties of rocks, were determined in the laboratory indicate that the rock masses of this area are weak. So, the excavated tunnels in this area need to have suitable support. To arriving to this purpose, this tunnel was modeled with phase2 software. Before using phase2 software we must modify in situ rock properties of this area to rock mass properties. For this purpose, Hoek-Brown (2002) failure criterion was used. After modeling this tunnel in phase2 software the results achieved from this model show that; displacements of around the tunnel are high and safety factures are very low, so tunnel need to be support. Because of that, phase2 software cannot apply steel arches directly, so we need to calculate amounts of pressure that steel arches exert to walls and apply to software. For this purpose, we use Hoek (1999) equations, and then stability analysis shows that; steel arch No.27 with spacing of 1.1m is the optimum support system for this tunnel.