Rock reinforcement design for unstable tunnels originally excavated in very poor rock mass

Malatya-Narli No: 7 railroad tunnel, situated at the central part of turkey, is a rail-road one that was initially excavated inside a valley of very poor quality rock mass. Due to the effect of the in-situ stress in the course of time, the deformations of the tunnel were exceeding the limit in which a huge collapse occurred and the tunnel was closed to the traffic.